What condition is characterized by decreased surfactant and poor gas exchange in infants?

• A. Chronic obstructive pulmonary disease
• B. Infant respiratory distress syndrome
• C. Asthma
• D. Pneumonia

Answer: (B)

Infant respiratory distress syndrome (IRDS), also known as neonatal respiratory distress syndrome, is characterized by a deficiency of surfactant, a substance that reduces surface tension in the alveoli, the tiny air sacs in the lungs. Surfactant is critical for keeping the alveoli open during exhalation and preventing their collapse. In infants, especially those who are premature, the lungs may not produce enough surfactant, leading to atelectasis or collapse of the alveoli, which in turn impairs gas exchange and can result in significant respiratory distress.

In this condition, the poor gas exchange is due not only to the lack of surfactant leading to alveolar collapse but also to the subsequent decreased lung compliance. This means that more effort is required to inflate the lungs, which can lead to hypoxemia (reduced oxygen levels in the blood) and respiratory acidosis. The clinical presentation often includes rapid breathing, grunting, nasal flaring, and retractions, all signs of respiratory distress.

The other options listed—chronic obstructive pulmonary disease, asthma, and pneumonia—do not primarily stem from a surfactant deficiency. Chronic obstructive pulmonary disease typically involves airflow obstruction due to long-term lung damage, asthma pertains to