Methadone analgesia in the critically ill

Substance Use Disorder in Critical Care

Substance use disorders are increasing in the growing older adult population in the U.S. and abroad. Most interventions fail to account for the unique physical and psychosocial risk factors associated with substance use disorder. The older adult makes up a large portion of ICU admits and it is imperative to identify appropriate methods of prevention and treatment in this patient population. Important components of substance use disorder assessment and treatment in the older ICU patient were identified from the literature. Increased morbidity related to age-related conditions, pharmacologic concerns, withdrawals, and stigma were identified as essential items to consider when caring for the older ICU patient with substance use disorder.

Use of Methadone Versus Oxycodone to Facilitate Weaning of Parenteral Opioids in Critically Ill Adult Patients

BACKGROUND

No previous literature has compared methadone with oxycodone for intravenous (IV) opioid weaning.

OBJECTIVE

To determine if a weaning strategy using enteral methadone or oxycodone results in faster time to IV opioid discontinuation.

METHODS

This was a single-center, retrospective, cohort medical record review of mechanically ventilated adults in an intensive care unit (ICU) who received a continuous IV infusion of fentanyl or hydromorphone for ≥72 hours and an enteral weaning strategy using either methadone or oxycodone from January 1, 2020, through December 31, 2021. Differences between groups were controlled for using Cox proportional hazards models. The primary outcome was time to continuous IV opioid discontinuation from the initiation of enteral opioids. Secondary outcomes included the primary endpoint stratified for COVID-19, duration of mechanical ventilation, ICU and hospital length of stay, and safety measures.

RESULTS

Ninety-three patients were included, with 36 (38.7%) patients receiving methadone and 57 (61.3%) receiving oxycodone. Patients weaned using methadone received IV opioids significantly longer before the start of weaning (P = 0.04). However, those on methadone had a significantly faster time to discontinuation of IV opioids than those on oxycodone, mean (standard deviation) 104.7 (79.4) versus 158.3 hours (171.2), P = 0.04, and, at any time, were 1.89 times as likely to be weaned from IV opioids (hazard ratio, HR 1.89, 95% confidence interval, CI 1.16-3.07, P = 0.01).

CONCLUSION AND RELEVANCE

This was the first study showing enteral methadone was associated with a shorter duration of IV opioids without differences in secondary outcomes compared with oxycodone. Prospective research is necessary to confirm this finding.

ERAS Protocol Options for Perioperative Pain Management of Substance Use Disorder in the Ambulatory Surgical Setting

Even prior to the COVID-19 pandemic, rates of ambulatory surgeries and ambulatory patients presenting with substance use disorder were increasing, and the end of lockdown has further catalyzed the increasing rates of ambulatory patients presenting for surgery with substance use disorder (SUD). Certain subspecialty groups of ambulatory procedures have already established protocols to optimize early recovery after surgery (ERAS), and these groups have subsequently enjoyed improved efficiency and reduced adverse outcomes as a result. In this present investigation, we review the literature as it relates to substance use disorder patients, with a particular focus on pharmacokinetic and pharmacodynamic profiles, and their resulting impact on the acute- or chronic user ambulatory patient. The systematic literature review findings are organized and summarized. We conclude by identifying areas of opportunity for further study, specifically with the aim of developing a dedicated ERAS protocol for substance use disorder patients in the ambulatory surgery setting. - Healthcare in the USA has seen an increase in rates of both substance use disorder patients and separately in ambulatory surgery cases. - Specific perioperative protocols to optimize outcomes for patients who suffer from substance use disorder have been described in recent years. - Agents of interest like opioids, cannabis, and amphetamines are the top three most abused substances in North America. - A protocol and recommend further work should be done to integrate with concrete clinical data, in which strategies should be employed to confer benefits to patient outcomes and hospital quality metrics like those enjoyed by ERAS protocol in other settings.

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.

Novel use of methadone intraoperatively in pediatric burn patients

Burn injury in children can cause severe and chronic physical and mental sequelae. Opioids are a mainstay in burn pain management but increasing utilization in this country has led to concern for their continued use and potential for dependence. Methadone is a long-acting analgesic that targets the N-methyl-D-aspartate (NMDA) receptor in addition to the mu opioid receptor and has benefit in adult burn patients. However, its use in the pediatric burn population has been less robustly studied. This is a retrospective cohort study at a single Level 1 Burn Center whose primary aim is to compare opioid utilization 36 hours postoperatively between pediatric burn patients who received intraoperative, intravenous methadone and those who did not. Secondary aim was to describe differences in methadone-related complications between the cohorts. There was decreased opioid utilization measured by median morphine equivalents per kilogram (ME/kg) postoperatively in the methadone cohort compared to the control cohort (0.54mg/kg v. 0.77mg/kg, p = 0.18). No adverse events were noted upon chart review. The data suggests methadone use is beneficial in pediatric burn patients, but further prospective studies are warranted on a larger population.

Pain Management Considerations in Patients with Opioid Use Disorder Requiring Critical Care

The opioid epidemic has resulted in increased opioid-related critical care admissions, presenting challenges in acute pain management. Limited guidance exists in the management of critically ill patients with opioid use disorder (OUD). This narrative review provides the intensive care unit (ICU) clinician with guidance and treatment options, including non-opioid analgesia, for patients receiving medications for opioid use disorder (MOUD) and for patients actively misusing opioids. Verification and continuation of the patient's outpatient MOUD regimen, specifically buprenorphine and methadone formulations, assessment of pain and opioid withdrawal, and treatment of acute pain with non-opioid analgesia, nonpharmacologic strategies, and short-acting opioids as needed, are all essential to adequate management of acute pain in patients with OUD. A multidisciplinary approach to treatment and discharge planning in patients with OUD may be beneficial to engage patients with OUD early in their hospital stay to prevent withdrawal, stabilize their OUD, and to reduce the risk of unplanned discharge and other associated morbidity. This article is protected by copyright. All rights reserved.

Weaning Analgosedation in Patients Requiring Prolonged Mechanical Ventilation

Although research supports the minimization of sedation in mechanically ventilated patients, many patients with severe acute respiratory distress syndrome (ARDS) receive prolonged opioid and sedative infusions. ICU teams face the challenge of weaning these medications, balancing the risks of sedation with the potential to precipitate withdrawal symptoms. In this article, we use a clinical case to discuss our approach to weaning analgosedation in patients recovering from long-term mechanical ventilation. We believe that a protocolized, multimodal weaning strategy implemented by a multidisciplinary care team is required to reduce potential harm from both under- and over-sedation. At present, there is no strong randomized clinical trial evidence to support a particular weaning strategy in adult ICU patients, but appraisal of the existing literature in adults and children can guide decision-making to enhance the recovery of these patients.

Methadone bioavailability and dose conversion implications with intravenous and enteral administration: A scoping review

PURPOSE

Despite its availability for more than 70 years, many details concerning methadone remain contentious, such as the dosing equivalents for intravenous and enteral administration. A scoping review was performed to evaluate whether existing literature on methadone bioavailability in human subjects support the current recommendation that an equivalent enteral dose is twice the intravenous dose.

METHODS

A librarian-assisted search of the PubMed and EMBASE databases identified all English-language articles with the terms methadone and bioavailability and/or conversion in the title or abstract published from inception though December 2019. A manual search of references was also performed to identify any additional articles. Studies were included in a scoping review if they were published in English and evaluated methadone bioavailability in human subjects.

RESULTS

Among 65 publications initially identified, 6 studies involving a total of 50 patients were included in the review. Bioavailability data for healthy volunteers and patients with opioid use disorder, metastatic cancer, chronic pain from malignant or nonmalignant disease were available for analysis. The pooled mean (95% confidence interval) bioavailability (F) was 85.4% (75.2%-95.6%), with heterogeneity (I2) of 0. In the 4 studies that provided individual patient-level data, F was >50% in 40 of 42 patient measurements (95.2%) and ≥75% in 33 of 42 patient measurements (78.6%).

CONCLUSION

Available evidence suggests the bioavailability of methadone is generally more than 75%, there is limited evidence for the currently recommended 1:2 ratio (intravenous:enteral), and a more appropriate dosing ratio may be 1:1.3. This scoping review underscores the need for further research to establish an effective and safe ratio when converting between intravenous and enteral dosing formulations of methadone.

Methadone's Effect on Cardiac Repolarization: Safety in the PICU

OBJECTIVES

Opioids are routinely used in the PICU. Methadone is an effective method of preventing and treating iatrogenic opioid withdrawal; however, it carries an Food and Drug Administration Boxed Warning due to the potential to prolong the corrected QT interval and potentially lead to life-threatening arrhythmias. Guidelines on the safe use of methadone have limited applicability to children since their cardiac intervals differ from those of adults. There is little data on the electrophysiologic effects in the pediatric population. We set out to describe the safety of methadone use in the PICU, hypothesizing that methadone does not cause a significant change in corrected QT interval from baseline.

DESIGN

Retrospective cohort study.

SETTING

Children's Hospital of Wisconsin, Milwaukee, WI.

PATIENTS

Fifty-one patients, age less than or equal to 18 years old, initiated on methadone during PICU admission, over an 11-month period, for the prevention or treatment of opioid withdrawal.

INTERVENTIONS

Retrospective data queried from the electronic health record and stored telemetry waveforms obtained from an automated real-time patient data acquisition software system (BedMasterEx; Anandic Medical Systems AG, Feuerthalen, Switzerland).

MEASUREMENTS AND MAIN RESULTS

Corrected QT intervals were not significantly different at 12 hours, 96 hours, or PICU discharge (p values: 0.57, 0.54, and 0.34) when compared to baseline. The median change in corrected QT from baseline to 12 hours after the first dose of methadone was 5 ms (interquartile range, -12 to 11 ms), 0 ms to steady state (interquartile range, -18 to 18 ms), and 5 ms from baseline to 12 hours after the highest dose of methadone (interquartile range, -14 to 16 ms). The most common primary diagnosis was structural heart disease (29% of subjects) in our cohort and every subject that experienced an increase in corrected QT interval greater than or equal to 40 ms had some form of structural heart disease.

CONCLUSIONS

Methadone did not significantly prolong the corrected QT interval in a population of critically ill children, suggesting that it can be safely used in this population, although patients with structural heart disease may warrant closer monitoring.

The effect of intraoperative methadone during pediatric cardiac surgery on postoperative opioid requirements

BACKGROUND

Pain control in pediatric patients undergoing cardiac surgery presents a unique challenge. Postoperatively, many of these patients require long-term opioid infusions and sedation leading to need for prolonged weaning from opioids and longer hospital stays. We hypothesized that intravenous methadone as the sole opioid in children having cardiac surgery with cardiopulmonary bypass would improve perioperative pain control and decrease overall perioperative use of opioid analgesics and sedatives.

METHODS

We instituted a practice change involving pediatric patients aged <18 years who underwent cardiac surgery with cardiopulmonary bypass over a 14-month period, comparing the patient population who had surgery prior to the institution of intraoperative methadone usage to patients who had surgery in the months following. We then separated patients into two groups: neonatal (aged < 30 days) and non-neonatal (aged > 30 days to 18 years). Our primary outcome was intraoperative and postoperative opioid requirements measured in morphine equivalents intraoperatively, during the first 24 hours postoperatively, and up to postoperative day 7. Secondary outcomes included extubation rates in the OR, pain and sedation scores, sedation requirements, and time to start of oxycodone.

RESULTS

Patients in both groups had similar demographics. In neonatal patients, the postintervention group required significantly lower doses of intraoperative opioids. There was no statistically significant difference in postoperative opioid use. In non-neonatal patients, the postintervention group required significantly less intraoperative opioids. Postoperatively, those in the postintervention group required significantly less opioids in the first 24 hours.

CONCLUSION

The use of intraoperative methadone appears to be a reasonable alternative to the use of fentanyl with potential other benefits both intra- and postoperatively of decreased total dose of opioids and other sedatives. Future studies will assess for any improvement in total postoperative opioid requirements during the total hospital stay, and potential use of methadone by the ICU team.

Challenges in anaesthesia and pain management for burn injuries

Burn-injured patients provide unique challenges to those providing anaesthesia and pain management. This review aims to update both the regular burn anaesthetist and the anaesthetist only occasionally involved with burn patients in emergency settings. It addresses some aspects of care that are perhaps contentious in terms of airway management, fluid resuscitation, transfusion practices and pharmacology. Recognition of pain management failures and the lack of mechanism-specific analgesics are discussed along with the opioid crisis as it relates to burns and nonpharmacological methods in the management of distressed patients.

Risk Factors and Prevalence of QTc Prolongation in Adult Burn Patients Receiving Methadone

Methadone is an opioid commonly used for acute pain management in burn patients. One adverse effect of methadone is QTc interval prolongation, which may be associated with adverse cardiac outcomes. There is currently a paucity of data regarding risk of QTc prolongation in burn patients taking methadone and a lack of evidence-based recommendations for monitoring strategies in this population. The study objective was to determine the prevalence, risk factors, and cardiac outcomes related to methadone-associated QTc prolongation in adult burn patients. A total of 91 patients were included and were divided into groups according to maximum QTc. QTc prolongation was defined as greater than or equal to 470 ms (males) or 480 ms (females). There were no differences between groups regarding patient-specific risk factors, baseline QTc, or time to longest QTc. Patients in the prolonged QTc group had a higher rate of cardiac events (44% vs 9%; P < .001), higher median (IQR) change from baseline to longest QTc (61 ms [18,88] vs 23 ms [13,38]; P < .001), higher median (IQR) total daily dose of methadone (90 mg [53,98] vs 53 mg [30,75]; P = .004), and longer median (IQR) length of stay (53 [33,82] vs 35 [26,52] days; P = .008). QTc prolongation in burn patients was associated with increased methadone dose and resulted in a higher rate of cardiac events. This study was the first of its kind to look at risk factors and cardiac outcomes associated with methadone use in burn patients.

Opioid and Benzodiazepine Iatrogenic Withdrawal Syndrome in Patients in the Intensive Care Unit

Iatrogenic withdrawal syndrome is an increasingly recognized issue among adult patients in the intensive care unit. The prolonged use of opioids and benzodiazepines during the intensive care unit stay and preexisting disorders associated with their use put patients at risk of developing iatrogenic withdrawal syndrome. Although research to date is scant regarding iatrogenic withdrawal syndrome in adult patients in the intensive care unit, it is important to recognize and adequately manage iatrogenic withdrawal syndrome in order to prevent possible negative outcomes during and after a patient's intensive care unit stay. This article discusses in depth 8 studies of iatrogenic withdrawal syndrome among adult patients in the intensive care unit. It also addresses important aspects of opioid and benzodiazepine iatrogenic withdrawal syndrome, including prevalence, risk factors, and assessment and considers its prevention and management.

[Pain therapy in intensive care patients]

After intensive care unit (ICU) treatment, the recollection of experienced pain is one of the most burdensome aftermaths. In addition, pain has several negative physiological consequences. The majority of patients report moderate to severe pain while being treated on an ICU, often caused by diagnostic or therapeutic procedures. Pain and its functional consequences during ICU treatment should therefore be systematically recorded and treated. Due to their high analgesic potency, pharmacological pain therapy focuses on opioids; however, gastrointestinal motility disturbance and development of tolerance are disadvantages. When applying non-opioids, such as non-steroidal anti-inflammatory drugs (NSAID) and paracetamol, attention should be paid to their possible organ toxicity. Ketamine and α₂-antagonists can complement the analgesic concept. Analogous to its perioperative administration, intravenous lidocaine in intensive care seems acceptable because of a favorable impact on opioid requirements and gastrointestinal motility. When using regional anesthesia the positive therapeutic effect and the possible complications need to be carefully weighed. Non-pharmaceutical procedures, especially transcutaneous electrical nerve stimulation (TENS), have proven successful in postoperative pain management. Even if only limited data from intensive care are available, a therapeutic attempt seems justifiable because of the low risk of complications.

Use of Methadone to Reverse Opioid Escalation in a Patient With Surgical Pain

Acute pain is a prevalent issue for patients recovering from surgical procedures. Methadone has been recognized as a unique option for treatment of surgical pain due to its multiple mechanisms of analgesia and its potential to decrease tolerance to other opioids. Studies of methadone use in postoperative settings are sparse in part due to safety concerns, such as complex pharmacokinetics, risk of respiratory depression, and association with arrhythmias. In this case study of a 70-year-old male with postsurgical abdominal pain, methadone utilization over a period of 9 days resulted in patient-reported analgesia and aided in de-escalating overall opioid use. More studies are needed to develop guidance on how methadone can be used to relieve pain following surgical procedures.

Iatrogenic Opioid Withdrawal in Critically Ill Patients: A Review of Assessment Tools and Management

OBJECTIVE

To (1) provide an overview of the epidemiology, clinical presentation, and risk factors of iatrogenic opioid withdrawal in critically ill patients and (2) conduct a literature review of assessment and management of iatrogenic opioid withdrawal in critically ill patients.

DATA SOURCES

We searched MEDLINE (1946-June 2017), EMBASE (1974-June 2017), and CINAHL (1982-June 2017) with the terms opioid withdrawal, opioid, opiate, critical care, critically ill, assessment tool, scale, taper, weaning, and management. Reference list of identified literature was searched for additional references as well as www.clinicaltrials.gov .

STUDY SELECTION AND DATA EXTRACTION

We restricted articles to those in English and dealing with humans.

DATA SYNTHESIS

We identified 2 validated pediatric critically ill opioid withdrawal assessment tools: (1) Withdrawal Assessment Tool-Version 1 (WAT-1) and (2) Sophia Observation Withdrawal Symptoms Scale (SOS). Neither tool differentiated between opioid and benzodiazepine withdrawal. WAT-1 was evaluated in critically ill adults but not found to be valid. No other adult tool was identified. For management, we identified 5 randomized controlled trials, 2 prospective studies, and 2 systematic reviews. Most studies were small and only 2 studies utilized a validated assessment tool. Enteral methadone, α-2 agonists, and protocolized weaning were studied.

CONCLUSION

We identified 2 validated assessment tools for pediatric intensive care unit patients; no valid tool for adults. Management strategies tested in small trials included methadone, α-2 agonists, and protocolized sedation/weaning. We challenge researchers to create validated tools assessing specifically for opioid withdrawal in critically ill children and adults to direct management.

The use of methadone to facilitate opioid weaning in pediatric critical care patients: a systematic review of the literature and meta-analysis

BACKGROUND

Continuous opioid infusion therapy is commonly utilized in the pediatric intensive care setting to treat pain and facilitate tolerance of invasive therapies. Transitioning to methadone is one common strategy for weaning from continuous opioid infusions, but in practice this transition can be challenging, and many children still experience iatrogenic withdrawal.

AIM

We reviewed the literature to evaluate the best available evidence to guide methadone therapy in this setting, and to summarize associated adverse events.

METHODS

We included all studies of methadone used to facilitate weaning from continuous opioid infusions in pediatric critical care patients, including medical, cardiac, and surgical patients, excluding case reports and studies treating neonatal abstinence syndrome, or acute or chronic pain. Medline, Embase, and CINAHL databases from inception to May 2015 were queried; references of included works and conference proceedings were also reviewed. Two authors independently extracted data from each study. Meta-analysis with fixed- and random-effects models was used to pool results of studies when applicable.

RESULTS

Twelve studies involving 459 patients met criteria for inclusion. A wide variety of methadone dosing and taper strategies were reported. Mean inpatient methadone taper times varied widely, from 4.3 to 26.2 days. Excessive sedation was the most frequently reported adverse event, occurring in up to 16% of patients. Withdrawal occurred in 27% of patients among studies reporting this outcome. In three of three studies in which a new methadone protocol was introduced, a decreased proportion of patients experienced withdrawal (standardized mean difference, SMD = -0.60, 95% CI = -0.998 to -0.195, P = 0.004).

CONCLUSION

We did not identify sufficient evidence to recommend any particular methadone weaning strategy, or to recommend methadone over other medications or prescribed infusion weaning, for successful weaning of continuous opioid infusions in the pediatric intensive care setting.