Effects of early vital capacity maneuver on respiratory variables during multivessel off-pump coronary artery bypass graft surgery

OBJECTIVES:: Despite avoiding cardiopulmonary bypass, similar degrees of pulmonary impairment compared with on-pump coronary artery bypass surgery have been demonstrated in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB) compared with on-pump coronary artery bypass surgery. To investigate the effects of an early vital capacity maneuver (VCM) on intrapulmonary shunt (Qs/Qt), oxygenation, and pulmonary outcome in OPCAB. DESIGN:: Prospective, randomized, controlled, double-blind clinical trial. SETTING:: Cardiothoracic operating room and intensive care unit (ICU) of a university hospital. PATIENTS:: Fifty patients scheduled for OPCAB were randomized to treatment with VCM or none. INTERVENTIONS:: After sternotomy, VCM was performed by inflating the lungs to 40 cm H2O and holding this pressure for 10 seconds. MEASUREMENTS AND MAIN RESULTS:: Qs/Qt, Pao2/Fio2 (P/F) ratio, and dynamic and static pulmonary compliances were measured before induction of anesthesia (T0), 15 minutes after tracheal intubation (T1), during Y-graft construction (T2), 15 minutes after completion of grafting (T3), 15 minutes after sternal closure (T4), and 3 hours after arrival at the ICU (T5). Qs/Qt was lower and P/F ratio was higher in the VCM group at T2 through T5. Pulmonary compliances were also higher in the VCM group at T4 and T5. Patients in the VCM group were extubated earlier. CONCLUSIONS:: The beneficial effects of an early VCM on Qs/Qt persisted into the period of ICU care, with an improvement in P/F ratio and preserved pulmonary compliances, leading to a shorter time to extubation.