Effect of a change in global metabolic rate on peripheral oxygen consumption in neonates

Aim: To evaluate the effect of an induced change in global metabolic rate on peripheral oxygen consumption (VO2) in healthy full term neonates. Subjects and methods: Twenty four healthy full term neonates were studied. Peripheral VO2 was measured by near infrared spectroscopy (NIRS) using arterial acclusion and measurement of the oxyhaemoglobin (HbO2) decrement slope. Global VO2 was measured by open circuit calorimetry. Global and peripheral VO2 were measured in each neonate before and after a routine bath. Abdominal and forearm skin temperatures were also recorded. Results: Nineteen neonates completed the study. Global VO2 increased by 30.7% (p = 0.001), and peripheral VO2 by 23.1% (p = 0.001). A correlation between the fractional changes in global and peripheral VO2 was apparent (r = 0.76, p = 0.001). Abdominal skin temperature decreased by 0.8°C (p = 0.001), and forearm skin temperature by 0.6°C (p = 0.04). Conclusions: Measurement of peripheral VO2 using NIRS with arterial occlusion is responsive to conditions that increase global metabolic rate. Any change in global VO2 must be taken into consideration during the interpretation of peripheral VO2 measurements in neonates.