bmj open · date submitted by the author: 25-apr-2014 complete list of authors: miranda, rafael;...

For peer review only

Electromyographic activity of preterm children in kangaroo care: a cohort study

Journal: BMJ Open

Manuscript ID: bmjopen-2014-005560

Article Type: Research

Date Submitted by the Author: 25-Apr-2014

Complete List of Authors: Miranda, Rafael; Instituto de Medicina Integral Prof. Fernando Fiqueira, Pós-graduação Cabral Filho, José; Instituto de Medicina Integral Prof. Fernando Fiqueira, Pós-graduação Diniz, Kaísa; Instituto de Medicina Integral Prof. Fernando Fiqueira, Pós-graduação Lima, Geisy Maria; Instituto de Medicina Integral Prof. Fernando Fiqueira, Unidade Canguru Vasconcelos, Danilo; Instituto de Medicina Integral Prof. Fernando Fiqueira, Pós-graduação

<b>Primary Subject Heading</b>:

Paediatrics

Secondary Subject Heading: Public health

Keywords: PAEDIATRICS, Developmental neurology & neurodisability < PAEDIATRICS, Community child health < PAEDIATRICS

For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml

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Electromyographic activity of preterm children in kangaroo care: a cohort study

Rafael Moura Miranda1; José Eulálio Cabral Filho

2; Kaísa Trovão Diniz

3; Geisy Maria

Souza Lima4; Danilo de Almeida Vasconcelos

5.

Affiliations: 1,2,3,5

Post Graduate Program of Instituto de Medicina Integral Prof.

Fernando Figueira (IMIP) – Recife – Brasil. 4Instituto de Medicina Integral Prof.

Fernando Figueira (IMIP) – Recife – Brasil.

Address correspondence to: Rafael Moura Miranda. Rua: Paula Batista, 270, Edifício

Morada Paula Batista, apto 203. Recife-PE/ Brasil; CEP: 51030-080.

[email protected].

Key-words: Kangaroo-Mother Care Method, Muscle Tonus, Electromyography, Child

Development, Motor Activity.

Word count: 2214

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ABSTRACT

Aim: The aim of this study was to compare the electromyographic activity in preterm

newborns placed or not in kangaroo care.

Methods: A cohort study was carried out at the Instituto de Medicina Integral Prof.

Fernando Figueira (IMIP), Recife, Brazil. Children were included if they were preterm

(38 newborns) with a gestational age of 27 to 34 weeks, and a corrected age of 35 weeks

at the time of the first electromyographic examination and had not been previously in

kangaroo care or term newborns (26 newborns) with a gestational age of 38 to 41

weeks. Surface electromyography (EMGs) was used to investigate muscle activity in

the brachial biceps at rest. The mean values for the groups and intervals were analyzed

using analysis of variance for repeated measurements and multiple comparisons.

Results: The RMS values for all the evaluations showed significant differences (F(5,108)=

56.69; p<0.001). The multiple comparisons showed that, in the preterm group in

kangaroo care, the RMS was greater at 48h compared to 0h, but not in the group not in

kangaroo care. The RMS in the term equivalent aged group in kangaroo care was also

greater when compared to the term group.

Conclusions: The kangaroo position increases electromyographic activity in the

brachial biceps of preterm newborns and those who have reached an age equivalent to

term. One limitation of the present study is the absence of a group of preterm newborns

not in kangaroo care followed up to age equivalent to term.

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Strengths and limitations of this study

▪ The results of the study add new information about the effects of kangaroo care for the

preterm.

▪ The early initiation of the kangaroo position may, like other early intervention

programs, have a positive influence on the motors responses of the child, thereby

making it possible to influence the motor development of the preterm newborn.

It is important to point out the innovative nature of this study, since there is a lack of

studies specifically evaluating electromyographic activity in children in kangaroo care.

▪ The sample size lower than the estimate is a factor that may diminish the reliability of

our findings. However with a sample power of 90%, the large differences found

between the means and the statistically significant figures may support our inference.

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INTRODUCTION

The Kangaroo Method (KM) is an intervention that aims to improve the health

of preterm low-weight newborns.1 There is evidence that the method provides various

benefits. These include an increase in body temperature,2,3

stabilization of cardio-

respiratory frequency,3,4

improved oxygenation of the brain,5

improved behavior (crying

and sleep),6-8

a reduction in pain4,9,10

and greater adherence to and duration of

breastfeeding.11-13

The method is also associated with a reduction in morbidity and

mortality,14,15

infections14

and the duration of hospitalization.15

The main feature of the method is the kangaroo position, whereby the child

remains in a vertical position supported on its stomach with limbs flexed, dressed in

light clothes, maintaining skin-to-skin contact with the adult’s thorax1. This position

allows the child to receive sensory, vestibular and postural stimuli and its effect on

motor responses in the newborns has thus aroused some interest among investigators.16

Recently, some studies16,17

have shown an increase in electromyographic activity in

preterms after different periods of time in kangaroo care (up to 96h) and that this

increase persists until an age equivalent to term. These results were pioneering, although

no study has yet been conducted in which these responses are compared with those of

preterm newborns not in kangaroo care and those of term newborns. The aim of this

study was thus to compare electromyographic activity in preterm newborns in kangaroo

care and newborns not placed in this position.

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METHODS

Participants

A cohort study was carried out, between July 2012 and January 2013, at the

Instituto de Medicina Integral Prof. Fernando Figueira (IMIP), in Recife, Brazil, with 64

newborns, 38 preterm hospitalized in the Kangaroo Unit and 26 term in the IMIP

nursery.

The IMIP’s Kangaroo Unit covers a surface-area of 600 m2

and has a ward with

22 beds for clinically stable preterm newborns (with a respiratory frequency of between

30–60 inspirations per minute, a heart rate of between 120–160 beats per minute,

peripheric oxygen saturation of over 89%, absence of signs of respiratory distress,

absence of cyanosis or pallor and pain.) The newborns had to tolerate food, to breathe

without the use of an apparatus and to weigh more than 1,250 grams.

The Kangaroo Unit provides medical and nursing services and also speech

therapy and physiotherapy. In this unit, the newborns, when referred by the medical

services, are evaluated and undergo an early stimulation program.

Newborns were included in the preterm group if they had a gestational age of 27

to 34 weeks and a corrected age of 35 weeks at the time of the first electromyographic

examination, and had not previously been in kangaroo care. Children were included in

the group of term newborns if they had a gestational age of 38-41 weeks. The exclusion

factors for all the newborns were: Apgar lower than 7 after 5 minutes, a history of grade

III or IV intracranial hemorrhage (diagnosed by way of transfontanelar ultra-sound and

included in medical records), convulsions, congenital infections (cytomegalovirus,

rubella, toxoplasmosis, syphilis and vertically transmitted HIV), malformations of the

Central Nervous System (hydrocephaly and genetic syndromes), infections of the

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central nervous system (meningitis or encephalitis), congenital cardiopathy, traumas

during delivery (injuries to the brachial plexus, dislocation of the hip and pelvis

fractures) and gastro-esophageal reflux disorder.

All these inclusion and exclusion factors were evaluated using data collected

from the medical records of patients evaluated by neonatologists at the Neonatal

Intensive Care Unit, the Kangaroo Unit and the IMIP nursery.

A non-probabilistic convenient sample of newborns was selected, the size of the

sample being based on a previous study 17

that found variance of 2.6 in

electromyographic activity and estimated the minimum difference between means to be

2 µV. With an alpha error of 0.05 and power of 90%, 21 individuals were calculated for

each group.

The project for this study was submitted to the IMIP’s Ethics Committee for

Research involving Human Beings and was approved (Nº 1,902). The parents or

guardians who agreed to participate signed terms of free informed consent.

Collection procedure

The electromyographic signal was obtained using a Miotool 400 ®

electromyograph (Miotec Equipamentos Biomédicos – Brazil). A system of self-

adhering Ag/AgCl channels and electrodes (Meditrace 100®

) was used to connect the

equipment to the body of the child under examination. The electromyograph was

connected to a laptop with Myographic 2.0 software (Miotec Equipamentos Biomédicos

- Brazil) to process the myoelectrical records. The sampling frequency was 2000 Hz and

the electromyograms were amplified 2000 times.

The electromyographic signal was captured using two electrodes placed on the

central portion of the left brachial bíceps muscle, between the motor point and the

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myotendinous junction, parallel to the muscle fibers, as recommended by the SENIAM

(Surface Electromyography for the Non-Invasive Assessment of Muscles) project.18

The

electrodes were adjusted to ensure the distance between them did not exceed 20 mm and

the reference electrode was always placed on the lateral malleolus contralateral to the

muscle under evaluation.

When the measurements were made, the child was placed on a small wedge-

shaped cushion at angle of 30° relative to the horizontal plane. Electromyographic

activity was captured with the children in Brazelton state 4 or 5 (inactive alert or alert

with activity) respectively.19

Three groups were drawn up: 1) preterm newborns in kangaroo care (PT –

KAN); 2) preterm newborns not in kangaroo care (PT – NKAN); and 3) term newborns

(T). In the PT – KAN group, electromyographic activity was measured before being in

kangaroo care (0h). Immediately after taking the first reading, the children were placed

for the first time in the Kangaroo Position. The Kangaroo Position adopted was that

recommended by the Kangaroo Unit, in which the newborn is positioned against the

adult’s chest, face down, wrapped in a strip of flexible cloth. Subsequent readings were

taken after 48h of the Kangaroo Position and, finally, at term-equivalent age (40 ± 1

weeks). In the PT – NKAN group the measurements were made at 0h and 48h. In the T

group electromyographic activity was measured only once, at a chronological age of

24h. The newborns were kept in the kangaroo position for 8-12 hours per day, until the

evaluation after 48h.

During data collection, the researchers asked the Kangaroo Unit not to give the

newborns physiotherapy. The newborns did not, therefore, undergo any kind of early

motor stimulation during data collection, except for oral stimulation by speech

therapists, when necessary.

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Treatment of Data and Statistical analysis

For analysis of muscle activity the signal was transformed into the Root Mean

Square (RMS) and normalized.20,21

For normalization, 100% corresponding to the peak

electromyographic signal was taken as a reference. The signal was captured for 30s,

with a window of 10s before the next measurement.

Comparison of the means of the groups was carried out after establishing the

normality of the distribution (Kolmogorov-Smirnov Test) and the homogeneity of

variance (Levene Test), by analysis of variance for repeated measurements, followed by

multiple comparisons (Holm-Sidak’s post hoc test) to test for the differences between

the two groups. The alpha error for rejection of the null hypothesis was 0.05.

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RESULTS

The clinical and biological characteristics of the newborns in each group can be

seen in Table 1.

Table 1: Clinical and Biological Characteristics of Newborns.

PT-KAN

(n= 25)

PT-NKAN

(n=13)

T

(n=26)

Variables relating to newborn

Gestational age, weeks 31.06 (2.24) 31.21 (1.68) 39.27 (0.92)

Birthweight, grams 1314 (391.66) 1433.08 (349.72) 3191.36 (476.06)

Apgar score after 5’, Md (min-

max)

9 (7-10)

9 (7-9)

9 (8-10)

Corrected age on first

measurement (0h), weeks

34.86 (1.66)

33.93 (1.17)

39.84 (0.85)

For continuous variables the mean (SD) are given; for ordinal variables (Apgar) the median (min-max).

Comparison of the RMS between measurements (Table 2) shows them to be

different to a statistically significant extent: (F(5,108)= 56.69; p<0.001). The post hoc

multiple comparisons (Holm-Sidak Method) showed that in the PT-KAN the RMS was

greater at 48h (p=0.004) and at an age equivalent to term (p=0.004) compared with the

measurement at 0h, although there is no statistically significant difference between the

measurements at 48h and at age equivalent to term. In the PT-NKAN group no

significant difference was found between 0h and 48h.

The RMS in the PT-KAN group at age equivalent to term was greater than in T

(p=0.004).

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Table 2: Electromyographic activity (RMS normalized) of the left brachial biceps

muscle in preterm newborns in kangaroo care or not and in term newborns.

Intervals between

measurements

Groups

PT-KAN

(��± DP)

PT-NKAN

(��± DP)

T

(��± DP)

0h

31.85±6.93

37.59±4.42

-

48h

49.30±4.91

38.17±3.10

-

IET/IAT

48.03±5.56

-

27.12±5.70

RMS: Root Mean Square. PT-KAN: group of preterm newborns in kangaroo care. PT-NKAN: group of preterm

newborns not in kangaroo care. T: group of term newborns. IET: age equivalent to term (for PT-KAN group).

IAT: age on term (for T group). *Analysis of variance for repeated measurements: F(5,108)= 56.69; p<0.001.

Multiple comparisons (Holm-Sidak Test): in the PT-KAN group: 0h x 48h (p=0.004), 0h x IET (p=0.004).

Between PT-KAM and T groups: IET x IAT (p=0.004).

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DISCUSSION

The results of this study showed an increase in electromyographic activity of the

brachial biceps muscle in preterm newborns placed for 48h in kangaroo care, which did

not occur in the control group. These data suggest that the kangaroo position changes

myoelectrical activity in these children, at least in the case of the flexor muscle

evaluated here.

A similar result was observed in a previous study.17

Preterm newborns placed for

24h in kangaroo care saw an increase in the myoelectrical activity of flexor muscles and

this increase persisted even after 24h out of this position.

Later, Diniz et al16

observed a growing increase in electromyographic activity in

the brachial biceps muscle during 96h in kangaroo care. As in our study, these authors

observed this effect 48h after being placed in kangaroo care. However, it is important to

note the presence of a control group in our study which gives added weight to our

results. Also in accordance with the findings of Diniz et al16

, the effect on

electromyographic activity remained constant until an age equivalent to term.

It is worth noting that the electromyographic activity in the PT-KAM group, at an

age equivalent to term, was significantly greater than that in term children. This finding

may be associated with the fact that preterm children received extra-uterine stimuli up

to age equivalent to term, especially those provided by the kangaroo position. However,

the term children to not have the opportunity to receive such stimuli.

The effect of the kangaroo position on inducing a more flexed posture in preterm

neonates is already known,22,23

and this also suggest a specific effect of the kangaroo

position on flexor muscles.

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Recently Schneider et al24

using Transcranial Magnetic Stimulation, showed that

preterm newborns undergoing the kangaroo method had better connectivity and

synaptic efficacy of the motor routes in the brain in adolescence. Another study25

provides electroencephalic evidence to the effect that the kangaroo interventions makes

the brain mature faster in health preterm children. These findings are relevant, since

changes in the myoelectrical parameter in response to the kangaroo position found in

our study may be associated with faster maturation of the brain and better performance

of cerebral motor activity. The mechanism behind this central motor activation on the

peripheral myoelectrical response is still a matter of debate, but it corroborates the

conclusion that the kangaroo position has an effect on muscle response.

Delays in neuropsychomotor development are frequent in preterm newborns

owing to insufficient organization of their nervous systems.8,24

However, a recent meta-

analysis26

concluded that early intervention programs for premature babies have a

positive influence on motor development and there is evidence that tactile, synesthesic

and vestibular stimuli may influence the motor abilities of newborns.27,28

We suggest, then, that early initiation of the kangaroo position may, like other

early intervention programs, have a positive influence on the motor development of the

child. This hypothesis may be sustained by the characteristics of the kangaroo position,

which provide different stimuli for the newborn. However, given that, in the kangaroo

position, the preterm newborn remains in skin-to-skin contact with the adult chest, with

its limbs flexed, in a vertical position1 receiving various environmental inputs, the

sensory, postural and vestibular stimuli furnished when in this position16

may cause a

considerable increase in motor activity.

This evidence suggests that the kangaroo position has a positive influence on

motor activity in newborns that is physiologically represented by an alteration in

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myoelectrical parameters as observed here. Moreover, myoelectrical alterations in a

flexor muscle is a relevant physiological response, since the kangaroo position involves

maintaining a flexed posture.

One limitation of the present study is the absence of a group of preterm newborns

not in kangaroo care followed up to age equivalent to term, as this would shed light on

whether the increase in electromyographic activity in the preterm children at age

equivalent to term is only related to the growth and development of the child and not the

influence of the kangaroo position. However, the reduced myoelectrical response in

group T suggests that it is the kangaroo position and not the growth of the child per se

that is responsible for the changes in electromyographic activity observed here. Apart

from the this limitation, the sample size lower than the estimate is a factor that may

diminish the reliability of our findings. However with a sample power of 90%, the large

differences found between the means and the statistically significant figures may

support our inference.

In conclusion, the results of this study provide evidence that the kangaroo

position in the short term causes an increase in myoelectrical activity in preterm

newborns that persists until an age equivalent to term. In addition, it may be that the fact

that electromyographic activity in premature children at age equivalent to term is greater

than that of term newborns is related to the different stimuli (tactile, synesthetic and

vestibular) that they receive. It is thus suggested that this intervention induces changes

in the flexor function of the muscle (flexor tonus), thereby making it possible to

influence the motor development of the newborn. The age to which (in the long term)

these effects persist and whether they are positive effects need to be examined in further

studies.

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It is important to point out the innovative nature of this study, since there is a

lack of studies specifically evaluating electromyographic activity in children in

kangaroo care. It is suggested that further research be carried out to investigate the

electromyographic effect of the kangaroo position on other muscles involved in the

postural system, in both term and preterm newborns.

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Acknowledgements: We wish to thank the babies, parents and, especially, thank the

nursing technicians of the Kangaroo Unit at the Instituto de Medicina Integral Prof.

Fernando Figueira (IMIP), Recife – Brazil.

Contributors: RMM – Preparation of the study project, data collection and supervision

thereof, statistical analysis, research articles in the database, preparation of the article;

and approved the final manuscript as submitted; JECF – Guidance for the preparation of

the study project, supervision of data collection, statistical analysis, research articles in

the database; guidance and preparation of the article; and approved the final manuscript

as submitted; KTD – Preparation of the study project, data collection and supervision

thereof, data processing, statistical analysis, research articles in the database,

preparation of the article; and approved the final manuscript as submitted; GMSL –

Preparation of the study project, data collection and supervision thereof; and approved

the final manuscript as submitted; DAV: Preparation of the study project, supervision of

data collection, data processing; and approved the final manuscript as submitted;

Funding Source: Fundação de Amparo à Ciência e Tecnologia do Estado de

Pernambuco – FACEPE (APQ – 0552–4.08/100).

Financial Disclosure: Miranda RM was supported by post graduate scholarship from

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Diniz KT

was supported by post graduate scholarship from Fundação de Amparo à Ciência e

Tecnologia do Estado de Pernambuco (FACEPE).

Conflict of Interest: the authors declare that they have no competing interests.

Ethics approval: IMIP’s Ethics Committee for Research involving Human Beings (Nº

1,902)

Data sharing statement: no additional data available.

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the electromyographic activity of preterm children: a follow-up study. BMC Pediatr

2013; 13:79.

17. Barradas J: Kangaroo position effect on the flexor muscle tone of newborn preterm.

Fernando Figueira: Dissertation. Post Graduate Department the Institute of Integrated

Medicine Prof; 2010.

18. Hermens HJ, Freriks B, Disselhorst-Klug C, et al. Development of

recommendations for SEMG sensors and sensor placement procedures. J Electromyogr

Kinesiol 2000;10:361-74.

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19. Als H, Tronick E, Lester BM, et al. The Braselton neonatal behavioral assessment

scale (BNBAS). J Abnorm Child Psychol 1977;5:215-29.

20. Bolgla LA, Uhl TL. Reliability of electromyographic normalization methods for

evaluating the hip musculature. J Electromyogr Kinesiol 2007;17:102–111.

21. Lehman GJ, McGill SM. The importance of normalization in the interpretation of

surface electromyography: a proof of principle. J Manipulative Physiol Ther 1999;

22:444–46.

22. Barradas J, Fosceca A, Guimarães CLN, et al. Relationship between positioningof

premature infants in kangaroo mother care and early neuromotor development. J Pediatr

(Rio J) 2006;82:475–80.

23. Ferber SG, Makhoul IR. The effect of skin-to-skin contact (kangaroo care) shortly

after birth on the neurobehavioral responses of the term newborn: a randomized.

Controlled Trial. Pediatrics 2004;113:858–65.

24. Schneider C, Charpak N, Ruiz-Peláez JG, et al. Cerebral motor function in very

premature-at-birth adolescents: a brain stimulation exploration of kangaroo mother care

effects. Acta Paediatr 2012;101:1045-53.

25. Kaffashi F, Scher MS, Ludington-Hoe SM, et al. An analysis of

the kangaroo care intervention using neonatal EEG complexity: a preliminary study.

Clin Neurophysiol 2013;124:238-46.

26. Spittle A, Orton J, Anderson P, et al. Early developmental intervention programmes

post-hospital discharge to prevent motor and cognitive impairments in preterm infants.

Cochrane Database Syst Rev 2013;(6):CD005495.

27. Field TM, Schanberg SM, Scafidi F, et al. Tactile/kinesthetic stimulation effects on

preterm neonates. Pediatrics 1986; 77:654–58.

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28. Symington AJ, Pinelli J. Developmental care for promoting development and

preventing morbidity in preterm infants. Cochrane Database Syst Rev 2013;(6):CD

001814.

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Electromyographic activity of preterm newborns in kangaroo position: a cohort study

Journal: BMJ Open

Manuscript ID: bmjopen-2014-005560.R1


Date Submitted by the Author: 14-Jul-2014



Paediatrics




BMJ Open on 13 F


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j.com/

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1

Electromyographic activity of preterm newborns in kangaroo position: a cohort

study



3; Geisy Maria


5.







[email protected].



Word count: 3628

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ABSTRACT

Aim: to compare the electromyographic activity of preterm newborns placed in

kangaroo position with the same activity of newborns not placed in this position.


Fernando Figueira (IMIP), Recife, Brazil. Surface electromyography (EMGs) was used

to investigate muscle activity in the brachial biceps at rest. Three groups were designed:

1) preterm newborns in kangaroo position (PT – KAN), its electromyographic activity

being recorded at 0h (immediately before starting this position), and then at 48h from

beginning the position (but newborns being kept in the kangaroo position for 8-12 hours

per day) and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not in

kangaroo position (PT – NKAN), the measurements being made at 0h and 48h; and 3)

term newborns (T), in which measurements were made at 24h of chronological age.

Statistical comparisons were made by analysis of variance for repeated measurements

followed by the multiple comparisons tests (Holm-Sidak’s).

Results: The RMS values showed significant differences among the groups (F(5,108)=

56.69; p<0.001). The multiple comparisons showed that, RMS was greater at 48h

compared to 0h in the preterm group in kangaroo position, but not in the group not

submitted to kangaroo position. The RMS in the term equivalent aged group in

kangaroo position was also greater when compared to the term group.


brachial biceps of preterm newborns and those who have reached the age equivalent to


not in kangaroo position followed up to age equivalent to term.

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▪ The results of the study add new information about the effects of Kangaroo-Mother

Care for the preterm.


programs, have a positive influence on the motor responses of the neonate, thereby



studies specifically evaluating electromyographic activity in newborn in kangaroo

position.

▪ The sample size lower than the estimate in one of the Groups (PT-NKAN) is a factor

that may diminish the reliability of our findings. However the sample power of 90%, the

large differences found between the means and the statistically significant figures may


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4

INTRODUCTION








and sleep),6-8



breastfeeding.11-13


mortality,14,15

infections14


The main feature of the method is the kangaroo position, whereby the newborn



allows the neonates to receive sensory, vestibular and postural stimuli and its effect on




preterm newborns after different periods of time in kangaroo position (up to 96h) and

that this increase persists until an age equivalent to term. These results were pioneering,

although no study has yet been conducted in which these responses are compared with

those of preterm newborns not in kangaroo position and those of term newborns. The

aim of this study was thus to compare electromyographic activity in preterm newborns

in kangaroo position and newborns not placed in this position.

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5

METHODS

Participants



hospitalized newborns, from which 38 preterm in the Kangaroo Unit sector and 26 term

in the Nursery sector of the IMIP hospital.


and has a ward with









Newborns were included in the preterm groups if they had a gestational age of

27 to 34 weeks and a corrected age until 35 weeks at the time of the first

electromyographic examination, and had not previously been in kangaroo position.

Neonates were included in the group of term if they had a gestational age of 38-41

weeks. Neonates were included only when their Brazelton state during

electromyographic recording was 4 or 5 (inactive alert or alert with activity).

The exclusion factors for all the newborns were: Apgar lower than 7 in the 5th

minute, a history of grade III or IV intracranial hemorrhage (diagnosed by way of

transfontanelar ultra-sound and included in medical records), convulsions, congenital

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infections (cytomegalovirus, rubella, toxoplasmosis, syphilis and vertically transmitted

HIV), malformations of the Central Nervous System (hydrocephaly and genetic

syndromes), infections of the central nervous system (meningitis or encephalitis),

congenital cardiopathy, traumas during delivery (injuries to the brachial plexus,

dislocation of the hip and pelvis fractures) and gastro-esophageal reflux disorder.



Intensive Care Unit, the Kangaroo Unit sector and the Nursery sector.






each group.


Research involving Human Beings and was approved (protocol no. 1902). The parents

or guardians who agreed to participate signed terms of free informed consent.



electromyograph (Miotec Equipamentos Biomédicos – Brazil). A system of channels

and self-adhesive 4.2 mm diameter Ag/AgCl electrodes (Meditrace 100®

) was used to

connect the equipment to the body of the newborn under examination. The

electromyograph was connected to a laptop with Myographic 2.0 software (Miotec

Equipamentos Biomédicos - Brazil) to process the myoelectrical records. The sampling

frequency was 2000 Hz and the electromyograms were amplified 2000 times.

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The electromyographic signal was captured using two surface electrodes placed

on the central portion of the left brachial bíceps muscle, between the motor point and

the myotendinous junction, parallel to the muscle fibers, as recommended by the

SENIAM (Surface Electromyography for the Non-Invasive Assessment of Muscles)

project.18

The electrodes were adjusted to ensure the distance between them did not

exceed 20 mm and the reference electrode was always placed on the lateral malleolus

contralateral to the muscle under evaluation.

When the measurements were made, the newborn was placed on a small wedge-


activity was captured with the newborn in Brazelton state 4 or 5 (inactive alert or alert


Three groups were designed: Group 1 (n=25): preterm newborns in kangaroo

position (PT – KAN); 2) Group 2 (n=13): preterm newborns not in kangaroo position

(PT – NKAN); and 3) Group 3 (n=16): term newborns (T).

In the PT – KAN group, electromyographic activity was first recorded before

neonate being in kangaroo position (0h). Immediately after taking this record, the

neonates were placed for the first time in the kangaroo position. The kangaroo position

adopted was that recommended by the Kangaroo Unit, in which the newborn is

positioned against the adult’s chest, face down, wrapped in a strip of flexible cloth.

Subsequent recordings were taken immediately after 48h of the kangaroo position and,

finally, at term-equivalent age (40 ± 1 weeks). The newborns were kept in the kangaroo

position for 8-12 hours per day, until the evaluation after 48h.

In the PT – NKAN group the measurements were made at 0h and 48h. In the T

group electromyographic activity was measured only once, at a chronological age until

24h.

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For normalization, 100% corresponding to the

maximum peak electromyographic signal was taken as a reference. A period of 10s of

the total electromyographic reading (30s) was used.

Comparison of the means of the groups was carried out after verifying the




each two groups. The alpha error for rejection of the null hypothesis was 0.05.

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9

RESULTS


seen in Table 1.


PT-KAN

(n= 25)

PT-NKAN

(n=13)

T

(n=26)





max)

9 (7-10)

9 (7-9)

9 (8-10)



34.86 (1.66)

33.93 (1.17)

39.84 (0.85)


Variances analyses comparison of the RMS among measurements (Table 2)

demonstrated a significant difference (F(5,108)= 56.69; p<0.001). The post hoc multiple

comparisons (Holm-Sidak Method) showed that in the PT-KAN Group the RMS was

greater at 48h (p=0.004) and at age equivalent to term (p=0.004) compared with the

measurement at 0h, but there is no statistically significant difference between the



The RMS in the PT-KAN group at age equivalent to term was greater than in the

T Group (p=0.004).

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muscle in preterm newborns in kangaroo position or not and in term newborns.

Intervals between

measurements

Groups

PT-KAN

(��± DP)

PT-NKAN

(��± DP)

T

(��± DP)

0h

31.85±6.93

37.59±4.42

-

48h

49.30±4.91

38.17±3.10

-

TEA and TA

48.03±5.56

-

27.12±5.70


newborns not in kangaroo position. T: group of term newborns. TEA: term equivalent age (for PT-KAN group).

TA: term age (for T group). *Analysis of variance for repeated measurements: F(5,108)= 56.69; p<0.001. Multiple

comparisons (Holm-Sidak Test): in the PT-KAN group: 0h x 48h (p=0.004), 0h x TEA (p=0.004). Between PT-

KAN and T groups: TEA x TA (p=0.004).

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DISCUSSION


brachial biceps muscle in preterm newborns maintained in a kangaroo care environment

for 48h even when placed on kangaroo position during only to 8 – 12h by day, which

did not occur in the control group. These data suggest that the kangaroo position

changes myoelectrical activity in these newborn, at least in the case of the flexor muscle

evaluated here.



24h in kangaroo position saw an increase in the myoelectrical activity of flexor muscles

and this increase persisted even after 24h out of this position.



the brachial biceps muscle during 96h in kangaroo position. As in our study, these

authors observed this effect 48h after being placed in kangaroo position. However, it is

important to note the presence of a control group in our study which gives added weight

to our results. Also in accordance with the findings of Diniz et al16

, the effect on


It is worth noting that the electromyographic activity in the PT-KAN group, at an

age equivalent to term, was significantly greater than that in term newborns, although a

similarity between them was expected. This increased electromyographic activity might

be associated with the fact that preterm newborns received extra-uterine stimuli up to

age equivalent to term, especially those provided by the kangaroo position. However,

the term newborns to not have the opportunity to receive such stimuli.

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using transcranial magnetic stimulation, showed that




the brain mature faster in health preterm newborns. These findings are relevant, since

changes in the myoelectrical parameter in response to kangaroo position found in our

study may be associated with faster maturation of the brain and better performance of

the cerebral structures controlling motor activity. The mechanism behind this central

motor activation on the peripheral myoelectrical response is still a matter of debate, but

it corroborates the conclusion that the kangaroo position has an effect on muscle

response.




analysis26






preterm newborns. This hypothesis may be sustained by the characteristics of the

kangaroo position, which provide different stimuli for the newborn. However, given

that, in the kangaroo position, the preterm newborn remains in skin-to-skin contact with

the adult chest, with its limbs flexed, in a vertical position1 receiving various

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13

environmental inputs, the sensory, postural and vestibular stimuli furnished when in this

position16

may cause a considerable increase in motor activity. This evidence suggests

that the kangaroo position has a positive influence on motor activity in newborns that is

physiologically represented by an alteration in myoelectrical parameters as observed

here. Moreover, myoelectrical alterations in a flexor muscle are a relevant physiological

response, since the kangaroo position involves maintaining a flexed posture.



whether the increase in electromyographic activity in the preterm newborns at age

equivalent to term is only related to the growth and development of the neonates and not

the influence of the kangaroo position. However, the reduced myoelectrical response in

group T suggests that it is the kangaroo position and not the growth of the newborns per

se that is responsible for the changes in electromyographic activity observed here. Apart

from this limitation, the sample size was lower than the estimate so it is a factor that

may diminish the reliability of our findings. However with a sample power of 90%, the


support our inferences.

In conclusion, although this is a preliminary study their results provide evidence

that the kangaroo position in the short term induces an increase in myoelectrical activity

in preterm newborns which persists until the age equivalent to term. In addition, it may

be that the fact that electromyographic activity in premature newborn at age equivalent

to term is greater than that of term newborns is related to the different stimuli (tactile,

synesthetic and vestibular) that they receive. It is thus suggested that this intervention

induces changes in the flexor function of the muscle (flexor tonus), thereby making it

possible to influence the motor development of the newborn. The age to which (in the

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long term) these effects persist and whether they are positive effects need to be

examined in further studies.

It is important to point out the innovative nature of this study, although

preliminary, since there is a lack of studies specifically evaluating electromyographic

activity in newborn in kangaroo position. It is suggested that further research be carried

out to investigate the electromyographic effect of the kangaroo position on other

muscles involved in the postural system, in both term and preterm newborns.

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Ethics approval: IMIP’s Ethics Committee for Research involving Human Beings

(protocol no.1902)


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16

REFERENCES








4. Johnston C, Campbell-Yeo M, Fernandes A, et al. Skin-to-skin care for procedural

pain in neonates. Cochrane Database Syst Rev. 2014 (4):CD008435.















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21:601-5.






Rev 2013;(6):CD002771.





2013; 13:79.






Kinesiol 2000;10:361-74.



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22:444–46.



(Rio J) 2006;82:475–80.

















001814.

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1


study



3; Geisy Maria


5.







[email protected].



Word count: 3628

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2

ABSTRACT

Aim: to compare the electromyographic activity of preterm newborns placed in

kangaroo position with the same activity of newborns not placed in this position.


Fernando Figueira (IMIP), Recife, Brazil. Surface electromyography (EMGs) was used

to investigate muscle activity in the brachial biceps at rest. Three groups were designed:

1) preterm newborns in kangaroo position (PT – KAN), its electromyographic activity

being recorded at 0h (immediately before starting this position), and then at 48h from

beginning the position (but newborns being kept in the kangaroo position for 8-12 hours

per day) and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not in

kangaroo position (PT – NKAN), the measurements being made at 0h and 48h; and 3)


Statistical comparisons were made by analysis of variance for repeated measurements

followed by the multiple comparisons tests (Holm-Sidak’s).

Results: The RMS values showed significant differences among the groups (F(5,108)=

56.69; p<0.001). The multiple comparisons showed that, RMS was greater at 48h

compared to 0h in the preterm group in kangaroo position, but not in the group not

submitted to kangaroo position. The RMS in the term equivalent aged group in

kangaroo position was also greater when compared to the term group.




not in kangaroo position followed up to age equivalent to term.

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position.


that may diminish the reliability of our findings. However the sample power of 90%, the



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4

INTRODUCTION








and sleep),6-8



breastfeeding.11-13


mortality,14,15

infections14





allows the neonates to receive sensory, vestibular and postural stimuli and its effect on




preterm newborns after different periods of time in kangaroo position (up to 96h) and

that this increase persists until an age equivalent to term. These results were pioneering,

although no study has yet been conducted in which these responses are compared with

those of preterm newborns not in kangaroo position and those of term newborns. The

aim of this study was thus to compare electromyographic activity in preterm newborns

in kangaroo position and newborns not placed in this position.

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5

METHODS

Participants



hospitalized newborns, from which 38 preterm in the Kangaroo Unit sector and 26 term

in the Nursery sector of the IMIP hospital.


and has a ward with










27 to 34 weeks and a corrected age until 35 weeks at the time of the first

electromyographic examination, and had not previously been in kangaroo position.


weeks. Neonates were included only when their Brazelton state during




transfontanelar ultra-sound and included in medical records), convulsions, congenital

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6








Intensive Care Unit, the Kangaroo Unit sector and the Nursery sector.






each group.


Research involving Human Beings and was approved (protocol no. 1902). The parents

or guardians who agreed to participate signed terms of free informed consent.




and self-adhesive 4.2 mm diameter Ag/AgCl electrodes (Meditrace 100®

) was used to

connect the equipment to the body of the newborn under examination. The

electromyograph was connected to a laptop with Myographic 2.0 software (Miotec

Equipamentos Biomédicos - Brazil) to process the myoelectrical records. The sampling

frequency was 2000 Hz and the electromyograms were amplified 2000 times.

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project.18

The electrodes were adjusted to ensure the distance between them did not

exceed 20 mm and the reference electrode was always placed on the lateral malleolus

contralateral to the muscle under evaluation.

When the measurements were made, the newborn was placed on a small wedge-


activity was captured with the newborn in Brazelton state 4 or 5 (inactive alert or alert


Three groups were designed: Group 1 (n=25): preterm newborns in kangaroo

position (PT – KAN); 2) Group 2 (n=13): preterm newborns not in kangaroo position

(PT – NKAN); and 3) Group 3 (n=16): term newborns (T).

In the PT – KAN group, electromyographic activity was first recorded before

neonate being in kangaroo position (0h). Immediately after taking this record, the


adopted was that recommended by the Kangaroo Unit, in which the newborn is

positioned against the adult’s chest, face down, wrapped in a strip of flexible cloth.

Subsequent recordings were taken immediately after 48h of the kangaroo position and,

finally, at term-equivalent age (40 ± 1 weeks). The newborns were kept in the kangaroo

position for 8-12 hours per day, until the evaluation after 48h.

In the PT – NKAN group the measurements were made at 0h and 48h. In the T

group electromyographic activity was measured only once, at a chronological age until

24h.

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For normalization, 100% corresponding to the

maximum peak electromyographic signal was taken as a reference. A period of 10s of

the total electromyographic reading (30s) was used.

Comparison of the means of the groups was carried out after verifying the





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RESULTS


seen in Table 1.


PT-KAN

(n= 25)

PT-NKAN

(n=13)

T

(n=26)





max)

9 (7-10)

9 (7-9)

9 (8-10)



34.86 (1.66)

33.93 (1.17)

39.84 (0.85)


Variances analyses comparison of the RMS among measurements (Table 2)

demonstrated a significant difference (F(5,108)= 56.69; p<0.001). The post hoc multiple

comparisons (Holm-Sidak Method) showed that in the PT-KAN Group the RMS was

greater at 48h (p=0.004) and at age equivalent to term (p=0.004) compared with the

measurement at 0h, but there is no statistically significant difference between the




T Group (p=0.004).

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muscle in preterm newborns in kangaroo position or not and in term newborns.

Intervals between

measurements

Groups

PT-KAN

(��± DP)

PT-NKAN

(��± DP)

T

(��± DP)

0h

31.85±6.93

37.59±4.42

-

48h

49.30±4.91

38.17±3.10

-

TEA and TA

48.03±5.56

-

27.12±5.70


newborns not in kangaroo position. T: group of term newborns. TEA: term equivalent age (for PT-KAN group).

TA: term age (for T group). *Analysis of variance for repeated measurements: F(5,108)= 56.69; p<0.001. Multiple

comparisons (Holm-Sidak Test): in the PT-KAN group: 0h x 48h (p=0.004), 0h x TEA (p=0.004). Between PT-

KAN and T groups: TEA x TA (p=0.004).

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DISCUSSION


brachial biceps muscle in preterm newborns maintained in a kangaroo care environment

for 48h even when placed on kangaroo position during only to 8 – 12h by day, which


changes myoelectrical activity in these newborn, at least in the case of the flexor muscle

evaluated here.



24h in kangaroo position saw an increase in the myoelectrical activity of flexor muscles

and this increase persisted even after 24h out of this position.



the brachial biceps muscle during 96h in kangaroo position. As in our study, these

authors observed this effect 48h after being placed in kangaroo position. However, it is

important to note the presence of a control group in our study which gives added weight

to our results. Also in accordance with the findings of Diniz et al16

, the effect on



age equivalent to term, was significantly greater than that in term newborns, although a


be associated with the fact that preterm newborns received extra-uterine stimuli up to

age equivalent to term, especially those provided by the kangaroo position. However,

the term newborns to not have the opportunity to receive such stimuli.

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using transcranial magnetic stimulation, showed that




the brain mature faster in health preterm newborns. These findings are relevant, since

changes in the myoelectrical parameter in response to kangaroo position found in our

study may be associated with faster maturation of the brain and better performance of

the cerebral structures controlling motor activity. The mechanism behind this central

motor activation on the peripheral myoelectrical response is still a matter of debate, but

it corroborates the conclusion that the kangaroo position has an effect on muscle

response.




analysis26






preterm newborns. This hypothesis may be sustained by the characteristics of the

kangaroo position, which provide different stimuli for the newborn. However, given

that, in the kangaroo position, the preterm newborn remains in skin-to-skin contact with

the adult chest, with its limbs flexed, in a vertical position1 receiving various

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environmental inputs, the sensory, postural and vestibular stimuli furnished when in this

position16

may cause a considerable increase in motor activity. This evidence suggests

that the kangaroo position has a positive influence on motor activity in newborns that is

physiologically represented by an alteration in myoelectrical parameters as observed

here. Moreover, myoelectrical alterations in a flexor muscle are a relevant physiological

response, since the kangaroo position involves maintaining a flexed posture.



whether the increase in electromyographic activity in the preterm newborns at age

equivalent to term is only related to the growth and development of the neonates and not

the influence of the kangaroo position. However, the reduced myoelectrical response in

group T suggests that it is the kangaroo position and not the growth of the newborns per

se that is responsible for the changes in electromyographic activity observed here. Apart

from this limitation, the sample size was lower than the estimate so it is a factor that

may diminish the reliability of our findings. However with a sample power of 90%, the


support our inferences.

In conclusion, although this is a preliminary study their results provide evidence

that the kangaroo position in the short term induces an increase in myoelectrical activity

in preterm newborns which persists until the age equivalent to term. In addition, it may

be that the fact that electromyographic activity in premature newborn at age equivalent

to term is greater than that of term newborns is related to the different stimuli (tactile,

synesthetic and vestibular) that they receive. It is thus suggested that this intervention

induces changes in the flexor function of the muscle (flexor tonus), thereby making it

possible to influence the motor development of the newborn. The age to which (in the

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long term) these effects persist and whether they are positive effects need to be

examined in further studies.



activity in newborn in kangaroo position. It is suggested that further research be carried

out to investigate the electromyographic effect of the kangaroo position on other

muscles involved in the postural system, in both term and preterm newborns.

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Ethics approval: IMIP’s Ethics Committee for Research involving Human Beings

(protocol no.1902)


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16

REFERENCES








4. Johnston C, Campbell-Yeo M, Fernandes A, Inglis D, Streiner D, Zee R. Skin-to-skin

care for procedural pain in neonates. Cochrane Database Syst Rev. 2014 (4):CD008435.















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21:601-5.






Rev 2013;(6):CD002771.





2013; 13:79.






Kinesiol 2000;10:361-74.



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22:444–46.



(Rio J) 2006;82:475–80.

















001814.

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STROBE Statement—checklist of items that should be included in reports of observational studies

Item

No Recommendation

Title and abstract 1 The study’s design with a commonly used term in the title: Electromyographic

activity of preterm newborns in kangaroo position: a cohort study.

The abstract has an informative and balanced summary of what was done and what

was found in the search.

Introduction

Background/rationale 2 A scientific and rational background for the research reported was used.

Objectives 3 Specific objectives and were prespecified hypotheses: The aim of this study was thus

to compare electromyographic activity in preterm newborns in kangaroo position with

the activity of newborns not placed in this position.

Methods

Study design 4 A cohort study was carried out.

Setting 5 Been described in the setting, locations / dates, including periods of recruitment,

exposure, follow-up and data collection

Participants 6 Cohort study - have been described: the eligibility criteria, and the sources and

methods of selection of participants; yet the methods of follow-up.

Variables 7 Were all clearly defined outcomes, exposures, predictors, potential confounders and

effect modifiers.

Data sources/

measurement

8 Surface electromyography (EMGs) was used to investigate muscle activity in the

brachial biceps at rest. Three groups were designed: 1) preterm newborns in kangaroo

position (PT – KAN), its electromyographic activity being recorded at 0h

(immediately before starting this position), and then at 48h from beginning the

position (but newborns being kept in the kangaroo position for 8-12 hours per day)

and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not in kangaroo

position (PT – NKAN), the measurements being made at 0h and 48h; and 3) term

newborns (T), in which measurements were made at 24h of chronological age.

Bias 9 However, the reduced myoelectrical response in group T suggests that it is the

kangaroo position and not the growth of the newborns per se that is responsible for the

changes in electromyographic activity observed here. Apart from this limitation, the

sample size was lower than the estimate so it is a factor that may diminish the

reliability of our findings. However with a sample power of 90%, the large differences

found between the means and the statistically significant figures may support our

inferences.

Study size 10 A non-probabilistic convenient sample of newborns was selected, the size of the

sample being based on a previous study 17 that found variance of 2.6 in

electromyographic activity and estimated the minimum difference between means to

be 2 µV. With an alpha error of 0.05 and power of 90%, 21 individuals were

calculated for each group.

Quantitative variables 11 For analysis of muscle activity the signal was transformed into the Root Mean Square

(RMS) and normalized.20,21

For normalization, 100% corresponding to the maximum

peak electromyographic signal was taken as a reference. A period of 10s of the total

electromyographic reading (30s) was used.

Statistical methods 12 Comparison of the means of the groups was carried out after verifying the normality

of the distribution (Kolmogorov-Smirnov Test) and the homogeneity of variance

(Levene Test), by analysis of variance for repeated measurements, followed by



Continued on next page

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Results

Participants 13 A cohort study was carried out, between July 2012 and January 2013, at the Instituto de

Medicina Integral Prof. Fernando Figueira (IMIP), in Recife, Brazil, with 64 hospitalized

newborns, from which 38 preterm in the Kangaroo Unit sector and 26 term in the Nursery

sector of the IMIP hospital.

Three groups were designed: Group 1 (n=25): preterm newborns in kangaroo position (PT –

KAN); 2) Group 2 (n=13): preterm newborns not in kangaroo position (PT – NKAN); and 3)

Group 3 (n=16): term newborns (T).

Descriptive data 14 The clinical and biological characteristics of the newborns in each group can be seen in

Table 1.

The newborns were kept in the kangaroo position for 8-12 hours per day, until the evaluation

after 48h.

Outcome data 15 In the PT – KAN group, electromyographic activity was first recorded before neonate being

in kangaroo position (0h). Immediately after taking this record, the neonates were placed for

the first time in the kangaroo position. The kangaroo position adopted was that

recommended by the Kangaroo Unit, in which the newborn is positioned against the adult’s

chest, face down, wrapped in a strip of flexible cloth. Subsequent recordings were taken

immediately after 48h of the kangaroo position and, finally, at term-equivalent age (40 ± 1

weeks). The newborns were kept in the kangaroo position for 8-12 hours per day, until the


In the PT – NKAN group the measurements were made at 0h and 48h. In the T group

electromyographic activity was measured only once, at a chronological age until 24h.

Main results and

Other analyses

16 Variances analyses comparison of the RMS among measurements (Table 2) demonstrated a

significant difference (F(5,108)= 56.69; p<0.001). The post hoc multiple comparisons (Holm-

Sidak Method) showed that in the PT-KAN Group the RMS was greater at 48h (p=0.004)

and at age equivalent to term (p=0.004) compared with the measurement at 0h, but there is

no statistically significant difference between the measurements at 48h and at age equivalent

to term. In the PT-NKAN group no significant difference was found between 0h and 48h.

The RMS in the PT-KAN group at age equivalent to term was greater than in the T Group

(p=0.004).

Discussion

Key results 17 The results were discussed based on current references.

Limitations 18 One limitation of the present study is the absence of a group of preterm newborns not in

kangaroo care followed up to age equivalent to term, as this would shed light on whether the

increase in electromyographic activity in the preterm newborns at age equivalent to term is

only related to the growth and development of the neonates and not the influence of the

kangaroo position. However, the reduced myoelectrical response in group T suggests that it

is the kangaroo position and not the growth of the newborns per se that is responsible for the

changes in electromyographic activity observed here. Apart from this limitation, the sample

size was lower than the estimate so it is a factor that may diminish the reliability of our

findings. However with a sample power of 90%, the large differences found between the

means and the statistically significant figures may support our inferences.

Interpretation 19 An overall cautious interpretation of the results was performed, considering objectives,

limitations, multiplicity of analyzes, results from similar studies, and other relevant evidence.

Generalisability 20 The generalization (external validity) of study results was discussed

Other information

Funding 21 The source of funding and the role of the funders for the study is described in the article.

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Electromyographic activity of preterm newborns in kangaroo position: a cohort study

Journal: BMJ Open

Manuscript ID: bmjopen-2014-005560.R2


Date Submitted by the Author: 02-Sep-2014



Paediatrics




BMJ Open on 13 F


http://bmjopen.bm

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BM



ownloaded from



1


study



3; Geisy Maria


5.







[email protected].



Word count: 3676

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ABSTRACT

Objective: to compare the electromyographic activity of preterm newborns placed in

kangaroo position with the activity of newborns not placed in this position.

Design: A cohort study.

Setting: A Kangaroo Unit sector and Nursery sector in a secondary and tertiary care at a

mother-child hospital in Recife, Brazil.

Participants: Preterm infants of gestational age of 27 to 34 weeks (n=38) and term

infants (n=39).

Primary and secondary outcome measures: Surface electromyography (EMGs) was

used to investigate muscle activity in the brachial biceps at rest. Three groups were

designed: 1) preterm newborns in kangaroo position (PT – KAN), whereas the newborn

remains in a vertical position, lying face down, with limbs flexed, dressed in light

clothes, maintaining skin-to-skin contact with the adult’s thorax. Her electromyographic

activity was recorded at 0h (immediately before starting this position), and then at 48h

after the beginning of the position (but newborns were kept in the kangaroo position for

8-12 hours per day) and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not

in kangaroo position (PT – NKAN), the measurements were made at 0h and 48h; and 3)


Results: The Root Mean Square (RMS) values showed significant differences among

the groups (F(5,108)= 56.69; p<0.001). The multiple comparisons showed that, RMS was

greater at 48h compared to 0h in the preterm group in kangaroo position, but not in the

group not submitted to kangaroo position. The RMS in the term equivalent aged group

in the kangaroo position was also greater when compared those at the term group.

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term.

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position.


may diminish the reliability of our findings. However the sample power of 90%, the

large differences found between the means and the statistically significant results may


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INTRODUCTION

The Kangaroo Method (KM) is a kind of intervention that aims to improve the

health of low-weight preterm newborns.1 There is evidence that the method provides

various benefits. These benefits include an increase in body temperature,2,3

stabilization

of cardio-respiratory frequency,3,4

improved brain oxygenation,5

behavior improvement

(crying and sleep),6-8

pain reduction4,9,10

and greater adherence and duration of

breastfeeding.11-13


mortality,14,15

infections14

and hospital stay.15


remains in a vertical position, with limbs flexed, dressed in light clothes, maintaining

skin-to-skin contact and the face on with the adult’s thorax1. This position allows the

neonates to receive sensory, vestibular and postural stimuli and the effects on the motor

responses in the newborns has thus aroused some interest among investigators.16



preterm newborns after different periods of time in the kangaroo position (up to 96h)

and this increase persists until an age equivalent to term. These results were pioneering,

although no study has yet been conducted in which these responses have been compared

with those of preterm newborns not in kangaroo position and those of term newborns.

The aim of the present study was thus to compare electromyographic activity in preterm

newborns in kangaroo position and the activity of newborns not placed in this position.

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METHODS

Participants

This cohort study was carried out between July 2012 and January 2013, at the


hospitalized newborns, 38 preterm were in the Kangaroo Unit sector and 26 terms were

in the Nursery sector at IMIP hospital.


and has a ward with



peripheric oxygen saturation of over 89%, absence of signs of respiratory distress, signs

cyanosis or pallor and pain) The newborns had to tolerate food, to breathe without the

use of any equipment and weigh more than 1,250 grams.


therapy and physiotherapy. In this unit, the newborns, referred to medical services, are

evaluated and undergo to an early stimulation program.


27 to 34 weeks and a corrected age of until 35 weeks at the time of the first

electromyographic examination, and had not previously been in the kangaroo position.


weeks. Neonates were only included when their Brazelton state during




transfontanelar ultra-sound and included in the medical records), seizures, congenital

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All these inclusion and exclusion factors were evaluated using collected data

from patients’ medical records evaluated by neonatologists at the Neonatal Intensive

Care Unit, the Kangaroo Unit sector and the Nursery sector.

A convenient non-probabilistic sequential sample was obtained from the

newborns. The size of the sample was calculated based on a previous study 17

that found

variance of 2.6 in the electromyographic activity and estimated the minimum difference

between means of 2 µV. With an alpha error of 0.05 and the power of 90%, the sample

size result was 21 individuals for each group.


Research involving Human Beings and was approved (protocol number 1902). The

parents or guardians who agreed to participate in the study signed the free informed

consent.




and a self-adhesive 4.2 mm diameter Ag/AgCl electrode (Meditrace 100®

) were used to

connect the equipment to the newborn’s body at examination. The electromyograph was

connected to a laptop using Myographic 2.0 software (Miotec Equipamentos

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Biomédicos - Brazil) to process the myoelectrical records. The sampling frequency was

2000 Hz and the electromyograms were amplified 2000 times.





project.18

The electrodes were adjusted to ensure the distance between them could not

exceed more than 20 mm and the reference electrode was always placed on the lateral

malleolus contralateral to the muscle under evaluation.

Before the measurements were performed, the newborn was placed on a small

wedge-shaped cushion at an angle of 30° relative to the horizontal plane. The

electromyographic activity captured the newborns in Brazelton state 4 or 5 (inactive

alert or alert with activity), respectively.19

There were three designed groups: Group 1 (n=25): preterm newborns in the

kangaroo position (PT – KAN); 2) Group 2 (n=13): preterm newborns not submitted in

kangaroo position (PT – NKAN); and 3) Group 3 (n=16): term newborns (T).

In the PT – KAN group, electromyographic activity was first recorded before the

neonates were in the kangaroo position (0h). Immediately after taking this record, the


adopted was as recommended by the Kangaroo Unit, in which the newborn is

positioned in the adult’s breasts, face down, should be dressed in light clothes and

wrapped in a flexible cloth. Subsequent recordings were taken immediately after 48h of

the kangaroo position and, finally, at term-equivalent age (40 ± 1 weeks). The newborns

were kept in the kangaroo position for 8-12 hours per day until the evaluation after

48h. The newborns were removed from the Kangaroo Position (and placed on a soft

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9

cushion) for short intervals when the mothers would go to the restroom or to take a

shower, during breastfeeding or other forms of feeding.

The measurements in the PT – NKAN group were made at 0h and 48h. In the T

group of electromyographic activity was measured only once at a chronological age of

until 24h.



motor stimulation during data collection, except for oral stimulation done by speech

therapists, when it was necessary.


The muscle activity analysis signal was transformed to the Root Mean Square


For normalization, 100% corresponded to the maximum

peak of the electromyographic signal was taken as a reference. A period of 10s of total


The comparison of means of the groups was carried out after verifying the


variance (Levene Test), by repeated measurements analysis of variance, followed by



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RESULTS

The clinical and biological characteristics of the newborns in each group are

presented in Table 1.


PT-KAN

(n= 25)

PT-NKAN

(n=13)

T

(n=26)





max)

9 (7-10)

9 (7-9)

9 (8-10)



34.86 (1.66)

33.93 (1.17)

39.84 (0.85)

For continuous variables, the mean (SD) is given; for ordinal variables (Apgar), the median (min-max).

The comparison on variances analyses of the RMS among measurements (Table

2) demonstrated a significant difference (F(5,108)= 56.69; p<0.001). The post hoc

multiple comparisons (Holm-Sidak Method) showed that in the PT-KAN Group, the

RMS was greater at 48h (p=0.004) and age equivalent to term measurement was

(p=0.004) compared with the measurement at 0h, but there is no statistically significant

difference between the measurements at 48h and age equivalent to term. In the PT-

NKAN group no significant difference was found between 0h and 48h.


T Group (p=0.004).

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muscle in preterm newborns in the kangaroo position or not and in term

newborns.

Intervals between

measurements

Groups

PT-KAN

(��± DP)

PT-NKAN

(��± DP)

T

(��± DP)

0h

31.85±6.93

37.59±4.42

-

48h

49.30±4.91

38.17±3.10

-

TEA and TA

48.03±5.56

-

27.12±5.70

RMS: Root Mean Square. PT-KAN: preterm newborns in the kangaroo position. PT-NKAN: preterm newborns

not in the kangaroo position. T: term newborns. TEA: term equivalent age (for PT-KAN group). TA: term age (for

T group). *Analysis of variance for repeated measurements: F(5,108)= 56.69; p<0.001. Multiple comparisons

(Holm-Sidak Test): in the PT-KAN group: 0h x 48h (p=0.004), 0h x TEA (p=0.004). Between PT-KAN and T

groups: TEA x TA (p=0.004).

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DISCUSSION


brachial biceps muscle in preterm newborns maintained at a kangaroo care environment

for 48h even when placed in the kangaroo position during 8 – 12h per day, which this


changes myoelectrical activity in these newborns, at least in the flexor muscle case

evaluated here.



24h in the kangaroo position had an increase in the myoelectrical activity of flexor

muscles and this increase persisted even after 24h out of this position.

In later study, Diniz et al16

observed a growing increase in electromyographic

activity in the brachial biceps muscle during 96h in the kangaroo position. As in our

study, was observed this effect 48h after being placed in kangaroo position. However, it

is important to note the presence of the control group in our study which added weight

to our results. Also in accordance to of Diniz et al16

findings, the effect on



age equivalent to term, was significantly greater than in term newborns, although a


be associated to the fact that preterm newborns received extra-uterine stimuli at age

equivalent to term, especially those provided by the kangaroo position. However, the

term newborns do not have the opportunity to receive such stimuli.

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The effect of the kangaroo position in inducing a more flexed posture in preterm


and this also suggests a specific effect of the kangaroo



used transcranial magnetic stimulation, showing that

preterm newborns underwent the kangaroo method had better connectivity and synaptic

efficacy of the motor routes in the brain at adolescence. Another study25

provided

electroencephalic evidence to the effect that the kangaroo interventions makes the brain

mature faster in healthy preterm newborns. These findings are relevant, since changes in

the myoelectrical parameter in response to the kangaroo position found in our study

may be associated with faster maturation of the brain and better performance of the

cerebral structures controlling motor activity. The mechanism behind this central motor

activation on the peripheral myoelectrical response is still a matter to study, but it

corroborates the conclusion that the kangaroo position has an effect on the muscle

response.




analysis26



and vestibular stimuli may influence the motor abilities of the newborns.27,28



preterm newborns. This hypothesis may be sustained by the characteristics on the

kangaroo position, which provide different stimuli for the newborn. Therefore,

considering that, in the kangaroo position the preterm newborn remains in skin-to-skin

contact with the adult breast, with its limbs flexed, in a vertical position1 and receiving

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various environmental inputs, such as sensory, postural and vestibular stimuli, the

kangaroo position16

may causing a considerable increase in motor activity. This

evidence suggests that the kangaroo position has a positive influence on the motor

activity in newborns that is physiologically represented by an alteration in the

myoelectrical parameters as observed here. Moreover, the myoelectrical alterations in

the flexor muscle are a relevant physiological response, since the kangaroo position

maintains a flexed posture.

One limitation on this present study is the absence of PT-NKAN (preterm

newborns not submitted in kangaroo position) followed up to age equivalent to term.

Such fact could clarify whether the increased electromyographic activity in PT-KAN

(preterm newborns in the kangaroo position) group at age equivalent to term is only

related to the growth and development of the neonates or the influence of the kangaroo

position. However, the reduced myoelectrical response in T group suggests that it is the


changes in the electromyographic activity observed here. Apart from this limitation, the

sample size was lower than the estimate so it is a factor that may diminish the reliability

of our findings. However with a sample power of 90%, the large differences found

between the means and statistically significant results may support our inferences.

In conclusion, although this is a preliminary study resulting to provide evidence

that the kangaroo position in short term induces an increase in the myoelectrical activity

in the preterm newborns which persists until the age equivalent to term. In addition, it

may be the fact that electromyographic activity in premature newborn at age equivalent

to term is greater than the term newborns and related to the different stimuli (tactile,

synesthetic and vestibular) that they have received. It is suggested that this intervention

induces changes in the flexor muscle function (flexor tonus), thereby making it possible

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to influence the motor development of the newborns. The age to which (in long terms)

these effects persist and whether they have positive effects need to be examined in

further studies.



activity in newborns in the kangaroo position. It is suggested that further research

should be carried out to investigate the electromyographic effect of the kangaroo

position on other muscles involved in the postural system, both in newborns preterms

such as in term newborns.

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Acknowledgements: We wish to thank the babies, parents and, especially, the nursing

technicians at the Kangaroo Unit at the Instituto de Medicina Integral Prof. Fernando

Figueira (IMIP), Recife – Brazil.












Acknowledgements: We wish to thank the babies, parents and, especially, the

nursing technicians at the Kangaroo Unit at the Instituto de Medicina Integral Prof.

Fernando Figueira (IMIP), Recife – Brazil. We would also like to thank the

translators Patricia Ferraz and Peter Ratclisse (Sharing English Traduções) , by

editing the text in the English language.

Funding Source: Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco –

FACEPE (APQ – 0552–4.08/100) and Fundo de Apoio à Pesquisa e Ensino do IMIP (FAPE-IMIP).

Financial Disclosure: Miranda RM was supported by the post graduate scholarship

from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and

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Diniz KT was supported by the post graduate scholarship from Fundação de Amparo à

Ciência e Tecnologia do Estado de Pernambuco (FACEPE).


Ethics approval: Ethics Committee for Research involving Human Beings at IMIP

(protocol number1902)


REFERENCES








4. Johnston C, Campbell-Yeo M, Fernandes A, et al. Skin-to-skin care for procedural

pain in neonates. Cochrane Database Syst Rev. 2014 (4):CD008435.








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21:601-5.






Rev 2013;(6):CD002771.





2013; 13:79.

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Kinesiol 2000;10:361-74.







22:444–46.



(Rio J) 2006;82:475–80.










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001814.

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1


study



3; Geisy Maria


5.







[email protected].



Word count: 3676

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ABSTRACT

Objective: to compare the electromyographic activity of preterm newborns placed in

kangaroo position with the activity of newborns not placed in this position.

Design: A cohort study.

Setting: A Kangaroo Unit sector and Nursery sector in a secondary and tertiary care at a

mother-child hospital in Recife, Brazil.

Participants: Preterm infants of gestational age of 27 to 34 weeks (n=38) and term

infants (n=39).

Primary and secondary outcome measures: Surface electromyography (EMGs) was

used to investigate muscle activity in the brachial biceps at rest. Three groups were

designed: 1) preterm newborns in kangaroo position (PT – KAN), whereas the newborn

remains in a vertical position, lying face down, with limbs flexed, dressed in light

clothes, maintaining skin-to-skin contact with the adult’s thorax. Her electromyographic

activity was recorded at 0h (immediately before starting this position), and then at 48h

after the beginning of the position (but newborns were kept in the kangaroo position for

8-12 hours per day) and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not

in kangaroo position (PT – NKAN), the measurements were made at 0h and 48h; and 3)


Results: The Root Mean Square (RMS) values showed significant differences among

the groups (F(5,108)= 56.69; p<0.001). The multiple comparisons showed that, RMS was

greater at 48h compared to 0h in the preterm group in kangaroo position, but not in the

group not submitted to kangaroo position. The RMS in the term equivalent aged group

in the kangaroo position was also greater when compared those at the term group.

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term.

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position.


may diminish the reliability of our findings. However the sample power of 90%, the

large differences found between the means and the statistically significant results may


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INTRODUCTION

The Kangaroo Method (KM) is a kind of intervention that aims to improve the

health of low-weight preterm newborns.1 There is evidence that the method provides

various benefits. These benefits include an increase in body temperature,2,3

stabilization

of cardio-respiratory frequency,3,4

improved brain oxygenation,5

behavior improvement

(crying and sleep),6-8

pain reduction4,9,10

and greater adherence and duration of

breastfeeding.11-13


mortality,14,15

infections14

and hospital stay.15


remains in a vertical position, with limbs flexed, dressed in light clothes, maintaining

skin-to-skin contact and the face on with the adult’s thorax1. This position allows the

neonates to receive sensory, vestibular and postural stimuli and the effects on the motor

responses in the newborns has thus aroused some interest among investigators.16



preterm newborns after different periods of time in the kangaroo position (up to 96h)

and this increase persists until an age equivalent to term. These results were pioneering,

although no study has yet been conducted in which these responses have been compared

with those of preterm newborns not in kangaroo position and those of term newborns.

The aim of the present study was thus to compare electromyographic activity in preterm

newborns in kangaroo position and the activity of newborns not placed in this position.

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METHODS

Participants

This cohort study was carried out between July 2012 and January 2013, at the


hospitalized newborns, 38 preterm were in the Kangaroo Unit sector and 26 terms were

in the Nursery sector at IMIP hospital.


and has a ward with



peripheric oxygen saturation of over 89%, absence of signs of respiratory distress, signs

cyanosis or pallor and pain) The newborns had to tolerate food, to breathe without the

use of any equipment and weigh more than 1,250 grams.


therapy and physiotherapy. In this unit, the newborns, referred to medical services, are

evaluated and undergo to an early stimulation program.


27 to 34 weeks and a corrected age of until 35 weeks at the time of the first

electromyographic examination, and had not previously been in the kangaroo position.


weeks. Neonates were only included when their Brazelton state during




transfontanelar ultra-sound and included in the medical records), seizures, congenital

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All these inclusion and exclusion factors were evaluated using collected data

from patients’ medical records evaluated by neonatologists at the Neonatal Intensive

Care Unit, the Kangaroo Unit sector and the Nursery sector.

A convenient non-probabilistic sequential sample was obtained from the

newborns. The size of the sample was calculated based on a previous study 17

that found

variance of 2.6 in the electromyographic activity and estimated the minimum difference

between means of 2 µV. With an alpha error of 0.05 and the power of 90%, the sample

size result was 21 individuals for each group.


Research involving Human Beings and was approved (protocol number 1902). The

parents or guardians who agreed to participate in the study signed the free informed

consent.




and a self-adhesive 4.2 mm diameter Ag/AgCl electrode (Meditrace 100®

) were used to

connect the equipment to the newborn’s body at examination. The electromyograph was

connected to a laptop using Myographic 2.0 software (Miotec Equipamentos

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Biomédicos - Brazil) to process the myoelectrical records. The sampling frequency was

2000 Hz and the electromyograms were amplified 2000 times.





project.18

The electrodes were adjusted to ensure the distance between them could not

exceed more than 20 mm and the reference electrode was always placed on the lateral

malleolus contralateral to the muscle under evaluation.

Before the measurements were performed, the newborn was placed on a small

wedge-shaped cushion at an angle of 30° relative to the horizontal plane. The

electromyographic activity captured the newborns in Brazelton state 4 or 5 (inactive

alert or alert with activity), respectively.19

There were three designed groups: Group 1 (n=25): preterm newborns in the

kangaroo position (PT – KAN); 2) Group 2 (n=13): preterm newborns not submitted in

kangaroo position (PT – NKAN); and 3) Group 3 (n=16): term newborns (T).

In the PT – KAN group, electromyographic activity was first recorded before the

neonates were in the kangaroo position (0h). Immediately after taking this record, the


adopted was as recommended by the Kangaroo Unit, in which the newborn is

positioned in the adult’s breasts, face down, should be dressed in light clothes and

wrapped in a flexible cloth. Subsequent recordings were taken immediately after 48h of

the kangaroo position and, finally, at term-equivalent age (40 ± 1 weeks). The newborns

were kept in the kangaroo position for 8-12 hours per day until the evaluation after

48h. The newborns were removed from the Kangaroo Position (and placed on a soft

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9

cushion) for short intervals when the mothers would go to the restroom or to take a

shower, during breastfeeding or other forms of feeding.

The measurements in the PT – NKAN group were made at 0h and 48h. In the T

group of electromyographic activity was measured only once at a chronological age of

until 24h.



motor stimulation during data collection, except for oral stimulation done by speech

therapists, when it was necessary.


The muscle activity analysis signal was transformed to the Root Mean Square


For normalization, 100% corresponded to the maximum

peak of the electromyographic signal was taken as a reference. A period of 10s of total


The comparison of means of the groups was carried out after verifying the


variance (Levene Test), by repeated measurements analysis of variance, followed by



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RESULTS

The clinical and biological characteristics of the newborns in each group are

presented in Table 1.


PT-KAN

(n= 25)

PT-NKAN

(n=13)

T

(n=26)





max)

9 (7-10)

9 (7-9)

9 (8-10)



34.86 (1.66)

33.93 (1.17)

39.84 (0.85)

For continuous variables, the mean (SD) is given; for ordinal variables (Apgar), the median (min-max).

The comparison on variances analyses of the RMS among measurements (Table

2) demonstrated a significant difference (F(5,108)= 56.69; p<0.001). The post hoc

multiple comparisons (Holm-Sidak Method) showed that in the PT-KAN Group, the

RMS was greater at 48h (p=0.004) and age equivalent to term measurement was

(p=0.004) compared with the measurement at 0h, but there is no statistically significant

difference between the measurements at 48h and age equivalent to term. In the PT-

NKAN group no significant difference was found between 0h and 48h.


T Group (p=0.004).

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muscle in preterm newborns in the kangaroo position or not and in term

newborns.

Intervals between

measurements

Groups

PT-KAN

(��± DP)

PT-NKAN

(��± DP)

T

(��± DP)

0h

31.85±6.93

37.59±4.42

-

48h

49.30±4.91

38.17±3.10

-

TEA and TA

48.03±5.56

-

27.12±5.70

RMS: Root Mean Square. PT-KAN: preterm newborns in the kangaroo position. PT-NKAN: preterm newborns

not in the kangaroo position. T: term newborns. TEA: term equivalent age (for PT-KAN group). TA: term age (for

T group). *Analysis of variance for repeated measurements: F(5,108)= 56.69; p<0.001. Multiple comparisons

(Holm-Sidak Test): in the PT-KAN group: 0h x 48h (p=0.004), 0h x TEA (p=0.004). Between PT-KAN and T

groups: TEA x TA (p=0.004).

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DISCUSSION


brachial biceps muscle in preterm newborns maintained at a kangaroo care environment

for 48h even when placed in the kangaroo position during 8 – 12h per day, which this


changes myoelectrical activity in these newborns, at least in the flexor muscle case

evaluated here.



24h in the kangaroo position had an increase in the myoelectrical activity of flexor

muscles and this increase persisted even after 24h out of this position.

In later study, Diniz et al16

observed a growing increase in electromyographic

activity in the brachial biceps muscle during 96h in the kangaroo position. As in our

study, was observed this effect 48h after being placed in kangaroo position. However, it

is important to note the presence of the control group in our study which added weight

to our results. Also in accordance to of Diniz et al16

findings, the effect on



age equivalent to term, was significantly greater than in term newborns, although a


be associated to the fact that preterm newborns received extra-uterine stimuli at age

equivalent to term, especially those provided by the kangaroo position. However, the

term newborns do not have the opportunity to receive such stimuli.

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The effect of the kangaroo position in inducing a more flexed posture in preterm


and this also suggests a specific effect of the kangaroo



used transcranial magnetic stimulation, showing that

preterm newborns underwent the kangaroo method had better connectivity and synaptic

efficacy of the motor routes in the brain at adolescence. Another study25

provided

electroencephalic evidence to the effect that the kangaroo interventions makes the brain

mature faster in healthy preterm newborns. These findings are relevant, since changes in

the myoelectrical parameter in response to the kangaroo position found in our study

may be associated with faster maturation of the brain and better performance of the

cerebral structures controlling motor activity. The mechanism behind this central motor

activation on the peripheral myoelectrical response is still a matter to study, but it

corroborates the conclusion that the kangaroo position has an effect on the muscle

response.




analysis26



and vestibular stimuli may influence the motor abilities of the newborns.27,28



preterm newborns. This hypothesis may be sustained by the characteristics on the

kangaroo position, which provide different stimuli for the newborn. Therefore,

considering that, in the kangaroo position the preterm newborn remains in skin-to-skin

contact with the adult breast, with its limbs flexed, in a vertical position1 and receiving

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various environmental inputs, such as sensory, postural and vestibular stimuli, the

kangaroo position16

may causing a considerable increase in motor activity. This

evidence suggests that the kangaroo position has a positive influence on the motor

activity in newborns that is physiologically represented by an alteration in the

myoelectrical parameters as observed here. Moreover, the myoelectrical alterations in

the flexor muscle are a relevant physiological response, since the kangaroo position

maintains a flexed posture.

One limitation on this present study is the absence of PT-NKAN (preterm

newborns not submitted in kangaroo position) followed up to age equivalent to term.

Such fact could clarify whether the increased electromyographic activity in PT-KAN

(preterm newborns in the kangaroo position) group at age equivalent to term is only

related to the growth and development of the neonates or the influence of the kangaroo

position. However, the reduced myoelectrical response in T group suggests that it is the


changes in the electromyographic activity observed here. Apart from this limitation, the

sample size was lower than the estimate so it is a factor that may diminish the reliability

of our findings. However with a sample power of 90%, the large differences found

between the means and statistically significant results may support our inferences.

In conclusion, although this is a preliminary study resulting to provide evidence

that the kangaroo position in short term induces an increase in the myoelectrical activity

in the preterm newborns which persists until the age equivalent to term. In addition, it

may be the fact that electromyographic activity in premature newborn at age equivalent

to term is greater than the term newborns and related to the different stimuli (tactile,

synesthetic and vestibular) that they have received. It is suggested that this intervention

induces changes in the flexor muscle function (flexor tonus), thereby making it possible

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to influence the motor development of the newborns. The age to which (in long terms)

these effects persist and whether they have positive effects need to be examined in

further studies.



activity in newborns in the kangaroo position. It is suggested that further research

should be carried out to investigate the electromyographic effect of the kangaroo

position on other muscles involved in the postural system, both in newborns preterms

such as in term newborns.

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Acknowledgements: We wish to thank the babies, parents and, especially, the nursing

technicians at the Kangaroo Unit at the Instituto de Medicina Integral Prof. Fernando

Figueira (IMIP), Recife – Brazil.














Financial Disclosure: Miranda RM was supported by the post graduate scholarship

from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and

Diniz KT was supported by the post graduate scholarship from Fundação de Amparo à

Ciência e Tecnologia do Estado de Pernambuco (FACEPE).


Ethics approval: Ethics Committee for Research involving Human Beings at IMIP

(protocol number1902)


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REFERENCES








4. Johnston C, Campbell-Yeo M, Fernandes A, Inglis D, Streiner D, Zee R. Skin-to-skin

care for procedural pain in neonates. Cochrane Database Syst Rev. 2014 (4):CD008435.















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21:601-5.






Rev 2013;(6):CD002771.





2013; 13:79.






Kinesiol 2000;10:361-74.



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22:444–46.



(Rio J) 2006;82:475–80.

















001814.

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STROBE Statement—checklist of items that should be included in reports of observational studies

Item

No Recommendation

Title and abstract 1 The study’s design with a commonly used term in the title: Electromyographic

activity of preterm newborns in kangaroo position: a cohort study.

The abstract has an informative and balanced summary of what was done and what

was found in the search.

Introduction

Background/rationale 2 A scientific and rational background for the research reported was used.

Objectives 3 Specific objectives and were prespecified hypotheses: The aim of this study was thus

to compare electromyographic activity in preterm newborns in kangaroo position with

the activity of newborns not placed in this position.

Methods

Study design 4 A cohort study was carried out.

Setting 5 Been described in the setting, locations / dates, including periods of recruitment,

exposure, follow-up and data collection

Participants 6 Cohort study - have been described: the eligibility criteria, and the sources and

methods of selection of participants; yet the methods of follow-up.

Variables 7 Were all clearly defined outcomes, exposures, predictors, potential confounders and

effect modifiers.

Data sources/

measurement

8 Surface electromyography (EMGs) was used to investigate muscle activity in the

brachial biceps at rest. Three groups were designed: 1) preterm newborns in kangaroo

position (PT – KAN), its electromyographic activity being recorded at 0h

(immediately before starting this position), and then at 48h from beginning the

position (but newborns being kept in the kangaroo position for 8-12 hours per day)

and at term equivalent age (40 ± 1 weeks); 2) preterm newborns not in kangaroo

position (PT – NKAN), the measurements being made at 0h and 48h; and 3) term

newborns (T), in which measurements were made at 24h of chronological age.

Bias 9 However, the reduced myoelectrical response in group T suggests that it is the


changes in electromyographic activity observed here. Apart from this limitation, the

sample size was lower than the estimate so it is a factor that may diminish the

reliability of our findings. However with a sample power of 90%, the large differences

found between the means and the statistically significant figures may support our

inferences.

Study size 10 A non-probabilistic convenient sample of newborns was selected, the size of the

sample being based on a previous study 17 that found variance of 2.6 in

electromyographic activity and estimated the minimum difference between means to

be 2 µV. With an alpha error of 0.05 and power of 90%, 21 individuals were

calculated for each group.

Quantitative variables 11 For analysis of muscle activity the signal was transformed into the Root Mean Square


For normalization, 100% corresponding to the maximum

peak electromyographic signal was taken as a reference. A period of 10s of the total


Statistical methods 12 Comparison of the means of the groups was carried out after verifying the normality

of the distribution (Kolmogorov-Smirnov Test) and the homogeneity of variance

(Levene Test), by analysis of variance for repeated measurements, followed by



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Results

Participants 13 A cohort study was carried out, between July 2012 and January 2013, at the Instituto de

Medicina Integral Prof. Fernando Figueira (IMIP), in Recife, Brazil, with 64 hospitalized

newborns, from which 38 preterm in the Kangaroo Unit sector and 26 term in the Nursery

sector of the IMIP hospital.

Three groups were designed: Group 1 (n=25): preterm newborns in kangaroo position (PT –

KAN); 2) Group 2 (n=13): preterm newborns not in kangaroo position (PT – NKAN); and 3)

Group 3 (n=16): term newborns (T).

Descriptive data 14 The clinical and biological characteristics of the newborns in each group can be seen in

Table 1.

The newborns were kept in the kangaroo position for 8-12 hours per day, until the evaluation

after 48h.

Outcome data 15 In the PT – KAN group, electromyographic activity was first recorded before neonate being

in kangaroo position (0h). Immediately after taking this record, the neonates were placed for

the first time in the kangaroo position. The kangaroo position adopted was that

recommended by the Kangaroo Unit, in which the newborn is positioned against the adult’s

chest, face down, wrapped in a strip of flexible cloth. Subsequent recordings were taken

immediately after 48h of the kangaroo position and, finally, at term-equivalent age (40 ± 1

weeks). The newborns were kept in the kangaroo position for 8-12 hours per day, until the


In the PT – NKAN group the measurements were made at 0h and 48h. In the T group

electromyographic activity was measured only once, at a chronological age until 24h.

Main results and

Other analyses

16 Variances analyses comparison of the RMS among measurements (Table 2) demonstrated a

significant difference (F(5,108)= 56.69; p<0.001). The post hoc multiple comparisons (Holm-

Sidak Method) showed that in the PT-KAN Group the RMS was greater at 48h (p=0.004)

and at age equivalent to term (p=0.004) compared with the measurement at 0h, but there is

no statistically significant difference between the measurements at 48h and at age equivalent

to term. In the PT-NKAN group no significant difference was found between 0h and 48h.

The RMS in the PT-KAN group at age equivalent to term was greater than in the T Group

(p=0.004).

Discussion

Key results 17 The results were discussed based on current references.

Limitations 18 One limitation of the present study is the absence of a group of preterm newborns not in

kangaroo care followed up to age equivalent to term, as this would shed light on whether the

increase in electromyographic activity in the preterm newborns at age equivalent to term is

only related to the growth and development of the neonates and not the influence of the

kangaroo position. However, the reduced myoelectrical response in group T suggests that it

is the kangaroo position and not the growth of the newborns per se that is responsible for the

changes in electromyographic activity observed here. Apart from this limitation, the sample

size was lower than the estimate so it is a factor that may diminish the reliability of our

findings. However with a sample power of 90%, the large differences found between the

means and the statistically significant figures may support our inferences.

Interpretation 19 An overall cautious interpretation of the results was performed, considering objectives,

limitations, multiplicity of analyzes, results from similar studies, and other relevant evidence.

Generalisability 20 The generalization (external validity) of study results was discussed

Other information

Funding 21 The source of funding and the role of the funders for the study is described in the article.

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bmj open · date submitted by the author: 25-apr-2014 complete list of authors: miranda, rafael;...

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