Hemodynamic effect of sustained pulmonary hyperinflation in patients after cardiac surgery: open vs. closed chest

In a previous study, we showed that sustained pulmonary hyperinflation, i.e. a lung recruitment maneuver, after closure of the chest in patients undergoing cardiac surgery had significantly negative effects on the central hemodynamics. As elevated pleural pressure is believed to be a major cause of this cardiovascular impairment, we hypothesized that performing the sustained pulmonary hyperinflation under open chest conditions would affect the circulation less.

Patients undergoing cardiac by-pass surgery were included and sustained pulmonary hyperinflations (40 cmH(2)O airway pressure for 15 s) were performed immediately before and after closure of the sternum. Pulse contour cardiac output, heart rate, mean arterial pressure and pulse pressure variation were measured before, during and 1 min after the hyperinflations. Left ventricular dimensions were measured using trans-esophageal echocardiography.

Cardiac output (CO) and mean arterial blood pressure (MAP) decreased significantly during the sustained pulmonary hyperinflation both with an open and closed chest (in parenthesis): CO by 50 (45)% and MAP by 19 (24)%. The left ventricular end-diastolic area was significantly reduced by 24 (33)%. One minute after the hyperinflation, all measured variables had returned to baseline values. No significant differences in the measured variables were found between the two conditions before, during or 1 min after the hyperinflation.

Contrary to our hypothesis, sustained pulmonary hyperinflations with the chest open, i.e. before sternal closure, had similar negative effects on central hemodynamics as those performed with the chest closed, i.e. after sternal closure.