The impact of ketamine on pain-related outcomes after thoracotomy: a systematic review with meta-analysis of randomized controlled trials

Objective

This meta-analysis aims to examine how effective ketamine is in the management of acute and preventing chronic post-thoracotomy pain by synthesizing the available research.

Method

A systematic literature search was conducted across PubMed, Scopus, and Cochrane Library till May 2023. Randomized Controlled Trials (RCT) examining the influence of ketamine on post-thoracotomy pain in adults were included. The intervention group included ketamine plus morphine, while the control group included morphine only. The outcome measures were opioid intake and pain scores at rest and on moving/coughing. Evidence quality was evaluated using the Cochrane Risk of Bias and GRADE assessment.

Results

Nine articles comprising 556 patients were selected for meta-analysis. The intervention group had a significant decrease in pain at rest (Std. Mean Difference (SMD = -0.60 with 95% CI [-0.83, -0.37]) and on movement/cough (SMD = -0.73 [-1.27, -0.18]) in the first postoperative days. Also, the ketamine group had lower opioid consumption (mg) in comparison with controls (SMD = -2.75 [-4.14, -1.36], p-value = 0.0001) in postoperative days 1-3. There was no data to assess the long-term effect of ketamine on chronic pain.

Conclusion

This meta-analysis shows that ketamine use can lower acute pain levels and morphine use after thoracotomy. In the future, larger RCTs using standardized methods and assessing both short-term and long-term analgesic effects of ketamine are necessary to deepen the understanding of the issue.

Perioperative Pain Management for Thoracic Surgery: A Multi-Layered Approach

Cardiothoracic surgeries frequently pose unique challenges in the management of perioperative acute pain that require a multifaceted and personalized approach in order to optimize patient outcomes. This article discusses various analgesic strategies including regional anesthesia techniques such as thoracic epidurals, erector spinae plane blocks, and serratus anterior plane blocks and underscores the significance of perioperative multimodal medications, while providing nuanced recommendations for their use. This article further attempts to provide evidence for the efficacy of the different modalities and compares the effectiveness of the choice of analgesia. The roles of Acute Pain Services (APS) and Transitional Pain Services (TPS) in mitigating opioid dependence and chronic postsurgical pain are also discussed. Precision medicine is also presented as a potential way to offer a patient tailored analgesic strategy. Supported by various randomized controlled trials and meta-analyses, the article concludes that an integrated, patient-specific approach encompassing regional anesthesia and multimodal medications, while also utilizing the services of the Acute Pain Service can help to enhance pain management outcomes in cardiothoracic surgery.

Efficacy and safety of perioperative ketamine for the prevention of chronic postsurgical pain: A meta-analysis

STUDY OBJECTIVE

Assessment of the efficacy and safety of perioperative intravenous ketamine in reducing incidence and severity of chronic postsurgical pain.

STUDY DESIGN

A systematic review and meta-analysis of randomized controlled trials (RCTs).

DATA SOURCES

The following data sources were systematically searched: MEDLINE, CENTRAL, and EMBASE (till 02/2021).

PATIENTS

Adult patients undergoing any surgery.

INTERVENTIONS

Perioperative use of intravenous ketamine as an additive analgesic drug compared to placebo, no active control treatment, and other additive drugs.

MEASUREMENTS

Primary outcomes were number of patients with chronic postsurgical pain after 6 months and ketamine related adverse effects. Secondary outcomes were chronic postsurgical pain incidence after 3 and 12 months, chronic postsurgical neuropathic pain incidence, chronic postsurgical moderate to severe pain incidence, intensity of chronic postsurgical pain at rest, and during movement, oral morphine consumption after 3, 6, and 12 months and incidence of opioid-related adverse effects.

MAIN RESULTS

Thirty-six RCTs were included with a total of 3572 patients. Ketamine compared to placebo may result in no difference in the number of patients with chronic postsurgical pain after 6 months (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.71-1.05; I2  = 34%; 16 studies; low-certainty evidence). Ketamine may reduce the incidence of chronic postsurgical neuropathic pain after 3 months in comparison to placebo (RR 0.78, 95% CI 0.62-0.99, I2  = 31%, seven trials, low-certainty evidence). Ketamine compared to placebo may increase the risk for postoperative nystagmus (RR 9.04, 95% CI 1.15-70.90, I2 30%, two trials, low-certainty evidence) and postoperative visual disturbances (RR 2.29, 95% CI 1.05-4.99, I2 10%, seven trials, low-certainty evidence).

CONCLUSIONS

There is low-certainty evidence that perioperative ketamine has no effect on chronic postsurgical pain in adult patients. Low-certainty evidence suggests that ketamine compared to placebo may reduce incidence of chronic postsurgical neuropathic pain after 3 months. Questions like ideal dosing, treatment duration and more patient-related outcome measures remain unanswered, which warrants further studies.

PROTOCOL REGISTRATION

Prospero CRD42021223625, 07.01.2021.

ED90 of epidural esketamine with 0.075% ropivacaine for labor analgesia in nulliparous parturients: a prospective, randomized and dose-finding study

Background: Because it has been reported that racemic ketamine had a local anesthetic-sparing effect when used for epidural analgesia this would suggest the likelihood of a potential advantage (less pruritus) over opioid drugs. Esketamine has greater analgesic efficacy than racemic ketamine, but the optimum dosage regimen for epidural use is undetermined. The aim of this study was to determine the ED₉₀ of epidural esketamine when coadministered with 0.075% ropivacaine for labor analgesia. Methods: A total of 65 laboring nulliparous patients were enrolled in this study from 16 March 2022 to 15 October 2022. The patients were randomly assigned to receive 0, 0.25, 0.5, 0.75 or 1.0 mg/mL esketamine with 0.075% ropivacaine epidurally. An effective response to the epidural loading dose was defined as numerical rating scale pain score ≤3 at 30 min after the end of the epidural loading dose (10 mL of the ropivacaine 0.075% solution with the added esketamine). The ED₉₀ of epidural esketamine coadministered with 0.075% ropivacaine with 95% confidence intervals for labor analgesia was determined using probit regression. Secondary outcomes and side effects were recorded. Results: The estimated value of ED₉₀ with 95% CIs for epidural esketamine with 0.075% ropivacaine was 0.983 (0.704-2.468) mg/mL. The characteristics of sensory and motor block, consumption of ropivacaine per hour, duration of first or second stage, Apgar scores did not differ among the five groups. The incidence of mild dizziness in Group esketamine 1.0 mg/mL was significantly higher than that in other groups (p < 0.05). No statistical differences were found in other side effects among groups. Conclusion: The ED₉₀ value of epidural esketamine coadministered with 0.075% ropivacaine for labor analgesia in nulliparous parturients was about 1.0 mg/mL. Furthermore, our results suggested that epidural esketamine would cause dose-dependent mild dizziness especially at doses up to 1.0 mg/mL. As a single epidural additive, esketamine may not be suitable for labor analgesia. Future studies may investigate the appropriate dosage of esketamine at slightly higher concentrations of local anesthetics or larger initial volume of analgesia, or explore other potential advantages of esketamine. Clinical Trial Registration: (https://www.chictr.org.cn/bin/project/edit?pid=159764), identifier (ChiCTR2200057662).

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Regional anesthesia and acute perioperative pain management in thoracic surgery: a narrative review

Background and Objective

Thoracic surgery causes significant pain which can negatively affect pulmonary function and increase risk of postoperative complications. Effective analgesia is important to reduce splinting and atelectasis. Systemic opioids and thoracic epidural analgesia (TEA) have been used for decades and are effective at treating acute post-thoracotomy pain, although both have risks and adverse effects. The advancement of thoracoscopic surgery, a focus on multimodal and opioid-sparing analgesics, and the development of ultrasound-guided regional anesthesia techniques have greatly expanded the options for acute pain management after thoracic surgery. Despite the expansion of surgical techniques and analgesic approaches, there is no clear optimal approach to pain management. This review aims to summarize the body of literature regarding systemic and regional anesthetic techniques for thoracic surgery in both thoracotomy and minimally invasive approaches, with a goal of providing a foundation for providers to make individualized decisions for patients depending on surgical approach and patient factors, and to discuss avenues for future research.

Methods

We searched PubMed and Google Scholar databases from inception to May 2021 using the terms “thoracic surgery”, “thoracic surgery AND pain management”, “thoracic surgery AND analgesia”, “thoracic surgery AND regional anesthesia”, “thoracic surgery AND epidural”. We considered articles written in English and available to the reader.

Key Content and Findings

There is a wide variety of strategies for treating acute pain after thoracic surgery, including multimodal opioid and non-opioid systemic analgesics, regional anesthesia including TEA and paravertebral blocks (PVB), and a recent expansion in the use of novel fascial plane blocks especially for thoracoscopy. The body of literature on the effectiveness of different approaches for thoracotomy and thoracoscopy is a rapidly expanding field and area of active debate.

Conclusions

The optimal analgesic approach for thoracic surgery may depend on patient factors, surgical factors, and institutional factors. Although TEA may provide optimal analgesia after thoracotomy, PVB and emerging fascial plane blocks may offer effective alternatives. A tailored approach using multimodal systemic therapies and regional anesthesia is important, and future studies comparing techniques are necessary to further investigate the optimal approach to improve patient outcomes.

Ketamine for the Treatment of Chronic Pain: A Comprehensive Review

Background

Chronic pain significantly worsens the quality of life. Unlike neuropathic, musculoskeletal, postoperative pain, and cancer pain, chronic primary pain cannot be explained by an underlying disease or condition, making its treatment arduous.

Objectives

This manuscript intends to provide a comprehensive review of the use of ketamine as a treatment option for specific chronic pain conditions.

Study Design

A review article.

Setting

A review of the literature.

Methods

A search was done on PubMed for relevant articles.

Results

A comprehensive review of the current understanding of chronic pain and the treatment of specific chronic pain conditions with ketamine.

Limitations

Literature is scarce regarding the use of ketamine for the treatment of chronic pain.

Conclusion

First-line treatment for many chronic pain conditions includes NSAIDs, antidepressants, anticonvulsants, and opioids. However, these treatment methods are unsuccessful in a subset of patients. Ketamine has been explored in randomized controlled trials (RCTs) as an alternative treatment option, and it has been demonstrated to improve pain symptoms, patient satisfaction, and quality of life. Conditions highlighted in this review include neuropathic pain, fibromyalgia, complex regional pain syndrome (CRPS), phantom limb pain (PLP), cancer pain, and post-thoracotomy pain syndrome. This review will discuss conditions, such as neuropathic pain, fibromyalgia, complex regional pain syndrome, and more and ketamine's efficacy and its supplementary benefits in the chronic pain patient population. As the opioid crisis in the United States continues to persist, this review aims to understand better multimodal analgesia, which can improve how chronic pain is managed.

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).

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

Paravertebral Block Versus Preemptive Ketamine Effect on Pain Intensity after Posterolateral Thoracotomies: A Randomized Controlled Trial

Severe postoperative pain affects most patients after thoracotomy and is a risk factor for post-thoracotomy pain syndrome (PTPS). This randomized controlled trial compared preemptively administered ketamine versus continuous paravertebral block (PVB) versus control in patients undergoing posterolateral thoracotomy. The primary outcome was acute pain intensity on the visual analog scale (VAS) on the first postoperative day. Secondary outcomes included morphine consumption, patient satisfaction, and PTPS assessment with Neuropathic Pain Syndrome Inventory (NPSI). Acute pain intensity was significantly lower with PVB compared to other groups at four out of six time points. Patients in the PVB group used significantly less morphine via a patient-controlled analgesia pump than participants in other groups. Moreover, patients were more satisfied with postoperative pain management after PVB. PVB, but not ketamine, decreased PTPS intensity at 1, 3, and 6 months after posterolateral thoracotomy. Acute pain intensity at hour 8 and PTPS intensity at month 3 correlated positively with PTPS at month 6. Bodyweight was negatively associated with chronic pain at month 6. Thus, PVB but not preemptively administered ketamine decreases both acute and chronic pain intensity following posterolateral thoracotomies.

Effect of opioid-free anaesthesia on postoperative epidural ropivacaine requirement after thoracic surgery: A retrospective unmatched case-control study

INTRODUCTION

Patients undergoing thoracic surgery are at risk of severe postoperative pain. Post-thoracotomy pain relief is usually provided with thoracic epidural analgesia (TEA). Intraoperative use of opioids may result in hyperalgesia and increase analgesics consumption. We investigated the effect of opioid-free anaesthesia (OFA) on epidural ropivacaine requirement after thoracotomy.

METHODS

This retrospective study compared postoperative epidural ropivacaine requirement of patients undergoing open thoracotomy and receiving either opioid-based anaesthesia (OBA group) or a non-opioid regimen including clonidine, ketamine and lidocaine (OFA group). All patients received postoperative multimodal analgesia including both epidural analgesia and intravenous analgesics. The primary outcome was the cumulative first 48 postoperative hours epidural ropivacaine consumption. Secondary outcomes included postoperative pain scores, requirement for postoperative morphine titration, total opioid analgesics consumption within the first 48 postoperative hours, incidence of nausea and vomiting, intraoperative haemodynamic.

RESULTS

From January 2015 to February 2018, 50 patients received an OBA and 25 received an OFA. The cumulative first 48 postoperative hours epidural ropivacaine consumption was significantly higher in the OBA-group (919 ± 311 mg versus 693 ± 270 mg, P = 0.002). Numerical Rating Scale at 6 and 24 h were significantly lower in the OFA-group (1[0-2] versus 3 [1-5], P = 0.0005 and 1[0-2] versus 3.5 [1-5], P = 0.001). In post-anaesthesia care unit, the proportion of patients requiring morphine was significantly higher in the OBA-group (42% versus 4%, P < 0.001). During anaesthesia, the OBA-group required more vasopressor support, while there were more hypertensive events in the OFA-group.

CONCLUSION

OFA might reduce ropivacaine consumption, early postoperative pain scores and requirement for morphine titration after thoracotomy.

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.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 39 studies, enrolling a total of 3027 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 41 studies, enrolling a total of 3143 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Assessment and manifestation of central sensitisation across different chronic pain conditions

Different neuroplastic processes can occur along the nociceptive pathways and may be important in the transition from acute to chronic pain and for diagnosis and development of optimal management strategies. The neuroplastic processes may result in gain (sensitisation) or loss (desensitisation) of function in relation to the incoming nociceptive signals. Such processes play important roles in chronic pain, and although the clinical manifestations differ across condition processes, they share some common mechanistic features. The fundamental understanding and quantitative assessment of particularly some of the central sensitisation mechanisms can be translated from preclinical studies into the clinic. The clinical perspectives are implementation of such novel information into diagnostics, mechanistic phenotyping, prevention, personalised treatment, and drug development. The aims of this paper are to introduce and discuss (1) some common fundamental central pain mechanisms, (2) how they may translate into the clinical signs and symptoms across different chronic pain conditions, (3) how to evaluate gain and loss of function using quantitative pain assessment tools, and (4) the implications for optimising prevention and management of pain. The chronic pain conditions selected for the paper are neuropathic pain in general, musculoskeletal pain (chronic low back pain and osteoarthritic pain in particular), and visceral pain (irritable bowel syndrome in particular). The translational mechanisms addressed are local and widespread sensitisation, central summation, and descending pain modulation.

Significance

Central sensitisation is an important manifestation involved in many different chronic pain conditions. Central sensitisation can be different to assess and evaluate as the manifestations vary from pain condition to pain condition. Understanding central sensitisation may promote better profiling and diagnosis of pain patients and development of new regimes for mechanism based therapy. Some of the mechanisms underlying central sensitisation can be translated from animals to humans providing new options in development of therapies and profiling drugs under development.

Design and implementation of an enhanced recovery program in thoracic surgery

Despite significant improvements in perioperative care, major surgery is still associated with major complications. Enhanced recovery after surgery was introduced by the National Health Service in the UK with the aim of improving patient outcomes and reducing length of stay in hospital. The degree of applicability differs between surgical specialties, and in thoracic surgery it has not been developed until recently. We have therefore reviewed recent literature specific to thoracic surgery, and will discuss key elements of the design, implementation and monitoring of an enhanced recovery (ER) program based on our recent experience. The program is divided into several high impact intervention measures that involve the preoperative, intraoperative and postoperative periods. Physical activity promotion and educational programs that provide information about the surgery and the surgical pathway are an essential part of the preoperative strategies. During surgery, an optimal pain control strategy, antibiotic prophylaxis and protective ventilation are important. Minimally invasive surgery and well-planned postoperative care including early drain removal and planned discharge are also important. Overall, we have shown that ER in thoracic surgery can facilitate early discharge from hospital and possibly reduce postoperative complications. Further studies are required to understand the extent of ER benefits when applied to thoracic surgery, and to test individual components in a prospective manner.

Oral ketamine for the treatment of pain and treatment-resistant depression†

BACKGROUND

Recent studies with intravenous (i.v.) application of ketamine show remarkable but short-term success in patients with MDD. Studies in patients with chronic pain have used different ketamine applications for longer time periods. This experience may be relevant for psychiatric indications.

AIMS

To review the literature about the dosing regimen, duration, effects and side-effects of oral, intravenous, intranasal and subcutaneous routes of administration of ketamine for treatment-resistant depression and pain.

METHOD

Searches in PubMed with the terms 'oral ketamine', 'depression', 'chronic pain', 'neuropathic pain', 'intravenous ketamine', 'intranasal ketamine' and 'subcutaneous ketamine' yielded 88 articles. We reviewed all papers for information about dosing regimen, number of individuals who received ketamine, number of ketamine days per study, results and side-effects, as well as study quality.

RESULTS

Overall, the methodological strength of studies investigating the antidepressant effects of ketamine was considered low, regardless of the route of administration. The doses for depression were in the lower range compared with studies that investigated analgesic use. Studies on pain suggested that oral ketamine may be acceptable for treatment-resistant depression in terms of tolerability and side-effects.

CONCLUSIONS

Oral ketamine, given for longer time periods in the described doses, appears to be well tolerated, but few studies have systematically examined the longer-term negative consequences. The short- and longer-term depression outcomes as well as side-effects need to be studied with rigorous randomised controlled trials.

Best practice in the administration of analgesia in postoncological surgery

The rationale for using multimodal analgesia after any major surgery is achievement of adequate analgesia while avoiding the unwanted effects of large doses of any analgesic, in particular opioids. There are two reasons why we can hypothesize that multimodal analgesia might have a significant impact on cancer-related outcomes in the context of oncological orthopedic surgery. First, because multimodal analgesia is a key component of enhanced-recovery pathways and can accelerate return to intended oncological therapy. And second, because some of the analgesic used in multimodal analgesia (i.e., COX inhibitors, local analgesics and dexamethasone) can induce apoptosis in cancer cells and/or diminish the inflammatory response during surgery which itself can facilitate tumor growth.

Is pre-emptive administration of ketamine a significant adjunction to intravenous morphine analgesia for controlling postoperative pain? A randomized, double-blind, placebo-controlled clinical trial

OBJECTIVES

To evaluate if the pre-emptive administration of ketamine would potentiate the effect of intravenous morphine analgesia in the management of post-thoracotomy pain.

METHODS

This was a unicentre, double-blind, placebo-controlled, parallel-group, prospective study. Patients were randomly assigned to receive 1 mg/kg ketamine (ketamine group) or an equivalent dose of normal saline (placebo group) before thoracotomy in 1:1 ratio. All patients received postoperatively intravenous morphine administration as additional analgesic regimen. Primary end-point was the pain relief measured with Visual Analogue Scale at rest. The secondary end-points were the reduction of inflammatory response expressed by plasma C-reactive protein levels, the morphine consumption and the rate of side effects. The measurements were carried out 6, 12, 24, 36 and 48 hours postoperatively.

RESULTS

A total of 75 patients were randomized of whom 38 were allocated to ketamine group and 37 to placebo group. Baseline characteristics were comparable. Ketamine compared with placebo group showed a significant reduction of pain scores (P = 0.01), C-reactive protein (P < 0.001) and morphine consumption (P < 0.001). No acute psychological side effects related to the use of ketamine were registered.

CONCLUSIONS

The administration of ketamine before surgery may be an effective adjunct to intravenous morphine analgesia in acute post-thoracotomy pain management. In ketamine group, satisfaction of pain relief was significantly higher with a significant reduction of inflammatory response and morphine consumption compared with placebo group. Our results, if confirmed by larger studies, may be of clinical relevance in situations where epidural analgesia or other analgesic procedures different from systemic opioid analgesia are unavailable or contraindicated.

Intra- and postoperative intravenous ketamine does not prevent chronic pain: A systematic review and meta-analysis

Background and aims

The development of postoperative chronic pain (POCP) after surgery is a major problem with a considerable socioeconomic impact. It is defined as pain lasting more than the usual healing, often more than 2–6 months. Recent systematic reviews and meta-analyses demonstrate that the N-methyl-D-aspartate-receptor antagonist ketamine given peri- and intraoperatively can reduce immediate postoperative pain, especially if severe postoperative pain is expected and regional anaesthesia techniques are impossible. However, the results concerning the role of ketamine in preventing chronic postoperative pain are conflicting. The aim of this study was to perform a systematic review and a pooled analysis to determine if peri- and intraoperative ketamine can reduce the incidence of chronic postoperative pain.

Methods

Electronic searches of PubMed, EMBASE and Cochrane including data until September 2013 were conducted. Subsequently, the titles and abstracts were read, and reference lists of reviews and retrieved studies were reviewed for additional studies. Where necessary, authors were contacted to obtain raw data for statistical analysis. Papers reporting on ketamine used in the intra- and postoperative setting with pain measured at least 4 weeks after surgery were identified. For meta-analysis of pain after 1, 3, 6 and 12 months, the results were summarised in a forest plot, indicating the number of patients with and without pain in the ketamine and the control groups. The cut-off value used for the VAS/NRS scales was 3 (range 0–10), which is a generally well-accepted value with clinical impact in view of quality of life.

Results

Our analysis identified ten papers for the comprehensive meta-analysis, including a total of 784 patients. Three papers, which included a total of 303 patients, reported a positive outcome concerning persistent postsurgical pain. In the analysis, only one of nine pooled estimates of postoperative pain at rest or in motion after 1, 3, 6 or 12 months, defined as a value ≥3 on a visual analogue scale of 0–10, indicated a marginally significant pain reduction.

Conclusions

Based on the currently available data, there is currently not sufficient evidence to support a reduction in chronic pain due to perioperative administration of ketamine. Only the analysis of postoperative pain at rest after 1 month resulted in a marginally significant reduction of chronic postoperative pain using ketamine in the perioperative setting.

Implications

It can be hypothesised, that regional anaesthesia in addition to the administration of perioperative ketamine might have a preventive effect on the development of persistent postsurgical pain. An additional high-quality pain relief intra- and postoperatively as well after discharge could be more effective than any particular analgesic method per se. It is an assumption that a low dose infusion ketamine has to be administered for more than 72 h to reduce the risk of chronic postoperative pain.

A systematic review and meta-analysis of ketamine for the prevention of persistent post-surgical pain

While post-operative pain routinely resolves, persistent post-surgical pain (PPSP) is common in certain surgeries; it causes disability, lowers quality of life and has economic consequences. The objectives of this systematic review and meta-analysis were to evaluate the effectiveness of ketamine in reducing the prevalence and severity of PPSP and to assess safety associated with its use. We searched the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE through December 2012 for articles in any language. We included randomized, controlled trials in adults in which ketamine was administered perioperatively via any route. Seventeen studies, the majority of which administered ketamine intravenously, met all inclusion criteria. The overall risk of developing PPSP was not significantly reduced at any time point in the ketamine group vs. placebo, nor did comparisons of pain severity scores reach statistical significance. Sensitivity analysis of exclusively intravenous ketamine studies included in this meta-analysis demonstrated statistically significant reductions in risk of developing PPSP at 3 and 6 months (P = 0.01 and P = 0.04, respectively). Adverse event rates were similar between ketamine and placebo groups. The study data from our review are heterogeneous and demonstrate efficacy of intravenously administered ketamine only in comparison with placebo. Highly variable timing and dosing of ketamine in these studies suggest that no unifying effective regimen has emerged. Future research should focus on clinically relevant outcomes, should stratify patients with pre-existing pain and possible central sensitization and should enroll sufficiently large numbers to account for loss to follow-up in long-term studies.

A systematic review of therapeutic interventions to reduce acute and chronic post-surgical pain after amputation, thoracotomy or mastectomy

Background

Perioperative neuropathic pain is under-recognized and often undertreated. Chronic pain may develop after any routine surgery, but it can have a far greater incidence after amputation, thoracotomy or mastectomy. The peak noxious barrage due to the neural trauma associated with these operations may be reduced in the perioperative period with the potential to reduce the risk of chronic pain.

Databases and data treatment

A systematic review of the evidence for perioperative interventions reducing acute and chronic pain associated with amputation, mastectomy or thoracotomy.

Results

Thirty-two randomized controlled trials met the inclusion criteria. Gabapentinoids reduced pain after mastectomy, but a single dose was ineffective for thoracotomy patients who had an epidural. Gabapentinoids were ineffective for vascular amputees with pre-existing chronic pain. Venlafaxine was associated with less chronic pain after mastectomy. Intravenous and topical lidocaine and perioperative EMLA (eutectic mixture of local anaesthetic) cream reduced the incidence of chronic pain after mastectomy, whereas local anaesthetic infiltration appeared ineffective. The majority of the trials investigating regional analgesia found it to be beneficial for chronic symptoms. Ketamine and intercostal cryoanalgesia offered no reduction in chronic pain. Total intravenous anaesthesia (TIVA) reduced the incidence of post-thoracotomy pain in one study, whereas high-dose remifentanil exacerbated chronic pain in another.

Conclusions

Appropriate dose regimes of gabapentinoids, antidepressants, local anaesthetics and regional anaesthesia may potentially reduce the severity of both acute and chronic pain for patients. Ketamine was not effective at reducing chronic pain. Intercostal cryoanalgesia was not effective and has the potential to increase the risk of chronic pain. TIVA may be beneficial but the effects of opioids are unclear.

Does intravenous ketamine enhance analgesia after arthroscopic shoulder surgery with ultrasound guided single-injection interscalene block?: a randomized, prospective, double-blind trial

Ketamine has anti-inflammatory, analgesic and antihyperalgesic effect and prevents pain associated with wind-up. We investigated whether low doses of ketamine infusion during general anesthesia combined with single-shot interscalene nerve block (SSISB) would potentiate analgesic effect of SSISB. Forty adult patients scheduled for elective arthroscopic shoulder surgery were enrolled and randomized to either the control group or the ketamine group. All patients underwent SSISB and followed by general anesthesia. During an operation, intravenous ketamine was infused to the patients of ketamine group continuously. In control group, patients received normal saline in volumes equivalent to ketamine infusions. Pain score by numeric rating scale was similar between groups at 1, 6, 12, 24, 36, and 48 hr following surgery, which was maintained lower than 3 in both groups. The time to first analgesic request after admission on post-anesthesia care unit was also not significantly different between groups. Intraoperative low dose ketamine did not decrease acute postoperative pain after arthroscopic shoulder surgery with a preincisional ultrasound guided SSISB. The preventive analgesic effect of ketamine could be mitigated by SSISB, which remains one of the most effective methods of pain relief after arthroscopic shoulder surgery.

Prolonged perioperative infusion of low-dose ketamine does not alter opioid use after pediatric scoliosis surgery

BACKGROUND

Opioid consumption after posterior spinal fusion is known to be high and often exceeds those reported in other major surgical procedures. A number of clinical trials provide evidence that the perioperative use of subanesthetic doses of ketamine reduces pain and opioid requirements in some surgical procedures, but the effect of prolonged perioperative low-dose ketamine infusion in patients undergoing posterior spinal fusion for pediatric scoliosis surgery is unknown.

OBJECTIVE

To test the hypothesis that a 72-h perioperative low-dose ketamine infusion would decrease opioid use in pediatric patients undergoing posterior spinal fusion.

METHODS

In a double-blind prospective controlled trial, patients undergoing posterior spinal fusion for scoliosis were randomized to receive perioperative low-dose ketamine or placebo control. Patients received general anesthesia, intraoperative remifentanil, and morphine patient-controlled analgesia postoperatively. Daily opioid consumption, self-reported pain scores, and sedation scores were measured.

RESULTS

Fifty-four patients were enrolled and 50 completed the study. Contrary to our hypothesis, ketamine- and control-treated patients had similar postoperative opioid use, pain scores, and sedation scores measurements. In contrast, ketamine-treated patients required less intraoperative remifentanil compared with control (mean 2.9 mg vs. 4 mg, P = 0.0415). Number of vertebrae instrumented, time between end-of-surgery and 24 h assessment, or remifentanil doses did not impact on postoperative opioid use. Over 96-h postoperatively, morphine-equivalent consumption was lower (-0.40, P = 0.006) and sedation score was higher (0.47, P = 0.0211) in male patients, compared with female patients.

CONCLUSIONS

These findings do not support the use of perioperative low-dose ketamine to decrease opioid use in children with scoliosis undergoing posterior spinal fusion.

Post-surgical pain syndromes: a review for the non-pain specialist

PURPOSE

This is a selective narrative review of the latest information about the epidemiology, impact, and prevention of chronic post-surgical pain (CPSP), intended primarily for those without a special interest in pain medicine.

PRINCIPAL FINDINGS

Chronic post-surgical pain is an important problem in terms of personal impact. It has staggering economic implications, exerts powerful negative effects on the quality of life of many of those it afflicts, and places a significant burden on chronic pain treatment services in general. It is well known that surgery at certain body sites is apt to cause CPSP, but emerging evidence shows a strong correlation between CPSP and demographic (young age, obesity, and female sex) and psychological characteristics (anxiety, depression, stress, and catastrophizing). Severe acute pain is a strong risk factor for CPSP, and this adds yet more weight to the argument that acute pain should be controlled effectively. In specific circumstances, CPSP can be reduced by regional anesthetic techniques, infiltration of local anesthetic, or preoperative use of gabapentin. The ability of other known interrupters of afferent nociceptive transmission-commonly used to reduce CPSP when administered at the time of surgery-is currently unproven, as is the hypothesis that the use of remifentanil during surgery worsens CPSP.

CONCLUSIONS

Reduction of CPSP is a worthy long-term outcome for anesthesia providers to consider as they plan the perioperative care of their patients. More evidence is needed about the effect of currently used analgesics and other perioperative techniques on CPSP.