Neonatal Respiratory Distress Syndrome (NRDS): An Overview

Neonatal respiratory distress syndrome (NRDS), predominantly seen in premature infants, stands as a significant concern in neonatal medicine.

Characterized by insufficient surfactant production, NRDS prevents the lungs from functioning optimally, leading to serious breathing complications.

Understanding its causes, symptoms, and treatment options is pivotal for medical professionals and parents alike.

What is Neonatal Respiratory Distress Syndrome?

Neonatal Respiratory Distress Syndrome (NRDS) is a breathing disorder primarily seen in premature infants. It results from insufficient surfactant production, which leads to collapsed alveoli in the lungs. This hinders the baby’s ability to take in oxygen and release carbon dioxide, leading to breathing difficulties. Immediate medical intervention is often required.

Causes

Neonatal respiratory distress syndrome (NRDS) is primarily caused by an insufficient production of surfactant, a substance necessary for lung function.

Most commonly seen in premature infants, the underdeveloped lungs often don’t produce enough surfactant, leading to lung collapse.

Other causes include genetic factors, maternal diabetes, and delivery-related stress.

Additionally, cesarean deliveries, especially without labor, can increase the risk, as labor helps stimulate surfactant production in the fetus.

Signs and Symptoms

The signs and symptoms of neonatal respiratory distress syndrome (NRDS) usually manifest shortly after birth, often within the first few hours.

Some examples include:

• Rapid breathing
• Grunting during exhalation
• Nasal flaring
• Cyanosis
• Retractions
• Paradoxical chest movement
• Decreased breath sounds
• Lethargy
• Poor feeding

Note: It’s essential for healthcare providers to monitor newborns closely for these signs, especially if they’re premature or have other risk factors for developing NRDS. Immediate medical intervention can improve the prognosis and outcomes for these infants.

Treatment

Treatment for neonatal respiratory distress syndrome (NRDS) aims to support the infant’s breathing and boost surfactant production.

Some examples include include:

• Surfactant Replacement Therapy: Directly administering surfactant into the baby’s lungs to help them expand and function properly.
• Oxygen Therapy: Providing supplemental oxygen via a nasal cannula, mask, or a ventilator, depending on the severity.
• Continuous Positive Airway Pressure (CPAP): This method uses mild air pressure to keep the airways continuously open.
• Neonatal Mechanical Ventilation: For more severe cases, a machine can be used to assist or take over the baby’s breathing.
• High-Frequency Oscillatory Ventilation (HFOV): A type of mechanical ventilation that delivers very rapid small breaths to keep the baby’s lungs inflated.
• Supportive Care: This includes maintaining the infant’s body temperature, providing necessary nutrition, and treating any concurrent infections.
• Corticosteroids: Administered to the mother before delivery if premature birth is anticipated, these can accelerate the baby’s lung maturation.

Note: It’s crucial to provide these treatments in a neonatal intensive care unit (NICU) under the close supervision of specialized medical professionals. As with all treatments, the exact approach will depend on the individual needs of the infant.

What is Surfactant?

Surfactant is a complex mixture of lipids (primarily phospholipids) and proteins that play a crucial role in lung function.

It’s produced by type II alveolar cells in the lungs and serves several vital functions:

• Reduces Surface Tension: The primary role of surfactant is to lower the surface tension at the air-liquid interface within the alveoli, the tiny air sacs in the lungs. This prevents the alveoli from collapsing upon exhalation, ensuring that they remain open and can participate in gas exchange.
• Prevents atelectasis: Without surfactant, the alveoli would tend to collapse, a condition called atelectasis, making breathing difficult.
• Eases Breathing: By reducing surface tension, surfactant decreases the effort required to expand the lungs during inhalation.
• Host Defense: Some components of the surfactant have antimicrobial properties, playing a role in lung defense against pathogens.

In the context of neonatal medicine, a deficiency in surfactant production is a primary cause of neonatal respiratory distress syndrome (NRDS) in premature infants.

Their underdeveloped lungs might not produce enough surfactant, leading to difficulties in breathing post-birth. This is why surfactant replacement therapy is a common treatment for NRDS.

Neonatal Respiratory Distress Syndrome Practice Questions

1. What condition is characterized by the severe impairment of respiratory function in infants?
Neonatal Respiratory Distress Syndrome (RDS)

2. What is NRDS caused by?
Underdeveloped lungs

3. What is the reason for underdeveloped lungs?
The lack of surfactant

4. In the early 20th century, NRDS was characterized as what?
Hyaline membrane disease

5. What causes low alveolar compliance?
A decrease in surfactant

6. What is the biggest problem with NRDS?
Surfactant deficiency

7. What worsens gas exchange along with a thick alveolar-capillary membrane?
Increased distance between alveolar spaces and capillaries.

8. What is known as lung tissue underdevelopment?
Lung hypoplasia

9. What is the primary cause of respiratory distress?
Lung hypoplasia

10. What is a chemically complex agent whose main function is to stabilize the air-liquid interface of the alveoli and bronchioles and to lower surface tension?
Surfactant

11. What improves lung compliance?
Lower alveolar surface tension

12. What will happen if you have improved lung compliance?
Decreased work of breathing

13. At what gestational week will surfactant appear?
17-26

14. Which cells in the alveoli produce surfactant?
Type II Pneumocytes

15. What does surfactant do?
It decreases the alveolar surface tension, increases lung compliance, and decreases work of breathing.

16. What is the pathological cause of NRDS?
Pathology is due to a lack of surfactant due to the immaturity of the neonate’s lungs.

17. What will the chest x-ray show for an infant with NRDS?
You will likely see diffuse interstitial infiltrates.

18. Who is at risk for neonatal respiratory distress syndrome?
Pre-term infants (born before 35 weeks)

19. What are some other risk factors for neonatal respiratory distress syndrome?
Maternal diabetes and C-section delivery

20. During what stage of lung development do pneumocytes develop?
The saccular stage (week 26 to birth)

21. How do we test a pregnant mother to see if her baby’s lungs have reached maturity?
Look at the L:S ratio in the amniotic fluid.

22. What lecithin molecule is most important in surfactant?
Dipalmitoyl phosphatidylcholine

23. In NRDS, what is the L:S ratio?
Less than 1.5; A ratio of greater than 2.0 indicates a low risk for NRDS.

24. What happens to the oxygen tension in NRDS?
Oxygen tension is decreased.

25. Persistently low oxygen tension within the blood can result in an increased risk for what cardiac complication?
Patent ductus arteriosus

26. When is poor survival likely in neonates?
When they’re born before 24 weeks.

27. What are some interventions that can improve survival in neonates?
Administration of maternal steroids before birth to accelerate lung maturation, administration of artificial and exogenous surfactant after birth, and CPAP/intubation with oxygen support.

28. What are the complications of too much oxygen during the perinatal period?
Retinopathy, which is more involved with O2 tension; once the O2 is removed, the relative hypoxia in the eye causes blood vessel overgrowth, resulting in blindness. Intraventricular hemorrhage and bronchopulmonary dysplasia are other complications of too much oxygen.

29. Why does NRDS happen?
It occurs because of a deficiency of alveolar surfactant and is mainly seen in premature infants. It leads to alveolar collapse and reinflation with each breath, which exhausts the baby and causes respiratory failure.

30. What signs can result from hypoxia in NRDS?
Reduced cardiac output, hypotension, acidosis, renal failure, and death.

31. What are the signs of NRDS?
Respiratory distress shortly after birth (in the first 4 hours), tachypnoea, grunting, nasal flaring, intercostal retractions, and cyanosis.

32. What would you see on a CXR in NRDS?
Air bronchograms and diffuse granular patterns (i.e., ground glass appearance).

33. What are the differentials for NRDS?
Transient tachypnea of the newborn (due to excess lung fluid, normally resolves after 24 hours), meconium aspiration, congenital pneumonia, tracheoesophageal fistula, and congenital lung abnormalities.

34. How to prevent RDS?
Betamethasone or dexamethasone to all women at risk of premature delivery from 23-35 weeks.

35. How to treat RDS?
Delay cord clamping by 3 minutes in order to promote placenta-fetal transfusion. Provide oxygen via the oxygen/air blender at the lowest possible concentration. If the infant is breathing spontaneously, stabilize with CPAP. Provide surfactant if needed.

36. How would you manage a baby born before 26 weeks?
Intubate and provide prophylactic surfactant via the ET tube with ongoing doses if needed.

37. What is bronchopulmonary dysplasia?
A chronic lung disease in which premature infants are treated with supplemental oxygen and may require long-term oxygen therapy. It is more common in babies who are on prolonged mechanical ventilation for RDS.

38. What causes BPD?
Barotrauma and oxygen toxicity

39. What is seen on a chest x-ray of BPD?
CXR shows hyperinflation and rounded radiolucent areas, alternating with thin, denser lines.

40. What is the number one reason for admission to the NICU?
Respiratory distress

41. What are the most common causes of respiratory distress?
Respiratory distress syndrome (RDS), transient tachypnea of the newborn, pneumonia/aspiration syndromes, and pneumothorax.

42. What is a more specific indicator of lung maturity in babies?
Saturated phosphatidylcholine or phosphatidylglycerol

43. When are mature alveoli present?
36 weeks

44. What helps a neonate take a good first breath?
Vaginal delivery that causes intermittent compression of the thorax and helps with the removal of lung fluid. Surfactant helps to decrease surface tension which lowers the pressure needed to open the alveoli.

45. What tests must be performed on an infant with respiratory distress?
Chest x-ray, serum glucose, blood gas, CBC with differential, CRP, blood culture, obtain maternal history, and the details of labor and delivery.

46. What is respiratory distress syndrome formerly known as?
Hyaline membrane disease

47. When do we most often see respiratory distress syndrome?
60-80% of babies less than 28 weeks.

48. Which disease has a ground glass appearance on the x-ray?
Respiratory distress syndrome

49. What will the ABG of a child with respiratory distress syndrome show?
Hypoxemia, hypercapnia, and metabolic acidosis.

50. When do symptoms of respiratory distress syndrome appear?
Within minutes of birth and they worsen over time.

51. How do you treat respiratory distress syndrome?
IV fluids and keep the temperature within the normal range, keep oxygen between 85% and 95%, CPAP, endotracheal intubation, and surfactant replacement therapy.

52. What is the biggest complication of respiratory distress syndrome?
Chronic lung disease

53. What is the definition of bronchopulmonary dysplasia?
A breathing condition in infants where the lungs are not fully developed.

54. What is the persistent pulmonary hypertension of the newborn?
Inadequate ventilation that leads to impaired pulmonary transition; causes the release of pulmonary vasoconstrictor, and this leads to pulmonary hypertension.

55. What is the primary cause of respiratory distress syndrome?
Surfactant deficiency

56. What is the cause of transient tachypnea of the newborn?
Retained renal fluid

57. A radiograph that reveals increased interstitial markings with fluid in the interlobar fissures in an infant who has respiratory distress is most likely to represent?
Transient tachypnea of the newborn

58. The most likely diagnosis associated with the radiographic findings of a diffuse ground-glass appearance of the parenchyma in an infant who has respiratory distress is:
Hyaline membrane disease/RDS

59. What is sudden infant death syndrome?
Sudden unexplained death before 1 year of age, usually occurs in a previously healthy infant and the cause of death remains unexplained.

60. What is ECMO?
Extracorporeal membrane oxygenation (ECMO) is a life-saving technique that uses an external machine to take over the functions of the heart and lungs, providing oxygen to the body and removing carbon dioxide.

61. What are the types of surfactant?
Survanta, curosurf, and infasurf.

62. Should PEEP be used to treat infant respiratory distress syndrome?
Yes, PEEP is necessary to treat severe hypoxemia.

63. Which condition is a form of NRDS?
Hyaline membrane disease

64. Which abbreviations are associated with neonatal respiratory distress syndrome?
NRDS, IRDS, and HMD

65. Neonatal respiratory distress syndrome is similar to which disorder in adults?
Acute respiratory distress syndrome (ARDS)

Final Thoughts

The management and understanding of neonatal respiratory distress syndrome (NRDS) remain crucial in neonatal medicine.

Despite its prevalence, especially among preterm births, advancements in care have led to improved outcomes.

Continued research and early intervention strategies are essential to ensure the best possible prognosis for affected newborns.