Lack of Association Between Levels and Length of Intraoperative Controlled Hypotension and Acute Kidney Injury in Total Hip Arthroplasty Patients Receiving Neuraxial Anesthesia.

ABSTRACT

BACKGROUND AND OBJECTIVES: Previous research suggests that increased duration and lower levels of intraoperative hypotension (IOH) are associated with postoperative acute kidney injury (AKI). However, this association has not been evaluated in the context of intraoperative controlled hypotension (IOCH), a practice that has been linked in the past to improved outcomes with respect to blood loss and transfusion needs. This study aimed to investigate whether IOCH is associated with postoperative AKI among total hip arthroplasty patients at an institution where this technique is commonly practiced. METHODS: We performed a retrospective cohort study of 2431 unilateral total hip arthroplasty patients who received IOCH under neuraxial anesthesia as well as invasive arterial monitoring between March 2016 and January 2017. Multiple logistic regression was used to compute the adjusted odds ratios of postoperative AKI, adjusting for covariates including duration of intraoperative mean arterial pressure of less than 60 mm Hg. Sensitivity analyses also considered the effects of IOH defined at mean arterial pressure of less than 55 and less than 65 mm Hg. RESULTS: Acute kidney injury occurred in 45 (1.85%) of the 2431 patients in this cohort. Longer duration of hypotension was not associated with increased odds of postoperative AKI. Preexisting differences, such as compromised renal function, best predicted increased odds of AKI. CONCLUSIONS: In this study, AKI was rare. We found a lack of association between IOH and postoperative AKI in a setting where neuraxial anesthesia-facilitated IOCH is routinely practiced. Therefore, it seems prudent for future research and clinical guidelines to consider the distinction between inadvertent and controlled hypotension.