Analgesic benefits of regional anesthesia in the perioperative management of transition-related surgery: a systematic review.

INTRODUCTION: Transition-related surgery is an effective treatment for gender dysphoria, but the perioperative analgesic management of transgender patients is nuanced and potentially complicated by higher rates of mood and substance use disorders. Regional anesthetic techniques are known to reduce pain severity and opioid requirements; however, little is known regarding the relative analgesic effectiveness of regional anesthesia for transgender patients undergoing transition-related surgery. METHODS: We performed a systematic review of the literature to evaluate original reports characterizing the analgesic effectiveness of regional anesthetic techniques for patients undergoing chest and/or genital transition-related surgery. Our primary outcomes were pain severity and opioid requirements on the first postoperative day. RESULTS: Of the 1863 records identified, 10 met criteria for inclusion and narrative synthesis. These included two randomized controlled trials, three cohort studies, and five case reports/series, comprising 293 patients. Four reports described 243 patients undergoing chest surgery, of whom 86% were transgender men undergoing mastectomy with pectoralis nerve blocks or local anesthetic instillation devices. The remaining six reports comprised 50 patients undergoing genital surgery, of whom 56% were transgender women undergoing vaginoplasty with erector spinae plane blocks or epidural anesthesia. Three studies directly compared regional techniques to parenteral analgesia alone. Two of these studies reported lower pain scores and opioid requirements on the first postoperative day with nerve blocks compared with none while the third study reported no difference between groups. Complications related to regional anesthetic techniques were rare among patients undergoing transition-related surgery. DISCUSSION: Despite the ever-growing demand for transition-related surgery, the relative analgesic effectiveness of regional anesthesia for transgender patients undergoing transition-related surgery is very understudied and insufficient to guide clinical practice. Our systematic review of the literature serves to underscore regional anesthesia for transition-related surgery as a priority area for future research.

The analgesic effectiveness of perioperative lidocaine infusions for acute and chronic persistent postsurgical pain in patients undergoing breast cancer surgery: a systematic review and meta-analysis.

BACKGROUND: Breast cancer is the most common cancer among women and tumour resection carries a high prevalence of chronic persistent postsurgical pain (CPSP). Perioperative i.v. lidocaine infusion has been proposed as protective against CPSP; however, evidence of its benefits is conflicting. This review evaluates the effectiveness of perioperative lidocaine infusions for breast cancer surgery. METHODS: Randomised trials comparing perioperative lidocaine infusions with parenteral analgesia in breast cancer surgery patients were sought. The two co-primary outcomes were the odds of CPSP at 3 and 6 months after operation. Secondary outcomes included rest pain at 1, 6, 12, and 24 h; analgesic consumption at 0-24 and 25-48 h; quality of recovery; opioid-related side-effects; and lidocaine infusion side-effects. Hartung-Knapp-Sidik-Jonkman (HKSJ) random effects modelling was used. RESULTS: Thirteen trials (1039 patients; lidocaine: 518, control: 521) were included. Compared with control, perioperative lidocaine infusion did not decrease the odds of developing CPSP at 3 and 6 months. Lidocaine infusion improved postoperative pain at 1 h by a mean difference (95% confidence interval) of -0.65 cm (-0.73 to -0.57 cm) (P<0.0001); however, this difference was not clinically important (1.1 cm threshold). Similarly, lidocaine infusion reduced oral morphine consumption by 7.06 mg (-13.19 to -0.93) (P=0.029) over the first 24 h only; however, this difference was not clinically important (30 mg threshold). The groups were not different for any of the remaining outcomes. CONCLUSIONS: Our results provide moderate-quality evidence that perioperative lidocaine infusion does not reduce CPSP in patients undergoing breast cancer surgery. Routine use of lidocaine infusions for perioperative analgesia and CPSP prevention is not supported in this population. SYSTEMATIC REVIEW PROTOCOL: PROSPERO CRD42023420888.

Association between perioperative neuraxial local anesthetic neurotoxicity and arachnoiditis: a narrative review of published reports.

BACKGROUND/IMPORTANCE: Arachnoiditis is a rare but devastating disorder caused by various insults, one of which is purported to be local anesthetic neurotoxicity following neuraxial blockade. However, the relationship between local anesthetics administered into the neuraxis and the development of arachnoiditis has not been clearly elucidated. OBJECTIVE: We aimed to summarize the existing complex body of literature and characterize both the essential features and strength of any association between neuraxial local anesthetic neurotoxicity and arachnoiditis with a view toward mitigating risk, enhancing prevention, and refining informed consent discussions. EVIDENCE REVIEW: We reviewed all published reports of arachnoiditis attributed to local anesthetic neurotoxicity following perioperative neuraxial anesthesia. This narrative review was based on a systematic search methodology, which included articles published up until December 2022. FINDINGS: Thirty-eight articles were included, comprising 130 patients, over one-half of which were published prior to this century and inconsistent with modern practice. Neuraxial techniques included 78 epidurals, 48 spinals, and 5 combined spinal-epidurals, mostly for obstetrics. Reporting of essential procedural data was generally incomplete. Overall, at least 57% of patients experienced complicated needle/catheter insertion, including paresthesia, pain, or multiple attempts, irrespective of technique. The onset of neurological symptoms ranged from immediate to 8 years after neuraxial blockade, while the pathophysiology of arachnoiditis, if described, was heterogeneous. CONCLUSIONS: The existing literature attributing arachnoiditis to local anesthetic neurotoxicity is largely outdated, incomplete, and/or confounded by other potential causes, and thus insufficient to characterize the features and strength of any association.

Analgesic Effectiveness of Motor-sparing Nerve Blocks for Total Knee Arthroplasty: A Network Meta-analysis.

BACKGROUND: The analgesic effectiveness of contemporary motor-sparing nerve blocks used in combination for analgesia in total knee arthroplasty is unclear. This network meta-analysis was conducted to evaluate the analgesic effectiveness of adding single-injection or continuous adductor canal block (ACB) with or without infiltration of the interspace between the popliteal artery and the capsule of the posterior knee (iPACK) to intraoperative local infiltration analgesia (LIA), compared to LIA alone, after total knee arthroplasty. METHODS: Randomized trials examining the addition of single-injection or continuous ACB with or without single-injection block at the iPACK to LIA for total knee arthroplasty were considered. The two primary outcomes were area-under-the-curve pain scores over 24 to 48 h and postoperative function at greater than 24 h. Secondary outcomes included rest pain scores at 0, 6, 12, and 24 h; opioid consumption (from 0 to 24 h and from 25 to 48 h); and incidence of nausea/vomiting. Network meta-analysis was conducted using a frequentist approach. RESULTS: A total of 27 studies (2,317 patients) investigating the addition of (1) single-injection ACB, (2) continuous ACB, (3) single-injection ACB and single-injection block at the iPACK, and (4) continuous ACB and single-injection block at the iPACK to LIA, as compared to LIA alone, were included. For area-under-the-curve 24- to 48-h pain, the addition of continuous ACB with single-injection block at the iPACK displayed the highest P-score probability (89%) of being most effective for pain control. The addition of continuous ACB without single-injection block at the iPACK displayed the highest P-score probability (87%) of being most effective for postoperative function. CONCLUSIONS: The results suggest that continuous ACB, but not single-injection ACB and/or single-injection block at the iPACK, provides statistically superior analgesia when added to LIA for total knee arthroplasty compared to LIA alone. However, the magnitude of these additional analgesic benefits is clinically questionable.

Impact of outpatient total hip or knee replacement on informal caregivers at home: a scoping review.

BACKGROUND: Although total hip arthroplasty (THA) and total knee arthroplasty (TKA) offer significant cost savings to our health care system, the degree to which the burden of postoperative care has been transferred onto the informal caregiver is often overlooked. We performed a scoping review to identify the characteristics and factors that contribute to the burden of care experienced after outpatient THA and TKA. METHODS: We systematically searched electronic literature databases according to scoping review guidelines from inception to June 2021 for articles reporting the experiences of informal caregivers providing care for patients having undergone outpatient THA or TKA. Our review included English-language studies that sought to elucidate the impact on caregivers in the acute postoperative period (up to 6 wk after surgery). RESULTS: Our search yielded 1423 unique articles, which were screened for inclusion. We removed 310 duplicate records and excluded another 1099 articles because they did not meet the inclusion criteria for full-text screening with relevancy. We thus assessed 14 articles for full-text review, and none were found to meet our inclusion criteria. CONCLUSION: We found no published data pertaining to the burden borne by informal caregivers who provide perioperative care to patients who have undergone ambulatory THA or TKA. Further research is needed to identify, quantify and determine the modifiability of the various characteristics and factors that contribute to caregiver burden in the outpatient setting.

Evaluating the impact of cannabinoids on sleep health and pain in patients with chronic neuropathic pain: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Chronic neuropathic pain is often debilitating and can have a significant impact on sleep health and quality of life. There is limited information on the impact of cannabinoids on sleep health when treating neuropathic pain. OBJECTIVE: The objectives of this systematic review and meta-analysis were to determine the effect of cannabinoids on sleep quality, pain intensity, and patient impression of treatment efficacy in patients with neuropathic pain. EVIDENCE REVIEW: Nine available medical literature databases were searched for randomized controlled trials comparing synthetic and natural cannabinoids to placebo in patients with neuropathic pain syndromes. Data on validated tools for sleep quality, pain intensity, patients' global impression of change (PGIC), and incidence of adverse effects of cannabinoids were extracted and synthesized. FINDINGS: Of the 3491 studies screened, eight randomized controlled trials satisfied the inclusion criteria for this review. Analyses were performed using R -4.1.2. using the metafor package and are interpreted using alpha=0.05 as the threshold for statistical significance. Validated measures for sleep health were not used in most studies. Meta-analysis of data from six studies showed that cannabinoids were associated with a significant improvement in sleep quality (standardized mean difference (SMD): 0.40; 95% CI: 0.19 to -0.61, 95% prediction interval (PI): -0.12 to 0.88, p-value=0.002, I2=55.26, τ2=0.05, Q-statistic=16.72, GRADE: moderate certainty). Meta-analysis of data from eight studies showed a significant reduction in daily pain scores in the cannabinoid (CB) group (SMD: -0.55, 95% CI:-0.69 to -0.19, 95% PI: -1.51 to 0.39, p=0.003, I2=82.49, τ2=0.20, Q-statistic=47.69, GRADE: moderate certainty). However, sleep health and analgesic benefits were associated with a higher likelihood of experiencing daytime somnolence, nausea, and dizziness. CONCLUSIONS: Cannabinoids have a role in treating chronic neuropathic pain as evidenced by significant improvements in sleep quality, pain intensity, and PGIC. More research is needed to comprehensively evaluate the impact of cannabinoids on sleep health and analgesic efficacy. PROSPERO REGISTRATION NUMBER: CRD42017074255.

Analgesic benefits of single-shot versus continuous adductor canal block for total knee arthroplasty: a systemic review and meta-analysis of randomized trials.

BACKGROUND: Adductor canal block (ACB) can provide important analgesic benefits following total knee arthroplasty (TKA), however, the extent to which these benefits can be enhanced or prolonged by a continuous catheter-based infusion compared with a single-shot injection of local anesthetic is unclear. OBJECTIVES: This systematic review and meta-analysis (PROSPERO: CRD42021292738) review sought to compare the analgesic effectiveness of single shot to continuous ACB following TKA. EVIDENCE REVIEW: We sought randomized trials from the US National Library of Medicine database (MEDLINE), Excerpta Medica database (EMBASE), and Cochrane Database of Systematic Reviews from inception to November 1, 2021, that compared single-shot to continuous ACB in adult patients undergoing TKA. The primary outcomes were (1) area under the curve (AUC) pain severity at rest and (2) cumulative opioid (oral morphine equivalent) consumption during the first 48 hours postoperatively. Secondary outcomes included postoperative pain severity scores up to 48 hours, cumulative opioid consumption at 24 hours, functional recovery, opioid-related side effects, and block-related complications. Risk of bias of included studies was assessed using the Cochrane risk of bias tool. Statistical pooling was conducted using the Hartung-Knapp-Sidik-Jonkman method for random effects. No funding was obtained for this review. FINDINGS: Eleven trials (1185 patients) were included. No differences were observed in rest pain severity (AUC) or cumulative opioid consumption up to 48 hours postoperatively. In addition, no differences were observed in individual postoperative rest pain scores in the recovery room and at 12 and 24 hours, or in cumulative opioid consumption at 24 hours, functional recovery, and opioid-related side effects. Finally, fewer block-related complications were observed with single-shot ACB, with an OR (95% CI) of 0.24 (0.14 to 0.41) (p=0.002). CONCLUSIONS: Our results suggest that continuous catheter-based ACB does not enhance or prolong the analgesic benefits when compared with single-shot ACB for TKA over the first 48 hours postoperatively. Overall, the results of our meta-analysis do not support the routine use of continuous ACB for postoperative analgesia after TKA.

The role of hyperbaric oxygen therapy in the management of perioperative peripheral nerve injury: a scoping review of the literature.

BACKGROUND/IMPORTANCE: Peripheral nerve injury is an uncommon but potentially catastrophic complication of anesthesia and surgery, for which there are limited effective treatment options. Hyperbaric oxygen therapy is a unique medical intervention which improves tissue oxygen delivery and reduces ischemia via exposure to oxygen at supra-atmospheric partial pressures. While the application of hyperbaric oxygen therapy has been evidenced for other medical conditions involving relative tissue ischemia, its role in the management of peripheral nerve injury remains unclear. OBJECTIVE: This scoping review seeks to characterize rehabilitative outcomes when hyperbaric oxygen therapy is applied as an adjunct therapy in the treatment of perioperative peripheral nerve injury. EVIDENCE REVIEW: The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping reviews, using a systematic screening and extraction process. The search included articles published from database inception until June 11, 2022, which reported clinical outcomes (in both human and non-human models) of peripheral nerve injury treated with hyperbaric oxygen therapy. FINDINGS: A total of 51 studies were included in the narrative synthesis. These consisted of animal (40) and human studies (11) treating peripheral nerve injury due to various physiological insults. Hyperbaric oxygen therapy protocols were highly heterogenous and applied at both early and late intervals relative to the time of peripheral nerve injury. Overall, hyperbaric oxygen therapy was reported as beneficial in 88% (45/51) of included studies (82% of human studies and 90% of animal studies), improving nerve regeneration and/or time to recovery with no reported major adverse events. CONCLUSIONS: Existing data suggest that hyperbaric oxygen therapy is a promising intervention in the management of perioperative peripheral nerve injury, in which tissue ischemia is the most common underlying mechanism of injury, neurological deficits are severe, and treatment options are sparse. This positive signal should be further investigated in prospective randomized clinical trials.

What Is the Risk of Postoperative Neurologic Symptoms After Regional Anesthesia in Upper Extremity Surgery? A Systematic Review and Meta-analysis of Randomized Trials.

BACKGROUND: The risk of neurologic symptoms after regional anesthesia in orthopaedic surgery is estimated to approach 3%, with long-term deficits affecting 2 to 4 per 10,000 patients. However, current estimates are derived from large retrospective or observational studies that are subject to important systemic biases. Therefore, to harness the highest quality data and overcome the challenge of small numbers of participants in individual randomized trials, we undertook this systematic review and meta-analysis of contemporary randomized trials. QUESTIONS/PURPOSES: In this systematic review and meta-analysis of randomized trials we asked: (1) What is the aggregate pessimistic and optimistic risk of postoperative neurologic symptoms after regional anesthesia in upper extremity surgery? (2) What block locations have the highest and lowest risk of postoperative neurologic symptoms? (3) What is the timing of occurrence of postoperative neurologic symptoms (in days) after surgery? METHODS: We searched Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews, Web of Science, Scopus, and PubMed for randomized controlled trials (RCTs) published between 2008 and 2019 that prospectively evaluated postoperative neurologic symptoms after peripheral nerve blocks in operative procedures. Based on the Grading of Recommendations, Assessment, Development, and Evaluation guidance for using the Risk of Bias in Non-Randomized Studies of Interventions tool, most trials registered a global rating of a low-to-intermediate risk of bias. A total of 12,532 participants in 143 trials were analyzed. Data were pooled and interpreted using two approaches to calculate the aggregate risk of postoperative neurologic symptoms: first according to the occurrence of each neurologic symptom, such that all reported symptoms were considered mutually exclusive (pessimistic estimate), and second according to the occurrence of any neurologic symptom for each participant, such that all reported symptoms were considered mutually inclusive (optimistic estimate). RESULTS: At any time postoperatively, the aggregate pessimistic and optimistic risks of postoperative neurologic symptoms were 7% (915 of 12,532 [95% CI 7% to 8%]) and 6% (775 of 12,532 [95% CI 6% to 7%]), respectively. Interscalene block was associated with the highest risk (13% [661 of 5101] [95% CI 12% to 14%]) and axillary block the lowest (3% [88 of 3026] [95% CI 2% to 4%]). Of all symptom occurrences, 73% (724 of 998) were reported between 0 and 7 days, 24% (243 of 998) between 7 and 90 days, and 3% (30 of 998) between 90 and 180 days. Among the 31 occurrences reported at 90 days or beyond, all involved sensory deficits and four involved motor deficits, three of which ultimately resolved. CONCLUSION: When assessed prospectively in randomized trials, the aggregate risk of postoperative neurologic symptoms associated with peripheral nerve block in upper extremity surgery was approximately 7%, which is greater than previous estimates described in large retrospective and observational trials. Most occurrences were reported within the first week and were associated with an interscalene block. Few occurrences were reported after 90 days, and they primarily involved sensory deficits. Although these findings cannot inform causation, they can help inform risk discussions and clinical decisions, as well as bolster our understanding of the evolution of postoperative neurologic symptoms after regional anesthesia in upper extremity surgery. Future prospective trials examining the risks of neurologic symptoms should aim to standardize descriptions of symptoms, timing of evaluation, classification of severity, and diagnostic methods. LEVEL OF EVIDENCE: Level I, therapeutic study.

The analgesic benefit of Pericapsular Nerve Group (PENG) block in hip arthroscopic surgery: a retrospective pragmatic analysis at an academic health center.

INTRODUCTION: The novel pericapsular nerve group (PENG) block has recently been reported to provide effective motor-sparing local anesthetic-based analgesia to the hip joint. We aimed to evaluate the analgesic efficacy and safety of a preoperative PENG block among patients undergoing ambulatory hip arthroscopic surgery where systemic analgesia is the gold standard. METHODS: We conducted a single-center, retrospective pragmatic exploratory cohort study of consecutive outpatient hip arthroscopic surgery cases from January 2017 to March 2019. We identified 164 cases in which patients received general anesthesia with or without a preoperative PENG block. The primary analgesic outcome measures were time to first postoperative analgesic request, intraoperative and postoperative opioid consumption (intravenous morphine equivalent), and postoperative pain severity (visual analog scale 10 cm scale ranging from 0=no pain to 10=severe pain) in hospital. Secondary outcomes included duration of stay in the postanesthesia care unit, opioid-related side effects, time to discharge readiness, and block-related complications. RESULTS: Seventy-five cases received a preoperative PENG block and 89 cases received systemic analgesia alone. The addition of a PENG block reduced intraoperative (6.6 mg vs 7.5 mg, difference: 0.9 mg; 95% CI 0.2 to 1.7; p=0.01) and postoperative (10.7 mg vs 13.9 mg, difference: 3.2 mg; 95% CI 0.9 to 5.5; p=0.01) intravenous morphine consumption, as well as the mean (3.5 vs 4.2, difference: 0.7; 95% CI 0.1 to 1.3; p=0.03) and highest (5.5 vs 6.5, difference: 1.0; 95% CI 0.2 to 1.7; p=0.02) postoperative pain severity scores in hospital. The PENG block did not prolong the time to first analgesic request (15.8 min vs 12.3 min, difference: 3.5 min; 95% CI -9.0 to 2.0; p=0.23). Fewer patients in the PENG group experienced postoperative nausea and vomiting compared with systemic analgesia alone (36% vs 52%, OR 1.9; 95% CI 1.0 to 3.6; p=0.02), while the PENG block expedited discharge readiness (165.0 min vs 202.8 min, difference: 37.8 min; 95% CI 2.9 to 72.3; p=0.04). No block-related complications were noted in any patient. DISCUSSION: Based on our retrospective dataset, this pragmatic exploratory cohort study suggests that a preoperative PENG block is associated with questionable improvements in postoperative in-hospital analgesic outcomes which may or may not prove to be clinically relevant when compared with systemic analgesia alone for patients undergoing hip arthroscopic surgery. This small signal should be investigated in a prospective randomized trial.

Prospective preference assessment for the Comparison of Analgesic Regimen Effectiveness and Safety in Surgery (CARES) trial.

BACKGROUND: Clinical trials face major barriers such as under-enrollment and selective enrollment, which threaten study completion and undermine validity and generalizability. Thus, we conducted a prospective preference assessment (PPA) prior to commencing the Comparison of Analgesic Regimen Effectiveness and Safety in Surgery (CARES) trial-a randomized controlled study comparing the outcomes of managing acute postoperative pain between opioid-sparing and opioid-based therapies. This PPA aimed to (1) determine the patients' willingness to participate in the CARES trial, (2) identify the areas for improvement, and (3) assess the differences between willing and unwilling patients. METHODS: Patients undergoing elective laparoscopic cholecystectomy were recruited between August 2019 and February 2020 from two academic hospitals. A survey was administered to each patient consisting of (1) a vignette describing the trial, (2) an assessment of the patients' understanding of the trial, (3) open-ended questions assessing the attitudes towards the trial, and (4) patient-completed questionnaires. Data were analyzed qualitatively with thematic analysis and quantitatively with the Wilcoxon signed-rank and chi-square tests. RESULTS: Forty-two patients were enrolled and grouped based on the 6-point Likert scale into willing (4-6, 71%) and not willing (1-3, 29%) to participate in the CARES trial. There were no significant differences with respect to all variables: age, education, sex, visible minority status, previous research, previous surgery, regular use of pain medications, surgical concerns, previous discussions on pain management, significant pain within the past 3 months, and significant use of pain medication within the past month. Factors that motivated participation were contributing to scientific research (45%), altruism (29%), and improving personal pain (24%). Common discouraging factors were negative perceptions of opioids (29%), side effects (21%), being blinded to the study medication (21%), and poor pain management (19%). CONCLUSIONS: This PPA revealed that two key discouraging factors for patients were being blinded to the type of pain medication being taken and the potential for poor pain management as a consequence of participation. Modifications to improve patient acceptance of the CARES trial include ensuring sufficient rescue medicine and follow-up visits consistent with current standards of care for all patients, as well as patient education surrounding safe administration and side effects of the study medications.

Analgesic effect of perineural local anesthetics, steroids, and conventional medical management for trauma and compression-related peripheral neuropathic pain: a retrospective cohort study.

INTRODUCTION: Trauma and compression are common causes of peripheral neuropathic pain (NP) refractory to conventional medical management (CMM). The role of perineural interventions in relieving this type of pain is unclear. OBJECTIVES: The objectives of this retrospective study were to determine the analgesic benefits of adding a combination of perineural local anesthetic and steroids (LA-S) to CMM compared with CMM alone in patients who had moderate-to-severe refractory NP after trauma to the ankle and the foot. METHODS: Health care records of 60 patients in exposed (3 injections of perineural LA-S at weekly intervals with CMM) and 60 in unexposed (CMM) cohorts were reviewed. Data on patient characteristics, pain, and mental and physical function were extracted at baseline and at the postintervention follow-up. Data were analyzed to evaluate analgesic benefit from the study interventions and the impact of baseline characteristics. RESULTS: Perineural LA-S with CMM cohort had lower pain numerical rating scale scores at 1 to 3 months after the intervention as compared to the CMM alone cohort (5.50 [interquartile range 4.00-7.00] and 7.00 [interquartile range 5.00-8.00], respectively; P < 0.01). However, multivariable analysis did not show an independent beneficial analgesic effect with the addition of perineural LA-S to CMM compared with CMM alone. A greater severity of preintervention catastrophizing (each unit increase in pain catastrophizing score increased pain score at follow-up by 0.04, 95% confidence interval: 0.01-0.07) was associated with reduction in the analgesic benefit. CONCLUSION: Perineural local anesthetic and steroid injections do not confer an analgesic benefit for trauma- or compression-related peripheral NP.

Regional anesthesia and acute compartment syndrome: principles for practice.

Acute compartment syndrome (ACS) is a potentially reversible orthopedic surgical emergency leading to tissue ischemia and ultimately cell death. Diagnosis of ACS can be challenging, as neither clinical symptoms nor signs are sufficiently sensitive. The cardinal symptom associated with ACS is pain reported in excess of what would otherwise be expected for the underlying injury, and not reasonably managed by opioid-based analgesia. Regional anesthesia (RA) techniques are traditionally discouraged in clinical settings where the development of ACS is a concern as sensory and motor nerve blockade may mask symptoms and signs of ACS. This Education article addresses the most common trauma and elective orthopedic surgical procedures in adults with a view towards assessing their respective risk of ACS and offering suggestions regarding the suitability of RA for each type of surgery.

Efficacy of perineural versus intravenous dexmedetomidine as a peripheral nerve block adjunct: a systematic review.

BACKGROUND: Dexmedetomidine is an effective local anesthetic adjunct for peripheral nerve blocks. The intravenous route for administering dexmedetomidine has been suggested to be equally effective to the perineural route; but comparative evidence is conflicting. OBJECTIVES: This evidence-based review evaluated trials comparing the effects of intravenous to perineural dexmedetomidine on peripheral nerve block characteristics in adult surgical patients. Our primary aim was to evaluate the durations of sensory and motor blockade. Duration of analgesia, onset times of sensory and motor blockade, analgesic consumption, rest pain, and dexmedetomidine-related adverse events were evaluated as secondary outcomes. EVIDENCE REVIEW: We sought randomized trials comparing the effects of intravenous to perineural dexmedetomidine on peripheral nerve block characteristics. The Cochrane Risk of Bias tool and the Grades of Recommendation, Assessment, Development, and Evaluation criteria was used to evaluate the quality of evidence for when an outcome was reported by at least three studies. RESULTS: Ten studies compared intravenous and perineural dexmedetomidine in the setting of upper extremity blocks (seven), lower extremity blocks (two), and truncal block (one). The doses of dexmedetomidine supplementing long-acting local anesthetics varied between a predetermined dose (50 µg) and a weight-based dose (0.5 µg/kg-1.0 µg/kg). Clinical diversity precluded quantitative pooling; and evidence is presented as a systematic review. Compared with the intravenous route, moderate quality evidence found that perineural dexmedetomidine prolonged the duration of sensory blockade in four of six trials and motor blockade in five of seven trials. Perineural dexmedetomidine also hastened the onset of sensory and motor blockade in three of six trials. No differences were reported for the remaining outcomes; and intravenous dexmedetomidine was not superior for any outcome in any of the trials. CONCLUSIONS: Moderate quality evidence appears to suggest that intravenous dexmedetomidine is an inferior peripheral nerve block adjunct compared with perineural dexmedetomidine. Perineural dexmedetomidine is associated with longer durations and faster onset of sensory and motor blockade.

Does the addition of iPACK to adductor canal block in the presence or absence of periarticular local anesthetic infiltration improve analgesic and functional outcomes following total knee arthroplasty? A systematic review and meta-analysis.

BACKGROUND: When combined with adductor canal block (ACB), local anesthetic infiltration between popliteal artery and capsule of knee (iPACK) is purported to improve pain following total knee arthroplasty (TKA). However, the analgesic benefits of adding iPACK to ACB in the setting of surgeon-administered periarticular local infiltration analgesia (LIA) are unclear. OBJECTIVES: To evaluate the analgesic benefits of adding iPACK to ACB, compared with ACB alone, in the setting of LIA following TKA. EVIDENCE REVIEW: We conducted a meta-analysis of randomized trials comparing the effects of adding iPACK block to ACB versus ACB alone on pain severity at 6 hours postoperatively in adult patients undergoing TKA. We a priori planned to stratify analysis for use of LIA. Opioid consumption at 24 hours, functional recovery, and iPACK-related complications were secondary outcomes. FINDINGS: Fourteen trials (1044 patients) were analyzed. For the primary outcome comparison in the presence of LIA (four trials, 273 patients), adding iPACK to ACB did not improve postoperative pain at 6 hours. However, in the absence of LIA (eight trials, 631 patients), adding iPACK to ACB reduced pain by a weighted mean difference (WMD) (95% CI) of -1.33 cm (-1.57 to -1.09) (p<0.00001). For the secondary outcome comparisons in the presence of LIA, adding iPACK to ACB did not improve postoperative pain at all other time points, opioid consumption or functional recovery. In contrast, in the absence of LIA, adding iPACK to ACB reduced pain at 12 hours, and 24 hours by a WMD (95% CI) of -0.98 (-1.79 to -0.17) (p=0.02) and -0.69 (-1.18 to -0.20) (p=0.006), respectively, when compared with ACB alone, but did not reduce opioid consumption. Functional recovery was also improved by a log(odds ratio) (95% CI) of 1.28 (0.45 to 2.11) (p=0.003). No iPACK-related complications were reported. CONCLUSION: Adding iPACK to ACB in the setting of periarticular LIA does not improve analgesic outcomes following TKA. In the absence of LIA, adding iPACK to ACB reduces pain up to 24 hours and enhances functional recovery. Our findings do not support the addition of iPACK to ACB when LIA is routinely administered.