STOP!: a randomised, double-blind, placebo-controlled study of the efficacy and safety of methoxyflurane for the treatment of acute pain

Inhaled methoxyflurane (Penthrox®) as a novel pain relief for outpatient hysteroscopy and other gynaecological procedures

OBJECTIVE

Penthrox® (methoxyflurane) is a convenient, portable, self-administered disposable single-use handheld inhaler licenced as an emergency, rapid-onset, short-acting, analgesic in adult trauma patients. Outpatient hysteroscopy is one of the commonest procedures in contemporary gynecology but it can be associated with significant pain leading to poor patient experience and failed procedures. We evaluated the feasibility and acceptability of Penthrox® in women undergoing outpatient hysteroscopic procedures and its potential efficacy to reduce pain and improve patient experience.

STUDY DESIGN

We conducted a prospective observational cohort study on women undergoing hysteroscopy or other intrauterine procedures, such as coil fitting, endometrial biopsy, polypectomy, endometrial ablation and manual vacuum aspiration in an outpatient setting. Women were offered Penthrox® inhalers for pain control, instructed how to use it and asked to record the intra-procedural pain they expected and actually experienced using a 10 cm Visual Analogue Scale. The acceptability, side effects and ease of use of the Penthrox® device were also recorded.

RESULTS

122/146 (83.6 %) women chose to use Penthrox®. 116 out of the 122 (95.1 %) underwent an intrauterine procedure, including 59 hysteroscopic polypectomies and 34 global endometrial ablations. The average pain expected during the procedure was 6.0 (SD = 2.8) and the pain experienced during the procedure was 5.1 (SD = 2.8). The intended procedure was completed in 117 (96 %) women. Penthrox® was considered easy to use by 118 (97 %) women and 111 (91 %) would use it again, although 22 (18 %) women would prefer general anaesthesia in the future. No adverse events occurred but 88 (72 %) women reported mild, self-limiting side effects.

CONCLUSION

Penthrox® appears safe, feasible and acceptable as a pain relief option during outpatient hysteroscopy and other intrauterine procedures. The effectiveness of Penthrox® should be evaluated against conventional pain control in an adequately powered multicentre randomised controlled trial.

Inhaled analgesics for the treatment of prehospital acute pain-A systematic review

BACKGROUND

Many prehospital emergency patients receive suboptimal treatment for their moderate to severe pain. Various factors may contribute. We aim to systematically review literature pertaining to prehospital emergency adult patients with acute pain and the pain-reducing effects, adverse events (AEs), and safety issues associated with inhaled analgetic agents compared with other prehospital analgesic agents.

METHODS

As part of an initiative from the Scandinavian Society of Anaesthesia and Intensive Care Medicine, we conducted a systematic review (PROSPERO CRD42018114399), applying the PRISMA guidelines, Grading of Recommendations Assessment, Development, and Evaluation (GRADE), and Cochrane methods, searching the Cochrane Library, Epistemonikos, Centre for Reviews and Dissemination, PubMed, and EMBASE databases (updated March 2024). Inclusion criteria were the use of inhaled analgesic agents in adult patients with acute pain in the prehospital emergency care setting. All steps were performed by minimum of two individual researchers. The primary outcome was pain reduction; secondary outcomes were speed of onset, duration of effect, and relevant AEs.

RESULTS

We included seven studies (56,535 patients in total) that compared inhaled agents (methoxyflurane [MF] and nitrous oxide [N2O]) to other drugs or placebo. Study designs were randomized controlled trial (1; n = 60), randomized non-blinded study (1; n = 343), and randomized open-label study (1; n = 270). The remaining were prospective or retrospective observational studies. The evidence according to GRADE was of low or very low quality. No combined meta-analysis was possible. N2O may reduce pain compared to placebo, but not compared to intravenous (IV) paracetamol, and may be less effective compared to morphine and MF. MF may reduce pain compared to paracetamol, ketoprofen, tramadol, and fentanyl. Both agents may be associated with marked but primarily mild AEs.

CONCLUSION

We found low-quality evidence suggesting that both MF and N2O are safe and may have a role in the management of pain in the prehospital setting. There is low-quality evidence to support MF as a short-acting single analgesic or as a bridge to IV access and the administration of other analgesics. There may be occupational health issues regarding the prehospital use of N2O.

Sex and gender reporting in UK emergency medicine trials from 2010 to 2023: a systematic review

BACKGROUND

Female participants are underrepresented in randomised control trials conducted in urgent care settings. Although sex and gender are frequently reported within demographic data, it is less common for primary outcomes to be disaggregated by sex or gender. The aim of this review is to report sex and gender of participants in the primary papers published on research listed on the National Institute of Health and Care Research (NIHR) Trauma and Emergency Care (TEC) portfolio and how these data are presented.

METHODS

This is a systematic review of the published outputs of interventional trials conducted in UK EDs. Interventional trials were eligible to be included in the review if they were registered on the NIHR TEC research portfolio from January 2010, if the primary paper was published before 31 December 2023 and if the research was delivered primarily in the ED. Trials were identified through the NIHR open data platform and the primary papers were identified through specific searches using MedLine, EMBASE and PubMed. The primary objective of the review is to quantify the proportion of sex-disaggregated or gender-disaggregated primary outcomes in clinical trials within UK emergency medicine.

RESULTS

The initial search revealed 169 registered research projects on the NIHR TEC portfolio during the study period, of which 24 met the inclusion criteria. Overall, 76 719 participants were included, of which 31 374 (40%) were female. Only one trial (CRYOSTAT-2) reported a sex-disaggregated analysis of the effect of the intervention on either primary or secondary outcomes, and no sex-based difference in treatment effect was detected.

CONCLUSIONS

Fewer females than males were included in TEC trials from 2010 to 2023. One trial reported the primary outcome stratified by sex. There is significant scope to increase the scientific value of TEC trials to females by funders.

MethOxyfluraNe in InTerventiOnal Radiology (MONITOR): A randomised controlled trial

INTRODUCTION

Procedural sedation and pain management in interventional radiology (IR) are of critical importance to successful outcomes but remain under-researched. Methoxyflurane has been previously used in some minor procedures with several advantages including rapid onset and offset and a good safety profile. The purpose of this study was to evaluate methoxyflurane for procedures in IR.

METHODS

A randomised, double-blind, placebo-controlled trial was performed between October 2021 and November 2022. Patients presenting for portacath insertion, portacath removal or solid organ biopsy were randomised to either methoxyflurane or placebo. Three hundred and fourteen patients were enrolled in total. Patients were supplied with one Penthrox inhaler containing either 3 mL methoxyflurane or placebo. The primary endpoints of the study were change in pain and anxiety scores compared with baseline, measured on a standardised visual analogue scale (VAS) pre-procedure, at 5-min intervals during the procedure and post-procedure. Baselines scores were controlled for in the statistical analysis. Safety analysis was also performed.

RESULTS

One hundred and sixty-nine patients received methoxyflurane and 145 received placebo. Baseline characteristics were similar between the two groups. The methoxyflurane group had lower pain and anxiety scores throughout the procedure (P < 0.001) with 2.5 times less pain (VAS 1.08/10) and 1.6 times less anxiety (VAS 0.97/10) on average. Lower post-procedure pain (mean 0.72 vs 1.44; P < 0.001) and anxiety (mean 0.55 vs 1.13; P = 0.008) were also observed with methoxyflurane. There were no drug or major procedure-related adverse events.

CONCLUSION

The results of this study suggest that methoxyflurane provides safe and effective analgesia and anxiolysis for some procedures in IR.

Analgesic effectiveness of methoxyflurane inhaler during genicular nerve block in knee osteoarthritis: a randomized controlled trial

BACKGROUND

Up to 30% of patients with knee osteoarthritis (KOA) have evidence of sensitization, with a similar proportion experiencing severe pain during procedures. Most patients with KOA are elderly and often develop side effects from intravenous sedation. Our study investigated the effectiveness of a methoxyflurane inhaler combined with local anesthesia in reducing procedural pain from genicular nerve block compared with local anesthesia alone.

METHODS

42 adults with refractory KOA were randomized into two groups. Methoxyflurane group received a self-titrated methoxyflurane inhaler with local anesthesia whereas lidocaine group received local anesthesia only. The primary outcome was pain score on a 0-10 verbal numerical rating scale (VNRS) during the procedure. Secondary outcomes included changes in VNRS and behavioral pain scale (critical care pain observational tool) during the procedure, hemodynamic changes, anxiety level, sedation score, and adverse events.

RESULTS

42 patients with a mean age of 66±12 years participated in this study. There were no significant baseline differences. During the procedure, the methoxyflurane group experienced a significantly greater VNRS pain reduction from baseline (2 (1, 4) vs -1 (-2, 0); p<0.01) and greater VNRS reduction over time (p=0.01) compared with the lidocaine group, with a higher sedation score (p<0.01). Immediately postprocedure, anxiety levels were lower in the methoxyflurane group compared with the lidocaine group (median State-Trait Anxiety Inventory score 21 (IQR 20, 24) vs 27 (23, 29); p=0.02), but the median reduction in anxiety level was not significant (6 (1, 12) vs 5 (0, 14); p=0.61). There were no differences in behavioral pain scores, hemodynamic parameters, recovery or discharge times, and adverse effects between the two groups.

CONCLUSION

A methoxyflurane inhaler combined with local anesthesia provided better procedural pain control than local anesthesia alone with no observable differences in adverse effects. Future studies evaluating the impact of a methoxyflurane inhaler on different types of painful procedures are warranted.

Methoxyflurane analgesia for outpatient hysteroscopy: A double-blind, randomised, controlled trial

BACKGROUND

Despite clinical and economic benefits, pain during outpatient hysteroscopy (OPH) remains a barrier to use. There is a lack of evidence to support routine use of one analgesic over another versus no analgesic.

AIMS

To study the efficacy and safety of methoxyflurane analgesia during OPH.

MATERIALS AND METHODS

A single-centre, randomised, double-blind, placebo-controlled experiment was performed; 90 patients were randomly assigned (1:1). Participants allocated to the treatment group (cases) received 3 mL of methoxyflurane through an inhaler. The control group received a placebo. The primary outcome was a mean difference in pain, via a change in Visual Analog Scale (VAS) score from baseline at diagnostic hysteroscopy. Secondary outcomes were a mean difference in VAS score with any subsequent operative procedures; a mean difference in VAS score at 15 min post-procedure; participant and clinician-reported adverse effects and events; and participant-reported procedure acceptability, adjuvant nitrous oxide (N2O2) use and a composite of 'distress'.

RESULTS

During diagnostic hysteroscopy, there was a mean difference of 11.5 mm/100 (95% confidence interval (CI) 0.08-22.95), P = 0.05, with the lower score in the cases, compared with controls. During subsequent operative procedures, there was a mean difference of 15 mm/100 (95% CI 2.71-28.22), P = 0.02, with the lower pain score in the cases, compared with controls. There was no significant difference in pain 15 min post-procedure, participant- and clinician- reported adverse effects and events, procedure acceptability and the 'distress' composite.

CONCLUSIONS

Methoxyflurane significantly reduced pain during OPH compared with placebo, for diagnostic as well as operative procedures. Furthermore, methoxyflurane was well tolerated, with no adverse events.

Wilderness Medical Society Clinical Practice Guidelines for the Treatment of Acute Pain in Austere Environments: 2024 Update

The Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the management of pain in austere environments. Recommendations are graded based on the quality of supporting evidence as defined by criteria put forth by the American College of Chest Physicians. This is an update of the 2014 version of the "WMS Practice Guidelines for the Treatment of Acute Pain in Remote Environments" published in Wilderness & Environmental Medicine 2014; 25:41-49.

Parenteral, Non-Intravenous Analgesia in Acute Traumatic Pain-A Narrative Review Based on a Systematic Literature Search

Traumatic pain is frequently encountered in emergency care and requires immediate analgesia. Unfortunately, most trauma patients report sustained pain upon arrival at and discharge from the Emergency Department. Obtaining intravenous access to administer analgesics can be time-consuming, leading to treatment delay. This review provides an overview of analgesics with both fast onset and parenteral, non-intravenous routes of administration, and also indicates areas where more research is required.

Penthrox Is an Effective Analgesic but Is It Patient Approved?

Background Penthrox is a handheld inhaler that administers methoxyflurane. Its use is approved for analgesia in moderate-to-severe trauma-related pain in adults in the ED. The literature currently lacks methodologically robust qualitative data on individual patient experiences. Using a structured qualitative study, we set out to address this shortcoming. Methods Five patients were selected as a focus group to identify key themes they felt were important to explore, and these were included in the questionnaire design. We retrospectively identified all uses of Penthrox in the ED from June to August 2021. Qualitative data was gathered using the Trickett short interview method, and responses were grouped into positive and negative descriptors. In addition, quantitative data concerning their experience using the 5-point Likert scale was also gathered. Results A total of 101 participants responded to the questionnaire. Penthrox was utilised mainly for the manipulation of fractures, most commonly those of the ankle and wrist. Around 90% reported an overall satisfaction of ≥ good, and 97% reported the ease of use to be ≥ good. Its analgesic effectiveness was rated as excellent by 52%, and ≥ good by 89%. The most reported side effects were drowsiness (13%) and nausea (7%). The majority reported no side effects (74%). About 94% of the participants said they would take it again if required. An NVivo word cloud (Lumivero, Denver, CO, USA) was created visually, confirming an overall positive experience amongst the patients. Conclusions This study shows that Penthrox is a well-tolerated and user-friendly means of alleviating trauma-related pain in the ED. It highlights the importance of taking into consideration the individual patient journey alongside robust evidence-based data on safety and efficacy for the development of a holistic treatment.

Inhaled methoxyflurane (Penthrox) administration in dentistry as an alternative to nitrous oxide sedation: a review and feasibility study

Methoxyflurane (MOF) as an agent for dental sedation has been used safely in Australasia for decades. The drug is now licensed for relief of pain associated with trauma and is being used during several medical outpatient procedures in the stead of traditional intravenous agents for sedation in the UK. Our aim was to analyse the safety and feasibility of the introduction of MOF as a drug for dental sedation in the UK community setting and assess its environmental impact. A literature review was conducted for available studies and a research audit of medical histories of patients that received nitrous oxide sedation in the previous year was carried out to assess suitability for MOF administration. The published literature shows MOF to be a safe drug for administration in the dental environment and local patients receiving nitrous oxide sedation are medically suitable for MOF administration. The advantages of considering MOF sedation are its environmental benefit and patient acceptability.

Pain Management with Inhalation of Methoxyflurane Administrated by Non-Medical Ski Patrol: A Quality Assessment Study

INTRODUCTION

Pain management can be challenging, especially in remote locations where first responders are not certified health care personnel. In these settings, traditional intravenous administration of analgesics is not feasible. In this study, we explore the feasibility of using methoxyflurane as a first-line analgesic in ski-related traumas, administered by the ski patrol, acting as the municipality physician's aiding personnel.

METHODS

This is a quality assessment of a project aimed at improving pain management in trauma patients at the largest ski resort in Norway. Members of the ski patrol were trained and delegated administration of methoxyflurane on behalf of the municipality physician. Patients > 18 years with ski-related trauma and pain Numeric Rating Scale (NRS) of 6 or more were included. The patients received inhalational methoxyflurane on site, with continued administration during transport. Data were collected by the ski patrol and entered into a quality register.

RESULTS

In total, 53 patients (18 to 76 years, 32 (60%) males) accepted to be registered. The injuries were fractures in 35 (66%), joint luxation in seven (13%), combination of fracture and luxation in seven (13%), and blunt soft tissue damage in four (8%) cases. Median NRS before administration of methoxyflurane was 8 decreasing to median NRS 5 after 5-10 min. The median NRS reduction of 3 (25-75% percentiles 2-5) was significant, p < 0.001. Patients rated the perceived effect as good in 40 (80%) moderate in nine (18%) and no effect in 1 (2%). Side effects were mild: Six patients (11%) experienced dizziness, one patient (2%) was considered drowsy.

CONCLUSIONS

Methoxyflurane is feasible as a first-line analgesic administered by a non-medical ski patrol in a responsibly organized system. Early pain management with inhalation of methoxyflurane provides good perceived effect with mild adverse events and can be of great value in settings where few alternatives for pain management are available.

Haemodynamic effects of methoxyflurane versus fentanyl and placebo in hypovolaemia: a randomised, double-blind crossover study in healthy volunteers

Background

Methoxyflurane is approved for relief of moderate to severe pain in conscious adult trauma patients: it may be self-administrated and is well suited for use in austere environments. Trauma patients may sustain injuries causing occult haemorrhage compromising haemodynamic stability, and it is therefore important to elucidate whether methoxyflurane may adversely affect the haemodynamic response to hypovolaemia.

Methods

In this randomised, double-blinded, placebo-controlled, three-period crossover study, inhaled methoxyflurane 3 ml, i.v. fentanyl 25 μg, and placebo were administered to 15 healthy volunteers exposed to experimental hypovolaemia in the lower body negative pressure model. The primary endpoint was the effect of treatment on changes in cardiac output, while secondary endpoints were changes in stroke volume and mean arterial pressure and time to haemodynamic decompensation during lower body negative pressure.

Results

There were no statistically significant effects of treatment on the changes in cardiac output, stroke volume, or mean arterial pressure during lower body negative pressure. The time to decompensation was longer for methoxyflurane compared with fentanyl (hazard ratio 1.9; 95% confidence interval 0.4-3.4; P=0.010), whereas there was no significant difference to placebo (hazard ratio -1.3; 95% confidence interval -2.8 to 0.23; P=0.117).

Conclusions

The present study does not indicate that methoxyflurane has significant adverse haemodynamic effects in conscious adults experiencing hypovolaemia.

Clinical trial registration

ClinicalTrials.gov (NCT04641949) and EudraCT (2019-004144-29) https://www.clinicaltrialsregister.eu/ctr-search/trial/2019-004144-29/NO.

Real world safety of methoxyflurane analgesia in the emergency setting: a comparative hybrid prospective-retrospective post-authorisation safety study

BACKGROUND

Low-dose analgesic methoxyflurane (Penthrox®) was approved in Europe for emergency relief of moderate to severe pain in conscious adults with trauma in 2015. A comparative post-authorisation safety study (PASS) was conducted to assess the risk of hepatotoxicity and nephrotoxicity with methoxyflurane during routine clinical practice.

METHODS

This was a comparative hybrid prospective-retrospective cohort study. The comparative cohorts consisted of adults who were given methoxyflurane (methoxyflurane cohort) or another analgesic (concurrent cohort) routinely used for moderate to severe trauma and associated pain in the emergency setting (ambulance and Emergency Department) in the UK between December 2016 and November 2018. Hepatic and renal events were captured in the ensuing 12 weeks. A blinded clinical adjudication committee assessed events. A historical comparator cohort (non-concurrent cohort) was identified from patients with fractures in the English Hospital Episode Statistics (HES) accident and emergency database from November 2013 and November 2015 (before commercial launch of methoxyflurane). Hepatic and renal events were captured in the ensuing 12 weeks via linkage with the Clinical Practice Research Datalink (CPRD) and HES hospital admissions databases.

RESULTS

Overall, 1,236, 1,101 and 45,112 patients were analysed in the methoxyflurane, concurrent and non-concurrent comparator cohorts respectively. There was no significant difference in hepatic events between the methoxyflurane and concurrent cohorts (1.9% vs. 3.0%, P = 0.079) or between the methoxyflurane and non-concurrent cohorts (1.9% vs. 2.5%, P = 0.192). Renal events were significantly less common in the methoxyflurane cohort than in the concurrent cohort (2.3% vs. 5.6%, P < 0.001). For methoxyflurane versus non-concurrent cohort the lower occurrence of renal events (2.3% vs. 3.2%, P = 0.070) was not statistically significant. Multivariable adjustment did not change these associations.

CONCLUSIONS

Methoxyflurane administration was not associated with an increased risk of hepatotoxicity or nephrotoxicity compared with other routinely administered analgesics and was associated with a reduced risk of nephrotoxicity compared with other routinely administered analgesics.

TRIAL REGISTRATION

Study registered in the EU PAS Register (ENCEPP/SDPP/13040).

Penthrox enables quicker management of fractures, dislocations and more: learning lessons from expedited care of trauma patients during the COVID-19 pandemic

INTRODUCTION

Methoxyflurane is an historical anaesthetic agent that has undergone a renaissance with the introduction of a smaller dose in a handheld 'Penthrox' device. The benefits of Penthrox include its ease of use, with disposable individual packets, and the need for less monitoring and staff, when compared with deeper sedation. The literature acknowledges its use for analgesia and in the management of anterior shoulder dislocation but in no other procedural orthopaedic circumstance.

METHODS

Following institutional approval, we undertook a retrospective review of all incidences of Penthrox use to facilitate minor procedures within a 2-month period starting 24 March 2020. Time to procedure and success were recorded using the surrogate markers of patient attendance and x-Ray occurrence times.

RESULTS

Some 101 Penthrox doses were given to 89 patients over 97 unique episodes between 24 March and 26 May 2020. No complications were recorded following the use of Penthrox during this period. Patient demographics were explored. Fracture manipulations and casting (n=54) had a 100% success rate in achieving adequate and safe reduction. Joint dislocations (n=34) were treated with varying success. Native elbow dislocations were reduced most successfully (4/4, 100%). Native shoulder dislocations were seen in 17 patients and successful relocation was seen in 11 cases, giving a success rate of 65%.

CONCLUSIONS

This is the first study, outside anterior shoulder dislocations, to report on the efficacy of Penthrox within emergent orthopaedic scenarios. We have demonstrated Penthrox to be a safe tool for helping to manage trauma procedures in the emergency department.

Pain Self-Management with Inhaled Methoxyflurane by Emergency Department Trauma Patients: A Prospective, Interventional, Single-Center Study

The coronavirus disease 2019 (COVID-19) pandemic has led to overcrowding in many emergency departments (EDs). The present single-center, prospective, interventional study (conducted at Bichat University Medical Center (Paris, France)) was designed to assess the impact of self-administered, inhaled, low-dose methoxyflurane on trauma pain in a pre-ED fast-track zone dedicated to the management of lower-acuity non-COVID-19 patients. In the first phase of the study, the control group consisted of patients with mild-to-moderate trauma pain, for whom the triage nurse initiated pain management (based on the World Health Organization (WHO)'s analgesic ladder). In the second phase, the intervention group consisted of similar patients who self-administered methoxyflurane as an adjuvant to the standard analgesic ladder. The primary endpoint was the numerical pain rating scale (NPRS) score (from 0 to 10) recorded at different time points during the patient's care (T0: arrival in the ED, T1: exit from the triage box, T2: in the radiology department, T3: clinical examination, and T4: discharge from the ED). The level of agreement between the NPRS and the WHO analgesic ladder was assessed by the calculation of Cohen's kappa. Pairwise comparisons of continuous variables were performed with Student's t-test or a non-parametric Mann-Whitney U test. Changes over time in the NPRS were analyzed in an analysis of variance (with Scheffe's post hoc test if a pairwise comparison was significant) or a non-parametric Kruskal-Wallis H test. In all, 268 and 252 patients were included in the control and intervention groups, respectively. The two groups had similar characteristics. The level of agreement between the NPRS score and the analgesic ladder was high in both the control and intervention groups (Cohen's kappa: 0.74 and 0.70, respectively). The NPRS score decreased significantly between T0 and T4 in both groups (p < 0.001), but the decrease between T2 and T4 was significantly greater in the intervention group (p < 0.001). The proportion of patients still in pain on discharge was significantly lower in the intervention group than in the control group (p = 0.001). In conclusion, a combination of self-administered methoxyflurane and the WHO analgesic ladder improves pain management in the ED.

Paradoxical increases in anterior cingulate cortex activity during nitrous oxide-induced analgesia reveal a signature of pain affect

The general consensus is that increases in neuronal activity in the anterior cingulate cortex (ACC) contribute to pain's negative affect. Here, using in vivo imaging of neuronal calcium dynamics in mice, we report that nitrous oxide, a general anesthetic that reduces pain affect, paradoxically, increases ACC spontaneous activity. As expected, a noxious stimulus also increased ACC activity. However, as nitrous oxide increases baseline activity, the relative change in activity from pre-stimulus baseline was significantly less than the change in the absence of the general anesthetic. We suggest that this relative change in activity represents a neural signature of the affective pain experience. Furthermore, this signature of pain persists under general anesthesia induced by isoflurane, at concentrations in which the mouse is unresponsive. We suggest that this signature underlies the phenomenon of connected consciousness, in which use of the isolated forelimb technique revealed that pain percepts can persist in anesthetized patients.

A narrative review on pain control interventions for non-surgical pleural procedures

Pleural diseases are common and frequently result in disabling symptoms, impaired health-related quality of life and hospitalisation. Both diagnosis and management often require pleural procedures and despite a variety of pain control strategies available for clinicians to employ, many procedures are still complicated by pain and discomfort. This can interfere with procedure success and can limit patient satisfaction. This review examines the evidence for pain control strategies for people undergoing non-surgical pleural procedures. A systematic literature search was undertaken to identify published studies examining different pain control strategies including pharmacological (sedatives, paravertebral blocks, erector spinae blocks, intrapleural anaesthesia, epidural anaesthesia, local anaesthetic, methoxyflurane, non-steroidal anti-inflammatory drugs [NSAIDs], opioids) and non-pharmacological measures (transcutaneous electric nerve stimulation [TENS], cold application and changes to the intervention or technique). Current literature is limited by heterogeneous study design, small participant numbers and use of different endpoints. Strategies that were more effective than placebo or standard care at improving pain included intrapleural local anaesthesia, paravertebral blocks, NSAIDs, small-bore intercostal catheters (ICC), cold application and TENS. Inhaled methoxyflurane, thoracic epidural anaesthesia and erector spinae blocks may also be useful approaches but require further evaluation to determine their roles in routine non-surgical pleural procedures. Future research should utilise reliable and repeatable study designs and reach consensus in endpoints to allow comparability between findings and thus provide the evidence-base to achieve standardisation of pain management approaches.

Circular External Fixator Removal in the Outpatient Clinic Using Regional Anaesthesia: A Pilot Study of a Novel Approach

Introduction

External fixator (EF) devices are commonly used in the management of complex skeletal trauma, as well as in elective limb reconstruction surgery for the management of congenital and acquired pathology. The subsequent removal of an EF is commonly performed under general anaesthesia in an operating theatre. This practice is resource-intensive and limits the amount of time available for other surgical cases in the operating theatre. We aimed to assess the use of regional anaesthesia as an alternative method of analgesia to facilitate the EF removal in an outpatient setting.

Design and methods

This prospective case series evaluated the first 50 consecutive cases of EF removal in the outpatient clinic between 10/06/22 and 03/02/23. Regional anaesthesia using ultrasound-guided blockade of peripheral nerves was administered using 1% lidocaine due to its rapid onset and short half-life. Patients were assessed for additional analgesia requirements and then were asked to evaluate their experience and perceived pain using the visual analogue scale (VAS).

Results

Fifty patients were included in the study. The mean age was 46.8 years (range 21-85 years). About 54% of the patients were male patients (N = 27). Post-procedure, all patients indicated positive satisfaction ratings, each participant responded as either 'satisfied' (N = 6), 'very satisfied' (N = 24) or 'highly satisfied' (N = 20). In addition, 90% of the participants reported that they would opt for this method of EF removal again in future. The VAS for pain immediately following completion of the procedure was low, with a mean score of 0.36 (range 0-4), where a score of 0 = 'No pain', and 10 = 'worst pain possible'. The median score was 0.

Conclusion

We present the first description of outpatient EF removal using regional anaesthesia, with a prospective case series of 50 fully conscious patients from whom the EF was removed. This novel technique is likely to be cost-effective, reproducible, and safe. This technique reduces the burden of EF removal from an operating list and also improves the patient's experience when compared with other forms of conscious sedation. By eliminating the use of Entonox and methoxyflurane for sedation and analgesia, this technique also demonstrates a method of improving environmental sustainability.

How to cite this article

Williams LM, Stamps G, Peak H, et al. Circular External Fixator Removal in the Outpatient Clinic Using Regional Anaesthesia: A Pilot Study of A Novel Approach. Strategies Trauma Limb Reconstr 2023;18(1):7-11.

Clinical assessment and risk stratification for prehospital use of methoxyflurane versus standard analgesia in adult patients with trauma pain

Oligoanalgesia, the undertreatment of trauma-related pain using standard analgesics in prehospital and emergency departments, has been extensively documented as one of the major challenges affecting the effective treatment of trauma-related pain. When administered in low doses, methoxyflurane has been highlighted by numerous medical works of literature to provide an effective, nonopioid, nonnarcotic treatment alternative to standard analgesics for prehospital and emergency department use. Low-dose methoxyflurane has been associated with fast-pain relief in adult patients manifesting moderate-to-severe pain symptoms. This systematic review and meta-analysis aimed to assess the clinical implication of low-dose methoxyflurane use in prehospital and emergency departments in adult patients with moderate-to-severe trauma-related pain. Moreover, the review aimed at assessing the risk stratification associated with using low-dose methoxyflurane in prehospital and emergency departments. The systematic review and meta-analysis performed a comprehensive search for pertinent literature assessing the implications and risks of using low-dose methoxyflurane in adult patients exhibiting moderate-to-severe trauma-related pain in prehospital settings. A comparison between the use of low-dose methoxyflurane and standard-of-care analgesics, placebo, in prehospital settings was reported in four clinically conducted randomized controlled trials (RCTs). These RCTs included the STOP! trial, InMEDIATE, MEDIATA, and the PenASAP trials. A meta-analysis comparing the time taken to achieve first pain relief on initial treatment of patients with moderate-to-severe trauma-related pain favored the use of low-dose methoxyflurane to the standard-of-care analgesics (mean difference = -6.63, 95% confidence interval = -7.37, -5.09) on time taken to establish effective pain relief. Low-dose methoxyflurane has been associated with superior and faster pain relief in prehospital and emergency departments in adult patients exhibiting moderate-to-severe trauma-related pain compared to other standard analgesics.

Trauma pain management in the emergency department: use of methoxyflurane as a patient-administered analgesic

Evidence suggests that pain is highly prevalent among patients with traumatic injuries who attend emergency departments (EDs), yet accurate assessment and management of patients with acute pain can be challenging in this setting. Effective and rapid pain management is beneficial for patients and can support timely discharge from the ED, which is particularly important in the context of the coronavirus disease 2019 (COVID-19) pandemic. This article describes a service development project that introduced the use of a patient-administered analgesic, methoxyflurane, for patients with traumatic injuries with moderate to severe pain in one ED. The author outlines the benefits and rationale for using methoxyflurane as a first-line analgesic in this patient group and describes the main elements of training sessions for emergency nurses and other ED clinicians in the administration and supervision of patient-administered methoxyflurane.

Evaluation of the effectiveness and costs of inhaled methoxyflurane versus usual analgesia for prehospital injury and trauma: non-randomised clinical study

BACKGROUND

We aimed to investigate clinical benefits and economic costs of inhaled methoxyflurane when used by ambulance staff for prehospital emergency patients with trauma. Comparison is to usual analgesic practice (UAP) in the UK in which patient records were selected if treatment had been with Entonox® or intravenous morphine or intravenous paracetamol.

METHODS

Over a 12-month evaluation period, verbal numerical pain scores (VNPS) were gathered from adults with moderate to severe trauma pain attended by ambulance staff trained in administering and supplied with methoxyflurane. Control VNPS were obtained from ambulance database records of UAP in similar patients for the same period. Statistical modelling enabled comparisons of methoxyflurane to UAP, where we employed an Ordered Probit panel regression model for pain, linked by observational rules to VNPS.

RESULTS

Overall, 96 trained paramedics and technicians from the East Midlands Ambulance Service NHS Trust (EMAS) prepared 510 doses of methoxyflurane for administration to a total of 483 patients. Comparison data extracted from the EMAS database of UAP episodes involved: 753 patients using Entonox®, 802 patients using intravenous morphine, and 278 patients using intravenous paracetamol. Modelling results included demonstration of faster pain relief with inhaled methoxyflurane (all p-values < 0.001). Methoxyflurane's time to achieve maximum pain relief was estimated to be significantly shorter: 26.4 min (95%CI 25.0-27.8) versus Entonox® 44.4 min (95%CI 39.5-49.3); 26.5 min (95%CI 25.0-27.9) versus intravenous morphine 41.8 min (95%CI 38.9-44.7); 26.5 min (95%CI 25.1-28.0) versus intravenous paracetamol 40.8 (95%CI 34.7-46.9). Scenario analyses showed that durations spent in severe pain were significantly less for methoxyflurane. Costing scenarios showed the added benefits of methoxyflurane were achieved at higher cost, eg versus Entonox® the additional cost per treated patient was estimated to be £12.30.

CONCLUSION

When administered to adults with moderate or severe pain due to trauma inhaled methoxyflurane reduced pain more rapidly and to a greater extent than Entonox® and parenteral analgesics. Inclusion of inhaled methoxyflurane to the suite of prehospital analgesics provides a clinically useful addition, but one that is costlier per treated patient.

Usability and effectiveness of inhaled methoxyflurane for prehospital analgesia - a prospective, observational study

Background

Pain relief in the prehospital setting is often insufficient, as the administration of potent intravenous analgesic drugs is mostly reserved to physicians. In Australia, inhaled methoxyflurane has been in routine use by paramedics for decades, but experience in Central European countries is lacking. Thus, we aimed to assess whether user friendliness and effectiveness of inhaled methoxyflurane as sole analgesic match the specific capabilities of local ground and air-based EMS systems in Austria.

Methods

Observational study in adult trauma patients (e.g. dislocations, fracture or low back pain following minor trauma) with moderate to severe pain (numeric rating scale [NRS] ≥4). Included patients received a Penthrop® inhaler containing 3 mL of methoxyflurane (maximum use 30 min). When pain relief was considered insufficient (NRS reduction < 3 after 10 min), intravenous analgesics were administered by an emergency physician. The primary endpoint was effectiveness of methoxyflurane as sole analgesic for transport of patients. Secondary endpoints were user friendliness (EMS personell), time to pain relief, vital parameters, side effects, and satisfaction of patients.

Results

Median numeric pain rating was 8.0 (7.0–8.0) in 109 patients. Sufficient analgesia (reduction of NRS ≥3) was achieved by inhaled methoxyflurane alone in 67 patients (61%). The analgesic effect was progressively better with increasing age. Side effects were frequent (n = 58, 53%) but mild. User satisfaction was scored as very good when pain relief was sufficient, but fair in patients without benefit. Technical problems were observed in 16 cases (14.7%), mainly related to filling of the inhaler. In every fifth use, the fruity smell of methoxyflurane was experienced as unpleasant. No negative effects on vital signs were observed.

Conclusion

In prehospital use, inhaled methoxyflurane as sole analgesic is effective for transport of trauma patients (62%) with moderate to severe pain. Older patients benefit especially from inhaled methoxyflurane. Side effects are mild and vital parameters unaffected. Thus, inhaled methoxyflurane could be a valuable device for non-physician EMS personnel rescue services also in the central Europe region.

[Prehospital Pain Management: Overview and Potential Improvements]

Prehospital Pain Management: Overview and Potential Improvements Abstract. Pain is a frequent issue in the prehospital setting. Rapid and adequate analgesia has a positive effect on the physiological and psychological condition of patients. However, up to 43 % of patients still suffer insufficient analgesia. Several studies have identified some factors that contribute to this problem; these factors can be patient- and intervention-specific or dependent on the staff on duty. In order to improve prehospital analgesia in the future, structural and organizational changes as well as the implementation of new methods and therapies are essential.

The effectiveness and safety of paediatric prehospital pain management: a systematic review

BACKGROUND

Clinically meaningful pain reduction with respect to severity and the adverse events of drugs used in prehospital pain management for children are areas that have not received sufficient attention. The present systematic review therefore aims to perform a comprehensive search of databases to examine the preferable drugs for prehospital pain relief in paediatric patients with acute pain, irrespective of aetiology.

METHODS

The systematic review includes studies from 2000 and up to 2020 that focus on children's prehospital pain management. The study protocol is registered in PROSPERO with registration no. CRD42019126699. Pharmacological pain management using any type of analgesic drug and in all routes of administration was included. The main outcomes were (1) measurable pain reduction (effectiveness) and (2) no occurrence of any serious adverse events. Searches were conducted in PubMed, Medline, Embase, CINAHL, Epistemonikos and Cochrane library. Finally, the risk of bias was assessed using the Joanna Briggs Institute (JBI) checklist and a textual narrative analysis was performed due to the heterogeneity of the results.

RESULTS

The present systematic review on the effectiveness and safety of analgesic drugs in prehospital pain relief in children identified a total of eight articles. Most of the articles reviewed identified analgesic drugs such as fentanyl (intranasal/IV), morphine (IV), methoxyflurane (inhalational) and ketamine (IV/IM). The effects of fentanyl, morphine and methoxyflurane were examined and all of the included analgesic drugs were evaluated as effective. Adverse events of fentanyl, methoxyflurane and ketamine were also reported, although none of these were considered serious.

CONCLUSION

The systematic review revealed that fentanyl, morphine, methoxyflurane and combination drugs are effective analgesic drugs for children in prehospital settings. No serious adverse events were reported following the administration of fentanyl, methoxyflurane and ketamine. Intranasal fentanyl and inhalational methoxyflurane seem to be the preferred drugs for children in pre-hospital settings due to their ease of administration, similar effect and safety profile when compared to other analgesic drugs. However, the level of evidence (LOE) in the included studies was only three or four, and further studies are therefore necessary.

[Volatile anesthetics for prehospital analgesia by paramedics-An overview]

Treatment of acute pain is a central task in emergency medicine. Yet, prehospital pain relief is often insufficient or delayed since the administration of potent intravenous analgesic drugs (such as opioids) is mostly limited to physicians due to legal restrictions or training deficiencies in Germany and Austria. Frequently, prehospitally operating emergency physicians have to be demanded later for anguished patients limiting disposability of physicians for patients who are in a potentially life-threatening condition. Thus, inhaled analgesics could represent an interesting alternative.A mixture of 50% nitrous oxide and 50% oxygen (N₂O, Livopan®) has been available in Germany and Austria for several years; however, prehospital use of Livopan has been merely realized and only one trial has been published. In addition, methoxyflurane (Penthrop®), a volatile anesthetic from the group of the dialkyl esters (2-dichloro-1:1-difluoroethyl-methyl-ester) was approved for the treatment of moderate to severe pain following trauma in adults in many European countries in recent years and was brought onto the market in Austria in 2018. Several in-hospital trials demonstrated high effectiveness in this setting.This article discusses the effects and prehospital areas of application of both substances in the light of the existing literature. We provide a narrative overview of the current study situation and report on a recently performed prehospital application study of methoxyflurane (Penthrop®) from Austria.The need for pressurized gas cylinders for the use of N₂O represents a certain limitation in prehospital use. Furthermore, in certain injuries such as of the inner ear or a pneumothorax N₂O should not be used and the risk of diffusion hypoxemia has to be addressed. Users should be particularly careful and limit the use in alcohol addicts and vegans. The advances of N₂O are that it is odorless, has a fast onset of action, the usability in patients over 1 month old and has stabilizing effects on the circulation. Plenty of literature regarding prehospital as well as in-hospital use of nitrous oxide in emergency, obstetric and pediatric settings show its effectiveness as a single drug as well as in combination with other analgesics, such as paracetamol or various opioids. Its long tradition in Anglo-American countries is also based on its safety and low rate of side effects.Methoxyflurane is easier to store and handle and may be slightly more effective in severe pain after trauma; however, its approval is restricted to adults, where it works significantly better with increasing age, based on the declining minimal alveolar concentration (MAC) of all inhaled anesthetics with increasing age. Furthermore, decades of use of inhaled methoxyflurane in Australia have shown the drug is effective, safe and low in side effects and has a broad spectrum of applications. The use of methoxyflurane is limited in patients with severe hepatic or renal insufficiency and the characteristic odor has been described as unpleasant by some patients. In Europe, three large in-hospital trials showed strong pain relief in trauma patients, even comparable to opioids.Overall, based on the current evidence, the use of nitrous oxide and even more of methoxyflurane may be recommended also for prehospital use by skilled paramedics.

Methoxyflurane in Non-Life-Threatening Traumatic Pain-A Retrospective Observational Study

Pain management is a key issue in prehospital trauma. In Switzerland, paramedics have a large panel of analgesic options. Methoxyflurane was recently introduced into Switzerland, and the goal of this study was to describe both the effect of this medication and the satisfaction of its use. This was a retrospective cohort study, performed in one emergency ambulance service. It included adult patients with traumatic pain and a self-assessment of 3 or more on the visual analogue scale or verbal numerical rating scale. The primary outcome was the reduction in pain between the start of the care and the arrival at the hospital. Secondary outcomes included successful analgesia and staff satisfaction. From December 2018 to 4 June to October 2020, 263 patients were included in the study. Most patients had a low prehospital severity score. The median pain at arrival on site was 8 and the overall decrease in pain observed was 4.2 (95% CI 3.9–4.5). Regarding secondary outcomes, almost 60% had a successful analgesia, and over 70% of paramedics felt satisfied. This study shows a reduction in pain, following methoxyflurane, similar to outcomes in other countries, as well as the attainment of a satisfactory level of pain reduction, according to paramedics, with the advantage of including patients in their own care.

A randomized non-inferiority pilot study on the use of methoxyflurane (Penthrox®) for pain control in the emergency department

Background:

Patients commonly visit the emergency department for pain after musculoskeletal injury, but the problem of oligoanalgesia is prevalent. Methoxyflurane (Penthrox®) is an inhalational analgesic for moderate to severe trauma-associated pain in stable and conscious patients. It is a fast-acting, effective analgesic that can be readily administered via a non-invasive route, making it an attractive agent for managing acute pain in the emergency departments.

Objectives:

The aim was to assess the analgesic efficacy of methoxyflurane in patients with acute traumatic pain by comparing it to ketorolac, a standard analgesic treatment for moderate pain in emergency departments in Hong Kong.

Methods:

This was a single-center, open-label, randomized controlled, parallel-group, non-inferiority pilot study that enrolled adult patients with moderate trauma-associated pain in an emergency department in Hong Kong. Patients were randomized 1:1 to the methoxyflurane group or the ketorolac group. The primary outcome was the change in pain intensity measured by visual analogue scale from baseline to 5, 15, 30, and 60 min after drug administration.

Results:

Twenty patients received methoxyflurane, and twenty patients received ketorolac. There were significant reductions in pain score over 60 min in both groups. The pain reduction at 5 min was significantly greater for the methoxyflurane group (−13.912 mm; 95% confidence interval = −20.008 to −7.817) than for the ketorolac group (−4.888 mm; 95% confidence interval = −10.983 to 1.208), with the treatment effect (−9.025 mm; 95% confidence interval = −17.656 to −0.393; p = 0.041) demonstrating superiority of methoxyflurane. The treatment effect at 15 and 30 min demonstrated non-inferiority of methoxyflurane versus ketorolac.

Conclusion:

Methoxyflurane provided non-inferior analgesia in the first 30 min with a faster onset of action when compared with ketorolac in moderate traumatic pain. It can be considered a non-invasive, rapid-acting, and effective first-line alternative to currently available analgesics for traumatic pain in emergency settings.

Inhaled methoxyflurane for the management of trauma related pain in patients admitted to hospital emergency departments: a randomised, double-blind placebo-controlled trial (PenASAP study)

BACKGROUND

Oligo-analgesia is common in the emergency department (ED). This study aimed at reporting, when initiated by triage nurse, the superior efficacy of inhaled methoxyflurane plus standard of care (m-SoC) analgesia versus placebo plus SoC (p-SoC) for moderate-to-severe trauma-related pain in the hospital ED.

METHODS

A randomised, double-blind, placebo-controlled trial was conducted at eight EDs. Adults with pain score ≥4 (11-point numerical rate scale, NRS) at admission were randomised to receive one or two inhalers containing m-SoC or p-SoC. Primary outcome measure was time until pain relief ≤30 mm, assessed on the 100-mm Visual Analogic Scale (VAS).

RESULTS

A total of 351 patients were analysed (178 m-SoC; 173 p-SoC). Median pain prior to first inhalation was 66 mm, 75% had severe pain (NRS 6-10). Median time to pain relief was 35 min [95% confidence interval (CI), 28-62] for m-SoC versus not reached in p-SoC (92 - not reached) [hazard ratio), 1.93 (1.43-2.60), P < 0.001]. Pain relief was most pronounced in the severe pain subgroup: hazard ratio, 2.5 (1.7-3.7). As SoC, 24 (7%) patients received weak opioids (6 versus 8%), 4 (1%) strong opioid and 44 (13%) escalated to weak or strong opioids (8 versus 17%, respectively, P = 0.02). Most adverse events were of mild (111/147) intensity.

CONCLUSIONS

In this study, we report that methoxyflurane, initiated at triage nurse as part of a multimodal analgesic approach, is effective in achieving pain relief for trauma patients. This effect was particularly pronounced in the severe pain subgroup.

Does Inhaled Methoxyflurane Implement Fast and Efficient Pain Management in Trauma Patients? A Systematic Review and Meta-Analysis

Introduction

Evidence on the use of inhaled methoxyflurane in the management of trauma pain is conflicting and obfuscated. This study aimed to determine the efficacy and safety of inhaled methoxyflurane for trauma pain on the basis of published randomized controlled trials (RCTs).

Methods

RCTs assessing the efficacy of methoxyflurane in adults or adolescents with acute trauma pain published in PubMed, Web of Science, Embase, Cochrane Library, and Google Scholar were searched. The control groups were those that received placebo or standard analgesic treatment (SAT). The primary outcome was the change from baseline in pain scores during the first 30 min of treatment. Secondary outcomes included time to first pain relief, the proportion of patients experiencing pain relief, rescue analgesia rate, the treatment satisfaction of patients and investigators, and the methoxyflurane-related treatment-emergent adverse events (TEAEs).

Results

A total of nine RCTs (1806 patients) were identified. Results revealed that methoxyflurane provided a clinically unimportant benefit by improving the mean difference of change from baseline in pain intensity (from − 0.44 to − 1.23 cm, p < 0.001) at various time points within the first 20 min compared to control treatment. Besides, methoxyflurane decreased the time of onset of pain relief (mean difference − 5.29 min; 95% CI − 6.97 to − 3.62) and the proportion of patients who needed rescue analgesic medication (risk ratio 1.41; 95% CI 1.17–1.70) despite it increasing the risk of non-severe TEAEs (risk ratio 3.09; 95% CI 1.72–5.57). Notably, the benefit of almost all secondary pain-related outcomes was rendered clinically nonsignificant between methoxyflurane and SAT strata besides the time of onset of pain relief. The quality of evidence was low or very low in all outcomes.

Conclusions

In emergency situations without effective therapy, this systematic review and meta-analysis provides low-quality evidence that methoxyflurane can be used as a rapid-acting and effective treatment for acute trauma pain, although its utilization is associated a risk of non-severe TEAEs. However, the current evidence does not support the notion that inhaled methoxyflurane offered superior analgesic efficacy to SAT.

Clinical Trial Number

PROSPERO registration number CRD42020223000.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40122-021-00258-9.

Healthcare resource use and cost implications of low dose methoxyflurane for severe trauma-related pain: a qualitative study

Aims

Management of moderate-to-severe trauma-associated pain is often reported as suboptimal, due in part to limitations associated with frequently used analgesics. Low-dose methoxyflurane (LDM) is an inhaled, non-opioid analgesic, recently approved for emergency relief of moderate-to-severe trauma-associated pain in conscious adults. This study assessed the perspective of healthcare professionals (HCPs) with regard to the time to analgesia and healthcare cost of LDM versus morphine IV, for patients with severe trauma-related pain receiving emergency care in Belgium.

Materials and methods

Interviews and questionnaires were completed by four healthcare HCPs providing emergency care at different hospitals in Belgium. Processes describing analgesic provision in pre-hospital and hospital emergency department (ED) settings were qualitatively mapped and a cost model applied which included reimbursed analgesic costs, time spent by HCPs making analgesic treatment decisions, preparing and administering the analgesic, and post-dose monitoring and management of analgesic-related adverse events (AEs).

Results

LDM was associated with substantial time and costs savings per patient, largely due to no requirement for AE monitoring. Compared with morphine IV, LDM in the hospital ED was associated with a time saving of 4 minutes to analgesic provision (35 vs 39 min) and ≥224 min in total (35 vs ≥259 min; including monitoring and managing AEs). In the pre-hospital setting, LDM was also associated with a time saving of 4 minutes to analgesic provision (21 vs 25 min) and 198 minutes in total. The corresponded total cost savings with LDM vs morphine IV were ≥€27.32 and ≥€17.95 in the ED or prehospital setting, respectively.

Conclusions

The cost model showed that LDM was associated with substantial time and costs savings versus morphine IV for severe trauma-related emergency pain in pre-hospital and hospital ED settings in Belgium.

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

Comparison of inhaled methoxyflurane versus procedural sedation for manipulation and reduction of acute shoulder and elbow dislocation in the emergency department

Introduction:

This paper compares the usage of inhaled methoxyflurane versus traditional procedural sedation and analgesia for manipulation and reduction of acute shoulder dislocation and acute elbow dislocation in the emergency department.

Methods:

This was a retrospective observational study of patients who presented with either acute shoulder dislocation or acute elbow dislocation to an adult tertiary emergency department between 1 April 2018 and 30 September 2019 and underwent manipulation and reduction with either methoxyflurane or procedural sedation and analgesia. Primary outcomes of patients’ length of stay in the emergency department and secondary outcomes of duration of procedure and success of reduction on first attempt for inhaled methoxyflurane were compared against those of procedural sedation and analgesia.

Results:

A total of 192 patients were included in this study; 74 patients underwent reduction with methoxyflurane while 118 patients (85 acute shoulder dislocation and 33 acute elbow dislocation) underwent reduction with procedural sedation and analgesia. The median length of stay in the emergency department was significantly shorter ( P<0.001) for the methoxyflurane group (99 minutes, interquartile range (IQR) 136.8 minutes) versus the procedural sedation and analgesia group (246.5 minutes, IQR 163 minutes). The median duration of procedure in the emergency department was also significantly shorter ( P<0.001) for the methoxyflurane group (16 minutes, IQR 17 minutes) versus the procedural sedation and analgesia group (32 minutes, IQR 40.3 minutes). There was no significant difference in reduction on first attempt between the two groups.

Conclusion:

The use of inhaled methoxyflurane in the manipulation and reduction of acute shoulder dislocation and acute elbow dislocation was associated with a shorter patient length of stay and a shorter duration of procedure, while no significant difference was observed in the success of reduction on first attempt when compared to procedural sedation and analgesia.

[Analgesia for trauma patients in emergency medicine]

Adequate analgesia is one of the most important measures of emergency care in addition to treatment of vital function disorders and, if indicated, should be promptly undertaken; however, a large proportion of emergency patients receive no or only inadequate pain therapy. The numeric rating scale (NRS) is recommended for pain assessment but is not applicable to every group of patients; therefore, vital signs and body language should be included in the assessment. Pain therapy should reduce the NPRS to <5 points. Ketamine and fentanyl, which have an especially rapid onset of action, and also morphine are suitable for analgesia in spontaneously breathing patients. Basic prerequisites for safe and effective analgesia by healthcare professionals are the use of adequate monitoring, the provision of well-defined emergency equipment, and the mastery of emergency procedures. In a structured competence system, paramedics and nursing personnel can perform safe and effective analgesia.

Inhaled methoxyflurane (Penthrox) for analgesia in trauma: a systematic review protocol

BACKGROUND

More than 75% of patients presenting to the Emergency Department are suffering symptoms of pain. Despite this, 67% will not receive any analgesia. Methoxyflurane is a fluorinated hydrocarbon gas which has analgesic properties when inhaled. Penthrox is a methoxyflurane autoinhaler recently licenced in Europe. Its ease of administration, safety, and fast onset of action make it of particular relevance to emergency medicine. Additionally, outside the hospital, it has the advantage of increased temperature stability and portability over current standard care. New evidence of its efficacy is emerging; however, currently, its use in Europe is not widespread. The objective of this study will be to systematically evaluate the evidence on inhaled methoxyflurane to determine if it is a superior analgesia in the acute trauma setting.

METHODS

We designed and registered a study protocol for a systematic review and meta-analysis on randomised controlled trials, comparing inhaled methoxyflurane and either placebo or standard care. A comprehensive search will be conducted from database inception onwards in MEDLINE, Embase, and the Cochrane CENTRAL database, concurrent with a search of the grey literature for other relevant studies, including clinical trial databases. Only randomised controlled trials will be included. No limitations will be imposed on publication status or language of publication. The primary outcome will be mean difference in patient-reported pain at time points within the first 30 min of administration. Secondary outcomes will be mean difference in time to clinically significant pain relief and relative risk of adverse effects. Two reviewers will independently screen all returned studies and collect data. Disagreements will be resolved through discussion or referral to a third reviewer. Individual study methodological quality will be appraised using an appropriate tool. If feasible, we will conduct a random effects meta-analysis; if this is not possible, we will construct a narrative synthesis.

DISCUSSION

This systematic review will summarise the best available evidence and definitively establish if inhaled methoxyflurane is a superior analgesia to standard care in the acute trauma setting. This knowledge will directly impact emergency care in the UK and worldwide and may require amendments to European pain relief guidelines.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020189119 .

Rapid Administration of Methoxyflurane to Patients in the Emergency Department (RAMPED) Study: A Randomized Controlled Trial of Methoxyflurane Versus Standard Care

OBJECTIVE

The objective was to evaluate the effectiveness of methoxyflurane versus standard care for the initial management of severe pain among adult emergency department (ED) patients.

METHODS

This randomized parallel-group open-label phase IV trial of methoxyflurane was conducted in a tertiary hospital ED setting in Australia. Inclusion criteria required adult patients to have an initial pain score ≥ 8 on the 11-point Numerical Rating Scale (NRS). Patients were randomized 1:1 to receive either inhaled methoxyflurane (3 mL) or standard analgesic treatment at ED triage. The primary outcome was the proportion of patients achieving clinically substantial pain reduction, defined as a ≥50% drop in the pain score at 30 minutes. Secondary outcomes included the pain score at multiple time points (15, 30, 60, 90 minutes) and the difference in the proportion of patients achieving a >2-point reduction on the NRS.

RESULTS

There were 120 patients randomized and analyzed between September 4, 2019, and January 16, 2020. The primary outcome was achieved in six (10%) patients in the methoxyflurane arm and three (5%) in the standard care arm (p = 0.49). A higher proportion of patients in the methoxyflurane arm reported a >2-point drop on the NRS at all time points (17% vs. 5% at 15 minutes, 25% vs. 9% at 30 minutes, 30% vs. 10% at 60 minutes, and 33% vs. 13% at 90 minutes). Methoxyflurane use was also associated with lower median pain scores at all time points.

CONCLUSION

Initial management with inhaled methoxyflurane in the ED did not achieve the prespecified substantial reduction in pain, but was associated with clinically significant lower pain scores compared to standard therapy.

Low-Dose Methoxyflurane versus Standard of Care Analgesics for Emergency Trauma Pain: A Systematic Review and Meta-Analysis of Pooled Data

Purpose

Undertreatment of trauma-related pain is common in the pre-hospital and hospital settings owing to barriers to the use of traditional standard of care analgesics. Low-dose methoxyflurane is an inhaled non-opioid analgesic with a rapid onset of pain relief that is approved for emergency relief of moderate-to-severe trauma-related pain in adults. This analysis was performed to compare the efficacy and safety of low-dose methoxyflurane with standard of care analgesics in adults with trauma-related pain.

Methods

A meta-analysis was performed on pooled data from randomized controlled trials identified via a systematic review. The primary endpoint was the pain intensity difference between baseline and various time intervals (5, 10, 15, 20, and 30 minutes) after initiation of treatment.

Results

The pain intensity difference was statistically superior with low-dose methoxyflurane compared with standard of care analgesics (overall estimated treatment effect=11.88, 95% CI=9.75–14.00; P<0.0001). The superiority of low-dose methoxyflurane was demonstrated at 5 minutes after treatment initiation and was maintained across all timepoints. Significantly more patients treated with methoxyflurane achieved response criteria of pain intensity ≤30 mm on a visual analog scale, and relative reductions in pain intensity of ≥30% and ≥50%, compared with patients who received standard of care analgesics. The median time to pain relief was shorter with methoxyflurane than with standard of care analgesics. The findings were consistent in a subgroup of elderly patients (aged ≥65 years).

Conclusion

Methoxyflurane can be considered as an alternative to standard of care analgesics in pre-hospital and hospital settings for treatment of adult patients with acute trauma-related pain.

Military trauma and orthopaedics experience of the UK COVID-19 pandemic: a lesson in versatility and how it can influence our deployed role

The COVID-19 pandemic necessitated unprecedented change within the NHS. Some medical staff have been deployed into unfamiliar roles, while others have been exposed to innovative ways of working. The embedded military Trauma and Orthopaedic (T&O) cadre have been integral to this change. Many of these new skills and ways of working learnt will be transferable to deployed environments. Feedback from the T&O military cadre highlighted key areas of learning as changes in T&O services, use of technology, personal protective equipment, redeployment and training. This paper aims to discuss how these changes were implement and how they could be used within future military roles. The T&O cadre played important roles within their NHS trusts and the skills they learnt will broaden their skills and knowledge for future deployments.

Approaching acute pain in emergency settings; European Society for Emergency Medicine (EUSEM) guidelines-part 2: management and recommendations

BACKGROUND

In Europe, healthcare systems and education, as well as the clinical care and health outcomes of patients, varies across countries. Likewise, the management of acute events for patients also differs, dependent on the emergency care setting, e.g. pre-hospital or emergency department. There are various barriers to adequate pain management and factors common to both settings including lack of knowledge and training, reluctance to give opioids, and concerns about drug-seeking behaviour or abuse. There is no single current standard of care for the treatment of pain in an emergency, with management based on severity of pain, injury and local protocols. Changing practices, attitudes and behaviour can be difficult, and improvements and interventions should be developed with barriers to pain management and the needs of the individual emergency setting in mind.

METHODS

With these principles at the forefront, The European Society for Emergency Medicine (EUSEM) launched a programme-the European Pain Initiative (EPI)-with the aim of providing information, advice, and guidance on acute pain management in emergency settings.

RESULTS AND CONCLUSIONS

This article provides treatment recommendations from recently developed guidelines, based on a review of the literature, current practice across Europe and the clinical expertise of the EPI advisors. The recommendations have been developed, evaluated, and refined for both adults and children (aged ≥ 1 year, ≤ 15 years), with the assumption of timely pain assessment and reassessment and the possibility to implement analgesia. To provide flexibility for use across Europe, options are provided for selection of appropriate pharmacological treatment.

Efficacy, Practicality, and Safety of Inhaled Methoxyflurane in Elderly Patients with Acute Trauma Pain: Subgroup Analysis of a Randomized, Controlled, Multicenter, Open-Label Trial (MEDITA)

Purpose

Acute trauma pain management in the elderly population is a challenge. Inhaled methoxyflurane represents a promising treatment option; however, data in the elderly population are limited.

Patients and Methods

Subgroup, post hoc analysis including 69 patients aged ≥65 years from a randomized, active-controlled, open-label study in the emergency setting. Key inclusion criterion was moderate-to-severe pain (Numerical Rating Scale [NRS] score ≥ 4]) secondary to trauma in a single limb. Patients received inhaled methoxyflurane (3 mL) or standard analgesic treatment (SAT; IV paracetamol 1 g or ketoprofen 100 mg for moderate pain [NRS 4–6] and IV morphine 0.1mg/kg for severe pain [NRS ≥7]). The primary endpoint was the overall change in visual analog scale (VAS) pain intensity from randomization to the next 3, 5, and 10 min. Secondary endpoints included time to onset of pain relief (TOPR), efficacy up to 30 min, judgment of operators and patients, and safety.

Results

Pain reduction over time was similar in both groups. Median TOPR was shorter for methoxyflurane (9 min; 95% CI: 7.8, 10.2 min) than SAT (15 min; 95% CI: 10.2, 19.8 min). In terms of treatment satisfaction, patients and operators rated treatment efficacy and practicality, respectively, as “Excellent” or “Very good” 5.7 times and 3.4 times more frequently than SAT. A similar rate of adverse events (methoxyflurane: 6 events; SAT: 7 events) was recorded, all non-serious. No clinically significant changes in vital signs parameters were observed, and methoxyflurane did not result in cases of bradycardia or hypotension.

Conclusion

In elderly patients with trauma pain, inhaled methoxyflurane shows similar pain relief and safety compared to SAT, offering advantages in terms of onset of effect and user’s satisfaction. Although this analysis presents some methodological limitations, it provides the first specific evidence of the use of inhaled methoxyflurane in the elderly population.

Trial Registration

EudraCT number: 2017-001565-25; Clinicaltrials.gov identifier NCT03585374.

Role of Inhaled Methoxyflurane in the Management of Acute Trauma Pain

Adequate treatment of trauma pain is an integral part of the management of trauma patients, not just for ethical reasons but also because undertreated pain can lead to increased morbidities and worse long-term outcomes. Trauma pain management presents challenges in the pre-hospital setting, particularly in adverse or hostile environments as well as in busy emergency departments (EDs). Inhaled methoxyflurane, administered at analgesic doses via a disposable inhaler, has recently become available in Europe for the emergency treatment of moderate to severe pain in conscious adult trauma patients. A growing body of evidence demonstrates that inhaled methoxyflurane is well tolerated and effective in providing a rapid onset of analgesia. In this paper, we discuss the rationale for methoxyflurane use in trauma pain management, data from clinical trials recently conducted in Europe, its efficacy and safety profile compared to current standard treatments, its place in therapy and organizational impact. We conclude that inhaled methoxyflurane represents an effective treatment option in the different settings where trauma patients require rapid and flexible pain resolution, with potential organizational advantages.

Service Evaluation of Methoxyflurane Versus Standard Care for Overall Management of Patients with Pain Due to Injury

INTRODUCTION

Inhaled methoxyflurane is an analgesic used for the emergency relief of moderate to severe pain in conscious adult patients with trauma and associated pain that is increasingly being used in hospital emergency departments to provide rapid analgesia. It is widely accepted that effective pain relief can facilitate patient care and flow through the emergency department (ED). The main aim of this evaluation was to assess the impact of inhaled methoxyflurane on patient length of stay (LOS) in the ED compared with standard care.

METHODS

Adult patients with moderate to severe trauma pain and Glasgow coma score of 15 were included in the evaluation. Evaluation forms were completed for 79 patients who received methoxyflurane and were matched with 80 patients who received standard care.

RESULTS

Overall the mean time spent in the ED was reduced by 71 min in those patients who were administered methoxyflurane compared with patients who received standard care. Furthermore, analysis of LOS by injury type demonstrated a reduction in ED LOS by 183 min for patients with shoulder dislocation who were treated with methoxyflurane compared with patients who received standard care. There was no reduction in ED LOS for patients with lower limb, hip or pelvic injuries between the two treatment groups.

CONCLUSION

Use of methoxyflurane in adult patients with trauma pain significantly reduced the ED LOS and may potentially improve patient flow through the ED.

Multiple criteria decision analysis approach to consider therapeutic innovations in the emergency department: The methoxyflurane organizational impact in acute trauma pain

BACKGROUND

Acute trauma pain is poorly managed in the emergency department (ED). The reasons are partly organizational: ED crowding and rare trauma care pathways contribute to oligoanalgesia. Anticipating the organizational impact of an innovative care procedure might facilitate the decision-making process and help to optimize pain management.

METHODS

We used a multiple criteria decision analysis (MCDA) approach to consider the organizational impact of methoxyflurane (self-administered) in the ED, introduced alone or supported by a trauma care pathway. A MCDA experiment was designed for this specific context, 8 experts in emergency trauma care pathways (leading physicians and pharmacists working in French urban tertiary hospitals) were recruited. The study involved four steps: (i) Selection of organizational criteria for evaluating the innovation's impact; (ii) assessment of the relative weight of each criterion; (iii) choice of appropriate scenarios for exploring the organizational impact of MEOX under various contexts; and (iv) software-assisted simulation based on pairwise comparisons of the scenarios. The final outcome measure was the expected overall organizational impact of methoxyflurane on a 0-to-100 scale (score >50: positive impact).

RESULTS

Nine organizational criteria were selected. "Mean length of stay in the ED" was the most weighted. Methoxyflurane alone obtained 59 as a total score, with a putative positive impact for eight criteria, and a neutral effect on one. When a trauma care pathway was introduced concomitantly, the impact of methoxyflurane was greater overall (score: 75) and for each individual criterion.

CONCLUSIONS

Our model highlighted the putative positive organizational impact of methoxyflurane in the ED-particularly when supported by a trauma care pathway-and the relevance of expert consensus in this particular pharmacoeconomic context. The MCDA approach could be extended to other research fields and healthcare challenges in emergency medicine.

The use of methoxyflurane (Penthrox®) for procedural analgesia in the emergency department and pre-hospital environment

Background

Methoxyflurane is an inhaled analgesic agent licensed in the United Kingdom for the relief of moderate to severe pain in conscious patients with trauma. Methoxyflurane has been widely used by Australian ambulance services since the 1970s.

Aims

Primary aim: To assess the efficacy of methoxyflurane for procedural analgesia in the emergency department and pre-hospital environment. Secondary aims: to assess the efficacy of methoxyflurane for analgesia in the emergency department and pre-hospital environment; to assess the safety of methoxyflurane as an analgesic.

Method

A literature search of Medline, EMBASE, CINAHL and Cochrane databases was performed. A total of 59 articles were reviewed.

Results

One study using methoxyflurane for procedural analgesia in the emergency department was found. Multiple studies demonstrate the use of methoxyflurane for procedural analgesia for painful procedures outside the emergency department. Compared to other analgesics, methoxyflurane provides adequate analgesia. Overall, methoxyflurane is inferior to fentanyl or morphine, but it provides quicker onset analgesia compared to fentanyl and tramadol. It provides similar analgesia to nitrous oxide. Nephrotoxicity is dose dependent. Used in the analgesic doses, the risk of clinically significant kidney injury is negligible. Rare cases of unpredictable, severe hepatitis are reported.

Discussion

The efficacy of methoxyflurane and its acceptability to patients and clinicians has been shown in a number of studies. As would be expected in any procedural analgesic choice, patient and clinician factors and the procedure planned are all important considerations. Compared to other analgesic agents, methoxyflurane performs favourably with a low chance of adverse events.

Conclusion

Methoxyflurane is an efficacious analgesic agent in the emergency department and pre-hospital environment. It is easily portable and has a rapid onset. Methoxyflurane is suitable for use in procedural analgesia and as a bridging analgesic agent. Risks to the patient from renal or hepatic injury, cardiorespiratory depression or malignant hyperthermia are low.

Comparison of inhalational methoxyflurane (Penthrox®) and intramuscular tramadol for prehospital analgesia

INTRODUCTION

Treatment of pain is an important component of prehospital care. Inhalational analgesia agents have attractive strengths, but there is a paucity of studies comparing these with more conventional agents. We aimed to compare inhalational methoxyflurane and intramuscular (IM) tramadol as first-contact analgesia in the Singapore national ambulance service.

METHODS

Ambulances were randomised to carry either methoxyflurane or IM tramadol for the first six months and crossed over to the other arm after six months. Patients aged ≥ 16 years, with acute pain arising from musculoskeletal trauma with Numerical Rating Scale (NRS) score ≥ 3 were enrolled. Variables included NRS reduction, time variables, adverse effects, Ramsay Sedation Scores, and patient and paramedic satisfaction scores on a Likert scale.

RESULTS

A total of 369 patients were enrolled into this study, but 26 patients were excluded due to missing data. The methoxyflurane arm had a shorter median time taken from arrival at the scene to drug administration (9.0 [interquartile range 6.0-14.0] minutes vs. 11.0 [interquartile range 8.0-15.0] minutes). For patients who achieved reduction in NRS ≥ 3 within 20 minutes, those in the methoxyflurane arm took a shorter time. However, the methoxyflurane (46.7%) arm experienced lower proportion of patients not achieving NRS reduction ≥ 3 when compared to the tramadol (71.6%) arm after over 20 minutes. The methoxyflurane arm had significantly higher paramedic and patient satisfaction scores.

CONCLUSION

For the doses of medication used in this implementation study, methoxyflurane was superior in efficacy, speed of onset and administration, but had more minor adverse effects when compared to IM tramadol.

Inhaled Methoxyflurane versus Intravenous Morphine for Severe Trauma Pain in the Emergency Setting: Subgroup Analysis of MEDITA, a Multicenter, Randomized, Controlled, Open-Label Trial

Purpose

Opioid analgesics remain the cornerstone of treatment for severe trauma pain in the emergency setting, but there are barriers to their use. This post hoc analysis of a previously reported trial (MEDITA) investigated the efficacy and safety of low-dose methoxyflurane versus intravenous (IV) morphine for severe trauma pain.

Patients and Methods

MEDITA was a Phase IIIb, randomized, active-controlled, parallel-group, open-label study in Italian pre-hospital units and emergency departments (EudraCT: 2017-001565-25; NCT03585374). Adult patients (N=272) with moderate-to-severe trauma pain (score ≥4 on the Numerical Rating Scale [NRS]) were randomized 1:1 to inhaled methoxyflurane (3 mL) or standard analgesic treatment (SAT; IV paracetamol 1g or ketoprofen 100mg for moderate pain [NRS 4-6] and IV morphine 0.1mg/kg for severe pain [NRS ≥7]). Analyses were performed for the severe pain subgroup. The primary efficacy variable was the overall change from baseline in visual analog scale (VAS) pain intensity at 3, 5 and 10min post-randomization. Non-inferiority of methoxyflurane versus morphine was concluded if the upper 95% confidence interval (CI) for the treatment difference was <1; superiority was concluded if the upper 95% CI was <0.

Results

Ninety-three patients (methoxyflurane: 49; SAT: 44) were included in the severe pain intention-to-treat population. The reduction in VAS pain intensity over the first 10min was superior for methoxyflurane versus morphine (adjusted mean treatment difference: -5.54mm; 95% CI: -10.49, -0.59mm; p=0.029). Median time to onset of pain relief was 9min for methoxyflurane and 15min for morphine. Patients rated treatment efficacy and physicians rated treatment practicality "Excellent" or "Very good" for more methoxyflurane-treated patients (42.8% and 67.3%) than morphine-treated patients (18.1% and 22.8%). Adverse events, all non-serious, were reported in 20.4% of methoxyflurane-treated patients and in 4.8% of morphine-treated patients.

Conclusion

Methoxyflurane provided superior short-term pain relief to IV morphine in patients with severe trauma pain and offers an effective non-narcotic treatment option.

Non-interventional study evaluating exposure to inhaled, low-dose methoxyflurane experienced by hospital emergency department personnel in France

OBJECTIVES

Low-dose methoxyflurane is a non-opioid, inhaled analgesic administered via the Penthrox inhaler and was recently licensed in Europe for emergency relief of moderate-to-severe trauma-associated pain in conscious adults. This non-interventional study investigated occupational exposure to methoxyflurane in the hospital emergency department (ED) personnel during routine clinical practice.

SETTING AND PARTICIPANTS

The study was conducted in two hospital ED triage rooms in France over a 2-week and 3-week period, respectively. Low-dose methoxyflurane analgesia was self-administered by patients via the inhaler under the supervision of nursing staff, per routine clinical practice. An organic vapour personal badge sampler was attached to the uniform of the nurses working in the treatment rooms throughout an 8-hour shift (total of 140 shifts during the study period). Seven-day ambient air monitoring of each treatment room was also performed. Methoxyflurane levels adsorbed in each badge sampler were measured by a central laboratory. The primary objective was to evaluate methoxyflurane exposure experience by the hospital ED nurses during an 8-hour shift.

RESULTS

In 138 badge samplers, the median (range) concentration of methoxyflurane present following 8-hour nursing shifts was 0.017 (0.008, 0.736) ppm. This level was almost 900-fold lower than the previously reported 8-hour-derived maximal exposure level of 15 ppm; methoxyflurane exposure approaching this threshold was not documented in any badges. There was no correlation between the number of applications of low-dose methoxyflurane administered during a shift (range 0-5) and the vapour exposure measured on the personal badge samplers.

CONCLUSIONS

This study indicates that nurses working in hospital EDs experience very low levels of occupational exposure to methoxyflurane vapour during routine clinical practice. These real-world data can provide reassurance to healthcare providers supervising patients receiving low-dose methoxyflurane analgesia via a Penthrox inhaler; further studies may inform exposure in other hospital ED settings.