Please see Bibliography of References for a list of abstracts, manuscripts and posters.
Lima A, Galvin E, Van Bommel J, Bakker J. Crit Care. 2009;13(Suppl 1):P237.
Introduction: Near infrared spectroscopy (NIRS) is a technique for continuous, noninvasive, bedside monitoring of tissue oxygenation (StO2). The nature of the relationship between the kinetics of StO2 and changes in peripheral circulation has not been investigated. After successful regional anaesthesia blocks, local vasodilation and increased local blood flow occur as a result of blockade of sympathetic nerve fibers. We, therefore, studied the effects of peripheral vasodilation induced by regional anaesthesia blocks on resting StO2 values.
Methods: We recruited healthy adult patients (N=8) scheduled for selective upper limb surgery under axillary sympathetic blocks. StO2 was continuously monitored over the thenar of the blocked arm using InSpectra Model 325 probe (Hutchinson Technology Inc.) from the beginning of the local anesthetic (T0) injection until 30 min was elapsed (T30). The contralateral arm was used as control. Differences between group means were tested by Wilcoxon signed test. P values <0.05 were considered statistically significant.
Results: StO2 values in the arm blocked were significantly higher in all patients after the anaesthesia (Figure). T30 vs. T0: 94±2 vs. 82±3; P=0.002. StO2 did not increase in the control arm.
Conclusions: Peripheral vasodilation increases StO2 in normal conditions
References:
Image 1: Effect of peripheral blood flow variations in the StO2 during regional block