Measurement of peripheral oxygen utilisation in neonates using near infrared spectroscopy: comparison between arterial and venous occlusion methods

The aim of this study was to develop an arterial occlusion method and compa re it with the venous occlusion method for measurement of peripheral oxygen utilisation in neonates using near infrared spectroscopy (NIRS). Twenty he althy neonates were studied. Arterial occlusion was produced by inflating a neonatal blood pressure cuff to 100 mmHg for 30-40 s and oxygen utilisatio n (VO2) was calculated using the HbO(2) decrement slope following occlusion . Venous occlusion was produced by inflating the cuff to 30 mmHg for 15-20 s and VO2 was calculated by: VO2 = HbT x 4 x (SaO(2)-SvO(2)), where SaO(2) is the arterial oxygen saturation measured by pulse oximetry and SvO(2) is the venous oxygen saturation measured by NIRS. Each baby had a minimum of t hree arterial and three venous occlusions. Criteria were developed for acce ptance/rejection of an occlusion. Using the arterial method, the mean VO2 w as 1.12 mM cm(-1) O-2/min (S.D. = 0.25), (95% CI = 1.00-1.24 mM cm(-1) O-2/ min). The coefficient of variation was 6.6+/-4.1%. Using the venous method, the mean VO2 was 1.60 mM cm(-1) O-2/min (S.D. = 0.48), (95% CI = 1.38-1.82 mM cm(-1) O-2/min), The coefficient of variation was 12.6+/-5.7%. The corr elation between the two methods was weak (r = 0.28 and r(2) was 0.08). The mean difference between the two methods was 0.47 mM cm(-1) O-2/min (S.D. = 0.51). The limits of agreement were - 0.53 to 1.47 mM cm(-1) O-2/min. The a rterial method gives more consistent results. (C) Elsevier Science Ireland Ltd. All rights reserved.