Pharmacology

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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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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IV Iron and Postpartum Anemia

Intravenous iron has become more popular for both preoperative and postoperative anemia as a faster and more efficient alternative to oral iron, with less reactions with modern formulations.

This review and meta-analysis found that hemoglobin concentrations at 6 weeks postpartum were almost 1 g/dL higher in women who received intravenous iron compared to oral iron, with no serious side effects. It lends support to the increasing use of intravenous iron in the obstetric as well as other surgical populations.

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Dexmedetomidine vs. Remifentanil Sedation

This study specifically in endobronchial ultrasound-guided transbronchial needle aspiration sedation compared these two agents. Remifentanil not unexpectedly, as an opioid, caused more desaturations, apnea and bradypnea. There were no differences in operating conditions, sedation, nausea and vomiting, coughing, pain, recall, satisfaction, vocal cord movement, or Lidocaine use. However Dexmedetomidine led to quite a significant delay in post-anesthesia discharge criteria and discharge time, also a well described feature of this agent.

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Perioperative Atrial Fibrillation in Cardiac Surgery

A practice advisory is issued from cardiovascular anesthesiologists for the prophylaxis and treatment of perioperative atrial fibrillation, which has an occurrence of 30 – 50% in this population.

They review such strategies as Beta-Blockers, Amiodarone, cardioversion, Calcium Channel Blockers, Vernakalant, Colchicine etc.

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Recommendations table

Electroencephalographic density spectral array monitoring

Electroencephalographic density spectral array monitoring is employed to facilitate analysis of raw unprocessed EEG signals and this study showed correlation in young children with end tidal sevoflurane concentrations. The implications are that it may be of value in different ways for monitoring depth of anesthesia and perhaps preventing anesthesia overdose in the vulnerable developing brain

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Antimicrobials and ICU Delirium

This study enrolled non-neurological critically ill adults from a medical or surgical intensive care unit (ICU) with daily follow-up to 30 days; the independent variable was exposure to previous-day antimicrobial class: beta-lactams (subclasses: penicillins, first- to third-generation cephalosporins, fourth-generation cephalosporins, and carbapenems), macrolides, fluoroquinolones, and other.

The findings were: “First-, second-, and third-generation cephalosporins doubled the odds of delirium after baseline co-morbidities, ICU type, the course of critical care, and other competing antimicrobial and psychotropic medication risks were adjusted for. We did not find an association between delirium and cefepime, penicillins, carbapenems, fluoroquinolones, or macrolides”. 

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