Key Point

Open-chest lung recruitment maneuvers produced declines in the central hemodynamics of cardiac surgery patients similar to those already reported for closed-chest lung recruitment maneuvers.

SAN FRANCISCO—Having already shown that closed-chest lung recruitment maneuvers (LRMs) adversely impact the central hemodynamics of cardiac surgery patients,¹ Danish researchers decided to evaluate the hemodynamic effects of lung recruitment before chest closure.² "As increased intrapleural pressure is thought to contribute to the cardiovascular impairment produced by positive pressure ventilation, we speculated that [open-chest] LRM would enhance central hemodynamics," the investigators said.

That did not occur, however. "LRMs with the chest open had similar negative effects on central hemodynamics as those performed with the chest closed," reported the investigators. "This finding indicates that compression of the alveolar capillaries due to lung expansion, impeding the outflow from the right ventricle, might be a more important reason for the circulatory effects by LRMs than the increase in pleural pressure."

In the study, nine cardiac bypass patients in American Society of Anesthesiologists physical classes I and II underwent an LRM (40 cm H2O of airway pressure for 15 seconds) before and after chest closure. Central hemodynamics were measured before, right after, and one minute after the maneuver. All patients received autologous blood transfusions to keep their hemodynamics stable during chest closure.

On average, the open-chest LRM produced cardiac output, arterial pressure, and heart rate declines of 50%, 26%, and 11%, respectively. Virtually the same reductions were seen with the closed-chest LRM; these averaged 46%, 26%, and 10%, respectively. Open- and closed-chest LRMs also produced mean declines in left ventricular end-diastolic area of 30% and 25%, respectively.

"One minute after the LRM, all measured variables had returned to baseline values," related the investigators. "No significant differences were found between open and closed-chest measurements before, at the end of, or one minute after the LRM."

—Timothy Begany

References
1. Nielsen J, Ostergaard M, Kjaergaard J, et al. Lung recruitment maneuver depresses central hemodynamics in patients following cardiac surgery. Intensive Care Med. 2005;31:1189-1194.
2. Nielsen J, Nygard E, Tingleff J, et al. Lung recruitment maneuver: open vs. closed chest. Presented at: annual meeting of the Society of Critical Care Medicine; January 10, 2006; San Francisco, Calif.

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