Open lung ventilation improves functional residual capacity after extubation in cardiac surgery

After cardiac surgery, functional residual capacity (FRC) after extubation is reduced significantly. We hypothesized that ventilation according to the open lung concept (OLC) attenuates FRC reduction after extubation.

A prospective, single-center, randomized, controlled clinical study.

Cardiothoracic operating room and intensive care unit of a university hospital.

Sixty-nine patients scheduled for elective coronary artery bypass graft and/or valve surgery with cardiopulmonary bypass.

Before surgery, patients were randomly assigned to three groups: (1) conventional ventilation (CV); (2) OLC, started after arrival in the intensive care unit (late open lung); and (3) OLC, started directly after intubation (early open lung). In both OLC groups, recruitment maneuvers were applied until Pao2/Fio2 was >375 Torr (50 kPa). No recruitment maneuvers were applied in the CV group.

FRC was measured preoperatively and 1, 3, and 5 days after extubation. Peripheral hemoglobin saturation (Spo2) was measured daily till the third day after extubation while the patient was breathing room air. Hypoxemia was defined by an Spo2 value < or =90%. Averaged over the 5 postoperative days, FRC was significantly higher in the early open lung group and tended to be higher in the late open lung group, in comparison with the CV group (mean +/- sem: CV, 1.8 +/- 0.1; late open lung,1.9 +/- 0.1; and early open lung, 2.2 +/- 0.1l). In the CV group, 37% of the patients were hypoxic on the third day after extubation, compared with none of the patients in both OLC groups.

After cardiac surgery, earlier application of OLC resulted in a significantly higher FRC and fewer episodes of hypoxemia than with CV after extubation.