Article Text
Abstract
Background and Objectives The purpose of this study was to evaluate the effect of spinal anesthesia in V̇2 in a uniform high-risk patient population and also the relationship between dermatomal level of block and V̇O2, neither of which has been investigated previously.
Methods The effect of spinal anesthesia on V̇O2 was studied in 17 diabetic patients undergoing lower limb peripheral vascular surgery. Measurements were made before and 15 minutes after administration of a tetracaine spinal anesthetic. Values for V̇O2 and oxygen delivery (V̇O2) were derived from cardiac output as measured by thermodilution, hemoglobin concentration, and arterial and mixed venous blood gas analysis. The dermatomal level of the sensory block was determined by use of a hand-held nerve stimulator.
Results Mean V̇O2 decreased by 27.7% (P = .001) (95% confidence limits, decrease of 22.4-90.4%). Mean ḊO2 and arterial blood gases were unchanged, and the mean postspinal oxygen extraction ratio (V̇OO2ḊO2) decreased by 20.5% (P = .002) (95% confidence limits, decrease of 9.1-32.3%). There was a relationship between changes in V̇OO2 and sensory block height (P = .029).
Conclusions Spinal anesthesia in diabetic patients is associated with a reduction in V̇OO2, the extent of which appears to be, at least in part, a function of the level of spinal sensory block.
- oxygen consumption
- oxygen extraction
- spinal anesthesia
- tetracaine
- peripheral vascular surgery
- diabetes