ABSTRACT 473

Abstract

Background and aims: One of the principal physiological processes of the immediate postnatal period is the rapid disappearance of the transpulmonary fluid. Delayed removal of the alveolar fluid results in neonatal respiratory distress. This process is mainly governed by the postnatal activation of the amilorid sensitive Na-channel (ENaC) and the basolateral Na+-K+-ATPase. The role of aquaporin (AQP) water channels was also suggested as AQP4 mRNA exhibits a sharp and transient rise on the first day of life. Aims: To highlight the potential role of AQP4 water channels in the reabsorption of fetal alveolar fluid based on the case of a neonate. Methods: A male neonate born by Caesarian section due to maternal neuroyelitis optica (NMO) was admitted at 38 weeks of gestation. Apgar scores were 6 and 9, birth weight was 3550 g. He developed a severe respiratory failure necessitating 100% FiO2 on HFOV, inhaled NO and repeated use of surfactant, without significant clinical effect. Infectious or developmental causes of RDS were excluded. Results: Serum AQP4 autoantibodies were tested because of maternal NMO at 1 week and after complete remission of the respiratory symptoms, at 3 weeks. The first result was positive, while AQP4 autoantibodies disappeared on the second test. Conclusions: The presented case is the first newborn in which AQP4 autoantibodies were transiently detected in the presence of spontaneously regressing severe respiratory failure. The defective function of these water channels is supposed to play a significant role in this unusual case of neonatal respiratory failure.