Answer: b) Surfactant administration and oxygen therapyRESPIRATORY DISTRESS SYNDROME/HYALINE MEMBRANE DISEASEIncidence: overall 15-30%60-80% of infants less than 28 wks of gestational age15-30% of those between 32 and 36 wks5% beyond 37 wksRarely at termHighest in preterm male or white infantsIncreased incidence of HMDReduced risk of HMD* Infants of diabetic mothers* Delivery < 37 weeks* Multifetal pregnancies* Cesarean section delivery* Male gender* Precipitous delivery* Asphyxia, Cold stress* History of previously affected infants* Chronic or pregnancy-associated hypertension* Maternal opiate addiction* Prolonged rupture of membranes* Antenatal corticosteroid useEtiologyBasic abnormality is the surfactant | (SP-B & SP-C) that helps reducing surface tension in the alveoli.In the absence of surfactant surface tension | and alveoli tend to collapse during expirationSurfactant production starts around 20 weeks gestationIt appears in amniotic fluid between 28 and 32 weeks and peaks at 35 weeks Clinical featuresThe infant is almost always preterm but has weight appropriate for gestational ageSigns of HMD usually appear within minutes of birthHypoxemia and acidosis result in pulmonary vasoconstriction and R-L shunt across the foramen ovaleCharacteristically, tachypnea, prominent (often audible) grunting, intercostal and subcostal retractions, nasal flaring, and duskiness are notedCyanosis increases and is often relatively unresponsive to oxygen administrationMixed respiratory-metabolic acidosis, edema, ileus, and oliguria are other featuresDeath is rare on the 1st day of illness, usually occurs between days 2 and 7, and is associated with alveolar air leaks (interstitial emphysema, pneumothorax) and pulmonary hemorrhage or IVH.DiagnosisCharacteristic histological manifestation is diffuse alveolar damageX-ray shows reticulo-granular pattern, ground glass opacity, low lung volume, air bronchogram (more prominent early in the left lower lobe)and white out lungs in severe diseasePrenatal diagnosis - lecithin/sphingomyelin ratio in the amniotic fluid. Ratio > 2 - adequate lung maturityDipalmitoyl phosphatidylcholine (lecithin) levels are low in amniotic fluidSimple bedside test, the shake test can be done on the amniotic fluid or the gastric aspirate mixed with absolute alcohol. Bubbles formation indicates lung maturityLungs - normal size, solid, airless, and reddish purple, similar to the color of the liver, and sink in waterRespiratory distress score (Downe score): Mild < 5; moderate 5-8; severe RD > 8Score012Respiratory rate40-60/min60-80/min> 80/minOxygen requirementNone< 50%> 50%RetractionsNoneMild to moderateSevereGruntingNoneWith stimulationAt restBreath soundsNormalDecreasedBarely heardTreatmentMild to moderate: Continuous Positive Airway Pressure(CPAP) a noninvasive method where a pressure of 5-7 cm of water applied at nostril to keep the alveoli openSevere: Synchronized intermittent mandatory ventilation (SIMV)Exogenous surfactant is now recommended. Administered intratracheallyGiving surfactant and then CPAP immediately (InSurE approach) is showing promising resultsProphylaxis: for babies < 27 weeks surfactant given via endotracheal tube within 2hrs of birthGood prognosis if managed appropriately.Survival rate is 90% in very low birth weight babies (<1500g)In the absence of ventilator support, most neonates with severe disease will diePrevention: Inj.Betamethasone 48 hr before the delivery of fetuses between 24 and 34 wk of gestationDecreases the incidence of* Mortality and morbidity in HMD* Intra Ventricular Hemorrhage* PDA* Pneumothorax* Necrotizing enterocolitisIndications* All women with preterm labor between 24 and 34 weeks of gestationContraindication* Clinical chorioamnionitis* EclampsiaMaternal hypertension and DM are not contraindications