Respiratory Distress Syndrome - Vydehi Institute of ... · Respiratory Distress Syndrome •...

Respiratory Distress Syndrome

IAP UG Teaching slides 2015‐16

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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


RDS / HMD

• Preterm, GA 28 – 32 wk• <28wk GA 60‐80% • 32‐36wk GA 15‐30% • 37wk‐term

• Predisposing factors – Prematurity Birth Asphyxia LSCS Male sex Maternal Diabetes Rh Negative


Pathogenesis

↓ Surfactant

Alveolar Atelectasis

Hyaline Membrane Formation

Fibrinous ExudatesInterstitial Edema

↓ Lung Compliance


Pathogenesis

- Transient Tachypnea- Asphyxia- Hypothermia- Apnea

↓pH, ↓PO2, ↑PCO2↓ Surfactant

RDS

Prematurity- Familial Predisposition- C-Section

Alveolar Hypoperfusion

RL Shunt

Pulm. Vasoconstr.

ShockHypovolemia

Atelectasis


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


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)


Differential Diagnosis

• Early onset sepsis / congenital Pneumonia

• TTNB

• CHD (TAPVC)


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


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 1/3rd 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


Investigations (cont…)

• Lamellar body counts (phospholipid “packages” produced by type2 alveolar cells) in amniotic fluid

• >50,000 lamellar bodies/μL → lung maturity


Investigations ‐ Contd..

• X‐Ray Chest:

• Reticulo granular pattern

• Air bronchogram

• Ground Glass opacity

• White wash appearance in severe RDS


X‐Ray ‐ RDS


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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 ScreeningIAP UG Teaching slides 2015‐16 1

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PREVENTION

• Induction of labour should preferably be delayed till lung maturity

• Prevent fetal asphyxia by antenatal & intranatal monitoring

• Antenatal Steroids (to Mother)• Betamethasone 12mg IM 2 doses in 24 hrs interval

(preferred)• Dexamethasone 4 doses in 12 hrs interval


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


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)


Surfactant therapy

• Given in to trachea

• Produces immediate improvement in lung condition

• Relatively costly drug

• No serious side effects in immediate period / long term


Supportive Rx

• Ventilatory Support ‐ CPAP & Positive pressure ventilation

• Maintain PaO2 50‐80 mm Hg (SpO2 85‐95%)

• Maintain PaCO2 45‐55 mm Hg

• O2 should be warm, humidified, & delivered by a blender

• Monitor O2 by concentration


Supportive Rx (Cont…)

• Shock – Fluids, inotropes

• Temperature Control

• Nutrition – TPN

• Sepsis Rx – Antibiotics till infection is ruled out

• Developmental friendly nursing policy


Complications

• Air leaks ‐ Pneumothorax, Pneumomediastinum, PIE, Pneumopericardium, Air Embolism

• PDA – look for & treat aggressively

• Infection – especially Nosocomial

• Intracranial hemorrhage – monitor USG

• Feed intolerance


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 10‐15%


RD score

1 2

RR 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


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