Sodium bicarbonate does not prevent postoperative acute kidney injury after off-pump coronary revascularization: a double-blinded randomized controlled trial

Background: Acute kidney injury (AKI) is a common morbidity after off-pump coronary revascularization. We investigated whether perioperative administration of sodium bicarbonate, which might reduce renal injury by alleviating oxidative stress in renal tubules, prevents postoperative AKI in off-pump coronary revascularization patients having renal risk factors. Methods: Patients (n=162) having at least one of the following AKI risk factors were enrolled: (i) age >70 yr; (ii) diabetes mellitus; (iii) chronic renal disease; (iv) congestive heart failure or left ventricular ejection fraction <35%; and (v) reoperation or emergency. Patients were evenly randomized to receive either sodium bicarbonate (0.5 mmol kg(-1) for 1 h upon induction of anaesthesia followed by 0.15 mmol kg(-1) h(-1) for 23 h) or 0.9% saline. Acute kidney injury within 48 h after surgery was assessed using the Acute Kidney Injury Network criteria. Results: The incidences of AKI were 21 and 26% in the bicarbonate and control groups, respectively (P=0.458). Serially measured serum creatinine concentrations and perioperative fluid balance were also comparable between the groups. The length of postoperative hospitalization and incidence of morbidity end points were similar between the groups, whereas significantly more patients in the bicarbonate group required prolonged mechanical ventilation (>24 h) relative to the control group (20 us 6, P=0.003). Conclusions: Perioperative sodium bicarbonate administration did not decrease the incidence of AKI after off-pump coronary revascularization in high-risk patients and might even be associated with a need for prolonged ventilatory care.