Perineural Low-Dose Dexamethasone Prolongs Interscalene Block Analgesia With Bupivacaine Compared With Systemic Dexamethasone: A Randomized Trial.

BACKGROUND AND OBJECTIVES: Perineural dexamethasone and intravenous (IV) dexamethasone have been shown to prolong peripheral nerve block duration. The effects of perineural and IV dexamethasone have only been compared at doses of 4 mg or greater. This triple-blind, randomized trial examined the effect of 1 mg IV versus perineural dexamethasone on interscalene block (ISB) analgesia duration. METHODS: Patients undergoing ambulatory shoulder arthroscopy received an ultrasound-guided ISB with 15 mL bupivacaine 0.5% and 1 mg preservative-free dexamethasone that was administered perineurally (PeriD) or IV (IVDex). All patients received IV ketorolac and were discharged on naproxen 500 mg 2 times a day plus oxycodone/acetaminophen as needed. Peripheral nerve block duration, pain, opioid consumption, and block satisfaction were assessed via telephone follow-ups. RESULTS: There were 63 PeriD patients and 62 IVDex patients who completed the primary outcome follow-up. The median time until analgesia from the ISB completely wore off was 3.5 hours (95% confidence interval, 1.0-6.0 hours) longer in the PeriD versus IVDex groups; P = 0.007). Time until the pain relief from the ISB began to wear off was also longer in the PeriD versus IVDex group (5.5 hours [95% confidence interval, 2.1-9.0 hours]; P = 0.002). Other secondary outcomes, including opioid consumption, satisfaction, and pain scores, were not different between groups. CONCLUSIONS: In patients undergoing shoulder arthroscopy, low-dose perineural dexamethasone (1 mg) in combination with 15 mL of 0.5% bupivacaine prolonged the median time until pain relief from the ISB completely wore off compared with 1 mg IV dexamethasone. However, the degree of prolongation was smaller than the a priori-defined minimal clinically meaningful difference of 5 hours. CLINICAL TRIAL REGISTRATION: This study was registered at Clinicaltrials.gov, identifier NCT02506660.

Effective Dose of Intravenous Dexmedetomidine to Prolong the Analgesic Duration of Interscalene Brachial Plexus Block: A Single-Center, Prospective, Double-Blind, Randomized Controlled Trial.

BACKGROUND AND OBJECTIVES: Intravenous (IV) dexmedetomidine (DEX) is reported to prolong the analgesic duration after single-shot interscalene brachial plexus block (ISBPB). However, the effective analgesic dose of IV DEX remains undetermined. Therefore, we aimed to elucidate the clinically relevant dose of IV DEX to prolong the analgesic duration of ISBPB. METHODS: Seventy-two patients scheduled for arthroscopic shoulder surgery received ISBPB with 15 mL of 0.5% ropivacaine with 1:200,000 epinephrine and were randomly assigned to 1 of 4 groups (n = 18, each): (1) IV normal saline (control), (2) IV DEX 0.5 µg/kg (DEX 0.5), (3) IV DEX 1.0 µg/kg (DEX 1.0), and (4) IV DEX 2.0 µg/kg (DEX 2.0). The primary outcome was time to the first pain at surgical site. RESULTS: The median (interquartile range) duration of analgesia was significantly prolonged for the DEX 2.0 (874 minutes [727-1153 minutes]) compared with 656 minutes (590-751 minutes), 703 minutes (644-761 minutes), and 696 minutes (615-814 minutes) for the control, DEX 0.5 and DEX 1.0 groups, respectively (P = 0.001, P = 0.008, and P = 0.003, respectively). Postoperative cumulative IV morphine equivalent consumption at 24 hours was significantly lower in the DEX 2.0 compared with the control, DEX 0.5 and DEX 1.0 groups (P < 0.001, P < 0.001, and P = 0.007, respectively). There were no significant differences in the incidence of intraoperative hypotension and the number of patients who required ephedrine after the pairwise group analysis. Also, there were no significant differences on the durations of motor blockade and sedation and the incidence of bradycardia. CONCLUSIONS: Intravenous DEX at a dose of 2.0 µg/kg significantly increased the duration of ISBPB analgesia without prolonging motor blockade and reduced the cumulative opioid consumption at the first 24 hours in patients undergoing arthroscopic shoulder surgery. CLINICAL TRIAL REGISTRATION: This study was registered at the Clinical Trial Registry of Korea, identifier KCT0002119.

Selective Suprascapular and Axillary Nerve Block Versus Interscalene Plexus Block for Pain Control After Arthroscopic Shoulder Surgery: A Noninferiority Randomized Parallel-Controlled Clinical Trial.

BACKGROUND AND OBJECTIVES: This randomized trial aimed to assess if a combined suprascapular-axillary nerve block (SSB) is noninferior (margin = 1.3 on a 0- to 10-point scale) to interscalene block (ISB) in treating pain after arthroscopic shoulder surgery. Secondary end points included opioid consumption, dyspnea, discomfort associated with muscle weakness, and patient satisfaction. METHODS: One hundred patients undergoing arthroscopic shoulder surgery were randomized to receive ultrasound-guided ISB (n = 50) or SSB (n = 50). Pain intensity at rest, dyspnea, and discomfort were recorded upon arrival in the recovery room, discharge to the ward, and at 4, 8, and 24 hours after surgery. Piritramide consumption was recorded for the first 24 hours. Patient satisfaction was assessed on the second postoperative day. RESULTS: During the first 4 hours after surgery, the difference in mean pain score between SSB and ISB was higher than 2.5 (±0.8). The difference gradually decreased to 1.1 (±1.0) at 8 hours before resulting in noninferiority during the night and at 24 hours. Piritramide consumption was significantly higher in the SSB group in the first 8 hours. The incidence of dyspnea and discomfort was higher after ISB. Treatment satisfaction was similar in both groups. CONCLUSIONS: Suprascapular-axillary nerve block is inferior to ISB in terms of analgesia and opioid requirement in the immediate period after arthroscopic shoulder surgery but is associated with a lower incidence of dyspnea and discomfort. The difference in pain and opioid consumption gradually decreases as the blocks wear off in order to reach similar pain scores during the first postoperative night and at 24 hours. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02415088.

Optimal Dose of Perineural Dexamethasone to Prolong Analgesia After Brachial Plexus Blockade: A Systematic Review and Meta-analysis.

BACKGROUND: Perineural dexamethasone has gained popularity in regional anesthesia to prolong analgesia duration. However, uncertainty remains regarding the optimal perineural dose. Clarification of this characteristic is of significant importance as the administration of dexamethasone may lead to dose-dependent complications. The objective of this meta-analysis was to define the optimal perineural dexamethasone dose to prolong analgesia after brachial plexus blockade for adult patients undergoing upper limb surgery. METHODS: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines and searched databases including MEDLINE, PubMed, and EMBASE until January 2017, without language restriction. Only trials comparing perineural dexamethasone and local anesthetics with local anesthetics alone for brachial plexus blocks were included in the present meta-analysis. The Cochrane Collaboration's Risk of Bias Tool was used to assess the methodological quality of each trial and meta-analyses were performed following a random effects model. The primary outcome was duration of analgesia for each type of local anesthetic (short-/intermediate-acting and long-acting local anesthetics). A meta-regression followed by a subgroup analysis were performed to assess the impact of different perineural dexamethasone doses on duration of analgesia; for the latter analysis, trials were grouped in low (1-4 mg) and moderate (5-10 mg) dexamethasone doses. Secondary outcomes included the rate of neurologic complication and resting pain scores and morphine consumption within the first 24 hours. RESULTS: Thirty-three controlled trials, including 2138 patients, were identified. The meta-regression revealed a ceiling effect with a perineural dexamethasone dose of 4 mg when combined with short-/intermediate-acting (8 trials; 366 participants) or long-acting local anesthetics (23 trials; 1869 participants). This finding was confirmed by subgroup analyses comparing low and moderate dexamethasone doses. With short-/intermediate-acting local anesthetics, the mean difference (95% confidence interval) of analgesia duration with low and moderate doses was 277 (234-322) minutes and 229 (161-297) minutes, respectively. With long-acting local anesthetics, the mean differences with low and moderate doses were 505 (342-669) minutes and 509 (443-575) minutes. Perineural dexamethasone did not increase the rate of neurologic complications (risk ratio [95% confidence interval], 1.40 [0.54-3.63]). The Grades of Recommendation, Assessment, Development, and Evaluation quality of evidence for the primary and secondary outcomes were very low, due mainly to limitations, inconsistency, indirectness, and publication bias. CONCLUSIONS: There is currently very low quality evidence that 4 mg of perineural dexamethasone represents a ceiling dose that prolongs analgesia duration by a mean period of 6 and 8 hours when combined with short-/intermediate- or long-acting local anesthetics, respectively. Additional data are needed to explore the threshold for this effect, particularly with doses below 4 mg. The risk of neurologic complications is probably not increased (very low evidence).

A Retrospective Study Evaluating the Effect of Low Doses of Perineural Dexamethasone on Ropivacaine Brachial Plexus Peripheral Nerve Block Analgesic Duration.

Objective: Examination of the effectiveness of perineural dexamethasone administered in very low and low doses on ropivacaine brachial plexus block duration. Design: Retrospective evaluation of brachial plexus block duration in a large cohort of patients receiving peripheral nerve blocks with and without perineural dexamethasone in a prospectively collected quality assurance database. Setting: A single academic medical center. Methods: A total of 1,942 brachial plexus blocks placed over a 16-month period were reviewed. Demographics, nerve block location, and perineural dexamethasone utilization and dose were examined in relation to block duration. Perineural dexamethasone was examined as none (0 mg), very low dose (2 mg or less), and low dose (greater than 2 mg to 4 mg). Continuous catheter techniques, local anesthetics other than ropivacaine, and block locations with fewer than 15 subjects were excluded. Associations between block duration and predictors of interest were examined using multivariable regression models. A subgroup analysis of the impact of receiving dexamethasone on block duration within each block type was also conducted using a univariate linear regression approach. Results: A total of 1,027 subjects were evaluated. More than 90% of brachial plexus blocks contained perineural dexamethasone (≤4 mg), with a median dose of 2 mg. Increased block duration was associated with receiving any dose of perineural dexamethasone (P < 0.0001), female gender (P = 0.022), increased age (P = 0.048), and increased local anesthetic dose (P = 0.01). In a multivariable model, block duration did not differ with very low- or low-dose perineural dexamethasone after controlling for other factors (P = 0.420). Conclusion: Perineural dexamethasone prolonged block duration compared with ropivacaine alone; however, duration was not greater with low-dose compared with very low-dose perineural dexamethasone.

IV and Perineural Dexmedetomidine Similarly Prolong the Duration of Analgesia after Interscalene Brachial Plexus Block: A Randomized, Three-arm, Triple-masked, Placebo-controlled Trial.

BACKGROUND: Perineural and IV dexmedetomidine have each been suggested to prolong the duration of analgesia when administered in conjunction with peripheral nerve blocks. In the first randomized, triple-masked, placebo-controlled trial to date, the authors aimed to define and compare the efficacy of perineural and IV dexmedetomidine in prolonging the analgesic duration of single-injection interscalene brachial plexus block (ISB) for outpatient shoulder surgery. METHODS: Ninety-nine patients were randomized to receive ISB using 15 ml ropivacaine, 0.5%, with 0.5 µg/kg dexmedetomidine administered perineurally (DexP group), intravenously (DexIV group), or none (control group). The authors sequentially tested the joint hypothesis that dexmedetomidine prolongs the duration of analgesia and reduces the 24-h cumulative postoperative morphine consumption. Motor blockade, pain severity, hemodynamic variations, opioid-related side effects, postoperative neurologic symptoms, and patient satisfaction were also evaluated. RESULTS: Ninety-nine patients were analyzed. The duration of analgesia was 10.9 h (10.0 to 11.8 h) and 9.8 h (9.0 to 10.6 h) for the DexP and DexIV groups, respectively, compared with 6.7 h (5.6 to 7.8) for the control group (P < 0.001). Dexmedetomidine also reduced the 24-h cumulative morphine consumption to 63.9 mg (58.8 to 69.0 mg) and 66.2 mg (60.6 to 71.8 mg) for the DexP and DexIV groups, respectively, compared with 81.9 mg (75.0 to 88.9 mg) for the control group (P < 0.001). DexIV was noninferior to DexP for these outcomes. Both dexmedetomidine routes reduced the pain and opioid consumption up to 8 h postoperatively and did not prolong the duration of motor blockade. CONCLUSION: Both perineural and IV dexmedetomidine can effectively prolong the ISB analgesic duration and reduce the opioid consumption without prolonging motor blockade.

Changes in heart rate variability after sitting following interscalene block.

PURPOSE: Hypotensive bradycardic events (HBEs) occur in 5-28% of patients undergoing arthroscopic shoulder surgery in the sitting position after an interscalene brachial plexus block (ISBPB). The objective of this study was to investigate the effects of the sitting position following ISBPB on heart rate variability (HRV). METHODS: In this prospective case-control study, we evaluated 64 patients undergoing arthroscopic shoulder surgery under ISBPB and 49 nonsurgical control subjects. HRV power spectral analysis parameters were measured (and natural log-transformed) before ISBPB and after changing to the sitting position. The patients experiencing HBEs were assigned to the HBE group, and the remaining patients were assigned to the non-HBE group. RESULTS: HBEs developed in 18 patients (28.1%). Changing from the supine position to the sitting position after ISBPB did not induce a significant increase in the natural log-transformed ratio of low-frequency to high-frequency power (lnLF/HF). A significant decrease in natural log-transformed high-frequency power (lnHF) was observed compared to the control group, who presented a significant increase in lnLF/HF and an insignificant change in lnHF. lnHF was found to be significantly higher in the HBE group compared to the non-HBE group. CONCLUSIONS: Sustained vagal activity with a failed shift in the sympathovagal balance toward sympathetic predominance in response to sitting after ISBPB is associated with the development of HBE.