Effect of limb cooling on peripheral and global oxygen consumption in neonates

Abstract

Aim: To evaluate peripheral oxygen consumption (VO 2 ) measurements using near infrared spectroscopy (NIRS) with arterial occlusion in healthy term neonates by studying the effect of limb cooling on peripheral and global VO 2 . Subjects and methods: Twenty two healthy term neonates were studied. Peripheral VO 2 was measured by NIRS using arterial occlusion and measurement of the oxyhaemoglobin (HbO 2 ) decrement slope. Global VO 2 was measured by open circuit calorimetry. Global and peripheral VO 2 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 VO 2 by 19.6% (p < 0.01). Global VO 2 did not change. In 12 neonates, a fall in forearm temperature of 4°C (moderate cooling) decreased forearm VO 2 by 34.7% (p < 0.01). Global VO 2 increased by 17.6% (p < 0.05). Conclusions: The NIRS arterial occlusion method is able to measure changes in peripheral VO 2 induced by limb cooling. The changes are more pronounced with moderate limb cooling when a concomitant rise in global VO 2 is observed. Change in peripheral temperature must be taken into consideration in the interpretation of peripheral VO 2 measurements in neonates.

Foot Pulse Oximeter Perfusion Index Correlates with Calf Muscle Perfusion Measured by Near-Infrared Spectroscopy in Healthy Neonates

“…Neonatal calf and forearm VO 2 were measured by NIRS on both arterial and venous occlusion, but Hassan et al 10 demonstrated that arterial occlusion produces more consistent results; they used arterial occlusion to investigate the effects of a change in global metabolic rate on peripheral oxygen consumption, 12 and the effect of limb cooling on peripheral and global oxygen consumption. 11 As for VO 2 We agree with his results because this method gave us a lower coefficient of variation than venous occlusion, as well as a lower VO 2 value (0.3 mM/100 ml/minute) than the 3.2 mM/100 ml/ minute obtained using venous occlusion. Hassan et al 11 reported 10.4 mM/100 ml/minute for arterial occlusion and 14.8 mM/ 100 ml/minute for venous occlusion.…”

“…To the best of our knowledge, this is the first time that foot PI, measured by pulse oximetry, is compared with parameters relating to the peripheral perfusion and oxygen consumption measurable by NIRS. [10][11][12]15,16,18,22 Only recent developments of pulse oximetry have enabled foot PI to be calculated. 2,3 Although the mechanisms underlying PI changes remain to be elucidated, local skin vasoconstriction appears to be the most likely reason for significantly lower PI readings in very sick patients.…”

“…Given the lack of other noninvasive methods, NIRS has been the only bedside clinical tool available in the last few years for evaluating muscle circulatory status in healthy and sick neonates and many significant clinical studies have been published. [8][9][10][11][12]16,18,22,25 NIRS was combined in our study with arterial/venous occlusion maneuvers to measure local muscle BF, VO 2 , and SvO 2 . 9,10,22 Using this NIRS approach, FOE proved to be a better indicator of the need for transfusion in anemia than hemoglobin concentration.…”

“…(1) mM O 2 /100 ml/minute ¼ 9.3 mM O 2 cm/min; 11,12 (2) mM O 2 /100 ml/minute is comparable with ml O 2 /kg/minute, 19 assuming that a mole of a gas, at body temperature and sea level, corresponds to a 25.4 l (Avogadro's law); and 1 kg corresponds to 1000 ml, assuming a muscle density of 1.06 g/ml. 20 Data Analysis and Statistics All parameters were checked for normal distribution using the Kolmogorov-Smirnov test procedure.…”

“…6 Near-infrared spectroscopy (NIRS) has been used largely in neonates for the noninvasive assessment of brain tissue oxygenation 7 and, less often, to evaluate limb oxygenation. [8][9][10][11][12] Considering that: (1) the spot measurement of BF and VO 2 by NIRS takes at least 20 minutes; and (2) the accuracy of NIRS changes is limited because path length and its changes are not known, 7 the foot PI measured by pulse oximetry seems to be more feasible than indirect NIRS methods for monitoring peripheral perfusion in the neonatal intensive care unit. We hypothesized that foot PI could also adequately evaluate limb perfusion.…”