Background: Hyperglycemia is common following cardiopulmonary bypass (CPB) surgery and is associated with poor outcomes, often attributed to hyperinsulinemia and an acquired state of insulin resistance. This study examined the underpinnings of hyperglycemia and the effects of nutrition on the association with inflammation and clinical outcomes.
Methods: This prospective, observational cohort study enrolled consecutive children (<18 years) undergoing CPB. Serial measurements of inflammatory cytokines, glucose, insulin, and nutrition delivery were obtained. Glucose-insulin ratio (G:I) was calculated for each time point as a measure of insulin resistance (lower G:I reflects higher resistance). Clinical outcomes were recorded using a composite morbidity score.
Results: The 200 subjects studied were predominantly females (58%) undergoing biventricular repair (85%) at a median (interquartile range) age of 0.58 years (0.28, 3.4) and weight of 7.0 kg (3.1, 59.5). Hyperglycemia was common (49% of patients), coinciding with peak cytokine concentrations. Insulin levels were highest and G:I lowest immediately following separation from CPB but had no consistent relationship with cytokines. The morbidity outcome was reached by 23% of patients, with increased odds associated with higher interleukin (IL)6 and IL8 levels but not by glucose, insulin, or G:I. Providing higher feeding volumes attenuated this association between inflammation and morbidity. Higher feeds were not associated with G:I but appeared to decrease the strength of the relationship between cytokines and glycemic indices.
Conclusion: Postoperative morbidity is independently associated with increased inflammation but not with hyperglycemia or markers of insulin resistance. Higher feeding volume may modify these relationships and have a protective role.
Keywords: cardiopulmonary bypass; children; enteral nutrition; hyperglycemia; inflammation; insulin resistance.
© 2019 American Society for Parenteral and Enteral Nutrition.