Abstract

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 occlusion 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.