Dexamethasone as an Adjuvant to Peripheral Nerve Block

A peripheral nerve block is a technique which utilized to provide analgesic or anaesthetic effect.

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Key take away

The peripheral nerve block is the postoperative analgesia method. But due to its short-term effects, there is a need for alternative analgesic, which enhances the analgesic duration of peripheral nerve block. Therefore, the present meta-analysis study evaluated that the low to moderate-quality evidence suggests that when used as an adjuvant to peripheral nerve block in upper limb surgery, both perineural and intravenous Dexamethasone may prolong the duration of sensory block and are useful in reducing postoperative pain intensity.

Background

A peripheral nerve block is a technique which utilized to provide analgesic or anaesthetic effect. However, its analgesic effects present only for a few hours. Various adjuvants are used to enhance its analgesic efficacy, including perineural or intravenous Dexamethasone. This study aimed to determine the comparative perineural Dexamethasone safety and efficacy versus placebo, perineural Dexamethasone versus intravenous Dexamethasone, and intravenous Dexamethasone versus placebo when included to peripheral nerve block to manage postoperative pain among subjects going through surgery.

Method

The MEDLINE, Web of Science, Cochrane Central Register of Controlled Trials, Scopus, DARE, and Embase searched from inception to 25 April 2017 for data. Google Scholar and meeting abstracts from the American Society of Anesthesiologists, trial registry databases, the American Society of Regional Anesthesia, the European Society of Regional Anaesthesia, and the Canadian Anesthesiologists' Society were also searched to collect the data.

Result

A total of 35 trials comprised 2702 individuals from 15 to 78 years old were selected. Out of these, patients from 33 studies went through upper limb surgery and from two under lower limb surgery. Thirteen studies were found to have low and 22 with the high/ unclear risk of bias.

Perineural Dexamethasone versus placebo:

The perineural Dexamethasone group exhibited a considerably longer duration of sensory block, lower postoperative pain at 12 hours and one day and lowered cumulative 24-hour postoperative opioid consumption than the placebo group. At 48 hours no significant difference was noticed. At 12 hours, the quality of evidence for postoperative pain intensity noticed to be very low and remained low for other remaining outcomes.

Intravenous Dexamethasone versus placebo:

The intravenous Dexamethasone group showed a considerably longer duration of sensory block, lower postoperative pain intensity at 12 hours and one day and lowered cumulative 24-hour postoperative opioid intake as compared to placebo. This group also exhibited no remarkable difference at two days. At 24 hours, the quality of evidence for postoperative pain intensity and duration of sensory block noticed to be very moderate and remained low for other remaining outcomes.

Perineural versus intravenous Dexamethasone

The perineural Dexamethasone group exhibited a significantly longer duration of sensory block and lowered postoperative pain intensity at 12 hours and 24 hours than placebo, but MD did not exceed the pre-evaluated minutest essential difference of 1.2 on the Numerical Rating Scale/Visual Analogue Scale; consequently the outcomes are not significant clinically. At 24 and 48 hours, no significant difference was noticed in the cumulative postoperative opioid intake and severity of postoperative pain, respectively. At 24 hours, the quality of evidence for postoperative pain intensity and duration of sensory block noticed to be very moderate and remained low for other remaining outcomes.

The incidence of severe adverse events:

A total of five severe adverse effects were noticed. One individual of perineural Dexamethasone and placebo group showed one block-related (pneumothorax) adverse event, but no group allocation was outlined. The groups were comparing perineural Dexamethasone, intravenous Dexamethasone and placebo exhibited four non-block-related events. Two subjects of placebo group needed hospitalization within one week of surgery; one for bowel infection and one for a fall. One participant from intravenous Dexamethasone group showed pneumonia, and one from placebo group showed Complex Regional Pain Syndrome Type I. But, due to the sparse number of events the quality of evidence was very low.

Conclusion

Both intravenous and perineural Dexamethasone, when used as an adjuvant to peripheral nerve block in upper limb surgery, showed significant efficacy in decreasing opioid consumption and postoperative pain intensity along with the extent the duration of sensory block, as per the low to moderate quality evidence. However, not enough evidence was found regarding the Dexamethasone efficacy as an adjuvant to peripheral nerve block in lower limb surgeries and children. The persons who are at the risk of Dexamethasone-related adverse events were not suitable for this review. The nine in process trials enrolled at ClinicalTrials.gov may change the outcomes of this study.