Effects of PEEP on cardiovascular dynamics after open-heart surgery: a new postoperative monitoring technique.

The circulatory effects of incremental increases in positive end-expiratory pressure ventilation (PEEP) were assessed on 11 occasions in post-operative cardiac surgical patients by phasic aortic blood flow measurements and high-fidelity pressure recordings from which flow and pressure-flow derivatives of cardiac performance were calculated. At 15 cm H2O PEEP, mean arterial blood pressure was decreased by 10%, stroke volume and cardiac output by 15%, and peak left ventricular power by 21%. Although these indices promptly returned to control levels when PEEP was discontinued, levels of PEEP above 10 cm H2O should be used with caution for this group of patients.