Role of ketamine in acute postoperative pain management: a narrative review

Adding Ketamine to Epidural Morphine Does Not Prolong Postoperative Analgesia After Lumbar Laminectomy or Discectomy

BACKGROUND

Epidural opioids provide effective postoperative analgesia after lumbar spine surgery. Ketamine has been shown to reduce opioid-induced central sensitization and hyperalgesia. We hypothesized that adding ketamine to epidural opioids would prolong the duration of analgesia and enhance analgesic efficacy after lumbar spine surgery.

METHODS

American Society of Anesthesiologists physical status class I to II patients aged between 18 and 70 years with normal renal function undergoing lumbar laminectomy were recruited into this single-center randomized trial. Patients were randomized to receive either single-dose epidural morphine (group A) or epidural morphine and ketamine (group B) for postoperative analgesia. The primary objective was to compare the duration of analgesia as measured by time to the first postoperative analgesic request. Secondary objectives were the comparison of pain scores at rest and movement, systemic hemodynamics, and the incidence of side effects during the first 24 hours after surgery.

RESULTS

Fifty patients were recruited (25 in each group), of which data from 48 were available for analysis. The mean±SD duration of analgesia was 20±6 and 23±3 hours in group A and group B, respectively ( P =0.07). There were 12/24 (50%) patients in group A and 17/24 (71%) patients in group B who did not receive rescue analgesia during the first 24-hour postoperative period ( P =0.07). Pain scores at rest and movement, systemic hemodynamics, and postoperative complications were comparable between the groups.

CONCLUSIONS

The addition of ketamine to epidural morphine did not prolong the duration of analgesia after lumbar laminectomy.

Opioid Utilization After Scoliosis Surgery is Greater in Marfan Syndrome Than Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective matched case cohort.

OBJECTIVE

Compare postoperative opioid utilization and prescribing behaviors between patients with Marfan syndrome (MFS) and adolescent idiopathic scoliosis (AIS) after posterior spinal fusion (PSF).

SUMMARY OF BACKGROUND DATA

Opioids are an essential component of pain management after PSF. However, due to the potential for opioid use disorder and dependence, current analgesic strategies aim to minimize their use, especially in younger patients. Limited information exists on opioid utilization after PSF for syndromic scoliosis.

PATIENTS AND METHODS

Twenty adolescents undergoing PSF with MFS were matched with patients with AIS (ratio, 1:2) by age, sex, degree of spinal deformity, and the number of vertebral levels fused. Inpatient and outpatient pharmaceutical data were reviewed for the quantity and duration of opioid and adjunct medications. Prescriptions were converted to morphine milligram equivalents (MMEs) using CDC's standard conversion factor.

RESULTS

Compared with patients with AIS, patients with MFS had significantly greater total inpatient MME use (4.9 vs . 2.1 mg/kg, P ≤ 0.001) and longer duration of intravenous patient-controlled anesthesia (3.4 vs . 2.5 d, P = 0.001). Within the first 2 postop days, MFS patients had more patient-controlled anesthesia boluses (91 vs . 52 boluses, P = 0.01) despite similar pain scores and greater use of adjunct medications. After accounting for prior opioid use, MFS was the only significant predictor of requesting an opioid prescription after discharge (odds ratio: 4.1, 95% CI: 1.1-14.9, P = 0.03). Patients with MFS were also more likely to be discharged with a more potent prescription (1.0 vs . 0.72 MME per day/kg, P ≤ 0.001) and to receive a longer-duration prescription (13 vs . 8 d, P = 0.005) with a greater MME/kg (11.6 vs . 5.6 mg/kg, P ≤ 0.001) as outpatients.

CONCLUSION

Despite a similar intervention, patients with MFS and AIS seem to differ in their postoperative opioid usage after PSF, presenting an opportunity for further research to assist clinicians in better anticipating the analgesic needs of individual patients, particularly in light of the ongoing opioid epidemic.

Efficacy of memantine premedication in alleviating postoperative pain- A systematic review and meta-analysis

Many premedication agents with opioid-sparing properties have been used in patients undergoing various elective surgeries. Memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist that has been used by many researchers as an opioid-sparing strategy. Various databases like PubMed, Scopus, Cochrane Library, and clinicaltrials.gov were searched after registering the review protocol in PROSPERO for randomized-controlled trials (RCTs) that investigated the efficacy and safety of memantine premedication in adult patients undergoing various elective surgeries. The risk of bias (RoB-2) scale was used to assess the quality of evidence. From the 225 articles that were identified after a database search, 3 studies were included for a qualitative systematic review and a quantitative meta-analysis. The pooled analysis revealed that the use of memantine provided better pain scores at 2nd (mean difference: -0.82, 95% CI: -1.60, -0.05, P = 0.04) with significant heterogeneity (P = 0.06; I² =71%), and 6 hours postoperatively (mean difference: -1.80, 95% CI: -2.23, -1.37, P < 0.00001), but not at 1 hour. The sedation scores at 1 hour were higher in the memantine group but comparable in the 2nd hour. The number of doses of rescue analgesia and nausea/vomiting in the postoperative period was comparable in both groups. The results of this review suggest that memantine premedication could provide better pain scores in the immediate postoperative period with acceptable adverse effects. However, the current evidence is insufficient to suggest the routine use of memantine as a premedication before elective surgeries.

A pre-anesthetic bolus of ketamine versus dexmedetomidine for prevention of postoperative delirium in elderly patients undergoing emergency surgery: a randomized, double-blinded, placebo-controlled study

BACKGROUND

We aimed to evaluate whether a single dose of ketamine or dexmedetomidine before induction of general anesthesia could reduce the incidence of postoperative delirium (primary outcome) or cognitive dysfunction (secondary outcome) in elderly patients undergoing emergency surgery.

PATIENTS AND METHODS

This randomized, double-blinded, placebo-controlled trial included 60 elderly patients who were scheduled for emergency surgery. The patients were randomly assigned into one of three groups (n = 20): group I received 0.9% normal saline, group II received 1 µg/kg dexmedetomidine, and group III received 1 mg/kg ketamine right before anesthesia induction. Patients were observed for three days after surgery and tested for postoperative delirium and cognitive dysfunction using the delirium observation screening scale and the mini-mental state examination score, respectively.

RESULTS

The dexmedetomidine group had the lowest incidence of delirium (p = 0.001) and cognitive dysfunction (p = 0.006) compared to the ketamine and placebo groups. The multivariate logistic regression model revealed that dexmedetomidine reduced the incidence of postoperative delirium by 32% compared to placebo (reference) (OR = 0.684, 95% CI: 0.240-0.971, p = 0.025), whereas ketamine increased the risk by threefold (OR = 3.012, 95% CI: 1.185-9.681, p = 0.013). Furthermore, dexmedetomidine reduced the incidence of postoperative cognitive dysfunction by 62% (OR = 0.375, 95% CI: 0.091-0.543, p = 0.012), whereas ketamine increased the risk by 4.5 times (OR = 4.501, 95% CI: 1.161-8.817, p = 0.006).

CONCLUSION

A single pre-anesthetic bolus of dexmedetomidine is a practical choice for preventing postoperative delirium in elderly patients undergoing emergency surgery.

TRIAL REGISTRATION

This study was approved by the Ethics Committee of Aswan University Hospital (approval number: aswu/548/7/2021; registration date: 06/07/2021) and registered on ClinicalTrials.gov (NCT05341154) (22/04/2022).

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.

Rectus Sheath Block Improves Patient Recovery Following Open Aortic Surgery

BACKGROUND

Postoperative pain management remains a barrier to recovery following aortic surgery. Although epidural catheters help in adjunctive pain management, less is known about the use of rectus sheath blocks. We compared patient recovery following open abdominal aortic surgery (OAS) with and without adjunctive rectus block.

METHODS

Adult patients undergoing open abdominal aortic aneurysm repair and aortobifemoral or aortoiliac bypass for occlusive disease were identified and stratified by use of general anesthesia alone (GA) versus adjunctive use of a rectus sheath block (GA + RB). A small number of patients with GA and concomitant epidural analgesia, along with patients that had retroperitoneal repairs, were not included in further analysis. Outcomes included time to extubation, intraoperative and postoperative morphine milligram equivalents (MME) utilization, length of stay, discharge MME, and postoperative complications. Categorial data were compared with Person Chi-Square tests or Fisher's exact tests. Continuous data were tested with independent t-tests or Mann-Whitney U-tests.

RESULTS

From January 2017 to April 2022, there were 106 patients who underwent open aortic surgery, 55 patients with GA alone, 39 with GA + RB, and 12 patients who had a GA with concomitant epidural analgesia. Between GA and GA + RB, patients were comparable in both groups in terms of age, BMI (body mass index), smoking history, hypertension, diabetes, CAD (coronary artery disease), COPD (chronic obstructive pulmonary disease), and ASA (American Society of Anesthesiologists) class and prior opioid use. Patients with GA + RB were more likely to have scheduled elective procedures (80% GA cohort vs. 94.9% RB, P = 0.040), and a lower incidence of retroperitoneal exposure (14.5% GA cohort vs. 0% RB, P = 0.019). Patients with GA + RB had shorter time to extubation than GA (84.6% < 12 hr vs. 44.4%, P < 0.001), greater rate of procedural ketamine usage (GA + RB: 61.5% vs. GA: 40.0%, P = 0.049), lower MME at first postoperative day (median MME GA + RB: 25.0 vs. GA: 67.5, P = 0.002), lower discharge MME (median MME GA + RB: 142.5 vs. GA: 225.0, P = 0.036), and overall shorter length of stay (median stay GA + RB: 5 vs. GA: 6 days, P = 0.006). Postoperative complications were similar between groups. Similar findings were found in the comparison between elective-only GA and GA + RB patients and after exclusion of patients who only had a single shot of regional anesthesia.

CONCLUSIONS

Patients that receive adjunctive rectus sheath blocks for pain control following OAS utilize fewer opioid medications during hospital stay and at discharge. Rectus sheath blocks represent an alternative option to other periprocedural analgesia following open aortic surgery.

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.

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.

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.

Acute Pain Management Pearls: A Focused Review for the Hospital Clinician

Acute pain management is a challenging area encountered by inpatient clinicians every day. While patient care is increasingly complex and costly in this realm, the availability of applicable specialists is waning. This narrative review seeks to support diverse hospital-based healthcare providers in refining and updating their acute pain management knowledge base through clinical pearls and point-of-care resources. Practical guidance is provided for the design and adjustment of inpatient multimodal analgesic regimens, including conventional and burgeoning non-opioid and opioid therapies. The importance of customized care plans for patients with preexisting opioid tolerance, chronic pain, or opioid use disorder is emphasized, and current recommendations for inpatient management of associated chronic therapies are discussed. References to best available guidelines and literature are offered for further exploration. Improved clinician attention and more developed skill sets related to acute pain management could significantly benefit hospitalized patient outcomes and healthcare resource utilization.

Bibliometric and Visual Analysis of the Current Status and Trends of Postoperative Pain in Children from 1950-2021

Background

Postoperative pain in children has been overlooked for a long time. The knowledge structure, research hotspots and trends related to postoperative pain in children are unclear and have not been systematically summarized.

Purpose

We aimed to analyze the current state of research on postoperative pain in children and to conduct in-depth mining of the knowledge structure.

Methods

The PubMed database for publications on postoperative pain in children between 1950 and 2021 was searched. Bibliographic Item Co-Occurrence Matrix Builder (BICOMB) was performed to obtain the co-word matrix and co-occurrence matrix. The H-index method was used to extract high-frequency main Medical Subject Headings (MeSH) terms/subheadings.

Results

The high-frequency MeSH terms were analyzed by biclustering, strategic diagram and social network analyses. Totally, 4022 publications were retrieved. The analysis showed that 60 countries or regions published relevant documents, with the United States publishing the most significant number of papers. Totally, 811 journals published relevant papers, with Pediatric Anesthesia ranking first. Moreover, we extracted 43 high-frequency main MeSH terms/subheadings and clustered them into five categories: overview, aetiology and epidemiology, pharmacotherapy, opioid administration and dosing, and prevention and control of postoperative pain in children.

Conclusion

Pharmacological treatments, pain prevention and control are the focus of research and are becoming increasingly mature. Opioid stewardship and regional anesthesia is the trend and focus of future research. Our study offers a better understanding of the current status and knowledge structure of postoperative pain in children and provides a reference for improving postoperative pain management in children in the future.

Efficacy and safety of wound infiltration modalities for postoperative pain management after cesarean section: a systematic review and network meta-analysis protocol

BACKGROUND

Postoperative pain after a cesarean section has negative consequences for the mother during the postoperative period. Over the years, various postoperative pain management strategies have been used following cesarean section. Opioid-based analgesics and landmark approaches have negative side effects, while ultrasound-based regional analgesia necessitates resources and experience, but various wound infiltration adjuvants are innovative with few side effects and are simple to use. The efficacy and safety of each adjuvant, however, are unknown and require further investigation.

OBJECTIVE

This network meta-analysis is intended to provide the most effective wound infiltration drugs for postoperative management after cesarean section.

METHOD

A comprehensive search will be conducted in PubMed/MEDLINE, Cochrane Library, Science Direct, CINHAL, and LILACS without date and language restrictions. All randomized trials comparing the effectiveness of wound infiltration drugs for postoperative pain management after cesarean section will be included. Data extraction will be conducted independently by two authors. The quality of studies will be evaluated using the Cochrane risk of bias tool, and the overall quality of the evidence will be determined by GRADEpro software.

DISCUSSION

The rate of postoperative acute and chronic pain is very high which has a huge impact on the mother, family, healthcare practitioners, and healthcare delivery. It is a basic human right to give every patient with postoperative pain treatment that is realistic in terms of resources, technique, cost, and adverse event profile.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021268774.

Implementation of a standardized multimodal pain regimen significantly reduces postoperative inpatient opioid utilization in patients undergoing bariatric surgery

BACKGROUND

Routine opioid use in surgical patients has received attention given the opioid epidemic and a renewed focus on the dangers and drawbacks of opioids in the postoperative setting. Little is known about opioid use in bariatric surgery, especially in the inpatient setting. We hypothesize that a standardized opioid-sparing protocol reduces postoperative inpatient opioid use in bariatric surgery patients.

METHODS

A retrospective cohort study was conducted of bariatric surgery patients at a single institution. From March to September 2019, a standardized intraoperative and postoperative opioid-sparing protocol was designed and implemented along with an educational program for patients regarding safe pain management. Inpatient opioid utilization in patients undergoing surgery in the preintervention phase between April and March 2019 was compared to patients from a postintervention phase of October 2019 to December 2020. Opioid utilization was measured in morphine milliequivalents (MME).

RESULTS

A total of 359 patients were included; 192 preintervention and 167 postintervention. Patients were similar demographically. For all patients, mean age was 44.1 years, mean BMI 49.2 kg/m2, and 80% were female. Laparoscopic sleeve gastrectomy was performed in 48%, laparoscopic gastric bypass in 34%, robotic sleeve gastrectomy in 17%, and robotic gastric bypass in 1%. In the postintervention phase inpatient opioid utilization was significantly lower [median 134.8 [79.0-240.8] MME preintervention vs. 61.5 [35.5-150.0] MME postintervention (p < 0.001)]. MME prescribed at discharge decreased from a median of 300 MME preintervention to 75 MME postintervention (p < 0.001). In the postintervention phase, 16% of patients did not receive an opioid prescription at discharge compared to 0% preintervention (p < 0.001). When examining by procedure, statistically significant reductions in opioid utilization were seen for each operation.

CONCLUSION

Implementation of a standardized intraoperative and postoperative multimodal pain regimen and educational program significantly reduces inpatient opioid utilization in patients undergoing bariatric surgery.

Ketamine and Its Emergence in the Field of Neurology

The quest for a safe and effective anesthetic medication in the mid-20th century led to the discovery of CI-581, which was later named ketamine. Ketamine was labeled a “dissociative anesthetic” due to the state of sensory deprivation that it induces in the subjects receiving it. Although it enjoyed widespread use at the beginning of the Vietnam war, its use rapidly waned due to its psychedelic effect and it became more popular as a recreational drug, and in the field of veterinary medicine. However, as we gained more knowledge about its multiple sites of action, it has reemerged as a useful anesthetic/analgesic agent. In the last decade, the field of neurology has witnessed the growing use of ketamine for the treatment of several neurological conditions including migraine, status epilepticus, stroke, and traumatic brain injury (TBI). Ketamine acts primarily as a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. The binding of ketamine to NMDA receptors leads to decreased frequency and duration of Ca⁺² channel opening and thus inhibits glutaminergic transmission. This mechanism has proven to be neuroprotective in several neurological conditions. Ketamine does not increase intracranial pressure (ICP), and it maintains cerebral perfusion pressure (CPP) by increasing cerebral blood flow. Ketamine has also been shown to inhibit massive slow waves of neurological depolarizations called cortical spreading depolarizations (CSD), usually seen during acute neurological injury and are responsible for further neurological deterioration. Unlike other anesthetic agents, ketamine does not cause cardiac or respiratory suppression. All these favorable mechanisms and cerebral/hemodynamic actions have led to increased interest among clinicians and researchers regarding the novel uses of ketamine. This review will focus on the use of ketamine for various neurological indications.

Pain and Multimodal Analgesia in Laparoscopic Cholecystectomy

Background: The administration of high doses of opioids during surgery can lead to higher postoperative pain scores at rest and when coughing. Multimodal analgesia may lower the need for opioids during surgery and the suffering of postoperative pain. Multimodal analgesia can be achieved by providing non-opioid drugs (lidocaine, ketamine, and magnesium sulfate), three different types of drugs. Each of these drugs as different analgesic effects and they belong to three different pharmacological groups. The aim of this study is to develop a better understanding of the effects of each drug (lidocaine, ketamine, and magnesium sulfate) on postoperative analgesia, the needs for rescue analgesics, and analyze the total amount of fentanyl during the intraoperative period in patients undergoing laparoscopic cholecystectomy. Methods: 120 patients were enrolled in this randomized controlled study. They were classified as ASA 1 and 2 and were scheduled for laparoscopic cholecystectomy. They were further divided into 3 groups. Group 1, or the lidocaine group, had received lidocaine at 1 mg/kg and a continuous intravenous infusion with lidocaine at 2 mg/kg/h. Group 2, or the ketamine group, received ketamine at 0.5 mg/kg. Group 3, or the magnesium sulfate group, received a continuous intravenous infusion of magnesium sulfate at 1.5 gr/kg. The intensity of postoperative pain was assessed using a VAS score at rest and when coughing, with evaluation at 1, 4, 8, 12, and 24 hours, postoperatively. Also, the needs for rescue analgesics and the total amount of fentanyl during the intraoperative period in all groups was also followed. Results: The patients from the lidocaine group had the highest scores of pain in the postoperative period at rest and when coughing, and the ketamine group had the lowest pain scores. Rescue analgesia was given the most to lidocaine group, and less so in the magnesium group. The magnesium group received the highest dose of fentanyl during surgery and the lowest dose was received by patients from the lidocaine group. Conclusion: Multimodal analgesia can lower the need for opioids in the intra- and postoperative period after laparoscopic cholecystectomy.

Statistical Fragility of Ketamine Infusion during Scoliosis Surgery to Reduce Opioid Tolerance and Postoperative Pain

OBJECTIVE

Randomized controlled trials (RCTs) have come under scrutiny due to a frequent lack of reproducibility, due in part to shortcomings of the common p<0.05 threshold for significance. Here, we utilize fragility indices to assess the statistical robustness of RCTs evaluating low-dose ketamine during scoliosis surgery to reduce opioid tolerance and postoperative pain.

METHODS

RCTs evaluating outcomes after intraoperative ketamine infusion in adolescent idiopathic scoliosis (AIS) patients were included. Relevant outcomes included pain, opioid consumption, quality of life, anesthesia, sedation, adverse effects, and length of stay. The dichotomous or continuous fragility index (FI or CFI) was determined by manipulating each outcome event until reversal of significance (a=0.05) was achieved. The corresponding fragility quotients (FQ) were calculated by dividing the FI or CFI by the sample size.

RESULTS

Of 27 studies screened, 6 studies (61 outcome events) were included. The median FI for dichotomous events was 2.0 (FQ=0.045), suggesting that altering the outcome of only 2 patients (or 4.5 out of 100) would reverse trial significance. For continuous events, altering the treatment of only 6 patients (or 14.1 out of 100) would reverse significance. Outcome events that were originally reported as significant (p<0.05) were considerably more fragile (FI=1.5; CFI=3.5) than events that were reported as nonsignificant (FI=2.0; CFI=7.0).

CONCLUSIONS

While evidence for ketamine use is promising, our fragility analysis suggests that RCT findings may be underpowered in some cases. Given the importance of RCTs in clinical decision-making, fragility indices should be reported alongside p-values to indicate the strength of statistical findings.

Considerations for Better Management of Postoperative Pain in Light of Chronic Postoperative Pain: A Narrative Review

Chronic postoperative pain (CPOP) is prevalent, with particularly high rates in breast surgery, thoracotomy, and amputation. As the world emerges from the coronavirus disease 2019 (COVID-19) lockdowns, it is expected that there will be an increase in surgical procedures, elevating the importance of preventing CPOP in the coming years. Risk factors are emerging to better stratify patients at high risk for CPOP. Perioperative analgesia plays an important role in managing acute postoperative pain and in some cases may limit its transition to CPOP. Acute postoperative pain is adaptive, normal, expected, and has a well-defined trajectory, while CPOP is maladaptive and, as a form of chronic pain, is challenging to treat. Good analgesia, early ambulation, and rehabilitation efforts may be helpful in preventing CPOP following certain surgeries. Enhanced Recovery After Surgery (ERAS) protocols present guidance to help promote recovery and prevent CPOP.

Three Birds, One Excipient: Development of an Improved pH, Isotonic, and Buffered Ketamine Formulation for Subcutaneous Injection

Subcutaneous (SC) ketamine has been found to be effective in pain management, though reports of injection site irritation and sterile abscesses exist with currently available ketamine HCl formulations. Such adverse SC reactions are commonly associated with low pH, high osmolality and/or high injection volumes. An optimal SC formulation of ketamine would thus have a pH and osmolality close to physiological levels, without compromising on concentration and, thus, injection volume. Such a formulation should also be buffered to maintain the pH at the acceptable level for extended time periods. As many of these physicochemical properties are interrelated, achieving these aims represented a significant challenge in formulation development. We describe the development of a novel Captisol^®-based formulation strategy to achieve an elevated pH, isosmotic and buffered formulation of ketamine (hence, three birds, one excipient) without compromising on concentration. This strategy has the potential to be readily adapted to other amine-based APIs.

Interactions between Ketamine and Magnesium for the Treatment of Pain: Current State of the Art

BACKGROUND

Over the past three decades, NMDA-receptor antagonists have been shown to be efficient drugs for treating pain, particularly pain resistant to conventional analgesics. Emphasis will be on the old-new drugs, ketamine and magnesium, and their combination as a novel approach for treating chronic pain.

METHODS

The MEDLINE database was searched via PubMed for articles that were published up to March 1, 2020, with the keywords 'ketamine', 'magnesium', and 'pain' (in the title/abstract).

RESULTS

Studies in animals, as well as humans, have shown that interactions of ketamine and magnesium can be additive, antagonistic, and synergistic. These discrepancies might be due to differences in magnesium and ketamine dosage, administration times, and the chronological order of drug administration. Different kinds of pain can also be the source of divergent results.

CONCLUSION

This review explains why studies performed with a combination of ketamine and magnesium have given inconsistent results. Because of the lack of efficacy of drugs available for pain, ketamine and magnesium in combination provide a novel therapeutic approach that needs to be standardized with a suitable dosing regimen, including the chronological order of drug administration.

Prevention of Acute Postoperative Pain in Breast Cancer: A Comparison between Opioids versus Ketamine in the Intraoperatory Analgesia

Background

Acute postoperative pain (APP) has a high incidence in breast surgery, and opioids are the most commonly used drugs for its management; however, they are not free from systemic side effects, which may increase comorbidity. In the past few years, opioid-free anaesthesia has been favoured with promising results.

Methods

We conducted a descriptive study including 71 patients who underwent breast cancer surgery. The opioid group (n = 41) received fentanyl for induction, remifentanil for maintenance, and rescue morphine before waking up, whereas the ketamine group (n = 30) received a ketamine bolus for induction followed by continuous ketamine infusion during surgery. Later, the presence and intensity of pain were registered, using the Numeric Rating Scale (NRS 1-10) for pain, at different times in the recovery room, at 24 hours and at 3 months.

Results

Administration of ketamine is more effective than opioid use for APP prevention in breast cancer surgery because the ketamine group presented with less pain than the opioid group (p < 0.05) at all measured times. When there was pain, patients in the ketamine group gave a lower score to its intensity (p < 0.05).

Conclusions

Ketamine could reduce the incidence of APP in breast cancer surgery, compared to opioids.

Impact of Intraoperative Ketamine on Postoperative Analgesic Requirement Following Bariatric Surgery: a Meta-analysis of Randomized Controlled Trials

This meta-analysis aimed at exploring the impact of intravenous ketamine on pain relief and analgesic consumption in patients undergoing bariatric surgery (BS). Literature searches identified nine eligible trials with 458 participants. Forest plot revealed a significantly lower pain score [mean difference (MD) =  - 1.06, p = 0.005; 390 patients) and morphine consumption (MD =  - 3.85 mg, p = 0.01; 212 patients) immediately after BS in patients with intravenous ketamine than in those without. In contrast, pooled analysis showed comparable pain score (p = 0.28), morphine consumption (p = 0.45) within 24 h, and risk of postoperative nausea/vomiting (p = 0.67) between the two groups. In conclusion, the meta-analysis demonstrated improvements in pain outcomes immediately after surgery through perioperative intravenous ketamine administration despite the absence of analgesic benefit in the late postoperative period and a positive impact on postoperative nausea/vomiting.

Adjunctive ketamine for sedation in critically ill mechanically ventilated patients: an active-controlled, pilot, feasibility clinical trial

OBJECTIVE

Ketamine has been shown to decrease sedative requirements in intensive care unit (ICU). Randomized trials are limited on patient-centered outcomes. We designed this pilot trial to evaluate the feasibility of a large randomized controlled trial (RCT) testing the effect of ketamine as an adjunct analgosedative compared with standard of care alone as a control group (CG) in critically ill patients with mechanical ventilation (MV). We also provided preliminary evidence on clinically relevant outcomes to plan a larger trial.

MATERIAL AND METHODS

Pilot, active-controlled, open-label RCT was conducted at medical, surgical, and transplant ICUs at a large tertiary and quaternary care medical institution (King Faisal Specialist Hospital and Research Center, Saudi Arabia). The study included adult patients who were intubated within 24 h, expected to require MV for the next calendar day, and had institutional pain and sedation protocol initiated. Patients were randomized in a 1:1 ratio to adjunct ketamine infusion 1-2 μg/kg/min for 48 h or CG alone.

RESULTS

Of 437 patients screened from September 2019 through November 2020, 83 (18.9%) patients were included (43 in CG and 40 in ketamine) and 352 (80.5%) were excluded. Average enrollment rate was 3-4 patients/month. Consent and protocol adherence rates were adequate (89.24% and 76%, respectively). Demographics were balanced between groups. Median MV duration was 7 (interquartile range [IQR] 3-9.25 days) in ketamine and 5 (IQR 2-8 days) in CG. Median VFDs was 19 (IQR 0-24.75 days) in ketamine and 19 (IQR 0-24 days) in the CG (p = 0.70). More patients attained goal Richmond Agitation-Sedation Scale at 24 and 48 h in ketamine (67.5% and 73.5%, respectively) compared with CG (52.4% and 66.7%, respectively). Sedatives and vasopressors cumulative use, and hemodynamic changes were similar. ICU length-of-stay was 12.5 (IQR 6-21.2 days) in ketamine, compared with 12 (IQR 5.5-23 days) in CG. No serious adverse events were observed in either group.

CONCLUSIONS

Ketamine as an adjunct analgosedative agent appeared to be feasible and safe with no negative impact on outcomes, including hemodynamics. This pilot RCT identified areas of improvement in study protocol before conducting a large, adequately powered, multicenter RCT which is likely justified to investigate ketamine association with patient-centered outcomes further. Trial registration ClinicalTrials.gov: NCT04075006. Registered on 30 August 2019. Current controlled trials: ISRCTN14730035. Registered on 3 February 2020.

Ketamine for Acute Pain Management and Sedation

TOPIC

Ketamine is beneficial in clinical settings ranging from procedural sedation to the treatment of chronic pain. This article describes the clinical benefits of ketamine for treatment of acute pain and for sedation of patients undergoing mechanical ventilation.

CLINICAL RELEVANCE

Ketamine causes analgesic and amnestic effects by noncompetitive inhibition of the N-methyl-D-aspartate receptor and activation of the opioid μ and κ receptors. Unlike other sedatives, ketamine provides analgesia and amnesia without causing hypotension or respiratory depression. Several studies have elucidated the clinical benefits of ketamine. The use of ketamine has extended beyond critical care areas such as the operating room and intensive care units. Nurses must be familiar with optimal clinical scenarios, monitoring parameters, and contraindications of ketamine.

PURPOSE

To highlight the clinical utility and pharmacological properties of ketamine through a literature review. Current studies of ketamine in acute pain and sedation management are summarized.

CONTENT COVERED

This narrative review describes pharmacological properties, dosing strategies, adminis-tration considerations, and adverse effects of ketamine.

The multiple faces of ketamine in anaesthesia and analgesia

Objective

Ketamine is an anaesthetic agent with a unique dissociative profile and pharmacological effects ranging from the induction and maintenance of anaesthesia to analgesia and sedation, depending on the dose. This article provides information for the clinical use of ketamine in anaesthesia, in both conventional and special circumstances.

Methods

This is a non-systematic review of the literature, through a PubMed search up to February 2021.

Results

With a favourable pharmacokinetic profile, ketamine is used in hospital and prehospital settings for emergency situations. It is suitable for patients with many heart conditions and, unlike other anaesthetics, its potential for cardiorespiratory depression is low. Furthermore, it may be used when venous access is difficult as it may be administered through various routes. Ketamine is the anaesthetic of choice for patients with bronchospasm thanks to its bronchodilatory and anti-inflammatory properties.

Conclusion

With a favourable pharmacokinetic profile, ketamine is used in hospital and prehospital settings for emergency situations and is suitable for patients with many cardiac and respiratory conditions.

The effect of ketamine on preventing postpartum depression

Postpartum depression is a common disabling psychosocial disorder that could have adverse effects on the life of the mother, infant, and family. The present study was conducted to evaluate the effect of ketamine on preventing postpartum depression in women undergoing caesarian sections considering the relatively known positive effect of ketamine on major depression. The present double-blind, randomized clinical trial was conducted on 134 women undergoing scheduled caesarian sections. Participants were randomly allocated into two groups of control and intervention. To induce anesthesia, 1–2 mg/kg of body weight of Nesdonal and 0.5 mg/kg of body weight of ketamine were used in the intervention group, while only 3–5 mg/kg of body weight Nesdonal was administered in the control group. Data were gathered using the Edinburgh Postnatal Depression Scale (EPDS) in three stages: before the caesarian section and two and four weeks after the caesarian section. Data were analyzed using variance analysis with repeated measures and the Chi-square test. Results of the present study showed that the mean (± standard deviation) of the depression score in the intervention and control groups were 13.78±3.87 and 13.79±4.78(p = 0.98) before the caesarian section, 11.82±3.41 and 14.34±4.29 (p < 0.001) two weeks after and 10.84±3.48 and 13.09±3.79 (p = 0.001) four weeks after the caesarian section, respectively. Using ketamine in the induction of general anesthesia could be effective in preventing postpartum depression. However, further studies are required to strengthen these findings.

Guidelines for enhanced recovery after cardiac surgery. Consensus document of Spanish Societies of Anesthesia (SEDAR), Cardiovascular Surgery (SECCE) and Perfusionists (AEP)

The ERAS guidelines are intended to identify, disseminate and promote the implementation of the best, scientific evidence-based actions to decrease variability in clinical practice. The implementation of these practices in the global clinical process will promote better outcomes and the shortening of hospital and critical care unit stays, thereby resulting in a reduction in costs and in greater efficiency. After completing a systematic review at each of the points of the perioperative process in cardiac surgery, recommendations have been developed based on the best scientific evidence currently available with the consensus of the scientific societies involved.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

Serum BDNF levels and the antidepressant effects of electroconvulsive therapy with ketamine anaesthesia: a preliminary study

Objective

To firstly examine the relationship between serum brain-derived neurotrophic factor (BDNF) levels and antidepressant response to ketamine as an anaesthesia in electroconvulsive therapy (ECT) in Chinese patients with treatment-refractory depression (TRD).

Methods

Thirty patients with TRD were enrolled and underwent eight ECT sessions with ketamine anaesthesia (0.8 mg/kg) alone. Depression severity, response and remission were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD-17). Enzyme-linked immunosorbent assay (ELISA) was applied to examine serum BDNF levels in patients with TRD at baseline and after the second, fourth and eighth ECT sessions. Baseline serum samples were also collected for 30 healthy controls.

Results

No significant differences were observed in serum BDNF levels between patients with TRD and healthy controls at baseline (p > 0.05). The remission rate was 76.7% (23/30) after the last ECT treatment, although all patients with TRD obtained antidepressant response criteria. Serum BDNF levels were not altered compared to baseline, even between remitters and nonremitters (all p > 0.05), despite the significant reduction in HAMD-17 and Brief Psychiatric Rating Scale (BPRS) scores after ECT with ketamine anaesthesia (all p < 0.05). The antidepressant effects of ECT with ketamine anaesthesia were not correlated with changes in serum BDNF levels (all p > 0.05).

Conclusion

This preliminary study indicated that serum BDNF levels do not appear to be a reliable biomarker to determine the antidepressant effects of ketamine as an anaesthesia in ECT for patients with TRD. Further studies with larger sample sizes are warranted to confirm these findings.

INFLUENCE OF DIFFERENT TYPES OF ANESTHESIA FOR LAPAROSCOPIC HYSTERECTOMY ON THE DYNAMICS OF STRESS HORMONES

The aim of the study – to evaluate the influence of different variants of anesthesia, including low-opioid (LOA) and opioid-free anesthesia (OFA), on the dynamics of the stress response during laparoscopic hysterectomy. Materials and methods: 102 patients were randomly allocated into 3 groups: 37 women assigned to receive a standard opioid-based anesthesia (OBA group), 33 women – LOA group and 32 patients OFA group. Results: The patients of OFA group after induction and intubation of the trachea showed a significant (p<0.05) increase in cortisol level by 155.4 % and 160.9 % compared with the OBA group and LOA group. After completion of the hysterectomy, regardless of the variant of anesthesia, the level of cortisol exceeded the preoperative one (pOBA=0.116, pLOA=0.049, pOFA=0.043). Two hours after surgery with standard anesthesia (OBA group) there was a further increase in the concentration of cortisol in the blood, exceeding the initial values by 142.9 % (p=0.043). Patients in the LOA group and OFA group tended to decrease cortisolemia. The changes in adrenaline & glucose levels were somewhat similar. Conclusion: Use of OFA is accompanied by an aggravation of the stress response at the stage of hysterectomy, which is manifested by an increase in the level of adrenaline and cortisol. The most adequate perioperative protection is inherent in low-opioid anesthesia, which is accompanied by a lower release of stress hormones during hysterectomy and in the postoperative period. Opioid-based anesthesia provides adequate intraoperative protection, but is accompanied by insufficient postoperative analgesia.

Low-Dose Ketamine Infusion Versus Morphine Infusion During Abdominoplasty to Change the Postoperative Pain Profile

BACKGROUND

With the increased number of abdominoplasty all over the world, and the need to manage postoperative pain, it is a must to find proper and effective drugs to decrease opioid consumption in the postoperative period.

OBJECTIVES

In this double-blind randomized controlled clinical trial, we assumed that low-dose ketamine infusion will reduce the postoperative pain profile than the conventional method of morphine.

METHODS

The scheduled patients for abdominoplasty under general anesthesia were recruited in two groups: group (K) with low-dose ketamine infusion intra-operatively (80 patients) and group (M) with morphine infusion intra-operatively (80 patients). Both groups were monitored intraoperatively and postoperatively for rescue doses of fentanyl, visual analogue scale (VAS), and side effects.

RESULTS

There were no statistical differences between both groups regarding the fentanyl rescue doses intra- and postoperative with no remarkable side effects.

CONCLUSIONS

Low-dose ketamine has a useful analgesic effect in abdominoplasty similar to morphine without remarkable side effects, such as sedation or hallucinations.

Combination of Articaine and Ketamine V/S Articaine Alone After Surgical Extraction of Impacted Third Molars

Objective:

Local anesthetics are the most effective drugs available for the management of pain while performing operative procedures. This study was performed to compare the clinical efficacy of treatment with local anesthetic articaine (4%) with ketamine and local anesthetic articaine alone (4%) for the relief or prevention of postoperative pain, swelling, and trismus after the surgical extraction of impacted mesioangular third molars.

Materials and Methods:

Sixty patients undergoing the extraction of impacted mesioangular mandibular third molars were included in the study. The patients were randomly divided into two groups: local anesthetic alone (LAA) and local anesthetic plus ketamine (LAK).

Results:

Facial swelling following surgery on postoperative days was significantly lower in the LAK group than in the LAA group on 3^rd and 7^th postoperative days (P < 0.05). Mouth opening on the postoperative days was significantly greater in the LAK group than in the LAA group on 3^rd and 7^th postoperative days (P < 0.05). The pain scores on the visual analog scale at 30 min and 1 h, 4 h, 12 h, and 24 h after the surgery were significantly higher in the LAA group than in the LAK group and there was no significant difference in heart rate, oxygen saturation, and blood pressure in both the groups.

Conclusion:

In this present study, the effect of articaine with ketamine in comparison with articaine alone intraoperatively and postoperatively was observed, and it revealed that the combination of articaine with ketamine produced good local anesthesia and provide good postoperative analgesia with less swelling and significantly less trismus.

The Anesthesiologist's Armamentarium: From Recreation to Medication and Back

For millennia, mankind has sought a means of altering consciousness, often aided by naturally occurring elements. Psychotropic substances have been an integral part of spiritual, medicinal, and recreational aspects of life. The origin of anesthesiology stems directly from the use of recreational drugs; early inhaled anesthetics were first used as a means of entertainment. Hence, it is no surprise that many medications in the anesthesiologist's armamentarium are diverted for recreational use. In the 172 years following the first successful public demonstration of ether anesthesia, many drugs with abuse potential have been introduced to the practice of anesthesia. Although anesthesiologists are aware of the abuse potential of these drugs, how these drugs are obtained and used for recreational purposes is worthy of discussion. There are articles describing the historical and recreational use of specific drug classes. However, to the best of our knowledge, this is the first comprehensive review focusing on the breadth of drugs used by anesthesiologists.

Adjunct low-dose ketamine infusion vs standard of care in mechanically ventilated critically ill patients at a Tertiary Saudi Hospital (ATTAINMENT Trial): study protocol for a randomized, prospective, pilot, feasibility trial

Background

A noticeable interest in ketamine infusion for sedation management has developed among critical care physicians for critically ill patients. The 2018 Pain, Agitation/sedation, Delirium, Immobility, and Sleep disruption guideline suggested low-dose ketamine infusion as an adjunct to opioid therapy to reduce opioid requirements in post-surgical patients in the intensive care unit (ICU). This was, however, rated as conditional due to the very low quality of evidence. Ketamine has favorable characteristics, making it an especially viable alternative for patients with respiratory and hemodynamic instability. The Analgo-sedative adjuncT keTAmine Infusion iN Mechanically vENTilated ICU patients (ATTAINMENT) trial aims to assess the effect and safety of adjunct low-dose continuous infusion of ketamine as an analgo-sedative compared to standard of care in critically ill patients on mechanical ventilation (MV) for ≥ 24 h.

Methods/design

This trial is a prospective, randomized, active controlled, open-label, pilot, feasibility study of adult ICU patients (> 14 years old) on MV. The study will take place in the adult ICUs in the King Faisal Specialist Hospital and Research Center (KFSH&RC), Riyadh, Saudi Arabia, and will enroll 80 patients. Patients will be randomized post-intubation into two groups: the intervention group will receive an adjunct low-dose continuous infusion of ketamine plus standard of care. Ketamine will be administered over a period of 48 h at a fixed infusion rate of 2 μg/kg/min (0.12 mg/kg/h) in the first 24 h followed by 1 μg/kg/min (0.06 mg/kg/h) in the second 24 h. The control group will receive standard of care in the ICU (propofol and/or fentanyl and/or midazolam) according to the KFSH&RC sedation and analgesia protocol as clinically appropriate. The primary outcome is MV duration until ICU discharge, death, extubation, or 28 days post-randomization, whichever comes first.

Discussion

The first patient was enrolled on 1 September 2019. As of 10 October 2019, a total of 16 patients had been enrolled. We expect to complete the recruitment by 31 December 2020. The findings of this pilot trial will likely justify further investigation for the role of adjunct low-dose ketamine infusion as an analgo-sedative agent in a larger, multicenter, randomized controlled trial.

Trial registration

ClinicalTrials.gov: NCT04075006. Registered on 30 August 2019. Current controlled trials: ISRCTN14730035. Registered on 3 February 2020.

Association between intravenous ketamine-induced stress hormone levels and long-term fear memory renewal in Sprague-Dawley rats

Ketamine is a multimodal dissociative anesthetic and analgesic that is widely used after traumatic injury. We previously reported that an analgesic dose of intravenous (IV) ketamine infusion (10 mg/kg, 2-h) after fear conditioning enhanced short-term fear memory in rats. Here, we investigated the effects of the same dose of an IV ketamine infusion on plasma stress hormone levels and long-term fear memory in rats. Adult male Sprague-Dawley rats (9-week-old with an average weight of 308 g upon arrival) received a ketamine infusion (0 or 10 mg/kg, 2-h) immediately after auditory fear conditioning (three auditory tone and footshock [0.6 mA, 1-s] pairings) on Day 0. After the infusion, a blood sample was collected from a jugular vein catheter for corticosterone and progesterone assays, and each animal was tested on tail flick to measure thermal antinociception. One week later, animals were tested on fear extinction acquisition (Day 7), fear extinction retrieval (Day 8), and fear renewal (Day 9). The IV ketamine infusion, compared to the saline infusion, reduced locomotor activity (sedation), increased tail flick latency (antinociception), and elevated plasma corticosterone and progesterone levels. The ketamine infusion did not alter long-term fear memory extinction or fear renewal. However, elevated corticosterone and progesterone levels resulting from the ketamine infusion were correlated with sedation, antinociception, and long-term fear memory renewal. These results suggest that individual differences in sensitivity to acute ketamine may predict vulnerability to develop fear-related disorders.

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.

Does Sub-Anesthetic Ketamine Provide Postoperative Analgesia for Third Molar Surgery?

PURPOSE

Despite ketamine's effectiveness as an anesthetic and its known analgesic properties, the role of ketamine in postoperative pain after third molar surgery remains unclear. Therefore, this study aimed to investigate whether patients undergoing third molar surgery who received a sub-anesthetic preoperative dose of intravenous ketamine would experience less postoperative pain.

MATERIALS AND METHODS

We implemented a randomized, double-blinded, placebo-controlled trial. The study sample consisted of participants undergoing third molar surgery with procedural sedation anesthesia. Participants were randomized to receive a preoperative intravenous dose of ketamine or placebo, as predictor variables. The primary outcome variable was postoperative pain intensity determined by a 10-point visual analog scale at 6-hour intervals over a period of 48 hours. The secondary outcome variable was the quantity of postoperative non-opioid and opioid consumption. Other variables included the extent and difficulty of surgery performed, patient satisfaction, gender, and age. Data analysis involved descriptive statistics, multivariate analysis, and regression analysis. The P value was set at .05.

RESULTS

A total of 134 participants were randomly enrolled into either the ketamine group (n = 74, 55.2%) or placebo group (n = 60, 44.8%). No statistically significant differences in the distribution of study variables were found between the groups. A small yet statistically significant (P < .05) difference was noted in the median pain score at 6 hours postoperatively, with the ketamine group experiencing more pain. However, no further differences were detected at any postoperative time between the 2 groups. Similar results were obtained after adjusting for age, gender, and surgical difficulty. No difference in the amount of postoperative non-opioid or opioid medication use was found between the 2 groups.

CONCLUSIONS

This study did not find evidence that a preoperative sub-anesthetic dose of ketamine could reduce pain after third molar surgery or have any effects on non-opioid or opioid analgesic consumption. Nevertheless, ketamine remains a valuable option among sedation medications for oral and maxillofacial surgeons.

Persistent pain after cesarean delivery

The incidence of persistent pain after cesarean deliveries (CD) varies but is much lower than after comparable surgeries. However, with over four million deliveries annually and a rising CD rate, even a low prevalence of persistent pain after CD impacts many otherwise healthy young women. Consideration of the pathophysiology of persistent pain after surgery and the risk factors predisposing women to persistent and chronic pain after CD provides insights into the prevention and treatment of persistent pain; and improves the quality of care and recovery after CD. The findings that the peripartum state and oxytocin confer protection against persistent pain may provide new and interesting perspectives for the prevention and treatment of chronic pain caused by trauma or surgery. Predictive tools available to identify and target patients at high risk of acute and chronic pain have mostly weak to modest predictive correlations and many are either not clinically feasible or too time-consuming to apply. Persistent pain has been linked to the severity of acute postoperative pain and opioid exposure. Modified surgical techniques, neuraxial anesthesia and opioid-sparing analgesia may help limit the development of persistent and chronic pain. The goal of this narrative review is to examine the incidence of persistent pain after CD; review briefly the underlying pathophysiology of persistent pain and the transition from acute to chronic pain (with particular emphasis on the uniqueness after CD); and to review modifiable risk factors and prevention strategies that identify at-risk patients and allow tailored treatment.

Effects of subanesthetic intravenous ketamine infusion on neuroplasticity-related proteins in the prefrontal cortex, amygdala, and hippocampus of Sprague-Dawley rats

Ketamine, a multimodal dissociative anesthetic, is a powerful analgesic administered following trauma due to its hemodynamic and respiratory stability. However, ketamine can cause hallucination and dissociation which may adversely impact traumatic memory after an injury. The effects of ketamine on proteins implicated in neural plasticity are unclear due to different doses, routes, and timing of drug administration in previous studies. Here, we investigated the effects of a single intravenous (IV) ketamine infusion on protein levels in three brain regions of rats. Adult male Sprague-Dawley rats with indwelling IV catheters underwent an auditory fear conditioning (three pairings of tone and mild footshock 0.8 mA, 0.5 s) and received a high dose of IV ketamine (0 or 40 mg/kg/2 h) infusion (Experiment 1). In a follow-up study, animals received a low dose of IV ketamine (0 or 10 mg/kg/2 h) infusion (Experiment 2). Two hours after the infusion, brain tissue from the medial prefrontal cortex (mPFC), hippocampus, and amygdala were collected for western blot analyses. Protein levels of a transcription factor (c-Fos), brain-derived neurotrophic factor (BDNF), and phosphorylated extracellular signal-regulated kinase (pERK) were quantified in these regions. The 40 mg/kg ketamine infusion increased c-Fos levels in the mPFC and amygdala as well as pERK levels in the mPFC and hippocampus. The 10 mg/kg ketamine infusion increased BDNF levels in the amygdala, but decreased pERK levels in the mPFC and hippocampus. These findings suggest that a clinically relevant route of ketamine administration produces dose-dependent and brain region-specific effects on proteins involved in neuroplasticity.

The efficacy of different modes of analgesia in postoperative pain management and early mobilization in postoperative cardiac surgical patients: A systematic review

Cardiac surgery induces severe postoperative pain and impairment of pulmonary function, increases the length of stay (LOS) in hospital, and increases mortality and morbidity; therefore, evaluation of the evidence is needed to assess the comparative benefits of different techniques of pain management, to guide clinical practice, and to identify areas of further research. A systematic search of the Cochrane Central Register of Controlled Trials, DARE database, Joanna Briggs Institute, Google scholar, PUBMED, MEDLINE, EMBASE, Academic OneFile, SCOPUS, and Academic search premier was conducted retrieving 1875 articles. This was for pain management postcardiac surgery in intensive care. Four hundred and seventy-one article titles and 266 abstracts screened, 52 full text articles retrieved for critical appraisal, and ten studies were included including 511 patients. Postoperative pain (patient reported), complications, and LOS in intensive care and the hospital were evaluated. Anesthetic infiltrations and intercostal or parasternal blocks are recommended the immediate postoperative period (4-6 h), and patient-controlled analgesia (PCA) and local subcutaneous anesthetic infusions are recommended immediate postoperative and 24-72 h postcardiac surgery. However, the use of mixed techniques, that is, PCA with opioids and local anesthetic subcutaneous infusions might be the way to go in pain management postcardiac surgery to avoid oversedation and severe nausea and vomiting from the narcotics. Adequate studies in the use of ketamine for pain management postcardiac surgery need to be done and it should be used cautiously.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

Enhanced fear memories and brain glucose metabolism (18F-FDG-PET) following sub-anesthetic intravenous ketamine infusion in Sprague-Dawley rats

Ketamine is a multimodal dissociative anesthetic, which provides powerful analgesia for victims with traumatic injury. However, the impact of ketamine administration in the peri-trauma period on the development of post-traumatic stress disorder (PTSD) remains controversial. Moreover, there is a major gap between preclinical and clinical studies because they utilize different doses and routes of ketamine administration. Here, we investigated the effects of sub-anesthetic doses of intravenous (IV) ketamine infusion on fear memory and brain glucose metabolism (BGluM) in rats. Male Sprague-Dawley rats received an IV ketamine infusion (0, 2, 10, and 20 mg/kg, 2 h) or an intraperitoneal (IP) injection (0 and 10 mg/kg) following an auditory fear conditioning (3 pairings of tone and foot shock [0.6 mA, 1 s]) on day 0. Fear memory retrieval, fear extinction, and fear recall were tested on days 2, 3, and 4, respectively. The effects of IV ketamine infusion (0 and 10 mg/kg) on BGluM were measured using ¹⁸F-fluoro-deoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT). The IV ketamine infusion dose-dependently enhanced fear memory retrieval, delayed fear extinction, and increased fear recall in rats. The IV ketamine (10 mg/kg) increased BGluM in the hippocampus, amygdala, and hypothalamus, while decreasing it in the cerebellum. On the contrary, a single ketamine injection (10 mg/kg, IP) after fear conditioning facilitated fear memory extinction in rats. The current findings suggest that ketamine may produce differential effects on fear memory depending on the route and duration of ketamine administration.