Low Mean Arterial Blood Pressure is Independently Associated with Postoperative Acute Kidney Injury After Living Donor Liver Transplantation: A Propensity Score Weighing Analysis

BACKGROUND: As end-stage liver disease progresses, renal blood flow linearly correlates with mean arterial blood pressure (MBP) due to impaired autoregulation. We investigated whether the lower degree of postoperative MBP would predict the occurrence of postoperative acute kidney injury (AKI) after liver transplantation. MATERIAL/METHODS: This retrospective study enrolled 1,136 recipients with normal preoperative kidney function. Patients were categorized into two groups according to the averaged postoperative MBP: <90 mmHg (MBP(below90)) and ≥90 mmHg (MBP(over90)). The primary endpoint was occurrence of postoperative AKI, defined by the creatinine criteria of the Kidney Disease Improving Global Outcomes. The logistic regression model with inverse probability treatment weighting (IPTW) of propensity score was used to compare the risk of postoperative AKI between two groups. RESULTS: MBP(below90) group (83.0±5.1 mmHg) showed higher prevalence and risk of postoperative AKI (74.2% versus 62.6%, p<0.001; IPTW-OR 1.34 [1.12–1.61], p=0.001) compared with MBP(over90) group (97.3±5.2 mmHg). When stratified by quartiles of baseline cystatin C glomerular filtration ratio (GFR), the association between MBP(below90) and postoperative AKI remained significant only with the lowest quartile (cystatin C GFR ≤85 mL/min/1.73 m(2); IPTW-OR 2.24 [1.53–3.28], p<0.001), but not with 2(nd)–4(th) quartiles. CONCLUSIONS: Our results suggest that maintaining supranormal MBP over 90 mmHg may be beneficial to reduce the risk of post-LT AKI, especially for liver transplant recipients with cystatin C GFR ≤85 mL/min/1.73 m(2).