Positive end-expiratory pressure. Effect on arterial oxygenation during respiratory failure in chronic obstructive...

Changes induced in arterial oxygenation by positive end-expiratory pressure (PEEP) were analysed in twenty-nine instances in seven patients with chronic obstructive airway disease and acute respiratory failure, who were receiving IPPV. A significant decrease in mean PaO2 was found 4 hours after the removal of PEEP (P smaller than 0-01), but after its addition during the same period the PaO2 change was not significant. PaCO2 values were not modified by PEEP. The slight increase in mean PaO2 (20-9 mmHg) encountered during controlled ventilation with PEEP seems of doubtful clinical value. Alveolar-arterial oxygen gradient, while breathing oxygen 100%, was found to be elevated with a mean value of 276 mmHg. It appears from our results that PEEP is of little or no value in the routine ventilatory treatment of patients with chronic obstructive airway disease unless hypoxaemia is believed to be caused by a large intrapulmonary shunt.