Respiratory Distress Syndrome

 Respiratory Distress Syndrome

Respiratory distress syndrome also called hyaline membrane disease.

Syndrome in premature infants caused by developmental insufficiency of surfactant production and structural immaturity of lungs.

Surface surfactant helps in maintaining alveolar stability.

Surfactant deficiency; due to lack of lungs development cause respiratory distress. Respiration become labored.

Types of surfactant

1. Type l

2. Type ll

3. Macrophages

Type 1 (Pneumocytes)

Cells line the alveoli and present in inner surface of lungs.

Alveoli surface lined by Type l.

2. Type ll (Pneumocytes)

Synthesizing and secreting pulmonary surfactant.

Function of Surfactant

Reduce surface tension of lungs and maintain alveolar stability at low pressure.

So, alveoli not collapse at the end of expiration.

Pathophysiology

Lungs and alveoli collapse with expirations.

Neonates has exert as much effort with each Respiration.

(Necessary first breath after birth)

Primary vascular resistance increases as lungs are collapsed and pulmonary hypoperfusion.

Hypoxia and hypercapnia occur due to progressive atelectasis and pulmonary hypoperfusion.

Hypoxia continues anaerobic glycolysis occur for production of glucose from glycogen. Resulting in lactic acid production causing metabolic acidosis.

Increase pulmonary vascular spasm/ pulmonary hypoperfusion leads to necrosis of alveoli and reduces surfactant production.

Necrosis leads to formation of cement like hyaline membrane inside lungs.

Which makes lungs stiff and inelastic, Inhibiting gas exchange in lungs.

Make worsen condition of children.

Decrease surfactant - decrease ability to stretch and expand alveoli - decrease alveolar ventilation - decrease pulmonary blood flow

Clinical features

1. Tachypnea

2. Tachycardia

3. Chest wall retraction

4. Expiratory grunting

5. Nasal flaring

6. Cyanosis

7. Prolonged cessation of breathing, metabolic acidosis.

8. Hypoxia

Diagnostic Evaluation

1. Child history taking and physical examination

RDS experiencing breathing difficulty at birth within 2 hours after birth.

Silverman Retraction Score

Method of assessing severity of Respiratory distress

Most common sign of abnormal ventilation is tachypnea (RR>60 breaths/min)

Grunting on expiration, nasal flaring present; indicate Respiratory distress.

Auscultation of chest reveal; diminished breath sound

Flaccid hypoactive and motionless

Frog-legged position.

2. Chest X- ray

Shows areas of atelectasis

3. Air bronchogram

Shows air filled bronchi

4. Aterial blood gas analysis;

Monitor the ABG analysis;

PCo2; >65mmHg

PO2; 40mmHg

HCO3-; below 7.15 milliequivalents per liter (mEq/L)

Normal value of PaO2; 75-100mmHg

Normal value of PaCO2; 35-45 mmHg

Normal value of Bicarbonate (HCO3): 22-26 mEq/L

Normal value to oxygen saturation; 95 to 100 percent

Normal value of blood pH: 7.35-7.45

5. Shake test

Done on gastric aspiration withdrawn from Neonate in first hours of life.

Normal saline 0.5 ml is mixed with 0.5 ml of gastric aspirate.

Resulting 1ml.

Added to 1ml of 95% ethanol.

Mixture is shaken well for 15 second kept aside.

After 15 minutes, test tube viewed against black background .

A complete ring of bubbles is seen on meniscus; means positive test; indicates surfactant present and baby normal.

Absence or incomplete of bubble or ring of bubbles on meniscus; indicate negative test

Surfactant deficiency; infant has RDS.

4. Prenatal diagnosis of RDS

L/S ratio;

Made by determining lecithin/ sphingomyclin ratio in amniotic fluid.

L/S ratio more than 2 indicates adequate lung maturity.

L/S ratio les than 2 significant for immature fetal lung development.

Management

Respiratory distress; threatening emergency in premature Newborn.

1. Improving ventilation to enhance oxygenation.

2. Correction of acidosis

3. Maintenance of thermo neutral environment

4. Adequate nutrition

Management of Baby with RDS

1. Monitoring baby condition

1. Rectal or skin temperature noted hourly

2. Respiratory rate hourly monitoring

3. Retraction and Grunting observed

4. Status of peripheral pulse and blood pressure

5. Skin color

6. Apneic episodes

7. Activity, responsiveness and cry of baby

8. Urine output monitored

2. Intravenous infusion for nutritional status of baby

Oral feeding; risk of aspiration

Administered nasogastric feeding or total parenteral nutrition (TPN).

3. Administer sodium bicarbonate therapy

Dose 3-8mEq/kg in 24 hours or dose of soda bicarb calculated according to baby's PH.

3. Ventilatory Support

Administration oxygen under PPV; prevent alveolar collapse and ensure gas exchange.

CPAP (continuous positive airway pressure).

Useful in infant with decreased lung compliance.

CPAP started; PO2 remains below 50mmHg.

If 100% oxygen therapy or CPAP, PO2 remain below 50 mmGHg.

Assisted ventilation required.

Assisted ventilation with positive end expiratory pressure (PEEP) in recommended to prevent collapse of lung alveoli at end of expiration.

On recovery infant is gradually weaning to SIMVI mode folloewed by CPAP.

If baby in ventilator;

Oropharyngeal and tracheal suctioning and chest physiotherapy done.

4. Oxygen via hood

After weaning the baby from ventilation

Oxygen Administration via hood, maintain PaO2; between 50-80mmHg or oxygen saturation 90-95%.

5. Warmth and Humidity

Maintained skin temperature; 36.5 degree Celsius

Keeping baby incubator/ radiant warmer

Thermoneutral environment having humidity 40-60%.

6. Surfactant therapy

Prevention and management of respiratory distress

Surfactant administered intratracheally via ET tube in doses of 100mg/ kg body weight.

7. Antibiotics

Prevent pulmonary infection. (Due to invasive procedure)

Septic screening

Periodic screening from endotracheal tube.

Blood culture 

7.  Administration of vitamin E

Treatment of RDS; require administration of high concentration oxygen.

Lead to development of bronchopulmonary dysplasia;BPD and Retrolental fibroplasia (ratinopathy of prematurity; ROP).

Vitamin E; antioxidant

Inhibit peroxidation of membrane lipids

Reducing chances of ROP and BPD

8. For low birth weight baby or pre term baby

Efficient oxygen therapy may administered.

Vitamin E is dose of 100IU/kg/day intramuscularly (IM) from birth onwards.

Nursing Management

1. Prevention from infection

Preterm with RDS;

Isolation

Aseptic precautions

2. Minimally handnle

Critically ill infant

3. Position with head elevated, to reduce pressure on diaphragm.

4. Airway kept patent, and opened by extending head slightly.

Done by placing folded sheet or towel under baby shoulder.

5. Oxygen Administration for long duration via face mask or nasal prongs.

Soothing antibiotic ointment applied to irritant skin surface.

6. Keep warm baby by placing in incubator/ radiant warmer

7. Manitain vital sign

8. Endotracheal suctioning, strict aseptic technique used.

9. Mataintain oxygen saturation while suctioning baby.

10. Measure weight of baby to assess adequacy of fluid administration.

11. Administer IV/NG feed/Medication prescribed by physician.