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Total and free cortisol responses and their relation to outcomes after cardiopulmonary bypass in infants
Eric L Wald1, Carl L Backer2, Joseph A Dearani3
1Divisions of Critical Care and Cardiology, Department of Pediatrics, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Insights
Infants undergoing cardiac surgery with cardiopulmonary bypass show a significant decline in HPA axis function. Subnormal cortisol responses post-surgery correlate with increased fluid needs and longer hospital stays.
Area of Science:
- Pediatric Cardiology
- Endocrinology
- Critical Care Medicine
Background:
- Hypothalamic-pituitary-adrenal (HPA) axis dysfunction may contribute to hemodynamic instability in infants post-cardiopulmonary bypass (CPB).
- This study investigates the HPA axis response in infants undergoing CPB for congenital cardiac surgery.
Purpose of the Study:
- To characterize the full spectrum of the HPA axis response in infants before and after CPB.
- To assess the relationship between HPA axis function and clinical outcomes, including fluid requirements, chest tube output, and length of stay.
Main Methods:
- Eighty-four infants received dexamethasone before CPB.
- Total cortisol (TC), free cortisol (FC), ACTH, and CBG were measured at three time points: pre-CPB, ICU arrival, and 24 hours post-surgery.
- Adrenal responsiveness was evaluated using an ACTH stimulation test at each time point.
Main Results:
- Cortisol and ACTH levels significantly decreased 24 hours post-surgery.
- No significant association was found between preoperative free cortisol and clinical outcomes.
- Subnormal total cortisol response to ACTH stimulation postoperatively was linked to increased fluid requirements, chest tube output, and longer length of stay.
Conclusions:
- The HPA axis function significantly declines in the 24 hours following CPB in infants.
- Postoperative subnormal cortisol response to stimulation is associated with adverse clinical outcomes, including increased fluid resuscitation and longer hospital stays.
Background:
Hypothalamic-pituitary-adrenal (HPA) axis dysfunction may be partially responsible for the hemodynamic instability experienced by infants after cardiopulmonary bypass (CPB). We report the full spectrum of the HPA response surrounding CPB for infant congenital cardiac surgery.
Methods:
We enrolled 84 infants who received 1 mg/kg of dexamethasone before initiation of CPB. Total cortisol (TC), free cortisol (FC), adrenocorticotropic hormone (ACTH), and corticosteroid-binding globulin (CBG) were measured at 3 time points: immediately before CPB (TP1), on intensive care unit arrival (TP2), and at 24 hours after surgery (TP3). A 1-μg ACTH stimulation test was performed at each time point to evaluate adrenal responsiveness.
Results:
Sixty-eight infants completed all study procedures. Levels of TC, FC, CBG, and ACTH decreased significantly between the preoperative and 24-hour postoperative measurements. There were no significant associations between preoperative FC responses and clinical outcomes after adjusting for weight and Risk-Adjusted Scores for Congenital Heart Surgery. Infants with subnormal TC responses to ACTH stimulation (<9 μg/dL) at TP2 had greater fluid requirements (P < .001) and greater chest tube output (P < .001) during the first 24 hours, as well as longer length of stay (LOS) (P = .007). Except for LOS, these differences persisted for infants with subnormal stimulation tests at TP3.
Conclusions:
We observed a significant decline in all aspects of the HPA axis throughout the first 24 hours after infant CPB. TC and FC levels were not associated with clinical outcomes. Subnormal (Δ <9 μg/dL) TC response to cosyntropin stimulation during the postoperative period was associated with increased fluid resuscitation and greater LOS.
