Positive end-expiratory pressure. Immediate haemodynamic effects during artificial ventilation.

The immediate haemodynamic effects of the addition of a positive end-expiratory pressure (PEEP) of 5 cmH2O has been studied in eleven patients undergoing artificial ventilation for respiratory failure. Mean cardiac output fell from 6.0 to 5.5 litres/min. This was due to a similar decrease in stroke volume. Individual patients showed greater, though short-lived, changes. There was also a statistically significant increase in central venous pressure (from 8-9 cmH2O) and peripheral resistance (from 1280 to 1380 dyn sec cm-5) associated with the application of PEEP. Overall changes in heart rate and mean arterial blood pressure were insignificant. Arterial oxygen tension increased in the majority of patients but the mean figure was unchanged. Mean oxygen delivery to the tissues fell from 830 to 780 ml/min.