Methadone-based Multimodal Analgesia Provides the Best-in-class Acute Surgical Pain Control and Functional Outcomes With Lower Opioid Use Following Major Posterior Fusion Surgery in Adolescents With Idiopathic Scoliosis

Anesthesia and Pain Management for Scoliosis Surgery: A Narrative Review

STUDY DESIGN

This was a narrative review.

OBJECTIVE

The objective of this review was to summarize the current evidence and knowledge gaps regarding anesthesia and pain management for scoliosis surgery, including multimodal analgesia, and identify the best anesthetic approach to scoliosis surgery that ensures patient safety and pain relief even in the postoperative period, with minimal influence on SSEP monitoring.

SUMMARY OF BACKGROUND DATA

Spinal surgeries and fusions for scoliosis are associated with high pain levels. Inadequate analgesia can cause patient dissatisfaction, delay recovery, and increase the risk of chronic pain. Despite serious side effects, opioids are the mainstay of pain medication after scoliosis surgery. However, increasing emphasis on minimizing opioids and accelerating recovery has increased the adoption of multimodal analgesic therapy.

MATERIALS AND METHODS

The literature review was performed on standards of care, a pain management protocol, current therapeutic options, and innovative treatment options for patients undergoing scoliosis surgery. The literature was reviewed through 4 electronic databases: PubMed, Cochrane Library, Google Scholar, and Embase.

RESULTS

The initial search yielded 994 articles. Forty-seven relevant articles were selected based on relevance, recentness, search quality, and citations. Ten studies described the influence of different methods of anesthesia on neuromonitoring. Twenty-one researchers studied the effect of analgesics and coanalgesics on pain relief protocol. Nine studies treated regional anesthesia and its influence on pain management.

CONCLUSIONS

The most suitable anesthetic approach that does not disturb the neuromonitoring is obtained by combining total intravenous anesthesia (TIVA) with remifentanil and propofol with regional anesthesia, particularly erector spinae plane block (ESPB), as a part of a multimodal analgesia protocol.

LEVEL OF EVIDENCE

Level II.

Effect of intraoperative methadone in robot-assisted cystectomy on postoperative opioid requirements: A randomized clinical trial

BACKGROUND

Postoperative pain management is a challenge after robot-assisted cystectomy (RAC). Methadone has a long duration of action, and we therefore hypothesized that a single dose of intraoperative methadone would reduce postoperative opioid requirements and pain intensity in bladder cancer patients undergoing RAC.

METHODS

We conducted a blinded randomized controlled clinical trial from July 2020 to August 2023. Patients scheduled to undergo RAC because of bladder cancer were randomized to receive intraoperative methadone (0.15 mg/kg-1) or morphine (0.15 mg kg-1) 1 h before endotracheal extubation. The primary outcome was opioid requirements after 24 h. Secondary outcomes were opioid requirements after 3 h, pain intensity at rest and during coughing, postoperative nausea and vomiting (PONV), sedation, hypoxemia, hypoventilation, time spent in the post-anesthetic care unit, and patient satisfaction.

RESULTS

A total of 114 patients were randomized. Data from 99 patients (14 females, 85 males; mean age 69.8 ± 8.9 years) were available for analysis; 52 received methadone and 47 received morphine. Opioid consumption was similar between the methadone group and morphine group at 3 h (median, mg, 45 (IQR 30 to 75) vs. 45 (IQR 15 to 82.5) p = .97) and at 24 h (median, mg, 125 (IQR 75 to 198.5) versus 105 (IQR 72 to 157.5), p = .29). Pain intensity was significantly lower in the morphine group at 48 h compared with the methadone group. Patient satisfaction at 24 h was increased in the methadone group compared with the morphine group (median, (IQR), NRS; 9 (IQR 7 to 10) versus 7 (IQR 4 to 9), p = .020). There were no differences between treatment groups in terms of time spent in the post-anesthetic care unit and the occurrence of opioid-related side effects.

CONCLUSION

A single dose of intraoperative methadone does not reduce postoperative opioid requirements compared with a single dose of morphine in bladder cancer patients undergoing RAC.

The Influence of Anesthesia on Neuromonitoring During Scoliosis Surgery: A Systematic Review

BACKGROUND

Intraoperative neuromonitoring (IONM) is crucial for the safety of scoliosis surgery, providing real-time feedback on the spinal cord and nerve function, primarily through motor-evoked potentials (MEPs). The choice of anesthesia plays a crucial role in influencing the quality and reliability of these neuromonitoring signals. This systematic review evaluates how different anesthetic techniques-total intravenous anesthesia (TIVA), volatile anesthetics, and regional anesthesia approaches such as Erector Spinae Plane Block (ESPB), spinal, and epidural anesthesia-affect IONM during scoliosis surgery.

METHODS

A systematic review was conducted following PRISMA guidelines. PubMed, MEDLINE, EMBASE, and Cochrane databases were searched for studies published between 2017 and 2024 that examined the impact of anesthetic techniques on neuromonitoring during scoliosis surgery. The focus was on studies reporting MEP outcomes, anesthetic protocols, and postoperative neurological and analgesic effects.

RESULTS

The search initially identified 998 articles. After applying inclusion criteria based on relevance, recency, methodological quality, and citation frequency, 45 studies were selected for detailed review.

CONCLUSION

The erector Spinae Plane Block (ESPB) provides distinct benefits over spinal and epidural anesthesia in scoliosis surgery, particularly in maintaining neuromonitoring accuracy, reducing hemodynamic instability, and minimizing complications. The ESPB's ability to deliver effective segmental analgesia without compromising motor function makes it a safer and more efficient option for postoperative pain management, enhancing patient outcomes.

High inpatient-opioid consumption predicts extended length of hospital stay in patients undergoing spinal fusion for adolescent idiopathic scoliosis

OBJECTIVES

Opioids are common medications used following spine surgery. However, few studies have assessed the impact of increased inpatient-opioid consumption on outcomes following posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS). The aim of this study was to determine the impact of increased inpatient-opioid consumption on hospital length of stay (LOS) following PSF for AIS.

METHODS

A retrospective cohort study was performed using the Premier Healthcare Database (2016-2017). Adolescent patients (11-17 years old) who underwent PSF for AIS, identified using ICD-10-CM coding, were stratified by inpatient MME (morphine milligram equivalent) consumption into Low (< 25th percentile for the cohort), Medium (25-75th percentile), and High (> 75th percentile) cohorts. Demographics, comorbidities, intraoperative procedures, perioperative adverse events (AEs), length of hospital stay (LOS), non-routine discharge rates, cost of admission, and 30-day readmission rates were assessed. A logistic multivariate regression analysis was performed to determine the association between inpatient MME consumption and extended LOS.

RESULTS

Of the 1042 study patients, 260 (24.9%) had Low-MME consumption, 523 (50.2%) had Medium-MME consumption, and 259 (24.9%) had High-MME consumption. A greater proportion of patients in the High cohort identified as non-Hispanic white (Low: 46.5% vs Medium: 61.4% vs High: 65.3%, p < 0.001), while the proportion of patients reporting any comorbidity did not vary across the cohorts (p = 0.940). The number of post-operative AEs experienced also did not vary across the cohorts (p = 0.629). A greater proportion of patients in the High cohort had an extended LOS (Low: 6.5% vs Medium: 8.6% vs High: 19.7%, p < 0.001), while a greater proportion of patients in the Low cohort had an increased cost of admission (Low: 33.1% vs Medium: 20.3% vs High: 26.6%, p < 0.001). The High cohort had increased 30-day readmission rates relative to the Low and Medium cohorts (Low: 0.8% vs Medium: 0.2% vs High: 1.5%, p = 0.049). Non-routine discharge rates did not vary among the cohorts (p = 0.441). On multivariate analysis, High-MME consumption was significantly associated with extended LOS, while Medium-MME consumption was not [Medium: aOR: 1.48, CI (0.83, 2.74), p = 0.193; High: aOR: 4.43, CI (2.47, 8.31), p < 0.001].

CONCLUSIONS

Our study showed that high post-operative-MME consumption was significantly associated with extended LOS in patients undergoing PSF for AIS. In light of these findings, changes to existing protocols that decrease the reliance on opioids for post-operative analgesia are merited to improve patient outcomes and reduce health-care expenditures.

Single-dose Intraoperative Methadone for Pain Management in Pediatric Tonsillectomy: A Randomized Double-blind Clinical Trial

BACKGROUND

More than 500,000 elective tonsillectomies are performed in U.S. children annually. Pain after pediatric tonsillectomy is common, often severe, and undertreated. There is no consensus on the optimal management of perioperative tonsillectomy pain. Methadone, with an elimination half-life of 1 to 2 days, has a longer duration of effect than short-duration opioids such as fentanyl. The primary objective of this study was to investigate the intraoperative use of methadone for pediatric tonsillectomy. It tested the hypothesis that methadone would result in less postoperative opioid use compared with short-duration opioids in children after tonsillectomy.

METHODS

This double-blind, randomized, parallel group trial in children (3 to 17 yr) undergoing tonsillectomy compared single-dose intravenous methadone (0.1 mg/kg then 0.15 mg/kg age-ideal body weight, in a dose escalation paradigm) versus as-needed short-duration opioid (fentanyl) controls. Opioid use, pain, and side effects were assessed in-hospital and 7 days postoperatively via electronic surveys. The primary outcome was total 7-day opioid use in oral morphine equivalents per kilogram (kg). Secondary outcomes were opioid use in the postanesthesia care unit, daily pain scores, and total number of 7-day opioid doses used.

RESULTS

Data analysis included 60 children (20/group), age 5.9 ± 3.7 yr (mean ± SD; median, 4; range, 3 to 17). Total 7-day opioid use (oral morphine equivalents per kg median [interquartile range]) was 1.5 [1.2, 2.1] in controls, 0.9 [0.1, 1.4] after methadone 0.1 mg/kg (P = 0.045), and 0.5 [0, 1.4] after methadone 0.15 mg/kg (P = 0.023). Postanesthesia care unit opioid use (oral morphine equivalents per kg) in controls was 0.15 [0.1, 0.3], 0.04 [0, 0.1] after methadone 0.1 mg/kg (P = 0.061). and 0.0 [0, 0.1] after methadone 0.15 mg/kg (P = 0.021). Postoperative pain scores were not different between groups. No serious opioid-related adverse events occurred.

CONCLUSIONS

This small initial study in children undergoing tonsillectomy found that single-dose intraoperative methadone at 0.15 mg/kg age ideal body weight was opioid-sparing compared with intermittent fentanyl.

EDITOR’S PERSPECTIVE

The Effects of Intraoperative Methadone on Postoperative Pain Control in Pediatric Patients: A Scoping Review

Inadequate perioperative pain control has deleterious effects on children's development and can lead to heightened pain experiences and the avoidance of future medical procedures. Reports of perioperative use of methadone in children are increasing, as it has a favorable pharmacodynamic profile; however, the effectiveness of methadone in reducing postoperative pain has not been established. We, therefore, aimed to provide a scoping review of the literature comparing the effect of intraoperative methadone versus other opioids on postoperative opioid consumption, pain scores, and adverse events in pediatric patients. We identified studies in PubMed, Scopus, Embase, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases from inception to January 2023. Postoperative opioid consumption, pain scores, and adverse events were extracted for analysis. We screened 1864 studies, of which 83 studies were selected for full-text review. Five studies were included in the final analysis. Postoperative opioid consumption was decreased overall in children who received methadone compared to those who did not. The majority of studies indicated that methadone was superior to other opioids in reported pain scores, while the frequency of adverse events was similar between the groups. Although the data reviewed highlight a potential benefit of intraoperative methadone in pediatric patients, 4 of the 5 studies had serious methodological concerns. Thus, we cannot make strong recommendations for the regular use of methadone in the perioperative setting at this time. Our results highlight the need for large, well-designed randomized trials to fully evaluate the safety and efficacy of intraoperative methadone in diverse pediatric surgical populations.

Chronic Postsurgical Pain in Children and Adolescents: A Call for Action

Chronic postsurgical pain (CPSP) affects a significant proportion of children and adolescents after major surgery and is a detriment to both short- and long-term recovery outcomes. While clinical characteristics and psychosocial risk factors for developing CPSP in children and adults are well established in the literature, there has been little progress on the prevention and management of CPSP after pediatric surgery. Limited evidence to support current pharmacologic approaches suggests a fundamentally new paradigm must be considered by clinicians to both conceptualize and address this adverse complication. This narrative review provides a comprehensive evaluation of both the known and emerging mechanisms that support our current understanding of CPSP. Additionally, we discuss the importance of optimizing perioperative analgesic strategies to mitigate CPSP based on individual patient risks. We highlight the importance of postoperative pain trajectories to identify those most at risk for developing CPSP, the early referral to multi-disciplinary pain clinics for comprehensive evaluation and treatment of CPSP, and additional work needed to differentiate CPSP characteristics from other chronic pain syndromes in children. Finally, we recognize ongoing challenges associated with the universal implementation of available knowledge about pediatric CPSP into practically useful care plans for clinicians.

Perioperative methadone for posterior spinal fusion in adolescents: Results from a double-blind randomized-controlled trial

BACKGROUND

Posterior spinal fusion is the most common surgical procedure performed for correction of adolescent idiopathic scoliosis in the United States. Intraoperative methadone has been shown to improve pain control in adult patients undergoing complex spine surgery, and current pediatric studies show encouraging results; however, prospective randomized-controlled trials are lacking in the pediatric literature.

AIMS

We conducted a single-center double-blind randomized-controlled trial to compare intraoperative use of methadone to morphine in pediatric patients undergoing posterior spinal fusion.

METHODS

A total of 47 adolescents undergoing posterior spinal fusion were randomized (stratified by sex) to either a methadone (n = 25) or morphine (n = 22) group. The primary outcome was postoperative opioid consumption. Secondary outcomes included postoperative pain severity, opioid-related side effects, and ratio of patient-controlled analgesia injections: attempts as a behavioral index of uncontrolled pain.

RESULTS

Patients in the methadone group consumed less total opioid postoperatively (median [interquartile range], 0.3 mg/kg [0.1, 0.5]) than patients in the morphine group (0.3 mg/kg [0.2, 0.6]), median difference [95% confidence interval] -0.07 [-0.2 to 0.02]; (p = .026). Despite the lower amount of opioid used postoperatively, pain scores for the methadone group (3.5 [3.0, 4.3]) were not significantly different from those in the morphine group (4.0 [3.2, 5.0]; p = .250). Groups did not differ on opioid-related side effects.

CONCLUSIONS

A two-dose intraoperative methadone regimen resulted in decreased opioid consumption compared to morphine. Although the clinical significance of these results may be limited, the analgesic equipoise without increased opioid-related side effects and potential for a lower incidence of chronic pain may tip the balance in favor of routine methadone use for adolescents undergoing posterior spinal fusion.

Opioid use disorder in pediatric populations: considerations for perioperative pain management and precision opioid analgesia

INTRODUCTION

Opioids are commonly used for perioperative analgesia, yet children still suffer high rates of severe post-surgical pain and opioid-related adverse effects. Persistent and severe acute surgical pain greatly increases the child's chances of chronic surgical pain, long-term opioid use, and opioid use disorder.

AREAS COVERED

Enhanced recovery after surgery (ERAS) protocols are often inadequate in treating a child's severe surgical pain. Research suggests that 'older' and longer-acting opioids such as methadone are providing better methods to treat acute post-surgical pain. Studies indicate that lower repetitive methadone doses can decrease the incidence of chronic persistent surgical pain (CPSP). Ongoing research explores genetic components influencing severe surgical pain, inadequate opioid analgesia, and opioid use disorder. This new genetic research coupled with better utilization of opioids in the perioperative setting provides hope in personalizing surgical pain management, reducing pain, opioid use, adverse effects, and helping the fight against the opioid pandemic.

EXPERT OPINION

The opioid and analgesic pharmacogenomics approach can proactively 'tailor' a perioperative analgesic plan to each patient based on underlying polygenic risks. This transition from population-based knowledge of pain medicine to individual patient knowledge can transform acute pain medicine and greatly reduce the opioid epidemic's socioeconomic, personal, and psychological strains globally.

The Pharmacological Treatment of Neuropathic Pain in Children

The International Association for the Study of Pain (IASP) defines neuropathic pain as pain caused by a lesion or disease of the somatosensory nervous system. It is characterized as a clinical condition in which diagnostic studies reveal an underlying cause of an abnormality in the peripheral or central nervous system. Many common causes of neuropathic pain in adults are rare in children. The purpose of this focused narrative review is, to 1) provide an overview of neuropathic pain in children, 2) highlight unique considerations related to the diagnosis and mechanisms of neuropathic pain in children, and 3) perform a comprehensive analysis of the pharmacological treatments available. We emphasize that data for routine use of pharmacological agents in children with neuropathic pain are largely inferred from adult literature with little research performed on pediatric populations, yet have clear evidence of harms to pediatric patients. Based on these findings, we propose risk mitigation strategies such as utilizing topical treatments whenever possible, assessing pain phenotyping to guide drug class choice, and considering pharmaceuticals in the broader context of the multidisciplinary treatment of pediatric pain. Furthermore, we highlight important directions for future research on pediatric neuropathic pain treatment.

Error traps and preventative strategies for adolescent idiopathic scoliosis spinal surgery

Anesthesia for posterior spinal fusion for adolescent idiopathic scoliosis remains one of the most common surgeries performed in adolescents. These procedures have the potential for significant intraprocedural and postoperative complications. The potential for pressure injuries related to prone positioning must be understood and addressed. Additionally, neuromonitoring remains a mainstay for patient care in order to adequately assess patient neurologic integrity and alert the providers to a reversible action. As such, causes of neuromonitoring signal loss must be well understood, and the provider should have a systematic approach to signal loss. Further, anesthetic design must facilitate intraoperative wake-up to allow for a definitive assessment of neurologic function. Perioperative bleeding risk is high in posterior spinal fusion due to the extensive surgical exposure and potentially lengthy operative time, so the provider should undertake strategies to reduce blood loss and avoid coagulopathy. Pain management for adolescents undergoing spinal fusion is also challenging, and inadequate analgesia can delay recovery, impede patient/family satisfaction, increase the risk of chronic postsurgical pain/disability, and lead to prolonged opioid use. Many of the significant complications associated with this procedure, however, can be avoided with intentional and evidence-based approaches covered in this review.

Pro-Con Debate: Role of Methadone in Enhanced Recovery After Surgery Protocols-Superior Analgesic or Harmful Drug?

Enhanced recovery after surgery (ERAS) protocols are standardized and designed to provide superior analgesia, reduce opioid consumption, improve patient recovery, and reduce hospital length of stay. Yet, moderate-to-severe postsurgical pain continues to afflict over 40% of patients and remains a major priority for anesthesia research. Methadone administration in the perioperative setting may reduce postoperative pain scores and have opioid-sparing effects, which may be beneficial for enhanced recovery. Methadone possesses a multimodal profile consisting of µ-opioid agonism, N-methyl-d-aspartate (NMDA) receptor antagonism, and reuptake inhibition of serotonin and norepinephrine. Furthermore, it may attenuate the development of chronic postsurgical pain. However, caution is advised with perioperative use of methadone in specific high-risk patient populations and surgical settings. Methadone's wide pharmacokinetic variability, opioid-related adverse effects, and potential negative impact on cost-effectiveness may also limit its use in the perioperative setting. In this PRO-CON commentary article, the authors debate whether methadone should be incorporated in ERAS protocols to provide superior analgesia with no increased risks.

Reducing Postoperative Length of Stay for Idiopathic Scoliosis Patients using Quality Improvement Methodology

Approximately 1%-3% of the US population is diagnosed with scoliosis. In addition, 80% of those diagnosed have idiopathic scoliosis, with about 10% requiring surgical intervention. This Quality Improvement initiative aimed to reduce the length of stay (LOS) after posterior spinal fusion for these patients. According to the Pediatric Health Information System, our institution had a poorer performance, with an actual LOS greater than or equal to the expected LOS compared with peer institutions.

METHODS

The aim was to increase the percentage of idiopathic scoliosis patients with a procedure to discharge LOS of less than or equal to 4 days after posterior spinal fusion from 39.13% to 90%. Interventions included implementing a new pain management protocol, a daily checklist, education on expectations of postoperative pain, and updated order sets.

RESULTS

Interventions improved patients discharged in less than 4 days from 39.13% to 93.48% (P ≤ 0.001), reducing the average postprocedure LOS from 4.93 to 2.59 (P ≤ 0.001) days. A key process measure tracked was the percentage of patients off the patient-control analgesia pump by postoperative day 2, which increased from 13% to 97.75% (P ≤ 0.001). These improvements did not affect the balancing measure of readmissions or Emergency Department visits for pain.

CONCLUSIONS

By implementing a more standardized pathway, including a patient-focused daily checklist for providers and families, we established expectations for LOS and pain. This checklist and updates to the pain management protocol successfully reduced the length of stay in idiopathic scoliosis patients after posterior spinal fusion.

Short-acting versus long-acting opioids for pediatric postoperative pain management

INTRODUCTION

Opioids are potent analgesics commonly used to manage children's moderate to severe perioperative pain in children. A wide range of short and long-acting opioids are used to treat surgical pain and will be reviewed in this article.

AREAS COVERED

Both short- and long-acting opioids contain unique therapeutic benefits and adverse effects; however, due to the side effect profile and safety concerns, lack of familiarity, and evidence with long-acting opioids to treat surgical pain, shorter-acting opioids have traditionally been used in children. Almost all opioids work by binding to the mu receptor. Methadone, a long-acting opioid, is an exception because it also has beneficial N-methyl-D-aspartate antagonist properties. Clinically methadone's properties could translate to improved analgesic outcomes, reduced risk of adverse events, less risk for acute hyperalgesia, tolerance and abuse potential, faster recovery, and reduced risk for chronic persistent surgical pain. This review article summarizes and compares the evidence of commonly used short and long-acting opioids for perioperative pain control in the pediatric population.

EXPERT OPINION

Individualized methadone therapy using pharmacogenomics has the potential to transform opioid use in pain management by improving patient safety and analgesic outcomes, thereby addressing the gaps in current standardized ERAS protocols.

What we know and what we don't know about the perioperative use of methadone in children and adolescents

Postoperative pain control is essential to optimizing patient outcomes, improving satisfaction, and allowing patients to resume their baseline functional activities. Methadone, a synthetic mu-opioid agonist, has multiple pharmacologic properties that may be optimal for perioperative use. Compared to other opioids, methadone has a longer duration of action, rapid onset, extended dosing intervals, high oral bioavailability, low cost, lack of active metabolites, and action on multiple receptors. The current literature examining the use of methadone in the perioperative care of children and adolescents is limited and most often reported within the context of spine or cardiothoracic surgery. Overall, these studies support the hypothesis that perioperative methadone in pediatric patients may decrease postoperative pain, opioid consumption, length-of-stay, and the incidence of some opioid-related side effects, like constipation and urinary retention. A variety of protocols for the perioperative use of methadone have been described, including a single intraoperative dose as well as multiple small doses within multimodal pain protocols. The superiority of these protocols has not been established. Like all opioids, methadone has a side effect profile which includes nausea, vomiting, reduced GI motility, sedation, and respiratory depression at high doses. There is also a concern that it can cause QTc prolongation in patients. The primary aim of this educational review is to examine the pharmacologic data, published perioperative protocols, dosing considerations, and risks and benefits associated with inclusion of methadone in analgesic regimens for surgical patients. A secondary aim is to introduce opportunities for research around the perioperative use of methadone in children and adolescents. Based on our review, we would prioritize establishing optimal procedure-specific methadone protocols, determining generalizability for use in routine pediatric surgeries, and investigating methadone safety and efficacy prospectively as the primary opioid for pain management in the postanesthesia care unit or postsurgical floors.

Postoperative analgesia for complex spinal surgery

PURPOSE OF REVIEW

Complex spinal surgery is associated with significant postoperative pain. The purpose of this paper is to review recent literature on postoperative pain management in adult and adolescent patients having complex spinal surgery.

RECENT FINDINGS

We conducted a literature search using the Medline database for relevant publications from 2020 to 2022 on postoperative pain after complex spinal surgery. Although opioids remain the mainstay to manage pain after complex spinal surgery, they are associated with adverse effects. Multimodal analgesia may be used to reduce these adverse effects by combining different drugs targeting different parts of the pain pathway. Recent publications suggest continuous low dose fentanyl or morphine infusion, methadone, intravenous paracetamol and ibuprofen, ketorolac, ketamine, magnesium infusion, lidocaine infusion and dexmedetomidine appear to be effective and safe to manage pain after complex spinal surgery. Regional techniques including bilateral erector spinae block, interfascial plane block and intrathecal morphine also appear to be effective and safe.

SUMMARY

Pain management after complex spinal surgery remains challenging. Therefore, further studies are still required to determine the optimal multimodal analgesic regimen for these patients.

Scheduled methadone reduces overall opioid requirements after pediatric posterior spinal fusion: A single center retrospective case series

BACKGROUND

Posterior spinal fusion to correct adolescent idiopathic scoliosis is associated with significant postoperative pain. Different modalities have been reported as part of a multimodal analgesic plan. Intravenous methadone acts as a mu-opioid agonist and N-Methyl-D-aspartate (NMDA) antagonist and has been shown to have opioid-sparing effects. Our multimodal approach has included hydromorphone patient-controlled analgesia (PCA) with and without preincisional methadone, and recently postoperative methadone without a PCA.

AIMS

We hypothesized that a protocol including scheduled postoperative methadone doses would reduce opioid usage compared to PCA-based strategy.

METHODS

A retrospective chart review of patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis between 2015 and 2020 was performed. There were three patient groups: Group PCA received a hydromorphone PCA without methadone; Group PCA + Methadone received preincisional methadone and a hydromorphone PCA; Group Methadone received preincisional methadone, scheduled postoperative methadone, and no PCA. The primary outcome was postoperative opioid use over 72 h. Secondary outcomes included pain scores, sedation scores, and length of stay.

RESULTS

Group PCA (n = 26) consumed 0.33 mg/kg (95% CI [0.28, 0.38]) total hydromorphone equivalents, Group PCA + methadone (n = 39) 0.30 mg/kg (95% CI [0.25, 0.36]) total hydromorphone equivalents, and Group methadone (n = 22) 0.18 mg/kg (95% CI [0.15, 0.21]) total hydromorphone equivalents (p = .00096). There were no statistically significant differences between the groups for secondary outcomes.

CONCLUSION

A protocol with intraoperative and scheduled postoperative methadone doses resulted in a 45% reduction in opioid usage compared to a PCA-based protocol with similar analgesia after pediatric posterior spinal fusion.

Intraoperative Methadone and Short Stay Spine Surgery: Possible Barriers to Implementation and Future Opportunities

The frequency of shorter stay spine surgery is increasing. Acute pain is a common barrier to discharge following spine surgery. Long-acting opioid medications like methadone have the potential to provide sustained analgesia when given intraoperatively. Methadone has been effectively used in complex spine surgery, cardiac surgery, and more recently applied to ambulatory procedures. In this article, we summarize the pertinent available literature on the use of intraoperative methadone for spine surgery as well as the recent data on intraoperative methadone for ambulatory surgery. The aim of this perspectives article is to describe the potential opportunities for applying intraoperative methadone to shorter stay spine surgery as well as barriers to more widespread use. While there are currently no trials that have specifically studied methadone for shorter stay spine surgery specifically to date, it is a promising area for future research.

Error traps in acute pain management in children

Providing effective acute pain management to hospitalized children can help improve outcomes, decrease length of stay, and increase patient and parental satisfaction. Error traps (circumstances that lead to erroneous actions or undesirable consequences) can result in inadequately controlled pain, unnecessary side effects, and adverse events. This article highlights five error traps encountered when managing acute pain in children. They include failure to appropriately assess pain, optimally utilize regional anesthesia, select suitable systemic analgesics, identify and treat medication-related side effects, and consider patient characteristics when choosing medication or dosing route. These issues are easily addressed when the clinician is cognizant of ways to anticipate, identify, and mitigate or avoid these errors.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Rediscovery of Methadone to Improve Outcomes in Pain Management

Clinically, methadone is most known for its use in the treatment of opioid maintenance therapy. However, methadone's pharmacological profile makes it an excellent analgesic that can enhance acute and chronic pain management. It is a potent μ-receptor agonist with a longer elimination half-life than most clinically used opioids. In addition, methadone inhibits serotonin and norepinephrine uptake, and it is an N-methyl-D-aspartate antagonist. These distinct analgesic pathways mediate hyperalgesic, allodynic, and neuropathic pain. Its unique analgesic properties provide several essential benefits in perioperative use, neuropathic pain, cancer, and noncancer pain. Despite these proven clinical utilities, methadone has not been used widely to treat acute and chronic pain in opioid naïve patients. This article describes the unique pharmacology of methadone and provides emerging evidence to support its application in acute and chronic pain management. Pain management options and guidelines for surgical patients on methadone are discussed as well.

Pharmacokinetic modeling of R and S-Methadone and their metabolites to study the effects of various covariates in post-operative children

Methadone is a synthetic opioid used as an analgesic and for the treatment of opioid abuse disorder. The analgesic dose in the pediatric population is not well-defined. The pharmacokinetics (PKs) of methadone is highly variable due to the variability in alpha-1 acid glycoprotein (AAG) and genotypic differences in drug-metabolizing enzymes. Additionally, the R and S enantiomers of methadone have unique PK and pharmacodynamic properties. This study aims to describe the PKs of R and S methadone and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in pediatric surgical patients and to identify sources of inter- and intra-individual variability. Children aged 8-17.9 years undergoing orthopedic surgeries received intravenous methadone 0.1 mg/kg intra-operatively followed by oral methadone 0.1 mg/kg postoperatively every 12 h. Pharmacokinetics of R and S methadone and EDDP were determined using liquid chromatography tandem mass spectrometry assays and the data were modeled using nonlinear mixed-effects modeling in NONMEM. R and S methadone PKs were well-described by two-compartment disposition models with first-order absorption and elimination. EDDP metabolites were described by one compartment disposition models with first order elimination. Clearance of both R and S methadone were allometrically scaled by bodyweight. CYP2B6 phenotype was a determinant of the clearance of both the enantiomers in an additive gene model. The intronic CYP3A4 single-nucleotide polymorphism (SNP) rs2246709 was associated with decreased clearance of R and S methadone. Concentrations of AAG and the SNP of AAG rs17650 independently increased the volume of distribution of both the enantiomers. The knowledge of these important covariates will aid in the optimal dosing of methadone in children.

Novel associations between CYP2B6 polymorphisms, perioperative methadone metabolism and clinical outcomes in children

Aim: Methadone exhibits significant variability in clinical response. This study explores the genetic influence of variable methadone pharmacokinetics. Methods: This is a prospective study of methadone in children undergoing major surgery. CYP2B6 genotyping, plasma methadone and metabolite levels were obtained. Clinical outcomes include pain scores and postoperative nausea and vomiting (PONV). Results: CYP2B6 poor metabolizers (*6/*6) had >twofold lower methadone metabolism compared with normal/rapid metabolizers. The incidence of PONV was 4.7× greater with CYP2B6 rs1038376 variant. AG/GG variants of rs2279343 SNP had 2.86-fold higher incidence of PONV compared with the wild variant (AA). Nominal associations between rs10500282, rs11882424, rs4803419 and pain scores were observed. Conclusion: We have described novel associations between CYP2B6 genetic variants and perioperative methadone metabolism, and associations with pain scores and PONV.

A Novel Perioperative Multidose Methadone-Based Multimodal Analgesic Strategy in Children Achieved Safe and Low Analgesic Blood Methadone Levels Enabling Opioid-Sparing Sustained Analgesia With Minimal Adverse Effects

BACKGROUND

Intraoperative methadone, a long-acting opioid, is increasingly used for postoperative analgesia, although the optimal methadone dosing strategy in children is still unknown. The use of a single large dose of intraoperative methadone is controversial due to inconsistent reductions in total opioid use in children and adverse effects. We recently demonstrated that small, repeated doses of methadone intraoperatively and postoperatively provided sustained analgesia and reduced opioid use without respiratory depression. The aim of this study was to characterize pharmacokinetics, efficacy, and safety of a multiple small-dose methadone strategy.

METHODS

Adolescents undergoing posterior spinal fusion (PSF) for idiopathic scoliosis or pectus excavatum (PE) repair received methadone intraoperatively (0.1 mg/kg, maximum 5 mg) and postoperatively every 12 hours for 3-5 doses in a multimodal analgesic protocol. Blood samples were collected up to 72 hours postoperatively and analyzed for R-methadone and S-methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidene (EDDP) metabolites, and alpha-1 acid glycoprotein (AAG), the primary methadone-binding protein. Peak and trough concentrations of enantiomers, total methadone, and AAG levels were correlated with clinical outcomes including pain scores, postoperative nausea and vomiting (PONV), respiratory depression, and QT interval prolongation.

RESULTS

The study population included 38 children (10.8-17.9 years): 25 PSF and 13 PE patients. Median total methadone peak plasma concentration was 24.7 (interquartile range [IQR], 19.2-40.8) ng/mL and the median trough was 4.09 (IQR, 2.74-6.4) ng/mL. AAG concentration almost doubled at 48 hours after surgery (median = 193.9, IQR = 86.3-279.5 µg/mL) from intraoperative levels (median = 87.4, IQR = 70.6-115.8 µg/mL; P < .001), and change of AAG from intraoperative period to 48 hours postoperatively correlated with R-EDDP (P < .001) levels, S-EDDP (P < .001) levels, and pain scores (P = .008). Median opioid usage was minimal, 0.66 (IQR, 0.59-0.75) mg/kg morphine equivalents/d. No respiratory depression (95% Wilson binomial confidence, 0-0.09) or clinically significant QT prolongation (median = 9, IQR = -10 to 28 milliseconds) occurred. PONV occurred in 12 patients and was correlated with morphine equivalent dose (P = .005).

CONCLUSIONS

Novel multiple small perioperative methadone doses resulted in safe and lower blood methadone levels, <100 ng/mL, a threshold previously associated with respiratory depression. This methadone dosing in a multimodal regimen resulted in lower blood methadone analgesia concentrations than the historically described minimum analgesic concentrations of methadone from an era before multimodal postoperative analgesia without postoperative respiratory depression and prolonged corrected QT (QTc). Larger studies are needed to further study the safety and efficacy of this methadone dosing strategy.