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Systematic Review of US vs NS-Guided Nerve Blocks

Title
Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials
Authors
Abrahams MS, Aziz MF, Fu RF, Horn JL
Journal
British Journal of Anaesthesia 2009 Apr; 102(3): 408-17.

 

Study Summary

 

Study design
  • Systematic review of the literature
Study population
  • Randomized controlled trials comparing ultrasound-guided and neurostimulation-guided peripheral nerve blocks.
Intervention
  • Ultrasound-guided peripheral nerve block (US-PNB).
Comparator(s)
  • Neurostimulation-guided peripheral nerve block (NS-PNB).
Main findings
  • They identified 13 studies involving 946 patients that met the inclusion criteria.
  • The relative risk of block failure in US-PNB was 0.41 (95% CI 0.26-0.66, 9 studies).
  • The relative risk for complete sensory block in all nerve territories covered by US-PNB was 1.23 (95%CI 1.07-1.41,5 studies).
  • Block performance time was 1 minute shorter (95% CI 0.4-1.7, 7 studies) in US-PNB.
  • Onset time was 29% faster (95% CI 12-45%, 8 studies) in US-PNB.
  • Duration was 25% longer (95% CI 12-38%, 5 studies) in US-PNB.
  • The relative risk for vascular puncture in US-PNB was 0.16 (95% 0.05-0.47, 4 studies).
  • No other significant differences were observed.

 

Comments on the study

  • This is one of the earliest systematic reviews / meta-analyses examining the question of whether ultrasound-guided peripheral nerve blockade is superior to neurostimulation-guided techniques. As such it is an important paper to be aware of when following the literature on ultrasound-guided regional anesthesia.
  • Nevertheless, although the results of the meta-analyses suggest benefit of ultrasound-guidance with respect to block success, onset, duration and the risk of vascular puncture, it is important to bear in mind that there are methodological limitations. Firstly, only a small number of studies were included, especially for the individual outcomes that were considered. Secondly, there was significant clinical heterogeneity amongst the studies included (children vs adults, anatomical site of block, type and volume of local anesthetic used, neurostimulation technique, etc) and this limits the extent to which the findings can be generalized.
  • Further randomized controlled trials are still needed to establish the efficacy and safety of ultrasound-guidance compared to neurostimulation in peripheral nerve blockade. Future systematic reviews and meta-analyses should also seek to subgroup outcomes by the anatomical area / nerve being blocked.