Does perioperative ketamine have a role in the prevention of chronic postsurgical pain: the ROCKet trial

The mechanisms and management of persistent postsurgical pain

An estimated 10%-50% of patients undergoing a surgical intervention will develop persistent postsurgical pain (PPP) lasting more than 3 months despite adequate acute pain management and the availability of minimally invasive procedures. The link between early and late pain outcomes for surgical procedures remains unclear-some patients improve while others develop persistent pain. The elective nature of a surgical procedure offers a unique opportunity for prophylactic or early intervention to prevent the development of PPP and improve our understanding of its associated risk factors, such as pre-operative anxiety and the duration of severe acute postoperative pain. Current perioperative pain management strategies often include opioids, but long-term consumption can lead to tolerance, addiction, opioid-induced hyperalgesia, and death. Pre-clinical models provide the opportunity to dissect mechanisms underpinning the transition from acute to chronic, or persistent, postsurgical pain. This review highlights putative mechanisms of PPP, including sensitisation of peripheral sensory neurons, neuroplasticity in the central nervous system and nociceptive signalling along the neuro-immune axis.

Quantitative sensory testing as an assessment tool to predict the response to standard pain treatment in knee osteoarthritis: a systematic review and meta-analysis

Emerging evidence suggest that quantitative sensory testing (QST) may predict the treatment response to pain-relieving therapies. This systematic review and meta-analysis focus on the predictive value of QST for pain management of knee osteoarthritis (OA). MEDLINE and EMBASE were systematically searched for all studies from year 2000 to 2023 on pretreatment QST and treatment of OA including surgical, pharmaceutical, and nonsurgical and nonpharmaceutical therapies. Preclinical studies and reviews were excluded. The systematic review followed the PRISMA guidelines and was pre-registered on the Open Science Framework website (link: https://osf.io/4FETK/, Identifier: DOI 10.17605/OSF.IO/4FETK). Meta-analysis were conducted to demonstrate the strength of the pre-treatment QST predictions on pain outcomes after OA treatments. Sixteen surgical (all on total knee arthroplasty [TKA], N = 1967), 5 pharmaceutical (4 on non-steroidal anti-inflammatory drugs [NSAIDs], N = 271), and 4 exercise-based therapy studies (N = 232) were identified. Pretreatment QST parameters predicted pain-relieving treatment outcomes in 81% of surgical, 100% of pharmaceutical, and 50% of exercise-based therapy studies. Meta-analyses found pretreatment QST profiles to predicted pain outcomes after TKA (random effects: 0.309, 95% confidence interval [CI]: 0.206-0.405, P < 0.001), NSAIDs (random effects: 0.323, 95% CI: 0.194-0.441, P < 0.001), and exercise-based therapies (random effects: 0.417, 95% CI: 0.138-0.635, P = 0.004). The overall risk of bias for the included studies was low to moderate. This systematic review and meta-analysis demonstrate weak-to-moderate associations between pretreatment QST and pain outcomes after standard OA pain treatments. Based on this work, it is hypothesized that a subset of specific pain sensitive patients with OA exist and that these patients do not respond adequately to standard OA pain treatments.

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.

Pain Management of Acute and Chronic Postoperative Pain

Inadequate management of acute postoperative pain is associated with effects related to both physiological and psychological function. Postoperative pain increases the risk of perioperative complications, so postoperative pain should be prevented. Postoperative pain management by sufficient analgesia is important while considering the use of various kinds of analgesics. Insufficient management of postoperative pain may lead to chronic postsurgical pain (CPSP). It is suggested that CPSP is dependent not only upon biological factors but also upon psychological factors, including the type of surgery, age, physical health, mental health, and preoperative pain. As CPSP is a severe complication that may prolong hospitalization and interferes with activities of daily living (ADL) and quality of life (QoL), its prevention of development is paramount. Therefore, in order to prevent the onset of CPSP, it is necessary to craft analgesic management to prevent CPSP during the perioperative period.

Preventing Persistent Postsurgical Pain: A Systematic Review and Component Network Meta-analysis

BACKGROUND AND OBJECTIVES

Evidence for perioperative methods to prevent persistent postsurgical pain (PPP) is uncertain, in part because few treatments have been directly compared. Here we have used component network meta-analysis (cNMA) to incorporate both direct and indirect evidence in the evaluation of the efficacy and tolerability of pharmacological and neural block treatments.

DATABASES AND DATA TREATMENT

We searched the Cochrane Central Registry of Controlled Trials, Embase, MEDLINE, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry up to January 2021, for randomized, double-masked, controlled trials that reported the prevalence of PPP. We assessed trial quality with the Cochrane risk of bias tool (RoB 2.0). We analyzed the results with frequentist cNMA models. The primary outcome was the relative risk (RR) of PPP. We assessed efficacy in relation to a clinically important effect size of RR = 0.9, which is a 10% improvement with treatment.

RESULTS

The analysis included 107 trials (13,553 participants) of 13 treatments. The effects of complex interventions were the multiplicative effects of their components. Compared with placebo, serotonin-norepinephrine reuptake inhibitors (SNRIs), neural block alone, or in combination with NMDA receptor blockers or gabapentanoids were effective. Treatments with benefit in the immediate post-operative period predicted a reduced risk of PPP.

CONCLUSIONS

Several treatments and treatment combinations effectively reduce PPP prevalence. Pain outcomes in the immediate postoperative period are an important mediator of PPP. Multimodal interventions can be analyzed using cNMA.

The expanding role of chronic pain interventions in multimodal perioperative pain management: a narrative review

Surgery is a risk factor for chronic pain and long-term opioid use. As perioperative pain management continues to evolve, treatment modalities traditionally used for chronic pain therapy may provide additional benefit to patients undergoing surgery. Interventions such as radiofrequency ablation, cryoneurolysis, and neuromodulation may potentially be used in conjunction with acute pain procedures such as nerve blocks and multimodal analgesia. Pharmacological agents associated with chronic pain medicine, including gabapentinoids, ketamine, and selective serotonin reuptake inhibitors, may be useful adjuncts in perioperative pain management when indicated. There may also be a role for acupuncture, music therapy, and other integrative medicine therapies. A transitional pain service can help coordinate outpatient care with inpatient perioperative pain management and promote a more personalized and comprehensive approach that can improve postoperative outcomes.

[Prediction and prevention of chronic postoperative pain]

Chronic postoperative pain has been identified as a major medical and socioeconomic problem. A prevention of the chronification processes is potentially possible and preventive treatment could start early (e.g. preoperatively). So far, however, evidence for the effectiveness of preventive strategies is basically low. Important reasons for this dilemma are the lack of appropriate risk assessment as well as effective and mechanism-based preventive (procedure-sepcific) strategies for the chronification process, a lack of stratification of treatment approaches and a so far barely investigated combination of various treatment approaches. In this review article recent findings on the appropriate identification of patients at risk for developing postoperative chronic pain are presented, predictive models for the valid estimation of the individual risk of patients are assessed and studies on pharmaceutical and regional analgesia techniques influencing the pain chronification process are discussed. As a chronification process is, however, extremely complex and dynamic and also necessitates adaptation of the prevention during the course of the process, only combinations of treatment, interdisciplinary and if necessary even longer term approaches might be successful. Future studies are needed to address with which preventive treatment strategies and in which patients chronic pain after surgery can effectively be prevented.

Optimizing Perioperative Use of Opioids: A Multimodal Approach

Purpose of Review

The main purpose of this article is to review recent literature regarding multimodal analgesia medications, citing their recommended doses, efficacy, and side effects. The second part of this report will provide a description of drugs in different stages of development which have novel mechanisms with less side effects such as tolerance and addiction.

Recent Findings

Multimodal analgesia is a technique that facilitates perioperative pain management by employing two or more systemic analgesics along with regional anesthesia, when possible. Even though opioids and non-opioid analgesics remain the most common medication used for acute pain management after surgery, they have many undesirable side effects including the potential for misuse. Newer analgesics including peripheral acting opioids, nitric oxide inhibitors, calcitonin gene-related peptide receptor antagonists, interleukin-6 receptor antagonists and gene therapy are under intensive investigation.

Summary

A patient's first exposure to opioids is often in the perioperative setting, a vulnerable time when multimodal therapy can play a large role in decreasing opioid exposure. Additionally, the current shift towards faster recovery times, fewer post-operative complications and improved cost-effectiveness during the perioperative period has made multimodal analgesia a central pillar of Enhanced Recovery After Surgery (ERAS) protocols.

Intrathecal Morphine Versus Ketamine in Postoperative Pain After Hysterectomy: Double-Blinded, Randomized Clinical Trial

PURPOSE

Abdominal hysterectomy is one of the most commonly performed gynecologic surgical procedures and is frequently associated with moderate to severe pain. The present study compared the effects of morphine and ketamine on postoperative analgesia, hemodynamic stability, and postoperative adverse effects in patients who underwent abdominal hysterectomy.

DESIGN

This randomized controlled trial compares the effects of morphine plus adjuvants to those of ketamine plus adjuvants, administered as spinal anesthetic agents in patients who underwent abdominal hysterectomy.

METHODS

Eighty patients were randomly assigned to two different groups: group M (morphine, 40 mcg) and group K (ketamine, 20 mg); the anesthetic agents were combined with equal quantities of other adjuvants. Postoperative analgesia was evaluated by means of a numeric pain rating scale; adverse effects (pruritus, nausea and vomiting, urinary retention, respiratory depression, and changes in bowel habits) at specific postoperative time intervals of T1 (4 hours), T2 (12 hours), and T3 (24 hours) were documented and compared. Hemodynamic stability was assessed intraoperatively.

FINDINGS

Both groups displayed similar patient characteristics, comorbidities, paravertebral block level, and intraoperative hemodynamics. The present study observed a significant difference in postoperative analgesia between the two groups, 12 hours after the surgery, with group M exhibiting better results, compared with group K (P = .004). The pain scores obtained from group K were consistent with the amount of rescue medication (tramadol) administered to the subjects in the group, which showed a concomitant higher consumption of tramadol, compared with group M (42.5 and 71.8 mg in group M and group K, respectively, P = .011). Group M showed a higher incidence of pruritus, changes in bowel habits, and constipation compared with group K.

CONCLUSIONS

Compared with ketamine, intrathecal morphine obtained better postoperative analgesia up to 12 hours after surgery, with a higher incidence of pruritus without any significant change in other variables.

Mechanism-based pain management in chronic pancreatitis - is it time for a paradigm shift?

INTRODUCTION

Pain is the most common symptom in chronic pancreatitis and treatment remains a challenge. Management of visceral pain, in general, is only sparsely documented, and treatment in the clinic is typically based on empirical knowledge from somatic pain conditions. This may be problematic, as many aspects of the neurobiology differ significantly from somatic pain, and organs such as the gut and liver play a major role in tolerability to analgesics. On the other hand, clinical awareness and new methods for quantitative assessment of pain mechanisms, will likely increase our understanding of the visceral pain system and guide more individualized pain management. Areas covered: This review includes an overview of known pain mechanisms in chronic pancreatitis and how to characterize them using quantitative sensory testing. The aim is to provide a mechanism-oriented approach to analgesic treatment, including treatment of psychological factors affecting pain perception and consideration of side effects in the management plan. Expert opinion: A mechanism-based examination and profiling of pain in chronic pancreatitis will enable investigators to provide a well-substantiated approach to effective management. This mechanism-based, individualized regime will pave the road to better pain relief and spare the patient from unnecessary trial-and-error approaches and unwanted side effects.