The influence of different ventilatory patterns on oxygenation and gas exchange after near-drowning.

After positive end-expiratory pressure (PEEP) valves for manually operated resuscitators became available it was of interest to find out whether PEEP should be applied at the scene of accident in nearly drowned patients. In 27 young pigs 25 ml of fresh water/kg body weight was instilled into the lungs via an endotracheal tube. After a period of apnoea (4 min) the pigs were ventilated artificially with 100% oxygen with either 5 cm PEEP or zero end-expiratory pressure (ZEEP). Within the PEEP group the AaDO2 returned to normal within the first 10 min after resuscitation, whereas the AaDO2 did not reach normal values for 2 h in the ZEEP group. The same observations were true for the PO2 values. Although the cardiac output decreased by almost 30% in the PEEP group, mean arterial pressures and heart rates remained unchanged. Lung weights and blood lactate concentrations confirmed that the same degree of water absorption and hypoxia had taken place in both groups. The conclusions from these experiments are that the application of 5 cm PEEP is part of the immediate measures of emergency treatment in nearly drowned victims.