Neonatal Respiratory Distress & Fetal Lung Fluid | Pediatric Case Review MCQ

追加: 2026-06-03

[00:00:00]Case five. A 38-week gestation infant born via elective cesarean section without labor develops tachypnea within the first hour of life. The baby has mild subcostal retractions and nasal flaring, but remains alert and responsive. Chest x-ray shows hyperinflated lungs with prominent perihilar markings and fluid in the minor fissure. Which of the following best describes the primary pathophysiological mechanism responsible for this infant's respiratory distress?

[00:00:26]Option A, inadequate surfactant production leading to alveolar collapse.

[00:00:31]Option B, inflammatory response causing increased pulmonary vascular permeability. Option C, delayed clearance of fetal lung fluid from alveolar spaces. Option D, congenital structural abnormality of the respiratory tract. The correct answer is option C, delayed clearance of fetal lung fluid from alveolar spaces. During fetal life, the lungs actively secrete fluid to maintain expansion, driven by chloride secretion into the alveolar space. During labor, a catecholamine surge activates epithelial sodium channels, known as ENaC channels, which switch the epithelium from fluid secretion to active sodium reabsorption.

[00:01:09]Water follows sodium out of the alveoli, and residual fluid drains via lymphatic circulation. When cesarean delivery occurs without labor, this catecholamine surge is absent. The ENaC channels are not adequately activated, and fetal lung fluid remains in the alveolar spaces, impairing gas exchange.