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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