[Addition of fentanyl to adrenalinized lidocaine for the brachial plexus block]

This study was designed to investigate the effects of fentanyl associated with lidocaïne in a solution used to perform axillary brachial plexus nerve block. Adrenergic, sensory and motor nerve blocks have been studied separately and compared to a control group receiving lidocaine without fentanyl. For each type of fibre, the degree of block was measured on, 2, 3, 4, 5 and 10 minutes after injection and the result were studied by variance analysis. Axillary nerve blocks were performed in two different hospitals by two anesthesiologists. After giving informed consent, the patients were randomly allocated in two groups receiving 30 ml 1.5% lidocaine with 1/200,000 epinephrine, with or without fentanyl 100 mu. There were no statistical differences between the two groups as far as adrenergic nerve block was concerned, whereas sensory and motor nerve blocks were significantly more important as soon as five minutes after injection and lasted longer when fentanyl was added to the solution. This enhancement of intensity and duration of sensory and motor nerve blocks when fentanyl is added allows a reduction of the quantity of lidocaine required, and shortens the delay between injection and complete blockade.