Hyperglycaemia is negatively associated with systemic and cerebral oxygen transport in neonates after the Norwood procedure

Abstract

Hyperglycaemia has been identified as a risk factor for adverse outcomes in critically ill patients, including those who have undergone cardiopulmonary bypass. Tight glucose control with insulin therapy has been shown to improve outcomes, but is not common practice for children following cardiopulmonary bypass. We examined the relationship between blood glucose level and systemic and cerebral oxygen transport in a uniform group of neonates after the Norwood procedure. Systemic oxygen consumption was measured using respiratory mass spectrometry in 17 neonates for 72 hours postoperatively. Cardiac output, systemic and total pulmonary vascular resistances - including the Blalock-Taussig shunt, systemic oxygen delivery and oxygen extraction ratio, as well as arterial lactate and glucose, were measured at 2- to 4-hour intervals. Cerebral oxygen saturation was measured by near-infrared spectroscopy. Blood glucose levels ranged from 2.8 to 24.6 millimoles per litre. Elevated glucose level showed a significant negative correlation with cardiac output (p = 0.02) and cerebral oxygen saturation (p = 0.03), and a positive correlation with oxygen extraction ratio (p = 0.03). It tended to correlate positively with systemic vascular resistance (p = 0.09) and negatively with oxygen delivery (p = 0.09), but did not correlate with oxygen consumption (p = 0.13). Hyperglycaemia is negatively associated with systemic haemodynamics, oxygen transport, and cerebral oxygenation status in neonates after the Norwood procedure. Further study is warranted to examine tight glucose control with insulin therapy on postoperative systemic and cerebral oxygen transport and functional outcomes in neonates after cardiopulmonary bypass.