Effect of low-dose ketamine on inflammatory response in off-pump coronary artery bypass graft surgery

Background. Off-pump coronary artery bypass graft surgery (OPCAB) is still associated with a marked systemic inflammatory response. The aim of this study was to investigate whether pre-emptive, low dose of ketamine, which has been reported to have anti-inflammatory activity in on-pump coronary artery bypass surgery, could reduce inflammatory response in low-risk patients undergoing OPCAB. Methods. In this prospective randomized-controlled trial, 50 patients with stable angina and preserved myocardial function undergoing OPCAB were randomly assigned to receive either 0.5 mg kg^-1 of ketamine (Ketamine group, n=25) or normal saline (Control group, n=25) during induction of anaesthesia. Inflammatory markers including C-reactive protein (CRP), interleukin (IL)-6, tumour necrosis factor-α (TNF-α), and cardiac enzymes were measured previous to induction (T1), 4 h after surgery (T2), and the first and second days after the surgery (T3 and T4). Results. There were no significant intergroup differences in the serum concentrations of the CRP, IL-6, and TNF-α and cardiac enzymes. Pro-inflammatory markers and cardiac enzymes, except TNF-α, were all increased after the surgery compared with baseline values in both groups. Conclusions. Low-dose ketamine administered during anaesthesia induction did not exert any evident anti-inflammatory effect in terms of reducing the serum concentrations of pro-inflammatory markers in low-risk patients undergoing OPCAB.