“Simple Strategy” Reduces AKI Risk during Cardiac Surgery

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A preoperative “remote ischemic preconditioning” step substantially lowers the risk of acute kidney injury (AKI) in high-risk cardiac surgery patients, reports a study in the Journal of the American Medical Association.

The randomized trial included 240 patients undergoing on-pump cardiac surgery at four German centers. All were considered at high risk for AKI based on a Cleveland Clinic Foundation score of 6 or higher. The intervention group underwent remote ischemic preconditioning, administered by blood pressure cuff inflation after the induction of anesthesia. The protocol consisted of three cycles of 5-minute ischemia and 5-minute reperfusion in one upper arm. Control individuals underwent a sham intervention.

Based on the Kidney Disease: Improving Global Outcomes criteria, AKI occurred in 37.5 percent of patients assigned to remote ischemic preconditioning versus 52.5 percent of control individuals. Preconditioning was also associated with less need for renal replacement therapy: 5.8 versus 15.8 percent, and less time in the intensive care unit, 3 days versus 4 days.

There was no difference in stroke, myocardial infarction, or death. The release of two AKI biomarkers, urinary insulin-like growth factor–binding protein 7 and tissue inhibitor of metalloproteinases 2, was reduced in the intervention group. There were no reported adverse events.

Remote ischemic preconditioning may activate natural defense mechanisms that can protect the kidney during subsequent inflammatory or ischemic stress. Previous small studies of remote ischemic preconditioning to prevent AKI have yielded conflicting results.

This multicenter trial showed a 15 percent absolute reduction in AKI among high-risk cardiac surgery patients undergoing remote ischemic preconditioning. The authors call for further study of this “simple and promising strategy” to protect the kidneys and improve postoperative outcomes [Zarbock A, et al. Effect of remote ischemic preconditioning on kidney injury among high-risk patients undergoing cardiac surgery: a randomized clinical trial. JAMA 2015; 313:2133–2141].