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

Perioperative pain management for cardiac surgery

PURPOSE OF REVIEW

Acute postsurgical pain after cardiac surgery is challenging to treat. Adverse effects related to the high dose opioids which have traditionally been used perioperatively in cardiac surgery have led to the adoption of alternative analgesic strategies. This review aims to highlight current evidence-based approaches to managing pain after cardiac surgery.

RECENT FINDINGS

Current evidence and international guidelines support the use of multimodal analgesics for managing perioperative pain after cardiac surgery. Regional anaesthesia in the form of fascial plane blocks, such as the erector spinae plane and parasternal intercostal plane blocks, are effective and safe techniques for anticoagulated cardiac surgery patients. Transitional pain services are multidisciplinary programmes that bridge the gap between inpatient and outpatient care for these patients.

SUMMARY

This paper reviews advancements in perioperative pain management for cardiac surgery patients, emphasising the shift from high-dose opioids to multimodal analgesia and regional anaesthetic techniques, and highlighting the role of multidisciplinary transitional pain services.

Presurgical anxiety and acute postsurgical pain predict worse chronic pain profiles after total knee/hip arthroplasty

INTRODUCTION

Total joint arthroplasties generally achieve good outcomes, but chronic pain and disability are a significant burden after these interventions. Acknowledging relevant risk factors can inform preventive strategies. This study aimed to identify chronic pain profiles 6 months after arthroplasty using the ICD-11 (International Classification of Diseases) classification and to find pre and postsurgical predictors of these profiles.

MATERIALS AND METHODS

Patients undergoing total knee/hip arthroplasty (n = 209, female = 54.5%) were assessed before surgery, 48 h and 6 months postsurgery for sociodemographic, pain-related, disability and psychological characteristics. K-means-constrained cluster analysis identified chronic pain profiles based on 6-month pain intensity, pain interference and disability. Chi-square tests or one-way ANOVA explored between-cluster differences. Multinomial regression identified predictors of cluster membership. Separate models analyzed presurgical (model 1), postsurgical (model 2) and a combination of previously significant pre and postsurgical (model 3) variables.

RESULTS

A three-cluster solution was selected, translating increasingly worse chronic pain severity: cluster 1 (C1, n = 129), cluster 2 (C2, n = 60) and cluster 3 (C3, n = 20). There were presurgical differences among clusters in the presence of other painful sites (p = 0.013, ϕc = 0.20), pain interference (p = 0.038, η2 = 0.031), disability (p = 0.020, η2 = 0.037), pain catastrophizing (p = 0.019, η2 = 0.060), anxiety (p < 0.001, η2 = 0.087), depression (p = 0.017; η2 = 0.039), self-efficacy (p = 0.018, η2 = 0.038) and satisfaction with life (p = 0.034, η2 = 0.032), postsurgical pain frequency (p = 0.003, ϕc = 0.243) and intensity (p < 0.001, η2 = 0.101). In model 1, disability predicted C2 (OR = 1.040) and anxiety predicted C3 (OR = 1.154) membership. In model 2, pain intensity predicted C3 (OR = 1.690) membership. In model 3, presurgical anxiety predicted C3 (OR = 1.181) and postsurgical pain intensity predicted C2 (OR = 1.234) and C3 (OR = 1.679) membership.

CONCLUSIONS

Most patients had low chronic pain severity at 6 months, but a relevant percentage exhibited poor outcomes. Membership to different outcome profiles was predicted by presurgical anxiety and acute postsurgical pain. These seem promising targets to prevent pain chronification that should be optimized for better surgical outcomes.

Blood proteomics and multimodal risk profiling of human volunteers after incision injury: A translational study for advancing personalized pain management after surgery

A significant number of patients develop chronic pain after surgery, but prediction of those who are at risk is currently not possible. Thus, prognostic prediction models that include bio-psycho-social and physiological factors in line with the complex nature of chronic pain would be urgently required. Here, we performed a translational study in male volunteers before and after an experimental incision injury. We determined multi-modal features ranging from pain characteristics and psychological questionnaires to blood plasma proteomics. Outcome measures included pain intensity ratings and the extent of the area of hyperalgesia to mechanical stimuli surrounding the incision, as a proxy of central sensitization. A multi-step logistic regression analysis was performed to predict outcome measures based on feature combinations using data-driven cross-validation and prognostic model development. Phenotype-based stratification resulted in the identification of low and high responders for both outcome measures. Regression analysis revealed prognostic proteomic, specific psychophysical, and psychological features. A combinatorial set of distinct features enabled us to predict outcome measures with increased accuracy compared to using single features. Remarkably, in high responders, protein network analysis suggested a protein signature characteristic of low-grade inflammation. Alongside, in silico drug repurposing highlighted potential treatment options employing antidiabetic and anti-inflammatory drugs. Taken together, we present here an integrated pipeline that harnesses bio-psycho-physiological data for prognostic prediction in a translational approach. This pipeline opens new avenues for clinical application with the goal of stratifying patients and identifying potential new targets, as well as mechanistic correlates, for postsurgical pain.

Rationale and design of a large trial of perioperative ketamine for prevention of chronic post-surgical pain

BACKGROUND

Chronic post-surgical pain (CPSP) is recognised as one of the most common and debilitating complications of major surgery. Progression from acute to chronic pain after surgery involves sensitisation of central nervous system pathways with the N-methyl-D-aspartate (NMDA) receptor having a central role. Ketamine is a potent, non-selective NMDA antagonist commonly used for management of acute postoperative pain. Inconsistent but largely supportive evidence from small trials of a preventative effect of perioperative ketamine on CPSP risk suggests that a confirmative large trial is needed.

METHODS

The ROCKet (Reduction Of Chronic Post-surgical Pain with Ketamine) Trial is a multicentre, double-blind, placebo-controlled, individually randomised superiority trial conducted in 36 hospitals across Australia, New Zealand, and Hong Kong. The trial aims to recruit 4884 patients undergoing abdominal, thoracic, or major orthopaedic surgery. Eligible participants are randomised equally to perioperative intravenous ketamine or placebo for up to 72 h. Incidence of pain in the area of the index surgery is measured by structured telephone interview at 3 months (primary trial endpoint) and 12 months. Pain severity, nature, and associated psychological and quality of life indices are measured using the modified Brief Pain Inventory short form, Neuropathic Pain Questionnaire, Kessler K-10 Psychological Distress Scale, Pain Catastrophising Scale, EQ-5D-3L, and measures of healthcare utilisation and costs. The trial is being conducted by the Department of Critical Care, University of Melbourne, and the Australian and New Zealand College of Anaesthetists Clinical Trials Network. The trial is funded by the Australian National Health and Medical Research Council.

DISCUSSION

The ROCKet trial will clarify the effectiveness of ketamine in primary prevention of CPSP. In addition, it will provide high-quality, prospective data on the epidemiology of CPSP which will better inform further research into prevention and management of CPSP.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12617001619336) on the date of 12/11/2017.

Predictive Scores for Identifying Chronic Opioid Dependence After General Anesthesia Surgery

Purpose

To address the prevalence and risk factors of postoperative chronic opioid dependence, focusing on the development of a predictive scoring system to identify high-risk populations.

Methods

We analyzed data from the Taiwan Health Insurance Research Database spanning January 2016 to December 2018, encompassing adults undergoing major elective surgeries with general anesthesia. Patient demographics, surgical details, comorbidities, and preoperative medication use were scrutinized. Wu and Zhang's scores, a predictive system, were developed through a stepwise multivariate model, incorporating factors significantly linked to chronic opioid dependence. Internal validation was executed using bootstrap sampling.

Results

Among 111,069 patients, 1.6% developed chronic opioid dependence postoperatively. Significant risk factors included age, gender, surgical type, anesthesia duration, preoperative opioid use, and comorbidities. Wu and Zhang's scores demonstrated good predictive accuracy (AUC=0.83), with risk categories (low, moderate, high) showing varying susceptibility (0.7%, 1.4%, 3.5%, respectively). Internal validation confirmed the model's stability and potential applicability to external populations.

Conclusion

This study provides a comprehensive understanding of postoperative chronic opioid dependence and introduces an effective predictive scoring system. The identified risk factors and risk stratification allow for early detection and targeted interventions, aligning with the broader initiative to enhance patient outcomes, minimize societal burdens, and contribute to the nuanced management of postoperative pain.

Intrinsic anti-inflammatory nanomedicines for enhanced pain management

Introduction

Effective postoperative pain management remains a significant challenge due to the severe side effects of opioids and the limitations of existing analgesic delivery systems. Inflammation plays a critical role in pain exacerbation, highlighting the need for therapies that combine analgesic effects with intrinsic anti-inflammatory properties.

Methods

Herein, we develop an intrinsic anti-inflammatory nanomedicine designed to enhance pain management by integrating controlled anesthetic release with inherent anti-inflammatory activity. Our nanoplatform utilizes dendritic mesoporous silica nanoparticles (MSNs) loaded with levobupivacaine and coated with Rg3-based liposomes derived from ginsenoside Rg3, termed LMSN-bupi.

Results

The MSNs enable sustained and controlled release of the local anesthetic, while the Rg3-liposome coating provides intrinsic anti-inflammatory effects by inhibiting macrophage activation. In animal models, LMSN-bupi demonstrates significantly prolonged analgesic effects and attenuated inflammatory responses compared to traditional liposome-decorated nanoparticles (TMSN-bupi) (n = 5).

Discussion

These findings underscore the potential of intrinsic anti-inflammatory nanomedicines in enhancing pain management, offering a promising strategy to overcome the limitations of current therapies and improve patient outcomes in postoperative care.

Association between acute pain trajectory and patient-reported outcomes at 6-months following lumbar surgery for patients with lumbar degenerative disease

PURPOSE

To investigate the association between acute pain trajectory over one week and patient-reported outcomes (PRO) at 6-months following lumbar surgery in patients with lumbar degenerative disease (LDD).

METHODS

Two hundred and fifty-five subjects with LDD who received surgical treatment at our hospital between April 2019 and March 2022. Acute pain trajectory was measured using a pain trajectory calculator to determine an approximate line using the linear least squares method based on pain intensity on postoperative days 1, 3, 5, and 7. The pain trajectory-slope, which represents the change in postoperative pain intensity of the calculated approximation line, was evaluated as the main exposure for the present study. The PRO was assessed using the Oswestry Disability Index (ODI) measured at 6 ± 1 months postoperatively. Poor PRO scores in this study were defined using a threshold of an ODI of 22% or greater, which represents the patient acceptable symptomatic state after lumbar spine surgery. Multivariable logistic regression analysis including covariates was performed to investigate the association between pain trajectory-slope and PRO at 6-months following lumbar surgery.

RESULTS

In this study, 101 (39.6%) had poor PRO scores. Multivariable logistic regression analysis adjusted for covariates showed that pain trajectory-slope was associated with the poor PRO scores (odd ratios; 1.203, 95% confidence intervals; 1.130-1.288).

CONCLUSIONS

The results of this study show that acute pain trajectory is significantly associated with poor PRO scores 6-months after lumbar surgery. Patients with slower pain relief or worsening pain were associated with poor PRO scores.

A transcriptome data set for comparing skin, muscle and dorsal root ganglion between acute and chronic postsurgical pain rats

Chronic postsurgical pain (CPSP), with a high prevalence and rising epidemic of opioids crisis, is typically derived from acute postoperative pain. Our knowledge on the forming of chronic pain mostly derives from mechanistic studies of pain processing in the brain and spinal cord circuits, yet most pharmacological interventions targeting CNS came to be unhelpful in preventing CPSP. Revealing the peripheral mechanisms behind the transition from acute to chronic pain after surgery could shine a light on the novel analgesic regimens. Based on two recognized animal models in simulation of acute and chronic postsurgical pain, we provide a next-generation RNA sequencing (RNA-seq) data set to evaluate the time-course transcriptomic variation in the tissue of skin, muscle and dorsal root ganglion (DRG) in these two pain models. The aim of this study is to identify the potential origin and mechanism of the persistent postoperative pain, and further to explore effective and safer analgesic regimens for surgical patients.

Perioperative Analgesic Interventions for Reduction of Persistent Postsurgical Pain After Total Hip and Knee Arthroplasty: A Systematic Review and Meta-analysis

BACKGROUND

High pain levels immediately after surgery have been associated with persistent postsurgical pain. Still, it is uncertain if analgesic treatment of immediate postsurgical pain prevents the development of persistent postsurgical pain.

METHODS

We searched MEDLINE, CENTRAL, and Embase up to September 12, 2023, for randomized controlled trials investigating perioperative analgesic interventions and with reported pain levels 3 to 24 months after total hip or knee arthroplasty in patients with osteoarthritis. The primary outcome was pain score 3 to 24 months after surgery, assessed at rest and during movement separately. Two authors independently screened, extracted data, and assessed risk of bias using the Cochrane Risk of Bias 2 tool. We conducted meta-analyses and tested their robustness with trial sequential analyses and worst-best and best-worst case analyses.

RESULTS

We included 49 trials with 68 intervention arms. All but 4 trials were at high risk of bias for the primary outcome. Moreover, the included trials were heterogeneous in terms of exclusion criteria, baseline pain severity, and which cointerventions the participants were offered. For pain at rest, no interventions demonstrated a statistically significant difference between intervention and control. For pain during movement, perioperative treatment with duloxetine (7 trials with 641 participants) reduced pain scores at 3 to 24 months after surgery (mean difference -4.9 mm [95% confidence interval {CI}, -6.5 to -3.4] on the 0-100 visual analog scale) compared to placebo. This difference was lower than our predefined threshold for clinical importance of 10 mm.

CONCLUSIONS

We found no perioperative analgesic interventions that reduced pain 3 to 24 months after total hip or knee arthroplasty for osteoarthritis. The literature on perioperative analgesia focused little on potential long-term effects. We encourage the assessment of long-term pain outcomes.

Perioperative Regional Anesthesia on Persistent Opioid Use and Chronic Pain after Noncardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Whether regional anesthesia impacts the development of chronic postsurgical pain is currently debateable, and few studies have evaluated an effect on prolonged opioid use. We sought to systematically review the effect of regional anesthesia for adults undergoing noncardiac elective surgery on these outcomes.

METHODS

A systematic search was conducted in MEDLINE, EMBASE, CENTRAL, and CINHAL for randomized controlled trials (from inception to April 2022) of adult patients undergoing elective noncardiac surgeries that evaluated any regional technique and included one of our primary outcomes: (1) prolonged opioid use after surgery (continued opioid use ≥2 months postsurgery) and (2) chronic postsurgical pain (pain ≥3 months postsurgery). We conducted a random-effects meta-analysis on the specified outcomes and used the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach to rate the quality of evidence.

RESULTS

Thirty-seven studies were included in the review. Pooled estimates indicated that regional anesthesia had a significant effect on reducing prolonged opioid use (relative risk [RR] 0.48, 95% CI, 0.24-0.96, P = .04, I 2 0%, 5 trials, n = 348 patients, GRADE low quality). Pooled estimates for chronic pain also indicated a significant effect favoring regional anesthesia at 3 (RR, 0.74, 95% CI, 0.59-0.93, P = .01, I 2 77%, 15 trials, n = 1489 patients, GRADE moderate quality) and 6 months (RR, 0.72, 95% CI, 0.61-0.85, P < .001, I 2 54%, 19 trials, n = 3457 patients, GRADE moderate quality) after surgery. No effect was found in the pooled analysis at 12 months postsurgery (RR, 0.44, 95% CI, 0.16-1.17, P = .10).

CONCLUSIONS

The results of this study suggest that regional anesthesia potentially reduces chronic postsurgical pain up to 6 months after surgery. Our findings also suggest a potential decrease in the development of persistent opioid use.

Neuroplasticity in the transition from acute to chronic pain

Acute pain is a transient sensation that typically serves as part of the body's defense mechanism. However, in certain patients, acute pain can evolve into chronic pain, which persists for months or even longer. Neuroplasticity refers to the capacity for variation and adaptive alterations in the morphology and functionality of neurons and synapses, and it plays a significant role in the transmission and modulation of pain. In this paper, we explore the molecular mechanisms and signaling pathways underlying neuroplasticity during the transition of pain. We also examine the effects of neurotransmitters, inflammatory mediators, and central sensitization on neuroplasticity, as well as the potential of neuroplasticity as a therapeutic strategy for preventing chronic pain. The aims of this article is to clarify the role of neuroplasticity in the transformation from acute pain to chronic pain, with the hope of providing a novel theoretical basis for unraveling the pathogenesis of chronic pain and offering more effective strategies and approaches for its diagnosis and treatment.

The Effects of Phenyramidol and Diclofenac Treatment on Fracture Healing in Rats

Background

Fracture healing or nonunion refers to a process in which many factors interact. In this study, we aimed to evaluate the radiological, histological, and biomechanical effects of phenyramidol and diclofenac, which are frequently used to treat post-fracture ture pain worldwide, on fracture healing and nonunion in a rat femur fracture model.

Methods

In this study, 72 male Wistar-Albino rats aged 2-3 months and weighing 250 ± 30 g were divided into 4 main groups. The rats were divided into 12 subgroups according to the early, middle, and late periods. A fracture model was created in rat femurs, and surgical fixation was performed. Postoperative analgesic treatment protocols included phenyramidol, diclofenac, phenyramidol + diclofenac, and the control group. The rats were sacrificed on the fifteenth, thirtieth, and forty-fifth days and were evaluated radiologically, histopathologically, and biomechanically.

Results

Scoring was conducted independently by 2 orthopedists not involved in the study. When the results were analyzed statistically, no statistically significant difference was observed between the fifteenth and thirtieth day radiology score values of the control, diclofenac, phenyramidol, and Phenyramidol + diclofenac groups (p > 0.05), but there was a statistically significant difference (p < 0.05) between the forty-fifth day radiology score values of the control, diclofenac, phenyramidol, and phenyramidol + diclofenac groups.

Conclusions

Our study shows that the use of diclofenac or phenyramidol alone negatively affects postoperative fracture healing. However, this effect was less pronounced in the combined treatment group. Histologic examination revealed that neither treatment had a significant effect on healing. There were statistical differences in biomechanical and radiologic properties between the phenyramidol and diclofenac groups; in particular, the diclofenac group had lower biomechanical properties.

Effect of esketamine combined with pregabalin on acute postsurgical pain in patients who underwent resection of spinal neoplasms: a randomized controlled trial

ABSTRACT

Moderate-to-severe acute postsurgical pain (APSP) can prolong the recovery and worsen the prognosis of patients who undergo spinal surgery. Esketamine and pregabalin may resolve APSP without causing hyperpathia or respiratory depression after surgery. However, there are other risks, such as dissociative symptoms. We designed a randomized controlled trial to investigate the effect of the combination of these 2 drugs on the incidence of APSP in patients who underwent resection of spinal neoplasms. Patients aged 18 to 65 years were randomized to receive esketamine (a bolus dose of 0.5 mg·kg -1 and an infusion dose of 0.12 mg·kg -1 ·h -1 for 48 hours after surgery) combined with oral pregabalin (75-150 mg/day, starting 2 hours before surgery and ending at 2 weeks after surgery) or an identical volume of normal saline and placebo capsules. The primary outcome was the proportion of patients with moderate-to-severe APSP (visual analog scale score ≥ 40) during the first 48 hours after surgery. Secondary outcomes included the incidence of drug-related adverse events. A total of 90 patients were randomized. The incidence of moderate-to-severe APSP in the combined group (27.3%) was lower than that in the control group (60.5%) during the first 48 hours after surgery (odds ratio = 0.25, 95% CI = 0.10-0.61; P = 0.002). The occurrence of mild dissociative symptoms was higher in the combined group than in the control group (18.2% vs 0%). In conclusion, esketamine combined with pregabalin could effectively alleviate APSP after spinal surgery, but an analgesic strategy might increase the risk of mild dissociative symptoms.

Evaluation of Oral Pregabalin as a Preemptive Adjuvant for Postoperative Pain in Patients Undergoing Coronary Artery Bypass Grafting With General Anesthesia and High Thoracic Epidural: A Randomized Controlled Study

Aim This study aimed to evaluate the effectiveness of oral pregabalin as a preventive supplement in managing postoperative pain in patients undergoing coronary artery bypass grafting (CABG) with a combination of general anesthesia and high thoracic epidural anesthesia. Material and methods This 18-month randomized controlled study at a tertiary hospital's anesthesiology department included 62 American Society of Anesthesiologists (ASA) II or III patients aged 35-75 with left ventricular ejection fraction >35%. Placebo (Group B, n = 31) or pregabalin (Group A, n = 31) was randomly allocated. Group A got 150 mg of pregabalin the night before surgery and 75 mg on postoperative days 0 and 1, whereas Group B received a placebo. Postoperative pain was evaluated using the Verbal Numerical Scale and Visual Analogue Scale, while sedation was assessed with the Ramsay Sedation Scale. Statistical analysis was performed using SPSS for Windows, Version 16.0 (Released 2007; SPSS Inc., Chicago). Results In this study, pregabalin significantly reduced postoperative pain on Day 0 and Day 1 (p < 0.001) compared to the placebo. The pregabalin group exhibited higher sedation scores on Day 0 (p < 0.001), but there were no significant differences on Day 1. Inotrope requirements were similar between both groups. Conclusions CABG patients' postoperative pain was greatly reduced by pregabalin without impacting sedation or inotrope needs. These data imply that pregabalin was a useful supplementary analgesic for CABG patients' multimodal pain treatment.

Integrating mechanistic-based and classification-based concepts into perioperative pain management: an educational guide for acute pain physicians

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period.

Prevention of Post-Mastectomy Pain Syndrome: A Review of Recent Literature on Perioperative Interventions

PURPOSE OF REVIEW

Up to 60% of breast cancer patients continue to experience pain three months or more after surgery, with 15 to 25% reporting moderate to severe pain. Post-mastectomy pain syndrome (PMPS) places a high burden on patients. We reviewed recent studies on perioperative interventions to prevent PMPS incidence and severity.

RECENT FINDINGS

Recent studies on pharmacologic and regional anesthetic interventions were reviewed. Only nine of the twenty-three studies included reported a significant improvement in PMPS incidence and/or severity, sometimes with mixed results for similar interventions. Evidence for prevention of PMPS is mixed. Further investigation of impact of variations in dosing is warranted. In addition, promising newer interventions for prevention of PMPS such as cryoneurolysis of intercostal nerves and stellate ganglion block need confirmatory studies.

Dexborneol Amplifies Pregabalin's Analgesic Effect in Mouse Models of Peripheral Nerve Injury and Incisional Pain

Pregabalin is a medication primarily used in the treatment of neuropathic pain and anxiety disorders, owing to its gabapentinoid properties. Pregabalin monotherapy faces limitations due to its variable efficacy and dose-dependent adverse reactions. In this study, we conducted a comprehensive investigation into the potentiation of pregabalin's analgesic effects by dexborneol, a neuroprotective bicyclic monoterpenoid compound. We performed animal experiments where pain models were induced using two methods: peripheral nerve injury, involving axotomy and ligation of the tibial and common peroneal nerves, and incisional pain through a longitudinal incision in the hind paw, while employing a multifaceted methodology that integrates behavioral pharmacology, molecular biology, neuromorphology, and lipidomics to delve into the mechanisms behind this potentiation. Dexborneol was found to enhance pregabalin's efficacy by promoting its transportation to the central nervous system, disrupting self-amplifying vicious cycles via the reduction of HMGB1 and ATP release, and exerting significant anti-oxidative effects through modulation of central lipid metabolism. This combination therapy not only boosted pregabalin's analgesic property but also notably decreased its side effects. Moreover, this therapeutic cocktail exceeded basic pain relief, effectively reducing neuroinflammation and glial cell activation-key factors contributing to persistent and chronic pain. This study paves the way for more tolerable and effective analgesic options, highlighting the potential of dexborneol as an adjuvant to pregabalin therapy.

Association of peri-operative prescription of non-steroidal anti-inflammatory drugs with continued prescription of opioids after total knee arthroplasty: a retrospective claims-based cohort study

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the mainstays of multimodal pain management. While effective for acute pain control, recent pre-clinical evidence has raised concerns regarding an association between NSAIDs and chronic pain and potential opioid use. Our objective was to explore the association between peri-operative use of prescription NSAIDs and the need for continued opioid prescriptions lasting 90-180 days in previously opioid-naïve patients undergoing total knee arthroplasty. A database of health claims in the USA was used to identify all opioid-naïve adult patients who underwent primary knee arthroplasty between January 2010 and October 2021. We evaluated the magnitude of association between peri-operative prescription NSAID claims and claims for opioids at 90 days postoperatively using multivariable logistic regression models. Secondary outcomes included: the magnitude of association between peri-operative NSAID prescription and claims for opioids at 180 days postoperatively; and identifying other potential factors associated with opioid claims at 90 days postoperatively. After risk adjustment using multivariable logistic regression models in the 789,736-patient cohort, the adjusted odds ratio (95%CI) for a continuous claim of opioids at 90 and 180 days postoperatively among patients with a peri-operative NSAID prescription within 30 days was 1.32 (1.30-1.35), p < 0.001; and 1.12 (1.10-1.15), p < 0.001, respectively. This estimate of effect remained robust at 90 days after accounting for known potential confounders, including pre-existing knee pain and acute postoperative pain severity. Similar analysis of other pain medications (e.g. paracetamol) did not detect such an association. This population-based cohort study suggests that peri-operative prescription NSAID use may be associated with continued opioid prescription claims at 90 and 180 days after knee arthroplasty, even after adjusting for other observed covariates for continuous opioid claims. These novel findings can inform clinical decision-making for post-surgical pain management, risk-benefit discussions with patients and future research.

Dexamethasone and chronic postsurgical pain: the pendulum meets reductionistic thinking

Reductionist thinking results in the bulk of anaesthesia trial designs being a single intervention to address what are in fact complex processes. The Perioperative Administration of Dexamethasone and Infection (PADDI) trial assessed the safety of a single preoperative dose of dexamethasone. Surprising to most, in the original report, a single dose of dexamethasone increased the incidence of the secondary outcome chronic postsurgical pain. Was this a chance finding or does dexamethasone increase chronic postsurgical pain? In an attempt to address this question, the PADDI investigators have now analysed this prespecified secondary outcome in two ways: as a substudy published earlier in this Journal, and as a retrospective analysis of the ENIGMA-II chronic pain database in this issue of the Journal. The PADDI investigators have now presented enough data to convince us that indeed a single dose of dexamethasone is safe and effective. However, the increase in chronic postsurgical pain seen in the original PADDI publication highlights the complexities, and the possible immunologic mechanisms, behind the genesis of chronic postsurgical pain. These publications from the PADDI group raise questions about other anti-inflammatory agents we use regularly for long-term postoperative pain management, and highlights the need for well-designed clinical trials to address this critically important patient-centred adverse functional outcome.

Transcutaneous Electrical Nerve Stimulation Integrated into Pants for the Relief of Postoperative Pain in Hip Surgery Patients: A Randomized Trial

Background

The effect of transcutaneous electrical nerve stimulation (TENS) on pain and impression of change was assessed during a 2.5-hour intervention on the first postoperative days following hip surgery in a randomized, single-blinded, placebo-controlled trial involving 30 patients.

Methods

Mixed-frequency TENS (2 Hz/80 Hz) was administered using specially designed pants integrating modular textile electrodes to facilitate stimulation both at rest and during activity. The treatment outcome was assessed by self-reported pain Numerical Rating Scale (NRS) and Patient Global Impression of Change (PGIC) scores at four time points. The ability to perform a 3-meter walk test and the use of analgesics were also evaluated. Group comparison and repeated-measure analysis were carried out using nonparametric statistics.

Results

The active TENS group exhibited significantly higher PGIC scores after 30 minutes, which persisted throughout the intervention (all p ≤ 0.001). A reduction in NRS appeared after one hour of active TENS, persisting throughout the intervention (all p ≤ 0.05). The median group differences in pain ratings were greater than the minimum clinically important difference, and the analysis of pain trajectories confirmed clinical significance at the individual level. Moreover, patients in the active TENS group were more likely able to perform a 3-meter walk test by the end of the intervention (p = 0.04). Analysis of the opioid-sparing effect of TENS was inconclusive (p = 0.066). No postoperative surgical complications or TENS-related side effects were observed during the study.

Conclusion

Mixed-frequency TENS integrated in pants could potentially be an interesting addition to the arsenal of treatments for multimodal analgesia following hip surgery. This trial is registered with NCT05678101.

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.

The Impact of Acute Postoperative Pain in Developing Chronic Pain after Total Knee Arthroplasty

While total knee arthroplasties (TKAs) are performed with the intent to reduce pain, chronic postsurgical pain (CPSP) is one of the most well-documented complications that can occur following surgery. This study aimed to assess whether perioperative factors, focusing on acute postsurgical pain and perioperative opioid consumption, were associated with the development of chronic postsurgical pain. Under general anesthesia, 108 patients underwent TKA and were treated postoperatively with a multimodal analgesia approach. Numeric Rating Scale (NRS) pain scores at rest and with movement were recorded on postoperative days 0-3, 7, 14, and 30. Patients were sent a survey to assess chronic pain at months 22-66, which was examined as a single-group post hoc analysis. Based on the responses, patients were either classified into the CPSP or non-CPSP patient group. Chronic postsurgical pain was defined as an NRS score ≥ 4 with movement and the presence of resting pain. The primary outcome was a change in NRS. There were no differences in NRS pain scores with movement in the first 30 days postoperatively between patients with CPSP and without CPSP. Each unit increase in resting pain on postoperative days 3 and 14 was associated with significantly greater odds of CPSP presence (OR = 1.52; OR = 1.61, respectively), with a trend towards greater odds of CPSP at days 7 and 30 (OR = 1.33; OR = 1.43, respectively). We found that very intense pain in the initial phase seems to be related to the development of CPSP after TKA.

Effect of use of NSAIDs or steroids during the acute phase of pain on the incidence of chronic pain: a systematic review and meta-analysis of randomised trials

BACKGROUND

This study is the first to summarize the evidence on how the use of anti-inflammatory drugs during acute pain has an impact on the development of chronic pain.

METHODS

Randomized controlled trials retrieved from nine databases included anti-inflammatory drugs (NSAIDs or steroids) versus non-anti-inflammatory drugs in patients with acute pain and reported the incidence of chronic pain. No specified date, age, sex, or language restrictions. Subgroup analyses were performed according to pain classification, follow-up time, and medication. The GRADE method was used to evaluate quality of evidence.

RESULTS

A total of 29 trials (5220 patients) were included. Steroids or NSAIDs did not reduce the incidence of chronic nociceptive pain. Steroid use in acute phase significantly reduced the incidence of chronic neuropathic pain. In subgroup analysis, benefits were observed for methylprednisolone and dexamethasone, with some adverse effects. Steroids or NSAIDs were statistically significant in reducing pain intensity over 1 year, but the effect size was too small, and whether the long-term effect is clinically relevant needs to be further studied.

CONCLUSION

Quality of the evidence was low to moderate. No drug can be recommended to prevent chronic nociceptive pain. Injections of steroids (methylprednisolone or dexamethasone) during the acute phase reduce the incidence of chronic neuropathic pain, but most included studies also used local anesthetics. The results are indirect and need to be interpreted with caution. The pooled data effect sizes for pain intensity were small, so the clinical relevance was unclear. Study registration PROSPERO (CRD42022367030).

Intraoperative pharmacologic opioid minimisation strategies and patient-centred outcomes after surgery: a scoping review

BACKGROUND

Postoperative patient-centred outcome measures are essential to capture the patient's experience after surgery. Although a large number of pharmacologic opioid minimisation strategies (i.e. opioid alternatives) are used for patients undergoing surgery, it remains unclear which strategies are most promising in terms of patient-centred outcome improvements. This scoping review had two main objectives: (1) to map and describe evidence from clinical trials assessing the patient-centred effectiveness of pharmacologic intraoperative opioid minimisation strategies in adult surgical patients, and (2) to identify promising pharmacologic opioid minimisation strategies.

METHODS

We searched MEDLINE, Embase, CENTRAL, Web of Science, and CINAHL databases from inception to February 2023. We included trials investigating the use of opioid minimisation strategies in adult surgical patients and reporting at least one patient-centred outcome. Study screening and data extraction were conducted independently by at least two reviewers.

RESULTS

Of 24,842 citations screened for eligibility, 2803 trials assessed the effectiveness of intraoperative opioid minimisation strategies. Of these, 457 trials (67,060 participants) met eligibility criteria, reporting at least one patient-centred outcome. In the 107 trials that included a patient-centred primary outcome, patient wellbeing was the most frequently used domain (55 trials). Based on aggregate findings, dexmedetomidine, systemic lidocaine, and COX-2 inhibitors were promising strategies, while paracetamol, ketamine, and gabapentinoids were less promising. Almost half of the trials (253 trials) did not report a protocol or registration number.

CONCLUSIONS

Researchers should prioritise and include patient-centred outcomes in the assessment of opioid minimisation strategy effectiveness. We identified three potentially promising pharmacologic intraoperative opioid minimisation strategies that should be further assessed through systematic reviews and multicentre trials. Findings from our scoping review may be influenced by selective outcome reporting bias.

STUDY REGISTRATION

OSF - https://osf.io/7kea3.

Exploring the need for reconsideration of trial design in perioperative outcomes research: a narrative review

"Enhanced recovery after surgery" is a multimodal effort to control perioperative pathophysiology and improve outcome. However, despite advances in perioperative care, postoperative complications and the need for hospitalisation and prolonged recovery continue to be challenging. This is further complicated by procedure-specific and patient-associated risk factors, given the increase in the number of elderly and frail patients with multiple comorbidities undergoing surgery. This paper is a critical assessment of current methodology for trials in perioperative medicine. We make a plea to reconsider the design of future interventional trials to improve surgical outcome, based upon studies of potentially effective interventions, but often without improvements in recovery. The complexity of perioperative pathophysiology necessitates a procedure- and patient-specific approach whenever outcome is assessed or interventions are planned. With improved understanding of perioperative pathophysiology, the way to improve outcomes looks promising, provided that knowledge and established enhanced recovery programmes are integrated in trial design.

Funding

None.

Movement-evoked Pain versus Pain at Rest in Postsurgical Clinical Trials and in Meta-analyses: An Updated Systematic Review

BACKGROUND

Given the widespread recognition that postsurgical movement-evoked pain is generally more intense, and more functionally relevant, than pain at rest, the authors conducted an update to a previous 2011 review to re-evaluate the assessment of pain at rest and movement-evoked pain in more recent postsurgical analgesic clinical trials.

METHODS

The authors searched MEDLINE and Embase for postsurgical pain randomized controlled trials and meta-analyses published between 2014 and 2023 in the setting of thoracotomy, knee arthroplasty, and hysterectomy using methods consistent with the original 2011 review. Included trials and meta-analyses were characterized according to whether they acknowledged the distinction between pain at rest and movement-evoked pain and whether they included pain at rest and/or movement-evoked pain as a pain outcome. For trials measuring movement-evoked pain, pain-evoking maneuvers used to assess movement-evoked pain were tabulated.

RESULTS

Among the 944 included trials, 504 (53%) did not measure movement-evoked pain (vs. 61% in 2011), and 428 (45%) did not distinguish between pain at rest and movement-evoked pain when defining the pain outcome (vs. 52% in 2011). Among the 439 trials that measured movement-evoked pain, selection of pain-evoking maneuver was highly variable and, notably, was not even described in 139 (32%) trials (vs. 38% in 2011). Among the 186 included meta-analyses, 94 (51%) did not distinguish between pain at rest and movement-evoked pain (vs. 71% in 2011).

CONCLUSIONS

This updated review demonstrates a persistent limited proportion of trials including movement-evoked pain as a pain outcome, a substantial proportion of trials failing to distinguish between pain at rest and movement-evoked pain, and a lack of consistency in the use of pain-evoking maneuvers for movement-evoked pain assessment. Future postsurgical trials need to (1) use common terminology surrounding pain at rest and movement-evoked pain, (2) assess movement-evoked pain in virtually every trial if not contraindicated, and (3) standardize movement-evoked pain assessment with common, procedure-specific pain-evoking maneuvers. More widespread knowledge translation and mobilization are required in order to disseminate this message to current and future investigators.

EDITOR’S PERSPECTIVE

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.

Effects of S-ketamine added to patient-controlled analgesia on early postoperative pain and recovery in patients undergoing thoracoscopic lung surgery: A randomized double-blinded controlled trial

STUDY OBJECTIVE

To investigate whether the addition of S-ketamine to patient-controlled hydromorphone analgesia decreases postoperative moderate-to-severe pain and improves the quality of recovery (QoR) in patients undergoing thoracoscopic lung surgery.

DESIGN

Single-center prospective randomized double-blinded controlled trial.

SETTING

Tertiary university hospital.

PATIENTS

242 patients undergoing thoracoscopic lung surgery.

INTERVENTIONS

Patients were randomized to receive intravenous patient-controlled analgesia (IV-PCA) with hydromorphone alone or hydromorphone combined with S-ketamine (0.5 mg/kg/48 h, 1 mg/kg/48 h, or 2 mg/kg/48 h).

MEASUREMENTS

Primary outcome was proportion of patients with moderate-to-severe pain. (numerical rating scale [NRS] pain scores ≥4 when coughing) within 2 days after surgery. Postoperative QoR scores and other prespecified outcomes were also recorded.

MAIN RESULTS

Of 242 enrolled patients, 220 were included in the final analysis. The results demonstrated that the incidence of postoperative moderate-to-severe pain was significantly different between the hydromorphone group and combined S-ketamine group (absolute difference, 27.9%; 95% confidence interval [CI], 11.7% to 42.1%; P < 0.001). Patients who received S-ketamine had lower NRS pain scores at rest and when coughing on postoperative day 1 (POD1; median difference 1 and 1, P < 0.001) and postoperative day 2 (POD2; median difference 1 and 1, P < 0.001). The QoR-15 scores were higher in the combined S-ketamine group on POD1 (mean difference 6, P < 0.001) and POD2 (mean difference 6, P < 0.001) than in the hydromorphone group. A higher dose of S-ketamine was associated with deeper sedation. No differences were detected in the other safety outcomes.

CONCLUSIONS

Addition of S-ketamine to IV-PCA hydromorphone significantly reduced the incidence of postoperative moderate-to-severe pain and improved the QoR in patients undergoing thoracoscopic lung surgery.

TRIAL REGISTRATION

Chinese Clinical Trail Register (identifier: ChiCTR2200058890).

Efficacy and safety of add-on mirogabalin to conventional therapy for the treatment of peripheral neuropathic pain after thoracic surgery: the multicenter, randomized, open-label ADMIT-NeP study

BACKGROUND

For chronic pain after thoracic surgery, optimal timing of its diagnosis and effective treatment remains unresolved, although several treatment options are currently available. We examined the efficacy and safety of mirogabalin, in combination with conventional pain therapy (nonsteroidal anti-inflammatory drugs and/or acetaminophen), for treating peripheral neuropathic pain (NeP) after thoracic surgery.

METHODS

In this multicenter, randomized, open-label, parallel-group study, patients with peripheral NeP were randomly assigned 1:1 to mirogabalin as add-on to conventional therapy or conventional treatment alone.

RESULTS

Of 131 patients of consent obtained, 128 were randomized (mirogabalin add-on group, 63 patients; conventional treatment group, 65 patients). The least squares mean changes (95% confidence interval [CI]) in Visual Analogue Scale (VAS) score for pain intensity at rest from baseline to Week 8 (primary endpoint) were - 51.3 (- 54.9, - 47.7) mm in the mirogabalin add-on group and - 47.7 (- 51.2, - 44.2) mm in the conventional group (between-group difference: - 3.6 [95% CI: - 8.7, 1.5], P = 0.161). However, in patients with Self-administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) score (used for the screening of NeP) ≥ 12 at baseline, the greater the S-LANSS score at baseline, the greater the decrease in VAS score in the mirogabalin add-on group, while no such trend was observed in the conventional treatment group (post hoc analysis). This between-group difference in trends was statistically significant (interaction P value = 0.014). Chronic pain was recorded in 7.9% vs. 16.9% of patients (P = 0.171) at Week 12 in the mirogabalin add-on vs. conventional treatment groups, respectively. Regarding activities of daily living (ADL) and quality of life (QOL), changes in Pain Disability Assessment Scale score and the EQ-5D-5L index value from baseline to Week 8 showed significant improvement in the mirogabalin add-on group vs. conventional treatment group (P < 0.001). The most common adverse events (AEs) in the mirogabalin add-on group were dizziness (12.7%), somnolence (7.9%), and urticaria (3.2%). Most AEs were mild or moderate in severity.

CONCLUSIONS

Addition of mirogabalin to conventional therapy did not result in significant improvement in pain intensity based on VAS scores, but did result in significant improvement in ADL and QOL in patients with peripheral NeP after thoracic surgery.

TRIAL REGISTRATION

Japan Registry of Clinical Trials jRCTs071200053 (registered 17/11/2020).

Mechanisms inherent in acute-to-chronic pain after surgery - risk, diagnostic, predictive, and prognostic factors

PURPOSE OF REVIEW

Pain is an expected consequence of a surgery, but it is far from being well controlled. One major complication of acute pain is its risk of persistency beyond healing. This so-called chronic post-surgical pain (CPSP) is defined as new or increased pain due to surgery that lasts for at least 3 months after surgery. CPSP is frequent, underlies a complex bio-psycho-social process and constitutes an important socioeconomic challenge with significant impact on patients' quality of life. Its importance has been recognized by its inclusion in the eleventh version of the ICD (International Classification of Diseases).

RECENT FINDINGS

Evidence for most pharmacological and non-pharmacological interventions preventing CPSP is inconsistent. Identification of associated patient-related factors, such as psychosocial aspects, comorbidities, surgical factors, pain trajectories, or biomarkers may allow stratification and selection of treatment options based on underlying individual mechanisms. Consequently, the identification of patients at risk and implementation of individually tailored, preventive, multimodal treatment to reduce the risk of transition from acute to chronic pain is facilitated.

SUMMARY

This review will give an update on current knowledge on mechanism-based risk, prognostic and predictive factors for CPSP in adults, and preventive and therapeutic approaches, and how to use them for patient stratification in the future.

Healthcare delivery gaps in pain management within the first 3 months after discharge from inpatient noncardiac surgeries: a scoping review

BACKGROUND

Poor pain control during the postoperative period has negative implications for recovery, and is a critical risk factor for development of persistent postsurgical pain. The aim of this scoping review is to identify gaps in healthcare delivery that patients undergoing inpatient noncardiac surgeries experience in pain management while recovering at home.

METHODS

Searches were conducted by a medical librarian in PubMed, MEDLINE, EMBASE, EBSCO CINAHL, Web of Science, and Cochrane Database of Systematic Reviews for articles published between 2016 and 2022. Inclusion criteria were adults (≥18 yr), English language, inpatient noncardiac surgery, and included at least one gap in care for acute and/or persistent pain management after surgery within the first 3 months of recovery at home. Two reviewers independently screened articles for inclusion and extracted data. Quotations from each article related to gaps in care were synthesised using thematic analysis.

RESULTS

There were 4794 results from databases and grey literature, of which 38 articles met inclusion criteria. From these, 23 gaps were extracted, encompassing all six domains of healthcare delivery (capacity, organisational structure, finances, patients, care processes and infrastructure, and culture). Identified gaps were synthesised into five overarching themes: education (22 studies), provision of continuity of care (21 studies), individualised management (10 studies), support for specific populations (11 studies), and research and knowledge translation (10 studies).

CONCLUSIONS

This scoping review identified health delivery gaps during a critical period in postoperative pain management. These gaps represent potential targets for quality improvement and future research to improve perioperative care and longer-term patient-centred outcomes.

SCOPING REVIEW PROTOCOL

Open Science Framework (https://osf.io/cq5m6/).

Intraoperative Methadone in Next-day Discharge Outpatient Surgery: A Randomized, Double-blinded, Dose-finding Pilot Study

BACKGROUND

Contemporary perioperative practice seeks to use less intraoperative opioid, diminish postoperative pain and opioid use, and enable less postdischarge opioid prescribing. For inpatient surgery, anesthesia with intraoperative methadone, compared with short-duration opioids, results in less pain, less postoperative opioid use, and greater patient satisfaction. This pilot investigation aimed to determine single-dose intraoperative methadone feasibility for next-day discharge outpatient surgery, determine an optimally analgesic and well-tolerated dose, and explore whether methadone would result in less postoperative opioid use compared with conventional short-duration opioids.

METHODS

This double-blind, randomized, dose-escalation feasibility and pilot study in next-day discharge surgery compared intraoperative single-dose IV methadone (0.1 then 0.2, 0.25 and 0.3 mg/kg ideal body weight) versus as-needed short-duration opioid (fentanyl, hydromorphone) controls. Perioperative opioid use, pain, and side effects were assessed before discharge. Patients recorded pain, opioid use, and side effects for 30 days postoperatively using take-home diaries. Primary clinical outcome was in-hospital (intraoperative and postoperative) opioid use. Secondary outcomes were 30-day opioid consumption, pain, opioid side effects, and leftover opioid counts.

RESULTS

Median (interquartile range) intraoperative methadone doses were 6 (5 to 7), 11 (10 to 12), 14 (13 to 16), and 18 (15 to 19) mg in 0.1, 0.2, 0.25, and 0.3 mg/kg ideal body weight groups, respectively. Anesthesia with single-dose methadone and propofol or volatile anesthetic was effective. Total in-hospital opioid use (IV milligram morphine equivalents [MME]) was 25 (20 to 37), 20 (13 to 30), 27 (18 to 32), and 25 (20 to 36) mg, respectively, in patients receiving 0.1, 0.2, 0.25 and 0.3 mg/kg methadone, compared to 46 (33 to 59) mg in short-duration opioid controls. Opioid-related side effects were not numerically different. Home pain and opioid use were numerically lower in patients receiving methadone.

CONCLUSIONS

The most effective and well-tolerated single intraoperative induction dose of methadone for next-day discharge surgery was 0.25 mg/kg ideal body weight (median, 14 mg). Single-dose intraoperative methadone was analgesic and opioid-sparing in next-day discharge outpatient surgery.

EDITOR’S PERSPECTIVE

Descending Control of Nociception Poorly Predicts the Development of Persistent Postsurgical Pain-like Behavior in Consomic Dahl S Rat Strains

BACKGROUND

Chronic postsurgical pain is a poorly recognized outcome of surgery where patients experience pain long after healing from the surgical insult. Descending control of nociception, a phenomenon whereby application of a strong nociceptive stimulus to one part of the body of animals inhibits pain in remote body regions, offers one strategy to identify a propensity to develop chronic postsurgical pain-like behavior. Here, consomic rat panel was used to test the hypothesis that pain persistence is mechanistically linked to ineffective descending control of nociception.

METHODS

Male and female Brown Norway, Dahl S, and eight consomic strains (SS-xBN) were used to determine the presence of chronic postsurgical pain-like behaviors by using paw-withdrawal threshold evaluation (von Frey method) in the area adjacent to a hind paw plantar incision. Descending control of nociception was assessed by measuring hind paw-withdrawal thresholds (Randall-Selitto method) after capsaicin (125 µg) injection into a forepaw. Consomic rats were developed by introgressing individual Brown Norway chromosomes on the Dahl S rat genetic background, as Dahl S rats lack preoperative descending control of nociception.

RESULTS

Substitution of several chromosomes from the "pain-resistant" Brown Norway to the "pain-prone" Dahl S/Medical College of Wisconsin reduced mechanical nociceptive sensitivity and increased endogenous pain modulation capacity by differing degrees. Statistical modeling of these data revealed that descending control of nociception is a poor general predictor of the propensity to develop chronic postsurgical pain-like behavior (poor fit for model 1). However, a significant strain-by-descending control of nociception interaction was revealed (model 3, -2*log likelihood; 550.668, -2ll change; 18.093, P = 0.034) with SS-13BN and SS-15BN strains showing a negative descending control of nociception relationship with chronic postsurgical pain-like behavior.

CONCLUSIONS

Descending control of nociception poorly predicted which rat strains developed chronic postsurgical pain-like behavior despite controlling for genetic, environmental, and sex differences. Two consomic strains that mimic clinical chronic postsurgical pain criteria and display a strong negative correlation with descending control of nociception were identified, offering novel candidates for future experiments exploring mechanisms that lead to chronic postsurgical pain.

EDITOR’S PERSPECTIVE

Brain structural correlates of postoperative axial pain in degenerative cervical myelopathy patients following posterior cervical decompression surgery: a voxel-based morphometry study

OBJECTIVE

To investigate the brain structural correlates of postoperative axial pain (PAP) in degenerative cervical myelopathy (DCM) following posterior cervical decompression surgery.

METHODS

Structural images with high-resolution T1 weighting were collected from 62 patients with DCM and analyzed, in addition to 42 age/gender matched subjects who were healthy. Voxel-based morphometry (VBM) was analyzed, grey matter volume (GMV) was computed. One-way ANOVA was performed to reveal the GMV differences among DCM patients with PAP, patients without PAP and healthy controls (HC). Post-hoc analyses were conducted to identify the pair-wise GMV differences among these three groups. Analyses of correlations were conducted to uncover the link between clinical measurements and GMV variations. Last, support vector machine (SVM) was conducted to test the utility of GMV for classifying PAP and nPAP DCM patients.

RESULTS

Three main findings were observed: [1] Compared to healthy controls, DCM patients showed a significantly lower GMV in the precuneus preoperatively. DCM patients with PAP also exhibited a lower GMV within precuneus than those without; [2] In DCM patients with PAP, the precuneus GMV was inversely related to the postoperative pain intensity; [3] Moreover, successful classification between PAP and nPAP were observed via SVM based on precuneus GMV as features.

CONCLUSION

In summary, our results indicate that precuneus GMV may be linked to PAP in DCM, and could be employed to forecast the emergence of PAP in DCM patients.

Successful neurolytic thoracic sympathetic ganglion block using C-arm fluoroscopic cone-beam computed tomography in patients with postmastectomy pain syndrome: a report of 3 cases

BACKGROUND

Postmastectomy pain syndrome involves persistent neuropathic and sympathetically maintained neuropathic pain that can be improved using a thoracic sympathetic ganglion block. However, conventional fluoroscopic procedures pose technical difficulties and are associated with potential severe complications. We report the use of C-arm fluoroscopic cone-beam computed tomography to enhance procedural success and treatment safety.

CASE PRESENTATION

Three women diagnosed with postmastectomy pain syndrome and experiencing persistent pain underwent C-arm fluoroscopic cone-beam computed tomography-assisted ethanol neurolytic thoracic sympathetic ganglion block. Pain severity decreased substantially after the procedure. The therapeutic effects were sustained for 12 months in cases 1 and 2 and for 5 months in case 3. All patients experienced a remarkable decrease in allodynia and hyperalgesia intensities.

CONCLUSION

C-arm fluoroscopic cone-beam computed tomography-assisted neurolytic thoracic sympathetic ganglion block offers a valuable alternative for managing otherwise intractable postmastectomy pain syndrome before considering more invasive techniques.

A Randomized, Double-Blind, Placebo-Controlled Trial to Evaluate the Therapeutic Effect of Magnesium-L-Threonate Supplementation for Persistent Pain After Breast Cancer Surgery

Purpose

Post-mastectomy pain syndrome is a common yet debilitating neuropathic complication after breast cancer procedures, resulting in significantly reduced quality of life. Recently, emerging evidence has supported the therapeutic effect of magnesium administration in chronic pain. However, the role of magnesium supplementation in development of chronic pain after breast cancer surgery remains less known. The aim of this study was to evaluate therapeutic effect of magnesium supplementation on persistent pain after breast cancer procedure.

Patients and Methods

This was a randomized, double-blind, placebo-controlled clinical trial. A total of 109 patients who underwent breast cancer procedure received magnesium-L-threonate (n = 48) or placebo (n = 61) for 12 weeks. Chronic pain incidence, short form of the McGill Pain Questionnaire (SF-MPQ), Generalized Anxiety Disorder Scale (GAD-7), Patient Health Questionnaire-9 (PHQ-9), Pittsburgh Sleep Quality Index (PSQI), and Telephone Interview for Cognitive Status (TICS) were evaluated at 3- and 6-month follow-up.

Results

About 31% (15 out of 48) of patients reported chronic pain after magnesium supplementation, and 26% (16 out of 61) of the control group at 6-month follow-up respectively. Total scores of SF-MPQ were significantly increased in the control group 6 months after surgical intervention (mean difference, 1.475; 95% CI, -2.730 to -0.2211), but NOT in the magnesium treated group (mean difference, 1.250; 95% CI, -2.775 to 0.2748). No significant differences were found between two cohorts on SF-MPQ, GAD-7, PHQ-9, PSQI, or TICS at each timepoint.

Conclusion

Oral supplementation of magnesium-L-threonate did not effectively prevent the development of persistent pain in breast cancer survivors, nor provide sufficient pain relief over placebo. We did not observe improvement of pain, mood, sleep disorder, or cognitive function after 12-week magnesium supplementation. Future study may focus on magnesium combined with other effective anti-neuropathic pain treatment.

The mechanisms and management of persistent postsurgical pain

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

Transitional Pain Medicine; New Era, New Opportunities, and New Journey

Chronic postsurgical pain (CPSP), also known as persistent postsurgical pain (PPSP), is pain that develops or increases in intensity after a surgical procedure and lasts more than 3 months. Transitional pain medicine is the medical field that focuses on understanding the mechanisms of CPSP and defining risk factors and developing preventive treatments. Unfortunately, one significant challenge is the risk of developing opioid use dependence. Multiple risk factors have been discovered, with the most common, and modifiable, being uncontrolled acute postoperative pain; preoperative anxiety and depression; and preoperative site pain, chronic pain, and opioid use.

Dexamethasone and persistent wound pain: a prespecified analysis of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial

BACKGROUND

Dexamethasone is commonly administered intraoperatively to prevent postoperative nausea and vomiting and is believed to have analgesic properties. It is unknown whether it has an impact on chronic wound pain.

METHODS

In this prespecified embedded superiority substudy of the randomised PADDI trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and were followed up for 6 months postoperatively. The primary outcome was the incidence of pain in the surgical wound at 6 months. Secondary outcomes included acute postoperative pain and correlates of chronic postsurgical pain.

RESULTS

We included 8478 participants in the modified intention-to-treat population (4258 in the dexamethasone group and 4220 in the matched placebo group). The primary outcome occurred in 491 subjects (11.5%) in the dexamethasone arm and 404 (9.6%) subjects in the placebo arm (relative risk 1.2, 95% confidence interval 1.06-1.41, P=0.003). Maximum pain scores at rest and on movement in the first 3 postoperative days were lower in the dexamethasone group compared with the control group {median 5 (inter-quartile range [IQR] 3.0-8.0) vs 6 (IQR 3.0-8.0) and median 7 (IQR 5.0-9.0) vs 8 (IQR 6.0-9.0), P<0.001 for both}. Severity of postoperative pain was not predictive of chronic postsurgical pain. The severity of chronic postsurgical pain and the frequency of neuropathic features did not differ between treatment groups.

CONCLUSION

Administration of dexamethasone 8 mg i.v. was associated with an increase in the risk of pain in the surgical wound 6 months after surgery.

CLINICAL TRIAL REGISTRATION

ACTRN12614001226695.

Benefits versus harm of intraoperative glucocorticoid for postoperative nausea and vomiting prophylaxis

Intraoperative use of glucocorticoids is effective for postoperative nausea and vomiting prophylaxis and can also provide early postoperative analgesic effects, but the consequences for chronic post-surgical pain are debatable. In a secondary analysis of the large pragmatic Perioperative Administration of Dexamethasone and Infection trial (n=8478), the primary outcome of pain at the surgical wound at 6 months after surgery was increased in subjects receiving dexamethasone 8 mg i.v. for postoperative nausea and vomiting prophylaxis, a dose not associated with the detrimental effect of surgical site infection in the original study. In contrast, a more detailed assessment of chronic post-surgical pain after exclusion of patients with preoperative pain at the surgical site showed no differences with or without intraoperative dexamethasone regarding chronic post-surgical pain characteristics (intensity and neuropathic features). Because of several confounding factors especially regarding surgical details, these unexpected findings call for more well-designed studies about the potential risk of intraoperative treatments, such as glucocorticoids, on late post-surgical pain.

Non-opioid analgesics for the prevention of chronic postsurgical pain: a systematic review and network meta-analysis

BACKGROUND

Chronic postsurgical pain is common after surgery. Identification of non-opioid analgesics with potential for preventing chronic postsurgical pain is important, although trials are often underpowered. Network meta-analysis offers an opportunity to improve power and to identify the most promising therapy for clinical use and future studies.

METHODS

We conducted a PRISMA-NMA-compliant systematic review and network meta-analysis of randomised controlled trials of non-opioid analgesics for chronic postsurgical pain. Outcomes included incidence and severity of chronic postsurgical pain, serious adverse events, and chronic opioid use.

RESULTS

We included 132 randomised controlled trials with 23 902 participants. In order of efficacy, i.v. lidocaine (odds ratio [OR] 0.32; 95% credible interval [CrI] 0.17-0.58), ketamine (OR 0.64; 95% CrI 0.44-0.92), gabapentinoids (OR 0.67; 95% CrI 0.47-0.92), and possibly dexmedetomidine (OR 0.36; 95% CrI 0.12-1.00) reduced the incidence of chronic postsurgical pain at ≤6 months. There was little available evidence for chronic postsurgical pain at >6 months, combinations agents, chronic opioid use, and serious adverse events. Variable baseline risk was identified as a potential violation to the network meta-analysis transitivity assumption, so results are reported from a fixed value of this, with analgesics more effective at higher baseline risk. The confidence in these findings was low because of problems with risk of bias and imprecision.

CONCLUSIONS

Lidocaine (most effective), ketamine, and gabapentinoids could be effective in reducing chronic postsurgical pain ≤6 months although confidence is low. Moreover, variable baseline risk might violate transitivity in network meta-analysis of analgesics; this recommends use of our methods in future network meta-analyses.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42021269642.

Acute pain management and long term outcomes

PURPOSE OF REVIEW

The acute inflammatory reaction induced by tissue trauma causes pain but also promotes recovery. Recovery is highly variable among peoples. Effective acute pain (AP) management is very important but remains suboptimal what could affect long term outcomes. The review questions the impact of either failure or effectiveness of AP treatments and the choice of analgesic drugs on different long-term outcomes after tissue trauma.

RECENT FINDINGS

Pain control during mobilization is mandatory to reduce the risk of complications which exacerbate and prolong the inflammatory response to trauma, impairing physical recovery. Common analgesic treatments show considerable variability in effectiveness among peoples what argues for an urgent need to develop personalized AP management, that is, finding better responders to common analgesics and targeting challenging patients for more invasive procedures. Optimal multimodal analgesia to spare opioids administration remains a priority as opioids may enhance neuroinflammation, which underlies pain persistence and precipitates neurocognitive decline in frail patients. Finally, recent findings demonstrate that AP treatments which modulate nociceptive and inflammatory pain should be used with caution as drugs which inhibit inflammation like nonsteroidal antiinflammatory drugs and corticoids might interfere with natural recovery processes.

SUMMARY

Effective and safe AP management is of far greater importance than previously realized. Evidence of suboptimal AP management in many patients and recent reports pointing out the impact of current treatments on long term outcomes argue for further research in the field.

Flawed, futile, and fabricated-features that limit confidence in clinical research in pain and anaesthesia: a narrative review

The randomised controlled trial is the foundation of clinical research; yet there is concern that many trials have flaws in design, conduct, and reporting that undermine trustworthiness. Common flaws in trials include high risk of bias, small size, outcomes irrelevant to clinical care and patient's experience, and inability to detect efficacy even if present. These flaws carry forward into systematic reviews, which can confer the label of 'high-quality evidence' on inadequate data. Trials can be futile because their flaws mean that they cannot deliver any meaningful result in that different results in a small number of patients would be sufficient to change conclusions. Some trials have been discovered to be fabricated, the number of which is growing. The fields of anaesthesia and pain have more fabricated trials than other clinical fields, possibly because of increased vigilance. This narrative review examines these themes in depth whilst acknowledging an inescapable conclusion: that much of our clinical evidence is in trouble, and special measures are needed to bolster quality and confidence.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pharmacological Ischemic Conditioning with Roxadustat Does Not Affect Pain-Like Behaviors but Mitigates Sudomotor Impairment in a Murine Model of Deep Hind Paw Incision

Purpose

The involvement of hypoxic response mechanisms in local functional impairments in surgical wounds is unclear. In the present study, we characterized tissue hypoxia in surgical wounds and investigated the role of pharmacological ischemic conditioning (PIC) using roxadustat, an oral prolyl hydroxylase domain enzyme inhibitor, in postoperative local functional impairments in a murine model of deep hind paw incision.

Methods

Male BALB/cAJcl mice aged 9-13 weeks were used in all experiments. Plantar skins of mice that underwent surgical incision were subjected to immunohistochemistry to localise tissue hypoxia. Pain-like behaviours and sudomotor function were compared between mice treated with 6-week perioperative PIC and control mice. The effects of PIC were examined in vitro by immunocytochemistry using sympathetically differentiated PC12 cells and in vivo by immunohistochemistry using plantar skins collected on postoperative day 21.

Results

Prominent tissue hypoxia was detected within axons in the nerve bundles underneath surgical wounds. Six-week perioperative PIC using roxadustat failed to ease spontaneous pain-like behaviors; however, it mitigated local sudomotor impairment postoperatively. Upregulation of sympathetic innervation to the eccrine glands was observed in the PIC-treated skins collected on postoperative day 21, in accordance with the in vitro study wherein roxadustat promoted neurite growth of sympathetically differentiated PC12 cells.

Conclusion

This study suggests that tissue hypoxia is involved in the pathogenesis of local sudomotor dysfunction associated with surgical trauma. Targeting the hypoxic response mechanisms with PIC may be of therapeutic potential in postsurgical local sympathetic impairments that can be present in complex regional pain syndrome.

Preoperative pain hypersensitivity is associated with axial pain after posterior cervical spinal surgeries in degenerative cervical myelopathy patients: a preliminary resting-state fMRI study

OBJECTIVE

To test whether preoperative pain sensitivity is associated with the postoperative axial pain (PAP) in degenerative cervical myelopathy (DCM) and to explore its underlying brain mechanism.

METHODS

Clinical data and resting-state fMRI data of 62 DCM patients along with 60 age/gender matched healthy participants were collected and analysed. Voxel-wise amplitude of low frequency fluctuation (ALFF) was computed and compared between DCM patients and healthy controls. Correlation analyses were performed to reveal the association between the clinical metrics and brain alterations. Clinical data and ALFF were also compared between DCM patients with PAP and without PAP.

RESULTS

(1) Relative to healthy participants, DCM patients exhibited significantly lower preoperative pain threshold which is associated with the PAP intensity; (2) Relative to patients without PAP, PAP patients exhibited increased ALFF in mid-cingulate cortex (MCC) and lower preoperative pain threshold; (3) Further, multivariate pattern analysis revealed that MCC ALFF provide additional value for PAP vs. non-PAP classification.

CONCLUSION

In conclusion, our findings suggest that preoperative pain hypersensitivity may be associated with postoperative axial pain in degenerative cervical myelopathy patients. This finding may inspire new therapeutic ideas for patients with preoperative axial pain.

Successful use of differential target multiplexed spinal cord stimulation for chronic postsurgical abdominal pain

Introduction

Recent advances in stimulation techniques have improved the efficacy and expanded the applicability of spinal cord stimulation (SCS). Among these techniques, there are no reports on the efficacy of differential target multiplexed (DTM) SCS for chronic postsurgical pain (CPSP) after abdominal surgery. Therefore, we present the successful use of DTM SCS for CPSP after distal pancreatectomy.

Methods

A 49-year-old man with hypertension and severe chronic low back pain presented with neuropathic CPSP involving the left abdomen in the area of a laparotomy incision. His pain was refractory to conservative treatment and was rated 10 on a numerical rating scale (NRS). He underwent permanent implantation of a pulse generator after a 14-day trial stimulation.

Results

Chronic postsurgical pain was well controlled (NRS 1-2) at a 3-month follow-up with DTM SCS.

Conclusion

Differential target multiplexed SCS can be a new treatment option for neuropathic CPSP that is resistant to conservative treatment. It is important to further examine the characteristics of CPSP and identify appropriate candidates for the successful use of DTM SCS.

Evaluation of Health Care Providers Satisfaction with the Implementation of a Transitional Pain Service

Chronic postsurgical pain develops in 10% of patients undergoing surgery. Recently, multidisciplinary, patient-tailored interventions, such as a Transitional Pain Service (TPS) have been developed and implemented to improve perioperative pain management and thereby prevent chronic postsurgical pain. The purpose of this survey was to analyse health care providers satisfaction and learn from their experiences on the implementation of a TPS. In the TRUST study, a randomized controlled trial investigating the effectiveness of a TPS, 176 patients were enrolled. Afterwards, a satisfaction survey was internally developed, which consisted of eight items. Satisfaction was measured using a Likert scale with five response options from never (1 point) to always (5 points). Surveys were sent to all anaesthetists and anaesthesia residents in our department that were faced with the consequences of TPS implementation. In May 2022, 36 caregivers of the Department of Anaesthesiology returned the survey after four rounds of distribution, with a response rate of 82.3%. Thirty staff members (81.0%) strongly felt that patient care had improved with the introduction of a TPS and 33 (86.8%) would like to see the TPS to be continued in the future. Health care provider satisfaction improved after implementation of a TPS in our hospital.