DEPARTMENT OF PAEDIATRICS DEPARTMENT OF PAEDIATRICS WITH MEDICAL GENETICSWITH MEDICAL GENETICS

THEME OF LECTURETHEME OF LECTURE

“ “ Respiratory disorders Respiratory disorders syndrome”syndrome”

Determination and actualityRespiratory disorders syndrome (Respiratory disorders syndrome (RDSRDS) - unspecific ) - unspecific symptom symptom

complexcomplex of many diseases of newborn, which shows development of of many diseases of newborn, which shows development of respiratory insufficiency (RI) and arises up in the first minutes, hours or days respiratory insufficiency (RI) and arises up in the first minutes, hours or days

of life. of life.

RDSRDS of the I type (respiratory distress-syndrome ) - diseases of of the I type (respiratory distress-syndrome ) - diseases of newborns from newborns from GGP o <32-34 P o <32-34 weeksweeks., principal reason and chain of pathogeny ., principal reason and chain of pathogeny

is a primary lack of the system of is a primary lack of the system of surfactantsurfactant. To this type belong . To this type belong pneumopathy (disease of pneumopathy (disease of hyalinehyaline membranes, membranes, atelectasisatelectasises, es,

edematously-edematously-hahaemorrhagicemorrhagic syndrome. syndrome.

RDSRDS of the II type - disease, the secondary violation of the of the II type - disease, the secondary violation of the surfactantsurfactant system which results in the reduced synthesis. To this type belongs of system which results in the reduced synthesis. To this type belongs of

meconium aspiratonmeconium aspiraton syndrome(MAS), defect of development of lungs and syndrome(MAS), defect of development of lungs and heart, birth trauma.heart, birth trauma.

In the structure of early In the structure of early neonatal neonatal death in Ukraine death in Ukraine RDSRDS occupies a occupies a leading place and is 16%. RDS develops in 20% leading place and is 16%. RDS develops in 20% premature premature newborns, and newborns, and

for children which borned before 28 weeks of for children which borned before 28 weeks of gestationgestation this pathology reaches this pathology reaches 80%. The general death rate of children from 80%. The general death rate of children from RDS RDS reaches 25%.reaches 25%.

Surfactant and its functionsSurfactant is a monomolecular layer on the surface of section Surfactant is a monomolecular layer on the surface of section

between the epithelium of alveoli and air, it is between the epithelium of alveoli and air, it is lipoproteinlipoprotein (90% (90% lipidlipids and 10% albumenss and 10% albumens-apoprotein-apoproteins), that is s), that is synthesized by alveolocytes of II order from 25-26 weeks synthesized by alveolocytes of II order from 25-26 weeks of of gestationgestation ( surfactant of the I type), more active ( surfactant of the I type), more active synthesis takes a place from 34 weeks of synthesis takes a place from 34 weeks of gestationgestation ( surfactant of II type). ( surfactant of II type).

Functions of Functions of surfactantsurfactant::-- hinders the slump of alveoli while on breath;hinders the slump of alveoli while on breath;-- protects lungs from epithelium damages and promote protects lungs from epithelium damages and promote

mucociliary clearance;mucociliary clearance;-- has bactericidal activity, stimulates macrophage reaction has bactericidal activity, stimulates macrophage reaction

in lungs;in lungs;-- takes part in adjusting of microcirculation in lungs and takes part in adjusting of microcirculation in lungs and

penetrabilitypenetrability of walls of alveoli. of walls of alveoli.

Basic factors of RDS are in newborn PulmonaryPulmonary::

-- pneumopathypneumopathy ((respiratory distress-syndrome); ((respiratory distress-syndrome);-- transient transient tachytachypnpnea of newborn (ea of newborn (TTNTTN););-- pneumonia;pneumonia;-- meconium aspiraton meconium aspiraton syndrome (MAS);syndrome (MAS);-- pulmonary bleeding;pulmonary bleeding;-- diaphragmatic herniadiaphragmatic hernia;;-- inheritated defects of development of lungs and thorax.inheritated defects of development of lungs and thorax.

Extrapulmonary:Extrapulmonary:-- inherited defects of heart and vessel;inherited defects of heart and vessel;-- persistent fetalpersistent fetal circulation; circulation;-- patent ductus arteriosus;patent ductus arteriosus;-- perinatalperinatal defeat of CNS, birth trauma. defeat of CNS, birth trauma.

Factors which cause development of RDS

-- diabetes mellitus at a mother ;diabetes mellitus at a mother ;

-- births by a way of cesarean delivery;births by a way of cesarean delivery;

-- male child;male child;

-- being born the second of twins;being born the second of twins;

-- isoserologicisoserologic incompatibility of blood of mother and incompatibility of blood of mother and fetusfetus;;

-- IUI;IUI;

-- morphofunctional immaturity of newborn;morphofunctional immaturity of newborn;

-- inherited endocrine and congenital pathology;inherited endocrine and congenital pathology;

-- metabolic disorders (metabolic disorders (hypovolemiahypovolemia, anaemia, , anaemia, polycytemia, hypoglycemia, hypothermia, acidosis ).polycytemia, hypoglycemia, hypothermia, acidosis ).

Main links of pathogeny RDS of the Ist type collapse of alveoli on breath;collapse of alveoli on breath;

-- hypoxiahypoxia, acidosis, hypercapnia;, acidosis, hypercapnia;

-- spasm of pulmonary artery;spasm of pulmonary artery;

-- shunting of blood;shunting of blood;

-- DIC-syndrome;DIC-syndrome;

-- haemorrhageshaemorrhages;;

-- activating of Lactivating of LP P (lipid peroxidation);(lipid peroxidation);

-- cardiac insufficiency;cardiac insufficiency;

-- hypovolemiahypovolemia;;

-- suppression of immunity.suppression of immunity.

Pathogeny of Pathogeny of RDSRDS of the I type is always includes of the I type is always includes: : atelectasisatelectasis ( the plasma ( the plasma impregnatimpregnation ion of a vascular wall), of a vascular wall), edematously-haemorrhagicedematously-haemorrhagic syndrome syndrome ( the plasma ( the plasma impregnatimpregnation of ion of a vascular wall and alveoli results in edema; the plasma and a vascular wall and alveoli results in edema; the plasma and blood corpuscleblood corpuscles s impregnatimpregnation of a vascular wall and alveoli results in ion of a vascular wall and alveoli results in haemorrhageshaemorrhages), formation of ), formation of hyalinehyaline membranes membranes (DHM). (DHM).

Main in pathogeny of Main in pathogeny of RDSRDS of the II type of the II type there is the secondary violation of the there is the secondary violation of the surfactantsurfactant system with the promoted level of degradation of phospholipides as a result system with the promoted level of degradation of phospholipides as a result of concomitant factors (of concomitant factors (hypoxiahypoxia, metabolic disorders, infections), that results in , metabolic disorders, infections), that results in violation of violation of ventilation-perfusionventilation-perfusion relations in lungs with development of RI . relations in lungs with development of RI .

Classification By type of By type of RDSRDS: : RDS RDS of the I-st type and of the I-st type and RDS RDS of the II-nd type of the II-nd type By type of By type of pneumopathypneumopathy for for RDSRDS of the I-st type: DHM, of the I-st type: DHM, atelectasisatelectasis, ,

edematously-haemorrhagicedematously-haemorrhagic syndrome. syndrome. By leading factor for By leading factor for RDS RDS of the II-nd typeof the II-nd type: : perinatalperinatal defeat of CNS, birth defeat of CNS, birth

trauma, morphofunctional immaturity, metabolic violations, defects of trauma, morphofunctional immaturity, metabolic violations, defects of development of heart and lungs.development of heart and lungs.

Severity of respiratory disordersSeverity of respiratory disorders: severe (estimation is according to the scales of : severe (estimation is according to the scales of Douness or Silverman is > 7 points), moderate (estimation according to the Douness or Silverman is > 7 points), moderate (estimation according to the scales of Douness or Silverman is 4-6 points), mild (estimation according to scales of Douness or Silverman is 4-6 points), mild (estimation according to the scales of Douness or Silverman is 1-3 points). the scales of Douness or Silverman is 1-3 points).

By degree of RIBy degree of RI: I -: I - ІІІ ІІІ degreedegree By complication:By complication: pneumonia, sepsis, pulmonary pneumonia, sepsis, pulmonary dysplasiadysplasia, pneumothorax ., pneumothorax . Example of diagnosis:Example of diagnosis: RDS RDS of the I-st type, disease of of the I-st type, disease of hyalinehyaline membranes, membranes,

severe respiratory disorders ( estimation is according to the scales of Silverman severe respiratory disorders ( estimation is according to the scales of Silverman is 7 points), RI of II degree, without complications. is 7 points), RI of II degree, without complications. PrematurityPrematurity of II degree. of II degree. Birth trauma of CNS, PVH of I degree, acute period, moderate degree. Birth trauma of CNS, PVH of I degree, acute period, moderate degree. RDS RDS of of IInd type, moderate respiratory disorders (estimation is according to the scales IInd type, moderate respiratory disorders (estimation is according to the scales of Douness is 4 points), RI of III degree, without complications.of Douness is 4 points), RI of III degree, without complications.

ClinicIt shows up by the symptoms of RI: shortness of breath, It shows up by the symptoms of RI: shortness of breath,

tachypneatachypnea, blowing of wings of nose, , blowing of wings of nose, intercostal retractionintercostal retraction, , participating in the act of breathing of auxiliary musculature, participating in the act of breathing of auxiliary musculature, cyanosiscyanosis, expiration noises., expiration noises.

RIRI is the state of organism, at which support of the normal gas state is the state of organism, at which support of the normal gas state of blood,is not provide which results in the decline of functional of blood,is not provide which results in the decline of functional possibilities of organism. possibilities of organism.

At At RI RI of I-st degree - the defeat of lungs is clinically compensated of I-st degree - the defeat of lungs is clinically compensated by hyperventilation. A shortness of breath is only at physical by hyperventilation. A shortness of breath is only at physical activity. Hemodynamic disorders are absent. activity. Hemodynamic disorders are absent.

At At RIRI of IInd degree - the clinical and laboratory signs of violation of IInd degree - the clinical and laboratory signs of violation of the external breathing and hemodynamic are subcompensated. of the external breathing and hemodynamic are subcompensated. Shortness of breath and Shortness of breath and cyanosiscyanosis is in the motionless state. is in the motionless state.

At At RIRI of IIIrd degree is clinical and laboratory decompensation of of IIIrd degree is clinical and laboratory decompensation of the external breathing and the external breathing and hemodynamichemodynamic. Shortness of breath in a . Shortness of breath in a state of rest and against the background of oxygen therapy.state of rest and against the background of oxygen therapy.

DiagnosticsPerinatalPerinatal is based on the results of estimation of maturity of the is based on the results of estimation of maturity of the

surfactantsurfactant system of system of fetusfetus. In . In amniotic fluidamniotic fluid the level of the level of saturation of saturation of lecithinlecithin, determined and also correlation of levels , determined and also correlation of levels of of lecithinlecithin and and sphingomyelinsphingomyelin. If level of saturation of . If level of saturation of lecithinlecithin is >5 mg/l, a risk of development of is >5 mg/l, a risk of development of RDSRDS is <1%. If correlation is <1%. If correlation of of lecithin lecithin andand sphingomyelin sphingomyelin is >2, the probability of is >2, the probability of development of development of RDSRDS is 2%; if correlation of is 2%; if correlation of lecithin lecithin andand sphingomyelin sphingomyelin is 1or 2, the probability of development of is 1or 2, the probability of development of RDSRDS is 50%; if correlation of is 50%; if correlation of lecithin lecithin andand sphingomyelin sphingomyelin is <1, the is <1, the probability of development of probability of development of RDSRDS is 75%. is 75%.

The risk of development and degree of severity of The risk of development and degree of severity of RDSRDS in newborns in newborns is determined by the scale of Silverman-Andersen. The is determined by the scale of Silverman-Andersen. The respiratory function of fullterm infant which has a threat of respiratory function of fullterm infant which has a threat of development of development of RDSRDS, during the first days should be evaluated , during the first days should be evaluated according to the scale of Downess. Point 4 or more proves according to the scale of Downess. Point 4 or more proves RIRI and demands monitoring of gas composition of blood. Point 7 and demands monitoring of gas composition of blood. Point 7 demands demands artificial pulmonary ventilationartificial pulmonary ventilation(APV).(APV).

DiagnosticsLaboratory and auxiliary methods of researchLaboratory and auxiliary methods of research::

- - clinical blood analysis is obligatory clinical blood analysis is obligatory determination of determination of hematocrithematocrit and and thrombocytesthrombocytes;;

- glucose blood analysis ;- glucose blood analysis ;- determination of arterial blood gas composition;- determination of arterial blood gas composition;- ABB( asid base balance);- ABB( asid base balance);- roentgenologic chest examination;- roentgenologic chest examination;- echocardiography;- echocardiography;- neurosonography;- neurosonography;- hyperoxic and hyperventilation tests.- hyperoxic and hyperventilation tests.

Differential diagnostic criteria of disease of hyaline membranes (DHM)

It in develops 95% of cases in It in develops 95% of cases in premature bornpremature born. . Characteristic presence of lucid space, but not Characteristic presence of lucid space, but not more than for 6 hours. The shortness of breath and more than for 6 hours. The shortness of breath and expiration noises prevails in a clinic (“grunting” expiration noises prevails in a clinic (“grunting” expirationexpiration). Roentgenologic chest examination ). Roentgenologic chest examination shous diffuse focuses of the reduced transparency - shous diffuse focuses of the reduced transparency - “clouded glass”, “graininess” of pulmonary “clouded glass”, “graininess” of pulmonary picture, aerial picture, aerial bronchogrambronchogram. Arterial . Arterial hypoxemiahypoxemia and and hypercapniahypercapnia, metabolic mixed acidosis , metabolic mixed acidosis

Differential diagnostic criteria to atelectasis of lungs

It is often combined with the It is often combined with the hypoxichypoxic defeat of defeat of CNSCNS, , birth trauma, general immaturity. It develops from birth trauma, general immaturity. It develops from the first minutes of life, characteristic shortness of the first minutes of life, characteristic shortness of breath of inspiratory character. Cyanosis is breath of inspiratory character. Cyanosis is prevailing in a clinical presentation. At prevailing in a clinical presentation. At percussion percussion local reduction of percussion sound is observed.local reduction of percussion sound is observed.

Roentgenologic chest examination shous decline of Roentgenologic chest examination shous decline of transparency and pneumatization of pulmonary transparency and pneumatization of pulmonary tissue.tissue.

Differential diagnostic criteria of edematously-haemorrhagic syndrome

Often at Often at prematureprematurely born fetus and children from ly born fetus and children from mothers with cardio-vascular pathology. mothers with cardio-vascular pathology. Respiratory insufficiency develops sometime after Respiratory insufficiency develops sometime after birth. Clinical presentation: bloody discharges birth. Clinical presentation: bloody discharges from a mouth, general from a mouth, general edematousedematous syndrome, syndrome, hemorrhages in a skin, internal organs, increase of hemorrhages in a skin, internal organs, increase of liver. At auscultation - numerous rales are against liver. At auscultation - numerous rales are against the background of the weakened breathing. the background of the weakened breathing. Roentgenologic chest examination shous: Roentgenologic chest examination shous: “blurred” X-ray picture with the “butterfly-like” “blurred” X-ray picture with the “butterfly-like” shadowing in core areasshadowing in core areas

Differential diagnostic criteria of meconium aspiraton syndrome (MAS).

Often at Often at pospostmature children and children with IGR tmature children and children with IGR (intrauterine growth retardation). Amniotic fluid (intrauterine growth retardation). Amniotic fluid is dirty, there is presence of is dirty, there is presence of meconiummeconium in in oropharynx, stomach, tracheobronchial system and oropharynx, stomach, tracheobronchial system and on a child’s skin. From the first minutes of life on a child’s skin. From the first minutes of life there is shortness of breath of mixed character, there is shortness of breath of mixed character, discharge of discharge of amniotic fluidamniotic fluid from the mouth and from the mouth and nose. At auscultation - numerous rales of different nose. At auscultation - numerous rales of different calibres . Roentgenologic chest examination calibres . Roentgenologic chest examination shous: shous: excessive excessive expansion of lungs and flattering expansion of lungs and flattering of diaphragma.of diaphragma.

Treatment1.Providing of adequate treatment and protective r1.Providing of adequate treatment and protective regimenegimen..

Limitation of injuring factors.Limitation of injuring factors.2.2.InfusionInfusion therapy therapy. It is carried out for 40-60 min. after birth, . It is carried out for 40-60 min. after birth, the volume on the 1st day is 50-60 ml/kg, in future for 20 the volume on the 1st day is 50-60 ml/kg, in future for 20 ml/kg is added every day. It is obligatory to account ml/kg is added every day. It is obligatory to account diuresis diuresis every hour and to estimatethe water balance ( the volume of every hour and to estimatethe water balance ( the volume of infused and excreted out liquid, the volume and specific infused and excreted out liquid, the volume and specific density of urine), and also the control of electrolyte density of urine), and also the control of electrolyte composition of blood. The advantage is given to 10% solution composition of blood. The advantage is given to 10% solution of glucose.of glucose.3.Providing of adequate 3.Providing of adequate feedingfeeding - - paranteralparanteral ( the first 3 days of ( the first 3 days of life), during stabilizing of the condition (heart rate (HR) life), during stabilizing of the condition (heart rate (HR) <60/min, if there is no <60/min, if there is no apnoeapnoea and regurgitations) - a and regurgitations) - enteralenteral..4.The 4.The antibacterial therapyantibacterial therapy is indicated for all of children is indicated for all of children (cefuraximi + (cefuraximi + gentamycingentamycin). ).

Treatment5. 5. Respiratory therapyRespiratory therapy::

The release upper respiratory tracts. The intubation of trachea The release upper respiratory tracts. The intubation of trachea and sanation of tracheobronchial system is indicated for all and sanation of tracheobronchial system is indicated for all children with MAS not active at birth (we should assess the children with MAS not active at birth (we should assess the HR, breathing and muscle tone);HR, breathing and muscle tone);Oxygen therapy (through a crater, oxygen tent, nasal tubes, Oxygen therapy (through a crater, oxygen tent, nasal tubes, oxygen therapy in cuvees;oxygen therapy in cuvees;Spontaneous breathing under permanent positive pressure Spontaneous breathing under permanent positive pressure (SBUPPP) - improves oxygenation through the increase of (SBUPPP) - improves oxygenation through the increase of functional remaining volume of lungs, straightens alveoli, functional remaining volume of lungs, straightens alveoli, restores in a ventilation-perfusion relations. The indications for restores in a ventilation-perfusion relations. The indications for SBUPPP: growth of SBUPPP: growth of RI RI symptoms on a background of the use symptoms on a background of the use of oxygenotheraphy the help of simple methods, estimation of oxygenotheraphy the help of simple methods, estimation according Silverman or Dovness scale > 4 points, negative according Silverman or Dovness scale > 4 points, negative “foamy” test, “foamy” test, apnoeapnoea of a of premature bornpremature born, bradycardia, child , bradycardia, child “removal” of ALV. Initial parameters of SBUPPP: expiratory “removal” of ALV. Initial parameters of SBUPPP: expiratory airway pressure is 5 cm of water column., concentration of airway pressure is 5 cm of water column., concentration of oxygen is 60%.oxygen is 60%.

Treatment

AArtificial pulmonary ventilationrtificial pulmonary ventilation(APV).(APV). Indications: estimation according Silverman and Indications: estimation according Silverman and

Downess scale is > 7 points; the use of SBUPPP Downess scale is > 7 points; the use of SBUPPP is insufficient if Pa is insufficient if Pa О2<50О2<50 mm of mercury mm of mercury column , Pa column , Pa СО2>60СО2>60 mm of mercury column mm of mercury column, , Ph Ph <7,2; shock; the protracted attacks of <7,2; shock; the protracted attacks of apnoe apnoe wich wich bradycardiabradycardia and and cyanosiscyanosis; persistant central ; persistant central cyanosiscyanosis on the background of on the background of SBUPPPSBUPPP; arterial ; arterial hypotensiahypotensia; violation of peripheral ; violation of peripheral hemodynamichemodynamic..Inhalation therapy (Inhalation therapy (lazolvanlazolvani, i, aminophyllineaminophylline, , hydrocortisone, vitamin C, 2% solution of sodium hydrocortisone, vitamin C, 2% solution of sodium or kalium chloridy), an ultrasonic inhaler is used.or kalium chloridy), an ultrasonic inhaler is used.

Treatment6.The use of exogenous 6.The use of exogenous surfactantsurfactant. 3 types are distinguished:. 3 types are distinguished:-- natural animal - “Curosurf”, “Sukrime”;natural animal - “Curosurf”, “Sukrime”;-- synthetic - “Eksosurf”;synthetic - “Eksosurf”;-- natural human “ Surfactant of natural human “ Surfactant of HLHL”.”.Natural animal preparations are preferred. Natural animal preparations are preferred. Indications for injection of Indications for injection of surfactant surfactant preparationspreparations::-prophylactic injection. For prematurely born with -prophylactic injection. For prematurely born with GPGP <30 <30 weeks weeks

and with body mass at birth <1250g, . for children with body mass and with body mass at birth <1250g, . for children with body mass >1250g, in case of confirmation of lungs immaturity with the help >1250g, in case of confirmation of lungs immaturity with the help of objective methods during the first 15-30 min. of life. of objective methods during the first 15-30 min. of life.

-medical injection. It does not depend on GA, it is based on the -medical injection. It does not depend on GA, it is based on the following criteria: the diagnosis following criteria: the diagnosis RDSRDS is confirmed clinically and is confirmed clinically and roentgenologically, Pa roentgenologically, Pa О2<80О2<80 mm of mercury column, if we use mm of mercury column, if we use 30% of oxygen;30% of oxygen;

The The surfactant surfactant injected during the first 2 hours after birth. The injected during the first 2 hours after birth. The repeated injected is carried out in 6 hours, if a child needs repeated injected is carried out in 6 hours, if a child needs AVLAVL or or if we use 30% of oxygen, Pa if we use 30% of oxygen, Pa О2О2 <80 mm of mercury column <80 mm of mercury column

Treatment

Contraindications for introduction of Contraindications for introduction of preparations of preparations of surfactantsurfactant::

-- defects of development, incompatible with life;defects of development, incompatible with life;-- atresia of gullet;atresia of gullet;-- pulmonary bleeding;pulmonary bleeding;-- considerable violations of vital functions and considerable violations of vital functions and

metabolism (hypothermia of <35C, metabolism (hypothermia of <35C, bradbradycycardiaardia, arterial , arterial hypertensiahypertensia, metabolic , metabolic acidosis );acidosis );

-- severe organic defeats of severe organic defeats of CNSCNS..

Treatment

7. Diuretic therapy ( lazycs of 1-4 mg/kg/day, 7. Diuretic therapy ( lazycs of 1-4 mg/kg/day, aminophyllineaminophylline 0,1 ml/kg) - will liquidate the edema of 0,1 ml/kg) - will liquidate the edema of cerebrum, stimulates a respiratory center, improves cerebrum, stimulates a respiratory center, improves blood circulation through lungs, liver.blood circulation through lungs, liver.

8. Corticosteroid therapy ( dexamethasone 1 mg/kg, 8. Corticosteroid therapy ( dexamethasone 1 mg/kg, during 3-5 days) - stabilizes hemodynamic and during 3-5 days) - stabilizes hemodynamic and stimulates the stimulates the surfactant surfactant production.production.

9. Heparinotheraphy - with the purpose of prophylaxis of 9. Heparinotheraphy - with the purpose of prophylaxis of DIC-syndrome. 1-2 day 100 UA( unit of activity) 4 DIC-syndrome. 1-2 day 100 UA( unit of activity) 4 times /day , 3-4th day 75 UA 3 times/day, 6-7th day 25 times /day , 3-4th day 75 UA 3 times/day, 6-7th day 25 UA /day.UA /day.

Complication of intensive therapy for children from RDS

Complications of incorrect oxygnotheraphy – Complications of incorrect oxygnotheraphy – bronchopulmonary displasia and bronchopulmonary displasia and retinopathyretinopathy of of

premature bornpremature born. . Development and progress of Development and progress of PVPVH, which is the H, which is the

principal reason of children death from principal reason of children death from RDSRDS..Violation of Violation of hemodynamichemodynamic is the functioning arterial is the functioning arterial

duct and transition pulmonary duct and transition pulmonary hypertensiahypertensia..

To avoid above mentioned complications we should To avoid above mentioned complications we should accursedly follow the principles of treatmentaccursedly follow the principles of treatment

Preventive measures

To prevent RDS we should take preventive To prevent RDS we should take preventive measures of preterm delivery.measures of preterm delivery.

Antenatal a Antenatal a steroisteroid prophylaxis is carried out d prophylaxis is carried out among pregnancy women of 23-34 among pregnancy women of 23-34 weeks weeks who have a risk of preterm delivery. who have a risk of preterm delivery. Dexamethasone is used- 6 Dexamethasone is used- 6 mg mg with interval6 with interval6 hours 4 introductions intramuscullary. hours 4 introductions intramuscullary.