Prolongation of isobaric bupivacaine spinal anesthesia with epinephrine and clonidine for hip surgery in the elderly.

The effects of vasoconstrictors on the duration of isobaric bupivacaine spinal anesthesia are unknown. A prospective controlled study was conducted on 60 ASA class II or III patients aged 75 yr or more who were scheduled for spinal anesthesia for orthopedic hip surgery. The subjects were randomly allocated into three groups. All patients received 15 mg bupivacaine plain solution in 4 ml in the horizontal position. Group I patients received bupivacaine plus 1 ml normal saline; group II patients received bupivacaine plus 0.2 mg epinephrine; group III patients received bupivacaine plus 0.15 mg clonidine. The segmental level of sensory loss was tested using forceps. In one case in group III, anesthesia was unsatisfactory. The time course required for maximal spread of the sensory blockade did not differ in the three groups. No difference was observed between mean highest levels of sensory anesthesia. The mean time to two-segment regression from the highest level was significantly longer in group III than in groups I and II. Mean time for regression to the L2 segment was also significantly longer in groups II and III than in group I. This time tended to increase more with the bupivacaine plus clonidine solution than with the bupivacaine plus epinephrine solution. Significant prolongation of motor block was also associated with the addition of clonidine.