Nephrocheck Measurements at Intensive Care Unit Admission and 24 Hours after Cardiac Surgery Are Associated with the Incidence of Acute Kidney Injury: A Prospective Cohort Study

Objectives: Acute kidney injury (AKI) is a common postoperative complication after cardiac surgery (CS) with a high impact on long term mortality and morbidity. Identification of patients at risk for AKI and early diagnosis of AKI is crucial to adjust medical therapy. Nephrocheck (NC) measures markers of tubular stress, which occurs prior to tubular damage, and it has been introduced for early detection of AKI. Yet, it is unknown at which time point NC measurement should be performed to predict AKI in patients undergoing cardiac surgery. In the current study, we investigated the association of NC measurements at different time points with the incidence of AKI in patients undergoing elective cardiac surgery.

Methods: In this prospective cohort study, we enrolled 150 patients undergoing CS including CPB (CABG, Valve, thoracic aorta and combined procedures). Blood and urine samples were collected at introduction of anesthesia (baseline), ICU-admission, 24 and 48 hours post-surgery. AKI within 48h was defined as SCr rise >0.3 mg/dl according to KDIGO. NC was measured in urine samples at baseline and at ICU-admission by study personnel on-site, results were not shown to the treating physicians.

Results: Patients were on average 67yrs old with 42% being female. Median EUROSCORE II was 1.75. Subjects with NC values of >0.3 at post-operative ICU-admission were less likely to having received CABG surgery (54.4 vs. 22.7%; p = 0.008), but time on CPB was longer (1:59h vs. 1:34h, p = 0.01), and patients were more likely to have preoperative pacemaker treatment (20.0 vs. 1.3%, p = 0.008) and tended to have heart failure (54.1 vs. 30.0%; p = 0.06).

A total of 34 (22.7%) of patients experienced AKI within 48h, with a higher incidence in those with high NC values at ICU admission (57.1 vs. 10.1%, p < 0.001), which were also more severe stages of AKI (stage 2: 33.3 vs. 0%, p = 0.002). In logistic regression modelling, only NC values at ICU admission were independently associated with the occurrence of AKI (OR 11.83 [3.82; 36.7; p < 0.001, C-statistic = 0.74) after adjustment for EUROSCORE 2 and CPB-time. NC measurements at baseline were not associated with AKI, neither univariate (p = 0.5), nor in multivariate modelling (p = 0.9).

Conclusion: We found that in patients undergoing CS, NC measurements immediately after surgery were highly predictive for the incidence of AKI, independent from patient characteristics, preoperative NC values and intraoperative parameters.

 

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No conflict of interest has been declared by the author(s).