A systematic review of intravenous ketamine for postoperative analgesia

Recommendations from the Italian intersociety consensus on Perioperative Anesthesa Care in Thoracic surgery (PACTS) part 2: intraoperative and postoperative care

Introduction

Anesthetic care in patients undergoing thoracic surgery presents specific challenges that require a multidisciplinary approach to management. There remains a need for standardized, evidence-based, continuously updated guidelines for perioperative care in these patients.

Methods

A multidisciplinary expert group, the Perioperative Anesthesia in Thoracic Surgery (PACTS) group, was established to develop recommendations for anesthesia practice in patients undergoing elective lung resection for lung cancer. The project addressed three key areas: preoperative patient assessment and preparation, intraoperative management (surgical and anesthesiologic care), and postoperative care and discharge. A series of clinical questions was developed, and literature searches were performed to inform discussions around these areas, leading to the development of 69 recommendations. The quality of evidence and strength of recommendations were graded using the United States Preventive Services Task Force criteria.

Results

Recommendations for intraoperative care focus on airway management, and monitoring of vital signs, hemodynamics, blood gases, neuromuscular blockade, and depth of anesthesia. Recommendations for postoperative care focus on the provision of multimodal analgesia, intensive care unit (ICU) care, and specific measures such as chest drainage, mobilization, noninvasive ventilation, and atrial fibrillation prophylaxis.

Conclusions

These recommendations should help clinicians to improve intraoperative and postoperative management, and thereby achieve better postoperative outcomes in thoracic surgery patients. Further refinement of the recommendations can be anticipated as the literature continues to evolve.

Analgesic efficacy of ketamine and magnesium after laparoscopic sleeve gastrectomy: A randomized, double-blind, placebo-controlled trial

Background Ketamine and magnesium are antagonists of the N-methyl-d-aspartate receptor, and are valuable adjuvants for multimodal analgesia and opioid sparing. Data are limited regarding the opioid sparing efficacy of the combined intraoperative application of these agents in laparoscopic bariatric surgery. The objective of this study was to compare the postoperative opioid sparing properties of a single intraoperative dose of ketamine versus a combination of single doses of ketamine and magnesium after laparoscopic gastric sleeve resection in bariatric patients. Methods One hundred and twenty- six patients were randomly assigned to receive single boluses of ketamine alone 0.5 mg kg^-1 IV (ketamine group); combined ketamine bolus of 0.5 mg kg^-1 IV and magnesium 2 g IV (ketamine and magnesium group); or placebo. Opioid consumption at 24 h (in morphine equivalents); pain at rest; postoperative nausea and vomiting impact score; sedation scores; and trends of transcutaneous carbon-di-oxide values were analysed. Results The median (inter-quartile range [range]) morphine consumption at 24 h were 32 (24-47 [4.8-91]) mg in the ketamine group, 37 (18-53 [1-144]) mg in the ketamine and magnesium group, and 26 (21-36 [5-89]) mg in the control group and were not significantly different between the groups. There were no differences for all other outcomes examined. Conclusion Combined single intraoperative bolus doses of ketamine and magnesium did not result in postoperative opioid sparing after laparoscopic gastric sleeve resection.

Analgesic effect of perioperative ketamine for total hip arthroplasties and total knee arthroplasties: A PRISMA-compliant meta-analysis

BACKGROUND

Total hip arthroplasties (THA) and total knee arthroplasties (TKA) are always associated with a frequent incidence of postoperative pain. Effective pain management after surgery is quite essential for surgeons and patients. The purpose of the present meta-analysis is to evaluate the analgesic effect of perioperative ketamine after THA and TKA.

METHODS

Seven online databases, Embase, Cochrane Library, Pubmed, Web of Science, China National Knowledge Infrastructure (CNKI), China Biomedical Literature Database (CBM), and Wanfang Data were searched for the related randomized controlled trials (RCT) by August 15, 2019. The qualities of the included studies were assessed based on the Cochrane Handbook for Systematic Reviews of Interventions 5.0. The visual analog scale (VAS), morphine equivalent consumption, and the side effects were used to evaluate the postoperative analgesic effect of ketamine by meta-analysis, which was performed by Review Manager version 5.3 software.

RESULTS

The VAS scores at 6 hours, 12 hours, 24 hours, and 48 hours after surgery were statistically lower in the ketamine group. The morphine equivalent consumptions in 24 hours and 48 hours after surgery were also significantly lower in the ketamine group. For the side effects, no statistical differences in odds ratio (OR) of sedation, dizziness, hallucination, sweating, pruritus, urinary retention, constipation, version trouble, nightmares, and delirium were observed between the ketamine group and the control group. But postoperative nausea and vomiting (PONV) showed lower OR in the ketamine group.

CONCLUSION

The present meta-analysis demonstrated perioperative ketamine could be used as a safe and effective analgesic agent for THA and TKA.

Optimal Sedation and Pain Management: A Patient- and Symptom-Oriented Paradigm

In the critically ill patient, optimal pain and sedation management remains the cornerstone of achieving comfort, safety, and to facilitate complex life support interventions. Pain relief, using multimodal analgesia, is an integral component of any orchestrated approach to achieve clinically appropriate goals in critically ill patients. Sedative management, however, remains a significant challenge. Subsequent studies including most recent randomized trials have failed to provide strong evidence in favor of a sedative agent, a mode of sedation or ancillary protocols such as sedative interruption and sedative minimization. In addition, clinical practice guidelines, despite a comprehensive evaluation of relevant literature, have limitations when applied to individual patients. These limitations have been most apparent during the coronavirus disease 2019 pandemic. As such, there is a need for a mindset shift to a practical and achievable sedation strategy, driven by patients' characteristics and individual patient needs, rather than one cocktail for all patients. In this review, we present key principles to achieve patient-and symptom-oriented optimal analgesia and sedation in the critically ill patients. Sedative intensity should be proportionate to care complexity with due consideration to an individual patient's modifiers. The use of multimodal analgesics, sedatives, and antipsychotics agents-that are easily titratable-reduces the overall quantum of sedatives and opioids, and reduces the risk of adverse events while maximizing clinical benefits. In addition, critical considerations regarding the choice of sedative agents should be given to factors such as age, medical versus operative diagnosis, and cardiovascular status. Specific populations such as trauma, neurological injury, and pregnancy should also be taken into account to maximize efficacy and reduce adverse events.

Does central sensitization affect hyperalgesia after staged bilateral total knee arthroplasty? A randomized controlled trial

Objective

Osteoarthritis (OA) patients who undergo staged bilateral total knee arthroplasty (TKA) feel postoperative hyperalgesia in the second operated knee compared with the first knee. Ketamine is an important drug for central temporal summation and inhibition of secondary mechanical hyperalgesia. This study investigated whether central sensitization has a significant effect on hyperalgesia after consecutive operations.

Methods

Seventy-one of 80 OA patients were randomly allocated to the ketamine or saline group. A bolus of ketamine (group K) or saline (group C) (0.5 mg/kg) was injected before induction and at an infusion rate of 3 µg/kg/minute during surgery. A visual analog scale (VAS) was used to assess resting and moving pain and opioid consumption on postoperative days 1, 2, and 3.

Results

The difference in the VAS score between stages 1 and 2 (D_V2-V1) was higher in the ketamine compared with the saline group. D_V2-V1 for movement between the two groups was not inferior for all periods. Ketamine did not show a large analgesic effect on second-operated knee hyperalgesia in staged bilateral TKAs.

Conclusions

We could not confirm that hyperalgesia was only related to central sensitization with low-dose ketamine. Other factors might be also associated with the hyperexcitability of nociceptive stimuli.

Clinical Research Information Service (CRIS) trial registry no: KCT0001481

Ketamine potentiates TRPV1 receptor signaling in the peripheral nociceptive pathways

TRPV1 is a cation channel expressed in peripheral nociceptive pathways and its activation can trigger nociception signals to the brain. Ketamine is an intravenous anesthetic routinely used for anesthesia induction and with potent analgesic activity. Despite its proven depressant action on peripheral sensory pathways, the relationship between ketamine and TRPV1 receptors is still unclear. In this study, we evaluated the effect of ketamine injected peripherally in a rat model of spontaneous pain induced by capsaicin. We also investigated the effect of ketamine on Ca²⁺ transients in cultured dorsal root ganglia (DRG) neurons and HEK293 cells expressing the TRPV1 receptor (HEK-TRPV1 cells). Intraplantar administration of ketamine caused an unexpected increase in nocifensive behavior induced by capsaicin. Incubation of HEK-TRPV1 cells with 10 μM ketamine increased TRPV1 and PKCє phosphorylation. Ketamine potentiated capsaicin-induced Ca²⁺ transients in HEK-TRPV1 cells and DRG neurons. Ketamine also prevented TRPV1 receptor desensitization induced by successive applications of capsaicin. єV1-2, a PKCє inhibitor, reduced potentiation of capsaicin-induced Ca²⁺ transients by ketamine. Taken together, our data indicate that ketamine potentiates TRPV1 receptor sensitivity to capsaicin through a mechanism dependent on PKCє activity.

Essential elements of anaesthesia practice in ERAS programs

PURPOSE

Enhanced recovery pathways vary amongst institutions but include key components for anesthesiologists, such as haemodynamic optimization, use of short-acting drugs (and monitoring), postoperative nausea and vomiting (PONV) prophylaxis, protective ventilation, and opioid-sparing multimodal analgesia.

METHODS

After critical appraisal of the literature, studies were selected with particular attention being paid to meta-analyses, randomized controlled trials, and large prospective cohort studies. For each item of the perioperative treatment pathway, available English literature was examined and reviewed.

RESULTS

Patients should be permitted to drink clear fluids up to 2 h before anaesthesia and surgery. Oral carbohydrate loading should be used routinely. All patients may have an individualized plan for fluid and haemodynamic management that matches the monitoring needs with patient and surgical risk. Minimizing the side effects of anaesthetics and analgesics using short-acting drugs with careful perioperative monitoring should be encouraged. Protective ventilation with alveolar recruitment maneuvers is required. Preventive use of a combination with 2-3 antiemetics in addition to propofol-based total intravenous anaesthesia (TIVA) is most likely to reduce PONV. While the ideal analgesia regimen remains to be determined, it is clear that a multimodal opioid-sparing analgesic strategy has significant benefits.

CONCLUSION

Careful evaluation of single patient and planning of the anesthetic care are mandatory to join the ERAS philosophy. Optimal fluid management, use of short-acting drugs, prevention of PONV, protective ventilation, and multimodal analgesia are the cornerstones of the anaesthesia management within ERAS protocols.

Enhanced Recovery and Surgical Optimization Protocol for Minimally Invasive Gynecologic Surgery: An AAGL White Paper

This is the first Enhanced Recovery After Surgery (ERAS) guideline dedicated to standardizing and optimizing perioperative care for women undergoing minimally invasive gynecologic surgery. The guideline was rigorously formulated by an American Association of Gynecologic Laparoscopists Task Force of US and Canadian gynecologic surgeons with special interest and experience in adapting ERAS practices for patients requiring minimally invasive gynecologic surgery. It builds on the 2016 ERAS Society recommendations for perioperative care in gynecologic/oncologic surgery by serving as a more comprehensive reference for minimally invasive endoscopic and vaginal surgery for both benign and malignant gynecologic conditions. For example, the section on preoperative optimization provides more specific recommendations derived from the ambulatory surgery and anesthesia literature for the management of anemia, hyperglycemia, and obstructive sleep apnea. Recommendations pertaining to multimodal analgesia account for the recent Food and Drug Administration warnings about respiratory depression from gabapentinoids. The guideline focuses on workflows important to high-value care in minimally invasive surgery, such as same-day discharge, and tackles controversial issues in minimally invasive surgery, such as thromboprophylaxis. In these ways, the guideline supports the American Association of Gynecologic Laparoscopists and our collective mission to elevate the quality and safety of healthcare for women through excellence in clinical practice.

Multimorbidity and Critical Care Neurosurgery: Minimizing Major Perioperative Cardiopulmonary Complications

With increasing prevalence of chronic diseases, multimorbid patients have become commonplace in the neurosurgical intensive care unit (neuro-ICU), offering unique management challenges. By reducing physiological reserve and interacting with one another, chronic comorbidities pose a greatly enhanced risk of major postoperative medical complications, especially cardiopulmonary complications, which ultimately exert a negative impact on neurosurgical outcomes. These premises underscore the importance of perioperative optimization, in turn requiring a thorough preoperative risk stratification, a basic understanding of a multimorbid patient’s deranged physiology and a proper appreciation of the potential of surgery, anesthesia and neurocritical care interventions to exacerbate comorbid pathophysiologies. This knowledge enables neurosurgeons, neuroanesthesiologists and neurointensivists to function with a heightened level of vigilance in the care of these high-risk patients and can inform the perioperative neuro-ICU management with individualized strategies able to minimize the risk of untoward outcomes. This review highlights potential pitfalls in the intra- and postoperative neuro-ICU period, describes common preoperative risk stratification tools and discusses tailored perioperative ICU management strategies in multimorbid neurosurgical patients, with a special focus on approaches geared toward the minimization of postoperative cardiopulmonary complications and unplanned reintubation.

Chronic Pain After Lung Resection: Risk Factors, Neuropathic Pain, and Quality of Life

CONTEXT

Chronic postsurgical pain (CPSP) can occur frequently after thoracic surgery.

OBJECTIVES

This retrospective study aimed to determine CPSP prevalence, risk factors, neuropathic pain (NP) occurrence, and its impact on quality of life.

METHODS

About 200 patients who underwent lung resection via minithoracotomy or thoracoscopy between January 2017 and December 2017 were assessed 4-12 months postoperatively via phone interview for chronic pain by a 0-10 Numeric Rating Scale, for NP using the Douleur Neuropathique 4 test, and for quality of life using a Short Form-36 (SF-36) Health Survey (Italian version).

RESULTS

CPSP incidence was 35% (n = 70 of 200; 95% CI 41-28) of which 31.5% (n = 22 of 70; 95% CI 41-21) was with NP. Only 10% of patients with CPSP reported severe chronic pain. According to univariate analysis, CPSP was associated to moderate and severe acute postoperative pain (P < 0.001), open surgery (P = 0.001), and female gender (P = 0.044). According to multivariable analysis, independent risk factors for CPSP development included moderate-to-severe acute postoperative pain occurrence (odds ratio 32.61; 95% CI 13.37-79.54; P < 0.001) and open surgery (odds ratio 6.78; 95% CI, 2.18-21.03; P = 0.001). NP incidence was higher in female patients (16% in women and 6% in men, respectively; P = 0.040). A significant decrease in all SF-36 Health Survey domain scores was recorded for patients with CPSP and NP (P < 0.001).

CONCLUSION

More than one of three patients who underwent lung resection could develop CPSP, frequently showing neuropathic component. Female gender reported a higher CPSP and NP incidence. Moderate-to-severe acute postoperative pain occurrence and open surgery seem to be independent risk factors for CPSP. Chronic pain and NP have a negative impact on quality of life, decreasing the SF-36 scores of all domains.

Nonenteral Pain Management

Otolaryngologic surgeries present challenges to ensuring postoperative pain control owing to their location and nature that may require patients to be NPO for long periods of time, making enteral medication administration difficult or impossible. There are several alternative administration routes to bypass the gastrointestinal tract, including intravenous, transdermal, subcutaneous, and rectal. Options exist for opioid administration in the perioperative setting, including intravenous boluses, patient controlled analgesia, and transdermal patches. Acetaminophen, nonsteroidal anti-inflammatory drugs, and ketamine exist in nonenteral formulations. When applied in a multimodal strategy, nonenteral medications can provide appropriate analgesia, reduce opioid consumption, and increase patient satisfaction.

Intravenous Lidocaine for Acute Pain: A Single-Institution Retrospective Study

BACKGROUND

In the perioperative period, intravenous lidocaine has been used as an opioid-sparing systemic analgesic with additional anti-inflammatory and anti-hyperalgesic properties.

OBJECTIVE

The aim of this retrospective study was to review the utilization, efficacy, and safety of intravenous lidocaine on our Acute Pain Service (APS) and identify surgical and patient populations where this intervention was found to be useful.

PATIENTS AND METHODS

This retrospective study was designed to assess acute pain management in patients who received an intravenous lidocaine infusion between February 2013 and December 2017. Data collected included demographics, surgery type, infusion duration, pain scores, analgesic consumption, and adverse effects. Pain scores included rest and active pain scores and were analyzed by surgical model and subgroups. Clinically important differences (CIDs) in pain were determined by changes in pain score difference of ≥ 2 (11-point scale) or ≥ 30% reduction in pain intensity. A patient was considered to have a true CID if a CID was observed with rest and/or active pain scores at both first to second (4-24 h) and first to final time point (4 h to infusion end) comparisons.

RESULTS

In total, 544 patients received intravenous lidocaine during this period, and 394 were included in the final analysis. The average (± standard deviation) duration of infusion was 68.60 ± 49.52 h. Surgical specialties included gastrointestinal surgery (41%), orthopedics (28%), neurosurgery (15%), vascular surgery (10%), and others (6%). Overall, 56.1% of the study population experienced a CID, with reduced pain scores at rest and/or with activity. CIDs were also observed in patients with chronic pain (53.5%) and when intravenous lidocaine was used as a rescue technique (69.6%). Within the rescue cohort, opioid-dependent and opioid-naïve patients experienced 23.0% and 45.6% reductions, respectively, in their 8-h intravenous opioid consumption. In total, 37 patients in the study experienced transient signs of mild local anesthetic toxicity, which resolved with infusion titration (conservative) management. One serious adverse event required intervention, and the patient was successfully resuscitated.

CONCLUSIONS

This retrospective study at a single institution with an APS policy for intravenous lidocaine in the postoperative period identifies benefits of intravenous lidocaine in certain surgical and patient populations. The findings need to be confirmed with further research.

Neuroanesthesia Guidelines for Optimizing Transcranial Motor Evoked Potential Neuromonitoring During Deformity and Complex Spinal Surgery: A Delphi Consensus Study

STUDY DESIGN

Expert opinion-modified Delphi study.

OBJECTIVE

We used a modified Delphi approach to obtain consensus among leading spinal deformity surgeons and their neuroanesthesiology teams regarding optimal practices for obtaining reliable motor evoked potential (MEP) signals.

SUMMARY OF BACKGROUND DATA

Intraoperative neurophysiological monitoring of transcranial MEPs provides the best method for assessing spinal cord integrity during complex spinal surgeries. MEPs are affected by pharmacological and physiological parameters. It is the responsibility of the spine surgeon and neuroanesthesia team to understand how they can best maintain high-quality MEP signals throughout surgery. Nevertheless, varying approaches to neuroanesthesia are seen in clinical practice.

METHODS

We identified 19 international expert spinal deformity treatment teams. A modified Delphi process with two rounds of surveying was performed. Greater than 50% agreement on the final statements was considered "agreement"; >75% agreement was considered "consensus."

RESULTS

Anesthesia regimens and protocols were obtained from the expert centers. There was a large amount of variability among centers. Two rounds of consensus surveying were performed, and all centers participated in both rounds of surveying. Consensus was obtained for 12 of 15 statements, and majority agreement was obtained for two of the remaining statements. Total intravenous anesthesia was identified as the preferred method of maintenance, with few centers allowing for low mean alveolar concentration of inhaled anesthetic. Most centers advocated for <150 μg/kg/min of propofol with titration to the lowest dose that maintains appropriate anesthesia depth based on awareness monitoring. Use of adjuvant intravenous anesthetics, including ketamine, low-dose dexmedetomidine, and lidocaine, may help to reduce propofol requirements without negatively effecting MEP signals.

CONCLUSION

Spine surgeons and neuroanesthesia teams should be familiar with methods for optimizing MEPs during deformity and complex spinal cases. Although variability in practices exists, there is consensus among international spinal deformity treatment centers regarding best practices.

LEVEL OF EVIDENCE

5.

Effects of Intraoperative Ketamine on Post-Operative Recovery in Obstructive Sleep Apnea Patients: A Case-Control Study

Objective

To evaluate the post-operative outcomes of patients with obstructive sleep apnea (OSA) given intraoperative ketamine.

Design: case-control study

A total of 574 patients (287 received ketamine and 287 were matched controls) diagnosed with OSA and body mass index (BMI) > 30 who received general anesthesia were included in this study. Patients given intraoperative ketamine were matched (1:1) with those who did not receive ketamine for age, gender, BMI, ethnicity, anesthesia time, intraoperative fentanyl dose, ketamine dose, and surgery type. A sub-analysis was performed based on the dose of ketamine administered and also on the surgery type. Measured outcomes include post-operative pain scores, post-operative opioid requirements, respiratory status, oxygen use, and duration post-operatively.

Results

Intraoperative ketamine use did not decrease pain scores or post-operative opioid use when compared with the control (no intraoperative ketamine) group. Patients who received high-dose ketamine had significantly higher post-operative pain scores (p=0.048) while in the post-anesthesia care unit (PACU) and required supplemental oxygen for a longer period of time (p = 0.030), pain scores were not significant for patients who underwent orthopedic/spine procedures (p = 0.074), and high-dose ketamine group patients who underwent orthopedic/spine surgery required significantly more opioids in the PACU (p = 0.031). Among patients who received low-dose ketamine, those who underwent head, ear, nose, and throat surgery required significantly more opioids in PACU (p = 0.022).

Conclusions

Low-dose intraoperative ketamine did not decrease pain scores or post-operative opioid use significantly and did not improve standard respiratory recovery parameters for OSA patients after surgery. Neither low- nor high-dose ketamine demonstrated the anticipated benefits of low pain scores and reduced post-operative opioid use. These outcomes will differ depending on the surgery type and dose of ketamine used.

Overview of multimodal analgesia initiated in the perioperative setting

Despite progress in pain management in the perioperative setting, the literature is full of evidence that managing postoperative pain is suboptimal. Since the mechanism of pain is complex, the use of multimodal technique allows clinicians to use a combination of two or more drugs targeting different areas of pain transmission because of surgery. As part of enhanced recovery initiatives after surgery, healthcare and professional organisations incorporate the use of multimodal analgesia in surgical guidelines to improve patient satisfaction. This review aims to understand and summarise the current body of evidence involving the most common pharmacological therapies to manage postoperative pain in the preoperative setting.

Ketamine infusion for pain control in adult patients with multiple rib fractures: Results of a randomized control trial

BACKGROUND

Rib fractures occur in up to 40% of trauma patients and are associated with increased mortality. Opiate-based pain regimens remain the cornerstone of rib fracture management; however, concerns around opioids have fostered interest in alternative analgesics. Ketamine is currently being used in lieu of opioids, but little evidence exists supporting its use within the trauma population.

METHODS

A prospective, randomized, double-blind placebo-controlled trial of adult patients with three or more rib fractures admitted to a Level I trauma center was conducted. Exclusion criteria included age older than 64 years, Glasgow Coma Scale score less than 13, and chronic opiate use. The experimental arm received low-dose ketamine (LDK) at 2.5 μg·kg·min while the placebo cohort received an equivalent rate of 0.9% normal saline. All infusions were continued for 48 hours. The primary outcome was reduction in numeric pain score (NPS) during the first 24 hours. Secondary outcomes studied included oral morphine equivalent (OME) utilization, length of stay, epidural rates, pulmonary complications, and adverse events.

RESULTS

Forty-five (49%) of 91 patients were randomized to the experimental arm. Both groups were similar in makeup. Overall, 74.7% were male, had a median age of 49 years, and an Injury Severity Score (ISS) of 14. Low-dose ketamine was not associated with a significant reduction in 24-hour NPS or OME totals. Subgroup analysis of 45 severely injured patients (ISS, >15) demonstrated that LDK was associated with a significant reduction in OME utilization during the first 24 hours (35.7 vs. 68, p = 0.03), 24 hours to 48 hours (64.2 vs. 96, p = 0.03), and overall (152.1 vs. 198, p = 0.048). No difference in other secondary outcomes or adverse events was noted.

CONCLUSION

Low-dose ketamine failed to decrease NPS or OME within the overall cohort, but a decrease in OME was observed among patients with an ISS greater than 15. Confirmatory studies are necessary to determine if LDK is a useful adjunct among severely injured patients.

LEVEL OF EVIDENCE

Therapeutic study, level II.

Ketamine Blocks Morphine-Induced Conditioned Place Preference and Anxiety-Like Behaviors in Mice

Patients suffering from opioid use disorder often relapse during periods of abstinence, which is posited to be caused by negative affective states that drive motivated behaviors. Here, we explored whether conditioning mice with morphine in a conditioned place preference (CPP) training paradigm evoked anxiety-like behavior during morphine abstinence. To do this, mice were conditioned with morphine (10 mg/kg, i.p.) for 5 days. Twenty-four hours following conditioning, anxiety levels were tested by measuring time in the open arms of the elevated plus-maze. The next day, mice were placed in the three-compartment chamber to measure morphine-induced CPP. Our results show that following morphine conditioning, mice spent significantly less time in the open arm of the elevated plus-maze and expressed robust morphine CPP on CPP test day. Furthermore, we found that an acute treatment with (R,S)-ketamine (10 mg/kg, i.p.), a medication demonstrating promise for preventing anxiety-related phenotypes, 30 min before testing on post-conditioning day 1, increased time spent in the open arm of the elevated plus-maze in saline- and morphine-conditioned mice. Additionally, we found that the second injection of ketamine 30 min before CPP tests on post-conditioning day 2 prevented morphine-induced CPP, which lasted for up to 28 days post-conditioning. Furthermore, we found that conditioning mice with 10% (w/v) sucrose using an oral self-administration procedure did not evoke anxiety-like behavior, but elicited robust CPP, which was attenuated by ketamine treatment 30 min before CPP tests. Overall, our results suggest that the ketamine-induced block of morphine CPP may not be attributed solely to alleviating negative affective states, but potentially through impaired memory of morphine-context associations.

Multimodal Analgesic Regimen for Spine Surgery

Background

Various multimodal analgesic approaches have been proposed for spine surgery. The authors evaluated the effect of using a combination of four nonopioid analgesics versus placebo on Quality of Recovery, postoperative opioid consumption, and pain scores.

Methods

Adults having multilevel spine surgery who were at high risk for postoperative pain were double-blind randomized to placebos or the combination of single preoperative oral doses of acetaminophen 1,000 mg and gabapentin 600 mg, an infusion of ketamine 5 µg/kg/min throughout surgery, and an infusion of lidocaine 1.5 mg/kg/h intraoperatively and during the initial hour of recovery. Postoperative analgesia included acetaminophen, gabapentin, and opioids. The primary outcome was the Quality of Recovery 15-questionnaire (0 to 150 points, with 15% considered to be a clinically important difference) assessed on the third postoperative day. Secondary outcomes were opioid use in morphine equivalents (with 20% considered to be a clinically important change) and verbal-response pain scores (0 to 10, with a 1-point change considered important) over the initial postoperative 48 h.

Results

The trial was stopped early for futility per a priori guidelines. The average duration ± SD of surgery was 5.4 ± 2.1 h. The mean ± SD Quality of Recovery score was 109 ± 25 in the pathway patients (n = 150) versus 109 ± 23 in the placebo group (n = 149); estimated difference in means was 0 (95% CI, –6 to 6, P = 0.920). Pain management within the initial 48 postoperative hours was not superior in analgesic pathway group: 48-h opioid consumption median (Q1, Q3) was 72 (48, 113) mg in the analgesic pathway group and 75 (50, 152) mg in the placebo group, with the difference in medians being –9 (97.5% CI, –23 to 5, P = 0.175) mg. Mean 48-h pain scores were 4.8 ± 1.8 in the analgesic pathway group versus 5.2 ± 1.9 in the placebo group, with the difference in means being –0.4 (97.5% CI; –0.8, 0.1, P = 0.094).

Conclusions

An analgesic pathway based on preoperative acetaminophen and gabapentin, combined with intraoperative infusions of lidocaine and ketamine, did not improve recovery in patients who had multilevel spine surgery.

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Effect of ketamine on the NeuroSENSE WAVCNS during propofol anesthesia; a randomized feasibility trial

Dose-dependent effects of ketamine on processed electroencephalographic depth-of-hypnosis indices have been reported. Limited data are available for the NeuroSENSE WAV_CNS index. Our aim was to establish the feasibility of closed-loop propofol-remifentanil anesthesia guided by the WAV_CNS index in the presence of an analgesic dose of ketamine. Thirty ASA I-II adults, 18-54 years, requiring general anesthesia for anterior cruciate ligament surgery were randomized to receive: full-dose [ketamine, 0.5 mg kg^-1 initial bolus, 10 mcg kg^-1 min^-1 infusion] (recommended dose for postoperative pain management); half-dose [ketamine, 0.25 mg kg^-1 bolus, 5 mcg kg^-1 min^-1 infusion]; or control [no ketamine]. After the ketamine bolus, patients received 1.0 mcg kg^-1 remifentanil over 30 s, then 1.5 mg kg^-1 propofol over 30 s, followed by manually-adjusted propofol-remifentanil anesthesia. The WAV_CNS was > 60 for 7/9 patients in the full-dose group at 7 min after starting the propofol infusion. This was inconsistent with clinical observations of depth-of-hypnosis and significantly higher than control (median difference [MD] 17.0, 95% confidence interval [CI] 11.4-26.8). WAV_CNS was median [interquartile range] 49.3 [42.2-62.6] in the half-dose group, and not different to control (MD 5.1, 95% CI - 4.9 to 17.9). During maintenance of anesthesia, the WAV_CNS was higher in the full-dose group compared to control (MD 14.7, 95% CI 10.2-19.2) and in the half-dose group compared to control (MD 11.4, 95% CI 4.7-20.4). The full-dose of ketamine recommended for postoperative pain management had a significant effect on the WAV_CNS. This effect should be considered when using the WAV_CNS to guide propofol-remifentanil dosing.Trial Registration ClinicalTrails.gov No. NCT02908945.

Pain Intensity in the First 96 Hours After Abdominal Surgery: A Prospective Cohort Study

OBJECTIVE

Multimodal pain management strategies aim to improve postoperative pain control. The purpose of this study was to analyze pain scores and risk factors for acute postoperative pain after various abdominal surgery procedures.

METHODS

Data on 11 different abdominal surgery procedures were prospectively recorded. Pain intensity (rest, mobilization) and patient satisfaction at discharge were assessed using a visual analog scale (VAS; 0-10), and analgesic consumption was recorded until 96 hours postoperation. Demographic, surgery-related, and pain management-related univariate risk factors for insufficient pain control (VAS ≥ 4) were entered in a multivariate logistic regression model.

RESULTS

A total of 1,278 patients were included. Overall, mean VAS scores were <3 at all time points, and scores at mobilization were consistently higher than at rest (P < 0.05). Thirty percent of patients presented a prolonged VAS score ≥4 at mobilization at 24 hours, significantly higher than at rest (14%, P < 0.05). High pain scores correlated with high opioid consumption, whereas a variability of pain scores was observed in patients with low opioid consumption. The only independent risk factor for moderate and severe pain (VAS ≥ 4) was younger age (<70 years, P = 0.001). The mean satisfaction score was 8.18 ± 1.29.

CONCLUSIONS

Among 1,278 patients, pain was controlled adequately during the first four postoperative days, resulting in high levels of patient satisfaction. Pain levels were higher at mobilization. Younger age was the only independent risk factor for insufficient pain control. Preventive treatment in patients <70 years old and before mobilization could be evaluated for potential improvement.

A review on the recent application of ketamine in management of anesthesia, pain, and health care

Ketamine is considered as a promising drug for many clinical applications even after five decades since its discovery. Ketamine is a dissociative anesthetic agent with a variety of pharmacological effects from anesthetic induction and maintenance to analgesic and sedative depending on the consuming dose. It can be used solely or in combination with other co-adjuvant drugs, increasing their efficacy. Many therapeutic properties of ketamine have been attributed to its antagonism mechanism to N-Methyl-D-aspartate receptor. Identifying new properties of ketamine such as neuroprotective, antiinflammatory, and antitumor effects, on one hand, and taking advantage of subanesthetic regimens of ketamine, on the other hand, have resulted in a widespread use of ketamine in various clinical applications. Ketamine is solvable in aqueous and lipid solutions, providing convenient administration via multiple routes, including oral, nasal, rectal, intravenous, intramuscular, subcutaneous, transdermal, sublingual, and intraosseous administration. Application of ketamine has some advantages over other sedative and anesthetic agents. It produces bronchodilation status, allowing for most secure induction of anesthesia in patients with life-threatening asthma and intense acute bronchial constriction. Ketamine has an excellent hemodynamic profile, makes it the agent of choice for patients with unstable hemodynamics, such as shocked or hypotensive patients. Ketamine usage has been associated with a lower risk of respiratory depression and relatively more conserved airway reflexes. Although being an anesthetic agent, ketamine has been increasingly used in subanesthetic doses for acute and chronic pain as well as depression. Using ketamine in pre and postoperative pain management is well established. However, the studies on ketamine performance in pain management demonstrated contradicting results. On the other hand, various side effects along with no confirmatory data on long-term treatment demand great caution when using ketamine for treating complex chronic pains. The present study aimed to provide a general review on the recent applications of ketamine in anesthesia, pain management, and critical care.

Postoperative Pain and Analgesic Requirements in the First Year after Intraoperative Methadone for Complex Spine and Cardiac Surgery

BACKGROUND

Methadone is a long-acting opioid that has been reported to reduce postoperative pain scores and analgesic requirements and may attenuate development of chronic postsurgical pain. The aim of this secondary analysis of two previous trials was to follow up with patients who had received a single intraoperative dose of either methadone or traditional opioids for complex spine or cardiac surgical procedures.

METHODS

Preplanned analyses of long-term outcomes were conducted for spinal surgery patients randomized to receive 0.2 mg/kg methadone at the start of surgery or 2 mg hydromorphone at surgical closure, and for cardiac surgery patients randomized to receive 0.3 mg/kg methadone or 12 μg/kg fentanyl intraoperatively. A pain questionnaire assessing the weekly frequency (the primary outcome) and intensity of pain was mailed to subjects 1, 3, 6, and 12 months after surgery. Ordinal data were compared with the Mann-Whitney U test, and nominal data were compared using the chi-square test or Fisher exact probability test. The criterion for rejection of the null hypothesis was P < 0.01.

RESULTS

Three months after surgery, patients randomized to receive methadone for spine procedures reported the weekly frequency of chronic pain was less (median score 0 on a 0 to 4 scale [less than once a week] vs. 3 [daily] in the hydromorphone group, P = 0.004). Patients randomized to receive methadone for cardiac surgery reported the frequency of postsurgical pain was less at 1 month (median score 0) than it was in patients randomized to receive fentanyl (median score 2 [twice per week], P = 0.004).

CONCLUSIONS

Analgesic benefits of a single dose of intraoperative methadone were observed during the first 3 months after spinal surgery (but not at 6 and 12 months), and during the first month after cardiac surgery, when the intensity and frequency of pain were the greatest.

Evaluation of Clinical Factors Associated with Adverse Drug Events in Patients Receiving Sub-Anesthetic Ketamine Infusions

Introduction

Sub-anesthetic ketamine is frequently used as an analgesic to reduce perioperative opioid consumption and has also been shown to have antidepressant effects. Side effects of ketamine include dizziness, diplopia, nystagmus, and psychomimetic effects. It is unclear what clinical factors may be associated with ketamine-related adverse drug events (ADEs).

Methods

We performed a retrospective review of 95 patients who received sub-anesthetic ketamine infusions at our institution. Data examined associations between ketamine-related ADEs and various clinical characteristics including chronic pain, depression, or psychiatric disorder, patient physical characteristics, chronic opioid use, perioperative opioid use, dose and duration of ketamine infusions, pain scores, and perioperative medications such as serotonergic agents, central nervous system (CNS) depressants, and analgesics.

Results

Overall incidence of ketamine-related ADEs was 29.5% and the incidence of psychomimetic effects was 14.8%. We observed that patients with a history of depression have a lower incidence of ketamine-related ADEs compared to patients without a history of depression (10.3% vs 37.3%; p value = 0.007).

Conclusion

Patients with depression were found to have a statistically significant reduction in the incidence of ketamine-related ADEs. We found no statistically significant positive associations between ketamine-related ADEs and other clinical factors such as a history of chronic pain, psychiatric disease, patient physical characteristics, perioperative opioid use, dose of ketamine infusion, or co-administration of other CNS depressants.

Pharmacokinetics and Safety of Esketamine in Chinese Patients Undergoing Painless Gastroscopy in Comparison with Ketamine: A Randomized, Open-Label Clinical Study

Purpose

To assess the pharmacokinetics and safety of pure S-ketamine (esketamine) in Chinese patients undergoing painless gastroscopy and evaluate the potential advantage of esketamine in clinical treatment compared with racemate ketamine hydrochloride injection.

Patients and methods

A randomized, open-label, parallel-controlled, Phase I study was performed with 32 patients undergoing painless gastroscopy. Patients received a single dose of esketamine (0.5 mg/kg) or racemic ketamine (1 mg/kg, esketamine:R-ketamine=1:1), injected in 10 s. Blood samples were collected for pharmacokinetic analysis. The concentrations of esketamine, R-ketamine, S-norketamine, and R-norketamine were measured with a validated liquid chromatography with tandem mass spectrometry (LC-MS/MS) method.

Results

After administering a single dose of esketamine and racemate ketamine, the pharmacokinetics parameters of esketamine and S-norketamine are both similar in treatment groups. The clearance of esketamine in two groups was 18.1±3.2 and 18.4±3.4 mL/min•kg, respectively. However, in the ketamine group, esketamine has a larger clearance than R-ketamine (18.4±3.4 mL/min·kg vs 15.8±3.1 mL/min·kg, P<0.001). Further analysis showed that gender did not affect the pharmacokinetics of esketamine and racemate ketamine. Regarding the safety of esketamine and racemate ketamine, no serious adverse events were observed during treatment, and the incidences of adverse events were 75.0% (esketamine) and 87.5% (racemate ketamine). The main adverse reactions were dizziness, agitation, nausea, vomiting, headache, and fatigue. However, compared with racemic ketamine, esketamine offers a shorter recovery time (9 mins vs. 13 mins, P<0.05) and orientation recovery time (11.5 mins vs. 17 mins, P<0.05) after short anesthesia.

Conclusion

Esketamine administration as a single dose of 0.5 mg/kg was generally safe and tolerated in patients undergoing painless gastroscopy. In terms of anesthesia, a relatively small dose of esketamine can be used instead of racemate ketamine for routine treatment without consideration of gender differences.

A comparison of two doses of ketamine with dexmedetomidine for fiberoptic nasotracheal intubation

Background and Aims:

Flexible fiber-optic intubation is considered to be the gold standard for management of difficult airway. Fiber-optic intubation does require effective sedation and blunting of airway reflexes for which various drug regimens have been utilized in the past. In a quest to find the noble drug combination, we combined ketamine and dexmedetomidine in two different doses, to evaluate the clinical efficacy and safety profile of ketamine and dexmedetomidine for fiber-optic intubation.

Materials and Methods:

This prospective randomized study was conducted in 72 patients of 20–50 years’ age group of either sex with the American Society of Anesthesiologists Physical Status I and II with difficult airway. We compared two doses of ketamine 20 mg (Group I) and 40 mg (Group II) with a common dose of dexmedetomidine at 1 μg/kg body weight, given as an infusion over 10 min (a solution of 50 ml with normal saline). Sedation scores, hemodynamic variables in terms of blood pressure, heart rate (HR), and oxygen saturation were studied along with 24-h postoperative patient discomfort and recall of procedure.

Results:

Group II patients showed less variation from their baseline values in terms of HR (ranged between 0.73% and 4.75%) and mean arterial pressure (ranged between 0% and 3.97%) in comparison to Group I HR (ranged between 0.09% and 9.81%) and mean pressures (ranged between 0.3% and 10.38%). Discomfort during procedure (P < 0.001) and recall of procedure scale (P = <0.001) were found significantly better/lower in Group II as compared to Group I.

Conclusion:

Ketamine 40 mg in comparison to 20 mg with dexmedetomidine provides better hemodynamic conditions with better tolerance and lower recall to the fiber-optic intubation.

The intraoperative use of non-opioid adjuvant analgesic agents: a survey of anaesthetists in Australia and New Zealand

BACKGROUND

Opioids have long been the mainstay of drugs used for intra-operative analgesia. Due to their well-known short and long term side effects, the use of non-opioid analgesics has often been encouraged to decrease the dose of opioid required and minimise these side effects. The trends in using non-opioid adjuvants among Australian Anaesthetists have not been examined before. This study has attempted to determine the use of non-opioid analgesics as part of an opioid sparing practice among anaesthetists across Australia and New Zealand.

METHODS

A survey was distributed to 985 anaesthetists in Australia and New Zealand. The questions focused on frequency of use of different adjuvants and any reasons for not using individual agents. The agents surveyed were paracetamol, dexamethasone, non-steroidal anti-inflammatory agents (NSAIDs), tramadol, ketamine, anticonvulsants, intravenous lidocaine, systemic alpha 2 agonists, magnesium sulphate, and beta blockers. Descriptive statistics were used and data are expressed as a percentage of response for each drug.

RESULTS

The response rate was 33.4%. Paracetamol was the most frequently used; with 72% of the respondents describing frequent usage (defined as usage above 70% of the time); followed by parecoxib (42% reported frequent usage) and dexamethasone (35% reported frequent usage). Other adjuvants were used much less commonly, with anaesthetists reporting their frequent usage at less than 10%. The majority of respondents suggested that they would never consider dexmedetomidine, magnesium, esmolol, pregabalin or gabapentin. Perceived disincentives for the use of analgesic adjuvants varied. The main concerns were side effects, lack of evidence for benefit, and anaesthetists' experience. The latter two were the major factors for magnesium, dexmedetomidine and esmolol.

CONCLUSION

The uptake of tramadol, lidocaine and magnesium amongst respondents from anaesthetists in Australia and New Zealand was poor. Gabapentin, pregabalin, dexmedetomidine and esmolol use was relatively rare. Most anaesthetists need substantial evidence before introducing a non-opioid adjuvant into their routine practice. Future trials should focus on assessing the opioid sparing benefits and relative risk of using individual non-opioid adjuvants in the perioperative period for specific procedures and patient populations.

An Update on the Basic and Clinical Science of Ketamine Analgesia

OBJECTIVE

In the context of the current opioid epidemic, there has been a renewed interest in the use of ketamine as an analgesic agent.

METHODS

We reviewed ketamine analgesia.

RESULTS

Ketamine is well-known as an antagonist for N-methyl-D-aspartate receptors. In addition, it can regulate the function of opioid receptors and sodium channels. Ketamine also increases signaling through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. These myriad of molecular and cellular mechanisms are responsible for a number of pharmacological functions including pain relief and mood regulation. Clinically, a number of studies have investigated the role of ketamine in the setting of acute and chronic pain, and there is evidence that ketamine can provide analgesia in a variety of pain syndromes.

DISCUSSION

In this review, we examined basic mechanisms of ketamine and its current clinical use and potential novel use in pain management.

Assessing the effectiveness of perioperative s-ketamine on new-onset headache after resective epilepsy surgery (ESPAIN-trial): protocol for a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Effective treatment of new-onset headache after craniotomy, especially anterior temporal lobectomy (ATL) and amygdalohippocampectomy for drug-resistant temporal lobe epilepsy, is a challenge. The current practice, acetaminophen combined with opioids is often reported by patients as insufficient and sometimes accompanied by opioid-related adverse effects. Based on expert opinion, anaesthesiologists therefore frequently consider s-ketamine as add-on therapy. This randomised parallel group design trial compares s-ketamine with a placebo as add on medication to a multimodal pain approach.

METHODS AND ANALYSIS

In total 62 adult participants, undergoing ATL for drug resistant epilepsy under general anaesthesia, will be randomised to either receive a 0.25 mg/kg bolus followed by a continuous infusion of 0.1 mg/kg/hour of s-ketamine or placebo (0.9% NaCl) starting before incision and continued for 48 hours as an addition to acetaminophen and opioids administered in a patient-controlled analgesia pump. The primary outcome measure is the cumulative postoperative opioid consumption. Patient recruitment started August 2018 and will end in 2021. Secondary outcome measures are postoperative pain intensity scores, psychological parameters, length of hospital stay and adverse events and will be reassessed at 3 and 6 months after surgery, with a baseline measurement preoperatively. All data are collected by researchers who are blinded to the treatment. The data will be analysed by multivariable linear mixed-effects regression.

ETHICS AND DISSEMINATION

Ethical approval has been given by the local medical ethical committee (NL61666.068.17). This study will be conducted in accordance with the Dutch Medical Research Involving Human Subjects Act and the Declaration of Helsinki. The results of this trial will be publicly disclosed and submitted for publication in an international peer-reviewed scientific journal.

TRIAL REGISTRATION NUMBER

NTR6480.

Acute Pain in Older Adults: Recommendations for Assessment and Treatment

The management of acute pain in older adults (age 65 or greater) requires special attention due to various physiologic, cognitive, functional, and social issues that may change with aging. Especially in the postoperative setting, there are significant complications that can occur if pain is not treated adequately for elderly patients. In this article, the authors describe these changes in detail and discuss how pain should be assessed appropriately in older patients. In addition, the authors detail the unique risks and benefits of several mainstream analgesic medications as well as interventional treatments for elderly patients. The authors' goal is to provide recommendations for health care providers on appropriately recognizing and treating pain in a safe, effective manner for aging patients.

Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea

The purpose of the Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea (OSA) is to present recommendations based on current scientific evidence. This guideline seeks to address questions regarding the intraoperative care of patients with OSA, including airway management, anesthetic drug and agent effects, and choice of anesthesia type. Given the paucity of high-quality studies with regard to study design and execution in this perioperative field, recommendations were to a large part developed by subject-matter experts through consensus processes, taking into account the current scientific knowledge base and quality of evidence. This guideline may not be suitable for all clinical settings and patients and is not intended to define standards of care or absolute requirements for patient care; thus, assessment of appropriateness should be made on an individualized basis. Adherence to this guideline cannot guarantee successful outcomes, but recommendations should rather aid health care professionals and institutions to formulate plans and develop protocols for the improvement of the perioperative care of patients with OSA, considering patient-related factors, interventions, and resource availability. Given the groundwork of a comprehensive systematic literature review, these recommendations reflect the current state of knowledge and its interpretation by a group of experts at the time of publication. While periodic reevaluations of literature are needed, novel scientific evidence between updates should be taken into account. Deviations in practice from the guideline may be justifiable and should not be interpreted as a basis for claims of negligence.

Local Ketamine Improves Postoperative Analgesia After Third Molar Surgery

PURPOSE

Evidence exists to support the peripheral analgesic effect of local administration of ketamine (LAK) after third molar surgery. The aim of the present systematic review and meta-analysis was to determine the efficacy of LAK in the control of pain, swelling, and trismus after third molar surgery.

MATERIALS AND METHODS

The study design was a systematic review with a meta-analysis of the effect of LAK after third molar surgery. A search in electronic databases was performed from September 2017 to February 2019. Only prospective clinical trials and randomized controlled trials that had evaluated LAK after third molar surgery were included. The meta-analysis was based on the random effects model. The outcome measures evaluated were postoperative acute pain, swelling, and trismus. The estimated overall effect size was a standardized mean difference (SMD).

RESULTS

A total of 110 study subjects (men and women aged 18 to 50 years) were evaluated for the analgesic effect. The SMD showed a significant analgesic effect (postoperative pain control) favoring LAK (SMD, -1.7403; 95% confidence interval [CI], -2.45 to -1.04). Evaluation of the anti-inflammatory effect of LAK included 105 study subjects and resulted in significantly less swelling in the first postoperative day (SMD, -0.6169; 95% CI, -1.1654 to -0.0683). However, LAK did not reduce the incidence of trismus after third molar surgery (SMD, -0.7241; 95% CI, -2.2765 to 0.8284).

CONCLUSIONS

The use of LAK can reduce the incidence and severity of postoperative pain after third molar surgery and had an anti-inflammatory effect, although only in the first postoperative day. However, LAK had no effect on trismus reduction after third molar surgery.

American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on Perioperative Opioid Minimization in Opioid-Naïve Patients

Surgical care episodes place opioid-naïve patients at risk for transitioning to new persistent postoperative opioid use. With one of the central principles being the application of multimodal pain interventions to reduce the reliance on opioid-based medications, enhanced recovery pathways provide a framework that decreases perioperative opioid use. The fourth Perioperative Quality Initiative brought together a group of international experts representing anesthesiology, surgery, and nursing with the objective of providing consensus recommendations on this important topic. Fourth Perioperative Quality Initiative was a consensus-building conference designed around a modified Delphi process in which the group alternately convened for plenary discussion sessions in between small group discussions. The process included several iterative steps including a literature review of the topics, building consensus around the important questions related to the topic, and sequential steps of content building and refinement until agreement was achieved and a consensus document was produced. During the fourth Perioperative Quality Initiative conference and thereafter as a writing group, reference applicability to the topic was discussed in any area where there was disagreement. For this manuscript, the questions answered included (1) What are the potential strategies for preventing persistent postoperative opioid use? (2) Is opioid-free anesthesia and analgesia feasible and appropriate for routine operations? and (3) Is opioid-free (intraoperative) anesthesia associated with equivalent or superior outcomes compared to an opioid minimization in the perioperative period? We will discuss the relevant literature for each questions, emphasize what we do not know, and prioritize the areas for future research.