345 Comparison of Cerebral Tissue Oxygenation Index and Cardiac Output in Infants with Birth Weight Less Than 1250 Grams

Abstract

Background and aims: (1) To correlate cerebral tissue oxygenation index (cTOI) and cardiac output measurements in infants with birth weight less than 1250 g during first 48 hours of life. (2) To correlate these measurements with clinical parameters. Methods: A prospective observational study. Newborns with birth weight < 1250g were eligible for enrolment. Superior vena cava (SVC) flow, right and left ventricular outputs were measured. Patent ductus arteriosus was assessed and cTOI was measured. All measurements were done at 6, 12, 24 and 48 hours of age. Various clinical parameters (including mean blood pressure, mean airway pressure, pH, pO2, pCO2, O2 saturations) were also recorded.Results: 10 neonates were enrolled following parental consent. The mean birth weight was 767 g (SD±184), mean gestational age was 25.3 weeks (SD±1.4). Mean SVC flow at 6 hours of age was 59.6 ml/kg/min and increased to 76.2 ml/kg/min at 48 hours of age. Mean cTOI was 64.9% at 6 hours of age, 63.3% at 12 hours of age, 67.5% at 24 hours of age and 67.7% at 48 hours of age. Mean cerebral fractional tissue oxygen extraction (cFTOE) did not change significantly and was 0.28, 0.31, 0.28 and 0.27 at 6, 12, 24 and 48 hours respectively. There was no significant correlation between SVC flow and cTOI.Conclusion: Superior vena cava flow increased during first 48 hours of life. There was a slight increase in cTOI and no change in cFTOE. This may reflect increased cerebral metabolism during the first 48 hrs.