Background:
Peripheral nerve blocks allow avoidance of multiple anesthetics in the OR for burn patients. One disadvantage of extremity blocks is loss of functionality due to motor blockade. We present a patient with an upper extremity burn injury requiring multiple dressing changes managed with dual continuous median and radial peripheral nerve block catheters placed under ultrasound. No such combination of distal nerve block catheters placed under ultrasound has been reported. Here, we hope to illustrate a novel continuous nerve block technique that preserves motor function and is almost purely sensory--a functional block.
Case Description:
A 51 year old male with a past medical history of COPD was admitted with a 0.25% total body surface area burn to the left index finger. His pain at baseline and during dressing changes was not controlled with IV and PO narcotics. Regional anesthesia was consulted for placement of a nerve block catheter. An infraclavicular block was placed, but the patient complained of loss of function in his left upper extremity. To avoid motor blockade, we used ultrasound guidance to place continuous nerve block catheters of the distal radial and median nerves. The patient had immediate pain relief; his baseline pain score decreased from 9 to 1/10, he tolerated dressing changes with minimal pain, and he was able to use the extremity, including intrinsic hand muscles, during the duration of the block. The infusion rates were decreased on both catheters on day 2 due to leakage from catheter sites causing dislodgement of clear dressings. Catheters were removed on catheter day 4 as patient noted tenderness and the regional team noted slight erythema on rounds. The patient was placed on antibiotics for treatment of presumed bacterial infection. The erythema and tenderness at catheter sites improved and he was discharged on oral antibiotics when his burn was adequately healed.
Discussion: This is the first report of continuous distal motor sparing blocks of the median and superficial radial nerves. In distal continuous nerve blocks, the rate of infusion of continuous distal nerve blocks needs to be low, as leakage from the site makes adhesion of dressings difficult and may increase the risk of infection. Despite superficial location of the nerves, there were no issues with catheter dislodgement. Continuous nerve blocks placed after hand surgery in the ulnar and median nerves and a case of a superficial radial continuous nerve block in a complex regional pain syndrome patient has been reported. Here, we demonstrate further that distal continuous nerve blocks that are motor sparing, which we call a functional block, provides excellent and prolonged analgesia while preserving motor function in the upper extremity, including in both flexor digitorum and the extensors of the fingers. By allowing for early movement, functional bocks may decrease scarring, increase range of motion and improve functional outcomes.
