Intraoperative hypotension and the risk of acute kidney injury following liver transplantation

Background: Acute kidney injury (AKI) is a frequent adverse outcome following liver transplantation (LT) with a multifactorial etiology. It is critical to identify modifiable risk factors to mitigate the risk. One key area of interest is the role of intraoperative hypotension, which remains relatively unexplored in liver transplant cohorts. Methods: This was a retrospective observational cohort study of 1292 adult patients who underwent LT (between 2009 and 2019). Multivariable logistic regression analysis was used to explore the association between intraoperative hypotension, quantified by time duration (in min) under various mean arterial pressure (MAP) thresholds, and the primary outcome of early postoperative AKI according to the KDIGO criteria. Results: AKI occurred in 40% of patients and was independently associated with greater than 20 min spent below MAP thresholds of 55 mm Hg (adjusted OR = 1.866; 95% CI = 1.037–3.44; P = 0.041) and 50 mm Hg (adjusted OR = 1.801; 95% CI = 1.087–2.992; P = 0.023). Further sensitivity analyses demonstrated that the association between intraoperative hypotension and postoperative AKI was accentuated after restricting the analysis to patients with a normal preoperative renal function. Conclusions: Prolonged (>20 min) intraoperative hypotension (below a MAP of 55 mm Hg) was independently associated with AKI following LT, after adjusting for several known confounders.