Pain

Perioperative Methadone for Analgesia

While Methadone is well known for its role in medication assisted treatment for substance use disorders, its long duration of analgesia has perhaps been under-appreciated for surgical analgesia. In addition to its opioid action it has anti-hyperalgesic and anti-allodynic properties through NMDA antagonism, and Serotonin-Norepinephrine re-uptake inhibition. Doses generally given are 20mg or 0.2mg/kg. Studies indicate 24 hours or more analgesia with reduced need for supplemental analgesia.

Studies are ongoing as to its safety in different at-risk populations, e.g. coexisting medications, older, frail, cardiorespiratory disease, OSA, but this APSF article provides a great primer on Methadone in the perioperative period.

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Intranasal Ketamine for Extremity Injuries in Children

A small non-inferiority study on children aged 8- 17 with extremity injuries (mostly fractures) compared intranasal Ketamine 1.5 mg/kg with Fentanyl 2 mcg/kg.

Ketamine produced effective analgesia that was non-inferior to Fentanyl, but did have more what are characterized as minor side effects, eg. dizziness or somnolence; these were short-lived. No serious adverse events, such as respiratory or hemodynamic, occurred.

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EMLA and Infants

While we strive to safely minimize pediatric pain, this meta-analysis found that the use of EMLA cream on the skin for venipuncture in infants less than 3 months did not seem to provide much benefit. EMLA had minimal benefits compared to placebo and no benefit compared to sucrose and/or breastfeeding. Rather it only increased methemoglobin levels and skin blanching. The authors caution it may not be applicable to older infants.

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Labor Neuraxial Analgesia Variation

Labor epidurals should be available for all births on maternal request unless contraindicated. This US study found quite a variation between states in neuraxial labor analgesia – from 37 – 80%.

Higher rates were associated with no prior birth, previous Cesarean, labor augmentation or induction. Factors inversely associated with neuraxial analgesia were older maternal age, nonwhite race and Hispanic ethnicity, no private insurance or no insurance, twelfth grade or less as the highest level of education, and late or no prenatal care, and the odds reduced with non-physician birth attendants and midwives.

Efforts should be made to decipher the meaning of these variations in terms of sociodemographic and economic influences, disparity, vulnerable groups and access to quality obstetric anesthesia care.

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Cognitive Effects of Perioperative Pregabalin

Gabapentinoids have been shown in many studies to reduce postoperative pain but side effects such as somnolence, dizziness and even respiratory depression have been also reported (not to mention Gabapentinoid misuse and dependence in longer term use). This secondary analysis adds a further caveat in that Pregabalin may increase the risk of developing impaired postoperative cognitive performance, and this may be more important in older or frail patients.

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Ultrarestrictive Opioid Policy

This study in gynecologic oncology surgery implemented a policy whereby patients undergoing ambulatory or minimally invasive surgery (laparoscopic or robotic approach) were not prescribed opioids at discharge unless they required more than 5 doses of oral or intravenous opioids while in the hospital, and patients who underwent a laparotomy were provided a 3-day opioid pain medication supply at discharge.

Importantly the reduction in opioid use was not accompanied by an increase in pain scores. Such policies mirror the use of opioid free (or sparing) anesthetic techniques which are increasingly employed. 

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Chronic Pain

A comprehensive review of how acute pain may become chronic, and a detailed analysis of the complex mechanisms, – genetic, environmental, socioeconomic, cognitive-affective etc. The authors provide a roadmap for future therapies that should go beyond a cognitive behavioural acceptance of pain in favour of new treatment approaches.

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Buprenorphine Peri-Operatively

A review on managing Buprenorphine in the perioperative period notes the disparate views and protocols in use ranging from continuing it to weaning off and replacing with full agonists. The overall conclusion is that the ‘main impetus for discontinuation, i.e., inadequate pain management, may be based on expert opinion and not on the existing evidence’…”no evidence against continuing buprenorphine perioperatively, especially when the dose is < 16 mg SL daily.

The authors recommend that future studies require standardized reporting of median doses, details on the route of delivery, dosing schedules and any dosing changes, and rates of addiction relapse, including long-term morbidity and mortality where possible”.

Consultation with the prescribing expert in substance use would seem highly advisable when such patients present to us to balance the probable greater need for analgesics with safety and relapse potential.

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