Richard Brull

Background Hip arthroscopy is an increasingly common outpatient surgical procedure where postoperative pain can be severe. Peripheral nerve blocks have been evaluated for analgesia following hip arthroscopy; however, there is no consensus on an optimal technique that provides effective local anesthetic-based postoperative analgesia without motor blockade. We hypothesized that the pericapsular nerve group (PENG) block would provide effective motor-sparing analgesia following ambulatory hip arthroscopy. Methods We conducted a randomized placebo-controlled double-blind trial comparing an ultrasound-guided PENG block with 20 mL of 0.5% ropivacaine to a control with a sham injection. Our primary outcomes were cumulative opioid consumption (oral morphine equivalent) and quality of recovery (QoR-15) scores at 24 hours postoperatively. Secondary outcomes included pain, postoperative opioid consumption, time to first analgesic request, postanesthesia care unit (PACU) length of stay, and opioid and block-related side effects. Results 94 patients were included (47 per group). QoR was similar between groups at 24 hours as measured by the QoR-15 (range 0–150, higher scores indicate better recovery): mean SD 96.8±20.9 in the PENG group versus 101.0±20.9 in the control group (mean difference −4.2; adjusted p=0.414). Opioid consumption at 24 hours was also similar between groups. In adjusted analyses, the PENG group required less opioid analgesia in the PACU (mean difference −9.5 MME; p=0.039) and had a shorter PACU stay (mean difference −20.5 min; p=0.027). Pain scores at rest and on movement decreased over time in both groups, with no consistent differences in overall pain trajectories. Opioid consumption at 48 hours, opioid-related adverse effects and block-related complications were similar between groups. Conclusions When administered preoperatively, the PENG block provides only modest early perioperative benefits without improving overall postoperative analgesia or QoR in patients undergoing ambulatory hip arthroscopy. Based on these findings, routine preoperative use of the PENG block for ambulatory hip arthroscopy cannot be recommended beyond standard multimodal analgesia, although it may be considered selectively to facilitate early PACU recovery in carefully chosen patients. The potential role of postoperative PENG block as a rescue intervention warrants further investigation. Trial registration number NCT03449680 ; https://clinicaltrials.gov/study/NCT03449680

Background: Despite its association with severe postoperative pain, the use of regional anesthesia techniques for penile-inversion vaginoplasty surgery is understudied. This retrospective study aimed to assess the analgesic effects of a saddle block (ultra-low dose hyperbaric spinal anesthesia) with intrathecal (IT) morphine in transgender females undergoing penile inversion vaginoplasty. Methods: We performed a single-centre, retrospective chart review of 72 patients who underwent penile-inversion vaginoplasty with or without saddle block with IT morphine at our institution over a 26-months period. All patients received standard multimodal intravenous analgesia, and the surgeon administered both a pudendal nerve block and a spermatic cord block as part of routine care. Our primary outcome was cumulative opioid consumption (oral morphine equivalent) at 24h postoperatively. Secondary outcomes included postoperative pain severity, duration of stay in the postoperative care unit and in-hospital, time to first opioid request and incidence of opioid- and block-related side effects. Results: 30 patients received a saddle block with IT morphine and 42 patients received standard analgesia. We found no statistical difference in cumulative opioid consumption at 24h postoperatively (control group: 17.7 mg [5.6, 30.8] vs intervention group 12.5 mg [7.5, 22.5] P: 0.249). The addition of a saddle block was associated with clinically and statistically significant improvements in short-term postoperative pain-related outcomes in the recovery room, including mean and maximum pain severity scores, time to first analgesic request, and duration of stay. While no difference in pain scores was detected at the 24-hour time point, mixed-effects modelling demonstrated lower pain trajectories over time among patients in the intervention group, suggesting a time-dependent benefit. However, the significant time-by-group interaction (p = 0.024) indicates that the difference in pain scores between groups decreased over time. We found no differences in the rates of nausea and vomiting between groups. No saddle block procedure-related complications were reported. Conclusion: This retrospective study suggests that despite no statistically significant difference in 24-hour opioid consumption, the addition of a saddle block with 100 mcg of IT morphine is associated with improved PACU pain scores, a longer time to first analgesic request, and a shorter PACU stay. These findings are hypothesis-generating and merit further investigation in a prospective double-blind randomized controlled trial.

Background: Despite the low-risk nature of participation in most clinical anesthesia trials, subject recruitment on the same day as surgery is often restricted due to the concerns of researchers and local research ethics boards that same-day consent may not afford adequate time and opportunity for patients to weigh and make decisions, as well as perceptions of patient vulnerability immediately prior to surgery that could impact the voluntary nature and the rigor of the informed consent process. However, specialties such as anesthesiology, critical care, interventional radiology, and emergency medicine have a varied pattern of practice and patient acquaintance that does not typically afford the luxury of time or, in many cases, advance consent for participation in research. Indeed, the initial encounter between anesthesiologists and patients undergoing elective procedures routinely occurs on the day of surgery. Concerns of coercion related to same-day consent for clinical anesthesia research trials have not been borne out in the literature, and represent a significant obstacle to clinical researchers, as well as to the patients who are denied opportunities for potential benefit through participation in research studies. Methods: We describe the protocol for a prospective randomized controlled trial examining the voluntariness of patient consent, solicited either in advance of surgery or on the same day, to participate in an anesthesia research study at Women’s College Hospital. One hundred fourteen patients scheduled to undergo ambulatory anterior cruciate ligament repair facilitated by general anesthesia with an adductor canal block will be randomized for recruitment either (a) in the pre-operative assessment clinic before the day of surgery or (b) on the day of surgery, to be approached for consent to participate in a fabricated research study of adjunct medications in adductor canal blocks. Regardless of allocation, patients in both groups will receive the same routine standard of care and will complete a post-operative questionnaire to signal perceptions of undue influence in the process of providing informed consent for the fabricated trial. Discussion: This study will inform trial design and practice guidelines surrounding the amount of time patients ought to be afforded in order to make durable decisions to participate (or not) in clinical research studies. This is expected to impact trial recruitment in a variety of clinical settings where researchers have only brief opportunities to interface with patients. Trial registration: The trial was registered prospectively on the Open Science Framework (OSF), registration #46twc, on 2023-Mar-17.

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.

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.

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 themetaforpackage 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.

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.

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.

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.