Ultrasound - a boon for distal peripheral nerve blocks.

The foray of ultrasound into regional anesthesia has revolutionized the practice of anesthesia. This technological advancement is a shot in the arm for regional anesthesia enthusiasts, thereby making nerve block placement more precise and safer. Ultrasound has caught the imagination of anesthesiologists worldwide; there is an ever increasing number of anesthesiologists who are gaining expertise in the appropriate clinical use of ultrasound.

The current literature is flooded with information indicating a level 1b evidence to advocate a grade A recommendation that ultrasound guidance provides a modest improvement in block onset and quality.[1] There is also evidence that indicates that ultrasound is beneficial for several block performance outcomes, including block performance time, incidence of vascular puncture, reduction in the number of needle passes, shortening sensory block onset time and improving block success.[2]

Distal Peripheral nerve blocks with ultrasound have numerous applications in day care procedures, as rescue blocks for proximal block failure and also to provide site specific analgesia in certain pain syndromes. Distal nerve blocks are useful in several hand and wrist procedures like carpal tunnel release, trigger finger, mallet finger, finger injuries etc. Clear pathways have been established for successful block performance. The incidence of neural injury in distal blocks is far less as compared to proximal nerve blocks and this is attributed to increase in the non-neural connective tissue in the distal nerves. Hence accidental needle injury produces less neural damage in peripheral nerves.[3] Anatomical variations occur to a great extent in the course of the nerves of the upper extremity.[3] Ultrasound guidance has definitely helped us to locate the nerves despite their varied course. The main disadvantage of these blocks is the inability to use the tourniquet.

However skills to effectively use the ultrasound for successful performance of nerve blocks need to be mastered based on the best evidence available from systematic reviews.[4] The future promises to be more exciting, as the advancements made in ultrasound technology usher in a new highway of easy, effective and safe distal peripheral nerve blocks.