The Effects of On-Pump and Off-Pump Coronary Artery Bypass Surgery on Metabolic Profiles in the Early Postoperative Period

Abstract

Objective: Hyperlactatemia and base deficit (BD) are markers of adverse outcome after cardiac surgery, and their derangement can be influenced by the use of extracorporeal circulation. The authors hypothesized a better postoperative metabolic profile in off-pump coronary artery bypass grafting (OPCABG) compared with "on-pump" coronary artery bypass grafting (ONCABG).

Design: This was a retrospective study, with consecutive data collected for 1 year from electronic medical records.

Setting: Cardiothoracic intensive care unit at a tertiary university hospital.

Participants: The study comprised 339 patients who underwent elective coronary artery bypass grafting (ONCABG [n = 215], OPCABG [n = 124]).

Interventions: None.

Measurements and main results: The metabolic (arterial lactatemia, pH, and BD) and hemodynamic (inotropic/vasopressor support) parameters of OPCABG and ONCABG patients were compared at 7 predefined time points (intensive care admission and the 1st, 3rd, 6th, 12th, 18th, and 24th postoperative hours). For each output of interest, mixed-effects linear regression models were used (with time as random-effect to allow for clustering of repeated measures) and adjusted for a predetermined set of covariates. Arterial lactatemia and pH were comparable at all time points; BD was worse in the ONCABG group overall (p = 0.01) and at most time points (except at the 1st and 24th postoperative hours). For the whole period, inotropic support was more common in ONCABG patients (p<0.05), whereas vasopressor use was more frequent in the OPCABG group (p< 0.05).

Conclusions: Improved postoperative BD values were demonstrated in the OPCABG group, although pH and lactatemia were similar between groups. Inotropic support was less common in the OPCABG group at the expense of more frequent vasopressor support.

Keywords: acidosis; base excess; cardiac surgery; intensive care; lactates.