Association of exposure below various thresholds of hemodynamic parameters during cardiopulmonary bypass with acute kidney injury.

INTRODUCTION

This study aimed to investigate the association of exposure below various thresholds of mean arterial pressure (MAP), pump flow rates, and hemoglobin levels during cardiopulmonary bypass (CPB) with cardiac surgery-associated acute kidney injury (CSA-AKI).

METHODS

Adult patients undergoing cardiac surgery with CPB at a university hospital between April 2015 and August 2023 were included. The primary outcome was CSA-AKI within 7 days postoperatively. The primary exposures were the area under the threshold (AUT) of MAP, pump flow rate, and Hb during CPB. A multivariable logistic regression using covariates selected via Lasso regularization estimated the adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

We finally analyzed 333 patients, of which 156 patients (46.8%) developed CSA-AKI. The AUT of hemoglobin, but not those of MAP and pump flow rate, was associated with CSA-AKI. The lower the threshold, the stronger the association (<8 g/dL, aOR = 1.132 per 10 g/dL × min, 95% CI = 1.036-1.243, p = 0.007; <9 g/dL, aOR = 1.048, 95% CI = 1.013-1.086, p = 0.007; and <10 g/dL, aOR = 1.027, 95% CI = 1.007-1.048, p = 0.010).

CONCLUSION

Hemoglobin levels during CPB below 8.0 g/dL were associated with CSA-AKI, while MAP and pump flow rates indicated no such association.