Background and objectives: Little is known about the effect of adding epinephrine to local anesthetic solutions on the intensity of sensory block during epidural anesthesia. This study examined development of sensory block during lumbar epidural anesthesia using a cutaneous current perception threshold (CPT) quantitative sensory testing device.
Methods: Twenty ASA I patients who were randomly divided to receive 10 mL 1% lidocaine with (group E) or without (group P) epinephrine 1:200,000. Current perception threshold at 2,000, 250, and 5 Hz stimulation at the trigeminal (V), ninth thoracic (T9), and second lumbar (L2) dermatomes, and the dermatomal levels of block of light touch, temperature, and pinprick discrimination were measured before and every 5 minutes, until 60 minutes after injection of epidural lidocaine.
Results: After epidural administration of lidocaine with epinephrine, all CPT significantly increased at T9 and L2, whereas no increase was detected after epidural plain lidocaine. Areas under the curves, calculated to express overall magnitude and duration of CPT values, were significantly larger in group E than those in group P at 2,000 and 250 Hz at T9. No differences were observed in the maximal levels of loss of cold, pinprick, and touch sensations between both groups.
Conclusions: These results suggest that lumbar epidural anesthesia using 10 mL 1% lidocaine with epinephrine produces a more intense block of both large and small diameter sensory nerve fibers than that with plain lidocaine. It appears, therefore, that the addition of epinephrine improves the quality of sensory block during epidural anesthesia with lidocaine.