[Impact of mean perfusion pressure on the risk of sepsis-associated acute kidney injury]

Abstract

Objective: To investigate the relationship between mean perfusion pressure (MPP) and the risk of sepsis-associated acute kidney injury (SA-AKI) and its prognosis, and to determine the optimal cut-off value of MPP for predicting SA-AKI.

Methods: A retrospective cohort study was conducted. The clinical data of adult patients with sepsis were collected from the Medical Information Mart for Intensive Care-IV 2.2 (MIMIC-IV 2.2) database. The patients were divided into two groups based on the occurrence of SA-AKI. Baseline characteristics, vital signs, comorbidities, laboratory indicators within 24 hours of intensive care unit (ICU) admission, and clinical outcome indicators were collected. Mean MPP was calculated using the average values of mean arterial pressure (MAP) and central venous pressure (CVP), MPP = MAP-CVP. Cox regression models were constructed, relevant confounding factors were adjusted, and multivariate Logistic regression analysis was used to investigate the associations between MPP and the risk of SA-AKI as well as ICU death. The predictive value of MPP for SA-AKI was evaluated using receiver operator characteristic curve (ROC curve) analysis, and the optimal cut-off value was determined.

Results: A total of 6 009 patients were ultimately enrolled in the analysis. Among them, SA-AKI occurred in 4 755 patients (79.13%), while 1 254 patients (20.87%) did not develop SA-AKI. Compared with the non-SA-AKI group, the MPP in the SA-AKI group was significantly lowered [mmHg (1 mmHg≈0.133 kPa): 62.00 (57.00, 68.00) vs. 65.00 (60.00, 70.00), P < 0.01], and the ICU mortality was significantly increased [11.82% (562/4 755) vs. 1.59% (20/1 254), P < 0.01]. Three Cox regression models were constructed: model 1 was unadjusted; model 2 was adjusted for gender, age, height, weight and race; model 3 was adjusted for gender, age, height, weight, race, heart rate, respiratory rate, body temperature, hemoglobin, platelet count, white blood cell count, anion gap, HCO₃^-, blood urea nitrogen, serum creatinine, Cl^-, Na⁺, K⁺, fibrinogen, international normalized ratio, blood lactic acid, pH value, arterial partial pressure of oxygen, arterial partial pressure of carbon dioxide, sequential organ failure assessment score, Charlson comorbidity index score, use of vasopressors, mechanical ventilation, and urine output. Multivariate Logistic regression analysis showed that when MPP was treated as a continuous variable, there was a negative correlation between MPP and the risk of SA-AKI in model 1 and model 2 [model 1: odds ratio (OR) = 0.967, 95% confidence interval (95%CI) was 0.961-0.974, P < 0.001; model 2: OR = 0.981, 95%CI was 0.974-0.988, P < 0.001], and also a negative correlation between MPP and the risk of ICU death (model 1: OR = 0.955, 95%CI was 0.945-0.965, P < 0.001; model 2: OR = 0.956, 95%CI was 0.946-0.966, P < 0.001). However, in model 3, there was no significant correlation between MPP and either SA-AKI risk or ICU death risk. when MPP was used as a multi-categorical variable, in model 1 and model 2, referring to MPP ≤ 58 mmHg, when 59 mmHg ≤ MPP ≤ 68 mmHg, as MPP increased, the risk of SA-AKI progressively decreased (OR value was 0.411-0.638, all P < 0.001), and the risk of ICU death also gradually decreased (OR value was 0.334-0.477, all P < 0.001). ROC curve showed that MPP had a certain predictive value for SA-AKI occurrence [area under the ROC curve (AUC) = 0.598, 95%CI was 0.404-0.746], and the optimal cut-off value was 60.5 mmHg.

Conclusion: MPP was significantly associated with the risk of SA-AKI, with an optimal cut-off value of 60.5 mmHg, and also demonstrated a significant correlation with the risk of ICU death.