ABSTRACT
The purpose of this study was to compare the effect of intravenous dexmedetomidine with the intravenous propofol adjuvant to spinal intrathecal anesthesia on the duration of spinal anesthesia and hemodynamic parameters during total knee replacement surgery. Seventy five patients were enrolled into this randomized study from the 1[st] of April 2008 till the 30[th] of August 2009 for total knee replacement surgery under spinal anesthesia. They were randomly assigned into three groups, group D, group P and group C. Following intrathecal injection with bupivacaine 12.5 mg in all patients in the three groups, patients in group D received intravenous loading dose of microg/kg/hr dexmedetomidine over 10 minutes and a maintenance dose of 0.2 to 0.5 p,g/kg/hr. Patients in group P received intravenous propofol 4 mg/Kg/hr over 10 min and a maintenance dose of 0.5-2 mg/Kg/hr. Patients in group C [control group] received nothing extra to the regular IV fluid. The regression times to reach SI sensory level and Bromage 0 motor scale, the hemodynamic parameters, the Bispectral Index level of Sedation [BIS], and arterial CO[2] level were recorded. The regression time to reach SI dermatome was 149.4 +/- 14.6 min in group C, 152.8 +/- 16.6 min in group P and 209.6 +/- 25.9 min in group D. The regression to Bromage 0 was!84.6 +/- 22.8 min in group C, 190.0 +/- 21.0 min in group P, and 255.8 +/- 36.7 min in group D. Statistical analysis of regression of sensory and motor block was significant among groups [C vs. D, P vs. D, P < 0.05]. The heart rate was significantly decreased in group D in comparison to groups C and P. Sedation levels were within accepted ranges in groups D and P and not affected in the control group. Minimal respiratory depression occurred in group P and D, clinically it was not significant. Supplementation of spinal anesthesia with intravenous dexmedetomidine or propofol produces good sedation levels without significant clinical hemodynamic changes. Adding dexmedetomidine produces significantly longer sensory and motor block than propofol