Higher arterial pressure during cardiopulmonary bypass may not reduce the risk of acute kidney injury

BACKGROUND: Acute kidney injury after cardiac surgery is common and associated with increased mortality. It is unknown whether an intended higher arterial pressure during cardiopulmonary bypass reduces the incidence of acute and chronic kidney injury. METHODS: Patients were randomised either to a control group or a high pressure group (arterial pressure > 60 mmHg). The inclusion criteria were age > 70 years, combined cardiac surgery and serum creatinine < 200 μmol/L. Glomerular filtration rate using the Cr-EDTA clearance method was measured the day before surgery and 4 months postoperatively. The RIFLE criteria were used to define the presence of acute kidney injury. In addition, the ratio between urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) and creatinine was measured. RESULTS: Ninety patients were included. Mean age was 76 ± 4 years and 76% were male. Mean arterial pressure was 47 ± 5 mmHg in the control group and 61 ± 4 mmHg in the high pressure group (p < 0.0001). The change in glomerular filtration rate at follow-up was − 9 ± 12 ml/min in the control group and − 5 ± 16 ml/min in the high pressure group (p = 0.288, 95% CI − 13 to 4). According to the RIFLE criteria 38% in the control group and 46% in the high pressure group developed acute kidney injury (p = 0.447). The postoperative urinary NGAL/creatinine ratio was comparable between the groups. CONCLUSIONS: An intended increase in arterial pressure during cardiopulmonary bypass to > 60 mmHg did not decrease the incidence of acute or chronic kidney injury after cardiac surgery. TRIAL REGISTRATION: Clinicaltrials.gov, identifier: NCT01408420. Registered 3rd of August 2011.