Reduction in the incidence of acute kidney injury after aortic arch surgery with low-dose atrial natriuretic peptide

BACKGROUND: Acute kidney injury (AKI) after surgery is associated with an increased risk of adverse events and death. Atrial natriuretic peptide (ANP) dilates the preglomerular renal arteries and inhibits the renin-angiotensin axis. A low-dose ANP infusion increases glomerular filtration rate after cardiovascular surgery, but it is not known whether it reduces the incidence of AKI or the mortality rate. OBJECTIVE: To evaluate whether an intravenous ANP infusion prevents AKI in patients undergoing aortic arch surgery requiring hypothermic circulatory arrest. DESIGN: A randomised controlled study. SETTING: Operating room and intensive care unit at Kawasaki Saiwai Hospital, Kanagawa, Japan. PATIENTS: Forty-two patients with normal preoperative renal function undergoing elective repair of an aortic arch aneurysm. INTERVENTION: Patients were assigned randomly to receive a fixed dose of ANP (0.0125 μg (-1) kg(-1) min) or placebo. The infusion was started after induction of anaesthesia and continued for 24 h postoperatively. MAIN OUTCOME MEASURES: The primary end-point was the incidence of AKI within 48 h after surgery. RESULTS: AKI developed in 30% of patients who received ANP compared with 73% of patients who received placebo (P = 0.014). Intraoperative urine output was almost 1 l greater in patients who received ANP (1865 ± 1299 versus 991 ± 480 ml in the control group, P = 0.005). However, there were no differences in mean arterial pressure or number of episodes of hypotension between the groups. Length of hospital and intensive care stays were not significantly different, nor was there a difference in 30-day mortality. No patients required haemodialysis or continuous renal replacement therapy. CONCLUSION: We found that an intravenous infusion of ANP at 0.0125 μg kg(-1) min(-1) is an effective intervention for reducing the incidence of postoperative AKI, and appears to afford a degree of renal protection during and after cardiovascular surgery. TRIAL REGISTRATION: Kawasaki ANP trial, UMIN Clinical Trials Registry ID: UMIN000011650.