SPINAL-ANESTHESIA REDUCES OXYGEN-CONSUMPTION IN DIABETIC-PATIENTS PRIOR TO PERIPHERAL VASCULAR-SURGERY

Background and Objectives. The purpose of this study was to evaluate t he effect of spinal anesthesia in VO2 in a uniform high-risk patient p opulation and also the relationship between dermatomal level of block and VO2, neither of which has been investigated previously. Methods. T he effect of spinal anesthesia on VO2 was studied in 17 diabetic patie nts undergoing lower limb peripheral vascular surgery. Measurements we re made before and 15 minutes after administration of a tetracaine spi nal anesthetic. Values for VO2 and oxygen delivery (DO2) were derived from cardiac output as measured by thermodilution, hemoglobin concentr ation, and arterial and mixed venous blood gas analysis. The dermatoma l level of the sensory block was determined by use of a hand-held nerv e stimulator. Results. Mean VO2 decreased by 27.7% (P = .001) (95% con fidence limits, decrease of 22.4-90.4%). Mean DO2 and arterial blood g ases were unchanged, and the mean postspinal oxygen extraction ratio ( VO2/DO2) decreased by 20.5% (P = .002) (95% confidence limits, decreas e of 9.1-32.3%). There was a relationship between changes in VO2 and s ensory block height (P = .029). Conclusions. Spinal anesthesia in diab etic patients is associated with a reduction in VO2, the extent of whi ch appears to be, at least in part, a function of the level of spinal sensory block.