https://rapm.bmj.com/content/rapm/34/2/134-170.full.pdf

Lower extremity regional anesthesia: essentials of our current understanding.

Background Brachial plexus nerve blocks (BPBs) have analgesic and opioid sparing benefits for upper extremity surgery. Single-injection techniques are limited by the pharmacological duration and therapeutic index of local anaesthetics (LAs). Continuous catheter techniques, while effective can present management challenges. Off-label use of perineural dexamethasone as an LA adjuvant has been utilized to prolong single-injection techniques. The objectives of this systematic review and meta-analysis are to assess the contemporary literature and quantify the effects of dexamethasone on BPB. Methods The authors searched for randomized, placebo-controlled trials that compared BPB performed with LA alone with that performed with LA and perineural dexamethasone. Meta-analysis was performed using a random effects model with subgroup analysis stratified by LA (long vs intermediate). The primary outcome was duration of sensory block or analgesia; the secondary outcomes were motor block duration, opioid consumption, and BPB complications. Results Nine trials (801 patients) were included with 393 patients receiving dexamethasone (4–10 mg). Dexamethasone prolonged the analgesic duration for long-acting LA from 730 to 1306 min [mean difference 576 min, 95% confidence interval (CI) 522–631] and for intermediate from 168 to 343 min (mean 175, 95% CI 73–277). Motor block was prolonged from 664 to 1102 min (mean 438, 95% CI 89–787). The most recent trial demonstrated equivalent prolongation with perineural or systemic administration of dexamethasone compared with placebo. Conclusions Perineural administration of dexamethasone with LA prolongs BPB effects with no observed adverse events. The effects of systemic administration of dexamethasone on BPB must be investigated.

Effects of dexamethasone as a local anaesthetic adjuvant for brachial plexus block: a systematic review and meta-analysis of randomized trials

Background
The present study was designed to test the hypothesis that the increased duration of analgesia caused by adding dexmedetomidine to local anesthetic results from blockade of the hyperpolarization-activated cation (Ih)current.

/pdf/perineural-dexmedetomidine-added-to-ropivacaine-for-sciatic-ao9k4mv6w6.pdf

Perineural Dexmedetomidine Added to Ropivacaine for Sciatic Nerve Block in Rats Prolongs the Duration of Analgesia by Blocking the Hyperpolarization-activated Cation Current

https://rapm.bmj.com/content/rapm/35/Suppl_1/S1.full.pdf

The ASRA evidence-based medicine assessment of ultrasound-guided regional anesthesia and pain medicine: Executive summary.

Upper Extremity Regional Anesthesia

Background Interscalene brachial plexus block (ISBPB) is an effective nerve block for shoulder surgery. However, a 100% incidence of phrenic nerve palsy limits the application of ISBPB for patients with limited pulmonary reserve. We examined the incidence of phrenic nerve palsy with a low-volume ISBPB compared with a standard-volume technique both guided by ultrasound. Methods Forty patients undergoing shoulder surgery were randomized to receive an ultrasound-guided ISBPB of either 5 or 20 ml ropivacaine 0.5%. General anaesthesia was standardized. Both groups were assessed for respiratory function by sonographic diaphragmatic assessment and spirometry before and after receiving ISBPB, and after surgery. Motor and sensory block, pain, sleep quality, and analgesic consumption were additional outcomes. Statistical comparison of continuous variables was analysed using one-way analysis of variance and Student's t -test. Non-continuous variables were analysed using χ 2 tests. Statistical significance was assumed at P Results The incidence of diaphragmatic paralysis was significantly lower in the low-volume group compared with the standard-volume group (45% vs 100%). Reduction in forced expiratory volume in 1 s, forced vital capacity, and peak expiratory flow at 30 min after the block was also significantly less in the low-volume group. In addition, there was a significantly greater decrease in postoperative oxygen saturation in the standard-volume group (−5.85 vs −1.50, P =0.004) after surgery. There were no significant differences in pain scores, sleep quality, and total morphine consumption up to 24 h after surgery. Conclusions The use of low-volume ultrasound-guided ISBPB is associated with fewer respiratory and other complications with no change in postoperative analgesia compared with the standard-volume technique.

Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block

Results. The MEAV required to provide effective analgesia was significantly (P¼0.034) reduced to 0.9 ml [95% confidence interval (CI) 0.3–2.8] in the US group from 5.4 ml (95% CI 3.4–8.6) in the NS group. Fewer needle passes were needed to identify the brachial plexus with US (1 vs 3; P,0.0001) and patients had less pain at 30 min after surgery (P¼0.03). Conclusions. US reduces the number of attempts, LA volume, and postoperative pain when compared with NS for ISB.

Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block

Methods. Forty patients undergoing shoulder surgery were randomized to receive an ultrasound-guided ISBPB of either 5 or 20 ml ropivacaine 0.5%. General anaesthesia was standardized. Both groups were assessed for respiratory function by sonographic diaphragmatic assessment and spirometry before and after receiving ISBPB, and after surgery. Motor and sensory block, pain, sleep quality, and analgesic consumption were additional outcomes. Statistical comparison of continuous variables was analysed using one-way analysis of variance and Student’s t-test. Non-continuous variables were analysed using x 2 tests. Statistical significance was assumed at P,0.05. Results. The incidence of diaphragmatic paralysis was significantly lower in the low-volume group compared with the standard-volume group (45% vs 100%). Reduction in forced expiratory volume in 1 s, forced vital capacity, and peak expiratory flow at 30 min after the block was also significantly less in the low-volume group. In addition, there was a significantly greater decrease in postoperative oxygen saturation in the standard-volume group (25.85 vs 21.50, P¼0.004) after surgery. There were no significant differences in pain scores, sleep quality, and total morphine consumption up to 24 h after surgery. Conclusions. The use of low-volume ultrasound-guided ISBPB is associated with fewer respiratory and other complications with no change in postoperative analgesia compared with the standard-volume technique. Br J Anaesth 2008; 101: 549–56

REGIONAL ANAESTHESIA Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block

N. Carmichael

Papers

Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block

Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block

REGIONAL ANAESTHESIA Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block