Perioperative pregabalin administration does not prevent chronic postoperative pain: systematic review with a meta-analysis of randomized trials

Comparative benefits and harms of perioperative interventions to prevent chronic pain after orthopedic surgery: a systematic review and network meta-analysis of randomized trials

BACKGROUND

Chronic postsurgical pain (CPSP) is common following musculoskeletal and orthopedic surgeries and is associated with impairment and reduced quality of life. Several interventions have been proposed to reduce CPSP; however, there remains uncertainty regarding which, if any, are most effective. We will perform a systematic review and network meta-analysis of randomised trials to assess the comparative benefits and harms of perioperative pharmacological and psychological interventions directed at preventing chronic pain after musculoskeletal and orthopedic surgeries.

METHODS

We will search MEDLINE, Embase, PsycINFO, CINAHL, and the Cochrane Central Register of Controlled Trials from inception to present, without language restrictions. We will include randomised controlled trials that as follows: (1) enrolled adult patients undergoing musculoskeletal or orthopedic surgeries; (2) randomized them to any pharmacological or psychological interventions, or their combination directed at reducing CPSP, placebo, or usual care; and (3) assessed pain at 3 months or more after surgery. Screening for eligible trials, data extraction, and risk-of-bias assessment using revised Cochrane risk-of-bias tool (RoB 2.0) will be performed in duplicate and independently. Our main outcome of interest will be the proportion of surgical patients reporting any pain at ≥ 3 months after surgery. We will also collect data on other patient important outcomes, including pain severity, physical functioning, emotional functioning, dropout rate due to treatment-related adverse event, and overall dropout rate. We will perform a frequentist random-effects network meta-analysis to determine the relative treatment effects. When possible, the modifying effect of sex, surgery type and duration, anesthesia type, and veteran status on the effectiveness of interventions will be investigated using network meta-regression. We will use the GRADE approach to assess the certainty evidence and categorize interventions from most to least beneficial using GRADE minimally contextualised approach.

DISCUSSION

This network meta-analysis will assess the comparative effectiveness of pharmacological and psychological interventions directed at preventing CPSP after orthopedic surgery. Our findings will inform clinical decision-making and identify promising interventions for future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023432503.

[Opioid-free anesthesia : Wrong track or meaningful exit from the era of opioid-based analgesia?]

The limitations and disadvantages of opioids in anesthesia are very well known but the advantages combined with a lack of effective alternatives even now still prevents refraining from using opioids as part of an adequate pain therapy. For decades, pain research has had the declared goal of replacing opioids with new substances which have no serious side effects; however, currently this goal seems to be a long way off. Due to the media coverage of the "opioid crisis" in North America, the use of opioids for pain management is also increasingly being questioned by the patients. Measures to contain this crisis are only slowly taking effect in view of the increasing number of deaths, which is why the triggers are still being sought. The perioperative administration of opioids is not only a possible gateway to addiction and abuse but it can also cause outcome-relevant complications, such as respiratory depression, postoperative nausea and vomiting and an increase in postoperative pain. Therefore, these considerations gave rise to the idea of an opioid-free anesthesia (OFA), i.e., opioids are not administered as part of anesthesia to carry out surgical procedures. Although this idea may make sense at first glance, a rapid introduction of this concept appears to be risky as it entails significant changes for the entire anesthesiological management. Based on relatively robust data from clinical studies, this concept can now be evaluated and discussed not only emotionally but also objectively. This review article presents arguments for or against the complete avoidance of intraoperative or even perioperative opioids. The current conditions in Germany are primarily taken into account, so that the perioperative pain therapy is transferable to the established standards. The results from current clinical studies on the implementation of an opioid-free anesthesia are summarized and discussed.

Precision, integrative medicine for pain management in sickle cell disease

Sickle cell disease (SCD) is a prevalent and complex inherited pain disorder that can manifest as acute vaso-occlusive crises (VOC) and/or chronic pain. Despite their known risks, opioids are often prescribed routinely and indiscriminately in managing SCD pain, because it is so often severe and debilitating. Integrative medicine strategies, particularly non-opioid therapies, hold promise in safe and effective management of SCD pain. However, the lack of evidence-based methods for managing SCD pain hinders the widespread implementation of non-opioid therapies. In this review, we acknowledge that implementing personalized pain treatment strategies in SCD, which is a guideline-recommended strategy, is currently fraught with limitations. The full implementation of pharmacological and biobehavioral pain approaches targeting mechanistic pain pathways faces challenges due to limited knowledge and limited financial and personnel support. We recommend personalized medicine, pharmacogenomics, and integrative medicine as aspirational strategies for improving pain care in SCD. As an organizing model that is a comprehensive framework for classifying pain subphenotypes and mechanisms in SCD, and for guiding selection of specific strategies, we present evidence updating pain research pioneer Richard Melzack's neuromatrix theory of pain. We advocate for using the updated neuromatrix model to subphenotype individuals with SCD, to better select personalized multimodal treatment strategies, and to identify research gaps fruitful for exploration. We present a fairly complete list of currently used pharmacologic and non-pharmacologic SCD pain therapies, classified by their mechanism of action and by their hypothesized targets in the updated neuromatrix model.

Different Gabapentin and Pregabalin Dosages for Perioperative Pain Control in Patients Undergoing Spine Surgery: A Systematic Review and Network Meta-Analysis

IMPORTANCE

Patients undergoing spine surgery often experience severe pain. The optimal dosage of pregabalin and gabapentin for pain control and safety in these patients has not been well established.

OBJECTIVE

To evaluate the associations of pain, opioid consumption, and adverse events with different dosages of pregabalin and gabapentin in patients undergoing spine surgery.

DATA SOURCES

PubMed/MEDLINE, Embase, Web of Science, Cochrane library, and Scopus databases were searched for articles until August 7, 2021.

STUDY SELECTION

Randomized clinical trials conducted among patients who received pregabalin or gabapentin while undergoing spine surgery were included.

DATA EXTRACTION AND SYNTHESIS

Two investigators independently performed data extraction following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) reporting guideline. The network meta-analysis was conducted from August 2022 to February 2023 using a random-effects model.

MAIN OUTCOMES AND MEASURES

The primary outcome was pain intensity measured using the Visual Analog Scale (VAS), and secondary outcomes included opioid consumption and adverse events.

RESULTS

Twenty-seven randomized clinical trials with 1861 patients (median age, 45.99 years [range, 20.00-70.00 years]; 759 women [40.8%]) were included in the systematic review and network meta-analysis. Compared with placebo, the VAS pain score was lowest with gabapentin 900 mg per day, followed by gabapentin 1200 mg per day, gabapentin 600 mg per day, gabapentin 300 mg per day, pregabalin 300 mg per day, pregabalin 150 mg per day, and pregabalin 75 mg per day. Additionally, gabapentin 900 mg per day was found to be associated with the lowest opioid consumption among all dosages of gabapentin and pregabalin, with a mean difference of -22.07% (95% CI, -33.22% to -10.92%) for the surface under the cumulative ranking curve compared with placebo. There was no statistically significant difference in adverse events (nausea, vomiting, and dizziness) among all treatments. No substantial inconsistency between direct and indirect evidence was detected for all outcomes.

CONCLUSIONS AND RELEVANCE

These findings suggest that gabapentin 900 mg per day before spine surgery is associated with the lowest VAS pain score among all dosages. In addition, no differences in adverse events were noted among all treatments.

Sixth Annual Enhanced Recovery After Surgery Symposium highlights: work in progress or standard care?

Enhanced Recovery After Surgery (ERAS) protocols have demonstrated effectiveness in accelerating patient recovery and improving outcomes. Since the systemwide implementation of ERAS protocols at Baylor Scott & White Health, an annual multidisciplinary conference has provided a review of outcomes and advancements in the ERAS program. This meeting, coined the ERAS symposium, allows providers who utilize recovery protocols to collaborate with national and international leaders in the field to improve the clinical care of patients. The sixth annual ERAS symposium was held on February 10, 2023, and provided key presentations that discussed the latest results from ERAS efforts across multiple surgical specialties along with updates in anesthesia, nursing, and nutrition. A summary of those presentations, which included perioperative glycemic control, misconceptions in pain management, and emerging ERAS protocols in different surgical specialties, is provided to document the system progress.

Comparison of the effects of preoperative celecoxib and gabapentin on pain, functional recovery, and quality of life after total knee arthroplasty: A randomized controlled clinical trial

Background

Acute pain is one of the main complaints of patients after total knee arthroplasty (TKA), which causes delayed mobility, increased morphine consumption, and subsequently increased costs. Therefore, the present study was performed to evaluate the preventive effect of preoperative celecoxib and gabapentin on reducing patient pain as a primary outcome after TKA surgery.

Materials and Methods

This randomized, double-blind controlled clinical trial was performed on 270 patients with osteoarthritis that were candidates for TKA surgery allocated into three groups. In the first group, 900 mg of gabapentin was administered orally on a daily basis for 3 days before surgery. In the second group, 200 mg of oral celecoxib was administered twice daily for 3 days before surgery. In the third group, oral placebo was administered twice daily for 3 days before the surgery. The patients' pain score and knee and its functional score were recoded.

Results

The mean of reduction pain in gabapentin and celecoxib groups was significantly lower than that of the control group at 12, 24, and 48 h after surgery (P < 0.001); however, two groups were not significantly different from each other (P > 0.05). Furthermore, the two medication groups were not significantly different in this regard (P > 0.05). In addition, the knee score in the gabapentin group with the means of 85.40 ± 5.47 and the celecoxib group with the means of 87.03 ± 3.97 were significantly higher than those of the control group with the means of 78.90 ± 4.39 in the 1^st month after the surgery (P < 0.001).

Conclusion

According to the results of the present study, the preventive administration of gabapentin and celecoxib showed a significant and similar effectiveness on reducing patient pain after TKA surgery and on improving the KSS and quality of life scores.

Chronic pain after surgery and trauma: current situation and future directions

Chronic post-surgical pain (CPSP) stands as a major health issue. The unchanged incidence over the last two decades underlines both the failure of predictive models developed until now and the lack of efficacy of common “preventive” strategies (pharmacotherapy and regional analgesic techniques) applied in current clinical practice. The recognition of CPSP as a disease and the release of a common definition of the condition is an important progress in the field. CPSP predictive scores exist but none has presently demonstrated an impact on patient care. New clinical directions based on the resolution of postoperative pain, a complex and highly dynamic process supported by individual pain trajectories, argue for predictive models and preventive strategies extended to the subacute pain period i.e. after hospital discharge.

Perioperative parameters to consider for enhanced recovery in surgery (ERS) in gynecology (excluding breast surgery)

The current review explores the Enhanced Rehabilitation in Surgery (ERS) approach in the specific context of gynecological surgery. Implementation of an ERS protocol in gynecological surgery reduces postoperative complications and length of stay without increasing morbidity. An ERS approach is based on maintaining an adequate diet and hydration before the operation, according to the recommended time frame, to reduce the phenomenon of insulin resistance, and to optimize patient comfort. On the other hand, the use of anxiolytic treatment as premedication is not recommended. Systematic preoperative digestive preparation, a source of patient discomfort, is not associated with an improvement in the postoperative functional outcome or with a reduction in the rate of complications. A minimally invasive surgical approach is preferrable in the context of ERS. Prevention of surgical site infection includes measures such as optimized antibiotic prophylaxis, skin disinfection with alcoholic chlorhexidine, reduction in the use of drainage of the surgical site, and prevention of hypothermia. Early removal of the bladder catheter is associated with a reduction in the risk of urinary tract infection and a reduction in the length of hospital stay. Prevention of postoperative ileus is based on early refeeding, and prevention of postoperative nausea-vomiting in a multimodal strategy to be initiated during the intraoperative period. Intraoperative hydration should be aimed at achieving euvolemia. Pain control is based on a multimodal strategy to spare morphine use and may include locoregional analgesia. Medicines should be administered orally during the postoperative period to hasten the resumption of the patient's autonomy. The prevention of thromboembolic risk is based on a strategy combining drug prophylaxis, when indicated, and mechanical restraint, as well as early mobilization. However, the eclectic nature of the implementation of these measures as reported in the literature renders their interpretation difficult. Furthermore, beyond the application of one of these measures in isolation, the best benefit on the postoperative outcome is achieved by a combination of measures which then constitutes a global strategy allowing the objectives of the ERS to be met.

Quality of meta-analyses of non-opioid, pharmacological, perioperative interventions for chronic postsurgical pain: a systematic review

Background

In an attempt to aggregate observations from clinical trials, several meta-analyses have been published examining the effectiveness of systemic, non-opioid, pharmacological interventions to reduce the incidence of chronic postsurgical pain.

Objective

To inform the design and reporting of future studies, the purpose of our study was to examine the quality of these meta-analyses.

Evidence review

We conducted an electronic literature search in Embase, MEDLINE, and the Cochrane Database of Systematic Reviews. Published meta-analyses, from the years 2010 to 2020, examining the effect of perioperative, systemic, non-opioid pharmacological treatments on the incidence of chronic postsurgical pain in adult patients were identified. Data extraction focused on methodological details. Meta-analysis quality was assessed using the A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) critical appraisal tool.

Findings

Our search yielded 17 published studies conducting 58 meta-analyses for gabapentinoids (gabapentin and pregabalin), ketamine, lidocaine, non-steroidal anti-inflammatory drugs, and mexiletine. According to AMSTAR 2, 88.2% of studies (or 15/17) were low or critically low in quality. The most common critical element missing was an analysis of publication bias. Trends indicated an improvement in quality over time and association with journal impact factor.

Conclusions

With few individual trials adequately powered to detect treatment effects, meta-analyses play a crucial role in informing the perioperative management of chronic postsurgical pain. In light of this inherent value and despite a number of attempts, high-quality meta-analyses are still needed.

PROSPERO registration number

CRD42021230941.

Avoid Postoperative Pain To Prevent Its Chronification: A Narrative Review

Acute postoperative pain is a normal and expected part of the patient’s postsurgical trajectory, and its intensity, severity, and duration vary with surgery-related and patient factors. In a subset of patients, postoperative pain does not resolve as the tissue heals but instead transitions to chronic postoperative pain, a challenging condition to treat and one associated with decreased quality of life, sleep and mood disorders, and neuropathy. Promptly and adequately treating acute postoperative pain can reduce the risk that it will transition into chronic postoperative pain. Numerous agents are available that may help treat postoperative pain, including nonsteroidal anti-inflammatory drugs, opioids, antidepressants, anticonvulsants, and others. In this connection, it is also important to consider patient factors, such as mental health status and comorbidities, as well as the type and duration of surgery. A multimodal approach is recommended, which uses two or more agents with complementary mechanisms of action, working at different targets. Multimodal analgesia may also reduce adverse events and lessen opioid consumption after surgery. A particularly useful fixed-dose combination product is dexketoprofen/tramadol (DEX-TRA), which is safe and effective in numerous clinical trials. This review is based on a presentation from the Roma Pain Days scientific sessions of 2021.

Effects of Gabapentin Enacarbil on Postoperative Pain After Hip and Knee Arthroplasty: A Placebo-controlled Randomized Trial

OBJECTIVES

Total joint arthroplasties are among the most common elective procedures performed in the United States, and they are associated with postoperative pain. Gabapentin enacarbil is a prodrug with an extended-release formulation that has been proposed for multimodal postoperative analgesia, but the drug's efficacy for major arthroplasties remains unclear.

MATERIALS AND METHODS

We enrolled 60 adult patients scheduled for primary knee or hip arthroplasty expected to remain hospitalized for at least 3 days. Eligible patients were randomly assigned to placebo or gabapentin enacarbil 600 mg twice daily starting the day before surgery continuing for 3 days thereafter.The primary outcome was analyzed using a joint hypothesis framework of pain (0 to 10 verbal response scores) and cumulative opioid consumption (mg of morphine equivalent) within the first 72 hours. Secondary outcomes were nausea and vomiting, pain persisting 90 days after surgery, duration of hospitalization, and early postoperative health status using quality of recovery score (QoR-15).

RESULTS

Twenty-eight patient in gabapentin enacarbil group and 32 in placebo group were analyzed. Since pain scores did not differ significantly (difference of means: -0.2 in pain scores; 95% confidence interval: -1.1, 0.7), nor did opioid consumption, conditions for joint hypothesis testing were not met. Moreover, there were no significant differences between groups for secondary outcomes.

DISCUSSION

We did not identify statistically significant or clinically meaningful differences in our primary and secondary outcomes related to perioperative use of gabapentin enacarbil in patients having primary hip or knee arthroplasties.

Pregabalin vs placebo to prevent chronic pain after whiplash injury in at-risk individuals: results of a feasibility study for a large randomised controlled trial

ABSTRACT

There are few effective treatments for acute whiplash-associated disorders (WADs). Early features of central sensitisation predict poor recovery. The effect of pregabalin on central sensitisation might prevent chronic pain after acute whiplash injury. This double blind, placebo-controlled randomised controlled trial examined feasibility and potential effectiveness of pregabalin compared with placebo for people with acute WAD. Twenty-four participants with acute WAD (<48 hours) and at risk of poor recovery (pain ≥5/10) were recruited from hospital emergency departments in Queensland, Australia, and randomly assigned by concealed allocation to either pregabalin (n = 10) or placebo (n = 14). Pregabalin was commenced at 75 mg bd, titrated to 300 mg bd for 4 weeks, and then weaned over 1 week. Participants were assessed at 5 weeks and 3, 6, and 12 months. Feasibility issues included recruitment difficulties and greater attrition in the placebo group. For the primary clinical outcome of neck pain intensity, attrition at 5 weeks was pregabalin: 10% and placebo: 36% and at 12 months was pregabalin: 10% and placebo: 43%. Pregabalin may be more effective than placebo for the primary clinical outcome of neck pain intensity at 3 months (mean difference: -4.0 [95% confidence interval -6.2 to -1.7]) on an 11-point Numerical Rating Scale. Effects were maintained at 6 months but not 12 months. There were no serious adverse events. Minor adverse events were more common in the pregabalin group. A definitive large randomised controlled trial of pregabalin for acute whiplash injury is warranted. Feasibility issues would need to be addressed with modifications to the protocol.

Association Between Gabapentinoids and Postoperative Pulmonary Complications in Patients Undergoing Thoracic Surgery

OBJECTIVE

Perioperative gabapentinoids in general surgery have been associated with an increased risk of postoperative pulmonary complications (PPCs), while resulting in equivocal pain relief. This study's aim was to examine the utilization of gabapentinoids in thoracic surgery to determine the association of gabapentinoids with PPCs and perioperative opioid utilization.

DESIGN

A multicenter retrospective cohort study.

SETTING

Hospitals in the Premier Healthcare Database from 2012 to 2018.

PARTICIPANTS

A total of 70,336 patients undergoing elective open thoracotomy, video-assisted thoracic surgery, and robotic-assisted thoracic surgery.

INTERVENTIONS

Propensity score analyses were used to assess the association between gabapentinoids on day of surgery and the primary composite outcome of PPCs, defined as respiratory failure, pneumonia, reintubation, pulmonary edema, and noninvasive and invasive ventilation. Secondary outcomes included invasive and noninvasive ventilation, hospital mortality, length of stay, opioid consumption on day of surgery, and average daily opioid consumption after day of surgery.

RESULTS

Overall, 8,142 (12%) patients received gabapentinoids. The prevalence of gabapentin on day of surgery increased from 3.8% in 2012 to 15.9% in 2018. Use of gabapentinoids on day of surgery was associated with greater odds of PPCs (odds ratio [OR] 1.19, 95% CI 1.11-1.28), noninvasive mechanical ventilation (OR 1.30, 95% CI 1.16-1.45), and invasive mechanical ventilation (OR 1.14, 95% CI 1.02-1.28). Secondary outcomes indicated no clinically meaningful associations of gabapentinoid use with opioid consumption, hospital mortality, or length of stay.

CONCLUSIONS

Perioperative gabapentinoid administration in elective thoracic surgery may be associated with a higher risk of PPCs and no opioid-sparing effect.

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

Chinese Association for the Study of Pain: Expert consensus on chronic postsurgical pain

Chronic postsurgical pain is a common surgical complication that severely reduces a patient’s quality of life. Many perioperative interventions and management strategies have been developed for reducing and managing chronic postsurgical pain. Under the leadership of the Chinese Association for the Study of Pain, an editorial committee was formed for chronic postsurgical pain diagnosis and treatment by experts in relevant fields. The editorial committee composed the main content and framework of this consensus and established a working group. The working group conducted literature review (1989-2020) using key words such as “surgery”, “post-surgical”, “post-operative”, “pain”, “chronic”, and “persistent” in different databases including MEDLINE, EMBASE, PubMed, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews. Only publications in the English language were included. The types of literature included systematic reviews, randomized controlled studies, cohort studies and case reports. This consensus was written based on clinical practice combined with literature evidence. The first draft of the consensus was rigorously reviewed and edited by all the editorial committee experts before being finalized. The level of evidence was assessed by methodological experts based on the Oxford Centre for Evidence-Based Medicine Levels of Evidence. The strength of recommendation was evaluated by all editorial committee experts, and the opinions of most experts were adopted as the final decision. The recommendation level “strong” generally refers to recommendations based on high-level evidence and consistency between clinical behavior and expected results. The recommendation level “weak” generally refers to the uncertainty between clinical behavior and expected results based on low-level evidence.

Prolonged encephalopathy and associated nonconvulsive seizures from suspected pregabalin and tapentadol: Two case reports and review of literature

A combination of pregabalin and tapentadol may be associated with prolonged encephalopathy.

Challenges and opportunities in translational pain research - An opinion paper of the working group on translational pain research of the European pain federation (EFIC)

For decades, basic research on the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need. In this opinion paper bringing together pain researchers from very different disciplines, the opportunities and challenges of translational pain research are discussed. The many factors that may prevent the successful translation of bench observations into useful and effective clinical applications are reviewed, including interspecies differences, limited validity of currently available preclinical disease models of pain, and limitations of currently used methods to assess nociception and pain in non-human and human models of pain. Many paths are explored to address these issues, including the backward translation of observations made in patients and human volunteers into new disease models that are more clinically relevant, improved generalization by taking into account age and sex differences, and the integration of psychobiology into translational pain research. Finally, it is argued that preclinical and clinical stages of developing new treatments for pain can be improved by better preclinical models of pathological pain conditions alongside revised methods to assess treatment-induced effects on nociception in human and non-human animals. Significance: For decades, basic research of the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need.

[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.

The role of regional anaesthesia and multimodal analgesia in the prevention of chronic postoperative pain: a narrative review

Effective prevention of chronic postoperative pain is an important clinical goal, informed by a growing body of studies. Peri-operative regional anaesthesia remains one of the most important tools in the multimodal analgesic toolbox, blocking injury-induced activation and sensitisation of both the peripheral and central nervous system. We review the definition and taxonomy of chronic postoperative pain, its mechanistic basis and the most recent evidence for the preventative potential of multimodal analgesia, with a special focus on regional anaesthesia. While regional anaesthesia targets several important aspects of the mechanistic pathway leading to chronic postoperative pain, evidence for its efficacy is still mixed, possibly owing to the heterogeneity of risk profiles within the surgical patient, but also to variation in techniques and medications reported in the literature.

Perioperative Pregabalin for Preventive Analgesia in Breast Cancer Surgery: A Meta-analysis of Randomized Controlled Trials

OBJECTIVES

Pregabalin is a drug for neuropathic pain. Antipronociceptive properties of pregabalin have led to its recent use as an adjuvant to the multimodal postoperative pain regimen. This meta-analysis was conducted to evaluate the efficacy of perioperative pregabalin on acute and chronic postsurgical pain (CPSP) after breast cancer surgery.

METHODS

A meta-analysis including 8 randomized controlled trials searched from MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials was conducted. Subgroup analysis was performed according to doses and timecourse of pregabalin administration. Review Manager 5.3 was selected to conduct the meta-analysis.

RESULTS

Preoperative pregabalin in breast cancer surgery alleviated acute postoperative pain at rest 24 hours after surgery by 0.31 points on an 0 to 10 Numerical Rating Scale (95% confidence interval [CI] -0.57 to -0.05). Morphine consumption showed a decrease in postoperative use by 1.09 mg (95% CI: -1.61 to -0.57). The incidence of CPSP 3 months after surgery was reduced to 46% (95% CI: 0.25-0.85). Postoperative nausea and vomiting, dizziness, and sedation showed no overall significant reductions. However, a decrease in the incidence of postoperative nausea and vomiting and an increase in the incidence of dizziness were noted when patients received 300 mg of pregabalin before surgery.

DISCUSSION

This study demonstrated that pregabalin showed more efficacy on chronic pain than acute pain after a breast cancer surgery. Further study based on doses and treatment course of pregabalin should be conducted to establish stronger evidence of treatment effects.

Chronic Pain Following Cosmetic Breast Surgery: A Comprehensive Review

INTRODUCTION

Cosmetic breast surgery is commonly performed in the United States; 520,000 procedures of the total 1.8 million cosmetic surgical procedures performed in 2018 were breast related. Postoperative chronic pain, defined as lasting 3 or more months, has been reported in a wide variety of breast surgical procedures including breast augmentation, reduction mammaplasty, mastectomy, and mastectomy with reconstruction. Patient characteristics associated with the development of postoperative chronic pain following cosmetic breast surgery include a younger age, larger BMI, smaller height, postoperative hyperesthesia, and elevated baseline depression, anxiety, and catastrophizing scores. The anatomical distribution of chronic pain following breast augmentation procedures is dependent upon incision site placement; pectoral and intercostal nerves have been implicated. The purpose of this review is to provide an update on the current literature addressing the pathophysiology, clinical presentation, and treatment of patients presenting with chronic postoperative pain following cosmetic breast surgery.

METHODS

A comprehensive literature review was performed in MEDLINE, PubMed, and Cochrane databases from 1996 to 2019 using the terms "cosmetic surgery", "breast surgery", "postoperative pain", and "chronic pain".

RESULTS

Cosmetic breast surgery can have a similar presentation as post-mastectomy pain syndrome and thus have overlapping diagnostic criteria. Seven domains are identified for a diagnosis of PBSPS: Pain after breast surgery, neuropathic in nature, at least a moderate intensity of pain, as defined as within the middle one-third of the selected pain scale, pain for at least 6 months, symptoms occurring for 12 or more hours a day for a minimum of 4 days each week, pain in at least one of the following sites: breast, chest wall, axilla, or arm on the affected side, pain exacerbated by movement. Patient risk factors and surgical risk factors may influence the development of chronic post-cosmetic surgery breast pain. Improved perioperative analgesia including preoperative regional nerve anesthesia and postoperative catheter infusion have been shown to improve chronic postoperative pain outcomes.

CONCLUSIONS

The present review provides a discussion of clinical presentation, pathophysiology, and treatment and preventative strategies for chronic breast pain following cosmetic surgery. This review provides evidence from multiple randomized controlled trials (RCTs) and systematic reviews of efficacy and effectiveness. While chronic postoperative breast pain remains challenging to treat, various preventative strategies have been described to improve postoperative pain outcomes.

Pain measurement and critical review of analgesic trials: pain scores, functional pain measurements, limits and bias of clinical trials

Randomized clinical trials designed to assess analgesic agents and/or techniques used for postoperative pain control have several limitations, which are addressed in this article. Efficacy of analgesics cannot be limited to the evaluation of pain intensity or the amount of opioid rescue medication, but it also means to evaluate parameters such as the delay and duration of the effect, the number of patients with satisfactory pain control, and side effects. Because combination of analgesics is the standard of care in clinical practice, its value also needs to be documented. Eventually, analgesic treatments have to be considered in the settings of postoperative supportive care and enhanced recovery programmes after surgery.

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.

Short- and long-term impact of remifentanil on thermal detection and pain thresholds after cardiac surgery: A randomised controlled trial

BACKGROUND

The clinical relevance of the suggested hyperalgesic effects of remifentanil is still unclear, especially in the long term.

OBJECTIVE

The current study evaluated the impact of remifentanil on thermal thresholds 3 days and 12 months after surgery, measured with Quantitative Sensory Testing.

DESIGN

A single-blind, randomised controlled trial.

SETTING

A tertiary care teaching hospital in The Netherlands, from 2014 to 2016.

PATIENTS

A total of 126 patients aged between 18 and 85 years, undergoing cardiothoracic surgery via sternotomy (coronary artery bypass grafts and/or valve replacement) were included. Exclusion criteria were BMI above 35 kg m, history of cardiac surgery, chronic pain conditions, neurological conditions, allergy to opioids or paracetamol, language barrier and pregnancy.

INTERVENTIONS

Patients were allocated randomly to receive intra-operatively either a continuous remifentanil infusion or intermittent intra-operative fentanyl as needed in addition to standardised anaesthesia with propofol and intermittent intravenous fentanyl at predetermined time points.

MAIN OUTCOME MEASURES

Warm and cold detection and pain thresholds 3 days and 12 months after surgery. In addition the use of remifentanil, presence of postoperative chronic pain, age, opioid consumption and pre-operative quality of life were tested as a predictor for altered pain sensitivity 12 months after surgery.

RESULTS

Both warm and cold detection, and pain thresholds, were not significantly different between the remifentanil and fentanyl groups 3 days and 12 months after surgery (P > 0.05). No significant predictors for altered pain sensitivity were identified.

CONCLUSION

Earlier reports of increased pain sensitivity 1 year after the use of remifentanil could not be confirmed in this randomised study using Quantitative Sensory Testing. This indicates that remifentanil plays a minor role in the development of chronic thoracic pain. Still, the relatively high incidence of chronic thoracic pain and its accompanying impact on quality of life remain challenging problems.

TRIAL REGISTRATION

The study was registered at EudraCT (ref: 2013-000201-23) and ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT02031016).

The influence of pre- and perioperative administration of gabapentin on pain 3-4 years after total knee arthroplasty

BACKGROUND AND AIMS

Approximately 20% of patients having total knee arthroplasty (TKA) will experience chronic postoperative pain. Recently, preoperative pain facilitation has been associated with chronic pain after TKA, and gabapentin has been shown to decrease pain facilitation. The current study is a secondary follow-up of a primary RCT investigating the effect of gabapentin on acute postoperative pain after TKA and exploring the effect of pre- and perioperative administration of gabapentin on chronic postoperative pain and psychological state 3-4 years after TKA.

METHODS

Patients scheduled for TKA were randomized to either gabapentin 1,300 mg/day, gabapentin 900 mg/day, or placebo daily from 2-h before and 6 days after operation. Pre- and 3-4 years postoperatively pain scores related to pain while walking, at rest, when flexing the hip or the knee were collected. At the same time, the pain catastrophizing scale (PCS) and hospital anxiety and depression scale subscales for anxiety (HADS-A) and depression (HADS-D) were collected.

RESULTS

Lower postoperative pain while walking, flexing the hip, and at rest were found compared with preoperative scores (p<0.03), but these were not associated with gabapentin treatment (p>0.19). Significantly lower postoperative PCS and HADS-A scores were seen compared with preoperative scores (p<0.001), but these were not associated with gabapentin treatment (p>0.55).

CONCLUSIONS

The current study found that pre- and perioperative administrations of gabapentin do not influence the pain or psychological state 3-4 years after TKA.

IMPLICATIONS

The current study does not support that short-term pre- and perioperative use of gabapentin can reduce the development of chronic postoperative pain after TKA.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

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

The efficacy of pregabalin for the management of acute and chronic postoperative pain in thoracotomy: a meta-analysis with trial sequential analysis of randomized-controlled trials

PURPOSE

Pregabalin is commonly used as an analgesic for neuropathic pain. But pregabalin as an adjunct to a multimodal analgesic regimen - although standard clinical protocol in some settings - has remained controversial. This meta-analysis was conducted to identify the efficacy of pregabalin for management of postoperative pain in thoracotomy.

MATERIALS AND METHODS

Pubmed, Embase, Cochrane, Web of Science, Springer, and Clinical Trial Register database were searched for randomized controlled trials (RCTs) of pregabalin in preventing postoperative pain in thoracotomy. Review Manager 5.3 and STATA 12.0 were selected to conduct the meta-analysis. Trial sequential analysis was used to control random errors and calculate the required information size.

RESULTS

Nine RCTs with 684 patients were included in our meta-analysis. Outcomes favoring pregabalin included less pain on a 0-10 scale on 1 day [mean difference (MD): -0.87; 95% CI: -1.55 to -0.19; P=0.01], 3 days (MD: -1.55; 95% CI: -1.93 to -1.18; P<0.00001), 1 month (MD: -1.58; 95% CI: -2.75 to -0.42; P=0.008), 3 months (MD: -1.69; 95% CI: -2.71 to -0.66; P=0.001) postoperatively, and less incidence of neuropathic pain (OR: 0.20; 95% CI: 0.05-0.91; P=0.04), less mean morphine consumption (MD: -5.03; 95% CI: -8.06 to -1.99; P=0.001), but more dizziness (OR: 3.33; 95% CI: 1.36-8.17; P=0.009), more drowsiness (OR: 8.61; 95% CI: 2.23-33.20; P=0.002), and less constipation (OR: 0.23; 95% CI: 0.09-0.59; P=0.002). There was no statistical differences in pain score on 7 days (MD:-0.77; 95% CI: -2.38 to 0.84; P=0.35), nausea (OR: 0.73; 95% CI: 0.42-1.26; P=0.26), and vomiting (OR: 0.83; 95% CI: 0.36-1.90; P=0.65).

CONCLUSION

Pregabalin can prevent postoperative pain in thoracotomy and decrease incidence of neuropathic pain and morphine consumption. Pregabalin may be a valuable asset in management of acute and persistent postoperative pain in thoracotomy.

Chronic postsurgical pain: current evidence for prevention and management

Chronic postsurgical pain (CPSP) is an unwanted adverse event in any operation. It leads to functional limitations and psychological trauma for patients, and leaves the operative team with feelings of failure and humiliation. Therefore, it is crucial that preventive strategies for CPSP are considered in high-risk operations. Various techniques have been implemented to reduce the risk with variable success. Identifying the risk factors for each patient and applying a timely preventive strategy may help patients avoid the distress of chronic pain. The preventive strategies include modification of the surgical technique, good pain control throughout the perioperative period, and preoperative psychological intervention focusing on the psychosocial and cognitive risk factors. Appropriate management of CPSP patients is also necessary to reduce their suffering. CPSP usually has a neuropathic pain component; therefore, the current recommendations are based on data on chronic neuropathic pain. Hence, voltage-dependent calcium channel antagonists, antidepressants, topical lidocaine and topical capsaicin are the main pharmacological treatments. Paracetamol, NSAIDs and weak opioids can be used according to symptom severity, but strong opioids should be used with great caution and are not recommended. Other drugs that may be helpful are ketamine, clonidine, and intravenous lidocaine infusion. For patients with failed pharmacological treatment, consideration should be given to pain interventions; examples include transcutaneous electrical nerve stimulation, botulinum toxin injections, pulsed radiofrequency, nerve blocks, nerve ablation, neuromodulation and surgical management. Physical therapy, cognitive behavioral therapy and lifestyle modifications are also useful for relieving the pain and distress experienced by CPSP patients.

Persistent Post-Mastectomy Pain: Risk Factors and Current Approaches to Treatment

Persistent Post-Mastectomy Pain (PPMP) is a common condition that can follow surgeries for breast cancer, the most common cancer in women. Because of the frequency of PPMP and its potential severity, it has received increasing research attention. This manuscript reviews the recent research literature, beginning with a brief history and then relevant medical, surgical, demographic, and psychosocial risk factors. Subsequently, social, psychological, and functional sequelae that have been linked to PPMPS are considered, as is research on current pharmacological, psychological, and rehabilitative approaches to treatment. The review concludes with a discussion of directions for future research and treatment that might reduce the incidence and impact of PPMP on breast cancer survivors. PERSPECTIVE: This article describes current research literature involving mechanisms, risks, and treatments related to persistent post-mastectomy pain. Implications of research findings also are discussed for pre- and post-surgical approaches to pain management, current treatments, and promising research directions.

Injury-induced maladaptation and dysregulation of calcium channel α2 δ subunit proteins and its contribution to neuropathic pain development

Voltage-gated calcium channels (VGCCs) play important roles in physiological functions including the modulation of neurotransmitter release, neuronal network activities, intracellular signalling pathways and gene expression. Some pathological conditions, including nerve injuries, can cause the dysregulation of VGCCs and their subunits. This in turn can lead to a functional maladaptation of VGCCs and their subunits, which can contribute to the development of disorders such as pain sensations. This review has summarized recent findings related to maladaptive changes in the dysregulated VGCC α2 δ1 subunit (Cav α2 δ1 ) with a focus on exploring the mechanisms underlying the contribution of Cav α2 δ1 to pain signal transduction. At least under neuropathic pain conditions, the dysregulated Cav α2 δ1 can modulate VGCC functions as well as other plasticity changes. The latter includes abnormal excitatory synaptogenesis resulting from its interactions with injury-induced extracellular matrix glycoprotein molecule thrombospondins, which is independent of the VGCC functions. Blocking Cav α2 δ1 with gabapentinoids can reverse neuropathic pain significantly with relatively mild side effects, but only in a small population of neuropathic pain patients due to reasons yet to be explored. There are emerging data suggesting that early preventive treatment with gabapentinoids can prevent aberrant excitatory synapse formation and the development of chronic pain. If these findings are confirmed clinically, this could be an attractive approach for neuropathic pain management.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

New Advances in Acute Postoperative Pain Management

PURPOSE OF REVIEW

Postoperative pain remains one of the most common challenges following inpatient and outpatient surgeries. With our advances in modern medicine, pain following surgical procedures still remains a challenge, though significant accomplishments have been made over the past few decades. This article highlights some of the promising new advances and approaches in postoperative pain management.

RECENT FINDINGS

Over the last decade, Enhanced Recovery after Surgery (ERAS) pathways and protocols are becoming the benchmark standards for enhancing postoperative recovery. Multimodal analgesia (MMA) is an essential component of such care. Further, in the wake of serious and persistent concern on the opioid epidemic in the USA, there has been a recent renewal of interest in non-opioid alternatives or adjuncts in controlling postoperative pain, often in the context of MMA. Intravenous (IV) acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), magnesium, ketamine, dexmedetomidine, liposomal bupivacaine, and newer neuraxial and peripheral regional techniques as well as patient-controlled modalities are gaining importance. Gabapentinoids have become popular but recent meta-analytic reviews have cast doubt on their routine use in perioperative settings. Among opioids, sublingual sufentanil, IV oxycodone, and iontophoretic transdermal fentanyl hold promise. Acupuncture and transcutaneous electrical nerve stimulation may be useful as adjuncts in MMA packages. Genetic testing, derivatives of herbal preparations, and an extended role of acute pain services may emerge as potential areas of importance in the future. There are, however, critical gaps in good quality evidence in many of the practice guideline recommendations. In the era of opioid epidemic, several lines of evidence have emerged to support non-opioid-based drugs and approaches along with a few newer opioid formulations for postoperative pain management, although more research is needed to find the right balance of efficacy and safety.

Is there a reasonable excuse for not providing post-operative analgesia when using animal models of peripheral neuropathic pain for research purposes?

Introduction

The induction of neuropathic pain-like behaviors in rodents often requires surgical intervention. This engages acute nociceptive signaling events that contribute to pain and stress post-operatively that from a welfare perspective demands peri-operative analgesic treatment. However, a large number of researchers avoid providing such care based largely on anecdotal opinions that it might interfere with model pathophysiology in the longer term.

Objectives

To investigate effects of various peri-operative analgesic regimens encapsulating different mechanisms and duration of action, on the development of post-operative stress/welfare and pain-like behaviors in the Spared Nerve Injury (SNI)-model of neuropathic pain.

Methods

Starting on the day of surgery, male Sprague-Dawley rats were administered either vehicle (s.c.), carprofen (5.0mg/kg, s.c.), buprenorphine (0.1mg/kg s.c. or 1.0mg/kg p.o. in Nutella^®), lidocaine/bupivacaine mixture (local irrigation) or a combination of all analgesics, with coverage from a single administration, and up to 72 hours. Post-operative stress and recovery were assessed using welfare parameters, bodyweight, food-consumption, and fecal corticosterone, and hindpaw mechanical allodynia was tested for assessing development of neuropathic pain for 28 days.

Results

None of the analgesic regimes compromised the development of mechanical allodynia. Unexpectedly, the combined treatment with 0.1mg/kg s.c. buprenorphine and carprofen for 72 hours and local irrigation with lidocaine/bupivacaine, caused severe adverse effects with peritonitis. This was not observed when the combination included a lower dose of buprenorphine (0.05mg/kg, s.c.), or when buprenorphine was administered alone (0.1mg/kg s.c. or 1.0mg/kg p.o.) for 72 hours. An elevated rate of wound dehiscence was observed especially in the combined treatment groups, underlining the need for balanced analgesia. Repeated buprenorphine injections had positive effects on body weight the first day after surgery, but depressive effects on food intake and body weight later during the first week.

Conclusion

Post-operative analgesia does not appear to affect established neuropathic hypersensitivity outcome in the SNI model.

Pregabalin reduces opioid consumption and hyperalgesia but not pain intensity after laparoscopic donor nephrectomy

BACKGROUND

Gabapentinoids are increasingly used to reduce acute postoperative pain, opioid consumption and opioid-related adverse effects. We explored the opioid-sparing, analgesic and anti-hyperalgesic effect of perioperative administered pregabalin in laparoscopic living donor nephrectomy.

METHODS

In this randomized controlled trial, 80 patients were recruited and randomized to receive pregabalin 150 mg twice daily or placebo on the day of surgery and the first postoperative day as part of a multimodal analgesic regimen. Primary outcome was opioid consumption 0-48 h after surgery. Secondary outcomes were pain intensity at rest and with movement 0-48 h after surgery using the 0-10 Numeric Rating Scale and incisional hyperalgesia measured 24 h post-surgery and at hospital discharge. Further secondary outcomes were adverse effects. Persistent post-surgical pain was registered 6 weeks, 6 and 12 months after surgery.

RESULTS

Pregabalin significantly reduced opioid consumption compared with placebo 0-48 h after surgery (median mg [25th, 75th percentile]); 29.0 (22.0-45.5) vs. 41.8 (25.8-63.6) (P = 0.04). Pain intensity 0-48 h after surgery calculated as area under the pain (NRS) vs. time curve was not statistically different between groups at rest (P = 0.12) or with movement (P = 0.21). Pregabalin decreased incisional hyperalgesia 24 h after surgery (median cm [25th, 75th percentile] 8.5 (1.0-18.5) vs. 15.5 (9.5-24.0) (P = 0.02). Nausea (P ≤ 0.01), use of antiemetics (P ≤ 0.01) and pain-related sleep interference (P = 0.02) were reduced with pregabalin.

CONCLUSIONS

Perioperative pregabalin added to a multimodal analgesic regimen was opioid-sparing, but made no difference to pain intensity score 0-48 h after surgery. Pregabalin may reduce incisional hyperalgesia on the first day after surgery.

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

Identifying operations and individuals with an increased risk of chronic postsurgical pain (CPSP) has led to significant interest in interventions with the potential to achieve primary prevention of this condition. Pharmacological prevention remains controversial with a Cochrane review identifying perioperative ketamine administration as the only intervention with possible benefit although, with only small, heterogeneous studies, the authors called for a large randomised controlled trial (RCT) to confirm the validity of this result. In response to these data, a group of researchers from Australia and Hong Kong designed the ROCKet trial - Reduction Of Chronic Post-surgical Pain with Ketamine, endorsed by the Australian and New Zealand College of Anaesthetists (ANZCA) Clinical Trials Network (CTN).

Neuropathic pain treatment and research: experiences from the United Kingdom mission to Afghanistan and future prospects

The Defence Medical Services (DMS) of the United Kingdom (UK) assumed command of the Role 3 Medical Treatment Facility field hospital during Operation HERRICK in Afghanistan from April 2006 until the final drawdown in November 2014. The signature injury sustained by coalition personnel during this period was traumatic amputation from improvised explosive devices. Many patients who had suffered extensive tissue damage experienced both nociceptive and neuropathic pain (NeuP). This presented as a heterogeneous collection of symptoms that are resistant to treatment. This paper discusses the relationship of NeuP in the context of ballistic injury, drawing in particular on clinical experience from the UK mission to Afghanistan, Operation HERRICK. The role of this paper is to describe the difficulties of assessment, treatment and research of NeuP and make recommendations for future progress within the DMS.

Chronic postoperative pain: recent findings in understanding and management

Chronic postoperative pain is a poorly recognized potential outcome from surgery. It affects millions of patients every year, with pain lasting for months to years, resulting in patient suffering and ensuing economic consequences. The operations with the highest incidence of chronic postoperative pain are amputations, thoracotomies, cardiac surgery, and breast surgery. Other risk factors include preoperative pain, psychological factors, demographics, and the intensity of acute postoperative pain. Attempts to prevent chronic postoperative pain have often led to debatable results. This article presents data from recently published studies examining the incidence, risk factors, mechanisms, treatment options, and preventive strategies for chronic postoperative pain in adults. In summary, many of the previously identified risk factors for chronic postoperative pain have been confirmed and some novel ones discovered, such as the importance of the trajectory of acute pain and the fact that catastrophizing may not always be predictive. The incidence of chronic postoperative pain hasn’t changed over time, and there is limited new information regarding an effective preventive therapy. For example, pregabalin may actually cause more harm in certain surgeries. Further research is needed to demonstrate whether multimodal analgesic techniques have the best chance of significantly reducing the incidence of chronic postoperative pain and to determine which combination of agents is best for given surgical types and different patient populations.