'Balanced analgesia' in the perioperative period: is there a place for ketamine?

The Role of Intravenous Anesthetics for Neuro: Protection or Toxicity?

The primary intravenous anesthetics employed in clinical practice encompass dexmedetomidine (Dex), propofol, ketamine, etomidate, midazolam, and remimazolam. Apart from their established sedative, analgesic, and anxiolytic properties, an increasing body of research has uncovered neuroprotective effects of intravenous anesthetics in various animal and cellular models, as well as in clinical studies. However, there also exists conflicting evidence pointing to the potential neurotoxic effects of these intravenous anesthetics. The role of intravenous anesthetics for neuro on both sides of protection or toxicity has been rarely summarized. Considering the mentioned above, this work aims to offer a comprehensive understanding of the underlying mechanisms involved both in the central nerve system (CNS) and the peripheral nerve system (PNS) and provide valuable insights into the potential safety and risk associated with the clinical use of intravenous anesthetics.

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.

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.

Pupillary monitoring decreases remifentanil consumption during laparoscopic uterine surgery and improves postoperative recovery

BACKGROUND

The aim of this paper was to explore pupillary monitoring for determining remifentanil consumption during general anesthesia and evaluating postoperative recovery quality.

METHODS

Eighty patients undergoing elective laparoscopic uterine surgery were randomly divided into pupillary monitoring group (Group P) and control group (Group C). In Group P, remifentanil dosage during general anesthesia was determined according to pupil dilation reflex; in Group C, it was adjusted according to hemodynamic changes. Intraoperative remifentanil consumption and endotracheal tube extraction time were recorded. The Numerical Rating Scale (NRS) Score, hemodynamic changes, and opioid-related adverse reactions in the post-anesthesia care unit were also recorded. The parameters of pupil light reflex from extubation to 30 min after extubation were analyzed in Group P, and the responsiveness of these parameters and hemodynamic changes to NRS was determined by ROC curve analyses.

RESULTS

Compared with Group C, in Group P, intraoperative remifentanil consumption, the NRS Score at 20 minutes after extubation, extubation time, and the incidence of nausea, vomiting, and respiratory amnesia were all significantly decreased (all, P<0.05). In Group P, ∆HR and ∆MAP had no value in judging the change of NRS. The ROC values and diagnostic cutoff values of ΔInit, ΔACV, and ΔMCV responding to NRS variation were 0.775 (95% CI: 0.582-0.968), 0.734(95% CI: 0.537-0.930), and 0.822 (95% CI: 0.648-0.997) and 0.21 (sensitivity, 92.3%; specificity, 23.1%), -1.3 (sensitivity, 92.3%; specificity, 18.3%), and -1.0 (sensitivity, 84.6%; specificity, 17.7%), respectively.

CONCLUSIONS

Intraoperative pupil dilation reflex monitoring can reduce remifentanil consumption and improve postoperative recovery quality. Furthermore, postoperative pupil light reflex monitoring can help evaluate pain degree with high sensitivity.

Intraoperative intravenous low-dose esketamine improves quality of early recovery after laparoscopic radical resection of colorectal cancer: A prospective, randomized controlled trial

BACKGROUND

Esketamine has higher potency, stronger receptor affinity, a stronger analgesic effect, a higher in vivo clearance rate, and a lower incidence of adverse reactions when compared to ketamine. However, there have been few ketamine studies to assess patient-centered, overall recovery outcomes from the perspective of patients with colorectal cancer.

METHODS

This was a prospective, randomized controlled trial. Ninety-two patients undergoing laparoscopic radical resection of colorectal cancer were randomly assigned to either the esketamine (K group) or non-eskatamine (C group) group. After anesthesia induction, a loading dose of 0.25 mg/kg was administered, followed by continuous infusion at a rate of 0.12 mg.kg-1.h-1 until closure of surgical incisions in the K group. In the C group, an equivalent volume of normal saline was infused. The primary outcome was quality of recovery at 24 h after surgery, as measured by the Quality of Recovery-15 (QoR-15) scale. The QoR-15 was evaluated at three timepoints: before (Tbefore), 24 h (T24h) and 72 h (T72h) after surgery.

MAIN RESULTS

A total of 88 patients completed this study. The total QoR-15 scores in K group (n = 45) were higher than in the C group (n = 43) at 24 h: 112.33 ± 8.79 vs. 103.93 ± 9.03 (P = 0.000) and at 72 h: 118.73 ± 7.82 vs. 114.79 ± 7.98 (P = 0.022). However, the differences between the two groups only had clinical significance at 24 h after surgery. Among the five dimensions of the QoR-15, physical comfort (P = 0.003), emotional state (P = 0.000), and physical independence (P = 0.000) were significantly higher at 24 h in the K group, and physical comfort (P = 0.048) was higher at 72 h in the K group.

CONCLUSIONS

This study found that intraoperative intravenous low-dose esketamine could improve the early postoperative quality of recovery in patients undergoing laparoscopic radical resection of colorectal cancer from the perspective of patients.

A prospective observational study of the efficacy of ketamine for rescue analgesia in the postanesthesia recovery unit

BACKGROUND

Early severe postoperative pain is frequently resistant to management with opioid analgesia alone. Perioperative low-dose ketamine as an analgesia adjunct has been studied extensively. Its efficacy as a rescue analgesic in the postanesthesia care unit (PACU) has not been determined. The objective of this study was to evaluate the analgesic efficacy of low-dose bolus ketamine for opioid-resistant pain in the PACU by measuring its effect on numerical rating scale (NRS) pain scores and opioid requirement.

METHODS

This was a prospective observational study of adult noncardiac surgery patients with significant postoperative pain in the PACU. Patients were administered bolus doses of intravenous ketamine in 10-mg increments, repeated two to three times to an approximate maximum dose of 0.25 mg·kg-1. Primary outcomes were resting pain score reduction and opioid use from time of bolus ketamine administration to 30 min after administration of final ketamine bolus. The secondary outcome was incidence of side effects from ketamine administration.

RESULTS

A convenience sample of 100 patients was chosen. The mean (standard deviation) NRS resting pain score reduction 30 min after iv ketamine administration was 2.7 (1.8) (P < 0.001). Patients with a history of previous opioid use or chronic pain were not more responsive to the effects of low-dose bolus ketamine. There were no ketamine-related adverse effects in any of the study patients.

CONCLUSION

Administration of low-dose bolus ketamine in the PACU for severe opioid-resistant pain was associated with a significant improvement in analgesia in this observational study.

Phenotype- and species-specific skin proteomic signatures for incision-induced pain in humans and mice

BACKGROUND

Acute pain after surgery is common and often leads to chronic post-surgical pain, but neither treatment nor prevention is currently sufficient. We hypothesised that specific protein networks (protein-protein interactions) are relevant for pain after surgery in humans and mice.

METHODS

Standardised surgical incisions were performed in male human volunteers and male mice. Quantitative and qualitative sensory phenotyping were combined with unbiased quantitative mass spectrometry-based proteomics and protein network theory. The primary outcomes were skin protein signature changes in humans and phenotype-specific protein-protein interaction analysis 24 h after incision. Secondary outcomes were interspecies comparison of protein regulation as well as protein-protein interactions after incision and validation of selected proteins in human skin by immunofluorescence.

RESULTS

Skin biopsies in 21 human volunteers revealed 119/1569 regulated proteins 24 h after incision. Protein-protein interaction analysis delineated remarkable differences between subjects with small (low responders, n=12) and large incision-related hyperalgesic areas (high responders, n=7), a phenotype most predictive of developing chronic post-surgical pain. Whereas low responders predominantly showed an anti-inflammatory protein signature, high responders exhibited signatures associated with a distinct proteolytic environment and persistent inflammation. Compared to humans, skin biopsies in mice habored even more regulated proteins (435/1871) 24 h after incision with limited overlap between species as assessed by proteome dynamics and PPI. Immunohistochemistry confirmed the expression of high priority candidates in human skin biopsies.

CONCLUSIONS

Proteome profiling of human skin after incision revealed protein-protein interactions correlated with pain and hyperalgesia, which may be of potential significance for preventing chronic post-surgical pain. Importantly, protein-protein interactions were differentially modulated in mice compared to humans opening new avenues for successful translational research.

Risk factors for chronic postsurgical pain in visceral surgery: a matched case–control analysis

Purpose

Chronic postsurgical pain (CPSP) after abdominal visceral surgery is an underestimated long-term complication with relevant impact on health-related quality of life and socioeconomic costs. Early identification of affected patients is important. We aim to identify the incidence and risk factors for CPSP in this patient population.

Methods

Retrospective case–control matched analysis including all patients diagnosed with CPSP after visceral surgery in our institution between 2016 and 2019. One-to-two case–control matching was based on operation category (HPB, upper-GI, colorectal, transplantation, bariatric, hernia and others) and date of surgery. Potential risk factors for CPSP were identified using conditional multivariate logistic regression.

Results

Among a cohort of 3730 patients, 176 (4.7%) were diagnosed with CPSP during the study period and matched to a sample of 352 control patients. Independent risk factors for CPSP were age under 55 years (OR 2.64, CI 1.51–4.61), preexisting chronic pain of any origin (OR 3.42, CI 1.75–6.67), previous abdominal surgery (OR 1.99, CI 1.11–3.57), acute postoperative pain (OR 1.29, CI 1.16–1.44), postoperative use of non-steroidal anti-inflammatory drugs (OR 3.73, OR 1.61–8.65), opioid use on discharge (OR 3.78, CI 2.10–6.80) and length of stay over 3 days (OR 2.60, CI 1.22–5.53). Preoperative Pregabalin intake was protective (OR 0.02, CI 0.002–0.21).

Conclusion

The incidence of CPSP is high and associated with specific risk factors, some of them modifiable. Special attention should be given to sufficient treatment of preexisting chronic pain and acute postoperative pain.

Opioid Sparing Analgesics in Spine Surgery

Combinations of various nonopioid analgesics have been used to decrease pain and opioid consumption postoperatively allowing for faster recovery, improved patient satisfaction, and decreased morbidity. These opioid alternatives include acetaminophen, NSAIDs, COX-2 specific inhibitors, gabapentinoids, local anesthetics, dexamethasone, and ketamine. Each of these drugs presents its own advantages and disadvantages which can make it difficult to implement universally. In addition, ambiguous administration guidelines for these nonopioid analgesics lead to a difficult implementation of standardization protocols in spine surgery. A focus on the efficacy of different pain modalities specifically within spine surgery was implemented to assist with this standardized protocol endeavor and to educate surgeons on limiting opioid prescribing in the postoperative period. The purpose of this review article is to investigate the various opioid sparing medications that have been used to decrease morbidity in spine surgery and better assist surgeons in managing postoperative pain. Methods. A narrative review of published literature was conducted using the search function in Google scholar and PubMed was used to narrow down search criteria. The keywords “analgesics,” “spine,” and “pain” were used.

Exploratory clinical trial to evaluate the efficacy and safety of carbon dioxide paste in healthy people

INTRODUCTION

Scarring and pain are postoperative complications in patients after head and neck cancer treatment; however, there is no effective treatment. These complications are affected by local blood flow disorders, and it is well known that the transcutaneous application of carbon dioxide (CO2) improves local blood flow. Previously, we have shown that the transcutaneous application of carbon dioxide causes absorption of CO2 and increase the oxygen (O2) pressure in the treated tissue; it is expected that the application of CO2 may reduce scarring and pain caused by cancer treatment. We newly introduced the CO2 paste as a new CO2 application method, which does not need to use CO2 gas directly. In this study, we aimed to apply of CO2 paste to healthy people and to investigate its usefulness, safety and feasibility by analysing the increase in blood flow and frequency of adverse events.

METHODS

We applied carbon dioxide paste to skin over the sternocleidomastoid and gastrocnemius muscles of eight healthy volunteers. The changes in blood flow before and after the CO2 paste application using dynamic MRI, and changes in the vital signs were evaluated.

RESULTS

In the neck area and middle layer of the lower leg, the signal intensity (SI) significantly increased 60 seconds after application. In the surface layer of the lower leg, the SI was significantly increased 60 and 300 seconds after paste application. Although mild heat was noted after the paste application, no obvious adverse events occurred.

CONCLUSION

We demonstrated the increase in SI by dynamic MRI at the site of the carbon dioxide paste application, which indicates the paste application is effective in improving the blood flow.

Towards better predictive models of chronic post-surgical pain: fitting to the dynamic nature of the pain itself

Chronic post-surgical pain predictive scores exist, but none has yet demonstrated an impact on patient care. Van Driel and colleagues offer an additional perspective on early postoperative detection of patient at risk of chronic post-surgical pain to enable early interventions in prevention and treatment. The authors derived and validated a model based on four easily obtainable predictors that could help clinicians assess and treat patients at risk. Additional work is needed to prove reliability and clinical benefit of chronic post-surgical pain prediction and intervention.

Diagnosis, Treatment, and Management of Painful Scar: A Narrative Review

Painful scars can develop after surgery or trauma, with symptoms ranging from a minor itch to intractable allodynia. The problem of the painful scar may involve both intraneural and extraneural structures, requiring a systematic approach to diagnosis and treatment of this neuropathic pain condition that can impact quality of life and function profoundly. In this review, we outline the algorithm for the diagnosis, management, medical and surgical treatment of painful scars.

Opioid-Sparing Analgesia Impacts the Perioperative Anesthetic Management in Major Abdominal Surgery

Background and Objectives: The management of acute postoperative pain (APP) following major abdominal surgery implies various analgetic strategies. Opioids lie at the core of every analgesia protocol, despite their side effect profile. To limit patients’ exposure to opioids, considerable effort has been made to define new opioid-sparing anesthesia techniques relying on multimodal analgesia. Our study aims to investigate the role of adjuvant multimodal analgesic agents, such as ketamine, lidocaine, and epidural analgesia in perioperative pain control, the incidence of postoperative cognitive dysfunction (POCD), and the incidence of postoperative nausea and vomiting (PONV) after major abdominal surgery. Materials and Methods: This is a clinical, observational, randomized, monocentric study, in which 80 patients were enrolled and divided into three groups: Standard group, C (n = 32), where patients received perioperative opioids combined with a fixed regimen of metamizole/acetaminophen for pain control; co-analgetic group, Co-A (n = 26), where, in addition to standard therapy, patients received perioperative systemic ketamine and lidocaine; and the epidural group, EA (n = 22), which included patients that received standard perioperative analgetic therapy combined with epidural analgesia. We considered the primary outcome, the postoperative pain intensity, assessed by the visual analogue scale (VAS) at 1 h, 6 h, and 12 h postoperatively. The secondary outcomes were the total intraoperative fentanyl dose, total postoperative morphine dose, maximal intraoperative sevoflurane concentration, confusion assessment method for intensive care units score (CAM-ICU) at 1 h, 6 h, and 12 h postoperatively, and the postoperative dose of ondansetron as a marker for postoperative nausea and vomiting (PONV) severity. Results: We observed a significant decrease in VAS score, as the primary outcome, for both multimodal analgesic regimens, as compared to the control. Moreover, the intraoperative fentanyl and postoperative morphine doses were, consequently, reduced. The maximal sevoflurane concentration and POCD were reduced by EA. No differences were observed between groups concerning PONV severity. Conclusions: Multimodal analgesia concepts should be individualized based on the patient’s needs and consent. Efforts should be made to develop strategies that can aid in the reduction of opioid use in a perioperative setting and improve the standard of care.

The effect of low-dose ketamine on postoperative quality of recovery in patients undergoing breast cancer surgery: A randomised, placebo-controlled trial

BACKGROUND

Low-dose ketamine has been proved to reduce opioid consumption, prevent depressant action and improve postoperative analgesia. Women undergoing mastectomy experience may not only have persistent postoperative pain syndromes but also emotional problems. However, the effect of intraoperative infusion of low-dose ketamine on postoperative quality of recovery among these patients has not yet been fully studied.

METHODS

In this prospective, randomised, single-centre trial, 100 patients planned for modified radical mastectomy were randomly assigned to one of two groups: control group (group C) or ketamine group (group K) at a ratio of 1:1. Group K received the bolus dose of 0.5 mg/kg ketamine and followed by 0.25 mg·kg^-1 ·h^-1 after the compliment of anaesthesia induction until the end of the surgery, whilst group C received an equivalent dose and regiment of normal saline was group K. The primary outcome was to assess the effects of low-dose ketamine on postoperative quality of recovery using the 40-Item Quality of Recovery (QoR-40) scale on a postoperative day 1 (POD1). The secondary outcome was to assess the numeric rating scale (NRS) at 4, 24 and 48 h after the operation, identity-consequence fatigue scale (ICFS) scores at 3 and 7 days after the operation, hospital anxiety and depression scale (HADS) scores at 2 days and 3 months, as well as chronic pain at 3 months. In a post hoc analysis, the 5 subsections of the QoR-40 scores were also analysed.

RESULTS

A total of 100 subjects were randomised. The primary outcome of QoR-40 scores on POD1 was available in 97 patients (49 in group C and 48 in group K). Global QoR-40 scores were not significantly different between group C and group K (169.8 ± 10.7 vs. 172.7 ± 7.5, 95% CI -1.35 (-5.50, 2.80), p = .519). In a post hoc analysis, pain scores were significantly higher in group K than in group C (29.8 ± 3.8 vs. 31.7 ± 2.1, 95% CI -1.81 (-3.00, -0.62), p = .003). The secondary outcomes, including NRS, ICFS scores, HADS scores and chronic pain had no difference between groups (p value for each >.15).

CONCLUSION

Intraoperative low-dose ketamine infusion did not improve the overall quality of recovery on POD 1 in patients undergoing breast cancer surgery.

Evaluation of antihyperalgesic and analgesic effects of 35% nitrous oxide when combined with remifentanil: A randomised phase 1 trial in volunteers

BACKGROUND

Remifentanil is an effective drug in peri-operative pain therapy, but it can also induce and aggravate hyperalgesia. Supplemental administration of N2O may help to reduce remifentanil-induced hyperalgesia.

OBJECTIVE

To evaluate the effect of 35 and 50% N2O on hyperalgesia and pain after remifentanil infusion.

DESIGN

Single site, phase 1, double-blind, placebo-controlled, randomised crossover study.

SETTING

University Hospital, Germany from January 2012 to April 2012.

PARTICIPANTS

Twenty-one healthy male volunteers.

INTERVENTIONS

Transcutaneous electrical stimulation induced spontaneous acute pain and stable areas of hyperalgesia. Each volunteer underwent the following four sessions in a randomised order: 50 to 50% N2-O2 and intravenous (i.v.) 0.9% saline infusion (placebo); 50 to 50% N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (remifentanil); 35 to 15 to 50% N2O-N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (tested drug) and 50 to 50% N2O-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (gas active control). Gas mixtures were inhaled for 60 min; i.v. drugs were administered for 30 min.

MAIN OUTCOME MEASURES

Areas of pin-prick hyperalgesia, areas of touch-evoked allodynia and pain intensity on a visual analogue scale were assessed repeatedly for 160 min.

RESULTS

Data from 20 volunteers were analysed. There were significant treatment and treatment-by-time effects regarding areas of hyperalgesia (P < 0.001). After the treatment period, the area of hyperalgesia was significantly reduced (P < 0.001) in the tested drug and in the gas active control (30.6 ± 9.25 and 24.4 ± 7.3 cm2, respectively) compared with remifentanil (51.0 ± 17.0 cm2). There was also a significant difference between the gas active control and the tested drug sessions (P < 0.001). For the area of allodynia and pain rating, results were consistent with the results for hyperalgesia.

CONCLUSIONS

Administration of 35% N2O significantly reduced hyperalgesia, allodynia and pain intensity induced after remifentanil. It might therefore be suitable in peri-operative pain relief characterised by hyperalgesia and allodynia, such as postoperative pain, and may help to reduce opioid demand.

TRIAL REGISTRATION

EudraCT-No.: 2011-000966-37.

Effects of Esketamine on Acute and Chronic Pain After Thoracoscopy Pulmonary Surgery Under General Anesthesia: A Multicenter-Prospective, Randomized, Double-Blind, and Controlled Trial

Background: Post-operative pain management for patients undergoing thoracoscopy surgery is challenging for clinicians which increase both health and economic burden. The non-selective NMDA receptor antagonist esketamine possesses an analgesic effect twice that of ketamine. The application of esketamine might be beneficial in alleviating acute and chronic pain after thoracic surgery. The current study describes the protocol aiming to evaluate the analgesic effect of esketamine after pulmonary surgery via visual analog scale (VAS) score for acute and chronic pain.

Methods: A multi-center, prospective, randomized, controlled, double-blind study is designed to explore the analgesic effect of esketamine in randomized patients undergoing video-assisted thoracoscopic surgery (VATS) with general anesthesia. Patients will be randomly assigned to Esketamine Group (Group K) and Control Group (Group C) in a ratio of 1:1. Group K patients will receive esketamine with a bolus of 0.1 mg/kg after anesthesia induction, 0.1 mg/kg/h throughout the operation and 0.015 mg/kg/h in PCIA after surgery while Group C patients will receive the same volume of normal saline. The primary outcome is to measure the pain intensity through the VAS score at 3 months after the operation. The secondary outcome includes VAS score at 1, 4, 8, 24, and 48 h and on the 7th day and 1 month after the operation, complications, ketamine-related neurological side effects, recovery time of bowel function, and total amount of supplemental analgesics.

Discussion: The results of the current study might illustrate the analgesic effect of esketamine for patients undergoing thoracoscopy pulmonary surgery and provide evidence and insight for perioperative pain management.

Study Registration: The trial was registered with Chinese Clinical Trial Registry (CHICTR) on Nov 18th, 2020 (ChiCTR2000040012).

Impact of Ketamine on Opioid Use and Persistent Pain After Cytoreductive Surgery with Hyperthermic Chemotherapy

Background

Persistent pain and opioid use can be devastating after cytoreductive surgery (CRS) and hyperthermic intraoperative chemotherapy (HIPEC).

Methods

We conducted a retrospective study to investigate the impact of ketamine use on postoperative complications and persistent and chronic pain after CRS-HIPEC.

Results

Ketamine reduced perioperative opioid use before and after implementation of recovery after surgery programs. Ketamine did not impact the formation of persistent and chronic pain formation and long-term opioid use. Postoperative complications and postoperative re-operations were independent predictors of persistent pain. Interestingly, the risk of having a complication was increased by 1% for every doubling in opioids used intraoperatively.

Conclusion

Ketamine use reduces perioperative opioid consumption in patients undergoing CRS-HIPEC, but it is not associated with improvements in long-term opioid use and chronic pain.

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.

Pharmacotherapy for the Prevention of Chronic Pain after Surgery in Adults: An Updated Systematic Review and Meta-analysis

BACKGROUND

Chronic postsurgical pain can severely impair patient health and quality of life. This systematic review update evaluated the effectiveness of systemic drugs to prevent chronic postsurgical pain.

METHODS

The authors included double-blind, placebo-controlled, randomized controlled trials including adults that evaluated perioperative systemic drugs. Studies that evaluated same drug(s) administered similarly were pooled. The primary outcome was the proportion reporting any pain at 3 or more months postsurgery.

RESULTS

The authors identified 70 new studies and 40 from 2013. Most evaluated ketamine, pregabalin, gabapentin, IV lidocaine, nonsteroidal anti-inflammatory drugs, and corticosteroids. Some meta-analyses showed statistically significant-but of unclear clinical relevance-reductions in chronic postsurgical pain prevalence after treatment with pregabalin, IV lidocaine, and nonsteroidal anti-inflammatory drugs. Meta-analyses with more than three studies and more than 500 participants showed no effect of ketamine on prevalence of any pain at 6 months when administered for 24 h or less (risk ratio, 0.62 [95% CI, 0.36 to 1.07]; prevalence, 0 to 88% ketamine; 0 to 94% placebo) or more than 24 h (risk ratio, 0.91 [95% CI, 0.74 to 1.12]; 6 to 71% ketamine; 5 to 78% placebo), no effect of pregabalin on prevalence of any pain at 3 months (risk ratio, 0.88 [95% CI, 0.70 to 1.10]; 4 to 88% pregabalin; 3 to 80% placebo) or 6 months (risk ratio, 0.78 [95% CI, 0.47 to 1.28]; 6 to 68% pregabalin; 4 to 69% placebo) when administered more than 24 h, and an effect of pregabalin on prevalence of moderate/severe pain at 3 months when administered more than 24 h (risk ratio, 0.47 [95% CI, 0.33 to 0.68]; 0 to 20% pregabalin; 4 to 34% placebo). However, the results should be interpreted with caution given small study sizes, variable surgical types, dosages, timing and method of outcome measurements in relation to the acute pain trajectory in question, and preoperative pain status.

CONCLUSIONS

Despite agreement that chronic postsurgical pain is an important topic, extremely little progress has been made since 2013, likely due to study designs being insufficient to address the complexities of this multifactorial problem.

EDITOR’S PERSPECTIVE

Long Term Safety and Efficacy of Sub-Lingual Ketamine Troches / Lozenges in Chronic Non-Malignant Pain Management

INTRODUCTION

Chronic non-malignant pain is a disabling condition that results in a reduction in function and quality of life when inadequately managed. Sub-lingual ketamine has been shown to be efficacious for use in chronic pain. Despite its use for decades in chronic non-malignant pain, there is no published long-term data on safety, side effects or adverse drug reactions. The aim of this case-series is to provide the initial evidence for safety and efficacy in this patient group.

METHODS

We present a retrospective review of twenty-nine patients (n=29) from a metropolitan tertiary pain service who have been receiving sub-lingual ketamine troches / lozenges between the period of 2012-2019. Patients were identified from the outpatient pain clinic, who had been admitted for inpatient subcutaneous ketamine infusions as part of opiate detoxification or management of central sensitisation due to a chronic neuropathic pain syndrome. An initial review was performed to check the patient started taking the ketamine troches. Each of these medical records was reviewed manually to extract information to a datasheet.

RESULTS

There was a wide range of dosages used from 25-600mg in divided doses. The duration of treatment ranged from 2-89 months. There was no association with either the dosage or duration of treatment and frequency of side effects. There was an overall reduction in the use of opioids, gabapentinoids or benzodiazepines in 59% of patients with 39% having a complete cessation of an analgesic agent. Side effects were reported in 24%, but only 7% discontinued the treatment due to the side effect (drowsiness). There were no reports of renal impairment, cystitis, or hepatotoxicity.

DISCUSSION

This retrospective case-series has demonstrated that sub-lingual ketamine is a safe and effective analgesic agent to use in chronic non-malignant pain management. It is indicated in a variety of chronic pain conditions and has an excellent safety profile, with no association between the frequency in side effects and duration of therapy or total daily dosages. The study has also shown that the "safe" dose may be higher than the previous consensus.

CONTRIBUTION STATEMENT

A.A and S.G. recruited the patients. A.A. & B.M. created the parameters for the data collection sheet. B.M Collected most of the data from the medical records, entered it into a datasheet, wrote the manuscript, ran the statistics, performed the data analysis, and generated the figures and tables. A.A. Edited the manuscript. S.G. and A.A were the research supervisors. This article is protected by copyright. All rights reserved.

Enhanced recovery and early extubation after pediatric cardiac surgery using single-dose intravenous methadone

Background/Aims:

Methadone may offer advantages in facilitating early extubation after cardiac surgery, but very few data are available in the pediatric population.

Setting/Design:

Community tertiary children's hospital, retrospective case series.

Materials and Methods:

We performed a retrospective analysis of all pediatric cardiac surgical patients for whom early extubation was intended. A multimodal analgesic regimen was used for all patients, consisting of methadone (0.2–0.3 mg/kg), ketamine (0.5 mg/kg plus 0.25 mg/kg/h), lidocaine (1 mg/kg plus 1.5 mg/kg/h), acetaminophen (15 mg/kg), and parasternal ropivacaine (0.5 mL/kg of 0.2%). Outcome variables were collected with descriptive statistics.

Results:

A total of 24 children [median = 7 (interquartile range = 3.75–13.75) years old, 23.7 (14.8–53.4) kg] were included in the study; 22 (92%) had procedures performed on bypass and 11 (46%) involved a reentry sternotomy. Methadone dosing was 0.26 (0.23–0.29) mg/kg. None of the children required intraoperative supplemental opioids; 23 (96%) were extubated in the operating room. The first p_aCO₂ on pediatric intensive care unit admission was 51 (45–58) mmHg. Time to first supplemental opioid administration was 5.1 (3.5–9.5) h. Cumulative total supplemental opioids (in intravenous morphine equivalents) at 24 and 72 h were 0.2 (0.09–0.32) and 0.42 (0.27–0.68) mg/kg. One child required postoperative bilevel positive airway pressure support, but none required reintubation. None had pruritus; three (13%) experienced nausea.

Conclusion:

A methadone-based multimodal regimen facilitated early extubation without appreciable adverse events. Further investigations are needed to confirm efficacy of this regimen and to assess whether the excellent safety profile seen here holds in the hands of multiple providers caring for a larger, more heterogeneous population.

Ketamine Use in the Surgical Patient: a Literature Review

PURPOSE OF REVIEW

While ketamine is an established anesthetic, its role in the management of acute surgical pain is less certain. Therefore, a literature review is warranted to examine the role of ketamine in acute pain management.

RECENT FINDINGS

The use of ketamine appears to be most efficacious in larger procedures that lead to increased systemic inflammation or extensive tissue damage. In addition, ketamine seems to be most successful when administered consistently throughout a procedure, such as by an infusion instead of a single bolus, in order to have adequate dosing for an analgesic effect. Therefore, the focus of research should be on procedures that lead to moderate to severe pain using frequent dosing to determine the most effective role of ketamine. Most importantly, the current literature shows that ketamine can be used as a successful part of multimodal anesthesia with few side effects in patients undergoing major procedures associated with moderate to severe pain.

Ketamine infusion reduces narcotic requirements following gastric bypass surgery: a randomized controlled trial

BACKGROUND

As the obesity epidemic worsens, anesthesiologists should expect to see more obese patients presenting for surgical procedures. Opioids cause respiratory depression, which has caused complications in patients with obstructive sleep apnea. Opioids can also cause nausea, prolonging the time that patients spend in the postanesthesia care unit. Ketamine is a potential analgesic alternative that may have advantages to narcotics in the bariatric population.

OBJECTIVES

To determine whether an intraoperative ketamine infusion would reduce postoperative narcotic use in patients during the first 48 hours after laparoscopic gastric bypass.

SETTING

Major academic medical center.

METHODS

There were 54 participating patients. The intervention group (n = 27) was randomized to receive 100 μg of fentanyl with anesthesia induction, then a 20-mg bolus of ketamine, followed by a 5 μg/kg/min intraoperative ketamine infusion starting after anesthesia induction and ending after wound closure commenced. The control group (narcotic only, n = 27) also received 100 μg of fentanyl at anesthesia induction and intraoperative boluses of fentanyl at the discretion of the anesthesia team, with .3 mg of hydromorphone administered approximately 45 minutes before the completion of surgery.

RESULTS

At 24 hours, the mean morphine-equivalent units (MEUs) were 12.7 (standard deviation [SD], 9.9; 95% confidence interval [CI], 8.8-16.6) for the ketamine group (n = 28) and 16.5 (SD, 9.8; 95% CI, 12.6-20.4) for the control group (n = 28). At 48 hours, the MEUs were 16.7 (SD, 12.0; 95% CI, 11.9-21.4) for the ketamine group and 22.7 (SD, 14.9; 95% CI, 16.8-28.6) for the control group. Cumulative MEUs for 24 hours (P = .039) and 48 hours (P = .058) postoperatively were lower in the ketamine group compared with the narcotic-only (control) group, although the difference at 48 hours did not reach statistical significance. Compared with the narcotic-only group, the ketamine group used 26% fewer MEUs after 24 hours and 31% fewer MEUs after 48 hours. This difference can mostly be attributed to group differences during the first 6 hours after surgery.

CONCLUSIONS

Ketamine successfully reduced the amount of opioids required to control bariatric patients' pain at 24 hours postoperatively, but not over the 48-hour postoperative period.

Postoperative Pain Management in Pediatric Spinal Fusion Surgery for Idiopathic Scoliosis

This article reviews and summarizes current evidence and knowledge gaps regarding postoperative analgesia after pediatric posterior spine fusion for adolescent idiopathic scoliosis, a common procedure that results in severe acute postoperative pain. Inadequate analgesia may delay recovery, cause patient dissatisfaction, and increase chronic pain risk. Despite significant adverse effects, opioids are the analgesic mainstay after scoliosis surgery. However, growing emphasis on opioid minimization and enhanced recovery has increased adoption of multimodal analgesia (MMA) regimens. While opioid adverse effects remain a concern, MMA protocols must also consider risks and benefits of adjunct medications. We discuss use of opioids via different administration routes and elaborate on the effect of MMA components on opioid/pain and recovery outcomes including upcoming regional analgesia. We also discuss risk for prolonged opioid use after surgery and chronic post-surgical pain risk in this population. Evidence supports use of neuraxial opioids at safe doses, low-dose ketorolac, and methadone for postoperative analgesia. There may be a role for low-dose ketamine in those who are opioid-tolerant or have chronic pain, but the evidence for preoperative gabapentinoids and intravenous lidocaine is currently insufficient. There is a need for further studies to evaluate pediatric-specific optimal MMA dosing regimens after scoliosis surgery. Questions remain regarding how best to prevent acute opioid tolerance, opioid-induced hyperalgesia, and chronic postsurgical pain. We anticipate that this timely update will enable clinicians to develop efficient pain regimens and provide impetus for future research to optimize recovery outcomes after spine fusion.

Comparison of Pupillometry With Surgical Pleth Index Monitoring on Perioperative Opioid Consumption and Nociception During Propofol-Remifentanil Anesthesia: A Prospective Randomized Controlled Trial

BACKGROUND

Intraoperative monitoring with pupillometry has shown promising results for nociception/antinociception balance monitoring. However, its benefits in clinical practice remain unproven. The aim of this study was to evaluate the efficacy of intraoperative pupillometry monitoring on intraoperative opioid consumption and postoperative pain compared to surgical pleth index (SPI), another widely investigated monitoring.

METHODS

American Society of Anesthesiologists (ASA) I-II patients scheduled for elective laparoscopic cholecystectomy were included. This prospective, parallel-arm, single-center study was conducted in 2 steps. First, we evaluated the feasibility of using pupillometry and SPI monitoring compared with conventional hemodynamic monitoring. Next, a parallel-arm, double-blind randomized study compared the peak postoperative pain measured with numerical rating scale (NRS) from 0 (no pain) to 10 (extreme pain) as a primary outcome between pupillometry (pupillometry group, n = 43) and SPI monitoring (SPI group, n = 43) using Mann-Whitney U test. Secondary outcomes included intraoperative remifentanil consumption, postoperative opioid responsiveness (a decrease in NRS by ≥1 after fentanyl administrations), number of analgesic administrations, and opioid-related complications.

RESULTS

In the preliminary study (n = 50), remifentanil consumption was less under pupillometry monitoring compared to SPI monitoring, and peak postoperative pain was lower under pupillometry compared to conventional monitoring. In the main study (n = 86), peak postoperative pain and intraoperative remifentanil consumption were lower in the pupillometry group (median [first to third quartile], 5 [4-6]; mean ± standard deviation [SD], 0.078 ± 0.019 μg·kg·minute) compared to the SPI group (7 [5-8] and 0.0130 ± 0.051 μg·kg·minute; P < .001), with the median difference in peak postoperative pain of -1 and its 95% confidence interval between -2 and -0.5. The pupillometry group had better responsiveness to fentanyl (84.6% vs 61.0%; P = .005) and lower number of analgesic administrations (2 [1-2] vs 2 [1-3]; P = .048) compared to the SPI group.

CONCLUSIONS

Intraoperative pupillometry monitoring reduced intraoperative remifentanil consumption and postoperative pain. It may be an alternative option for intraoperative opioid control under general anesthesia in adult patients.

Ketamine and lidocaine infusions decrease opioid consumption during vaso-occlusive crisis in adolescents with sickle cell disease

PURPOSE OF REVIEW

Recurrent exposure to opioids can lead to development of opioid tolerance and opioid-induced hyperalgesia through activation of N-methyl-D-aspartate receptors. N-methyl-D-aspartate receptor antagonists ketamine and lidocaine can modulate development of opioid tolerance and OIH. This study evaluated the utility of ketamine and/or lidocaine in decreasing opioid consumption during acute pain episodes in adolescents with sickle cell disease. There has been an increased effort to promote opioid-sparing pain relieving methods given the ongoing opioid epidemic.

RECENT FINDINGS

There have been six studies published over the past decade that highlight the ability of ketamine to reduce opioid consumption in the management of sickle cell disease-related pain, primarily in adult patients. There has been one study (2015) that demonstrated a similar benefit with lidocaine, however this was also in adult patients.

SUMMARY

We retrospectively evaluated treatment with ketamine and/or lidocaine infusions in adolescents hospitalized for vaso-occlusive crisis (VOC). Patients served as self-controls using a comparison with a previous control admission for VOC. The use of ketamine and/or lidocaine as adjuncts to opioids resulted in lower daily opioid consumption in three of four patients. Our study suggests that ketamine and/or lidocaine infusions may be useful adjuncts in reducing opioid exposure during VOC pain.

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

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

Ketamine Infusion in Post-Surgical Pain Management after Head and Neck Surgery: A Retrospective Observational Study

Background:

Head and neck cancer affects approximately 382,000 new patients per year worldwide with a significant portion undergoing surgical treatment. During postoperative period key elements in the Intensive Care Unit (ICU) are airway management and pain control.

Objective:

We evaluated the average change of inpatient pain control using a Numerical Rating Score (NRS). We also evaluated the time of extubation after ICU admission recording the incidence of desaturation and the necessity of re-intubation. Secondary outcomes were the incidence of postoperative complications, included those narcotics-related, and the use of rescue analgesics.

Methods:

In this retrospective observational study, we analyzed data of registry before and after we have changed our postoperative analgesic protocol from remifentanil infusion to ketamine infusion.

Results:

Medical records of 20 patients were examined. 10 patients received 0.5 mg/kg ketamine bolus at the end of surgery, followed by a continuous infusion of 0.25 mg/kg/h. All patients presented a significant decrease in pain intensity from the 4th to 48th postoperative hour (p < 0.05), but statically not a significant difference in NRS score was recorded between the two groups. Time to extubation was shorter in ketamine group compared to the remifentanil group (112.30 min ± 16.78 vs. 78 min ± 14.17; p < 0.05). Desaturation rate was 10% in the remifentanil group, while no case was recorded in the ketamine group.

Conclusion:

The level of analgesia provided by ketamine and remifentanil was comparable. Ketamine was superior in ventilatory management of the patient with more rapid extubation and with no case of desaturation.

An Update on the Basic and Clinical Science of Ketamine Analgesia

OBJECTIVE

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

METHODS

We reviewed ketamine analgesia.

RESULTS

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

DISCUSSION

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

Evaluation of Postsurgical Hyperalgesia and Sensitization After Open Inguinal Hernia Repair: A Useful Model for Neuropathic Pain?

Cutaneous mechanical hyperalgesia can be induced in healthy volunteers in early phase analgesic studies to model central sensitization, a key mechanism of persistent pain. However, such hyperalgesia is short-lived (a matter of hours), and is used only for assessing only single drug doses. In contrast, postsurgical peri-incisional hyperalgesia may be more persistent and hence be a more useful model for the assessment of the efficacy of new analgesics. We undertook quantitative sensory testing in 18 patients at peri-incisional and nonoperated sites before open inguinal hernia repair and up to the 24th postsurgical week. The spatial extent of punctate hyperalgesia and brush allodynia at the peri-incisional site were greatest at weeks 2 and 4, but had resolved by week 24. Heat allodynia, suggestive of local inflammation or peripheral sensitization, was not observed; instead, there were deficits in cold and heat sensory detection that persisted until week 24. The findings suggest that central sensitization contributes significantly to mechanical hyperalgesia at the peri-incisional site. The prolonged duration of hyperalgesia would be advantageous as a pain model, but there was considerable variability of mechanical hyperalgesia in the cohort; the challenges of recruitment may limit its use to small, early phase analgesic studies. PERSPECTIVE: Peri-incisional mechanical hyperalgesia persists for ≥4 weeks after open inguinal hernia repair and reflects central sensitization; this may have usefulness as a model of chronic pain to assess the potential of antineuropathic analgesics.

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

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

Intraoperative Ketamine in Total Knee Arthroplasty Does Not Decrease Pain and Narcotic Consumption: A Prospective Randomized Controlled Trial

BACKGROUND

Multiple studies have demonstrated that ketamine, a glutamate receptor blocker, may decrease postoperative pain in abdominal and orthopedic surgeries. However, its role with spinal anesthesia and total knee arthroplasty (TKA) remains unknown. The purpose of this study is to determine the efficacy of subanesthetic dosing of ketamine during TKA on postoperative pain and narcotic consumption.

METHODS

In this prospective, randomized, double-blinded clinical trial, we enrolled 91 patients undergoing primary TKA with spinal anesthesia in a single institution from 2017 to 2018. Patients were randomized to receive intraoperative ketamine infusion at a rate of 6 mcg/kg/min for 75 minutes or a saline placebo. All patients received spinal anesthesia and otherwise identical surgical approaches, pain management, and rehabilitation protocols. Patient-reported visual analog pain scores were calculated preoperatively, postoperative days (POD) 0-7, and 2 weeks. Narcotic consumption was evaluated on POD 0 and 1.

RESULTS

There was no difference in average pain between ketamine and placebo at all time points except for at PODs 1 (45 vs 56, P = .041) and 4 (39 vs 49, P = .040). For least pain experienced, patients administered with ketamine experienced a reduction in pain only at POD 4 (22 vs 35, P = .011). There was no difference in maximum pain cohorts at all time points of the study or in-hospital morphine equivalents between the 2 cohorts.

CONCLUSION

As part of multimodal pain management protocol, intraoperative ketamine does not result in a clinically significant improvement in pain and narcotic consumption following TKA.

Psychological factors predict an unfavorable pain trajectory after hysterectomy: a prospective cohort study on chronic postsurgical pain

Chronic postsurgical pain (CPSP) is a well-recognized potential complication with negative personal, social, and health care consequences. However, limited data exist on CPSP and on the course of pain over time after hysterectomy. Using data from a prospective cohort study on a consecutive sample assessed at 4 time points, presurgery (T1), 48 hours (T2), 4 months (T3), and 5 years postsurgery (T4), we sought to examine women's PSP trajectories using assessments of pain at T3 and T4. In addition, this study aimed to investigate presurgical and postsurgical risk factors associated with an unfavourable pain trajectory (PT). Based on pain data collected at T3 and T4, 3 distinct trajectories of PSP emerged: no CPSP (PT1; n = 88), prolonged PSP (PT2; n = 53), and CPSP (PT3; n = 29). Moreover, reported CPSP prevalence at 5 years was 17.1%. Multinomial logistic regression models controlling for age, presurgical pain, and type of hysterectomy tested for baseline and acute postsurgical predictive variables. Membership in PT2 and PT3 was predicted by presurgical anxiety (odds ratio [OR] = 1.131, P = 0.015; OR = 1.175, P = 0.009, respectively), emotional representation of the surgical disease (OR = 1.155, P = 0.034; OR = 1.213, P = 0.020, respectively), and pain catastrophizing (OR = 1.079, P = 0.043; OR = 1.143, P = 0.001, respectively). Furthermore, acute PSP intensity and frequency determined membership of women in PT3 (OR = 1.211, P = 0.033; OR = 3.000, P = 0.029, respectively), and postsurgical anxiety (OR = 1.182, P = 0.026) also played a key predictive role. This study identified factors that can be easily screened before and after surgery and are amenable to change through carefully designed timely and tailored interventions for women at risk of an unfavorable PSP trajectory posthysterectomy.

Polymelia in a chimeric Simmental calf: nociceptive withdrawal reflex, anaesthetic and analgesic management, anatomic and genetic analysis

BACKGROUND

Polymelia is a congenital defect characterized by one or more supernumerary legs. The genetics and aetiology of this condition in cattle have not yet been thoroughly investigated even though several case reports do exist. The model of the nociceptive withdrawal reflex (NWR) has been characterized in several species to study spinal nociceptive processing. It is a polysynaptic spinal reflex that can be elicited by noxious electrical stimulation and recorded by electromyography. Thorough nociceptive examination and preventive analgesic management has not yet been an aspect in the perioperative management of polymelia cases.

CASE PRESENTATION

A 4-month-old female Simmental calf was presented with notomelia. The animal was in good health and showed no neurologic deficiencies. Preoperatively, computed tomography was performed to gain more detailed anatomical information. To evaluate the sensitivity of the accessory limb, NWR testing was performed and revealed a connection of the afferent reflex pathway of the accessory limb to the efferent of the normal limb. The accessory limb was surgically removed under general anaesthesia. Intensive care included multimodal pain therapy adapted to the pain intensity scored during regular pain assessment. A gross anatomical dissection as well as a genetic analysis of the accessory limb were performed postoperatively. The calf was identified as a chimera.

CONCLUSION

This calf was successfully relieved of its accessory limb. Chimerism has not been described in the congenital defect polymelia. As the accessory limb was pain sensitive and a common nociceptive reflex pathway was identified, thorough perioperative pain management was performed with the intention to prevent chronic neuropathic pain development.

Brain resting-state connectivity in the development of secondary hyperalgesia in healthy men

Central sensitization is a condition in which there is an abnormal responsiveness to nociceptive stimuli. As such, the process may contribute to the development and maintenance of pain. Factors influencing the propensity for development of central sensitization have been a subject of intense debate and remain elusive. Injury-induced secondary hyperalgesia can be elicited by experimental pain models in humans, and is believed to be a result of central sensitization. Secondary hyperalgesia may thus reflect the individual level of central sensitization. The objective of this study was to investigate possible associations between increasing size of secondary hyperalgesia area and brain connectivity in known resting-state networks. We recruited 121 healthy participants (male, age 22, SD 3.35) who underwent resting-state functional magnetic resonance imaging. Prior to the scan session, areas of secondary hyperalgesia following brief thermal sensitization (3 min. 45 °C heat stimulation) were evaluated in all participants. 115 participants were included in the final analysis. We found a positive correlation (increasing connectivity) with increasing area of secondary hyperalgesia in the sensorimotor- and default mode networks. We also observed a negative correlation (decreasing connectivity) with increasing secondary hyperalgesia area in the sensorimotor-, fronto-parietal-, and default mode networks. Our findings indicate that increasing area of secondary hyperalgesia is associated with increasing and decreasing connectivity in multiple networks, suggesting that differences in the propensity for central sensitization, assessed as secondary hyperalgesia areas, may be expressed as differences in the resting-state central neuronal activity.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.

Pain management in living related adult donor hepatectomy: feasibility of an evidence-based protocol in 100 consecutive donors

Objective

Living donor hepatectomy (LDH) has important consequences in terms of acute and chronic pain. We proposed an anesthetic protocol based on the best currently available evidence. We report the results of this protocol’s application.

Results

We performed a retrospective descriptive study of 100 consecutive donors undergoing LDH. The protocol included standardized information provided by the anesthetist, pharmacological anxiolysis and preventive analgesia. Specifically, pregabalin premedication (opioid-free) intravenous anesthesia (with clonidine, ketamine, magnesium sulphate and ketorolac) and epidural analgesia were proposed. Postoperative follow-up was conducted by the Postoperative Pain Service. This analysis included 100 patients (53 women, 47 men, median age 32.7 years old [28.4–37.3]), operated by xypho-umbilical laparotomy. All elements of our anesthetic protocol were applied in over 75% of patients, except for the preoperative consultation with a senior anesthesiologist (55%). The median number of applied item was 7 [interquartile range, IQR 5–7]. Median postoperative pain scores were, at rest and at mobilization respectively 3 [IQR 2–4] and 6 [IQR 4.5–7] on day 1; 2 [IQR 1–3] and 5 [IQR 3–6] on day 2; and 2 [IQR 0–3] and 4 [IQR 3–5] on day 3. In conclusion, LDH leads to severe acute pain. Despite the proposal of a multimodal evidence-based protocol, its applicancy was not uniform and the pain scores remained relatively high.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3941-1) contains supplementary material, which is available to authorized users.

Intraoperative S-ketamine for the reduction of opioid consumption and pain one year after spine surgery: A randomized clinical trial of opioid-dependent patients

BACKGROUND

We aimed to explore the effect of intraoperative S-ketamine on analgesic consumption and pain one year after spine surgery in chronic opioid-dependent patients undergoing spinal fusion surgery.

METHODS

Single-centre, randomized, blinded trial of 147 patients.

INTERVENTION

Perioperative S-ketamine bolus 0.5 mg/kg followed by S-ketamine 0.25 mg kg^-1  hr^-1 infusion or placebo.

MAIN OUTCOMES

Analgesic use, pain (visual analogue scale 0-100 mm [VAS]) and labour market attachment one year after surgery assessed by written questionnaires.

RESULTS

Response rate was 67%. One year after surgery, the daily use of oral morphine equivalents was lower in the ketamine group versus the placebo group: 0 (0-20) mg versus 20 (0-62) mg, (p = 0.02), and fewer patients had a daily use of any analgesics in the ketamine group versus placebo group, 42% (95% CI 23-61) versus 74% (95% CI 58-87), (p = 0.04). Mobilization pain was lower in the ketamine group compared to the placebo group: Median difference 17 mm (95% CI -30 to -3), (p = 0.02). Pain at rest was lower in the ketamine group compared to the placebo group with median difference: 13 mm (95% CI -23 to -3), (p = 0.01). Further, labour market attachment was better in the ketamine group, (p = 0.02).

CONCLUSION

Intraoperative ketamine may reduce analgesic use, pain, and improve labour market attachment one year after spine surgery in a chronic opioid-dependent population.

SIGNIFICANCE

This randomized clinical trial shows that intraoperative ketamine may reduce opioid use and pain and improve labour market attachment one year after spine surgery in an opioid-dependent population.

Persistent Postsurgical Pain

The development of chronic pain is considered a major complication after surgery. Basic science research in animal models helps us understand the transition from acute to chronic pain by identifying the numerous molecular and cellular changes that occur in the peripheral and central nervous systems. It is now well recognized that inflammation and nerve injury lead to long-term synaptic plasticity that amplifies and also maintains pain signaling, a phenomenon referred to as pain sensitization. In the context of surgery in humans, pain sensitization is both responsible for an increase in postoperative pain via the expression of wound hyperalgesia and considered a critical factor for the development of persistent postsurgical pain. Using specific drugs that block the processes of pain sensitization reduces postoperative pain and prevents the development of persistent postoperative pain. This narrative review of the literature describes clinical investigations evaluating different preventative pharmacologic strategies that are routinely used by anesthesiologists in their daily clinical practices for preventing persistent postoperative pain. Nevertheless, further efforts are needed in both basic and clinical science research to identify preclinical models and novel therapeutics targets. There remains a need for more patient numbers in clinical research, for more reliable data, and for the development of the safest and the most effective strategies to limit the incidence of persistent postoperative pain.