Abstract

Aim: To evaluate peripheral oxygen consumption (Vo₂) measurements using near infrared spectroscopy (NIRS) with arterial occlusion in healthy term neonates by studying the effect of limb cooling on peripheral and global Vo₂.

Subjects and methods: Twenty two healthy term neonates were studied. Peripheral Vo₂ was measured by NIRS using arterial occlusion and measurement of the oxyhaemoglobin (HbO₂) decrement slope. Global Vo₂ was measured by open circuit calorimetry. Global and peripheral Vo₂ was measured in each neonate before and after limb cooling.

Results: In 10 neonates, a fall in forearm temperature of 2.2°C (mild cooling) decreased forearm Vo₂ by 19.6% (p < 0.01). Global Vo₂ did not change. In 12 neonates, a fall in forearm temperature of 4°C (moderate cooling) decreased forearm Vo₂ by 34.7% (p < 0.01). Global Vo₂ increased by 17.6% (p < 0.05).

Conclusions: The NIRS arterial occlusion method is able to measure changes in peripheral Vo₂ induced by limb cooling. The changes are more pronounced with moderate limb cooling when a concomitant rise in global Vo₂ is observed. Change in peripheral temperature must be taken into consideration in the interpretation of peripheral Vo₂ measurements in neonates.