Ventilation of liquid by the fetal lamb during asphyxia

¹ Department of Paediatrics, University College Hospital Medical School, and Department of Pharmacology, University College, London, England

Experiments were performed on fetal lambs, exteriorized by cesarean section, to study the ventilation of liquid during and after periods of umbilical cord occlusion. It was found that during and after the occlusion, the fetal lamb made strong ventilatory efforts with pleural pressures up to –68 cm H₂O, which resulted in the displacement of volumes up to 17 ml in a single gasp. The total amount of liquid ventilated during cord occlusion was less than during the ensuing recovery period, when episodes of regular breathing at frequencies up to 30/min occurred. The ventilation of liquid was limited mechanically by a high flow resistance and inertance. Estimates of the amount of mixing likely to take place between inspired liquid and lung liquid were made by the injection and withdrawal of aliquots of 0.9% NaCl containing tracer amounts of I¹³¹-labeled albumen. Although the amount of each injected sample which mixed with lung liquid was rather small, it could be estimated that the large number of breaths which occurred during recovery from asphyxia could cause significant washout of lung liquid.

Submitted on August 3, 1964