The Effect of Varied Doses of Epinephrine on Duration of Lidocaine Spinal Anesthesia in the Thoracic and Lumbosacral Dermatomes

UNLABELLED: The efficacy of epinephrine in prolonging spinal analgesia has recently been confirmed in the lumbosacral but not in the thoracic, segments. Most previous studies used doses of epinephrine smaller than 0.3 mg. We studied the effects of 0.2, 0.4, or 0.6 mg of epinephrine added to hyperbaric lidocaine 60 mg in 7.5% dextrose solution for spinal anesthesia. Eighty patients were randomly divided into four groups: Group A received lidocaine without epinephrine, Group B received lidocaine plus 0.2 mL (0.2 mg) of epinephrine 1:1000 solution, Group C received lidocaine plus 0.4 mL (0.4 mg) of epinephrine, and Group D received lidocaine plus 0.6 mL (0.6 mg) of epinephrine. The maximal cephalad sensory level was between T2 and T3 for all groups. The median times for analgesia to regress two and four segments were significantly prolonged in Group D, but not in either Group B or C, compared with those in Group A. Times for regression to T12 and L3 were significantly prolonged in Groups B, C, and D compared with Group A. We conclude that the dose-dependent relationship of spinal analgesia can be applied to epinephrine, and that larger doses prolong lidocaine spinal anesthesia in the thoracic as well as the lumbosacral dermatomes. IMPLICATIONS: Prolongation of lidocaine spinal analgesia by intrathecal epinephrine is established in the lumbosacral, but not in the thoracic, dermatomes. Three doses of epinephrine--0.2, 0.4, and 0.6 mg--were compared. A dose-dependent response and significant prolongation with the 0.6-mg dose in the thoracic dermatomes were confirmed.