FENTANYL PROLONGS LIDOCAINE SPINAL-ANESTHESIA WITHOUT PROLONGING RECOVERY

Lidocaine spinal anesthesia is a popular anesthetic for short procedur es due to its brief duration. The addition of fentanyl may improve the quality and duration of lidocaine spinal anesthesia. Eight volunteers received plain lidocaine 5% in dextrose (50 mg) both with and without 20 mu g of fentanyl in a randomized, double-blind, cross-over fashion . Sensory analgesia was assessed with pinprick, cold, touch, transcuta neous electrical stimulation equivalent to surgical incision, and dura tion of tolerance of pneumatic thigh tourniquet. Motor block was asses sed with isometric force dynamometry. Regression of pinprick, touch, a nd cold was prolonged with fentanyl. Duration of tolerance of electric al stimulation at the umbilicus, hip, knee, and ankle was increased wi th fentanyl (181% increase from plain lidocaine on average; P < 0.01). Duration of tolerance of tourniquet-induced pain was increased by an average of 48% with addition of fentanyl (P = 0.02). Neither motor blo ck nor time to void was prolonged with fentanyl. Pruritus occurred in all subjects receiving fentanyl but was treated easily and were well t olerated. We recommend the addition of 20 mu g of fentanyl to lidocain e spinal anesthesia as a means to improve duration of sensory anesthes ia without prolonging recovery of motor function or time to micturitio n.