Systemic inflammation and acute kidney injury after colorectal surgery.

Background: In this retrospective review, the relative importance of systemic inflammation among other causes of acute kidney injury (AKI) was investigated in 1224 consecutive colorectal surgery patients. A potential benefit from reducing excessive postoperative inflammation on AKI might then be estimated.

Methods: AKI was determined using the Kidney Disease Improving Global Outcomes (KDIGO) criteria. The entire population (mixed group), composed of patients with or without sepsis, and a subpopulation of patients without sepsis (aseptic group) were examined. Markers indicative of inflammation were procedure duration, the first postoperative white blood cell (POD # 1 WBC) for the mixed population, and the neutrophil-to-lymphocyte ratio (POD #1 NLR) for the aseptic population. Multivariable logistic regression was then performed using significant (P < 0.05) predictors. The importance of inflammation among independent predictors of AKI and AKI-related complications was then assessed.

Results: AKI occurred in 24.6% of the total population. For the mixed population, there was a link between inflammation (POD # 1 WBC) and AKI (P = 0.0001), on univariate regression. Medications with anti-inflammatory properties reduced AKI: ketorolac (P = 0.047) and steroids (P = 0.038). Similarly, in an aseptic population, inflammation (POD # 1 NLR) contributed significantly to AKI (P = 0.000). On multivariable analysis for the mixed and aseptic population, the POD #1 WBC and the POD #1 NLR were independently associated with AKI (P = 0.000, P = 0.022), as was procedure duration (P < 0.0001, P < 0.0001). Inflammation-related parameters were the most significant contributors to AKI. AKI correlated with complications: postoperative infections (P = 0.016), chronic renal insufficiency (CRI, P < 0.0001), non-infectious complications (P = 0.010), 30-day readmissions (P = 0.001), and length of stay (LOS, P < 0.0001). Inflammation, in patients with or without sepsis, was similarly a predictor of complications: postoperative infections (P = 0.002, P = 0.008), in-hospital complications (P = 0.000, P = 0.002), 30-day readmissions (P = 0.012, P = 0.371), and LOS (P < 0.0001, P = 0.006), respectively.

Conclusions: Systemic inflammation is an important cause of AKI. Limiting early postsurgical inflammation has the potential to improve postoperative outcomes.