Research design considerations for single-dose analgesic clinical trials in acute pain: IMMPACT recommendations

Paramedic analgesia comparing ketamine and morphine in trauma (PACKMaN): a randomised, double-blind, phase 3 trial

Background

Paramedics frequently administer analgesic medications for pain following trauma. Morphine is the most commonly administered strong analgesic. However, it may not be the best option as it may lower blood pressure, depress respiration and there is a risk of dependency. Ketamine might be a better option due to speed of onset and favourable side-effect profile. We sought to compare clinical effectiveness of paramedic administered ketamine and morphine in patients with severe pain following trauma.

Methods

PACKMaN was a double-blinded, randomised controlled, superiority trial, conducted in two regional ambulance services in the UK. Eligible patients were 16 years of age or over, had an acute injury, and articulated a pain score of 7 or greater on a 0-10 numeric rating score (NRS). We excluded pregnant patients, prisoners, those unable to articulate a pain score and anyone lacking capacity. The randomisation list prepared by the study programmer, utilised a permuted, unstratified, block randomisation system (variable size blocks) to achieve an overall ratio of 1:1 control (morphine): intervention (ketamine). Treatment packs were identical in appearance, apart from their unique sequential number. Individual participant randomisation occurred when the attending paramedic opened the treatment pack. The maximum available dose of morphine was 20 mg while the maximum available dose of ketamine was 30 mg. The treating paramedic administered the trial drug slowly, in regular small aliquots, via the intravenous (or intraosseous) route, titrating treatment until the patient reported adequate analgesia or requested that treatment stop due to undesired side effects. Timing of drug administration was not prespecified. The primary outcome was the Sum of Pain Intensity Difference (SPID) score on arrival to the hospital, calculated using patient reported NRS scores. Analysis was performed on an intention to treat basis. PACKMaN is registered with the International Clinical Trials Registry (ISRCTN14124474).

Findings

PACKMaN recruited its first patient on 10/11/2021 and achieved its recruitment target on 16/05/2023. We randomised 449 participants: 219 (49%) received ketamine and 230 (51%) received morphine. The SPID score was 3.5 (SD 2.8) for ketamine and 3.4 (SD 3.0) for morphine. We found no significant difference in efficacy between drugs (adjusted mean difference 0.1, 95%CI -0.4 to 0.6, p = 0.74). There was no significant difference in the incidence of serious adverse events [4 (2%) ketamine; 8 (3%) morphine]. There were no treatment related deaths.

Interpretation

Ketamine did not provide superior analgesia than morphine when used by paramedics to treat acute severe trauma pain. Unexpected adverse events occurred infrequently. Despite analgesia, many patients still experienced pain on arrival at hospital, highlighting the need for further research.

Funding

PACKMaN was funded by the National Institute for Health and Care Research.

Comparing Analgesic Regimen Effectiveness and Safety after Surgery (CARES): protocol for a pragmatic, international multicentre randomised trial

INTRODUCTION

Acute pain is commonly experienced by millions of patients who undergo outpatient surgical procedures. Moreover, an increasing number of procedures are performed on an outpatient basis, requiring greater postoperative planning to ensure effective pain management. Analgesic approaches commonly involve prescription opioids and non-steroidal anti-inflammatory drugs (NSAIDs), but an optimal regimen that balances pain and adverse effects has not been identified. In addition, critical gaps in evidence exist regarding how opioids and NSAIDs compare as analgesic regimens after surgery.

METHODS AND ANALYSIS

The Comparing Analgesic Regimen Effectiveness and Safety after Surgery (CARES) trial is a pragmatic, international, multicentre randomised trial that enrols adults undergoing three elective surgical procedures (laparoscopic cholecystectomy, breast lumpectomy, hernia repair). Participants are randomised to receive discharge analgesic prescriptions that consist of either NSAIDs or low-dose opioids (ie, 10 pills of oxycodone 5 mg or equivalent), with both groups prescribed acetaminophen around-the-clock. The primary effectiveness outcome is patient-reported worst daily pain intensity over the first 7 days after surgery. The primary safety outcome is the occurrence of opioid and/or NSAID side effects over the first 7 days after surgery. Secondary outcomes are assessed by patient report and medical record review at 1 week, 1 month, 3 months and 6 months after surgery and include sleep disturbance, patient perception of improvement/change after treatment, pain interference, anxiety, depression, health-related quality of life, clinically important adverse events, substance use, opioid misuse, chronic pain, healthcare utilisation related to pain and quality of recovery.

ETHICS AND DISSEMINATION

Investigational review boards at the University of Michigan and other sites have approved the CARES trial. The first patient enrolled in CARES in February 2023, with recruitment anticipated through 2026. Dissemination builds on the input of patient partners and other members of an engaged Stakeholder Advisory Board, with activities spanning co-production of summaries to share results with study participants, publications in biomedical journals and lay press, presentations to scientific and community organisations, and other multimedia communication materials.

TRIAL REGISTRATION NUMBER

NCT05722002.

Intradermally injected abobotulinumtoxinA administered preemptively before surgery alleviates post-surgical pain and normalizes behavior in a translational animal model

Previously, abobotulinumtoxinA (aboBoNT-A) injected intraoperatively resulted in effective, but delayed post-surgical analgesia in pigs. Here, we explore the efficacy of preemptively administered aboBoNT-A in intact animals on pain and associated behaviors following a full-skin-muscle incision and retraction surgery on the lower back. AboBoNT-A (200 U/animal) or saline, distributed across ten points, were injected around anticipated incision 15, 5, or 1 day before surgery via ID route (part A) or 15 days before surgery via ID, intramuscular (IM) or subcutaneous (SC) routes (part B). We assessed mechanical sensitivity (withdrawal force; WF), distress behavior score (DBS), and latency to approach the investigator before and after surgery for 7 days.AboBoNT-A, injected ID 15 days before surgery, didn't alter any baseline behaviors, but resulted in 5-fold increases in WF, 75% reduction in DBS and 70% reduction in approach latencies (all p < 0.01). Injections 5 days before surgery led to similar effects, albeit with a fewer animals reaching thresholds, while those made 1 day before surgery were less effective. SC and IM injections were ineffective. Thus, aboBoNT-A administered ID 15 days before surgery represents the most optimal condition for postoperative analgesia. These findings warrant for clinical investigation of preemptively administered aboBoNT-A in postsurgical pain.

Early opioid administration and pain-related patient-reported outcomes on the first postoperative day: an analysis of data from 111,693 patients in 392 surgical wards in Germany

ABSTRACT

The risk-benefit ratio of perioperative opioid analgesia is controversial. Few studies have analyzed the effectiveness of opioids in the early postoperative period. To analyze the effectiveness of early opioid administration in this period in a large number of surgeries in routine care, we compared pain-related outcomes between patients treated on wards with different rates of early opioid administration. In this observational study, we analyzed data from 111,693 patients in 392 surgical wards between 2010 and 2022 within the German Quality Improvement in Postoperative Pain Management registry. We defined early opioid administration at the ward-level as the percentage of patients who received at least 1 opioid dose between the end of surgery and data collection on the first postoperative day, including recovery room and ward. To identify different patterns of early opioid administration, we considered these percentages in patients with mild, moderate, and severe pain and applied k-means clustering. We performed mixed regression analyses to assess associations between clusters and patient-reported outcomes on the first postoperative day. At the ward-level, the median percentage of early opioid administration was 79.5% (first-third quartile: 64.5%-92.0%), and 2 clusters of wards were identified. In clusters 1 and 2, an opioid was administered in 58.5% and 89.0% of patients, respectively. Patients in cluster 2 reported better outcomes for pain intensity and pain-related interference but worse outcomes for nausea. However, the effect sizes were small. Patients treated on surgical wards with a higher rate of early opioid administration reported slightly better pain-related outcomes on the first postoperative day.

Preoperative measures of pain at rest and movement-evoked pain in knee arthroplasty: Associations with pain and function outcome trajectories from a prospective multicentre longitudinal cohort study

BACKGROUND

The study of pain at rest (PAR) and movement-evoked pain (MEP) in persons with musculoskeletal pain has received substantial attention. Despite strong interest, relatively little attention has been directed to the psychometric development of these constructs. Our purpose was to explore the relationship between PAR and MEP and to examine the prognostic utility of these measures in persons with knee arthroplasty.

METHODS

We used prospectively collected data from persons scheduled for knee arthroplasty who had moderate to high levels of pain catastrophizing. Preoperative latent variables for PAR and MEP were developed and used to determine if they were associated with a binary latent variable of good versus poor pain and function outcome trajectories. Factor correlations were used to determine the extent to which the variance for PAR and MEP was overlapping.

RESULTS

PAR and MEP are significant predictors of good versus poor pain and function classes. Odds ratios ranged from 1.21 to 1.64 (p < 0.001) indicating a significant increase in the likelihood of poor outcome. Correlation between PAR and MEP latent variables was high (r = 0.89; 95% CI: 0.86-0.92) indicating substantially overlapping variance.

CONCLUSIONS

PAR and MEP, as defined in our study, can be used to make prognostic judgements regarding risk of poor postoperative outcome trajectory following knee arthroplasty. However, PAR and MEP showed substantially overlapping variance indicating that measurements of both are not necessary when making prognostic assessments.

SIGNIFICANCE STATEMENT

Preoperative PAR and MEP latent variables, as defined in our study, had prognostic significance for 1 year pain and function outcome trajectories. PAR and MEP latent variables had substantially overlapping variance which suggested that only one is needed to make prognostic judgements. The prognostic significance of PAR and MEP as well as their substantially overlapping variance is new to the field prognostic research in knee arthroplasty.

A randomised, double-blind, placebo-controlled study to determine the analgesic efficacy, safety and tolerability of VPX638 administered topically to painful wounds

New analgesics are needed for painful wounds. Multiple reports suggest that topical sevoflurane may have analgesic effects. This placebo-controlled randomised trial evaluated the analgesic efficacy and safety of VPX638 (topical sevoflurane). Seventy-eight participants with painful wounds, were enrolled at eight Australian centres and randomly allocated to receive 2 × 5 mL of VPX638 (N = 39) or placebo (N = 40) during one wound dressing change. Numerical pain rating scores and use of opioids were recorded for 24 h. The primary endpoint was pain during wound cleaning, secondary endpoints evaluated pain for 24 h after drug application and opioids use. There was no significant difference in mean pain scores during wound cleaning between VPX638 and placebo (0.854; p = 0.23). The mean differences in summed pain intensity difference from baseline suggested VPX638 provided greater analgesia compared to placebo over 8 h (p < 0.02), 12 h (p < 0.01) and 24 h (p < 0.05) and significantly longer duration of analgesia, 24.3 h for VPX638 versus 7.1 h for placebo (p < 0.01). In the 24 h after drug administration, participants receiving VPX638 had a 50% decrease in opioid use over 24 h compared with placebo. VPX638 appeared safe and well-tolerated. In conclusion, this small placebo-controlled randomised trial suggested that VPX638 provides analgesia and is opioid-sparing for up to 24 h after wound cleaning. It supports the need for further evaluation of the benefit of VPX638 as a topical analgesic for painful wounds.

Safety of Co-Crystal of Tramadol-Celecoxib (CTC) in Patients with Acute Moderate-to-Severe Pain: Pooled Analysis of Three Phase 3 Randomized Trials

INTRODUCTION

Multi-modal analgesia is desirable for the management of acute pain since it can provide effective pain relief at lower doses, thereby aiding tolerability. Co-crystal of tramadol-celecoxib (CTC) provides effective analgesia in models of acute pain. Co-crystallization can alter the pharmacokinetics of individual components, potentially improving tolerability. We sought to better understand the safety and tolerability of CTC in patients with acute postoperative pain.

METHODS

We conducted a pooled analysis of safety data from three phase 3 randomized controlled trials in adults with acute moderate-to-severe pain following oral surgery, bunionectomy, and elective abdominal hysterectomy. We present data for CTC 200 mg twice daily (BID) and its comparators: tramadol 50 mg four times daily (QID) (one trial), tramadol 100 mg QID (two trials), celecoxib 100 mg BID (two trials), and placebo (three trials).

RESULTS

In total, n = 551 patients received CTC 200 mg BID, n = 183 received tramadol 50 mg QID, n = 368 received tramadol 100 mg QID, n = 388 received celecoxib 100 mg BID, and n = 274 received placebo. The prevalence of adverse events (AEs) related to study drug up to 48 h was numerically lower with CTC 200 mg BID (35.9%) than with tramadol 50 mg QID (47.5%) and 100 mg QID (44.8%) but greater than with celecoxib 100 mg BID (12.4%) and placebo (20.4%). The most frequent AEs related to study drug up to 48 h were somnolence, nausea, dizziness, and vomiting, which occurred more frequently in patients receiving tramadol 100 mg QID than in those receiving CTC 200 mg BID.

CONCLUSION

CTC 200 mg BID appears to be better tolerated than tramadol 100 mg QID, possibly because of reduced total exposure to tramadol. This may contribute to a more favorable benefit-risk profile for CTC versus individual components, making it a promising treatment for acute pain.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT03108482, NCT02982161 (EudraCT: 2016-000592-24), NCT03062644 (EudraCT: 2016-000593-38).

Additive antinociceptive action of intrathecal anandamide reuptake inhibitor and morphine in the management of post-incisional pain in rats

Spinal opioids have mixed efficacy and their adverse effects force treatment cessation of postoperative pain. Consequently, there is an ongoing search for new therapeutic strategies. Here, we evaluated the analgesic efficacy of intrathecal UCM707, an anandamide reuptake inhibitor, and morphine combination. Firstly, we assessed the effects of morphine (1, 5 and 10 μg), UCM707 (75 μg) and its combination in the hot plate. Then, morphine + UCM707 at sub-effective doses was evaluated in a rat post-incisional pain model. In addition, μ-, CB1r-, CB2r- and TRPV1-antagonists were pre-administered before the combination. Activation of μ-opioid and CB1r, and Cnr1, Cnr2, Oprm1 and TRPV1 expressions were evaluated in the lumbar sacra and periaqueductal grey by [35 S]-GTPγS binding autoradiography and qPCR studies. In the hot plate, morphine (1 μg) and UCM707 (75 μg) induced a more robust analgesic effect than each drug alone. Morphine plus UCM707 did not modify μ-opioid nor CB1 receptor function in the PAG or LS. Cnr1 and TRPV1 expression increased in the lumbar sacra (LS). Morphine plus UCM707 significantly reduced post-incisional pain at 1 and 4 days after surgery. Cnr1, Cnr2 and TRPV1 expressions increased in the LS. Blockade of μ-opioid receptor reduced combination effects on days 1 and 4. CB1r- and CB2r-antagonism reduced morphine + UCM707 effects on days 1 and 4, respectively. CB1r and TRPV1-antagonism improved their antinociceptive effects on day 4. These results revealed a synergistic/additive analgesic effect of UCM707 and morphine combination controlling postincisional pain. CB1r, CB2r and TRPV1 contribute differently as central sensitization occurs.

Pain Reduction of Ibuprofen Sodium Dihydrate Alone and in Combination with Acetaminophen in an Untreated Endodontic Pain Model: A Randomized, Double-blind Investigation

INTRODUCTION

Most pain studies have been based on a postsurgical, third molar model using ibuprofen (IBU)/acetaminophen (APAP). Studies have found quicker onset of pain relief with a newer formulation of IBU - ibuprofen sodium dihydrate (ISD). The purpose of this study was to compare pain reduction of ISD/APAP to ISD in an acute endodontic pain model of untreated patients experiencing moderate to severe pain with symptomatic apical periodontitis.

METHODS AND MATERIALS

In this double-blind randomized study, 64 adult emergency patients in acute moderate to severe pain, a pulpal diagnosis of symptomatic irreversible pulpitis or necrosis, and symptomatic apical periodontitis participated. Each patient randomly received either one dose of 768 mg ISD/1000 mg APAP or one dose of 768 mg ISD. Pain intensity scores were recorded every 15 minutes over 240 minutes using the Heft-Parker VAS along with time to first sign of pain relief, time to meaningful pain relief, and time to 50% pain relief also recorded. The data were analyzed statistically.

RESULTS

Both ISD and ISD/APAP groups showed a progressive decrease in pain from baseline to 120 minutes after medication administration. Afterward, a relative plateau was seen in the patients' pain. There was no difference in the VAS scores between the ISD and ISD/APAP at any given time point, time to first sign of pain relief, time to meaningful pain relief, and time to 50% pain relief.

CONCLUSIONS

The addition of APAP to ISD for pain control in an untreated endodontic pain model did not differ significantly from ISD alone.

Cannabinoid Analgesia in Postoperative Pain Management: From Molecular Mechanisms to Clinical Reality

Postoperative pain (POP) is a challenging clinical phenomenon that affects the majority of surgical patients and demands effective management to mitigate adverse outcomes such as persistent pain. The primary goal of POP management is to alleviate suffering and facilitate a seamless return to normal function for the patient. Despite compelling evidence of its drawbacks, opioid analgesia remains the basis of POP treatment. Novel therapeutic approaches rely on multimodal analgesia, integrating different pharmacological strategies to optimize efficacy while minimizing adverse effects. The recognition of the imperative role of the endocannabinoid system in pain regulation has prompted the investigation of cannabinoid compounds as a new therapeutic avenue. Cannabinoids may serve as adjuvants, enhancing the analgesic effects of other drugs and potentially replacing or at least reducing the dependence on other long-term analgesics in pain management. This narrative review succinctly summarizes pertinent information on the molecular mechanisms, clinical therapeutic benefits, and considerations associated with the plausible use of various cannabinoid compounds in treating POP. According to the available evidence, cannabinoid compounds modulate specific molecular mechanisms intimately involved in POP. However, only two of the eleven clinical trials that evaluated the efficacy of different cannabinoid interventions showed positive results.

A phase 3 active-controlled trial of liposomal bupivacaine via sciatic nerve block in the popliteal fossa after bunionectomy

STUDY OBJECTIVE

To investigate the efficacy, safety, pharmacodynamics, and pharmacokinetics of liposomal bupivacaine (LB) administered via ultrasound-guided sciatic nerve block in the popliteal fossa in participants undergoing bunionectomy.

DESIGN

Two-part, randomized, double-blind, active-controlled trial (NCT05157841).

SETTING

Operating room, postanesthesia care unit, and health care facility (6 sites).

PATIENTS

Adults with American Society of Anesthesiologists physical status classification ≤3 and body mass index ≥18 to <40 kg/m2 undergoing elective distal metaphyseal osteotomy.

INTERVENTIONS

Part A participants were randomized 1:1:1 to LB 266 mg, LB 133 mg, or bupivacaine hydrochloride 50 mg (BUPI). Part B participants were randomized 1:1 to LB (at the dose established by part A) or BUPI.

MEASUREMENTS

The primary endpoint was area under the curve (AUC) of numerical rating scale (NRS) pain intensity scores 0-96 h after surgery. Secondary endpoints included total postsurgical opioid consumption, opioid-free status 0-96 h after surgery, and pharmacokinetic endpoints.

MAIN RESULTS

Part A enrolled 22 participants per group. In part B, additional participants were randomized to LB 133 mg (n = 59) and BUPI (n = 60) (185 total). LB 133 mg had significant reductions versus BUPI in the AUC of NRS pain intensity score (least squares mean [LSM], 207.4 vs 371.4; P < 0.00001) and total opioid consumption 0-96 h after surgery (LSM, 17.7 [95% confidence interval (CI), 13.7, 22.8] morphine milligram equivalents [MMEs] vs 45.3 [95% CI, 35.1, 58.5] MMEs; P < 0.00001) and an increased proportion of opioid-free participants (24.4% vs 6%; odds ratio, 5.04 [95% CI, 2.01, 12.62]; P = 0.0003) in parts A + B. Adverse events were similar across groups.

CONCLUSIONS

LB 133 mg administered via sciatic nerve block in the popliteal fossa after bunionectomy demonstrated superior and long-lasting postsurgical pain control versus BUPI. The clinical relevance of these findings is supported by concurrent reductions in pain and opioid consumption over 4 days after surgery and a significantly greater percentage of participants remaining opioid-free.

Efficacy of Co-Crystal of Tramadol-Celecoxib (CTC) in Patients with Acute Moderate-to-Severe Pain: A Pooled Analysis of Data from Two Phase 3 Randomized Clinical Trials

BACKGROUND AND OBJECTIVES

New acute pain medications are needed that provide effective analgesia while minimizing side effects and opioid exposure. Clinical trials of co-crystal of tramadol-celecoxib (CTC) have demonstrated an improved benefit/risk profile versus tramadol or celecoxib alone. We pooled data from two phase 3 clinical trials to evaluate the efficacy of CTC 200 mg twice daily (BID) in acute moderate-to-severe pain.

METHODS

Efficacy data were pooled from STARDOM1 [acute pain following oral surgery (NCT02982161)] and ESTEVE-SUSA-301 [acute pain following bunionectomy (NCT03108482)]. The primary efficacy outcome was sum of pain intensity difference from 0 to 48 h (SPID0-48).

RESULTS

A total of 344 patients received CTC 200 mg BID, 342 received tramadol 50 or 100 mg four times a day, 181 received celecoxib 100 mg BID, and 172 received placebo. The least-squares mean difference in SPID0-48 was -21.8 (p = 0.002) for CTC versus tramadol and -72.8 (p < 0.001) for CTC versus placebo. A similar pattern of SPID0-48 was observed with CTC versus comparator whether patients had moderate or severe pain at baseline. Reduction in pain intensity was faster and reached mild intensity earlier with CTC versus comparators. Patients were significantly (p ≤ 0.005) less likely to receive rescue medication within 4 or 48 h with CTC compared with tramadol or placebo.

CONCLUSIONS

This pooled analysis reinforces the efficacy profile of CTC versus tramadol and, given that CTC permits lower daily tramadol dosing and thereby reduces unnecessary opioid use, this highlights its improved benefit/risk profile and its potential for the management of moderate-to-severe pain.

Clinical validation of a fast-acting acetaminophen: a randomized, active and placebo controlled dental pain study

OBJECTIVES

To address the need for faster pain relief of over-the-counter (OTC) analgesic users, a novel drug delivery technology was developed to achieve faster absorption of orally administered acetaminophen with the goal of delivering earlier onset of pain relief. Previous development studies suggested that a 1000 mg dose of this fast-acting acetaminophen (FA-acetaminophen) formulation provided faster absorption and onset of action versus, commercially available OTC fast-acting analgesics, 1000 mg of extra-strength acetaminophen (ES-acetaminophen) or 400 mg of liquid-filled ibuprofen capsules (LG-ibuprofen). This study was designed as the definitive trial evaluating the onset of pain relief of FA-acetaminophen versus these same OTC comparators.

METHODS

This single-dose, randomized, double-blind, placebo- and active-controlled clinical trial compared analgesic onset, overall efficacy, and safety of FA-acetaminophen 1000 mg, ES-acetaminophen 1000 mg, LG-ibuprofen 400 mg, and placebo over 4 h in a postsurgical dental pain model. Following removal of 3 to 4 impacted third molars, 664 subjects with moderate-to-severe pain were randomized in a 4:4:2:1 ratio to FA-acetaminophen (249), ES-acetaminophen (232), LG-ibuprofen (124), or placebo (59). Mean age was 18.9 years; 45.5% were male; 57.5% had severe baseline pain intensity. Subjects stopped a first stopwatch if/when they had perceptible pain relief and a second stopwatch if/when their pain relief became meaningful to them. Pain intensity difference (PID) and pain relief (PAR) were obtained using an 11-point numerical rating scale.

FINDINGS

FA-acetaminophen 1000 mg had faster median time to onset of pain relief (15.7 min) compared to ES-acetaminophen 1000 mg (20.2 min, p = 0.035), LG-ibuprofen 400 mg (23.2 min, p < 0.001), and placebo (non-estimable), statistically greater mean PAR and PID scores than other treatment groups at 15 and 30 min, and a statistically greater percentage of subjects with confirmed perceptible pain relief at 15 and 20 min. At 25 min, FA-acetaminophen 1000 mg had a statistically significantly greater percentage of subjects with confirmed perceptible pain relief than LG-ibuprofen 400 mg and placebo. No clinically significant adverse events were reported.

CONCLUSIONS

This study supports previous studies, demonstrating faster onset of analgesia with FA-acetaminophen 1000 mg compared to OTC ES-acetaminophen 1000 mg and OTC LG-ibuprofen 400 mg.

CLINICALTRIALS.GOV IDENTIFIER

NCT03224403 https://clinicaltrials.gov/ct2/show/NCT03224403.

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

Acupuncture for response and complete pain relief time of acute renal colic: Secondary analysis of a randomized controlled trial

Background

The integration of acupuncture with intramuscular injection of diclofenac sodium can expedite the onset of analgesia in treating acute renal colic caused by urolithiasis. However, it remains unclear whether acupuncture can accelerate pain relief constantly until complete remission. This study aimed to explore the extent to which acupuncture can expedite the onset time of response or complete pain relief in treating acute renal colic, and the predictive value of patient characteristics for treatment efficacy.

Methods

This secondary analysis utilized data from a prior randomized controlled trial. Eighty patients with acute renal colic were randomly assigned 1:1 to the acupuncture group or the sham acupuncture group. After intramuscular injection of diclofenac sodium, acupuncture or sham acupuncture was delivered to patients. The outcomes included time to response (at least a 50 % reduction in pain) and complete pain relief. Between-group comparison under the 2 events was estimated by Kaplan-Meier methodology. Subgroup analysis was performed utilizing the Cox proportional hazards model.

Results

The median response time and complete pain relief time in the acupuncture group were lower than those in the sham acupuncture group (5 vs 30 min, Log Rank P < 0.001; 20 min vs not observed, Log Rank P < 0.001, respectively). Hazard Ratios (HRs) for response across all subgroups favored the acupuncture group. All HRs for complete pain relief favored acupuncture, expect large stone and moderate pain at baseline. No interaction was found in either event.

Conclusion

Acupuncture can accelerate the response time and complete pain relief time for patients with acute renal colic, with the efficacy universally.

Trial registration

This study has been registered at Chinese Clinical Trial Registry: ChiCTR1900025202.

Boosting open-label placebo effects in acute induced pain in healthy adults (BOLPAP-study): study protocol of a randomized controlled trial

Introduction

Pain is a highly prevalent symptom in the hospital setting, but treatment options remain limited. Harnessing the placebo effect in an ethical manner could provide a new possibility to reduce pain in clinical practice. So called open-label placebos (OLP) have been shown to elicit significant effects in reducing acute pain. But, before implementation, more knowledge concerning the properties of OLPs is needed. This study aims to assess the duration of analgesic effects from OLP and to determine the possibility of boosting such effects.

Methods and analysis

This is the protocol of an ongoing (first patient enrolled in March 2023) single-site randomized trial investigating OLPs in two parts (i.e., substudies). In both parts, pain will be induced in healthy adults using an intradermal electrical stimulation model. Participants in Part 1 will have two study visits: An interventional visit with one OLP injection accompanied by an evidence-based treatment rationale and a control visit with no treatment. For Part 2, participants will be randomized into three groups: (1) A fixed-time "Booster" group including one single repetition of the OLP injection at a fixed time point, (2) an on-demand "Booster" group including one single repetition of the OLP injection on-demand, and (3) a control group who will receive just one OLP injection. Differences in pain ratings over time (using the Numeric Rating Scale) will be analyzed with several two-sample t-tests. The time point for a fixed-time "Booster" in Part 2 will be derived from Part 1 with additional statistical tools such as a broken-stick mixed-effect model.

Discussion

This study aims to further characterize the analgesic effects of OLPs. In doing so, it will provide valuable information needed for later implementation of OLPs in clinical practice, where they could play a role in multimodal analgesic concepts.

Ethics and dissemination

The "Ethikkommission Nordwest- und Zentralschweiz" (BASEC 2023-00296) approved the study protocol. Results of the analysis will be submitted for publication in a peer-reviewed journal.

Clinical Trial Registration

This study is registered at ClinicalTrials.gov (NCT05819476) and is listed in the Swiss National Registry at kofam.ch (SNCTP000005470).

The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac

Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.

Comparison of erector spinae plane block and serratus anterior plane block for postoperative analgesia in uniportal thoracoscopic lobectomy: a randomized controlled trial

BACKGROUND

Postoperative pain remains a significant concern following uniportal thoracoscopic surgery. The analgesic efficacy of erector spinae plane block (ESPB) and serratus anterior plane block (SAPB) in terms of postoperative opioid consumption in uniportal thoracoscopic surgery still needs further studies.

METHODS

A randomized controlled trial was conducted, enrolling 150 patients who underwent uniportal thoracoscopic lobectomy. The patients were randomly allocated to three groups in a 1:1:1 ratio: the ESPB group (administered 20 ml of 0.5% ropivacaine), the SAPB group (administered 20 ml of 0.5% ropivacaine), and the standard care (control) group. The primary endpoint was the consumption of sufentanil during the first 24 h following surgery. Secondary endpoints assessed the area under the curve (AUC) of pain numerical rating scale (NRS) scores, occurrence of moderate to severe pain, time to initial sufentanil request, and postoperative adverse events.

RESULTS

No significant difference was observed in the consumption of sufentanil during the first 24 h following surgery between the ESPB and SAPB groups (adjusted difference, 1.53 [95% CI, -5.15 to 2.08]). However, in comparison to the control group, both intervention groups demonstrated a significant decrease in sufentanil consumption, with adjusted differences of -9.97 [95% CI, -13.10 to -6.84] for the ESPB group and -12.55 [95% CI, -15.63 to -9.47] for the SAPB group. There were no significant differences in AUC of NRS scores during rest and movement between the ESPB and SAPB groups, with adjusted differences of -7.10 [95% CI, 1.33 to -15.55] for the rest condition and 5.61 [95% CI, -13.23 to 2.01] for the movement condition. At 6 h postoperatively, there were fewer patients with moderate to severe pain in the ESPB group compared with those in the SAPB group (adjusted difference, -1.37% [95% CI, -2.29% to -0.45%]. The time to first sufentanil request significantly differed among the three groups (ESPB vs Control P < 0.01, SAPB vs Control P < 0.01, ESPB vs SAPB P = 0.015).

CONCLUSIONS

In patients undergoing uniportal thoracoscopic lobectomy, although the differences between the two groups are not statistically significant, both the ESPB and SAPB demonstrate effective reduction in postoperative opioid consumption and the need for rescue analgesics compared to the control group. Moreover, the ESPB group experienced a significantly lower incidence of moderate to severe pain at 6 h postoperatively compared to the SAPB group.

TRIAL REGISTRATION

The study was registered in the Chinese Clinical Trial Registry (registration No: ChiCTR1900021695, Date of registration: March 5th, 2019).

The Perioperative Pain Management Bundle is Feasible: Findings From the PAIN OUT Registry

OBJECTIVES

The quality of postoperative pain management is often poor. A "bundle," a small set of evidence-based interventions, is associated with improved outcomes in different settings. We assessed whether staff caring for surgical patients could implement a "Perioperative Pain Management Bundle" and whether this would be associated with improved multidimensional pain-related patient-reported outcomes (PROs).

METHODS

"PAIN OUT," a perioperative pain registry, offers tools for auditing pain-related PROs and obtaining information about perioperative pain management during the first 24 hours after surgery. Staff from 10 hospitals in Serbia used this methodology to collect data at baseline. They then implemented the "Perioperative Pain Management Bundle" into the clinical routine and collected another round of data. The bundle consists of 4 treatment elements: (1) a full daily dose of 1 to 2 nonopioid analgesics (eg, paracetamol and/or nonsteroidal anti-inflammatory drugs), (2) at least 1 type of local/regional anesthesia, (3) pain assessment by staff, and (4) offering patients information about pain management. The primary endpoint was a multidimensional pain composite score (PCS), evaluating pain intensity, interference, and side effects that was compared between patients who received the full bundle versus not.

RESULTS

Implementation of the complete bundle was associated with a significant reduction in the PCS ( P < 0.001, small-medium effect size [ES]). When each treatment element was evaluated independently, nonopioid analgesics were associated with a higher PCS (ie, poorer outcome, and negligible ES), and the other elements were associated with a lower PCS (all negligible small ES). Individual PROs were consistently better in patients receiving the full bundle compared with 0 to 3 elements. The PCS was not associated with the surgical discipline.

DISCUSSION

We report findings from using a bundle approach for perioperative pain management in patients undergoing mixed surgical procedures. Future work will seek strategies to improve the effect.

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.

Following Evidence-Based Recommendations for Perioperative Pain Management after Cesarean Section Is Associated with Better Pain-Related Outcomes: Analysis of Registry Data

Women who have had a Cesarean Section (CS) frequently report severe pain and pain-related interference. One reason for insufficient pain treatment might be inconsistent implementation of evidence-based guidelines. We assessed the association between implementing three elements of care recommended by guidelines for postoperative pain management and pain-related patient-reported outcomes (PROs) in women after CS. The analysis relied on an anonymized dataset of women undergoing CS, retrieved from PAIN OUT. PAIN OUT, an international perioperative pain registry, provides clinicians with treatment assessment methodology and tools for patients to assess multi-dimensional pain-related PROs on the first postoperative day. We examined whether the care included [i] regional anesthesia with a neuraxial opioid OR general anesthesia with wound infiltration or a Transvesus Abdominis Plane block; [ii] at least one non-opioid analgesic at the full daily dose; and [iii] pain assessment and recording. Credit for care was given only if all three elements were administered (= “full”); otherwise, it was “incomplete”. A “Pain Composite Score-total” (PCStotal), evaluating outcomes of pain intensity, pain-related interference with function, and side-effects, was the primary endpoint in the total cohort (women receiving GA and/or RA) or a sub-group of women with RA only. Data from 5182 women was analyzed. “Full” care was administered to 20% of women in the total cohort and to 21% in the RA sub-group. In both groups, the PCStotal was significantly lower compared to “incomplete” care (p < 0.001); this was a small-to-moderate effect size. Administering all three elements of care was associated with better pain-related outcomes after CS. These should be straightforward and inexpensive for integration into routine care after CS. However, even in this group, a high proportion of women reported poor outcomes, indicating that additional work needs to be carried out to close the evidence-practice gap so that women who have undergone CS can be comfortable when caring for themselves and their newborn.

Emulsion-induced polymersomes taming tetrodotoxin for prolonged duration local anesthesia

Injectable local anesthetics that can provide a continuous nerve block approximating the duration of a pain state would be a life-changing solution for patients experiencing post-operative pain or chronic pain. Tetrodotoxin (TTX) is a site 1 sodium channel blocker that is extremely potent compared to clinically used local anesthetics. Challengingly, TTX doses are limited by its associated systemic toxicity, thus shortening the achievable duration of nerve blocks. Here, we explore emulsion-induced polymersomes (EIP) as a drug delivery system to safely use TTX for local anesthesia. By emulsifying hyperbranched polyglycerol-poly (propylene glycol)-hyperbranched polyglycerol (HPG-PPG-HPG) in TTX aqueous solution, HPG-PPG-HPG self-assembled into micrometer-sized polymersomes within seconds. The formed polymersomes have microscopically visible internal aqueous pockets that encapsulate TTX with an encapsulation efficiency of up to 94%. Moreover, the polymersomes are structurally stable, enabling sustained TTX release. In vivo, the freshly prepared EIP/TTX formulation can be directly injected and increased the tolerated dose of TTX in Sprague-Dawley rats to 11.5 μg without causing any TTX-related systemic toxicity. In the presence of the chemical penetration enhancer (CPE) sodium octyl sulfate (SOS), a single perineural injection of EIP/TTX/SOS formulation produced a reliable sciatic nerve block for 22 days with minimal local toxicity.

Celecoxib-tramadol co-crystal in patients with moderate-to-severe pain following bunionectomy with osteotomy: A phase 3, randomized, double-blind, factorial, active- and placebo-controlled trial

BACKGROUND

Celecoxib-tramadol co-crystal (CTC) is a first-in-class analgesic co-crystal of celecoxib and racemic tramadol with an improved pharmacologic profile, conferred by the co-crystal structure, compared with its active constituents administered alone/concomitantly.

AIM

We evaluated CTC in moderate-to-severe acute postoperative pain.

MATERIALS AND METHODS

This randomized, double-blind, factorial, active- and placebo-controlled phase 3 trial (NCT03108482) was conducted at 6 US clinical research centers. Adults with moderate-to-severe acute pain following bunionectomy with osteotomy were randomized to oral CTC (200 mg [112 mg celecoxib/88 mg rac-tramadol hydrochloride] every 12 h), tramadol (50 mg every 6 h), celecoxib (100 mg every 12 h), or placebo for 48 h. Patients, investigators, and personnel were blinded to assignment. The primary endpoint was the 0-48 h sum of pain intensity differences (SPID0-48) in all randomized patients. Pain intensity was assessed on a 0-10 numerical rating scale (NRS). Safety was analyzed in patients who received study medication. Funded by ESTEVE Pharmaceuticals.

RESULTS

In 2017 (March to November), 1323 patients were screened and 637 randomized to CTC (n = 184), tramadol (n = 183), celecoxib (n = 181), or placebo (n = 89). Mean baseline NRS was 6.7 in all active groups. CTC had a significantly greater effect on SPID0-48 (least-squares mean: -139.1 [95% confidence interval: -151.8, -126.5]) than tramadol (-109.1 [-121.7, -96.4]; p < 0.001), celecoxib (-103.7 [-116.4, -91.0]; p < 0.001), or placebo (-74.6 [-92.5, -56.6]; p < 0.001). Total treatment-emergent adverse events (TEAEs) were 358 for CTC and 394 for tramadol. Drug-related TEAEs occurred in 37.7% patients in the CTC group, compared with 48.6% in the tramadol group. There were no serious TEAEs/deaths.

CONCLUSION

CTC provided greater analgesia than comparable daily doses of tramadol and celecoxib, with similar tolerability to tramadol. CTC is approved in the United States.

Percutaneous CT-Guided Cryoneurolysis of the Intercostobrachial Nerve for Management of Postmastectomy Pain Syndrome

PURPOSE

To evaluate the feasibility, safety, and efficacy of intercostobrachial nerve (ICBN) cryoneurolysis for pain control in patients with postmastectomy pain syndrome (PMPS).

MATERIALS AND METHODS

Fourteen patients with PMPS were prospectively enrolled into this clinical trial after a positive response to a diagnostic computed tomography (CT)-guided percutaneous block of the ICBN. Participants subsequently underwent CT-guided percutaneous cryoneurolysis of the same nerve and were observed on postprocedural Days 10, 90, and 180. Pain scores, quality-of-life measurements, and global impression of change values were recorded before the procedure and at each follow-up point using established validated outcome instruments.

RESULTS

Cryoneurolysis of the ICBN was technically successful in all 14 patients. The mean pain decreased significantly by 2.1 points at 10 days (P = .0451), by 2.4 points at 90 days (P = .0084), and by 2.9 points at 180 days (P = .0028) after cryoneurolysis. Pain interference with daily activities decreased significantly by 14.4 points after 10 days (P = .0161), by 16.2 points after 90 days (P = .0071), and by 20.7 points after 180 days (P = .0007). There were no procedure-related complications or adverse events.

CONCLUSIONS

Cryoneurolysis of the ICBN in patients with PMPS was technically feasible and safe and resulted in a significant decrease in postmastectomy pain for up to 6 months in this small cohort.

Intraoperative abobotulinumtoxinA alleviates pain after surgery and improves general wellness in a translational animal model

Pain after surgery remains a significant healthcare challenge. Here, abobotulinumtoxinA (aboBoNT-A, DYSPORT) was assessed in a post-surgical pain model in pigs. Full-skin-muscle incision and retraction surgery on the lower back was followed by intradermal injections of either aboBoNT-A (100, 200, or 400 U/pig), vehicle (saline), or wound infiltration of extended-release bupivacaine. We assessed mechanical sensitivity, distress behaviors, latency to approach the investigator, and wound inflammation/healing for 5-6 days post-surgery. We followed with immunohistochemical analyses of total and cleaved synaptosomal-associated protein 25 kD (SNAP25), glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor protein-1(Iba1), calcitonin gene-related peptide (CGRP) and substance P (SP) in the skin, dorsal root ganglia (DRG) and the spinal cord of 400 U aboBoNT-A- and saline-treated animals. At Day 1, partial reversal of mechanical allodynia in aboBoNT-A groups was followed by a full reversal from Day 3. Reduced distress and normalized approaching responses were observed with aboBoNT-A from 6 h post-surgery. Bupivacaine reversed mechanical allodynia for 24 h after surgery but did not affect distress or approaching responses. In aboBoNT-A-treated animals cleaved SNAP25 was absent in the skin and DRG, but present in the ipsilateral dorsal horn of the spinal cord. In aboBoNT-A- versus saline-treated animals there were significant reductions in GFAP and Iba1 in the spinal cord, but no changes in CGRP and SP. Analgesic efficacy of aboBoNT-A appears to be mediated by its activity on spinal neurons, microglia and astrocytes. Clinical investigation to support the use of aboBoNT-A as an analgesic drug for post-surgical pain, is warranted.

Rethinking the definition of chronic postsurgical pain: composites of patient-reported pain-related outcomes vs pain intensities alone

ABSTRACT

Chronic postsurgical pain (CPSP) is defined by pain intensity and pain-related functional interference. This study included measures of function in a composite score of patient-reported outcomes (PROs) to investigate the incidence of CPSP. Registry data were analyzed for PROs 1 day and 12 months postoperatively. Based on pain intensity and pain-related interference with function, patients were allocated to the groups " CPSPF " (at least moderate pain with interference), " mixed " (milder symptoms), and " no CPSPF ". The incidence of CPSPF was compared with CPSP rates referring to published data. Variables associated with the PRO-12 score (composite PROs at 12 months; numeric rating scale 0-10) were analyzed by linear regression analysis. Of 2319 patients, 8.6%, 32.5%, and 58.9% were allocated to the groups CPSPF , mixed , and no CPSPF , respectively. Exclusion of patients whose pain scores did not increase compared with the preoperative status, resulted in a 3.3% incidence. Of the patients without pre-existing pain, 4.1% had CPSPF. Previously published pain cutoffs of numeric rating scale >0, ≥3, or ≥4, used to define CPSP, produced rates of 37.5%, 9.7%, and 5.7%. Pre-existing chronic pain, preoperative opioid medication, and type of surgery were associated with the PRO-12 score (all P < 0.05). Opioid doses and PROs 24 hours postoperatively improved the fit of the regression model. A more comprehensive assessment of pain and interference resulted in lower CPSP rates than previously reported. Although inclusion of CPSP in the ICD-11 is a welcome step, evaluation of pain characteristics would be helpful in differentiation between CPSPF and continuation of pre-existing chronic pain.

The influence of involving patients in postoperative pain treatment decisions on pain-related patient-reported outcomes: A STROBE-compliant registering observational study

The evidence regarding the influence of allowing patients to participate in postoperative pain treatment decisions on acute pain management is contradictory. This study aimed to identify the role of patient participation in influencing pain-related patient-reported outcomes (PROs). This is a cross-sectional study. The data were provided by PAIN OUT (www.pain-out.eu). A dataset specific to adult Chinese patients undergoing orthopedic surgery was selected. The PROs were assessed on postoperative day 1. The patient participant was assessed using an 11-point scale. Participants who reported >5 were allocated to the "participation" group, and those who reported ≤5 were allocated to the "nonparticipation" group. A 1:1 propensity score matching was conducted. The primary outcome was the desire for more pain treatment. All other items of PROs were the secondary outcomes comprising pain intensity, interference of pain with function, emotional impairment, adverse effects, and other patient perception. From February 2014 to November 2020, 2244 patients from 20 centers were approached, of whom 1804 patients were eligible and 726 pairs were matched. There was no significant difference between the groups in the desire for more pain treatment either before (25.4% vs 28.2%, risk ratio [95% CI]: 0.90 [0.77, 1.05], P = .18) or after matching (26.7% vs 28.8%, risk ratio [95% CI]: 0.93 [0.79, 1.10], P = .43). After matching, patients in the participation group reported significantly better PROs, including pain intensity (less time spent in severe pain [P < .01]), emotional impairment (less anxiety [P < .01]), interference with function (less interference with sleep [P < .01]), adverse effects (less drowsiness [P = .01]), and patient perception (more pain relief [P < .01] and more satisfaction [P < .01]), than the nonparticipation group. Patient participation in pain treatment decisions was associated with improved pain experience but failed to mitigate the desire for more treatment.

Propofol total intravenous anaesthesia versus inhalational anaesthesia for acute postoperative pain in patients with morphine patient-controlled analgesia: a large-scale retrospective study with covariate adjustment

Background

To compare the postoperative analgesic effect of propofol total intravenous anaesthesia (TIVA) versus inhalational anaesthesia (GAS) in patients using morphine patient-controlled analgesia (PCA).

Methods

A retrospective cohort study was performed in a single tertiary university hospital. Adult patients who used PCA morphine after general anaesthesia across 15 types of surgeries were included. Patients who received propofol TIVA were compared to those who had inhalational anaesthesia. Primary outcomes assessed were postoperative numerical rating scale (NRS) pain scores and postoperative opioid consumption.

Results

Data from 4202 patients were analysed. The overall adjusted NRS pain scores were significantly lower in patients who received propofol TIVA at rest (GEE: β estimate of the mean on a 0 to 10 scale = -0.56, 95% CI = (-0.74 to -0.38), p < 0.001; GAS as reference group) and with movement (β estimate = -0.89, 95% CI = (-1.1 to -0.69), p < 0.001) from postoperative days (POD) 1–3. Propofol TIVA was associated with lower overall adjusted postoperative morphine consumption (β estimate = -3.45, 95% CI = (-4.46 to -2.44), p < 0.001). Patients with propofol TIVA had lower adjusted NRS pain scores with movement for hepatobiliary/pancreatic (p < 0.001), upper gastrointestinal (p < 0.001) and urological surgeries (p = 0.005); and less adjusted postoperative morphine consumption for hepatobiliary/pancreatic (p < 0.001), upper gastrointestinal (p = 0.006) and urological surgeries (p = 0.002). There were no differences for other types of surgeries.

Conclusion

Propofol TIVA was associated with statistically significant, but small reduction in pain scores and opioid consumption in patients using PCA morphine. Subgroup analysis suggests clinically meaningful analgesia possibly for hepatobiliary/pancreatic and upper gastrointestinal surgeries.

Trial registration

This study is registered at ClinicalTrials.gov (NCT03875872).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01683-9.

Opioids in acute pain: Towards getting the right balance

Misuse of prescription opioids forced an inevitable response from authorities to intervene with consequences felt by all.In the Australian community one person will die for approximately every 3600 adults prescribed opioids, while in the hospital setting a postoperative patient managed primarily with opioids, as opposed to epidural analgesia, has an additional risk of death as high as between one in 56 to 477.Opioids maintain a valid role in acute pain management when use is reasoned and with full awareness of the harms and how they are to be avoided, such as in those at risk of ongoing use, the opioid naïve, and when opioid-induced ventilatory impairment may occur.Clinicians managing acute pain can focus on assessing pain versus nociception, strategically apply antinociceptive medications and neural blockade when indicated, assess pain with an emphasis on the degree of bothersomeness and functional impairment and, finally, optimise the use of framing and placebo-enhancing communication to minimise reliance on medications.

Pain response to cannabidiol in induced acute nociceptive pain, allodynia, and hyperalgesia by using a model mimicking acute pain in healthy adults in a randomized trial (CANAB I)

ABSTRACT

Preclinical studies have demonstrated the analgesic potential of cannabidiol (CBD). Those suggesting an effect on pain-processing receptors have brought CBD back into focus. This study assessed the effect of CBD on acute pain, hyperalgesia, and allodynia compared with placebo. Twenty healthy volunteers were included in this randomized, placebo-controlled, double-blinded, crossover study assessing pain intensities (using numeric rating scale), secondary hyperalgesia (von Frey filament), and allodynia (dry cotton swab) in a well-established acute pain model with intradermal electrical stimulation. The authors compared the effect of 800-mg orally administered CBD on pain compared with placebo. They further examined the effect on hyperalgesia and allodynia. Cannabidiol whole blood levels were also measured. Pain ratings (mean ± SD) did not differ significantly after CBD application compared with placebo (5.2 ± 0.7 vs 5.3 ± 0.7, P-value 0.928), neither did the areas of hyperalgesia and allodynia differ significantly after CBD application compared with placebo (hyperalgesia 23.9 ± 19.2 cm2 vs 27.4 ± 17.0 cm2, P-value 0.597; allodynia 16.6 ± 13.1 cm2 vs 17.3 ± 14.1 cm2, P-value 0.884). The CBD whole blood level (median, first to third quartile) was 2.0 µg/L (1.5-5.1) 60 minutes and 5.0 µg/L (4.0-10.4) 130 minutes after CBD application. Although the oral application of 800-mg CBD failed to show a significant effect, it is important to focus future research on different dosing, routes of administration, and CBD as a part of multimodal treatment strategies before negating its effects on acute pain.

COMPARATIVE ANALGESIC EFFECTS OF SINGLE-DOSE PREOPERATIVE ADMINISTRATION OF PARACETAMOL (ACETAMINOPHEN) 500 mg PLUS CODEINE 30 mg AND IBUPROFEN 400 mg ON PAIN AFTER THIRD MOLAR SURGERY

BACKGROUND

Efficacy and rapid onset of postsurgical oral pain relief are critical to improve clinical outcomes and reduce the risk of excessive dosing with analgesic drugs.

PURPOSE

To compare analgesic effects of preoperative administration of paracetamol 500 mg plus codeine 30 mg in single-tablet and effervescent formulation to ibuprofen 400 mg, and placebo in the management of moderate to severe postoperative pain after mandibular third molar surgery.

MATERIALS AND METHODS

One hundred twenty healthy outpatients aged 15-29 years undergoing surgical removal of 1 bony impacted mandibular third molar were enrolled in this, single-center, prospective, randomized, triple-blind parallel-group, placebo-controlled, clinical trial. Study participants were randomly assigned to three treatment arms. According to the concealed allocation, each patient 30 minutes before surgery received paracetamol 500 mg plus codeine 30 mg (group APAP/COD), ibuprofen 400 mg (group IBU) or placebo (group PLA). Rescue therapy allowed in the postoperative period was paracetamol 500 mg plus codeine 30 mg in groups APAP/COD and PLA and ibuprofen 400 mg in group IBU. Patients recorded on Numerical Rating Scale-11 (NRS-11) the pain intensity, total number of postoperative-supplement medications and time of the first intake, until 12-hours after surgery and over extra 2 days, RESULTS: Over postoperative 3 days, patients in the APAP/COD group (2.33 ± 1.99) displayed significantly (P< .001) less pain intensity than IBU (3.43 ± 2.47) and placebo (3.57 ± 2.62) groups. The first-day postoperative pain was significantly (P < .001) higher in group PLA than in groups APAP/COD and IBU, but not between the latter 2 groups. However, at 2 hours postdose, the IBU group displayed average pain intensity lower than APAP/COD group (P> .05). On the next 2 days, pain intensity was significantly (P< .001) lower in group APAP/COD than in groups IBU and PLA but failed to reach statistical significance between groups IBU and PLA. Although the time to the first using rescue therapy was longer (445.88 ± 159.96 minute) in group IBU, compared to groups APAP/COD (392.67 ± 138.90 minutes) and PLA (323.00 ± 143.95 minutes), the number of supplemented tablets was significantly higher in group IBU (2.89 ± 2.13) than in groups APAP/COD (1.24 ± 1.79) (P= .001) and PLA (1.53 ± 1.67) (P = .008). No adverse events were registered for all groups.

CONCLUSIONS

Within the limits of the present study, over postoperative 3 days, a statistically significant intensity pain reduction and decreased rescue therapy consumption were recorded in the paracetamol-codeine group than to ibuprofen group. Nevertheless, lower pain intensity at 2 hours postdose and longer time using rescue therapy was found in the ibuprofen group without statistical significance. No adverse events occurred over the studied period.

Analgesic efficacy of naproxen sodium versus hydrocodone/acetaminophen in acute postsurgical dental pain: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

Opioid/acetaminophen combinations may be overly prescribed in many post-surgical situations where a non-steroidal anti-inflammatory drug with equal or greater efficacy, fewer central nervous system side effects, and no risk for opioid abuse could be substituted. We compared a single, non-prescription dose of naproxen sodium 440 mg (NapS) against hydrocodone plus acetaminophen 10/650 mg (HYD+APAP) in post-impaction surgery pain.

METHODS

Single-center, randomized, double-blind, placebo-controlled study in moderate-severe pain after surgical removal of impacted third molars (ClinicalTrials.gov: NCT04307940). Patients (n = 212) received NapS, HYD+APAP, or placebo and were assessed over 12 hours. Primary endpoint: summed pain intensity difference from 0 to 12 hours (SPID_0-12). Secondary endpoints: pain intensity, pain relief, time to rescue medication, duration of pain at least half gone. Others: onset of pain relief, global assessment of treatment, adverse events.

RESULTS

All 221 randomized patients formed the safety population and were included in the intention-to-treat sensitivity analysis. Nine patients discontinued treatment or had protocol violations, and 212 patients were included in the per-protocol, primary efficacy population. Both active treatments were significantly more effective than placebo. NapS was significantly more effective than HYD+APAP regarding SPID_0-12 (p = 0.01; primary endpoint), total pain relief (0-6 and 0-12 hours; p < 0.05), time to rescue medication (p < 0.001), and duration of pain at least half gone (p < 0.001). HYD+APAP was not statistically superior to NapS for any endpoint. More adverse events were reported with HYD+APAP (n = 63) than NapS (n = 2) and placebo (n = 20), including nausea, vomiting, and dizziness.

CONCLUSION

In moderate-to-severe postsurgical dental pain, a single dose of NapS was at least as effective as HYD+APAP in the early hours, significantly more effective at reducing pain intensity and providing greater pain relief over 12 hours, and was better tolerated. When not contraindicated, NapS should be considered a preferred alternative to opioid combinations for acute pain. (ClinicalTrials.gov, Identifier: NCT04307940; https://clinicaltrials.gov/ct2/show/NCT04307940).

Erector spinae plane block vs. peri-articular injection for pain control after arthroscopic shoulder surgery: a randomised controlled trial

Interscalene brachial plexus block is the standard regional analgesic technique for shoulder surgery. Given its adverse effects, alternative techniques have been explored. Reports suggest that the erector spinae plane block may potentially provide effective analgesia following shoulder surgery. However, its analgesic efficacy for shoulder surgery compared with placebo or local anaesthetic infiltration has never been established. We conducted a randomised controlled trial to compare the analgesic efficacy of pre-operative T2 erector spinae plane block with peri-articular infiltration at the end of surgery. Sixty-two patients undergoing arthroscopic shoulder repair were randomly assigned to receive active erector spinae plane block with saline peri-articular injection (n = 31) or active peri-articular injection with saline erector spinae plane block (n = 31) in a blinded double-dummy design. Primary outcome was resting pain score in recovery. Secondary outcomes included pain scores with movement; opioid use; patient satisfaction; adverse effects in hospital; and outcomes at 24 h and 1 month. There was no difference in pain scores in recovery, with a median difference (95%CI) of 0.6 (-1.9-3.1), p = 0.65. Median postoperative oral morphine equivalent utilisation was significantly higher in the erector spinae plane group (21 mg vs. 12 mg; p = 0.028). Itching was observed in 10% of patients who received erector spinae plane block and there was no difference in the incidence of significant nausea and vomiting. Patient satisfaction scores, and pain scores and opioid use at 24 h were similar. At 1 month, six (peri-articular injection) and eight (erector spinae plane block) patients reported persistent pain. Erector spinae plane block was not superior to peri-articular injection for arthroscopic shoulder surgery.

Alpha lipoic acid attenuates evoked and spontaneous pain following surgical skin incision in rats

Our previous studies have implicated CaV3.2 isoform of T-type Ca2+ channels (T-channels) in the development of postsurgical pain. We have also previously established that different T-channel antagonists can alleviate in vivo postsurgical pain. Here we investigated the analgesic potential of another T-channel blocker and endogenous antioxidant molecule, α-lipoic acid (ALA), in a postsurgical pain model in rats. Our in vivo results suggest that single and repetitive intraperitoneal injections of ALA after surgery or preemptively, significantly reduced evoked mechanical hyperalgesia following surgical paw incision. Furthermore, repeated preemptive systemic injections of ALA effectively alleviated spontaneous postsurgical pain as determined by dynamic weight-bearing testing. We expect that our preclinical study may lead to further investigation of analgesic properties and mechanisms of analgesic action of ALA in patients undergoing surgery.

Open-Label Placebo Treatment for Acute Postoperative Pain (OLP-POP Study): Study Protocol of a Randomized Controlled Trial

Introduction: Open-label placebos have been proposed as way of using long recognized analgesic placebo effects in an ethical manner. Recent evidence shows efficacy of open-label placebos for clinical conditions, but there is need for more research on open-label placebos in acute pain. In the treatment of acute postoperative pain, minimization of opioid related side effects remains one of the key challenges. Therefore, this study aims at investigating the potential of adding unconditioned open-label placebos to treatment as usual as a means of reducing opioid consumption and its related side effects in patients with acute postoperative pain. Methods and Analysis: This is the protocol of an ongoing single site randomized controlled trial. The first patient was enrolled in May 2020. In total, 70 patients suffering from acute postoperative pain following dorsal lumbar interbody fusion are randomized to either a treatment as usual group or an experimental intervention group. The treatment as usual group consists of participants receiving a patient-controlled morphine pump. On day 1 and 2 post-surgery, patients in the intervention group receive, in addition to treatment as usual, two open-label placebo injections per day along with an evidence-based treatment rationale explaining the mechanisms of placebos. The primary outcome is measured by means of self-administered morphine during day 1 and 2 post-surgery. Several other outcome measures including pain intensity and adverse events as well as potential predictors of placebo response are assessed. Analysis of covariance will be used to answer the primary research question and additional statistical techniques such as generalized linear mixed models will be applied to model the temporal course of morphine consumption. Discussion: This study will provide valuable insights into the efficacy of open-label placebos in acute pain and will potentially constitute an important step toward the implementation of open-label placebos in the clinical management of acute postoperative pain. In addition, it will shed light on a cost-efficient and patient-centered strategy to reduce opioid consumption and its related side effects, without any loss in pain management efficacy. Ethics and Dissemination: The "Ethikkommission Nordwest- und Zentralschweiz" (BASEC2020-00099) approved the study protocol. Results of the analysis will be submitted for publication in a peer-reviewed journal. Clinical Trial Registration: The study is registered at ClinicalTrials.gov (NCT04339023) and is listed in the Swiss national registry at kofam.ch (SNCTP000003720).

Developing consensus on core outcome domains for assessing effectiveness in perioperative pain management: results of the PROMPT/IMI-PainCare Delphi Meeting

ABSTRACT

Postoperative pain management is still insufficient, leading to major deficits, including patient suffering, impaired surgical recovery, long-term opioid intake, and postsurgical chronic pain. Yet, identifying the best treatment options refers to a heterogeneous outcome assessment in clinical trials, not always reflecting relevant pain-related aspects after surgery and therefore hamper evidence synthesis. Establishing a core outcome set for perioperative pain management of acute pain after surgery may overcome such limitations. An international, stepwise consensus process on outcome domains ("what to measure") for pain management after surgery, eg, after total knee arthroplasty, sternotomy, breast surgery, and surgery related to endometriosis, was performed. The process, guided by a steering committee, involved 9 international stakeholder groups and patient representatives. The face-to-face meeting was prepared by systematic literature searches identifying common outcome domains for each of the 4 surgical procedures and included breakout group sessions, world-café formats, plenary panel discussions, and final voting. The panel finally suggested an overall core outcome set for perioperative pain management with 5 core outcome domains: physical function (for a condition-specific measurement), pain intensity at rest, pain intensity during activity, adverse events, and self-efficacy. Innovative aspects of this work were inclusion of the psychological domain self-efficacy, as well as the specific assessment of pain intensity during activity and physical function recommended to be assessed in a condition-specific manner. The IMI-PROMPT core outcome set seeks to improve assessing efficacy and effectiveness of perioperative pain management in any clinical and observational studies as well as in clinical practice.

A randomised, double-blind study investigating the relationship between early childhood trauma and the rewarding effects of morphine

Experiences of childhood trauma (abuse and neglect) are disproportionately higher in those with opioid use disorder (OUD). Childhood trauma may affect the reinforcing and rewarding properties of opioid drugs and responses to pain, potentially via developmental changes to the endogenous opioid system. This has been supported by preclinical research, yet this has not been investigated in non-addicted humans. Physically healthy participants with either a history of severe childhood trauma or no previous history of childhood trauma attended two sessions where they received either an intramuscular active dose of morphine (0.15 mg/kg) or a very low dose control (0.01 mg/kg) in a randomised, double-blind crossover design. Sessions were held 1 week apart. Participants' physical pain threshold and tolerance were measured pre- and post-drug administration using the cold water pressor test, alongside acute subjective and behavioural responses over 2.5 h. The trauma group reported liking the effects of morphine, feeling more euphoric and wanting more of the drug over the session, as well as feeling less nauseous, dizzy, and dislike of the effects of morphine compared to the non-trauma comparison group. Morphine increased pain threshold and tolerance, yet this did not differ between the groups. Childhood trauma may therefore sensitise individuals to the pleasurable and motivational effects of opioids and reduce sensitivity to the negative effects, providing compelling evidence for individual differences in opioid reward sensitivity. This may explain the link between childhood trauma and vulnerability to OUD, with consequent implications on interventions for OUD, the prescribing of opioids, and reducing stigmas surrounding OUD.

Assessing outcome in postoperative pain trials: are we missing the point? A systematic review of pain-related outcome domains reported in studies early after total knee arthroplasty

ABSTRACT

The management of acute postoperative pain remains suboptimal. Systematic reviews and Cochrane analysis can assist with collating evidence about treatment efficacy, but the results are limited in part by heterogeneity of endpoints in clinical trials. In addition, the chosen endpoints may not be entirely clinically relevant. To investigate the endpoints assessed in perioperative pain trials, we performed a systematic literature review on outcome domains assessing effectiveness of acute pain interventions in trials after total knee arthroplasty. We followed the Cochrane recommendations for systematic reviews, searching PubMed, Cochrane, and Embase, resulting in the screening of 1590 potentially eligible studies. After final inclusion of 295 studies, we identified 11 outcome domains and 45 subdomains/descriptors with the domain "pain"/"pain intensity" most commonly assessed (98.3%), followed by "analgesic consumption" (88.8%) and "side effects" (75.3%). By contrast, "physical function" (53.5%), "satisfaction" (28.8%), and "psychological function" (11.9%) were given much less consideration. The combinations of outcome domains were inhomogeneous throughout the studies, regardless of the type of pain management investigated. In conclusion, we found that there was high variability in outcome domains and inhomogeneous combinations, as well as inconsistent subdomain descriptions and utilization in trials comparing for effectiveness of pain interventions after total knee arthroplasty. This points towards the need for harmonizing outcome domains, eg, by consenting on a core outcome set of domains which are relevant for both stakeholders and patients. Such a core outcome set should include at least 3 domains from 3 different health core areas such as pain intensity, physical function, and one psychological domain.

Tramadol/Dexketoprofen Analgesic Efficacy Compared with Tramadol/Paracetamol in Moderate to Severe Postoperative Acute Pain: Subgroup Analysis of a Randomized, Double-Blind, Parallel Group Trial-DAVID Study

INTRODUCTION

Recently the DAVID study demonstrated the better analgesic efficacy of tramadol hydrochloride/dexketoprofen 75/25 mg (TRAM/DKP) over tramadol hydrochloride/paracetamol 75/650 mg (TRAM/paracetamol) in a model of moderate to severe acute pain following surgical removal of an impacted third molar. The aim of this subpopulation analysis was to gain a deeper understanding of the relationship between baseline pain intensity (PI) level and the effectiveness in pain control of the TRAM/DKP combination in comparison with the TRAM/paracetamol combination. This will further improve and facilitate the accurate design of future acute pain studies for the use of the TRAM/DKP combination.

METHODS

Patients experiencing at least moderate pain, defined as a PI score ≥ 4 in an 11-point numerical rating scale (NRS) were stratified according to NRS-PI at baseline (NRS ≥ 4, 5, 6, 7, or 8) or aggregated in two groups: (i) moderate pain, NRS-PI ≥ 4 to ≤ 6; (ii) severe pain, NRS-PI > 6. Analgesic efficacy was assessed at pre-specified time points by using pain relief (PAR) on a 5-point verbal rating scale (VRS) and PI on an 11-point NRS. The primary endpoint was total PAR over 6 h post-dose (TOTPAR6); secondary endpoints included, among others, the time course of mean PAR and PI scores over 8 h, TOTPAR over 2, 4, and 8 h post-dose, and the sum of PI difference (SPID) over 2, 4, 6, and 8 h. Safety evaluation was based on the incidence, seriousness, intensity, and causal relationship of treatment-emergent adverse events (TEAEs).

RESULTS

The analgesic efficacy evaluated by TOTPAR6 (primary endpoint) remained steady across increasing baseline PI-NRS cutoff groups with TRAM/DKP, but not with TRAM/paracetamol. The study also demonstrated the superiority of TRAM/DKP combination over TRAM/paracetamol in terms of TOTPAR over 2, 4, and 8 h post-dose and SPID at 2, 4, 6, and 8 h post-dose in both baseline PI groups (moderate or severe); similarly, the time course of PAR and PI indicated better efficacy with TRAM/DKP as soon as 30 min and up to 4-6 h. The incidence of adverse drug reactions was not increased in the severe baseline PI group.

CONCLUSION

Overall, the results of this subgroup analysis of the DAVID study confirmed the superiority of the analgesic efficacy of TRAM/DKP vs TRAM/paracetamol, irrespective of the baseline PI.

Multifocal Analysis of Acute Pain After Third Molar Removal

Background: To analyze the pain modulation capacity profile in a Brazilian population, the relationship between opioid receptor (OPRM1) and Catechol-O-methyltransferase (COMT) 1polymorphisms and pain modulation capacity was determined through preoperative pain modulation tests and acute postoperative pain control evaluation, swelling, and trismus in 200 volunteers undergoing lower third molar removal.

Methods: Psychologic and clinical parameters were measured. Patient DNA was sequenced for single nucleotide polymorphisms in OPRM1 and COMT, and the salivary concentration of interleukin (IL)-2 (IL)-6, interferon (IFN)-γ and tumor necrosis factor (TNF)-α was evaluated. Primary outcomes were the influence of all predictors on the fluctuation of pain intensity using a visual analogue scale (VAS), and swelling and trismus on the 2nd and 7th postoperative days. Preoperative pain modulation capacity (CPM), pain catastrophizing scale (PCS), body mass index (BMI), and surgery duration and difficulty were evaluated.

Results: Salivary concentration of IFN-γ and IL-2 as well as the duration of surgery influenced the fluctuation of postoperative pain in the VAS, and in the sum of the differences in pain intensity test at 8, 48, and 96 h. BMI influenced swelling, while both BMI and COMT haplotype influenced trismus on the 2nd postoperative day.

Conclusion: Polymorphisms in COMT, salivary concentrations of IL-2 and IFN-γ, BMI, and duration of surgery were predictors for pain fluctuation, swelling, and trismus on the 2nd day after lower third molar extraction. This therapy was effective in controlling inflammatory symptomatology after lower third molar extraction and ibuprofen was well tolerated by patients.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03169127.

Quantifying noxious-evoked baseline sensitivity in neonates to optimise analgesic trials

Despite the high burden of pain experienced by hospitalised neonates, there are few analgesics with proven efficacy. Testing analgesics in neonates is experimentally and ethically challenging and minimising the number of neonates required to demonstrate efficacy is essential. EEG (electroencephalography)-derived measures of noxious-evoked brain activity can be used to assess analgesic efficacy; however, as variability exists in neonate's responses to painful procedures, large sample sizes are often required. Here, we present an experimental paradigm to account for individual differences in noxious-evoked baseline sensitivity which can be used to improve the design of analgesic trials in neonates. The paradigm is developed and tested across four observational studies using clinical, experimental, and simulated data (92 neonates). We provide evidence of the efficacy of gentle brushing and paracetamol, substantiating the need for randomised controlled trials of these interventions. This work provides an important step towards safe, cost-effective clinical trials of analgesics in neonates.

Determination of equi-analgesic doses of inhaled methoxyflurane versus intravenous fentanyl using the cold pressor test in volunteers: a randomised, double-blinded, placebo-controlled crossover study

Background

Inhaled methoxyflurane for acute pain relief has demonstrated an analgesic effect superior to placebo. Data comparing methoxyflurane to an opioid are needed. The aim of this study was to determine the equi-analgesic doses of inhaled methoxyflurane vs i.v. fentanyl. Both drugs have an onset within minutes and an analgesic effect of 20–30 min.

Methods

Twelve subjects were included in a randomised, double-blinded, placebo-controlled crossover study with four treatments: placebo (NaCl 0.9%), fentanyl 25 μg i.v., fentanyl 50 μg i.v., or inhaled methoxyflurane 3 ml. The subjects reported pain intensity using the verbal numeric rating scale (VNRS) from 0 to 10 during the cold pressor test (CPT). The CPT was performed before (CPT 1), 5 min (CPT 2), and 20 min (CPT 3) after drug administration.

Results

Inhaled methoxyflurane and fentanyl 25 μg reduced VNRS scores significantly compared with placebo at CPT 2 (–1.14 [estimated difference in VNRS between treatment groups with 95% confidence interval {CI}: –1.50 to –0.78]; –1.15 [95% CI: –1.51 to –0.79]; both P<0.001) and CPT 3 (–0.60 [95% CI: –0.96 to –0.24]; –0.84 [95% CI: –1.20 to –0.47]; both P<0.001). There were no significant differences between the two drugs. Methoxyflurane had significantly higher VNRS scores than fentanyl 50 μg at CPT 2 (0.90 [95% CI: 0.54–1.26]; P<0.001) and CPT 3 (0.57 [95% CI: 0.21–0.94]; P<0.001).

Conclusions

Inhaled methoxyflurane 3 ml was equi-analgesic to fentanyl 25 μg i.v. at CPT 2. Both resulted in significantly less pain than placebo. Fentanyl 50 μg i.v. demonstrated analgesia superior to methoxyflurane.

Clinical trial registration

NCT03894800

Towards Better Perioperative Pain Management in Mexico: A Study in a Network of Hospitals Using Quality Improvement Methods from PAIN OUT

Objective

This was a pre–post study in a network of hospitals in Mexico-City, Mexico. Participants developed and implemented Quality Improvement (QI) interventions addressing perioperative pain management.

Methods

PAIN OUT, an international QI and research network, provided tools for web-based auditing and feedback of pain management and patient-reported outcomes (PROs) in the clinical routine. Ward- and patient-level factors were evaluated with multi-level models. Change in proportion of patients reporting worst pain ≥6/10 between project phases was the primary outcome.

Results

Participants created locally adapted resources for teaching and pain management, available to providers in the form of a website and a special issue of a national anesthesia journal. They offered teaching to anesthesiologists, surgeons, including residents, and nurses. Information was offered to patients and families. A total of 2658 patients were audited in 9 hospitals, between July 2016 and December 2018. Participants reported that the project made them aware of the importance of: training in pain management; auditing one’s own patients to learn about PROs and that QI requires collaboration between multi-disciplinary teams. Participants reported being unaware that their patients experienced severe pain and lacked information about pain treatment options. Worst pain decreased significantly between the two project phases, as did PROs related to pain interfering with movement, taking a deep breath/coughing or sleep. The opportunity of patients receiving information about their pain treatment options increased from 44% to 77%.

Conclusions

Patients benefited from improved care and pain-related PROs. Clinicians appreciated gaining increased expertise in perioperative pain management and methods of QI.

Peripheral nerve block anaesthesia and postoperative pain in acute ankle fracture surgery: the AnAnkle randomised trial

BACKGROUND

Peripheral nerve blocks (PNBs) are increasingly popular in acute ankle fracture surgery but rebound pain may outweigh the benefits. The AnAnkle Trial was designed to assess the postoperative pain profile of PNB anaesthesia compared with spinal anaesthesia (SA).

METHODS

The AnAnkle Trial was a randomised, two-centre, blinded outcome analysis trial. Eligible adults booked for primary ankle fracture surgery were randomised to PNB or SA. The PNBs were ultrasound-guided popliteal sciatic and saphenous blocks with ropivacaine and SAs were with hyperbaric bupivacaine. Postoperatively, all subjects received paracetamol, ibuprofen, and patient-controlled i.v. morphine for pain. The primary endpoint was 27 h Pain Intensity and Opioid Consumption (PIOC) score. Secondary endpoints included longitudinal pain scores and morphine consumption separately, and questionnaires on quality of recovery.

RESULTS

This study enrolled 150 subjects, and the PNB success rate was >94%. PIOC was lower with PNB anaesthesia (median, -26.5% vs +54.3%; P<0.001) and the probability of a better PIOC score with PNB than with SA was 74.8% (95% confidence interval, 67.0-82.6). Pain scores and morphine consumption analysed separately also yielded a clear benefit with PNB, despite substantial rebound pain when PNBs subsided. Quality of recovery scores were similar between groups, but 99% having PNB vs 90% having SA would choose the same anaesthesia form again (P=0.03).

CONCLUSIONS

PNB anaesthesia was efficient and provided a superior postoperative pain profile compared with SA for acute ankle fracture surgery, despite potentially intense rebound pain after PNB.

CLINICAL TRIAL REGISTRATION

Clinicaltrialsregister.eu, EudraCT number: 2015-001108-76.

Effects of ibuprofen administration timing on oral surgery pain: A randomized clinical trial

OBJECTIVE

This study aimed to compare the analgesic effect of ibuprofen 400 mg given 30 min before or immediately after third molars surgery under local anaesthesia.

MATERIALS AND METHODS

The single-centre, randomized, split-mouth, triple-blind, clinical trial involved 38 outpatients, for a total of 76 bilateral symmetrical fully bone impacted mandibular third molars. Each patient was undergone to separate surgical sessions for the right and left side, and ibuprofen was randomly administered 30 min before or immediately after the intervention. Study participants recorded pain intensity using Numerical Rating Scale-11, the timing of rescue therapy intake and overall tablets consumption over 3 days.

RESULTS

The overall pain intensity score was lower in the group receiving ibuprofen immediately after (3.13 ± 2.46) than before (3.58 ± 2.40) surgery, with statistically significant differences only on the second and third days. The mean time to the first using rescue therapy was longer in the postoperative (598.33 ± 422.62 min) than in the preoperative (406.25 ± 149.79 min) analgesic treatment group (p = .123). The number of supplemented ibuprofen tablets did not differ (p = .530) between both groups.

CONCLUSIONS

Within the limits of the present study, ibuprofen administration immediately after surgery seemed to be more effective than preoperative administration.