Perineural and Intravenous Dexamethasone and Dexmedetomidine: Network Meta-analysis of Adjunctive Effects on Brachial Plexus Block

 

Anaesthesia 2020. https://doi.org/10.1111/anae.15288

Sehmbi, H., Brull, R., Ceballos, K.R., Shah, U.J., Martin, J., Tobias, A., Solo, K. and Abdallah, F.W.

Aim of Study

Compare and rank the effects of perineural and intravenous dexamethasone and dexmedetomidine as adjuncts in supraclavicular block

Design and Location

Literature review and Network Meta-Analysis

Methodology

Prospective registration of protocol.

Extensive literature review of ‘dexamethasone’, ‘dexmedetomidine’, ‘supraclavicular brachial plexus block’, ‘local anaesthesia’, ‘randomised controlled trial’.

Review of results by 2 authors, mediations by a third.

Network meta-analysis in accordance with PRISMA-NMA.

Primary Outcome

Duration of sensory blockade following supraclavicular brachial plexus block

Secondary Outcomes

Duration of motor blockade following supraclavicular brachial plexus block

Statistics

Continuous data was reported as mean and standard deviation. Differences between each pairwise comparison were measured using the weighted mean difference. Odds ratios with confidence intervals were used for estimating difference in effect of dichotomous outcomes.

Results

Prolongation of supraclavicular blockade (WMD, in minutes, versus control group)

Sensory Blockade

Motor Blockade

Analgesic Blockade

Dexamethasone

Intravenous

+477.4

+288.7

+477.8

Dexamethasone

Perineural

+411.4

+294.4

+518

Dexmedetomidine

Intravenous

+66.3

+60.5

+60.6

Dexmedetomidine

Perineural

+283.3

+257.9

+318.2

Conclusions/Discussions

Overall, studies showed that dexamethasone produced greater prolongation of supraclavicular nerve blockade than dexmedetomidine.

Intravenous dexamethasone more effective than perineural dexamethasone at prolonging sensory blockade. This is contrary to previous studies and the authors postulated that this may relate to systemic absorption of dexamethasone at different block sites.

Dexmedetomidine is only effective at prolonging supraclavicular nerve blockade when given perineurally; this suggests that its mechanism of action is local rather than systemic.

Stated Limitations from the Study

The overall quality of evidence from the study ranged from very low to low due to inherent bias in the source trials.

Potential confounding factors included local anaesthetic selection and dose, concurrent use of opioids and other adjuncts. Also discussed the possible differences in effects at different block sites – this means that results are unlikely to be valid for adjunct effect at other block sites.

Discussion from Journal Club Meeting (?Change of Practice)

Overall an interesting study but unlikely to change practice as:

  • No information on the rates of nerve injury associated with use of adjuncts
  • Unsure whether preservative free dexamethasone is available – though this is more important when using adjuncts close to the intrathecal space than in peripheral nerve blockade.
  • Ideally would like to prolong sensory block more than motor block and therefore continuing iv dexamethasone and gaining the anti-emetic benefits is likely to offer the greatest patient benefit.
  • Block prolongation in itself is not always desirable and certain lists are more amenable to shorter blockade and earlier return to normal function, eg in relatively minor hand surgery.

Summary by Dr R Fry. Journal Club Meeting 26 November 2020.

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