A systematic review of intravenous ketamine for postoperative analgesia

Intraoperative Administration of Esketamine is Associated with Reduced Opioid Consumption After Laparoscopic Gynecological Surgery: A Randomized Controlled Trial

Purpose

To explore the postoperative opioid-sparing effect and incidence of adverse events of different dosages of intraoperative esketamine administration in patients undergoing laparoscopic gynecological surgery.

Patients and Methods

Patients undergoing elective gynecological laparoscopic operation was enrolled and randomly allocated to lower-dose esketamine group, higher-dose esketamine group, or control group. Patients in the two intervention groups received esketamine doses of 0.25 mg/Kg and 0.50 mg/Kg before wound incision. Subsequently, maintenance doses of 0.20 mg/Kg/h and 0.40 mg/Kg/h were administered throughout the procedure, respectively. The control group was given an intravenous injection and a maintenance infusion of normal saline. A patient-controlled analgesia (PCA) intravenous pump containing sufentanil was connected to control postoperative pain. Rescue analgesia was provided with injection of tramadol 100 mg.

Results

In total, 120 subjects were included in data analysis. The 24 hours and 48 hours PCA opioid consumption, 24 hours and 48 hours cumulative opioid in both lower-dose and higher-dose esketamine groups were lower than those in the control group. However, postoperative opioid consumption was comparable between the two intervention groups. No differences were found in extubation time, acute postoperative pain intensity, and incidence of adverse effects among the three groups.

Conclusion

Intraoperative esketamine administration at both low and high doses reduces opioid consumption after gynecological laparoscopic surgery, without increasing the risk of adverse events.

Oral ketamine for acute postoperative analgesia (OKAPA) trial: A randomized controlled, single center pilot study

STUDY OBJECTIVE

Although opioids represent the mainstay of treating surgical pain, their use is associated with significant side effects. There is an urgent need to find new pain relievers with safer side effect profiles. One drug that has been receiving increasing attention is ketamine. By using the oral route of administration, ketamine could potentially be used by patients in a less resource-intensive manner with similar efficacy. This study aims to examine the role of oral ketamine in improving recovery after major spine surgery.

DESIGN

A prospective, single-center, double blinded parallel arm, placebo controlled randomized feasibility trial.

SETTING

Toronto Western Hospital (TWH), UHN, Toronto, Canada.

PATIENTS

Adult patients (aged 18-75) undergoing multi-level lumbar spine decompression and fusion with planned overnight admission in hospital.

INTERVENTIONS

Study treatment (oral ketamine 30 mg) or matching placebo for three days (nine doses total) or until hospital discharge.

MEASUREMENTS

The primary outcome was the patient-reported Quality of Recovery-15 score (QoR-15). Secondary outcomes were opioid use, pain intensity, pain interference (PROMIS-pain interference questionnaire), mood (PHQ-9) and, side-effects (Generic Assessment of Side Effects Scale).

MAIN RESULTS

Data from 35 patients were analyzed, of which 18 patients in the ketamine group and 17 patients in the placebo group. There were no significant differences identified in QoR-15 scores at postoperative days 1,3,7, and 30. There were also no significant differences found in pain intensity scale scores at postoperative days 1, 3, 7, and 30, and PROMIS and PHQ-9 scores at postoperative days 7 and 30. Significantly less oral opioids were used in the ketamine group compared to the placebo group on postoperative day 3 and by postoperative day 7. In addition, patients in the ketamine group spent significantly less days on oral opioids and trended to be discharged from hospital earlier.

CONCLUSION

This pilot study demonstrated that low dose oral ketamine can be safely used as an adjunct in postoperative pain treatment to help reduce opioid consumption after major spine surgery.

Rationale and design of a large trial of perioperative ketamine for prevention of chronic post-surgical pain

BACKGROUND

Chronic post-surgical pain (CPSP) is recognised as one of the most common and debilitating complications of major surgery. Progression from acute to chronic pain after surgery involves sensitisation of central nervous system pathways with the N-methyl-D-aspartate (NMDA) receptor having a central role. Ketamine is a potent, non-selective NMDA antagonist commonly used for management of acute postoperative pain. Inconsistent but largely supportive evidence from small trials of a preventative effect of perioperative ketamine on CPSP risk suggests that a confirmative large trial is needed.

METHODS

The ROCKet (Reduction Of Chronic Post-surgical Pain with Ketamine) Trial is a multicentre, double-blind, placebo-controlled, individually randomised superiority trial conducted in 36 hospitals across Australia, New Zealand, and Hong Kong. The trial aims to recruit 4884 patients undergoing abdominal, thoracic, or major orthopaedic surgery. Eligible participants are randomised equally to perioperative intravenous ketamine or placebo for up to 72 h. Incidence of pain in the area of the index surgery is measured by structured telephone interview at 3 months (primary trial endpoint) and 12 months. Pain severity, nature, and associated psychological and quality of life indices are measured using the modified Brief Pain Inventory short form, Neuropathic Pain Questionnaire, Kessler K-10 Psychological Distress Scale, Pain Catastrophising Scale, EQ-5D-3L, and measures of healthcare utilisation and costs. The trial is being conducted by the Department of Critical Care, University of Melbourne, and the Australian and New Zealand College of Anaesthetists Clinical Trials Network. The trial is funded by the Australian National Health and Medical Research Council.

DISCUSSION

The ROCKet trial will clarify the effectiveness of ketamine in primary prevention of CPSP. In addition, it will provide high-quality, prospective data on the epidemiology of CPSP which will better inform further research into prevention and management of CPSP.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12617001619336) on the date of 12/11/2017.

Intraoperative ketamine and pain after video-assisted thoracoscopic surgery (VATS): A systematic review and meta-analysis

BACKGROUND

Video-assisted thoracoscopic surgery (VATS) reduces postoperative discomfort and expedites recovery compared to open thoracotomy. Effective postoperative pain management is crucial to enhance recovery and reduce complications. Ketamine, an NMDA receptor antagonist, has shown promise, though its efficacy in VATS remains uncertain. This meta-analysis aims to evaluate the efficacy and safety of ketamine in reducing acute pain in VATS patients.

METHODS

A comprehensive search of MEDLINE (PubMed), CENTRAL, Embase, Science Direct, Scopus, and clinicaltrials.gov was conducted. Eligible studies were randomized controlled trials (RCTs) comparing intraoperative intravenous ketamine with normal saline in VATS patients and reporting postoperative pain scores. Statistical analyses were performed using R version 4.3.3. Cochrane risk of bias (RoB2) tool was used to assess the quality of included studies.

RESULTS

A total of 10 RCTs with 1151 participants were included. Ketamine was associated with a significant reduction in postoperative pain at 12 (MD -0.65, p = 0.04) and 48 h (MD -0.55 points, p < 0.01) post-surgery. No significant difference was observed in pain scores within the first 3 h, at 6 and 12 h, 24-h postoperative opioid consumption, urine output, surgery duration, rescue analgesia, mean arterial pressure, infusion volume, heart rate, extubation time, and blood loss. The certainty of evidence ranged from moderate to low across the outcomes.

CONCLUSIONS

Intraoperative intravenous ketamine effectively reduces acute postoperative pain in VATS patients but does not significantly impact opioid consumption, hemodynamic parameters, and adverse events. Large-scale studies are needed to confirm these findings and explore ketamine's potential benefits for chronic pain management.

REGISTRATION

PROSPERO (CRD42024527858).

Effect of Low-Dose Esketamine on Postoperative Delirium in Elderly Patients Undergoing Total Hip or Knee Arthroplasty: A Randomized Controlled Trial

Purpose

Postoperative delirium (POD) is a prevalent and severe complication in elderly patients undergoing major surgery, associated with increased morbidity and mortality. This randomized controlled trial aimed to investigate the effects of low-dose esketamine on the incidence of POD in elderly patients underwent total hip or knee arthroplasty.

Patients and Methods

Two hundred and sixty elderly participants were randomly assigned to either the esketamine group (Group E) (0.20mg/kg loading, 0.125mg/kg/h infusion, 0.5 mg/kg for postoperative analgesia) or the placebo group (Group P) (received normal saline). The primary outcome was the incidence of POD, with secondary outcomes including delirium subtypes, duration, intraoperative analgesic consumption, operative and anesthesia times, hemodynamic changes, postoperative pain scores, sleep quality, and common postoperative adverse events.

Results

There was no significant difference in the incidence of POD between Group E (8.5%) and Group P (10.8%). No significant differences were observed for the time of delirium onset, duration of delirium, and delirium subtype between the two groups. Patients in the esketamine group had more stable hemodynamic profile after induction and reduced the pain score of motion on the first two days postoperatively but increased the incidence of postoperative dizziness.

Conclusion

The repeated infusion of low-dose esketamine did not reduce the incidence of POD during the initial three postoperative days in elderly patients following total hip or knee arthroplasty.

Opioids Diminish the Placebo Antidepressant Response: A Post Hoc Analysis of a Randomized Controlled Ketamine Trial

Background

The endogenous opioid system is thought to play a role in the placebo antidepressant response. A recent trial comparing the rapid antidepressant effects of ketamine versus placebo in surgical patients, some of whom were on chronic opioid therapy, revealed a substantial placebo effect. This finding provided an opportunity to test the hypothesis that opioid agonist exposure interacts with placebo antidepressant responses.

Methods

This post hoc analysis utilized data from a previously reported randomized, anesthesia-blinded, placebo-controlled trial of intravenous ketamine in depressed patients undergoing routine surgery. Mixed-effects models were used to determine whether baseline opioid use influenced antidepressant responses to the trial interventions, as measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) over 1 to 14 days post-treatment.

Results

In the placebo arm, baseline opioid use was associated with a 10-point increase (95% CI: 0.81-19.4) in MADRS scores across all post-treatment time points, indicating worse depression in this subgroup. In an alternative model using percent change in MADRS scores, the difference between opioid users and non-users was 38.4% (95% CI: 8.59-68.2), with opioid users experiencing less improvement. For ketamine-treated participants, baseline opioid use did not significantly impact MADRS scores or the percent change in MADRS scores. Pain intensity was not a significant predictor of MADRS outcomes, and the correlation between post-treatment MADRS scores and pain intensity was negligible (R=0.12).

Limitations

This analysis was unregistered and conducted on a small sample; the findings need to be confirmed by prospective controlled studies.

Conclusions

Opioid use at baseline attenuated the placebo antidepressant response independently of pain in depressed patients who received the study treatment under general anesthesia for routine surgery. The antidepressant response was preserved in opioid users who received intravenous ketamine.

Effect of Low-dose Ketamine Infusion on Opioid Consumption in Children Undergoing Open Cardiac Surgery: A Randomized Controlled Double-Blind Study

OBJECTIVE

This study was designed to evaluate the effect of low-dose ketamine infusion on the perioperative consumption of opioids in pediatric open cardiac surgery.

DESIGN

A randomized, controlled, double-blinded single-center study was conducted.

SETTING

The study took place in a tertiary care children's hospital.

PARTICIPANTS

Patients of both sexes aged 2-12 years who underwent cardiac surgery were included.

INTERVENTIONS

Patients in the ketamine group received a bolus of 0.3 mg/kg of ketamine before skin incision followed by continuous intraoperative infusion of 0.25 mg/kg/h and postoperative infusion of 0.1 mg/kg/h for 24 h. Patients in the control groups received volumes of normal saline either bolus or continuous infusion like that of the ketamine group.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the total dose of fentanyl consumed over the first 24 hours postoperatively. Secondary outcomes were intraoperative fentanyl consumption, time to extubation, modified objective pain score, and incidence of vomiting, pruritus, diplopia, or hallucinations. A total of 80 patients were recruited but the final analysis was done on 35 patients in the ketamine group and 34 in the control group. Fentanyl consumption during surgery and in the first 24 hours postoperatively was significantly lower in the ketamine than the control group. Patients in both the ketamine and control groups had similar times to extubation. Modified objective pain scores were significantly lower in the ketamine group than the control group. None of the patients in either group had diplopia or hallucinations.

CONCLUSIONS

Low-dose ketamine infusion in children undergoing open cardiac surgery reduced intra- and postoperative opioid consumption and postoperative pain scores. Moreover, ketamine did not cause diplopia or hallucinations.

Adjuvant Analgesics in Acute Pain - Evaluation of Efficacy

PURPOSE OF THE REVIEW

Acute postoperative pain impacts a significant number of patients and is associated with various complications, such as a higher occurrence of chronic postsurgical pain as well as increased morbidity and mortality.

RECENT FINDINGS

Opioids are often used to manage severe pain, but they come with serious adverse effects, such as sedation, respiratory depression, postoperative nausea and vomiting, and impaired bowel function. Therefore, most enhanced recovery after surgery protocols promote multimodal analgesia, which includes adjuvant analgesics, to provide optimal pain control. In this article, we aim to offer a comprehensive review of the contemporary literature on adjuvant analgesics in the management of acute pain, especially in the perioperative setting. Adjuvant analgesics have proven efficacy in treating postoperative pain and reducing need for opioids. While ketamine is an established option for opioid-dependent patients, magnesium and α2-agonists have, in addition to their analgetic effect, the potential to attenuate hemodynamic responses, which make them especially useful in painful laparoscopic procedures. Furthermore, α2-agonists and dexamethasone can extend the analgesic effect of regional anesthesia techniques. However, findings for lidocaine remain inconclusive.

Association Between Low-Dose Ketamine After Periacetabular and/or Femoral Osteotomy and Postoperative Opioid Requirements

Background

Previous studies have sought to determine the effect of inpatient ketamine therapy on postoperative pain in a variety of surgical specialties.

Purpose

To determine the effects of postoperative ketamine analgesia after periacetabular osteotomy (PAO) and/or derotational femoral osteotomy (DFO) on opioid requirements, pain, and discharge time.

Study Design

Cohort study; Level of evidence, 3.

Methods

Prospective data were collected on 145 patients who underwent PAO and/or DFO by the senior author between January 2021 and December 2022. Hip arthroscopy was performed 3 to 10 days before addressing any intra-articular pathology. In 2021, patients (n = 91 procedures; control group) received a traditional postoperative multimodal pain regimen. In 2022, postoperative low-dose ketamine (0.1-1 mg/kg/h) was added to the multimodal analgesic approach until 24 hours before discharge (n = 81 procedures; ketamine group). The ketamine and control groups were matched based on procedure type. Total opioid consumption was collected using milligram morphine equivalents (MMEs) for both groups. Postoperative pain was measured using the Defense and Veterans Pain Rating Scale (DVPRS), which was analyzed as the mean score per day. Data on the mean MME and DVPRS were analyzed for up to 7 days postoperatively. Linear mixed statistical analysis was performed to determine the significance of low-dose postoperative ketamine on postoperative pain and opioid utilization.

Results

Patients who did not receive ketamine after PAO and/or DFO utilized a mean of 181 ± 335 MMEs and had a mean DVPRS score of 4.18 ± 1.63. Patients who received postoperative ketamine required a mean of 119 ± 291 MMEs and had a mean DVPRS score of 4.34 ± 1.61. The ketamine group was found to consume a significantly lower total MME dose per day (P < .001). No significant difference was found in the mean DVPRS score between the ketamine and control groups (P = .42). Also, no significant difference was found on the day of discharge (P = .79).

Conclusion

Patients who received postoperative ketamine after PAO and/or DFO had a significant decrease in MME dose when compared with a control group of patients who did not receive ketamine. Surgeons should consider adding ketamine to their postoperative multimodal pain control protocol to decrease opioid consumption while adequately addressing postoperative pain.

Ketamine intolerance in patients on enhanced recovery after surgery protocols undergoing colorectal operations

BACKGROUND

Ketamine is used in enhanced recovery after surgery (ERAS) protocols because of its beneficial antihyperalgesic and antitolerance effects. However, adverse effects such as hallucinations, sedation, and diplopia could limit ketamine's utility. The main objective of this study was to identify rates of ketamine side effects in postoperative patients after colorectal surgery and, secondarily, to compare short-term outcomes between patients receiving ketamine analgesia and controls.

METHODS

This was a retrospective observational cohort study. Subjects were adults who underwent ERAS protocol-guided colorectal surgery at a large, integrated health system. Patients were grouped into ketamine-receiving and preketamine cohorts. Patients receiving ketamine were divided into tolerant and intolerant groups. Propensity score-adjusted models tested multivariate associations of ketamine tolerance/intolerance vs control group.

RESULTS

A total of 732 patients underwent colorectal surgery within the ERAS program before ketamine's introduction (control). After ketamine's introduction, 467 patients received the medication. Intolerance was seen in 29% of ketamine recipients, and the most common side effect was diplopia. Demographics and surgical variables did not differ between cohorts. Multivariate models revealed no significant differences in hospital stays. Pain scores in the first 24 hours after surgery were slightly higher in patients receiving ketamine. Opiate consumption after surgery was lower for both ketamine tolerant and ketamine intolerant cohorts than for controls.

CONCLUSION

Rates of ketamine intolerance are high, which can limit its use and potential effectiveness. Ketamine analgesia significantly reduced opiate consumption without increasing hospital stays after colorectal surgery, regardless of whether it was tolerated.

The 2023 WSES guidelines on the management of trauma in elderly and frail patients

BACKGROUND

The trauma mortality rate is higher in the elderly compared with younger patients. Ageing is associated with physiological changes in multiple systems and correlated with frailty. Frailty is a risk factor for mortality in elderly trauma patients. We aim to provide evidence-based guidelines for the management of geriatric trauma patients to improve it and reduce futile procedures.

METHODS

Six working groups of expert acute care and trauma surgeons reviewed extensively the literature according to the topic and the PICO question assigned. Statements and recommendations were assessed according to the GRADE methodology and approved by a consensus of experts in the field at the 10th international congress of the WSES in 2023.

RESULTS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage, including drug history, frailty assessment, nutritional status, and early activation of trauma protocol to improve outcomes. Acute trauma pain in the elderly has to be managed in a multimodal analgesic approach, to avoid side effects of opioid use. Antibiotic prophylaxis is recommended in penetrating (abdominal, thoracic) trauma, in severely burned and in open fractures elderly patients to decrease septic complications. Antibiotics are not recommended in blunt trauma in the absence of signs of sepsis and septic shock. Venous thromboembolism prophylaxis with LMWH or UFH should be administrated as soon as possible in high and moderate-risk elderly trauma patients according to the renal function, weight of the patient and bleeding risk. A palliative care team should be involved as soon as possible to discuss the end of life in a multidisciplinary approach considering the patient's directives, family feelings and representatives' desires, and all decisions should be shared.

CONCLUSIONS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage based on assessing frailty and early activation of trauma protocol to improve outcomes. Geriatric Intensive Care Units are needed to care for elderly and frail trauma patients in a multidisciplinary approach to decrease mortality and improve outcomes.

The Effect of Preprocedural Low-Dose Ketamine for Pain and Anxiety in Patients during Thoracic Epidural Catheterization

Background and Objectives: Thoracic epidural catheterization (TEC) can be both uncomfortable and fearful for patients when performed awake with the thought that the procedure may be painful. The aim of this study was to assess the effect of low-dose intravenous ketamine administration on pain and anxiety during the TEC procedure. Materials and Methods: Sixty patients were randomly divided into two groups to receive intravenous (IV) placebo (Group P) and IV low-dose (0.15 mg/kg) ketamine (LDK) (Group K) 3 min before the procedure in a double-blind manner. A visual analog scale (VAS) was used to measure anxiety (VAS-A) and pain (VAS-P) scores. Vital parameters were monitored before premedication (T1), 20 min after premedication (T2), during skin anesthesia (T3), during TEC (T4), and 5 min after TEC (T5). VAS-A values were recorded at T1, T3, T4, and T5 periods, and VAS-P levels were noted at T3, T4, and T5 periods. Results: During TEC (T4), both VAS-P and VAS-A were significantly lower in Group K (p < 0.001). The mean VAS-A value was 10.6 mm lower, and the mean VAS-P value was 9 mm lower in Group K than in Group P at the T4 time point. Additionally, the mean VAS-P value was 7.7 mm lower in Group K compared to Group P at the T3 time point (p < 0.001). Both groups showed a statistically significant difference in VAS-A measurements when compared at their respective time points (p < 0.001). However, only Group P demonstrated a statistically significant difference in VAS-P measurements (p < 0.001). VAS-P values remained stable in Group K. The number of patients who did not recall the procedure was significantly higher in Group K (p < 0.001). Furthermore, the number of patients who would consent to the same procedure in the future was significantly higher in Group K (p = 0.007). Conclusions: A preprocedural LDK (0.15 mg/kg) can effectively prevent anxiety and pain experienced by patients during the TEC procedure. Administration of LDK may provide a more comfortable procedure process without causing ketamine-induced side effects (hemodynamic, respiratory, and psychological).

Dexmedetomidine - An Alternative to Midazolam in the Treatment of Ketamine-Induced Emergence Delirium: A Systematic Review

PURPOSE

Analyze the effectiveness of dexmedetomidine compared to midazolam for the treatment of ketamine-induced emergence delirium in noncardiac surgical patients.

DESIGN

Systematic review.

METHODS

Guidelines outlined in the Preferred Reporting Items For Systematic Reviews and Meta-analyses (PRISMA)22 were used for this review. PubMed, Cumulative Index To Nursing And Allied Health Literature (CINAHL), MEDLINE, The Cochrane Library, EBSCOhost, National Institute of Health clinical trials, Google Scholar, and gray literature were searched for relevant studies. Only peer-reviewed nonexperimental studies, quasi-experimental studies, and randomized control trials with or without meta-analysis were included. The evidence was assessed using the Johns Hopkins Nursing Evidence-Based Practice guidelines for quality ratings and evidence level.

FINDINGS

Five blinded randomized controlled trials, three quasi-experimental studies, and two retrospective nonexperimental studies comprised of 1,024 subjects were evaluated for this review. Dexmedetomidine was more effective at reducing ketamine-induced delirium in adult patients, although midazolam attenuated the psychomimetic effects of ketamine better in pediatric patients. Furthermore, postanesthesia care unit discharge times were similar between patients treated with dexmedetomidine and midazolam. The studies in this review were categorized as Level I, Level II, or Level III and rated Grade A, implying strong confidence in the actual effects of dexmedetomidine in all outcome measures of the review.

CONCLUSIONS

The current evidence suggests that dexmedetomidine is an effective alternative for alleviating ketamine-induced delirium in noncardiac adult surgical patients. Multiple studies in this review noted improved hemodynamics and reduced postoperative analgesic requirements after administration of dexmedetomidine in conjunction with ketamine.

Intravenous Ketamine Exacerbating Symptoms of Acute Stress Disorder: A Case Report and Systematized Review of Existing Literature

BACKGROUND

Ketamine is an anesthetic and analgesic known for its psychotomimetic properties, such as dissociation and altered perception. Acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) are characterized by unwanted memories, intrusive thoughts, and dissociative flashbacks following an acute traumatic event. It is unknown how analgesic ketamine affects the symptomatology of ASD when administered to patients in the posttraumatic period.

OBJECTIVE AND METHODS

In this article, we present the case of a 26-year-old man who sustained gunshot wounds and developed worsened ASD after receiving analgesic ketamine. We also present a review of the current literature on peritraumatic ketamine and its subsequent effect on ASD and PTSD.

RESULTS

In 2 out of 3 articles examining ketamine and ASD, ketamine was associated with worsened symptomatology of ASD. There were 6 articles examining ketamine and PTSD. In 1 of 6 articles, ketamine was associated with increased incidence and/or severity of PTSD, and in 2 of 6, it was associated with decreased incidence and/or severity of PTSD. There was no relationship between ketamine and subsequent PTSD in 3 of 6 articles.

CONCLUSION

We conclude that ketamine's psychotomimetic properties may exacerbate the dissociative and perceptual symptoms of ASD, but its long-term effects on PTSD are still unclear. In patients with preexisting ASD, the potential risks and benefits of using analgesic ketamine must be weighed carefully.

Effects of S-ketamine added to patient-controlled analgesia on early postoperative pain and recovery in patients undergoing thoracoscopic lung surgery: A randomized double-blinded controlled trial

STUDY OBJECTIVE

To investigate whether the addition of S-ketamine to patient-controlled hydromorphone analgesia decreases postoperative moderate-to-severe pain and improves the quality of recovery (QoR) in patients undergoing thoracoscopic lung surgery.

DESIGN

Single-center prospective randomized double-blinded controlled trial.

SETTING

Tertiary university hospital.

PATIENTS

242 patients undergoing thoracoscopic lung surgery.

INTERVENTIONS

Patients were randomized to receive intravenous patient-controlled analgesia (IV-PCA) with hydromorphone alone or hydromorphone combined with S-ketamine (0.5 mg/kg/48 h, 1 mg/kg/48 h, or 2 mg/kg/48 h).

MEASUREMENTS

Primary outcome was proportion of patients with moderate-to-severe pain. (numerical rating scale [NRS] pain scores ≥4 when coughing) within 2 days after surgery. Postoperative QoR scores and other prespecified outcomes were also recorded.

MAIN RESULTS

Of 242 enrolled patients, 220 were included in the final analysis. The results demonstrated that the incidence of postoperative moderate-to-severe pain was significantly different between the hydromorphone group and combined S-ketamine group (absolute difference, 27.9%; 95% confidence interval [CI], 11.7% to 42.1%; P < 0.001). Patients who received S-ketamine had lower NRS pain scores at rest and when coughing on postoperative day 1 (POD1; median difference 1 and 1, P < 0.001) and postoperative day 2 (POD2; median difference 1 and 1, P < 0.001). The QoR-15 scores were higher in the combined S-ketamine group on POD1 (mean difference 6, P < 0.001) and POD2 (mean difference 6, P < 0.001) than in the hydromorphone group. A higher dose of S-ketamine was associated with deeper sedation. No differences were detected in the other safety outcomes.

CONCLUSIONS

Addition of S-ketamine to IV-PCA hydromorphone significantly reduced the incidence of postoperative moderate-to-severe pain and improved the QoR in patients undergoing thoracoscopic lung surgery.

TRIAL REGISTRATION

Chinese Clinical Trail Register (identifier: ChiCTR2200058890).

The Role of Ketamine as a Component of Multimodal Analgesia in Burns: A Retrospective Observational Study

Background: Burn wound dressing and debridement are excruciatingly painful procedures that call for appropriate analgesia-typically multimodal. Better post-procedural pain management, less opioid use, and consequently fewer side effects, which could prolong recovery and increase morbidity, are all benefits of this type of analgesia. Intravenously administered ketamine can be effective as monotherapy or in combination with opioids, especially with procedural sedation such as in burn wound dressing. Methods: This observational study investigated the effect of ketamine administered in subanesthetic doses combined with opioids during burn wound dressing. The study was conducted from October 2018 to October 2021. A total of 165 patients met the inclusion criteria. A total of 82 patients were in the ketamine group, while 83 patients were dressed without ketamine. The main outcome was the effect of ketamine on intraprocedural opioid consumption. The secondary outcome included the effect of ketamine on postprocedural pain control. Results: Patients dressed with ketamine were significantly older (p = 0.001), while the mean doses of intraoperatively administered propofol and fentanyl were significantly lower than in patients dressed without ketamine (150 vs. 220 mg, p < 0.001; and 0.075 vs. 0.150 mg, p < 0.001; respectively). Conclusions: Ketamine was an independent predictor of lower intraoperative fentanyl consumption, according to the multivariate regression analysis (p = 0.015). Contrarily, both groups of patients required postoperative tramadol treatment, while intraoperative ketamine administration had no beneficial effects on postoperative pain management.

Optimizing the use of ketamine to reduce chronic postsurgical pain in women undergoing mastectomy for oncologic indication: study protocol for the KALPAS multicenter randomized controlled trial

BACKGROUND

Mastectomies are commonly performed and strongly associated with chronic postsurgical pain (CPSP), more specifically termed postmastectomy pain syndrome (PMPS), with 25-60% of patients reporting pain 3 months after surgery. PMPS interferes with function, recovery, and compliance with adjuvant therapy. Importantly, it is associated with chronic opioid use, as a recent study showed that 1 in 10 patients continue to use opioids at least 3 months after curative surgery. The majority of PMPS patients are women, and, over the past 10 years, women have outpaced men in the rate of growth in opioid dependence. Standard perioperative multimodal analgesia is only modestly effective in prevention of CPSP. Thus, interventions to reduce CPSP and PMPS are urgently needed. Ketamine is well known to improve pain and reduce opioid use in the acute postoperative period. Additionally, ketamine has been shown to control mood in studies of anxiety and depression. By targeting acute pain and improving mood in the perioperative period, ketamine may be able to prevent the development of CPSP.

METHODS

Ketamine analgesia for long-lasting pain relief after surgery (KALPAS) is a phase 3, multicenter, randomized, placebo-controlled, double-blind trial to study the effectiveness of ketamine in reducing PMPS. The study compares continuous perioperative ketamine infusion vs single-dose ketamine in the postanesthesia care unit vs placebo for reducing PMPS. Participants are followed for 1 year after surgery. The primary outcome is pain at the surgical site at 3 months after the index surgery as assessed with the Brief Pain Inventory-short form pain severity subscale.

DISCUSSION

This project is part of the NIH Helping to End Addiction Long-term (HEAL) Initiative, a nationwide effort to address the opioid public health crisis. This study can substantially impact perioperative pain management and can contribute significantly to combatting the opioid epidemic.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05037123. Registered on September 8, 2021.

Ketofol versus Dexmedetomidine for preventing postoperative delirium in elderly patients undergoing intestinal obstruction surgeries: a randomized controlled study

PURPOSE

Postoperative delirium (POD) is considered the most common postoperative neurological complication in elderly patients. The aim of this study was to evaluate the efficacy of the administration of ketofol versus dexmedetomidine (DEX) for minimizing POD in elderly patients undergoing urgent exploration for intestinal obstruction.

METHODS

This prospective double-blinded randomized clinical trial was conducted on 120 elderly patients undergoing urgent exploration for intestinal obstruction. Patients were randomly allocated to one of the three groups: Group C (control group) patients received normal saline 0.9%, group D received dexmedetomidine, and group K received ketofol (ketamine: propofol was 1:4). The primary outcome was the incidence of POD. Secondary outcomes were incidence of emergence agitation, postoperative pain, consumption of rescue opioids, hemodynamics, and any side effects.

RESULTS

The incidence of POD was statistically significantly lower in ketofol and DEX groups than in the control group at all postoperative time recordings. Additionally, VAS scores were statistically significantly decreased in the ketofol and DEX groups compared to the control group at all time recordings except at 48 and 72 h postoperatively, where the values of the three studied groups were comparable. The occurrence of emergence agitation and high-dose opioid consumption postoperatively were found to be significant predictors for the occurrence of POD at 2 h and on the evening of the 1st postoperative day.

CONCLUSION

The administration of ketofol provides a promising alternative option that is as effective as DEX in reducing the incidence of POD in elderly patients undergoing urgent exploration for intestinal obstruction.

TRIAL REGISTRATION

This clinical trial was approved by the Institutional Review Board (IRB) at Zagazig University (ZU-IRB# 6704// 3/03/2021) and ClinicalTrials.gov (NCT04816162, registration date 22/03/ 2021). The first research participant was enrolled on 25/03/2021).

Association between intraoperative ketamine and the incidence of emergence delirium in laparoscopic surgeries: an observational study

BACKGROUND

Emergence Delirium (ED) is an essential condition in the immediate postoperative period. Systematic review and meta-analysis of randomized controlled trials have concluded that the effect of ketamine on postoperative delirium remains unclear. The present study sought to evaluate if the intraoperative use of ketamine for postoperative analgesia is associated with postoperative ED in laparoscopic surgeries.

METHODS

A prospective observational study was performed in the PostAnesthetic Care Unit (PACU) to evaluate patients who had undergone laparoscopic surgery under a rigid intraoperative anesthesia protocol from July 2018 to January 2019. Patients submitted to laparoscopic surgery for cholecystectomy, oophorectomy, or salpingectomy with a score ≥1 on the Richmond Assessment Sedation Scale (RASS) or ≥2 on the Nursing Delirium Screening Scale (Nu-DESC) were considered to have ED. t-test, Chi-Square test or Fisher's exact tests were used for comparison.

RESULTS

One hundred and fifteen patients were studied after laparoscopic surgery. Seventeen patients (14.8%) developed ED, and the incidence of ED in patients who received ketamine was not different from that of other patients (18.3% vs. 10.6%, p = 0.262). Patients with ED had more postoperative pain and morphine requirement at the PACU (p = 0.005 and p = 0.025, respectively). Type of surgery (general surgery, OR = 6.4, 95% CI 1.2‒35.2) and postoperative pain (OR = 3.7, 95% CI 1.2‒11.4) were risk factors for ED.

CONCLUSION

In this study, no association was found between ED and intraoperative administration of ketamine in laparoscopic surgeries. Type of surgery and postoperative pain were risk factors for ED.

The role of neurotrophic factors in novel, rapid psychiatric treatments

Neurotrophic factors are a family of growth factors that modulate cellular growth, survival, and differentiation. For many decades, it has been generally believed that a lack of neurotrophic support led to the decreased neuronal synaptic plasticity, death, and loss of non-neuronal supportive cells seen in neuropsychiatric disorders. Traditional psychiatric medications that lead to immediate increases in neurotransmitter levels at the synapse have been shown also to elevate synaptic neurotrophic levels over weeks, correlating with the time course of the therapeutic effects of these drugs. Recent advances in psychiatric treatments, such as ketamine and psychedelics, have shown a much faster onset of therapeutic effects (within minutes to hours). They have also been shown to lead to a rapid release of neurotrophins into the synapse. This has spurred a significant shift in understanding the role of neurotrophins and how the receptor tyrosine kinases that bind neurotrophins may work in concert with other signaling systems. In this review, this renewed understanding of synaptic receptor signaling interactions and the clinical implications of this mechanistic insight will be discussed within the larger context of the well-established roles of neurotrophic factors in psychiatric disorders and treatments.

Effect of Local Ketamine Subcutaneous Injection at the Incision Site in Reducing the Postoperative Pain Score after Transabdominal Hysterectomy

Background

Pain control after operations is essential in decreasing the patient recovery period and potential morbidity. Prescribing opiates is very effective, but significant side effects accompany them. This study aims to examine the effect of local ketamine infiltration in decreasing pain intensity in patients undergoing transabdominal hysterectomy.

Methods

In this double-blind, randomized, controlled clinical trial, a total of 92 patients undergoing transabdominal hysterectomy aged 30-60 years were selected and divided into two intervention and control groups randomly. For the intervention group, ketamine was injected subcutaneously into the incision site at a dose of 0.5 mg/kg after the operation. In the control group, 5 mg normal saline was used in the same method. Postoperative pain intensity was measured using the visual analog scale (VAS: 0-10). The pain score and dose of administered opioids were documented at 1, 2, 4, 6, 12, and 24 hours and compared between the two groups.

Results

Postoperative pain intensity was significantly lower in the intervention group than in the control group, except for hour 24. The mean amounts of administered opioids were significantly lower in the intervention group at hours 6 and 12, as well as the total amount of used opioids, and no significant side effects were documented.

Conclusion

Local ketamine subcutaneous injection in the incisional site is effective and is a safe procedure for reducing pain scores in patients who underwent a transabdominal hysterectomy.

Ketamine for Traumatic Assault-Induced Depression: A Case Report

BACKGROUND

This case report describes the use of ketamine as a rapid, effective treatment of depression in a 68-year-old female patient with no significant medical history of psychiatric disorders. Patients who experience intentional or unintentional traumas are at an increased risk for developing depression or posttraumatic stress disorder, and emerging evidence has supported the use of ketamine as an alternative treatment of depression.

CASE PRESENTATION

This is the case of a 68-year-old female patient who was assaulted, resulting in multiple stab wounds to both hands and the right upper quadrant. She underwent placement of a chest tube and surgical repair of the liver and was subsequently admitted to the intensive care unit. These events led to the development of severe depression symptoms, as evidenced by a Montgomery-Asberg Depression Rating Scale (MADRS) score of 37. As treatment of her acute depression, the patient received a single intravenous dose of ketamine (0.5 mg/kg) infused over 40 min and was monitored for side effects. The MADRS is a 10-item depression screening tool that assesses symptoms and changes over time. Within 4 hr of receiving ketamine, the patient reported a significant improvement in her mood and her MADRS score decreased to 16, classifying this patient as experiencing mild depression. The patient continued to improve, and 24 hr after receiving ketamine, her MADRS score was 4, indicating remission of her depression symptoms.

CONCLUSION

This case report aims to provide an account of the potential benefits of ketamine as a rapid treatment of depression in an adult trauma patient.

Pain in Colorectal Surgery: How Does It Occur and What Tools Do We Have for Treatment?

Pain is a complex entity with deleterious effects on the entire organism. Poorly controlled postoperative pain impacts the patient outcome, being associated with increased morbidity, inadequate quality of life and functional recovery. In the current surgical environment with less invasive surgical procedures increasingly being used and a trend towards rapid discharge home after surgery, we need to continuously re-evaluate analgesic strategies. We have performed a narrative review consisting of a description of the acute surgical pain anatomic pathways and the connection between pain and the surgical stress response followed by reviewing methods of multimodal analgesia in colorectal surgery found in recent literature data. We have described various regional analgesia techniques and drugs effective in pain treatment, emphasizing their advantages and concerns. We have also tried to identify present knowledge gaps requiring future research. Our review concludes that surgical pain has peculiarities that make its management complex, implying a consistent, multimodal approach aiming to block both peripheral and central pain pathways.

Global Trends in Research of Perioperative Analgesia Over Past 10 Years: A Bibliometric Analysis

Background

The postoperative acute pain caused by surgery has been a major problem plaguing anesthesiologists, and even some acute pain progresses to chronic pain syndrome, terribly reducing the quality of life of patients. To this end, increasing attention has been paid to the management of perioperative analgesia. At present, with the increase of research on perioperative analgesia, the understanding and solution of this clinical problem have been further developed. Bibliometrics can estimate research hot-spots and trends of related fields in a certain period of time. However, a systematic bibliometric analysis has not been conducted to explore current research hotspots and future development trends, which is thus the purpose of this study.

Methods

Articles and reviews published from 2012 to 2021 were retrieved from the Web of Science Core Collection (WoSCC) database, and the bibliometric analysis of the keywords and references of articles was performed using VOSviewer1.6.18. Besides, the number of articles related to perioperative analgesia in term of countries, affiliations, authors, and journals were analyzed.

Results

Finally, 3157 articles meeting the screening requirements were retrieved, and it was hereby found that the research on perioperative analgesia had received more attention and interest in the past 10 years, with the United States making more contributions, where there were eight of the top ten affiliations by the number of publications. Kaye AD was the most active researcher in this field. Most related articles were published in Anesthesia and Analgesia, accounting for 2.76% of all literature. Enhanced recovery after surgery, different types of anesthesia and multi-mode analgesic drug intervention were the main trends and hotspots.

Conclusion

Perioperative analgesia has attracted considerable academic interest. In the past decade, the effects of enhanced recovery after surgery, different types of anesthesia and multi-mode analgesic drug intervention on perioperative analgesia have become the research hotspots, which are also likely to be the focus of future study.

Effect of opioid-free anesthesia on the incidence of postoperative nausea and vomiting: A meta-analysis of randomized controlled studies

BACKGROUND

Research on opioid-free anesthesia has increased in recent years; however, it has never been determined whether it is more beneficial than opioid anesthesia. This meta-analysis was primarily used to assess the effect of opioid-free anesthesia compared with opioid anesthesia on the incidence of postoperative nausea and vomiting.

METHODS

We searched the electronic databases of PubMed, the Cochrane Library, Web of Science and Embase from 2014 to 2022 to identify relevant articles and extract relevant data. The incidence of postoperative nausea and vomiting, time to extubation, pain score at 24 hours postoperatively, and time to first postoperative rescue analgesia were compared between patients receiving opioid-free anesthesia and those receiving standard opioid anesthesia. Differences in the incidence of postoperative nausea and vomiting were evaluated using risk ratios (95% confidence interval [CI]). The significance of the differences was assessed using mean differences and 95% CI. The heterogeneity of the subject trials was evaluated using the I2 test. Statistical analysis was performed using the RevMan 5.4 software.

RESULTS

Fourteen randomized controlled trials, including 1354 participants, were evaluated in the meta-analysis. As seen in the forest plot, the OFA group had a lower risk of postoperative nausea and vomiting than the control group (risk ratios = 0.41, 95% CI: 0.33-0.51, P < .00001; n = 1354), and the meta-analysis also found that the OFA group had lower postoperative analgesia scores at 24 hours (P < .000001), but time to extubation (P = .14) and first postoperative resuscitation analgesia time (P < .54) were not significantly different.

CONCLUSIONS

Opioid-free anesthesia reduces the incidence of postoperative nausea and vomiting while providing adequate analgesia without interfering with postoperative awakening.

Simultaneous quantitation of ketamine, norketamine and dehydronorketamine in human milk using a novel ultra high-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) assay

There is a paucity of data on the transfer of ketamine from maternal blood into human milk. Quantification of ketamine in human milk provides information about the potential exposure of the infant to ketamine and its metabolites from the mother during lactation. A highly specific, reproducible, and sensitive UPLC-MS/MS based analytical method was developed and validated for the quantitation of ketamine and its metabolites (norketamine and dehydronorketamine) in human milk. Samples were subjected to a simple protein precipitation and ketamine-d4 and norketamine-d4 were used as internal standards. Separation of the analytes was achieved using an Acquity UPLC equipped with BEH RP18 1.7 µm, 2.1 × 100 mm column. Mass spectrometric analysis of the analyte ions was carried out using electrospray with positive ionization and multiple reaction monitoring mode. The assay was linear over a concentration range of 1-100 ng/mL for ketamine and norketamine, and 0.1-10 ng/mL for dehydronorketamine. Acceptable intra-day and inter-day accuracy and precision were observed for all the analytes. High recovery of the analytes and minimal matrix effect were observed. Stability of analytes was confirmed at the tested conditions. This assay was successfully used to measure analytes in human milk samples collected from lactating women enrolled in a clinical research study. This is the first validated method that simultaneously quantified ketamine and its metabolites in human milk.

Perioperative Use of Ketamine

PURPOSE OF REVIEW

Postoperative pain continues to be one of the most common challenges following surgeries. Multimodal analgesia has been of particular focus as non-opioid alternatives have been encouraged due to concerns of the opioid epidemic. Ketamine has been an especially useful adjunct in multimodal pain regimens within the past few decades. This article highlights the current use and advances surrounding the perioperative use of ketamine.

RECENT FINDINGS

Ketamine has antidepressive effects at subanesthetic doses. Intraoperative ketamine may be beneficial in reducing postoperative depression. Additionally, newer studies are exploring whether ketamine can be useful in reducing postoperative sleep disturbances. Ketamine continues to be a great tool in perioperative pain control, especially during an opioid epidemic. As its use continues to expand and gain more popularity in the perioperative period, more research could shed light on the additional nonanalgesic benefits of ketamine use.

Enhanced recovery protocols for ambulatory surgery

INTRODUCTION

In the United States, ambulatory surgeries account for up to 87% of all surgical procedures. (1) It was estimated that 19.2 million ambulatory surgeries were performed in 2018 (https://www.hcup-us.ahrq.gov/reports/statbriefs/sb287-Ambulatory-Surgery-Overview-2019.pdf). Cataract procedures and musculoskeletal surgeries are the most common surgical interventions performed in ambulatory centers. However, more complex surgical interventions, such as sleeve gastrectomies, oncological, and spine surgeries, and even arthroplasties are routinely performed as day cases or in a model of an ambulatory extended recovery. (2-5) The ambulatory surgery centers industry has grown since 2017 by 1.1% per year and reached a market size of $31.2 billion. According to the Ambulatory Surgery Center Association, there is a potential to save $57.6 billion in Medicare costs over the next decade (https://www.ibisworld.com/industry-statistics/market-size/ambulatory-surgery-centers-united-states/). These data suggest an expected rise in the volume of ambulatory (same day) or extended ambulatory (23 h) surgeries in coming years. Similar increases are also observed in other countries. For example, 75% of elective surgeries are performed as same-day surgery in the United Kingdom. (6) To reduce costs and improve the quality of care after those more complex procedures, ambulatory surgery centers have started implementing patient-centered, high-quality, value-based practices. To achieve those goals, Enhanced Recovery After Surgery (ERAS) protocols have been implemented to reduce the length of stay, decrease costs, increase patients' satisfaction, and transform clinical practices. The ERAS fundamentals for ambulatory surgery are based on five pillars, including (1) preoperative patient counseling, education, and optimization; (2) multimodal and opioid-sparing analgesia; (3) nausea and vomiting, wound infection, and venous thromboembolism prophylaxis; (4) maintenance of euvolemia; and (5) encouragement of early mobility. Those pillars rely on interdisciplinary teamwork led by anesthesiologists, surgery-specific workgroups, and safety culture. (2) Research shows that a team of ambulatory anesthesiologists is crucial in improving postoperative nausea and vomiting (PONV) and pain control. (7) This review will summarize the current evidence on the elements and clinical importance of implementing ERAS protocol for ambulatory surgery.

The IMpact of PerioperAtive KeTamine on Enhanced Recovery after Abdominal Surgery (IMPAKT ERAS): protocol for a pragmatic, randomized, double-blinded, placebo-controlled trial

BACKGROUND

Multimodal analgesic strategies that reduce perioperative opioid consumption are well-supported in Enhanced Recovery After Surgery (ERAS) literature. However, the optimal analgesic regimen has not been established, as the contributions of each individual agent to the overall analgesic efficacy with opioid reduction remains unknown. Perioperative ketamine infusions can decrease opioid consumption and opioid-related side effects. However, as opioid requirements are drastically minimized within ERAS models, the differential effects of ketamine within an ERAS pathway remain unknown. We aim to pragmatically investigate through a learning healthcare system infrastructure how the addition of a perioperative ketamine infusion to mature ERAS pathways affects functional recovery.

METHODS

The IMPAKT ERAS trial (IMpact of PerioperAtive KeTamine on Enhanced Recovery after Abdominal Surgery) is a single center, pragmatic, randomized, blinded, placebo-controlled trial. 1544 patients undergoing major abdominal surgery will be randomly allocated to receive intraoperative and postoperative (up to 48 h) ketamine versus placebo infusions as part of a perioperative multimodal analgesic regimen. The primary outcome is length of stay, defined as surgical start time until hospital discharge. Secondary outcomes will include a variety of in-hospital clinical end points derived from the electronic health record.

DISCUSSION

We aimed to launch a large-scale, pragmatic trial that would easily integrate into routine clinical workflow. Implementation of a modified consent process was critical to preserving our pragmatic design, permitting an efficient, low-cost model without reliance on external study personnel. Therefore, we partnered with leaders of our Investigational Review Board to develop a novel, modified consent process and shortened written consent form that would meet all standard elements of informed consent, yet also allow clinical providers the ability to recruit and enroll patients during their clinical workflow. Our trial design has created a platform for subsequent pragmatic studies at our institution.

TRIAL REGISTRATION

NCT04625283, Pre-results.

The clinical toxicology of ketamine

INTRODUCTION

Ketamine is a pharmaceutical drug possessing both analgesic and anaesthetic properties. As an anaesthetic, it induces anaesthesia by producing analgesia with a state of altered consciousness while maintaining airway tone, respiratory drive, and hemodynamic stability. At lower doses, it has psychoactive properties and has gained popularity as a recreational drug.

OBJECTIVES

To review the epidemiology, mechanisms of toxicity, pharmacokinetics, clinical features, diagnosis and management of ketamine toxicity.

METHODS

Both OVID MEDLINE (January 1950-April 2023) and Web of Science (1900-April 2023) databases were searched using the term "ketamine" in combination with the keywords "pharmacokinetics", "kinetics", "poisoning", "poison", "toxicity", "ingestion", "adverse effects", "overdose", and "intoxication". Furthermore, bibliographies of identified articles were screened for additional relevant studies. These searches produced 5,268 non-duplicate citations; 185 articles (case reports, case series, pharmacokinetic studies, animal studies pertinent to pharmacology, and reviews) were considered relevant. Those excluded were other animal investigations, therapeutic human clinical investigations, commentaries, editorials, cases with no clinical relevance and post-mortem investigations.

EPIDEMIOLOGY

Following its introduction into medical practice in the early 1970s, ketamine has become a popular recreational drug. Its use has become associated with the dance culture, electronic and dubstep dance events.

MECHANISM OF ACTION

Ketamine acts primarily as a non-competitive antagonist on the glutamate N-methyl-D-aspartate receptor, causing the loss of responsiveness that is associated with clinical ketamine dissociative anaesthesia.

PHARMACOKINETICS

Absorption of ketamine is rapid though the rate of uptake and bioavailability is determined by the route of exposure. Ketamine is metabolized extensively in the liver. Initially, both isomers are metabolized to their major active metabolite, norketamine, by CYP2B6, CYP3A4 and CYP2C9 isoforms. The hydroxylation of the cyclohexan-1-one ring of norketamine to the three positional isomers of hydroxynorketamine occurs by CYP2B6 and CYP2A6. The dehydronorketamine metabolite occurs either by direct dehydrogenation from norketamine via CYP2B6 metabolism or non-enzymatic dehydration of hydroxynorketamine. Norketamine, the dehydronorketamine isomers, and hydroxynorketamine have pharmacological activity. The elimination of ketamine is primarily by the kidneys, though unchanged ketamine accounts for only a small percentage in the urine. The half-life of ketamine in humans is between 1.5 and 5 h.

CLINICAL FEATURES

Acute adverse effects following recreational use are diverse and can include impaired consciousness, dizziness, irrational behaviour, hallucinations, abdominal pain and vomiting. Chronic use can result in impaired verbal information processing, cystitis and cholangiopathy.

DIAGNOSIS

The diagnosis of acute ketamine intoxication is typically made on the basis of the patient's history, clinical features, such as vomiting, sialorrhea, or laryngospasm, along with neuropsychiatric features. Chronic effects of ketamine toxicity can result in cholangiopathy and cystitis, which can be confirmed by endoscopic retrograde cholangiopancreatography and cystoscopy, respectively.

MANAGEMENT

Treatment of acute clinical toxicity is predominantly supportive with empiric management of specific adverse effects. Benzodiazepines are recommended as initial treatment to reduce agitation, excess neuromuscular activity and blood pressure. Management of cystitis is multidisciplinary and multi-tiered, following a stepwise approach of pharmacotherapy and surgery. Management of cholangiopathy may require pain management and, where necessary, biliary stenting to alleviate obstructions. Chronic effects of ketamine toxicity are typically reversible, with management focusing on abstinence.

CONCLUSIONS

Ketamine is a dissociative drug employed predominantly in emergency medicine; it has also become popular as a recreational drug. Its recreational use can result in acute neuropsychiatric effects, whereas chronic use can result in cystitis and cholangiopathy.

Narrative Review: Low-Dose Ketamine for Pain Management

Pain is the leading cause of medical consultations and occurs in 50-70% of emergency department visits. To date, several drugs have been used to manage pain. The clinical use of ketamine began in the 1960s and it immediately emerged as a manageable and safe drug for sedation and anesthesia. The analgesic properties of this drug were first reported shortly after its use; however, its psychomimetic effects have limited its use in emergency departments. Owing to the misuse and abuse of opioids in some countries worldwide, ketamine has become a versatile tool for sedation and analgesia. In this narrative review, ketamine's role as an analgesic is discussed, with both known and new applications in various contexts (acute, chronic, and neuropathic pain), along with its strengths and weaknesses, especially in terms of psychomimetic, cardiovascular, and hepatic effects. Moreover, new scientific evidence has been reviewed on the use of additional drugs with ketamine, such as magnesium infusion for improving analgesia and clonidine for treating psychomimetic symptoms. Finally, this narrative review was refined by the experience of the Pain Group of the Italian Society of Emergency Medicine (SIMEU) in treating acute and chronic pain with acute manifestations in Italian Emergency Departments.

Basic metabolic and vascular effects of ketamine and its interaction with fentanyl

Ketamine is a short-acting general anesthetic with hallucinogenic, analgesic, and amnestic properties. In addition to its anesthetic use, ketamine is commonly abused in rave settings. While safe when used by medical professionals, uncontrolled recreational use of ketamine is dangerous, especially when mixed with other sedative drugs, including alcohol, benzodiazepines, and opioid drugs. Since synergistic antinociceptive interactions between opioids and ketamine were demonstrated in both preclinical and clinical studies, such an interaction could exist for the hypoxic effects of opioid drugs. Here, we focused on the basic physiological effects of ketamine as a recreational drug and its possible interactions with fentanyl-a highly potent opioid that induces strong respiratory depression and robust brain hypoxia. By using multi-site thermorecording in freely-moving rats, we showed that intravenous ketamine at a range of human relevant doses (3, 9, 27 mg/kg) dose-dependently increases locomotor activity and brain temperature, as assessed in the nucleus accumbens (NAc). By determining temperature differentials between the brain, temporal muscle, and skin, we showed that the brain hyperthermic effect of ketamine results from increased intracerebral heat production, an index of metabolic neural activation, and decreased heat loss due to peripheral vasoconstriction. By using oxygen sensors coupled with high-speed amperometry we showed that ketamine at the same doses increases NAc oxygen levels. Finally, co-administration of ketamine with intravenous fentanyl results in modest enhancement of fentanyl-induced brain hypoxia also enhancing the post-hypoxic oxygen increase. Therefore, in contrast to fentanyl, ketamine increases brain oxygenation but potentiates brain hypoxia induced by fentanyl.

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.

The IMpact of PerioperAtive KeTamine on Enhanced Recovery after Abdominal Surgery (IMPAKT ERAS): protocol for a pragmatic, randomized, double-blinded, placebo-controlled trial

BACKGROUND

Multimodal analgesic strategies that reduce perioperative opioid consumption are well-supported in Enhanced Recovery After Surgery (ERAS) literature. However, the optimal analgesic regimen has not been established, as the contributions of each individual agent to the overall analgesic efficacy with opioid reduction remains unknown. Perioperative ketamine infusions can decrease opioid consumption and opioid-related side effects. However, as opioid requirements are drastically minimized within ERAS models, the differential effects of ketamine within an ERAS pathway remain unknown. We aim to pragmatically investigate through a learning healthcare system infrastructure how the addition of a perioperative ketamine infusion to mature ERAS pathways affects functional recovery.

METHODS

The IMPAKT ERAS trial (IMpact of PerioperAtive KeTamine on Enhanced Recovery after Abdominal Surgery) is a single center, pragmatic, randomized, blinded, placebo-controlled trial. 1544 patients undergoing major abdominal surgery will be randomly allocated to receive intraoperative and postoperative (up to 48 hours) ketamine versus placebo infusions as part of a perioperative multimodal analgesic regimen. The primary outcome is length of stay, defined as surgical start time until hospital discharge. Secondary outcomes will include a variety of in-hospital clinical end points derived from the electronic health record.

DISCUSSION

We aimed to launch a large-scale, pragmatic trial that would easily integrate into routine clinical workflow. Implementation of a modified consent process was critical to preserving our pragmatic design, permitting an efficient, low-cost model without reliance on external study personnel. Therefore, we partnered with leaders of our Investigational Review Board to develop a novel, modified consent process and shortened written consent form that would meet all standard elements of informed consent, yet also allow clinical providers the ability to recruit and enroll patients during their clinical workflow. Our trial design has created a platform for subsequent pragmatic studies at our institution.

TRIAL REGISTRATION NUMBER

NCT04625283, Pre-results Protocol Version 1.0, 2021.

The psychotomimetic ketamine disrupts the transfer of late sensory information in the corticothalamic network

In prodromal and early schizophrenia, disorders of attention and perception are associated with structural and chemical brain abnormalities and with dysfunctional corticothalamic networks exhibiting disturbed brain rhythms. The underlying mechanisms are elusive. The non-competitive NMDA receptor antagonist ketamine simulates the symptoms of prodromal and early schizophrenia, including disturbances in ongoing and task & sensory-related broadband beta-/gamma-frequency (17-29 Hz/30-80 Hz) oscillations in corticothalamic networks. In normal healthy subjects and rodents, complex integration processes, like sensory perception, induce transient, large-scale synchronised beta/gamma oscillations in a time window of a few hundred ms (200-700 ms) after the presentation of the object of attention (e.g., sensory stimulation). Our goal was to use an electrophysiological multisite network approach to investigate, in lightly anesthetised rats, the effects of a single psychotomimetic dose (2.5 mg/kg, subcutaneous) of ketamine on sensory stimulus-induced oscillations. Ketamine transiently increased the power of baseline beta/gamma oscillations and decreased sensory-induced beta/gamma oscillations. In addition, it disrupted information transferability in both the somatosensory thalamus and the related cortex and decreased the sensory-induced thalamocortical connectivity in the broadband gamma range. The present findings support the hypothesis that NMDA receptor antagonism disrupts the transfer of perceptual information in the somatosensory cortico-thalamo-cortical system.

Implementing an intravenous ketamine protocol for acute pain in the medical-surgical setting

ABSTRACT

A subanesthetic intravenous ketamine infusion is a safe and effective acute pain management modality for moderate to severely painful surgical procedures and may be useful in patients who are at increased risk for opioid-related adverse events. Despite its safety profile, intravenous ketamine is often restricted to the intensive care unit, which results in decreased patient access to this effective therapy. For clinicians who wish to implement an intravenous ketamine protocol in the medical-surgical setting, there are few resources available. In this brief report, we present our ketamine infusion protocol for acute pain and the clinical and financial outcomes 1 year after implementation. In our experience, ketamine infusions on the medical-surgical ward are safe and cost-effective when an established acute pain service protocol is followed. Nurse practitioners play an essential role in increasing patient access to intravenous ketamine infusions and leading change by collaborating with stakeholders to develop a protocol, training nurses and interdisciplinary team members, and providing ongoing support to nursing staff.

Utilization of Ketamine in Total Knee and Hip Joint Arthroplasty: An Evidence-Based Review

PURPOSE

To evaluate the efficacy of ketamine in total knee and hip arthroplasty.

DESIGN

Evidence-based review.

METHODS

Following the guidelines outlined in the PRISMA statement, a comprehensive search was conducted using Google Scholar, PubMed, CINAHL, Cochrane Collaboration, and other grey literature. Only randomized controlled studies and pre-appraised evidence such as systematic review and meta-analysis examining the effects of ketamine in total knee and hip arthroplasty were included. The quality appraisal of the literature was conducted using the proposed algorithm described in the Johns Hopkins Nursing Evidence-Based Practice Evidence Level and Quality Guide.

FINDINGS

Three systematic reviews and meta-analyses and 2 randomized controlled trials involving 1284 patients were included in this review. The use of ketamine reduced pain scores within the 24 hours after surgery. In addition, evidence suggests that patients who were treated with ketamine consumed fewer opioids 24 and 48 hours after surgery. Furthermore, ketamine reduced the incidence of postoperative nausea and vomiting with no effects on the incidence of hallucinations and central nervous system side effects. All studies included in the review were categorized as Level I and rated Grade A implying strong confidence in the true effects of ketamine in all outcome measures in the review.

CONCLUSIONS

The current evidence demonstrates the viability of ketamine as a safe and effective alternative to opioids in the perioperative setting with major total joint arthroplasty surgery. Decreased pain scores and opioid consumption up to 48 hours into the postoperative period were observed in a number of the appraised articles.

The effects of esketamine on the intestinal microenvironment and intestinal microbiota in mice

OBJECTIVE

This study aimed to investigate the impact of esketamine on the intestinal flora and microenvironment in mice using mRNA transcriptome sequencing and 16S rRNA sequencing.

METHODS

Ten female mice were randomly assigned to two groups. One group received daily intramuscular injections of sterile water, while the other group received esketamine. After 24 days, the mice were sacrificed, and their intestinal tissues and contents were collected for 16S rRNA sequencing and mRNA transcriptome sequencing. The intergroup differences in the mouse intestinal flora were analyzed. Differentially expressed genes were utilized to construct ceRNA networks and transcription factor regulatory networks to assess the effects of esketamine on the intestinal flora and intestinal tissue genes.

RESULTS

Esketamine significantly altered the abundance of intestinal microbiota, including Adlercreutzia equolifaciens and Akkermansia muciniphila. Differential expression analysis revealed 301 significantly upregulated genes and 106 significantly downregulated genes. The ceRNA regulatory network consisted of 6 lncRNAs, 44 miRNAs, and 113 mRNAs, while the regulatory factor network included 13 transcription factors and 53 target genes. Gene Ontology enrichment analysis indicated that the differentially expressed genes were primarily associated with immunity, including B-cell activation and humoral immune response mediation. The biological processes in the ceRNA regulatory network primarily involved transport, such as organic anion transport and monocarboxylic acid transport. The functional annotation of target genes in the TF network was mainly related to epithelial cells, including epithelial cell proliferation and regulation.

CONCLUSION

Esketamine induces changes in gut microbiota and the intestinal microenvironment, impacting the immune environment and transport modes.

Alternatives to remifentanil for the analgesic component of total intravenous anaesthesia: a narrative review

Propfol-remifentanil-based total intravenous anaesthesia has dominated recent clinical practice due to its favourable pharmacokinetic profile. Interruption in remifentanil supply has presented an opportunity to diversify or even avoid the use of opioids and consider adjuncts to propofol-based total intravenous anaesthesia. Propofol, while a potent hypnotic, is not an effective analgesic. The administration of opioids, along with other adjuncts such as α-2 adrenoceptor agonists, magnesium, lidocaine, ketamine and nitrous oxide provide surgical anaesthesia and avoids large doses of propofol being required. We provide an overview of both target-control and manual infusion regimes for the alternative opioids: alfentanil, sufentanil and fentanyl. The optimal combination of hypnotic-opioid dose, titration sequence and anticipated additional postoperative analgesia required depend on the chosen combination. In addition, we include a brief discussion on the role of non-opioid adjuncts in total intravenous anaesthesia, suggested doses and expected reduction in propofol dose.

A Perioperative Intervention to Prevent and Treat Emergence Delirium at a Veterans Affairs Medical Center

Emergence delirium (ED) is a temporary condition associated with a patient awakening from an anesthetic and/or adjunct agent (e.g., sedatives and analgesics). During the condition, patients risk harming themselves or staff by engaging in dangerous behavior, which may include thrashing, kicking, punching, and attempting to exit the bed/table. A multidisciplinary team at Veterans Affairs Pittsburgh Healthcare System (VAPHS) developed and implemented a multicomponent intervention to reduce the severity and occurrence of ED. The intervention consists of a training component and 21 clinical components. The 21 clinical components are implemented on a patient-by-patient basis and include routine screening for risk factors, enhanced communication among staff, adjusting the environment, following a specific medication strategy, and application of manual restraint (hands-on). The authors provide 15 online Supplemental Materials (S1–S15) to promote replication of the intervention. To our knowledge, this is the first manuscript that describes this type of multicomponent intervention in sufficient detail to allow others to replicate it. Following implementation of the intervention at VAPHS, perioperative staff reported that they observed a substantial reduction in the occurrence and severity of ED, ED-related patient and staff injuries, and ED-related loss of intravenous access and airway patency. Despite staff’s reported success of the intervention, rigorous research is needed to evaluate the efficacy of the intervention.

Online Supplement to “A Perioperative Intervention to Prevent and Treat Emergence Delirium at a Veteran Affairs Medical Center”

This supplementary material was provided by the authors to give readers additional information and resources to replicate their work.

Comparison of Ketamine, Dexmedetomidine and Lidocaine in Multimodal Analgesia Management Following Sleeve Gastrectomy Surgery: A Randomized Double-Blind Trial

PURPOSE

The aim of this study was to compare the effects of ketamine, dexmedetomidine, and lidocaine infusions added to the multimodal analgesia regimen on pain scores and analgesic requirement in laparoscopic sleeve gastrectomy.

DESIGN

A prospective randomized double-blind trial. Seventy-three patients aged 18 to 65 years (ASA II-III) undergoing laparoscopic sleeve gastrectomy were included. The patients were divided into 3 groups. Intravenous (IV) ketamine (0.5 mg/kg/h), dexmedetomidine (0.5 mcg/kg/h), and lidocaine (2 mg/kg/h) were administered to Groups K, D and L, respectively. Postoperative infusions were continued for 12 hours.

METHODS

Visual Analog Scale (VAS) scores (during rest and movement) in the admission to postanesthesia care unit, 1, 3, 6, 12, 24, 48 hours, and on day 15 were assessed postoperatively. Rescue analgesia requirement, the number of patients with nausea, retching, and vomiting, time to mobilization, and hospital length of stay (LOS) were recorded.

FINDINGS

VAS_rest values during all measurements in the first 24 hours, and VAS_movement values in the first 6 hours and at 24 hours were lower in Group L when compared to Group K and Group D (P < .001, P < .001, P = .008, respectively). VAS_rest at 48 hours and VAS_movement at 12 and 48 hours were lower in Group L when compared to Group K (P = .044, P = .001 and P = .011, respectively). There was no statistically significant difference between Group D compared to the other two groups at these times (P > .05). The requirement of rescue analgesia on postoperative day 1 was significantly higher in Group K (P < .001). Hospital LOS was shorter in Group L than in the other groups (P = .002).

CONCLUSIONS

IV lidocaine added to multimodal analgesia provided better pain control in the early postoperative period compared to dexmedetomidine and ketamine and decreased the hospital LOS.

Meta-analysis of the efficacy of ketamine in postoperative pain control in adolescent idiopathic scoliosis patients undergoing spinal fusion

PURPOSE

In this meta-analysis, we aim to compare ketamine use versus a control group (saline solution) during induction of anesthesia in adolescent idiopathic scoliosis patients undergoing fusion surgery in terms of postoperative opioid consumption, pain control, and side effects.

METHODS

A PubMed search of studies published over the last 20 years using the descriptor/terms "ketamine AND scoliosis" was performed. Baseline characteristics of each article were obtained and efficacy measures analyzed (morphine equivalent treatment at 24, 48, and 72 h postoperatively, complications (vomiting/nausea and pruritus), length of hospital stay (days); and pain score (VAS)) (Review Manager 5.4 software package).

RESULTS

Five randomized clinical trials were included. Morphine administration showed statistically significant differences at 24 and 48 h (MD - 0.15, 95% CI - 0.18 to - 0.12) and (MD - 0.26, 95% CI - 0.31 to - 0.21) between the ketamine and control (saline solution), respectively. No intergroup differences were found regarding nausea/vomiting and pruritus (OR 0.77, 95% CI 0.35 to 1.67) and (OR 0.71, 95% CI 0.31 to 1.62), respectively, same as for the pain score (MD - 0.75, 95% CI - 1.71 to 0.20).

CONCLUSIONS

The use intraoperative and postoperative continuous low doses of ketamine significantly reduces opioid use throughout the first 48 h in patients with AIS who undergo posterior spinal fusion.

Opioid-Free Anesthesia: The Pros and Cons

Appropriate perioperative pain control is essential to aid in patients' recovery after surgery; however, acute postsurgical pain remains poorly treated and there continues to be an overreliance on opiates. Perioperative pain control starts in the operating room, and opiate-free anesthesia (OFA), where no opiates are used intraoperatively, has been proposed as a feasible strategy to further minimize opiates in the perioperative period. In this article, we address the potential benefits and shortcomings of OFA, while exploring tools available to accomplish multimodal anesthesia and ideally OFA, and the evidence behind the techniques proposed.

Adverse Effects Associated with Patient-Controlled Analgesia with Ketamine Combined with Opioids and Ketamine Infusion with PCA Bolus in Postoperative Spine Patients: A Retrospective Review

Objective

There has been increasing use of ketamine at subanesthetic doses as an adjunct to opioids in perioperative pain management. There are several known adverse drug effects (ADEs) associated with ketamine. However, the incidence of ADEs with ketamine infusions with patient-controlled analgesia (PCA) boluses compared with combined opioid and ketamine PCAs is not well described. The objectives of this study were to compare the incidence and type of ADEs in postoperative spine surgery patients on ketamine infusions with as-needed PCA boluses to patients on combined opioid and ketamine PCAs.

Methods

The medical records of patients who underwent spine surgery between March 2016 and March 2020 who were postoperatively treated with a ketamine infusion and as-needed PCA boluses and parenteral opioids or treated with a combined opioid and ketamine PCA were reviewed. Perioperative information including patient characteristics and preoperative morphine equivalent daily dose (MEDD) were collected. Patient charts were reviewed for ADEs including psychological and neurological side effects, nausea, and new-onset tachycardia.

Results

A total of 315 patients met the inclusion criteria and were included in the final analysis. Of these patients, 121 experienced at least one ADE (38%). Sixteen of the 68 ketamine infusion with PCA bolus patients (24%), 77 of the 203 hydromorphone and ketamine patients (38%), and 28 of the 44 morphine and ketamine patients (64%) experienced an ADE [p<0.01]. In patients with preoperative MEDD ≤ 90, nausea was the only ADE that differed significantly among the three groups.

Conclusion

This retrospective analysis suggests that postoperative spine patients treated with a ketamine infusion with as-needed PCA boluses and parenteral opioids were associated with fewer ADEs when compared to an intravenous combined opioid and ketamine PCA. In patients with preoperative MEDD ≤ 90, nausea with and without emesis was the only ADE that showed statistically significant difference amongst the three groups.

Perfusion index as a predictor of working pediatric caudal block under general anesthesia- A prospective observational study

Background and Aims

Advances in pulse oximeter technology have enabled us to measure parameters such as perfusion index (PI). We aimed to ascertain the utility of PI in the lower limb for evaluating the onset and adequacy of the pediatric caudal block under general anesthesia. The primary objective was to monitor PI trends after caudal block. The secondary objective was to compare the role of PI, heart rate (HR), and mean arterial pressure (MAP) in detecting onset and adequacy of caudal block and to ascertain whether PI was an earlier indicator in detecting adequate block.

Material and Methods

Twenty-five children between 1 and 6 years, who underwent general anesthesia (GA) with caudal block were included. Baseline PI, HR, and MAP were recorded prior to and post caudal block at 5, 10, 15, 20 min and on skin incision. The onset of adequate block was defined as 100% increase of PI from baseline, 15% decrease of MAP or HR from baseline. T-test was used to compare trends of PI with baseline and the number of patients who met or failed these criteria for each of these three parameters at various time intervals wasnoted.

Results

PI increased at all time intervals in 23 of 25 patients with working caudal block (P < 0.0001). By 10 min all those with a working caudal showed a 100% increase in PI. In contrast, 15% decrease in HR was not attained until 15 min where only 8 out of 23 achieved the above criteria, reaching a maximum of 20 patients at the time of incision; a 15% decrease in MAP was observed only in one patient at 5 min, reaching a maximum of eight patients at the time of incision.

Conclusion

PI is an earlier and more sensitive indicator of the onset of the caudal block under general anesthesia (GA) than HR and MAP.

Postoperative pain management in non-traumatic emergency general surgery: WSES-GAIS-SIAARTI-AAST guidelines

BACKGROUND

Non-traumatic emergency general surgery involves a heterogeneous population that may present with several underlying diseases. Timeous emergency surgical treatment should be supplemented with high-quality perioperative care, ideally performed by multidisciplinary teams trained to identify and handle complex postoperative courses. Uncontrolled or poorly controlled acute postoperative pain may result in significant complications. While pain management after elective surgery has been standardized in perioperative pathways, the traditional perioperative treatment of patients undergoing emergency surgery is often a haphazard practice. The present recommended pain management guidelines are for pain management after non-traumatic emergency surgical intervention. It is meant to provide clinicians a list of indications to prescribe the optimal analgesics even in the absence of a multidisciplinary pain team.

MATERIAL AND METHODS

An international expert panel discussed the different issues in subsequent rounds. Four international recognized scientific societies: World Society of Emergency Surgery (WSES), Global Alliance for Infection in Surgery (GAIS), Italian Society of Anesthesia, Analgesia Intensive Care (SIAARTI), and American Association for the Surgery of Trauma (AAST), endorsed the project and approved the final manuscript.

CONCLUSION

Dealing with acute postoperative pain in the emergency abdominal surgery setting is complex, requires special attention, and should be multidisciplinary. Several tools are available, and their combination is mandatory whenever is possible. Analgesic approach to the various situations and conditions should be patient based and tailored according to procedure, pathology, age, response, and available expertise. A better understanding of the patho-mechanisms of postoperative pain for short- and long-term outcomes is necessary to improve prophylactic and treatment strategies.

Identifying Patients Vulnerable to Inadequate Pain Resolution After Cardiac Surgery

Acute postoperative pain (APOP) is often evaluated through granular parameters, though monitoring postoperative pain using trends may better describe pain state. We investigated acute postoperative pain trajectories in cardiac surgical patients to identify subpopulations of pain resolution and elucidate predictors of problematic pain courses. We examined retrospective data from 2810 cardiac surgical patients at a single center. The k-means algorithm for longitudinal data was used to generate clusters of pain trajectories over the first 5 postoperative days. Patient characteristics were examined for association with cluster membership using ordinal and multinomial logistic regression. We identified 3 subgroups of pain resolution after cardiac surgery: 37.7% with good resolution, 44.2% with moderate resolution, and 18.2% exhibiting poor resolution. Type I diabetes (2.04 [1.00-4.16], p = 0.05), preoperative opioid use (1.65 [1.23-2.22], p = 0.001), and illicit drug use (1.89 [1.26-2.83], p = 0.002) elevated risk of membership into worse pain trajectory clusters. Female gender (1.72 [1.30-2.27], p < 0.001), depression (1.60 [1.03-2.50], p = 0.04) and chronic pain (3.28 [1.79-5.99], p < 0.001) increased risk of membership in the worst pain resolution cluster. This study defined 3 APOP resolution subgroups based on pain score trend after cardiac surgery and identified factors that predisposed patients to worse resolution. Patients with moderate or poor pain trajectory consumed more opioids and received them for longer before discharge. Future studies are warranted to determine if altering postoperative pain monitoring and management improve postoperative course of patients at risk of moderate or poor pain resolution.

Multimodal Analgesia

Perioperative pain management is one of the domains in which Anesthesiologists are intricately involved, and which is immensely important. Adequate postoperative analgesia is central to avoid both the acute as well as chronic complications of uncontrolled postoperative pain. Preventive analgesia has been identified as an approach to mitigate the phenomenon of central sensitization, which plays an important role in the development of chronic pain after surgery. As an over-reliance on opioids for peri- and postoperative pain control is associated with opioid dependence and hyperalgesia, multimodal analgesia has taken center stage. Multimodal analgesia, in theory, will optimize perioperative pain control, reduce the chance of central sensitization, and avoid the detrimental effects of opioid overuse. Multiple classes of systemic analgesic medications have been used to accomplish these tasks, and the aim of this article is to outline these medications, their mechanisms of action, as well as the evidence behind their individual roles in multimodal analgesia. Regional anesthesia has also been embraced as a key component of multimodal analgesia in orthopedic surgery; however, over the past several years, local infiltration analgesia (LIA) emerged as a viable alternative, particularly in total knee arthroplasty.