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.
1Cardiothoracic and Vascular Intensive Care Unit, Auckland City Hospital, Auckland, New Zealand.
2Department of Intensive Care, The Austin Hospital, Melbourne, Australia.
3The Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
4Department of Intensive Care, The Canberra Hospital, Canberra, Australia.
*See also p. 1802.
Supported, in part, by grants from the Intensive Care Foundation (Melbourne, Australia); Green Lane Research and Education Fund (Auckland, New Zealand); Austin Hospital ICU Research Fund (Melbourne, Australia); A+ Trust (Auckland, New Zealand). Research in the Cardiothoracic & Vascular ICU at Auckland City Hospital is partly funded by an unrestricted grant from Fisher and Paykel Healthcare (Auckland, New Zealand).
Dr. Bellomo holds a patent for urinary alkalinization to prevent acute kidney injury after cardiac surgery (United States Patent Application 20100266712). The remaining authors have disclosed that they do not have any potential conflicts of interest.
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