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Impact of Pre-Operative Acute Kidney Injury and Post-Operative Non-Recovery of Renal Function by Day 7 In Children with Congenital Heart Disease and Outcomes

Saturday, October 20, 2012: 11:45 AM
Room 275-277 (Morial Convention Center)
Kyle J. Bielefeld, M.D., Pediatric Cardiology, UAMS, Little Rock, AR, Adnan Bhutta, Cardiology, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR, Jeffrey Gossett, M.S., Pediatric Cardiology, University of Arkansas for Medical Sciences, Little Rock, AR and Parthak Prodhan, Pediatrics, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR

Purpose: Acute kidney injury (AKI) is associated with increased mortality and morbidity in children and adult patients cared for in ICUs. Cardiac surgery requiring cardiopulmonary bypass is known to be associated with AKI in children. We hypothesize that (a) a significant proportion of children with cardiac disease have AKI pre-operatively, (b) pre-operative AKI is associated with increased mortality, (c) failure to recover renal function by post-operative day 7 after cardiopulmonary bypass in children is also associated with increased morbidity and mortality as there is currently no available data in the literature.

Methods: This retrospective cohort study included consecutive children < 2 years of age who were undergoing their first cardiac surgical procedure with cardiopulmonary bypass at Arkansas Children’s Hospital from January2003 to June 2005.  We excluded children less than 2 years of age who were undergoing procedures without cardiopulmonary bypass or those undergoing orthotopic heart transplantation, inasmuch as heart transplantation is not included the Risk Adjusted classification for Congenital Heart Surgery (RACHS-1) used.  Estimated glomerular filtration rate (eGFR) was calculated using the modified Schwartz formula and compared to normal eGFR for age. eGFR less than the predicted 3rdpercentile was used as a baseline for assigning pRIFLE scores. Univariate and multivariate statistics were used to investigate association of AKI with outcomes. A p value of < 0.05 was considered statistically significant.

Results: Of the 280 patients identified, 164 (61%) had pre-operative AKI.  A total of 76 subjects did not recover eGFR ≥75% of the predicted 3rdpercentile by post-operative day 7.  The group of patients who failed to recover: were younger at the time of surgery, had lower weight at the time of surgery, had greater need for dialysis, saw a larger drop in post-operative eGFR, had a longer ICU stay and total hospital stay, longer time of ventilation, and increased mortality (all p<0.001).  For pre-operative AKI, a logistic regression to predict death using indicators for age<30 days, lymphopenia, RACHS score (1:1-2, 3-4, 5-6) , and the percentage difference between eGFR at baseline and the normal eGFR for age indicated that pre-operative AKI was not associated with increased in-hospital mortality (p value=0.07). Only pre-operative absolute lymphocyte count less than 3000 (O.R.=6.84, 95% CI-1.34 to 34.86) was significantly associated with mortality.

Conclusions: Pre-operative AKI was present in 61% of patients but was not associated with increased risk of in-hospital mortality.  However, failure to recover eGFR ≥75% of the predicted 3rd percentile by post-operative day 7 after cardiopulmonary bypass was associated with increased risk of mortality and morbidity.