Predictors and clinical outcomes of acute kidney injury after thoracic surgery: a retrospective cohort study.

BACKGROUND

Acute kidney injury (AKI), defined as a rapid decline of renal function, is a frequent complication observed after major surgical procedures. In patients undergoing thoracic surgery, the reported incidence of AKI ranges from 5% to 15%. The development of AKI is associated with an elevated risk of postoperative complications, including the need for reintubation, longer hospital admissions, and higher mortality rates. During one-lung ventilation (OLV), intraoperative hypoxemia and hypercarbia, along with systemic inflammation induced by alveolar over-distension, can contribute to decreased renal perfusion, which may ultimately result in AKI. This study aims to determine the incidence, identify predictive factors, and evaluate the clinical outcomes associated with AKI following thoracic surgery.

METHODS

In retrospective cohort study, all consecutive patients aged 18 years and over undergoing non-cardiac thoracic surgery at a tertiary university hospital between 2012 and 2021 were enrolled. AKI was diagnosed by Kidney Disease Improving Global Outcomes (KDIGO)-2012. The univariable and multivariable logistic regression were analyzed and presented as odds ratio (OR) and 95% confidence interval (CI). A Kaplan-Meier curve and log-rank test were used for comparison of hospital mortality between patients with or without AKI.

RESULTS

The incidence of AKI was 23.9% (318 of 1,329 patients), with cases classified as stage I (184, 13.8%), stage II (115, 8.7%), or stage III (19, 1.4%) according to the KDIGO criteria. In the multivariable logistic regression analysis, age ≥70 years (OR, 1.74; 95% CI: 1.21-2.50, P=0.003), body mass index (BMI) >25 kg/m2 (OR, 2.39; 95% CI: 1.73-3.36; P<0.001), baseline estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 (OR, 1.89; 95% CI: 1.28-2.79; P=0.001), open thoracotomy (OR, 1.54; 95% CI: 1.15-2.07; P=0.003), intraoperative hydroxyethyl starch administration >1,000 mL (OR, 3.18; 95% CI: 1.19-8.54; P=0.02) and intraoperative urine output <0.5 mL/kg/h (OR, 1.80; 95% CI: 1.30-2.52; P=0.001) were significantly associated with the development of AKI. Patients who developed AKI had a significantly higher incidence of postoperative delirium (15.5%), requirement for continuous renal replacement therapy (CRRT) (3.5%), prolonged intensive care unit (ICU) stay [0 (0-2) vs. 0 (0-1) days, P=0.001], longer hospital stays {14.5 [9-24] vs. 9 [6-18] days, P=0.005}, and an increased mortality rate (10.1% vs. 5%, P=0.001) compared to those without AKI. Patients with stage III AKI had a significantly higher 30-day mortality rate compared to other stages (P<0.001).

CONCLUSIONS

The findings of this study highlight important predictors for AKI in patients undergoing thoracic surgery. Recognizing these predictors early may support timely interventions and the development of strategies aimed at reducing the likelihood of AKI, thereby promoting better postoperative recovery.