Intraoperative hypotension and its association with acute kidney injury in patients undergoing elective cardiac surgery: a large retrospective cohort study

Intraoperative hypotension (IOH) is known to affect renal outcomes in noncardiac surgery. However, it is unclear whether intraoperative hypotension (IOH) causes postoperative acute kidney injury following cardiac surgery. This study aimed to determine whether the duration of IOH during cardiac surgery is associated with the incidence of postoperative acute kidney injury (AKI) and identify its impact on long-term outcomes. Retrospective cohort study. Academic university hospital (Heart and Diabetes Center, Bad Oeynhausen, Germany). A cohort of 28 909 patients who underwent elective cardiac surgery between 1 January 2009 and 31 December 2018. IOH was defined as intraoperative mean arterial blood pressure (MAP) of less than 60 mmHg for more than 2 min. The cumulative duration of these IOH events was recorded each patient. The primary outcome was the incidence of AKI according to the KDIGO criteria (Kidney Disease: Improving Global Outcomes). Logistic regression analysis was used to analyse the associations between IOH and the incidence of AKI. Secondary outcomes were the independent predictors for the incidence of AKI. Postoperative AKI was observed in 42.9% of patients. The cumulative duration of IOH (minutes) had a significant influence on the incidence of AKI [odds ratio (OR) 1.004; 95% confidence interval (CI) 1.003 to 1.005; P 0.001 versus P < 0.001). The survival time was significantly shorter in patients with a higher cumulative duration of IOH, patients aged more than 70 years, and those who developed AKI (P < 0.001). Logistic regression analysis identified eight predictors of AKI: age, cumulative duration of IOH, duration of surgery, chronic obstructive pulmonary disease, body mass index, type of surgery, American Society of Anesthesiologists stage, and Euroscore 2. The cumulative duration of IOH is an independent risk factor for the occurrence of postoperative AKI after cardiac surgery. Ethics Committee of the Ruhr University Bochum (Register number 2019-491).