RESUMEN
BACKGROUND: The prolongation of spinal anesthesia by using clonidine through the oral, intravenous and spinal route has been known. The new alpha 2 agonist, dexmedetomidine has been proved to prolong the spinal anesthesia through the intrathecal route. We hypothesized that dexmedetomidine when administered intravenously following spinal block, also prolongs spinal analgesia. METHODS: 48 patients were randomly allocated into two equal groups following receiving spinal isobaric bupivacaine 12.5 mg. Patients in group D received intravenously a loading dose of 1 microg/kg dexmedetomidine over 10 min and a maintenance dose of 0.5 microg/kg/hr. Patients in group C (the control group) received normal saline. The regression times to reach S1 sensory level and Bromage 0 motor scale, hemodynamic changes and the level of sedation were recorded. RESULTS: The duration of sensory block was longer in intravenous dexmedetomidine group compared with control group (261.5 +/- 34.8 min versus 165.2 +/- 31.5 min, P < 0.05). The duration of motor block was longer in dexmedetomidine group than control group (199 +/- 42.8 min versus 138.4 +/- 31.3 min, P < 0.05). CONCLUSION: Intravenous dexmedetomidine administration prolonged the sensory and motor blocks of bupivacaine spinal analgesia with good sedation effect and hemodynamic stability.