Evidence basis for ultrasound-guided block characteristics: onset, quality, and duration.

Background And Objectives: This systematic review summarizes existing evidence for superior onset, quality, and duration of block for ultrasound (US) guidance versus other techniques for nerve localization.

Methods: MEDLINE was systematically searched from 1966 to September 2009 for randomized controlled trials (RCTs) comparing US guidance to another technique for peripheral nerve blocks.

Results: Sixteen RCTs were identified for upper-extremity peripheral nerve blocks and 8 for lower extremity. Jadad scores for quality of RCT ranged from 1 to 5, with a median of 2. For upper-extremity blocks, 9 (60%) of 15 RCTs reported faster onset of block, 4 (25%) of 16 reported better quality of block, and 1 (17%) of 6 reported longer duration of block with US. Only 1 RCT reported that US was inferior in any outcome. For lower-extremity blocks, 5 (71%) of 7 RCTs reported faster onset, 5 (63%) of 8 reported better quality, and none of 3 RCTs reported longer duration of blocks. No RCTs reported that US was inferior in any outcome.

Conclusions: There is level 1b evidence to make a grade A recommendation that US guidance provides a modest improvement in block onset and quality of peripheral nerve blocks. Ultrasound is rarely inferior to other techniques.