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1985; 65:1363-1364.PHYS THER.McCrannDonna L Keenan, Linda Simonsen and Donald JControl During Labor and Delivery: A Case ReportTranscutaneous Electrical Nerve Stimulation for Pain

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1985; 65:1363-1364.PHYS THER.McCrannDonna L Keenan, Linda Simonsen and Donald JControl During Labor and Delivery: A Case ReportTranscutaneous Electrical Nerve Stimulation for Pain

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Trans cu taneou s E lec t r ica l Ne rve S tim ulat ionfo r Pain Co n t ro l Dur ing Labor an d De liveryA C a s e R e p o r tD O N N A L . K E E N A NL I N D A S I M O N S E N

a n d D O N A L D J . M c C R A N N

K ey Wo r d s : Electric stimulation Labor Pain.

Transcutaneous electrical nerve stimulation (TENS) hasbeen used to diminish postoperative pain 1 and many formsof chronic pain 2 with reportedly good results. There h ve beenfew reports of the use of TENS during childbirth in thephysical therapy literature. Several European studies havereported good effects of TENS in the reduction of painassociated with labor and delivery. 3-6 Because TENS is anoninvasive analgesic procedure and no maternal or fetal sideeffects have been encountered,3-5 a firsthand evaluation ofthis modality seemed appropriate. In this case study, weportray how TENS was used with one patient to promptphysical therapists and other health care providers to developprotocols and conduct research for use of this modality.

Melzack and Wall's gate control theory of pain providesone theoretical foundation for TENS. 7 According to thishypothesis, electrical stimulation of the large, afferent, highvelocity fibers prevents the smaller, slow velocity, pain-carrying A delta and C fibers from transmitting pain signals tothe higher brain centers. In keeping with Melzack's theory,

high frequency, low intensity TENS blocks the transmissionof nociceptive stimuli to the spinal cord.8

Labor and delivery are divided into three stages. Stage onebegins with contractions of the uterus that efface and dilatethe cervix and that cause pain receptors to be activated. 9,10

The evoked impulses are transmitted by the afferent fibersthrough the uterine, pelvic, and hypogastric plexes and reachthe spinal cord through dorsal roots at T10-L1. Once thecervix is fully dilated (10 cm), the second stage of l bor begins;the contractions of the uterus and voluntary contractions ofthe abdominal muscles push the baby through the vaginalcanal. Pain receptors are activated by dilation of the vagina,pelvic floor, vulva, and perineum. The evoked impulses are

transmitted by afferent fibers through the pudendal nervesand reach the spinal cord through dorsal roots S2-4.9, 10 Thethird st ge of l bor is the delivery of the b by and the placenta.

M AT E R I A L S A N D M E T H O D S

A Neuromod Selectra* TENS unit with dual channel output was used. As photographed by Robson, 4 two EPC and

two Stemmen disposable electrodes were applied on theparaspinal muscles from T10-L1 and at S2 and S3, respectively. The thoracic-lumbar electrodes were controlled bychannel I, and channel II controlled the sacral electrodes.During the trial, the unit was kept in a high frequencycontinuous mode and a spike wave form was used.

P a t i en t D a t a

The patient was a 29-year-old woman; this was her firstpregnancy and the gestation period was 4 2 weeks. The pregnancy had been uncomplicated except for the prolongedgestation, m ild pregnancy-induced hypertension w ith edema,proteinuria, and a 16-kg (35 lb) weight gain. Her preparationfor l bor and delivery included ttending a prep red childbirthclass with instruction in Lamaze breathing and relaxationtechniques and practice with the Neuromod Selectra TENSunit. Before childbirth, she also received instruction from oneof us (D.L.K.) in the use of the Neuromod Selectra TENS

unit in conjunction with Lamaze breathing and relaxation.

T R E AT M E N T A N D R E S U LT S

The patient had spontaneous rupture o f the amniotic membranes four hours before admission to the hospital withoutspontaneous contractions. Labor was induced by intravenousoxytocin drip, and continuous external fetal m onitoring wasinitiated through transabdominal ultrasound with a transabdominal tocodynamometer to record uterine contractions.No other medication, except for local anesthetic for an episi-otomy, was administered during labor and delivery.

The TENS unit was started after 2.5 hours of labor whencontractions were two minutes apart and uncomfortable forthe patient. The pulses per second were set at 85, and theintensity on channel I was adjusted to produce a comfortable

buzzing sensation (Table). During uterine contrac tions, theintensity was increased to a level where a strong musclecontraction was achieved under the thoracic electrodes. Eachuterine contraction could be felt by the patient as a strongpulling sensation in the lower abdominal area. The musclecontraction provided by the TENS unit was described as adeep pressure or m ss ge th t helped diminish the discomfort.The perceived strength of the uterine contraction was greaters. Keen an was Staff Physical Therapist, Main e Medical Center, Portland,

ME 04102, when this paper was written. Address all correspondence to 597Sawyer St, S Portland, ME 0410 6 (U SA).

Ms. Simonsen is Senior Physical Therapist, Maine Medical Center.Dr. McCrann is Acting Director of Perinatology, Department of Obstetrics-

Gynecology, Maine Medical Center.This article was submitted February 17, 1984; was with the authors forrevision 35 weeks; and was accepted March 21, 1985.

Model 772 0, Medtronic Inc, 3055 Old Highway Eight, Minneapolis, M N

55440. Codman and Shurtleff Inc, Pacella Park Dr, Randolph, MA 0236 8. Stemmen Laboratory, Inc, 1850 Whittier Ave, Costa Mesa, CA 92627.

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when the TENS unit was turned off and the patient electedto continue using the TENS unit.

Channel II and the sacral electrodes were also tried. Thesmaller area of the Stemmen electrode, however, produced asharp, stinging sensation. Because this was uncomfortable forthe patient, the use of this channel was discontinued. TheEPC electrodes were not applied to the sacral area becausethe patient was able to maintain a comfortable, relaxed stateduring each contraction by using only channel I.

The T ENS unit w as used during two hours of active labor:the early transition phase (2-8-cm dilation) while the p atientsa t in a rocking chair and the late transition phase (8-10-cmdilation) while the patient was in a side-lying position in b ed.Pain was kept at a tolerable level during both stages by theTENS-produced muscle contraction, total body relaxation,and breathing techniques. During the early transition stage,the p atient herself could easily adjust the intensity of the u nitaccording to the strength of the uterine contraction. Theintensity was decreased to the lowest comfortable level be-tween contractions to minimize accom modation to the stimulation (Table). During the late transition stage, when uterinecontractions became very strong and close together, increased

patient concentration was required and she no longer couldcontrol the TENS intensity herself. Instead, the therapistadjusted the intensity by observing the behavior of the patientand uterine contractions recorded on the fetal m onitor.

As labor progressed to the second stage (full dilation of thecervix), the uterine contractions became farther apart and lessintense. During this stage, the patient had to push effectivelywith the abdominal m uscles and therefore, needed to concentrate on and experience the full strength of the uterine contraction. The muscle contraction produced by the TENS unitwas too distracting to allow this concentration; therefore, theTENS unit was discontinu ed after 2.5 hours. Contrary tosome reports that the TENS unit disrupted the fetal ECG

signal from internal fetal monitors,5 the TENS unit did not

produce any artifact in the fetal heart-rate tracing producedby ultrasound with the external monitor.

D IS CU S S IO N

In this trial, only one ch annel of the unit w as used. Becauseof the strength of the uterine contractions and accommodation to the stimu lation, the patient was using the full o utputof channel I at the e nd of the transition phase. A second setof EP electrodes instead of the smaller Stemmen electrodesapplied to the sacral area may be helpful to increase thecomfortable sensation from the TENS stimulation. In thistrial, TENS was discontinued during the second stage of labor.If discomfort was experienced between contractions duringthis stage, a low level of stimulation could be maintained.This low level would not mask the strength of the uterinecontractions and would allow the patient to push effectivelywith the abdominal muscles.

For TENS to be used successfully during childbirth, thepatient must understand the use of the unit before beginninglabor. Theory of pain control and application of the unitcould be taught as par t of a prepared childbirth class. Unde rthe supervision of class instructors, patients could simulateconditions during childbirth by practicing total body relaxation and breathing techniques in com bination with low intensity stimulation through electrodes placed on an extremity toavoid stimulation near the baby without fetal monitoring.

TABLETranscutaneous Electrical Nerve Stimulation Pulse Rate and

Intensity of Channel 1

Stimulation Factors

Pulse rate (pps)Intensity between uterine

contractions ( output)Intensity during uterine

contractions ( output)

Time Since Application of

TENS Unit* (hr)

0

85

25

38

0 5

85

35

55

1

85

65

80

1 5

85

80

99

2

99

70

85

2 5

99

85

99

The TENS could then be started in early labor and theintensity controlled by the patient through the active phaseof stage one. In our case study, a health professional had tocontrol the intensity during the transition phase (8-10 cm).A physical therapist or a labor room nurse who has beeneducated in the use of this modality can provide this serviceor supervise the patient s labor coach, who can control theunit if necessary. Physical therapists may also wish to instru ctpatients in TE NS use in childbirth education classes.

According to the literature , the effectiveness of TENS forpain control in labor is equivocal.3-6 The patient in this casereport, however, was more comfortable using TENS thanwhen the unit was turned off. Lamaze breathing and relaxation is an accepted practice during most labor and delivery.Therefore, we chose to evaluate the effectiveness of TENS inaddition to these pain reduction measures. The use of asubjective rating scale during labor and delivery would behelpful to evaluate pain control in future studies. The favorable results of this case study and the benign nature of thismodality suggest that TENS could effectively complement

other methods of pain control for childbirth. Controlled studies with large numbers of patients, however, are needed toevaluate possible long-term fetal effects and to develop protocols for the use of TE NS during labor and delivery. Obstetrical physicians will delay general acceptance of this m odalityuntil appropriate studies have proved its efficacy and safety.

Acknowledgment The authors wish to thank M ary Hutchinson, RN, for her assistance in this case study.

REFERENCES

1 . Smith MJ: Electrical stimulation for relief of musculoskeletal pain. ThePhysician and Sportsmedicine 1 1 5):47-55,19 83

2 . Melzack R:

Prolonged relief of

pain by

brief, intense, transcutaneoussomatic stimulation. Pain 1: 357-373,1 9753. Augustinsson LE, Bohlen P Bundsen P et al: Pain relief during delivery

by transcutaneous electrical nerve stimulation. Pain 4:59-65,19774. Robson JE: Transcutaneous nerve stimulation for pain relief in labour.

Anesthesia 34:357-361,19795. Bundsen P, Peterson L E, Selstam U: Pain relief in labor by transcutaneous

electrical nerve stimulation: A prospective matched study. A cta ObstetGynecol Scand 60:459-468,1981

6. Neshein Bl: The use of transcutaneous nerve stimulation for pain reliefduring labor: controlled clinical study. cta Obstet Gynecol Scand 6 0 : 1 3 -1 6 , 1 9 8 1

7. Melzack R Wall PD: Pain mechanism: A new theory. Science 1 5 0 : 9 7 1 -973,1965

8. Stratton SA: Role of endorphins in pain modulation. The Journal of Or-thopedic and Sports Physical Therapy 3:20 0-205,1 982

9. Bonica JJ : Principles and Practice of Obstetric Analgesia and Anesthesia:Fundamental Considerations. Philadelphia, PA, F A Davis Co, 1 967, vol 1

1 0. Bonica J J: The nature of pain in parturition. Clin Obstet Gynecol 2:499-516 ,1975

* The TENS unit was applied 2.5 hours after induction of labor.

1364 PHYSICAL THERAPY