Effect of asphyxia due to umbilical cord occlusion in the foetal lamb on leakage of liquid from the circulation and on permeability of lung capillaries to albumin.

1. Experiments were performed on foetal lambs, exteriorized at Caesarean section, to determine the effects of asphyxia on the leakage of liquid from the circulation and on the permeability of lung capillaries to albumin. Following a period of control observation (30-120 min) the foetus was asphyxiated by occlusion of the umbilical cord for 5-10 min and then allowed to recover while observations were continued for a further 20-80 min.2. Measurements were made of the lymph flow from the lungs, that had drained via the thoracic duct; of protein concentration in lymph and plasma; of arterial blood haematocrit, pH, P(O2) and P(CO2); and of arterial and left atrial pressures and heart rate. Human serum albumin labelled with (125)I was infused intravenously during the control period and (125)I count rates were followed in plasma and lymph throughout the experiment. Values for the transfer coefficient of albumin (E/V min(-1), i.e. interstitial fluid clearance of albumin per unit of lung interstitial fluid volume) were determined during control, cord-occlusion and post-occlusion periods.3. During cord occlusion arterial and left atrial pressure, haematocrit and plasma protein concentration all rose, returning to the control value by 20 min after release of cord occlusion. The haematocrit values indicated that about 9% of the blood volume was temporarily lost from the circulation. Lung lymph flow also increased, reaching a maximum in the 5 min period after release of occlusion and returning to the control level 15 min later. Values for E/V of albumin were at no time significantly different from those during the control period.4. It was concluded that acute foetal asphyxia produced by umbilical cord occlusion caused an increased leakage of liquid from the circulation in general. This effect was temporary and was probably due to an increase in capillary pressure during cord occlusion. The asphyxia had no persistent effect on the permeability of lung capillaries to albumin.