Should continuous rather than single-injection interscalene block be routinely offered for major shoulder surgery? A meta-analysis of the analgesic and side-effects profiles.

BACKGROUND: Major shoulder surgery is associated with moderate-to-severe pain, but consensus on the optimal analgesic approach is lacking. Continuous catheter-based interscalene block (CISB) prolongs the analgesic benefits of its single-injection counterpart (SISB), but concerns over CISB complications and difficulties in interpreting comparative evidence examining major and minor shoulder procedures simultaneously, despite their differences in postoperative pain, have limited CISB popularity. This meta-analysis evaluates the CISB analgesic role and complications compared with SISB for major shoulder surgery. METHODS: We retrieved randomised controlled trials (RCTs) comparing the effects of CISB to SISB on analgesic outcomes and side-effects after major shoulder surgery. Postoperative opioid consumption at 24 h was designated as the primary outcome. Secondary outcomes included 24-48 h opioid consumption, postoperative rest and dynamic pain scores up to 72 h, time-to-first analgesic, recovery room and hospital stay durations, patient satisfaction, postoperative nausea and vomiting, respiratory function, and block-related complications. RESULTS: Data from 15 RCTs were pooled using random-effects modelling. Compared with SISB, CISB reduced 24- and 48-h oral morphine consumption by a weighted mean difference [95% confidence interval] of 50.9 mg [-81.6, -20.2], (P=0.001) and 44.7 mg [-80.9, -8.7], (P<0.0001), respectively. Additionally, CISB provided superior rest and dynamic pain control beyond 48 h, prolonged time-to-first analgesic, enhanced satisfaction, and reduced postoperative nausea and vomiting without complications. CISB caused an 11.0-11.7% decrease in respiratory indices. Result heterogeneity was successfully explained. CONCLUSIONS: High-level evidence indicates that CISB provides superior analgesia up to 48 h after major shoulder surgery, without increasing side-effects, compared with SISB. The importance of CISB-related changes in respiratory indices is questionable.

Evidence basis for using perineural dexmedetomidine to enhance the quality of brachial plexus nerve blocks: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Dexmedetomidine has been proposed as a perineural local anaesthetic (LA) adjunct to prolong peripheral nerve block duration; however, results from our previous meta-analysis in the setting of brachial plexus block (BPB) did not support its use. Many additional randomized trials have since been published. We thus conducted an updated meta-analysis. METHODS: Randomized trials investigating the addition of dexmedetomidine to LA compared with LA alone (Control) in BPB for upper extremity surgery were sought. Sensory and motor block duration, onset times, duration of analgesia, analgesic consumption, pain severity, patient satisfaction, and dexmedetomidine-related side-effects were analysed using random-effects modeling. We used ratio-of-means (lower confidence interval [point estimate]) for continuous outcomes. RESULTS: We identified 32 trials (2007 patients), and found that dexmedetomidine prolonged sensory block (at least 57%, P < 0.0001), motor block (at least 58%, P < 0.0001), and analgesia (at least 63%, P < 0.0001) duration. Dexmedetomidine expedited onset for both sensory (at least 40%, P < 0.0001) and motor (at least 39%, P < 0.0001) blocks. Dexmedetomidine also reduced postoperative oral morphine consumption by 10.2mg [-15.3, -5.2] (P < 0.0001), improved pain control, and enhanced satisfaction. In contrast, dexmedetomidine increased odds of bradycardia (3.3 [0.8, 13.5](P = 0.0002)), and hypotension (5.4 [2.7, 11.0] (P < 0.0001)). A 50-60µg dexmedetomidine dose maximized sensory block duration while minimizing haemodynamic side-effects. No patients experienced any neurologic sequelae. Evidence quality for sensory block was high according to the GRADE system. CONCLUSIONS: New evidence now indicates that perineural dexmedetomidine improves BPB onset, quality, and analgesia. However, these benefits should be weighed against increased risks of motor block prolongation and transient bradycardia and hypotension.