A review of the safety and efficacy of inhaled methoxyflurane as an analgesic for outpatient procedures

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.

Inhaled methoxyflurane - an explorable alternative to nitrous oxide?

Nitrous oxide is a widely used and well-established form of inhalation sedation in dentistry. Its properties have a wide margin of safety and allow for anxious, paediatric and adult patients to receive dental treatment with minimal impact upon discharge. Nitrous oxide has drawbacks, however, including its environmental impact and need for specialist equipment. Methoxyflurane is another drug which could prove to be an alternative to nitrous oxide. Methoxyflurane's use has proved popular within emergency medicine in Australia and New Zealand for its potent analgesic effects and recognition of its anxiolytic effect. As a result, its use in invasive outpatient procedures has now become popular. Unfortunately, there is very limited evidence of its use within dentistry as a form of inhalation sedation and analgesic. A wider evidence base should be established, as methoxyflurane could prove to be an effective and environmentally friendly alternative to nitrous oxide.

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).

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.

Literature review on the use of methoxyflurane in the management of pain in cancer-related procedures

INTRODUCTION

Self-administered methoxyflurane, also known as Penthrox, at a sub-anesthetic dose is a short-term, fast-acting, and safe analgesic that may provide suitable pain relief for cancer patients. This review aims to compile the existing evidence on methoxyflurane and its efficacy in reducing pain during cancer-related procedures.

METHODS

A literature search was conducted through OVID Medline and Embase. The search was limited to articles published between 2012 and 2021 and studies were included if they assessed the efficacy of methoxyflurane to reduce pain in cancer-related procedures. All types of cancer were included.

RESULTS

The literature search yielded seven studies published between 2012 and 2021. The studies analyzed assessed methoxyflurane use in prostate biopsy, colonoscopy, removal of brachytherapy rods, and bone marrow biopsy. Various research designs were employed, including three randomized controlled trials, two prospective observational studies, one retrospective, and one non-randomized controlled trial. In all, methoxyflurane has a demonstrated ability to reduce pain in these procedures.

CONCLUSION

In the limited studies available in evaluating the efficacy of methoxyflurane for reducing procedural pain during cancer-related procedures, all have demonstrated clinical equivalency or superiority. Pain relief appears to be equivalent however methoxyflurane overcomes the standard limitations of respiratory sedation and has demonstrated quicker procedural recovery times than traditional sedation methods. The accumulated data to date supports the use of methoxyflurane which can supplement or supplant current methods of analgesia in cancer-related procedures.

Sclerotherapy of lower limb veins: Indications, contraindications and treatment strategies to prevent complications - A consensus document of the International Union of Phlebology-2023

BACKGROUND

Sclerotherapy is a non-invasive procedure commonly used to treat superficial venous disease, vascular malformations and other ectatic vascular lesions. While extremely rare, sclerotherapy may be complicated by serious adverse events.

OBJECTIVES

To categorise contraindications to sclerotherapy based on the available scientific evidence.

METHODS

An international, multi-disciplinary panel of phlebologists reviewed the available scientific evidence and developed consensus where evidence was lacking or limited.

RESULTS

Absolute Contraindications to sclerotherapy where the risk of harm would outweigh any benefits include known hypersensitivity to sclerosing agents; acute venous thromboembolism (VTE); severe neurological or cardiac adverse events complicating a previous sclerotherapy treatment; severe acute systemic illness or infection; and critical limb ischaemia. Relative Contraindications to sclerotherapy where the potential benefits of the proposed treatment would outweigh the risk of harm or the risks may be mitigated by other measures include pregnancy, postpartum and breastfeeding; hypercoagulable states with risk of VTE; risk of neurological adverse events; risk of cardiac adverse events and poorly controlled chronic systemic illness. Conditions and circumstances where Warnings and Precautions should be considered before proceeding with sclerotherapy include risk of cutaneous necrosis or cosmetic complications such as pigmentation and telangiectatic matting; intake of medications such as the oral contraceptive and other exogenous oestrogens, disulfiram and minocycline; and psychosocial factors and psychiatric comorbidities that may increase the risk of adverse events or compromise optimal treatment outcomes.

CONCLUSIONS

Sclerotherapy can achieve safe clinical outcomes provided that (1) patient-related risk factors and in particular all material risks are (1a) adequately identified and the risk benefit ratio is clearly and openly discussed with treatment candidates within a reasonable timeframe prior to the actual procedure; (1b) when an individual is not a suitable candidate for the proposed intervention, conservative treatment options including the option of 'no intervention as a treatment option' are discussed; (1c) complex cases are referred for treatment in controlled and standardised settings and by practitioners with more expertise in the field; (1d) only suitable individuals with no absolute contraindications or those with relative contraindications where the benefits outweigh the risks are offered intervention; (1e) if proceeding with intervention, appropriate prophylactic measures and other risk-mitigating strategies are adopted and appropriate follow-up is organised; and (2) procedure-related risk factors are minimised by ensuring the treating physicians (2a) have adequate training in general phlebology with additional training in duplex ultrasound, procedural phlebology and in particular sclerotherapy; (2b) maintain their knowledge and competency over time and (2c) review and optimise their treatment strategies and techniques on a regular basis to keep up with the ongoing progress in medical technology and contemporary scientific evidence.

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.

Efficacy and Safety of Methoxyflurane for Treatment of Acute Traumatic Pain by EMTs during Alpine Rescue Operations: The "PainDrop" Trial

Background: Treatment of acute traumatic pain is a core task for mountain rescue services. Intravenous access, however, is often difficult, and the vast majority of missions are carried out without a physician at the scene. The spectrum of analgesics available for use by non-physician personnel is limited. Inhaled analgesics, such as methoxyflurane, might prove useful, but currently no data exist on their application by non-physicians in the alpine setting.Methods: This prospective observational alpine field study was conducted over a period of 15 months. Patients suffering traumatic injuries with moderate to severe pain (pain score ≥ 5) after downhill bike accidents in the Tyrol mountains (1,362 m to 2,666 m above sea level) were enrolled. Teams of four mountain rescue service members, one of them a trained EMT, treated the patients with 3 ml of methoxyflurane by inhaler. We measured efficacy as reduction in pain from baseline to 15 minutes after treatment on a numerical rating scale. Safety was assessed by change in vital signs or occurrence of side-effects. Sample-size calculations were based on the efficacy outcome and yielded a need for 20 patients at a power of 0.8.Results: From June 29, 2020 to September 30, 2021, a total of 20 patients (two females; mean age 37 years) were included. The mean initial pain score was 7.2 (SD 1.0) points. After 15 minutes, pain was significantly reduced by a mean of 2.9 (SD 1.4) points. No major adverse events or relevant changes in vital signs were observed.Conclusion: The use of methoxyflurane by EMTs during alpine rescue operations in our study proved to be safe and efficient. We observed no reduction in the efficacy of the inhaler device at moderate altitude.

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.

[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.

'Pain-free TRUS B': a phase 3 double-blind placebo-controlled randomized trial of methoxyflurane with periprostatic local anaesthesia to reduce the discomfort of transrectal ultrasonography-guided prostate biopsy (ANZUP 1501)

Objective

To determine whether the addition of inhaled methoxyflurane to periprostatic infiltration of local anaesthetic (PILA) during transrectal ultrasonography‐guided prostate biopsies (TRUSBs) improved pain and other aspects of the experience.

Patients and Methods

We conducted a multicentre, placebo‐controlled, double‐blind, randomized phase 3 trial, involving 420 men undergoing their first TRUSB. The intervention was PILA plus a patient‐controlled device containing either 3 mL methoxyflurane, or 3 mL 0.9% saline plus one drop of methoxyflurane to preserve blinding. The primary outcome was the pain score (0–10) reported by the participant after 15 min. Secondary outcomes included ratings of other aspects of the biopsy experience, willingness to undergo future biopsies, urologists’ ratings, biopsy completion, and adverse events.

Results

The mean (SE) pain scores 15 min after TRUSB were 2.51 (0.22) in those assigned methoxyflurane vs 2.82 (0.22) for placebo (difference 0.31, 95% confidence interval [CI] −0.75 to 0.14; P = 0.18). Methoxyflurane was associated with better scores for discomfort (difference −0.48, 95% CI −0.92 to −0.03; P = 0.035, adjusted [adj.] P = 0.076), whole experience (difference −0.50, 95% CI −0.92 to −0.08; P = 0.021, adj. P = 0.053), and willingness to undergo repeat biopsies (odds ratio 1.67, 95% CI 1.12–2.49; P = 0.01) than placebo. Methoxyflurane resulted in higher scores for drowsiness (difference +1.64, 95% CI 1.21–2.07; P < 0.001, adj. P < 0.001) and dizziness (difference +1.78, 95% CI 1.31–2.24; P < 0.001, adj. P < 0.001) than placebo. There was no significant difference in the number of ≥ grade 3 adverse events.

Conclusions

We found no evidence that methoxyflurane improved pain scores at 15 min, however, improvements were seen in patient‐reported discomfort, overall experience, and willingness to undergo repeat biopsies.

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

Multiple trauma management in mountain environments - a scoping review : Evidence based guidelines of the International Commission for Mountain Emergency Medicine (ICAR MedCom). Intended for physicians and other advanced life support personnel

Background

Multiple trauma in mountain environments may be associated with increased morbidity and mortality compared to urban environments.

Objective

To provide evidence based guidance to assist rescuers in multiple trauma management in mountain environments.

Eligibility criteria

All articles published on or before September 30th 2019, in all languages, were included. Articles were searched with predefined search terms.

Sources of evidence

PubMed, Cochrane Database of Systematic Reviews and hand searching of relevant studies from the reference list of included articles.

Charting methods

Evidence was searched according to clinically relevant topics and PICO questions.

Results

Two-hundred forty-seven articles met the inclusion criteria. Recommendations were developed and graded according to the evidence-grading system of the American College of Chest Physicians. The manuscript was initially written and discussed by the coauthors. Then it was presented to ICAR MedCom in draft and again in final form for discussion and internal peer review. Finally, in a face-to-face discussion within ICAR MedCom consensus was reached on October 11th 2019, at the ICAR fall meeting in Zakopane, Poland.

Conclusions

Multiple trauma management in mountain environments can be demanding. Safety of the rescuers and the victim has priority. A crABCDE approach, with haemorrhage control first, is central, followed by basic first aid, splinting, immobilisation, analgesia, and insulation. Time for on-site medical treatment must be balanced against the need for rapid transfer to a trauma centre and should be as short as possible. Reduced on-scene times may be achieved with helicopter rescue. Advanced diagnostics (e.g. ultrasound) may be used and treatment continued during transport.

Efficacy of inhaled methoxyflurane for procedural analgesia in paediatric burns: a pilot study

Background: Methoxyflurane (MF), a volatile anaesthetic agent is known for its analgesic properties in sub anaesthetic concentrations. It has been used as an analgesic agent for short procedures in both adults and children in the prehospital setting and in the emergency department. We conducted a pilot study to investigate the use of MF for burn dressing changes in children. Methods: A prospective case series was conducted in the paediatric burns ward amongst children aged 4–9 years. During burns dressing changes MF was administered using a hand-held patient-controlled device. An investigator monitored vital signs together with pain scores, sedation levels and levels of satisfaction of staff. Results: Twelve patients were enrolled for the study. The majority of the burn wounds were classified as partial-thickness wounds. Methoxyflurane was used as the sole agent for analgesia and sedation for the procedure. No major adverse events were noted. Analgesia and sedation levels were sufficient and appropriate respectively for the majority of the patients during the initial exposure of the wound and the application of the new dressing. However, during the scrubbing of the burn wound analgesia and sedation proved insufficient in four and seven of the patients respectively. Conclusion: In our setting the use of MF for inpatient burn wound dressing changes may be insufficient as a sole agent in the paediatric patient. We suggest it may be used as an adjunct to current practice. Further, larger studies are required to delineate the appropriate role MF can play in the paediatric burns setting.

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.

Evolution of hot zone care: MARA

Modern conflict and terrorist events have moved from linear two-dimensional battlespaces into complex, continuously evolving three-dimensional environments. Contested spaces make traditional definitions of zones of response confusing and lead to delays in care. The presence of actual or perceived ongoing threats creates an environment in which the initiation of tactical field care (TFC) may be inappropriate, despite the absence of an immediate risk to life. This risks a 'time and space gap' between care under fire and TFC. Major haemorrhage, airway, respiration, analgesia is proposed as a rethought approach to care in such environments.

Guidelines for the safe use of procedural sedation and analgesia for diagnostic and therapeutic procedures in adults: 2020–2025

Writing guidelines on procedural sedation and analgesia is a formidable and challenging task. There are many disciplines and societies at international level now involved in writing guidelines and we need to be aware of what they see as important in their guidelines. We always need to identify new trends in sedation; for that we need to be involved at international level. Our aim with these guidelines is to provide a guidance for safe sedation practice for all healthcare providers who are involved in sedation practice. In this issue we have added adverse events and record-keeping, accreditation and the importance of simulation training to our recommendations under clinical governance. We would like our sedation practitioners to keep records and report adverse events to our societies, e.g. SOSPOSA, so that we all can benefit from the information we get. It is also crucial that sedation practitioners keep their logbooks and update them regularly – “if it is not written down, it never happened”. All aspects of accreditation remain an important issue and we need to address this urgently. This forms an important part of safe sedation practice, also done at international level, and we need to follow this. The facilities where we work, especially outside the operating theatre, must meet the requirements for safe practice. It is our responsibility to see that this is the case. In the appendices there is a practice appraisal protocol that should be filled in by sedation practitioners doing sedation outside the operating theatre. We do not cover sedation techniques in the guidelines. We believe sedation practitioners must learn the techniques with supervised clinical training. Capnography for sedation outside the operating theatre will become a focus point in future. We are only supposed to be doing ASA I and II patients outside the operating theatre so there may be a feeling we do not need capnography. There is pressure to include capnography under monitoring as a minimum monitoring standard, like pulse oximetry and blood pressure monitoring. Our appendices have been revised with more information on what patients need to know about sedation e.g. an example of a cover letter to the patient. This will include information to the patient, as well as information from the patient. Sedation is today one of the fastest growing areas in anaesthesia care. Our research studies show a low incidence of side-effects, and a high incidence of patient satisfaction. To all our readers we wish you a safe sedation journey.

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.

Quaternary Ammonium Trifluoromethoxide Salts as Stable Sources of Nucleophilic OCF3

The reaction of nucleophilic tertiary amines with trifluoromethyl and pentafluoroethyl methyl ethers provides quaternary ammonium trifluoromethoxide (NR₄OCF₃) and pentafluoroethoxide (NR₄OCF₂CF₃) salts, respectively, in good yields. The new trifluoromethoxide salts disclosed herein are uniquely stable for extended periods of time in both the solid state and in solution, which complements contemporary reagents. Here we describe the preparation of a range of NR₄OCF₃ salts, their long-term stability, and utility in substitution reactions.

Analgesic Efficacy, Practicality and Safety of Inhaled Methoxyflurane Versus Standard Analgesic Treatment for Acute Trauma Pain in the Emergency Setting: A Randomised, Open-Label, Active-Controlled, Multicentre Trial in Italy (MEDITA)

INTRODUCTION

Inhaled low-dose methoxyflurane is approved in Europe for emergency relief of moderate-to-severe trauma-related pain in adults, but data versus active comparators are sparse. The phase IIIb Methoxyflurane in Emergency Department in ITAly (MEDITA) trial investigated the analgesic efficacy, practicality and safety of methoxyflurane versus standard analgesic treatment (SAT) for acute trauma pain.

METHODS

This was a randomised, active-controlled, parallel-group, open-label trial conducted in 15 Italian emergency units. Adults with limb trauma and pain score ≥ 4 on numerical rating scale (NRS) were randomised 1:1 to inhaled methoxyflurane 3 mL or SAT [intravenously administered (IV) morphine 0.1 mg/kg for severe pain (NRS ≥ 7); IV paracetamol 1 g or IV ketoprofen 100 mg for moderate pain (NRS 4-6)]. The primary endpoint was overall change in visual analogue scale (VAS) pain intensity from baseline (time of randomisation) to 3, 5 and 10 min. Non-inferiority and superiority of methoxyflurane versus SAT were concluded if the upper 95% confidence interval (CI) for the treatment comparison (methoxyflurane-SAT) was less than 1 and less than 0, respectively.

RESULTS

Between 8 February 2018 and 8 February 2019, 272 patients were randomised (136 per treatment group). A total of 270 patients (mean age 51 years; 49% male; 34% with severe pain; mean baseline VAS 67 mm) were treated and analysed for efficacy and safety. Superiority of methoxyflurane was demonstrated for moderate-to-severe pain (adjusted mean treatment difference - 5.94 mm; 95% CI - 8.83, - 3.06 mm), moderate pain (- 5.97 mm; 95% CI - 9.55, - 2.39 mm) and severe pain (- 5.54 mm; 95% CI - 10.49, - 0.59 mm). Median onset of pain relief was 9 min for methoxyflurane and 15 min for SAT. Practicality of methoxyflurane treatment was rated "Excellent", "Very Good" or "Good" by 90% of clinicians vs. 64% for SAT. Adverse events (all non-serious) were reported by 17% of methoxyflurane-treated patients and 3% of SAT-treated patients.

CONCLUSION

Methoxyflurane provided superior pain relief to SAT in patients with moderate-to-severe trauma pain and may offer a simple, fast, effective non-opioid treatment option.

TRIAL REGISTRATION

Trial registered with EudraCT (2017-001565-25) on 2 March 2018 and ClinicalTrials.gov (NCT03585374) on 13 July 2018.

FUNDING

Mundipharma Pharmaceuticals S.r.l.

Inhaled Methoxyflurane Provides Greater Analgesia and Faster Onset of Action Versus Standard Analgesia in Patients With Trauma Pain: InMEDIATE: A Randomized Controlled Trial in Emergency Departments

STUDY OBJECTIVE

The objective of the InMEDIATE study was to evaluate the change in intensity of traumatic pain over the first 20 min in adult patients treated with methoxyflurane versus standard analgesic treatment in Spain. This the first randomized, active-controlled, multicenter trial of methoxyflurane in the emergency setting in Europe.

METHODS

This was a randomized, controlled study that enrolled adult patients with acute moderate to severe (score ≥4 on the 11-point Numeric Rating Scale) trauma-associated pain in 14 Spanish emergency departments. Patients were randomized 1:1 to methoxyflurane (up to 2×3 mL) or standard analgesic treatment. Coprimary endpoints were the change from baseline in Numeric Rating Scale pain intensity score during the first 20 minutes of treatment and time to first pain relief.

RESULTS

Three hundred five patients were randomized (methoxyflurane 156; standard analgesic treatment 149). Most patients in the standard analgesic treatment group (70%) received intravenous first-step analgesics and 9.4% of patients were treated with opioids. Mean decrease from baseline in Numeric Rating Scale pain intensity score was greater for methoxyflurane than standard analgesic treatment at all points, with a significant treatment difference overall up to 20 minutes (repeated-measures model 2.47 versus 1.39; treatment difference 1.00; 95% confidence interval 0.84 to 1.32). Median time to first pain relief was significantly shorter for methoxyflurane than standard analgesic treatment (3 versus 10 minutes). Methoxyflurane achieved better patient and clinician ratings for pain control and comfort of treatment than standard analgesic treatment and exceeded patient and clinician expectations of treatment in, respectively, 77% and 72% of cases compared with 38% and 19% for standard analgesic treatment.

CONCLUSION

These results support consideration of methoxyflurane as a nonnarcotic, easy-to-administer, rapid-acting, first-line alternative to currently available analgesic treatments for trauma pain.

BET 1: Green or blue for you? Methoxyflurane (Penthrox) or nitrous oxide/oxygen 50% mixture (Entonox) for the management of acute pain in the ED

A short-cut review of the literature was carried out to establish whether inhaled methoxyflurane (Penthrox) is comparable or superior with a standard inhalational analgesia for the management of acute pain. Only two papers were identified as suitable for inclusion using the reported search strategy. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of the best papers are tabulated. It is concluded that both methods of inhaled analgesia appear to be useful options for acute pain in the ED when compared with placebo. No evidence was found to suggest superiority of methoxypenflurane. International studies directly comparing the use of both drugs for in acute trauma are ongoing and will develop the evidence base.

Penthrox: a breath of PHEC air for the military?

Prehospital analgesia is vital to good clinical care and inhaled methoxyflurane (Penthrox) would be a valuable addition to the armed forces medical armoury. Penthrox would provide strong, fast-acting, self-administered and safe analgesia to patients with moderate to severe injuries. In addition, it would provide an option for strong analgesia which would not be subject to the regulations that govern controlled or accountable drugs which gives it a unique position as the military moves its focus from large enduring operations to small short-term training teams supported by lone combat medics in remote locations across the globe.

Prospective, Multicentre Trial of Methoxyflurane for Acute Trauma-Related Pain in Helicopter Emergency Medical Systems and Hostile Environments: METEORA Protocol

Introduction

The inhalational analgesic low-dose methoxyflurane has been widely used by Australian ambulance services since 1975 and is now approved in Europe for emergency relief of moderate-to-severe trauma-related pain in conscious adult patients. The use of methoxyflurane in hostile environments is of special interest given its portability, ease of use and rapid onset of action. This trial will investigate the efficacy, tolerability and practicality of use of inhaled methoxyflurane in patients with moderate-to-severe trauma-related pain rescued from hostile mountainous environments by the Helicopter Emergency Medical Service (HEMS) in Italy.

Methods

METEORA is a phase IIIb, prospective, single-arm, multicentre trial. Approximately 200 adult patients with a pain score of at least 4 on the numerical rating scale (NRS) due to limb trauma rescued by HEMS will be enrolled. Patients will receive up to 2 × 3 mL methoxyflurane, self-administered by the patient by inhalation under medical supervision. Rescue medication will be permitted if required.

Planned Outcomes

Pain intensity will be measured using a 100-mm visual analogue scale (VAS) at baseline, at 5, 10, 15, 20, 30, 45 and 60 min after the start of methoxyflurane inhalation and when positioning the patient on a spinal board or stretcher; and also using the NRS at enrolment and at 10 min. Use of rescue medication (yes/no) will be recorded. The patient will rate efficacy and the healthcare professional will rate practicality of methoxyflurane treatment at 30 and 60 min using a 5-point Likert scale. Vital signs will be measured at baseline, 10, 30 and 60 min. Assessments after 30 min will only be performed for patients using a second inhaler. Adverse events will be recorded until safety follow-up at 3 ± 1 days. The primary endpoint is the percentage of patients achieving at least 30% improvement from baseline in VAS pain intensity within the first 10 min of methoxyflurane administration.

Trial Registration

EudraCT number: 2017-004601-40.

Funding

Mundipharma Pharmaceuticals, srl.

Plain Language Summary

Plain language summary available for this article.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0816-8) contains supplementary material, which is available to authorized users.

The treatment of pain is an essential part of the management of injured patients. In emergency rescue situations, rapid and effective pain relief can reduce the patient’s stress and discomfort, making it easier to assess, treat and extricate them. Currently available painkillers have limitations such as being slow to work (oral medications), requiring needles (intravenous medications) or prolonged monitoring and observation (e.g. opioids). An inhaled painkiller (methoxyflurane) is now available in Europe for emergency relief of moderate-to-severe pain in conscious adult patients with trauma (injury) and associated pain. Methoxyflurane is administered via a hand-held inhaler, which provides pain relief within 6–10 inhalations and lasts for 25–30 min, on average, when used continuously. The patient can control his/her own level of pain relief and a second inhaler may be used if required. Methoxyflurane has been widely used by Australian ambulance services since 1975 and its effectiveness and safety are well established. Considering its ease of use and rapid action, inhaled methoxyflurane may be useful in emergency situations in remote and hostile environments. A new trial (METEORA) will assess the use of methoxyflurane in 200 patients with limb injuries who are rescued from mountainous environments by the Helicopter Emergency Medical Service (HEMS) in Italy. Patients with moderate-to-severe pain will receive inhaled methoxyflurane under medical supervision. A second inhaler and/or additional pain-relieving medication will be provided if necessary. The trial will assess the reduction in pain intensity and whether additional pain-relieving medication is needed. The practicality of use of methoxyflurane in the emergency rescue situation and any side effects will also be evaluated.

The role of inhaled methoxyflurane in acute pain management

Methoxyflurane is an inhaled analgesic administered via a disposable inhaler which has been used in Australia for over 40 years for the management of pain associated with trauma and for medical procedures in children and adults. Now available in 16 countries worldwide, it is licensed in Europe for moderate to severe pain associated with trauma in conscious adults, although additional applications are being made to widen the range of approved indications. Considering these ongoing developments, we reviewed the available evidence on clinical usage and safety of inhaled analgesic methoxyflurane in trauma pain and in medical procedures in both adults and children. Published data on methoxyflurane in trauma and procedural pain show it to be effective, well tolerated, and highly rated by patients, providing rapid onset of analgesia. Methoxyflurane has a well-established safety profile; adverse events are usually brief and self-limiting, and no clinically significant effects on vital signs or consciousness levels have been reported. Nephrotoxicity previously associated with methoxyflurane at high anesthetic doses is not reported with low analgesic doses. Although two large retrospective comparative studies in the prehospital setting showed inhaled analgesic methoxyflurane to be less effective than intravenous morphine and intranasal fentanyl, this should be balanced against the administration, supervision times, and safety profile of these agents. Given the limitations of currently available analgesic agents in the prehospital and emergency department settings, the ease of use and portability of methoxyflurane combined with its rapid onset of effective pain relief and favorable safety profile make it a useful nonopioid option for pain management. Except for the STOP! study, which formed the basis for approval in trauma pain in Europe, and a few smaller randomized controlled trials (RCTs), much of the available data are observational or retrospective, and further RCTs are currently underway to provide more robust data.