CARDIORESPIRATORY EFFECTS OF INCREASED AIRWAY PRESSURE DURING CONTROLLED AND SPONTANEOUS BREATHING AFTER CARDIAC SURGERY

SUMMARY The cardiorespiratory effects of intermittent positive pressure ventilation with zero end-expiratory pressure (IPPV), continuous positive airway pressure breathing (CPAP) and spontaneous breathing (SR) were studied in 11 patients 3–20 h after open-heart surgery. The transition from IPPV to CPAP resulted in a significant reduction in tidal volume and significant increases in respiratory frequency, P a CO 2 , oxygen transport and mean arterial pressure, but there were no significant changes in cardiac output or P a O 2 . There were no significant differences in any of the measurements between CPAP and SR.