COMBINED EFFECT OF PATIENT VARIABLES ON SENSORY LEVEL AFTER SPINAL 0.5-PERCENT PLAIN BUPIVACAINE

Background: The combined effect of age, weight height, and vertebral c olumn length (VCL) on the distribution of isobaric 0.5% bupivacaine wi thin the subarachnoid space is unclear. The aim of the present study w as to evaluate the combined influence of these patient variables on th e upper sensory level and on its predictability. Methods: In 100 patie nts who were above the age of 49 years, the age, weight, height, VCL, body surface (BS), and body mass index (BMI) were noted. Spinal punctu re and subarachnoid drug administration were standardized. Cephalad sp read of spinal anaesthesia (SA) was assessed by loss of temperature se nsation and pinprick discrimination 15, 30, 60, 90, and 120 min follow ing subarachnoid injection of 18 mg of plain 0.5% bupivacaine. Linear regression analysis was performed for each of the patient variables an d the cephalad segmental spread of anaesthesia. Multiple regression an alysis was used to test for combined correlation between patient varia bles and the sensory level of SA. Results: No linear correlation was f ound between the patient variables and the sensory level of anaesthesi a. In contrast, multiple regression analysis revealed that age (P<0.01 ), weight (P<0.05), and height (P<0.01) significantly contributed to t he spread of anaesthesia. A squared multiple comparison coefficient be tween 0.10 and 0.21, however, is an indication that the predictive val ue of the combined variables remained rather low. Conclusion: Multiple regression analysis revealed that age, weight, and height significant ly correlated with the sensory level after subarachnoid injection of p lain bupivacaine. The low predictive value suggests that patient facto rs other than age, weight, or height add to cephalad spread of SA.