Respiratory Distress Syndrome | Medical Science Optional Notes for UPSC PDF Download

Respiratory Distress

• Indicators: Respiratory distress in a neonate is identified through various combinations of symptoms, including:
  • Tachypnea (respiratory rate >60/min)
  • Chest retractions
  • Grunting
  • Flaring of alae nasi
  • Cyanosis
• Possible Causes: Respiratory distress in neonates may stem from both respiratory and non-respiratory factors.

Most Common Causes of Respiratory Distress

• Respiratory Distress Syndrome (RDS):
  • A condition where the lungs of a newborn, particularly preterm babies, are insufficiently developed, leading to respiratory difficulties.
  • Commonly occurs in preterm infants.
• Meconium Aspiration Syndrome (MAS):
  • Involves the inhalation of meconium (fetal stool) by a term baby during delivery.
  • Results in respiratory distress within the first 24 hours after birth.
• Transient Tachypnea of Newborn:
  • Occurs in term infants within the first few hours of life.
  • Characterized by temporary rapid breathing.

Note: A term baby born to a mother with meconium-stained liquor may also develop respiratory distress within the first 24 hours.

Respiratory distress syndrome/Hyaline membrane disease

• Lipoprotein Nature: Surfactant is a lipoprotein composed of phospholipids, including phosphatidylcholine and phosphatidylglycerol, along with proteins.
• Cellular Source: Produced by type II alveolar cells within the lungs.
• Surface Tension Reduction: Essential for reducing surface tension in the alveoli.
• Onset of Production: Surfactant production commences around the 20th week of fetal life.
• Peak Production: Reaches its peak at 35 weeks of gestation.
• Risk of Respiratory Distress Syndrome (RDS): Neonates born before 35 weeks of gestation are at risk of developing RDS due to the incomplete development of surfactant.
• Basic Abnormality in RDS: RDS is characterized by surfactant deficiency as the fundamental abnormality.
• Ischemic Damage Consequence: Ischemic damage to the alveoli results in the transudation of proteins into the alveoli, forming hyaline membrane in RDS.

Clinical Features

• Manifestations: Tachypnea, retractions, grunting, cyanosis, and decreased air entry.
• Chest X-ray Findings: Reticulogranular pattern, ground glass opacity, low lung volume, white-out lungs.

Management

• Hospital Admission:
  • Admit in the Intensive Care Unit (ICU).
• Medical Interventions:
  • IV fluids and oxygen administration.
• Respiratory Support:
  • Mild to moderate RDS: Continuous positive airway pressure (CPAP).
  • Severe RDS: Mechanical ventilation (Note: Risk of complications such as retinopathy of prematurity and lung injury).
• Surfactant Supplementation:
  • Administered intratracheally in a rescue or prophylactic manner.
  • InSurE approach: Some neonates can be intubated, given surfactant, and rapidly extubated to CPAP, avoiding the need for mechanical ventilation in many cases.

Prevention of RDS

Antenatal Steroids:

• Administered to mothers in preterm labor (<35 weeks).
• Major breakthrough in preterm infant management.

Mechanism of Action

• Antenatal corticosteroids stimulate the development of type 1 and type 2 pneumocytes.
• Increases maximal lung volume, compliance, and gas exchange.
• Enhances production of surfactant proteins and phospholipid synthesis enzymes in type 2 pneumocytes, leading to increased surfactant production.
• Augments both endogenous and neonatal response to postnatal exogenous surfactant.

Benefits of Antenatal Glucocorticoids

• Reduces neonatal mortality by 40%.
• Decreases respiratory distress by 50%.
• Lowers the incidence of intraventricular hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, and hemodynamic instability.

Preferred Drugs

• Betamethasone and dexamethasone are the drugs of choice for antenatal corticosteroid use.
• Betamethasone is administered in two doses of 12 mg intramuscularly, 24 hours apart.
• Dexamethasone is given in four doses of 6 mg intramuscularly, 12 hours apart.

Complications

• Pneumothorax:
  • Accumulation of air in the pleural cavity, which can occur as a complication.
• Internal Bleeding:
  • Pulmonary and cerebral hemorrhage may occur.
• Bronchopulmonary Dysplasia (BPD):
  • A prolonged lung condition that may affect children with Neonatal Respiratory Distress Syndrome (NRDS).
  • Develops due to scarring caused by the ventilator used to treat NRDS, impacting lung development.
  • Symptoms include rapid, shallow breathing and shortness of breath.
• Developmental Disabilities:
  • Long-term consequences can lead to developmental disabilities such as learning difficulties, movement problems, impaired hearing, and impaired vision.
• Retinopathy of Prematurity/Retrolental Fibroplasia:
  • In utero, the fetus experiences a hypoxic state.
  • Premature birth stimulates the growth of retinal vessels through vascular endothelial growth factor (VEGF).
  • If the immature retina is exposed to ongoing hyperoxia after birth, vessel growth stops.
  • Over time, the avascular retina becomes ischemic, leading to the stimulation of VEGF, which can result in arterial venous shunts and neovascularization.

Respiratory distress syndrome-Repeat

Q1: A 20-year old primigravida delivered a preterm baby by normal vaginal delivery at 31 weeks of Gestation. The baby breathed and cried at birth. Weight was 1.1 kg. At 1 hour of age the baby was found to be in respiratory distress with Grunting (2009). 
(i) What is the likely diagnosis?
(ii) What are the complications of this condition?
(iii) How will you manage this baby? 

Q2: A 42 kg, 38 weeks gestation, male baby is born to a 28-year-old primigravida who has an unsupervised pregnancy by an emergency caesarean section. The child at 1 hour of age was noticed to have respiratory distress and blood glucose of 12 mg/dl. Discuss, in brief, the differential diagnosis and outline the key points in management of this child. (2010) 

Q3: Draw a flow diagram showing the pathophysiology of Respiratory Distress Syndrome in a newborn. Outline the measures to prevent RDS in a pregnant woman at 30 weeks of gestation, with 'threatened preterm labour. (2013) 

Q4: A newborn baby weighing 1.5 kg develops respiratory distress on the first day of life. (2015)
(i) List the differential diagnosis.
(ii) How would you assess this baby?
(iii) How would you manage the most common condition manifesting with respiratory distress in the newborn?

Q5: A baby is delivered at 34 weeks of gestation; develops respiratory distress soon after birth. (2017)
(i) List the important causes of respiratory distress in this baby.
(ii) Mention the pathogenesis of Respiratory Distress Syndrome.
(iii) Outline the management of the baby.

Q6: A 32-week preterm neonate born by a caesarian section is found to have a respiratory rate of 70/minute, grunting and cyanosis within half an hour of birth. What is the most diagnosis in this neonate? Describe the management of this condition. Write about its important complications? (2018)