Respiratory Distress Syndrome IAP UG Teaching slides 2015

Respiratory Distress Syndrome IAP UG Teaching slides 2015 -16 1

What the Medical student or primary care physician should know • Purpose: • Simple intervention CPAP can save many preterm babies with moderately severe RDS • Surfactant therapy – cost effective / life saving • ANS – prevention of RDS • Detailed – skill to be acquired • ANS • RD scores • Basic knowledge IAP UG Teaching slides 2015 -16 2

Respiratory Distress Syndrome • Respiratory distress due to ↓surfactant • Most common cause of RD in premature • • PRIMARY - Prematurity Genetic • • SECONDARY - Meconium Aspiration Lung insult-Asphyxia IAP UG Teaching slides 2015 -16 3

RDS / HMD • Preterm, GA 28 – 32 wk • <28 wk GA 60 -80% • 32 -36 wk GA 15 -30% • 37 wk-term • Predisposing factors – Prematurity Birth Asphyxia LSCS Male sex Maternal Diabetes Rh Negative IAP UG Teaching slides 2015 -16 4

Pathogenesis ↓ Surfactant Alveolar Atelectasis Fibrinous Exudates Interstitial Edema Hyaline Membrane Formation ↓ Lung Compliance IAP UG Teaching slides 2015 -16 5

Pathogenesis - Transient Tachypnea Prematurity - Asphyxia - Familial - Hypothermia Predisposition - Apnea - C-Section ↓p. H, ↓PO 2, ↑PCO 2 Atelectasis ↓ Surfactant RL Shunt Pulm. Vasoconstr. Hypovolemia Alveolar Hypoperfusion Shock IAP UG Teaching slides 2015 -16 RDS 6

Clinical Features • Usually a Preterm Baby • Respiratory Distress within 6 hrs of Life (usually within minutes of birth) • SCR, ICR, Grunting, Cyanosis, Ala nasi Flaring*. • Auscultation: ↓ air entry ± fine rales • Apnea in extreme prematurity • Shock • Other features: Edema, ileus, & oliguria IAP UG Teaching slides 2015 -16 7

Clinical Course • Severe cases develop respiratory failure needing ventilation / surfactant / CPAP – and may tire and develop apnea / die if care not offered • Mild cases – can be managed with only oxygen • Symptoms progress to peak in 3 days • Improvement thereafter (often heralded by spontaneous diuresis) IAP UG Teaching slides 2015 -16 8

Differential Diagnosis • Early onset sepsis / congenital Pneumonia • TTNB • CHD (TAPVC) IAP UG Teaching slides 2015 -16 9

Investigations • Amniotic fluid – Lecithin to Sphingomyelin ratio • (L/S) ratio • >2. 5 = 0. 5%, >2 =10% , • 1. 5 -2 = 15 -20%, <1. 5 = 60% risk of developing RDS • Blood & Meconium depress mature L/S ratio and may elevate immature ratio • Exceptions : IDM, Asphyxia- can develop RDS even if ratio ok • Phosphatidylglycerol = present • Saturated Phosphatidylcholine (SPC) > 500 ug/dl IAP UG Teaching slides 2015 -16 1 0

Investigations – Cont. . . Gastric Aspirate – Shake Test • Mix 0. 5 ml of gastric aspirate & 0. 5 ml of absolute alcohol • Shake for 15 seconds & allow the solution to settle for 15 seconds • If no bubbles – 60 % chances of RDS • Small bubbles to the extent of 1/3 rd of the circle of the test tube – 20% chances of RDS • All around the circle – bubbles in two circle in some places – bubbles in two row & above <1% chances of RDS IAP UG Teaching slides 2015 -16 1 1

Investigations (cont…) • Lamellar body counts (phospholipid “packages” produced by type 2 alveolar cells) in amniotic fluid • >50, 000 lamellar bodies/μL → lung maturity IAP UG Teaching slides 2015 -16 1 2

Investigations - Contd. . • X-Ray Chest: • Reticulo granular pattern • Air bronchogram • Ground Glass opacity • White wash appearance in severe RDS IAP UG Teaching slides 2015 -16 1 3

X-Ray - RDS IAP UG Teaching slides 2015 -16 1 4

Investigations – Cont. . . Related to Acute Care & DD • Blood Gases – hypoxia and hypercarbia • Echo – for associated PDA / exclude CHD • Supportive care • Cranial Ultra sonography • Blood Chemistry • Sepsis Screening IAP UG Teaching slides 2015 -16 1 5

PREVENTION • Induction of labour should preferably be delayed till lung maturity • Prevent fetal asphyxia by antenatal & intranatal monitoring • Antenatal Steroids (to Mother) • Betamethasone 12 mg IM 2 doses in 24 hrs interval (preferred) • Dexamethasone 4 doses in 12 hrs interval IAP UG Teaching slides 2015 -16 1 6

Antenatal steroids • Must be given to all mothers in preterm labor (<37 weeks) • Decreases incidence of severe RDS, IVH, mortality by half • Can be given even if mother has HTN, diabetes IAP UG Teaching slides 2015 -16 1 7

Treatment SPECIFIC – Surfactant Therapy • Types of surfactants: • Natural – Bovine, Calf, Porcine • Synthetic • Timing of intervention: • Prophylaxis (before onset of RD) • Treatment (rescue – after onset of RD) IAP UG Teaching slides 2015 -16 1 8

Surfactant therapy • Given in to trachea • Produces immediate improvement in lung condition • Relatively costly drug • No serious side effects in immediate period / long term IAP UG Teaching slides 2015 -16 1 9

Supportive Rx • Ventilatory Support - CPAP & Positive pressure ventilation • Maintain Pa. O 2 50 -80 mm Hg (Sp. O 2 85 -95%) • Maintain Pa. CO 2 45 -55 mm Hg • O 2 should be warm, humidified, & delivered by a blender • Monitor O 2 by concentration IAP UG Teaching slides 2015 -16 2 0

Supportive Rx (Cont…) • Shock – Fluids, inotropes • Temperature Control • Nutrition – TPN • Sepsis Rx – Antibiotics till infection is ruled out • Developmental friendly nursing policy IAP UG Teaching slides 2015 -16 2 1

Complications • Air leaks - Pneumothorax, Pneumomediastinum, PIE, Pneumopericardium, Air Embolism • PDA – look for & treat aggressively • Infection – especially Nosocomial • Intracranial hemorrhage – monitor USG • Feed intolerance IAP UG Teaching slides 2015 -16 2 2

Outcome in the Survivors • • • Survival rates near 100 % with CPAP / ventilation and surfactant in babies > 28 weeks / 1000 gms No increased respiratory morbidity in future except in extreme preterm • In ELBW Bronchopulmonary dysplasia (BPD) (dependant on oxygen or respiratory support for prolonged period) 5 -30% Co-existing morbidities in very preterm • Retinopathy of prematurity (ROP) of <1250 g 7% • Neurologic impairment – related to PVL, IVH, prematurity 1015% IAP UG Teaching slides 2015 -16 3

RD score RR 1 2 60 -80 >80 Retractions None Mild- mod Severe Grunting None Audible by steth Audible without steth Breath sounds Good Decreased Very poor Saturation Without oxygen With < 40 % oxygen High oxygen need IAP UG Teaching slides 2015 -16 2 4

IAP UG Teaching slides 2015 -16 2 5