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Association Between Hyperoxemia and Increased Cell-Free Plasma Hemoglobin During Cardiopulmonary Bypass in Infants
Catherine Gretchen1,2, Hϋlya Bayir1,3,4,5, Patrick M Kochanek1,3,5
1Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA.
Insights
Pediatric cardiopulmonary bypass can cause severe hemolysis. Younger age and high oxygen levels combined with longer bypass duration are key risk factors. Modifying oxygen exposure may reduce hemolysis risk.
Area of Science:
- Pediatric critical care medicine
- Cardiovascular surgery
- Hemolysis research
Background:
- Cardiopulmonary bypass (CPB) is essential for pediatric cardiac surgery.
- Hemolysis, or red blood cell destruction, is a known complication of CPB.
- Identifying risk factors for severe hemolysis is crucial for improving patient outcomes.
Purpose of the Study:
- To identify risk factors for severe hemolysis in pediatric patients undergoing CPB.
- To investigate the association between supraphysiologic oxygen levels, CPB duration, and hemolysis.
Main Methods:
- Prospective observational study of 100 pediatric patients undergoing CPB.
- Measured cell-free plasma hemoglobin and haptoglobin levels at multiple time points.
- Collected arterial blood gas data and patient demographics.
Main Results:
- Severe hemolysis (n=44) was associated with younger age and higher mean Pao2 x CPB duration.
- Plasma hemoglobin peaked at the end of CPB; haptoglobin levels decreased throughout.
- Severe hemolysis correlated with longer hospital/ICU stays and acute kidney injury.
Conclusions:
- Younger age and combined exposure to high oxygen and prolonged CPB duration are risk factors for pediatric hemolysis.
- Oxygen delivery during CPB is a modifiable factor requiring further investigation.
- Understanding these risks can guide strategies to mitigate hemolysis during CPB.
Objectives:
To determine potential risk factors for severe hemolysis during pediatric cardiopulmonary bypass and examine whether supraphysiologic levels of oxygen and cardiopulmonary bypass duration are associated with hemolysis.
Design:
Prospective observational study.
Setting:
Cardiac ICU in a university-affiliated children's hospital.
Patients:
Greater than 1 month to less than 18 years old patients undergoing cardiopulmonary bypass for cardiac surgery.
Interventions:
None.
Measurements And Main Results:
Plasma samples from 100 patients to assess cell-free plasma hemoglobin levels were obtained at start cardiopulmonary bypass, at the end of cardiopulmonary bypass, and 2 and 24 hours after reperfusion. Arterial blood gas samples were obtained before and every 30 minutes during cardiopulmonary bypass. Patient demographics and laboratory data were collected from the electronic medical record. Plasma hemoglobin levels peaked at the end of cardiopulmonary bypass and haptoglobin levels continued to fall throughout all time points. There were 44 patients with severe hemolysis (change in cell-free plasma hemoglobin > 50 mg/dL). Younger age (odds ratio/sd 0.45 [95% CI, 0.25-0.81]) and higher mean Pao2 × cardiopulmonary bypass duration (31.11 [1.46-664.64]) were identified as risk factors for severe hemolysis in multivariable analysis. Severe hemolysis was associated with longer hospital and ICU lengths of stay as well as acute kidney injury.
Conclusions:
We observed younger age and the exposure to both oxygen and duration of cardiopulmonary bypass as risk factors for hemolysis. Oxygen delivery through the cardiopulmonary bypass circuit is an easily modifiable risk factor. Its role in the production of reactive oxygen species that could alter the erythrocyte membrane deserves further examination in larger prospective studies.
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