Hyperthermic perfusion during cardiopulmonary bypass and postoperative temperature are independent predictors of acute kidney injury following cardiac surgery

Abstract

Acute kidney injury (AKI) following cardiopulmonary bypass (CPB) is associated with increased mortality, requirement for dialysis, and longer intensive care unit (ICU) and hospital length of stay. Rewarming during CPB and poor oxygen delivery have been associated with AKI; however, the role of temperature management on AKI has not been clearly defined. This study aims to evaluate the role of hyperthermia during CPB and the temperature upon admission to the ICU on AKI following cardiac surgery, using the RIFLE (renal Risk, Injury, Failure, Loss of renal function and End-stage renal disease) criteria. To determine whether CPB hyperthermia (measured as the cumulative time the arterial outlet temperature >37°C) and ICU admission temperature were independent risk factors for AKI, data from 1393 consecutive adult patients undergoing isolated on-pump coronary artery bypass graft (CABG), valve repair and/or replacement and valve/CABG procedures was analysed using a logistic multivariate model. After testing for interaction, we incorporated covariates having a p-value <0.1. AKI was defined according to the RIFLE criteria as an increase in serum creatinine >50% from baseline to peak value postoperatively. Overall, 12.3% of patients developed AKI with a 4.5-fold increase in in-hospital mortality. Variables found to be independent predictors of AKI included CPB hyperthermia (Odds ratio [OR] 1.03 per minute increase [95% confidence interval (CI) 1.01-1.05]; p = 0.01), ICU admission temperature ([OR] 1.44 per degree increase [(CI) 1.13-1.85]; p<0.001), minimum CPB haemoglobin ([OR] 0.83 per g/dL increase [(CI) 0.71-0.97]; p = 0.02), use of intra-aortic balloon pump ([OR] 2.69 [(CI) 1.24-5.82]; p = 0.01) and ICU readmission ([OR] 3.13 [(CI) 1.73-5.64]; p<0.001). Avoiding arterial outlet hyperthermia may help decrease AKI following cardiac surgery using CPB. Both intraoperative and postoperative temperature management strategies should be the focus of future randomised studies to determine optimal interventions.

The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass—Temperature Management During Cardiopulmonary Bypass

“…This finding was supported by Newland and colleagues [29] (2013), who reported an arterial outlet temperature higher than 37 C is an independent predictor of acute kidney injury.…”

“…Groom and coworkers [28] (2004) reported an association with hyperthermia (defined as a peak core temperature >37.9 C) and an increased rate of mediastinitis. Newland and colleagues [29] reported in 2013 that an arterial outlet temperature exceeding 37 C during CPB is an independent predictor of acute kidney injury.…”

Pediatric acute kidney injury: Appraisal of predictors and prognostic indicators

“…However, while some researchers have noted that higher MAP and systemic oxygen delivery were renoprotective in early AKI and precluded disease progression [33], others have reported that high MAP did not reduce the risk of post-operative AKI during normothermic CPB, or change the duration of hospitalization and mortality rate [34]. In one study, critically ill patients with early AKI and DO2I > 450 mL/min/m 2 within the first 12 h of diagnosing the early stage of the disease had a significantly lower susceptibility of progressing to late disease in comparison to patients with DO2I < 450 mL/min/m Interestingly, the findings of another study showed that hyperthermic CPB was an independent predictor of AKI, as avoiding arterial outlet hyperthermia may help to reduce AKI risk [35]. Furthermore, few evidence-based studies indicated that the avoidance of hypotension in stage I AKI, by for instance maintaining MAP at less than 70-75 mmHg, may reduce the incidence of stage III AKI [36,37].…”

Acute Kidney Injury in the Surgical Patient

“…Rewarming after CPB and hyperthermic perfusion during CPB are novel risk factors for AKI after cardiac surgery [66, 67]. A recent systematic review of perioperative interventions aimed to optimize global blood flow showed no difference in mortality, but the rates of renal failure (relative risk (RR) 0.71, 95% confidence interval (CI) 0.57 to 0.90) were reduced [68].…”