Impact of Different Cardiopulmonary Bypass Strategies on Renal Injury after Pediatric Heart Surgery

Ann Thorac Surg. 2020 Jun 27. Online ahead of print

In this contemporary comparative study, higher flow rates and higher hematocrit during cardiopulmonary bypass were associated with better preservation of renal function.

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Background

To compare the incidence and severity of acute kidney injury (AKI) following open heart surgery in neonates and infants for two different cardiopulmonary bypass (CPB) strategies.

Methods

151 infants undergoing cardiac surgery were prospectively enrolled between June 2017 and June 2018 at 2 centers, one using conventional CPB (2.4 L/min/m2, 150 mL/kg/min) with reduction of flow rates with moderate hypothermia and with a targeted hematocrit >25% (Center 1, n=91) and the other using higher bypass flow rates (175-200 mL/kg/min) and higher minimum hematocrit (>32%) CPB (Center 2, n=60). The primary endpoint was the incidence of post-operative AKI as defined by Acute Kidney Injury Network criteria and risk factors associated with AKI.

Results

Pre-operative characteristics and complexity of surgery were comparable between centers. The overall incidence of early post-operative AKI was 10.6% (16/151), with 15.4% (14/91) in Center 1 and 3.3% (2/60) in Center 2 (p = 0.02). Mean lowest flow rates on CPB were 78 mL/kg/min vs 118 mL/kg/min and mean highest hematocrit on separation from CPB were 33% vs 43% at Center 1 and 2 respectively (p<0.001). Center 1 used less PRBCs but more FFP than Center 2 (p=0.001). By multivariate analysis, only lower flows on CPB (78 vs. 96 mL/kg/min, p=0.043) and lower hematocrit at the end of CPB (33% vs. 37%, p=0.007) were associated with AKI.

Conclusions

In this contemporary comparative study, higher flow rates and higher hematocrit during cardiopulmonary bypass were associated with better preservation of renal function.