Alpha2 -receptor agonists as adjuvants for brachial plexus nerve blocks-A systematic review with meta-analyses

Perineural Dexamethasone is More Efficient Than Perineural Dexmedetomidine in Prolonging Popliteal Sciatic and Saphenous Nerve Blocks: A Single-Center, Prospective, Double-Blinded, Randomized Controlled Trial

Purpose

This study aims to assess and compare the effectiveness of perineural dexamethasone (DEX) and perineural dexmedetomidine (DEM) as adjuvant in popliteal sciatic and saphenous nerve blocks, focusing on the duration of analgesia and side effects following major foot and ankle surgeries.

Patients and Methods

Ninety patients scheduled for major foot and ankle surgeries under general anesthesia, who received popliteal sciatic and saphenous nerve blocks, were randomly assigned to one of three groups: (1) control group receiving 0.375% ropivacaine; (2) DEX group receiving 0.375% ropivacaine combined with 10 mg perineural dexamethasone; (3) DEM group receiving 0.375% ropivacaine combined with 0.75 μg/kg perineural dexmedetomidine. The primary outcome measured was the duration of analgesia, defined as the time from the administration of the nerve block to the onset of the first pain sensation in the surgical area. Secondary outcomes included opioid consumption within the first 48 hours post-surgery and the incidence of side effects such as hypotension and bradycardia. (Clinical trial registration number: ChiCTR2100048127).

Results

The time until the first perception of pain was significantly extended in the DEX group (28.0 (3.3) hours) compared to the DEM group (24.1 (1.3) hours) and the control group (17.5 (3.5) hours, P<0.001). Additionally, opioid consumption within the first 24 hours was markedly reduced in both the DEX and DEM groups compared to the control group (P<0.001). However, opioid usage between 0 to 48 hours post-surgery showed no significant differences among the three groups. The DEM group experienced a higher incidence of hypotension and bradycardia compared to both the DEX and control group (P<0.001).

Conclusion

Both 10 mg dexamethasone and 0.75 µg/kg dexmedetomidine effectively prolonged analgesia in patients undergoing major foot and ankle surgery with a popliteal sciatic and saphenous nerve block. However, dexamethasone (10 mg) provided a significantly longer duration of analgesia compared to dexmedetomidine (0.75 µg/kg).

Trial Registration

Chictr.org.cn identifier: ChiCTR2100048127.

Effects of combined dexamethasone and dexmedetomidine as adjuncts to peripheral nerve blocks: a systematic review with meta-analysis and trial sequential analysis

BACKGROUND/IMPORTANCE

The effects of combining dexamethasone and dexmedetomidine on block duration are unclear.

OBJECTIVE

To investigate the effects of combining dexamethasone and dexmedetomidine on block duration.

EVIDENCE REVIEW

Systematic review of randomized controlled trials (RCTs) from Medline, Embase, CENTRAL, CINAHL, the Web of Science, and BIOSIS until June 8, 2023. RCTs with adults undergoing surgery with a peripheral nerve block randomized to combined dexamethasone and dexmedetomidine versus placebo or other adjuncts were eligible. Primary outcome was duration of analgesia. We performed meta-analysis, trial sequential analysis, risk of bias-2, and Grading Recommendations Assessment, Development, and Evaluation assessment.

FINDINGS

We included 9 RCTs with 14 eligible comparisons. The combination of dexamethasone and dexmedetomidine was compared with placebo in three RCTs (173 participants), dexamethasone in seven (569 participants), and dexmedetomidine in four (281 participants). The duration of analgesia was likely increased with the combination versus placebo (mean difference 460 min, 95% CI 249 to 671) and versus dexmedetomidine (mean difference 388 min, 95% CI 211 to 565). The duration was likely similar with the combination versus dexamethasone (mean difference 50 min, 95% CI -140 to 239). The certainty of the evidence was moderate because most trials were at high risk of bias.

CONCLUSIONS

Combined dexamethasone and dexmedetomidine likely increased the duration of analgesia when compared with placebo and dexmedetomidine. The combination likely provided a similar duration of analgesia as dexamethasone. Based on this systematic review, it seems reasonable to use dexamethasone as the sole adjunct if the goal is to increase the duration of analgesia.

Primary outcomes and anticipated effect sizes in randomised clinical trials assessing peripheral and truncal nerve blocks: a systematic scoping review

BACKGROUND

Peripheral and truncal nerve blocks provide effective analgesia facilitating perioperative care. However, thresholds for clinically relevant effects remain undetermined and are left for clinicians to choose. These choices are fundamental for sample size calculations and interpretation of study results. This systematic scoping review aimed to create an overview of primary outcomes and anticipated effect sizes in randomised clinical trials assessing peripheral and truncal nerve blocks.

METHODS

We searched Cochrane Library's CENTRAL, Medline, and Embase for randomised trials in English in 10 major anaesthesia journals investigating single-injection ultrasound-guided peripheral and truncal nerve blocks for adults undergoing surgery. The primary outcome was the anticipated effect sizes for primary outcomes. Secondary outcomes included reporting of sample size calculations and statistically significant primary outcomes below anticipated effect sizes.

RESULTS

The most frequently reported primary outcomes were postoperative pain, analgesic consumption, quality of recovery, mobilisation, and block performance. Median anticipated effect sizes were: 0-24 h opioid consumption: 9 mg i.v. morphine equivalents; pain at rest and during movement: 2 points on Numeric Rating Scale 0-10; quality of recovery: 10 points on Quality of Recovery-40 scale and 8 points on Quality of Recovery-15 scale. Adequate sample size calculations were reported in 85% (156/183) and 91% (29/32) of trials assessing continuous outcomes and dichotomous outcomes, respectively. Statistically significant primary outcomes failed to reach anticipated effect sizes in 24% (24/99) of trials, and only one trial addressed this disparity in the trial conclusion.

CONCLUSIONS

The presented outcomes and effect sizes from published trials on peripheral and truncal nerve block literature can be used in future trials to increase homogeneity in regional anaesthesia research.

Effect of oral clonidine on pain reduction in patients with opioid use disorder in the emergency department: A randomized clinical trial

AIMS

Pain can create physical and psychosocial discomfort. Pain management of patients with opioid misuse history can be challenging, in part due to their tolerance to opioids. Clonidine is an alpha-2 agonist that has been used for the reduction of anxiety and pain. The aim of this study was to investigate the effect of oral clonidine on pain outcomes in patients with a history of opioid use disorder presenting with orthopaedic fractures in the emergency room.

METHODS

In this blinded clinical trial in the emergency department, 70 opioid-dependent patients with orthopaedic fractures were divided into a control group of 35 and an intervention group of 35 subjects. Initially, 0.2 mg of oral clonidine was given to the intervention group and the control group received placebo tablets. Pain levels were recorded based on the Numerical Rating Scale rating before intervention, at 30 min, 1 h after intervention and at disposition from the emergency room (3-6 h after intervention). The total morphine requirement was also recorded.

RESULTS

The pain score of the clonidine group was significantly lower than that of the control group at 1 h and at disposition time. The amount of morphine required was significantly reduced in the clonidine group (P < 0.05). Oral clonidine had no significant effect on pulse rate. Oral clonidine was more effective for pain reduction in lower limb injuries.

CONCLUSION

Oral clonidine significantly reduced pain and the need for morphine in opioid-dependent patients with orthopaedic fractures.

Primary outcomes and anticipated effect sizes in randomised clinical trials assessing adjuncts to peripheral nerve blocks: A scoping review

BACKGROUND

Prolonging effects of adjuncts to local anaesthetics in peripheral nerve blocks have been demonstrated in randomised clinical trials. The chosen primary outcome and anticipated effect size have major impact on the clinical relevance of results in these trials. This scoping review aims to provide an overview of frequently used outcomes and anticipated effect sizes in randomised trials on peripheral nerve block adjuncts.

METHODS

For our scoping review, we searched MEDLINE, Embase and CENTRAL for trials assessing effects of adjuncts for peripheral nerve blocks published in 10 major anaesthesia journals. We included randomised clinical trials assessing adjuncts for single-shot ultrasound-guided peripheral nerve blocks, regardless of the type of interventional adjunct and control group, local anaesthetic used and anatomical localization. Our primary outcome was the choice of primary outcomes and corresponding anticipated effect size used for sample size estimation. Secondary outcomes were assessor of primary outcomes, the reporting of sample size calculations and statistically significant and non-significant results related to the anticipated effect sizes.

RESULTS

Of 11,854 screened trials, we included 59. The most frequent primary outcome was duration of analgesia (35/59 trials, 59%) with absolute and relative median (interquartile range) anticipated effect sizes for adjunct versus placebo/no adjunct: 240 min (180-318) and 30% (25-40) and for adjunct versus active comparator: 210 min (180-308) and 17% (15-28). Adequate sample size calculations were reported in 78% of trials. Statistically significant results were reported for primary outcomes in 45/59 trials (76%), of which 22% did not reach the anticipated effect size.

CONCLUSION

The reported outcomes and associated anticipated effect sizes can be used in future trials on adjuncts for peripheral nerve blocks to increase methodological homogeneity.

Perioperative pain management for cleft palate surgery: a systematic review and procedure-specific postoperative pain management (PROSPECT) recommendations

BACKGROUND/IMPORTANCE

Cleft palate surgery is associated with significant postoperative pain. Effective pain control can decrease stress and agitation in children undergoing cleft palate surgery and improve surgical outcomes. However, limited evidence often results in inadequate pain control after cleft palate surgery.

OBJECTIVES

The aim of this review was to evaluate the available evidence and to develop recommendations for optimal pain management after cleft palate surgery using procedure-specific postoperative pain management (PROSPECT) methodology.

EVIDENCE REVIEW

MEDLINE, Embase, and Cochrane Databases were searched for randomized controlled trials and systematic reviews assessing pain in children undergoing cleft palate repair published in English language from July 2002, through August 2023.

FINDINGS

Of 1048 identified studies, 19 randomized controlled trials and 4 systematic reviews met the inclusion criteria. Interventions that improved postoperative pain, and are recommended, include suprazygomatic maxillary nerve block or palatal nerve block (if maxillary nerve block cannot be performed). Addition of dexmedetomidine to local anesthetic for suprazygomatic maxillary nerve block or, alternatively, as intravenous administration perioperatively is recommended. These interventions should be combined with a basic analgesic regimen including acetaminophen and nonsteroidal anti-inflammatory drugs. Of note, pre-incisional local anesthetic infiltration and dexamethasone were administered as a routine in several studies, however, because of limited procedure-specific evidence their contribution to pain relief after cleft palate surgery remains unknown.

CONCLUSION

The present review identified an evidence-based analgesic regimen for cleft palate surgery in pediatric patients.

PROSPERO REGISTRATION NUMBER

CRD42022364788.

Adjuvant Analgesics in Acute Pain - Evaluation of Efficacy

PURPOSE OF THE REVIEW

Acute postoperative pain impacts a significant number of patients and is associated with various complications, such as a higher occurrence of chronic postsurgical pain as well as increased morbidity and mortality.

RECENT FINDINGS

Opioids are often used to manage severe pain, but they come with serious adverse effects, such as sedation, respiratory depression, postoperative nausea and vomiting, and impaired bowel function. Therefore, most enhanced recovery after surgery protocols promote multimodal analgesia, which includes adjuvant analgesics, to provide optimal pain control. In this article, we aim to offer a comprehensive review of the contemporary literature on adjuvant analgesics in the management of acute pain, especially in the perioperative setting. Adjuvant analgesics have proven efficacy in treating postoperative pain and reducing need for opioids. While ketamine is an established option for opioid-dependent patients, magnesium and α2-agonists have, in addition to their analgetic effect, the potential to attenuate hemodynamic responses, which make them especially useful in painful laparoscopic procedures. Furthermore, α2-agonists and dexamethasone can extend the analgesic effect of regional anesthesia techniques. However, findings for lidocaine remain inconclusive.

Combined Dexamethasone and Dexmedetomidine as Adjuncts to Popliteal and Saphenous Nerve Blocks in Patients Undergoing Surgery of the Foot or Ankle: A Randomized, Blinded, Placebo-controlled Clinical Trial

BACKGROUND

Both dexamethasone and dexmedetomidine increase the duration of analgesia of peripheral nerve blocks. The authors hypothesized that combined intravenous dexamethasone and intravenous dexmedetomidine would result in a greater duration of analgesia when compared with intravenous dexamethasone alone and placebo.

METHODS

The authors randomly allocated participants undergoing surgery of the foot or ankle under general anesthesia and with a combined popliteal (sciatic) and saphenous nerve block to a combination of 12 mg dexamethasone and 1 µg/kg dexmedetomidine, 12 mg dexamethasone, or placebo (saline). The primary outcome was the duration of analgesia measured as the time from block performance until the first sensation of pain in the surgical area as reported by the participant. The authors predefined a 33% difference in the duration of analgesia as clinically relevant.

RESULTS

A total of 120 participants from two centers were randomized and 119 analyzed for the primary outcome. The median [interquartile range] duration of analgesia was 1,572 min [1,259 to 1,715] with combined dexamethasone and dexmedetomidine, 1,400 min [1,133 to 1,750] with dexamethasone alone, and 870 min [748 to 1,138] with placebo. Compared with placebo, the duration was greater with combined dexamethasone and dexmedetomidine (difference, 564 min; 98.33% CI, 301 to 794; P < 0.001) and with dexamethasone (difference, 489 min; 98.33% CI, 265 to 706; P < 0.001). The prolongations exceeded the authors' predefined clinically relevant difference. The duration was similar when combined dexamethasone and dexmedetomidine was compared with dexamethasone alone (difference, 61 min; 98.33% CI, -222 to 331; P = 0.614).

CONCLUSIONS

Dexamethasone with or without dexmedetomidine increased the duration of analgesia in patients undergoing surgery of the foot or ankle with a popliteal (sciatic) and saphenous nerve block. Combined dexamethasone and dexmedetomidine did not increase the duration of analgesia when compared with dexamethasone.

EDITOR’S PERSPECTIVE

Dexmedetomidine as an Adjuvant in Peripheral Nerve Block

Peripheral nerve block technology is important to balanced anesthesia technology. It can effectively reduce opioid usage. It is the key to enhance clinical rehabilitation as an important part of the multimodal analgesia scheme. The emergence of ultrasound technology has accelerated peripheral nerve block technology development. It can directly observe the nerve shape, surrounding tissue, and diffusion path of drugs. It can also reduce the dosage of local anesthetics by improving positioning accuracy while enhancing the block's efficacy. Dexmedetomidine is a highly selective drug α₂-adrenergic receptor agonist. Dexmedetomidine has the characteristics of sedation, analgesia, anti-anxiety, inhibition of sympathetic activity, mild respiratory inhibition, and stable hemodynamics. Numerous studies have revealed that dexmedetomidine in peripheral nerve blocks can shorten the onset time of anesthesia and prolong the time of sensory and motor nerve blocks. Although dexmedetomidine was approved by the European Drug Administration for sedation and analgesia in 2017, it has not yet been approved by the US Food and Drug Administration (FDA). It is used as a non-label drug as an adjuvant. Therefore, the risk-benefit ratio must be evaluated when using these drugs as adjuvants. This review explains the pharmacology and mechanism of dexmedetomidine, the effect of dexmedetomidine on various peripheral nerve block as an adjuvant, and compare it with other types of adjuvants. We summarized and reviewed the application progress of dexmedetomidine as an adjuvant in nerve block and look forward to its future research direction.