Haematocrit differences modify the association of cardiopulmonary bypass reoxygenation with acute kidney injury after paediatric Tetralogy of Fallot repair

Abstract

Background: Little is known regarding the potential impact of haematocrit differences in the association between cardiopulmonary bypass reoxygenation and acute kidney injury following Tetralogy of Fallot repair. Methods: We investigated the association of perfusate oxygenation during aortic occlusion associated with acute kidney injury between 204 normal and 248 higher haematocrit children with Tetralogy of Fallot, aged 1 month-18 years, who were surgically repaired in 2012-2018. Normal and higher haematocrit children were defined as having a preoperative haematocrit within and above age- and sex-specific reference intervals, respectively. Acute kidney injury was determined as a binary variable according to the Kidney Disease Improving Global Outcomes criteria. Results: After adjusting for baseline and clinical covariates, a significant interaction between the haematocrit and continuous perfusate oxygenation on acute kidney injury was found (pinteraction = 0.049): a higher perfusate oxygenation was associated with a greater acute kidney injury risk among higher haematocrit children (adjusted odds ratio = 1.50, 95% confidence interval = [1.02, 2.22] per SD, p = 0.038) but not among normal haematocrit children (adjusted odds ratio = 0.91, 95% confidence interval = [0.51, 1.63] per SD, p = 0.73). After a similar adjustment, there was a marginal interaction between tertiles of perfusate oxygenation and haematocrit on acute kidney injury (pinteraction = 0.09): the middle and top tertiles of perfusate oxygenation were associated with a trend towards increased acute kidney injury risks among higher haematocrit children (adjusted odds ratio = 1.69, 95% confidence interval = [0.61, 4.66]; adjusted odds ratio = 2.25, 95% confidence interval = [0.84, 5.99], respectively) but not among normal haematocrit children (adjusted odds ratio = 1.16, 95% confidence interval = [0.46, 2.94]; adjusted odds ratio = 0.45, 95% confidence interval = [0.15, 1.36], respectively) compared with the bottom tertile. Conclusion: Preoperative haematocrit differences significantly modify the association of perfusate oxygenation with acute kidney injury, highlighting differential control of reoxygenation for different haematocrit children with Tetralogy of Fallot in the management of cardiopulmonary bypass.

Commentary: Is perfusate arterial oxygen tension the best barometer of inflammation following cardiopulmonary bypass for congenital heart surgery?

“…The range of PpaO 2 , to which patients of both groups were exposed, was 250 to 350 mm Hg, a number that other investigators, 6 including previous work from the same group, 7 would define as hyperoxia. Ultimately, using complex statistics, the authors found that a PpaO 2 threshold of >310 mm Hg for low-altitude patients and >350 mm Hg for high-altitude patients was associated with a high probability of development of severe SIRS.…”

Effect of cardiopulmonary bypass reoxygenation on myocardial dysfunction following pediatric tetralogy of Fallot repair

“…Pump flow was settled at approximately 2.8 L/min/m 2 at the outset of CPB and subsequently adjusted according to patient's core temperature (usually a 20% decrease for core temperatures between 30 and 34 °C and an additional 10% decrease for core temperatures < 30 °C). The hemodilution level was decreased to 25-30% during hypothermic CPB according to the routine protocol of our institution [11].…”

Relation or Influence of RVOTO in the Inflammatory Response to Reoxygenation in Patients with Tetralogy of Fallot

“…CPB is primed with Plasma-Lyte A, followed by the addition of packed red blood cells and fresh frozen plasma to achieve the desired hematocrit of 25% on CPB. At initiation of CPB, flow rates are maintained at approximately 150-200 mL/Kg/min and 100-150 mL/Kg/min for patients weighted <10 kg and >10 kg, respectively, subsequently adjusted according to the patient's core temperature (usually a 20% decrease for core temperatures between 30°C and 34°C and an additional 10% decrease for core temperatures <30°C) following our institute protocol [11]. All patients received standardized a-stat CPB management and standardized critical care management according to our institute.…”