[Effect of enhanced ultrasound guiding on brachial plexus block]

To assess whether the enhanced imaging technology can improve the needle visibility during ultrasound-guided auxillary brachial plexus block.

After obtaining informed consent, 60 ASA (American Society of Anesthesiologists) I-II patients undergoing forearm or hand surgery were enrolled in this prospective, randomized, double-blind study. The patients were randomly assigned to two groups, the common image group (n=30) and enhanced image group (n=30). Ultrasound was used in guiding the block of the four branches of brachial plexus, i.e. the median, radial, ulnar and musculocutaneous nerves. In the enhanced image group a special function key "Multi-beam enhance" (MBe) was turned on during the needle insertion. After the nerve stimulator identification of the median, radial, ulnar and musculocutaneous nerves, 10 mL of 0.5% ropivacaine was injected near each nerve. The operating time, the visibility of the needle, the depth of each nerve, the onset time of the block, and the complications related to the block were assessed and recorded.

The operating time was significantly shorter in the enhanced image group compared with the common image group [(2.63±0.81) min vs. (5.07±1.89) min, P=0.01]. The visibility of the needle was better in enhanced image group when the radial and musculocutaneous nerve blocks were performed (P<0.05).

The enhanced image technology can reduce the operating time and improve the visibility of the needle during the peripheral nerve block for the nerve which is relatively deep.