Objectives: Cardiac surgery-associated acute kidney injury occurs in up to 50% of patients and is associated with increased mortality and morbidity. This study aimed to discover if perioperative urinary alkalinization with sodium bicarbonate infusion reduces the prevalence of cardiac surgery-associated acute kidney injury.
Design: This study was a phase IIb multicenter double-blind randomized controlled trial.
Setting: This study was conducted in three tertiary hospitals in New Zealand and Australia.
Patients: A total of 427 patients scheduled to undergo elective cardiac surgery, who were at increased risk of development of cardiac surgery-associated acute kidney injury using recognized risk factors.
Measurements and main results: Patients were randomly allocated to receive either sodium bicarbonate (n = 215) or sodium chloride (n = 212) infusion, commencing at the start of anesthesia, in a dose of 0.5 mEq/kg/hr for the first hour and then 0.2 mmol/kg/hr for 23 hours. The primary outcome measure was the number of patients with development of cardiac surgery-associated acute kidney injury, defined as an increase in creatinine greater than 25% or 0.5 mg/dL (44 µmol/L) from baseline to peak value within the first five postoperative days. Significant differences among the groups in both plasma and urinary biochemistry were achieved 6 hours after commencement of the infusion, and these changes persisted for more than 24 hours. A total of 100 out of 215 patients (47% [95% CI, 40%-53%]) in the sodium bicarbonate group and 93 of 212 patients (44% [95% CI, 37%-51%]) in the sodium chloride group with development of acute kidney injury within the first five postoperative days (p = 0.58). There were also no significant differences in ventilation hours, ICU or hospital length of stay, or mortality.
Conclusions: Perioperative alkalinization of blood and urine using an infusion of sodium bicarbonate did not result in a decrease in the prevalence of acute kidney injury in patients following cardiac surgery.