Review article: Efficacy and safety of methoxyflurane analgesia in the emergency department and prehospital setting

The safety of methoxyflurane for emergency pain relief in children and adolescents: a retrospective cohort study

OBJECTIVES

The use of methoxyflurane is becoming increasingly popular in the treatment of pain in an emergency setting, in part due to its ease of administration. However, little is known about the risk of serious adverse events in children and adolescents. The aim of this study was to examine the safety of methoxyflurane in a pediatric population.

METHODS

The study was a retrospective cohort study of pediatric prehospital events using probabilistic linked health data. All ambulance transfers in Western Australia between 1990 and 2016 involving children and adolescent patients were identified. Patients were categorised based on administered analgesia: methoxyflurane, an opioid analgesic, both methoxyflurane and an opioid analgesic, or no analgesic. Hospital and mortality data were linked to transferred patients to identify deaths, adverse drug reactions, liver and kidney toxicity, and re-admissions to hospital following ambulance transfer. Generalized linear models, adjusting for sociodemographic and ambulance transfer characteristics, were used to compare outcomes between children exposed to methoxyflurane and the other three groups.

RESULTS

The study cohort consisted of 37,211 children, including 9,472 patients (25.5%) treated with methoxyflurane alone, 2,764 (7.4%) treated with an opioid analgesic, 1,235 (3.3%) treated with both methoxyflurane and an opioid analgesic, and 23,740 (63.8%) treated with no analgesic. Death in children and adolescents was uncommon, with less than five deaths (<0.1%) observed in the 12 months following treatment with methoxyflurane and no deaths in those treated with both methoxyflurane and an opioid analgesic. Adverse drug reaction was rare (<0.1%) in patients treated with methoxyflurane, as was liver and kidney toxicity with no case observed. At 90-days follow-up, there was no significant difference in hospitalization in patients treated with methoxyflurane and those treated with methoxyflurane and an opioid analgesic (adjusted OR:1.01, 95%CI:0.85-1.21). Compared with methoxyflurane treated patients, patients treated with an opioid analgesic were more likely to be hospitalized (aOR:1.23, 95%CI:1.09-1.39), while patients treated with no analgesic were less likely to be hospitalized (aOR:0.85, 95%CI:0.79-0.92).

CONCLUSIONS

In children and adolescents transported by ambulance, the use of methoxyflurane was not associated with an increased risk of hospitalization, death, serious adverse drug reactions or liver and kidney toxicity.

Climate-conscious sedation: how can we sustainably manage dental anxiety using inhalation sedation?

Climate change represents an urgent global threat. Without action, rising temperatures resulting from human activity will increasingly affect our health and wellbeing through changing patterns of disease, extreme weather events and availability of resources. Expedient decarbonisation of the UK economy is an ambitious goal to which we must all contribute.The NHS aims to be the world's first net-zero health service and reach carbon-neutral status by 2040. Dental services are particularly resource-intensive. Some dental anxiety management techniques have a disproportionately high impact on the environment relative to their usage. Inhalation sedation with nitrous oxide is one such example.Nitrous oxide is a greenhouse gas almost 300 times more potent than carbon dioxide, but its utility to facilitate dental treatment for anxious and vulnerable patients is well-documented. This paper balances the health utility with environmental and social harm of continuing to use nitrous oxide and suggests evidence-based methods we can apply to limit the environmental impact of sedation services.

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.

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.

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.

[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.

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

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.

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.

The difference between a clinical technician and clinical practitioner is in the scope of practice: the need for a bioscience understanding in paramedicine

"Only teach me what I need to know!" This commonly heard refrain is often spoken by allied health students while studying preclinical sciences (physiology, anatomy, pharmacology). Here we use a clinical scenario undertaken by second-year Bachelor of Paramedic Practice students of acute coronary syndrome to demonstrate the difference in clinical decision making when using a clinical reasoning approach to treatment rather than relying exclusively on a practice guidelines approach. We hope to demonstrate that understanding basic bioscience concepts, such as the Frank-Starling mechanism and the anatomy and physiology of the autonomic nervous system, are key to providing good clinical care in response to ambiguous patient symptoms. Students who understand these concepts underlying their patient care guideline will make better clinical decisions and better provide quality of care than students who follow the guideline exclusively. We aim this as a practical demonstration of the value of detailed understanding of human bioscience in allied health education. As health care providers transition from "technician" to "practitioner," the key distinguishing feature of the role is the ability to practice independently, using "best judgment" rather than clinical guidelines (alone). Evidence suggests that complex case management requires detailed bioscience understanding.

Evaluation of pain relief treatment and timelines in emergency care in six European countries and Australia

Purpose

Inadequate relief of pain is common in prehospital and hospital emergency department (ED) settings. We investigated pain treatments and timelines in patients receiving pre-hospital and hospital ED care to provide insight into potential approaches to reduce the burden of trauma-related pain.

Patients and methods

In this observational, retrospective chart review, patients had received emergency care for musculoskeletal trauma injuries and analgesic treatment for moderate-to-severe pain in Belgium, France, Germany, Italy, Spain or Sweden. As inhaled low-dose methoxyflurane (LDM) is used extensively in Australia but was not widely available in Europe at the time of this analysis, data from Australia were collated to provide insight into the potential utility of this analgesic in Europe. The primary endpoint was time to administration of first pain relief treatment following arrival of paramedic/ED care.

Results

Randomly selected physicians (n=189) collated data from 856 patients (Europe: n=585; Australia: n=271) via an online survey. Time to first pain relief treatment varied between countries and was significantly longer across Europe versus Australia (mean [SD] 38.1 [34.7] vs 29.9 [35.5] mins; P=0.0017). Patients from Australia who received LDM experience a shorter mean (SD) time to first pain treatment following arrival of emergency care versus patients who received other analgesics (propensity score matched [n=85] per group: 21.7 [24.2] vs 39.1 [43.0] mins; P=0.0013). Across all countries, mean (SD) time to first analgesic was shorter when treatment was administered by paramedics versus hospital ED staff (15.7 [14.7] vs 49.1 [38.4] mins).

Conclusions

While there was a large variation in analgesia timelines across countries, mean times are shorter in Australia compared with Europe overall. In Australia, use of LDM was associated with a significantly shorter time from emergency assistance to first pain treatment compared with non-LDM treatments. Further studies are needed to investigate the utility of LDM in Europe.

Inhaled methoxyflurane (Penthrox®) versus placebo for injury-associated analgesia in children-the MAGPIE trial (MEOF-002): study protocol for a randomised controlled trial

Background

Pain from injuries is one of the commonest symptoms in children attending emergency departments (EDs), and this is often inadequately treated in both the pre-hospital and ED settings, in part due to challenges of continual assessment and availability of easily administered analgesic options. Pain practices are therefore a key research priority, including within the field of paediatric emergency medicine. Methoxyflurane, delivered via a self-administered Penthrox® inhaler, belongs to the fluorinated hydrocarbon group of volatile anaesthetics and is unique among the group in having analgesic properties at low doses. Despite over 30 years of clinical acute analgesia use, and a large volume of evidence supporting its safety and efficacy, there is a paucity of randomised controlled trial data for Penthrox®.

Methods

This is an international multi-centre randomised, double-blind, placebo-controlled phase III trial assessing the efficacy and safety of methoxyflurane delivered via the Penthrox® inhaler for the management of moderate to severe acute traumatic pain in children and young people aged 6–17 years. Following written informed consent, eligible participants are randomised to self-administer either inhaled methoxyflurane (maximum dose of 2 × 3 ml) or normal saline placebo (maximum dose 2 × 5 ml). Patients, treating clinicians and research nurses are blinded to the treatment. The primary outcome is the change in pain intensity at 15 min after the commencement of treatment, as measured by the Visual Analogue Scale (VAS) or the Wong-Baker FACES® Pain Rating scale, with the latter converted to VAS values. Secondary outcome measures include the number and proportion of responders who achieve a 30% reduction in VAS score compared to baseline, rescue medication requested, time and number of inhalations to first pain relief, global medication performance assessment by the patient, clinician and research nurse, and evaluation of adverse events experienced during treatment and during the subsequent 14 ± 2 days. The primary analysis will be by intention to treat. The total sample size is 110 randomised and treated patients per treatment arm.

Discussion

The Methoxyflurane AnalGesia for Paediatric InjuriEs (MAGPIE) trial will provide efficacy and safety data for methoxyflurane administered via the Penthrox® inhaler, in children and adolescents who present to EDs with moderate to severe injury-related pain.

Trial registration

EudraCT, 2016–004290-41. Registered on 11 April 2017.

ClinicalTrials.gov, NCT03215056. Registered on 12 July 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3511-4) contains supplementary material, which is available to authorized users.

Procedural sedation and analgesia practices in the emergency centre

Introduction

Procedural sedation and analgesia allows the clinician to safely and efficiently administer sedation, analgesia, anxiolysis and sometimes amnesia to facilitate the performance of various procedures in the emergency centre. The aim of this study is to determine current sedation practices, common indications and major obstacles in selected emergency centres across Southern Gauteng, South Africa, with a view to improving future standards and practices.

Methods

This was a prospective, questionnaire based, cross-sectional interview of emergency centre managers or their designee of selected private-sector and public-sector hospitals in Southern Gauteng.

Results

Overall, 17 hospitals completed the interview, nine (53%) public-sector and eight (47%) private-sector hospitals, with 36% of hospitals being aligned to an academic institute. All hospitals performed procedural sedation in their emergency centre. Forty seven percent of managers had between ten and 19 years of clinical experience post internship. Although eleven (64.7%) managers achieved a postgraduate qualification in emergency medicine, only seven (41%) were accredited with a Fellowship of the College of Emergency Medicine (FCEM) qualification and only three (17.7%) centres employed three or more specialists. The majority of centres (52.3%) performed between ten and 30 procedures per month requiring sedation. Staff training in the practice of procedural sedation was mostly obtained internally (52.9%), from in-house seniors. Essential drugs, procedure monitors, resuscitation equipment and protocols were all available in 70.6% of centres.

Conclusion

Although the safe practice and awareness of procedural sedation and analgesia in both public-sector and private-sector emergency centres in Southern Gauteng appears to be on the increase, there is still a need to enhance practitioner training and promote awareness of current local and international trends, protocols and recommendations.

Low-dose methoxyflurane analgesia in adolescent patients with moderate-to-severe trauma pain: a subgroup analysis of the STOP! study

Introduction

The undertreatment of acute pain presents a significant challenge in the Emergency Department. This post hoc subgroup analysis of a previously reported randomized controlled UK study reports the efficacy and safety of low-dose methoxyflurane analgesia in treating adolescent patients with moderate-to-severe trauma pain.

Patients and methods

Three hundred patients (96 in the adolescent subgroup) aged ≥12 years requiring analgesia for acute trauma pain (pain score of 4-7 on the Numerical Rating Scale) at triage were randomized 1:1 to methoxyflurane (up to 6 mL) or placebo (normal saline), both administered using a Penthrox^® inhaler. The patient could request rescue medication (paracetamol/opioids) at any time. The primary endpoint was the change from baseline in visual analog scale (VAS) pain intensity.

Results

Mean VAS pain score for the adolescent subgroup at baseline was ~ 61 mm. Adjusted mean change in VAS pain intensity from baseline to 5, 10, 15, and 20 minutes was -24.5, -28.1, -31.6, and -31.7 mm for methoxyflurane and -14.6, -18.8, -19.2, and -23.7 mm for placebo, with a statistically significant treatment effect in favor of methoxyflurane overall across all four time points (-9.9 mm; 95% CI: -17.4, -2.4 mm; P=0.0104). Median time to first pain relief was significantly shorter with methoxyflurane (1 minute) than placebo (3 minutes, P<0.0001). Pain relief was reported within 1-10 inhalations in 95.7% of methoxyflurane-treated patients and 64.6% of placebo-treated patients. Rescue medication was requested by two (4.3%) methoxyflurane-treated patients and three (6.3%) placebo-treated patients. Over 95% of patients, physicians, and nurses rated methoxyflurane treatment as "Excellent", "Very Good" or "Good" compared with between 64% and 68% for placebo. The incidence of adverse events was higher with methoxyflurane (51%) than placebo (42%), mostly comprising mild/transient dizziness and headache.

Conclusion

This subgroup analysis shows that low-dose inhaled methoxyflurane is a rapid-acting and effective analgesic in adolescent patients presenting with moderate-to-severe trauma pain.

Trial registration

Clinicaltrials.gov identifier: NCT01420159, EudraCT number: 2011-000338-12.

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.

Management of trauma pain in the emergency setting: low-dose methoxyflurane or nitrous oxide? A systematic review and indirect treatment comparison

Background

Low-dose methoxyflurane and nitrous oxide (N₂O; 50:50 with oxygen) are both self-administered, self-titrated, rapid-acting, nonnarcotic, and noninvasive inhalational agents with similar onset times of pain relief. The aim of this review was to compare the clinical efficacy, safety, and tolerability of these analgesics in emergency care.

Materials and methods

A systematic literature search and review according to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were performed using Embase, Medline, the Cochrane Library, several clinical trial registers, and emergency-medicine conference material.

Results

Although both compounds have been used for many years in emergency care, the search found only a few controlled studies and no head-to-head trials performed in this setting. Two double-blind, randomized studies comparing their respective study medication (low-dose methoxyflurane or N₂O) to placebo were identified that could be compared in an indirect approach by using placebo as a bridging comparator. Both agents provided rapid pain relief to trauma patients, with no significant differences between them; both treatments were generally well tolerated.

Conclusion

Both low-dose methoxyflurane and N₂O are suitable options for the pain treatment of trauma patients in the emergency setting. Due to the ease of administration and portability, inhaled low-dose methoxyflurane, however, may not only offer advantages in emergency situations in remote or difficult-to-reach locations and mass-casualty situations but also be of significant value in urban and rural environments.

Psychomotor and cognitive effects of 15-minute inhalation of methoxyflurane in healthy volunteers: implication for post-colonoscopy care

Background and study aims: Colonoscopy with portal inhaled methoxyflurane (Penthrox) is highly feasible with low sedation risk and allows earlier discharge. It is unclear if subjects can return to highly skilled psychomotor skill task shortly after Penthrox assisted colonoscopy. We evaluated the psychomotor and cognitive effects of 15-minute inhalation of Penthrox in adults. Patients and methods: Sixty healthy volunteers (18 to 80 years) were studied on 2 occasions with either Penthrox or placebo in a randomized, double-blind fashion. On each occasion, the subject's psychomotor function was examined before, immediately, 30, 60, 120, 180 and 240 min after a 15-minute inhalation of studied drug, using validated psychomotor tests (Digit Symbol Substitution Test (DSST), auditory reaction time (ART), eye-hand coordination (EHC) test, trail making test (TMT) and logical reasoning test (LRT). Results: Compared to placebo, a 15-minute Penthrox inhalation led to an immediate but small impairment of DSST (P < 0.001), ART (P < 0.001), EHC (P < 0.01), TMT (P = 0.02) and LRT (P = 0.04). In all subjects, the performance of all 5 tests normalized by 30 minutes after inhalation, and was comparable to that with placebo. Although increasing age was associated with a small deterioration in psychomotor testing performance, the magnitude of Penthrox effects remained comparable among all age groups. Conclusions: In all age groups, a 15-minute Penthrox inhalation induces acute but short-lasting impairment of psychomotor and cognitive performance, which returns to normal within 30 minutes , indicating that subjects who have colonoscopy with Penthrox can return to highly skilled psychomotor skills tasks such as driving and daily work the same day.

Methoxyflurane Analgesia in Adult Patients in the Emergency Department: A Subgroup Analysis of a Randomized, Double-blind, Placebo-controlled Study (STOP!)

INTRODUCTION

Acute pain remains highly prevalent in the Emergency Department (ED) setting. This double-blind, randomized, placebo-controlled UK study investigated the efficacy and safety of low-dose methoxyflurane analgesia for the treatment of acute pain in the ED in the adult population of the STOP! trial.

METHODS

Patients presenting to the ED requiring analgesia for acute pain (pain score of 4-7 on the Numerical Rating Scale) due to minor trauma were randomized in a 1:1 ratio to receive methoxyflurane (up to 6 mL) or placebo (normal saline), both via a Penthrox® (Medical Developments International Limited, Scoresby, Australia) inhaler. Rescue medication (paracetamol/opioids) was available immediately upon request. Change from baseline in visual analog scale (VAS) pain intensity was the primary endpoint.

RESULTS

300 adult and adolescent patients were randomized; data are presented for the adult subgroup (N = 204). Mean baseline VAS pain score was ~66 mm in both groups. The mean change from baseline to 5, 10, 15 and 20 min was greater for methoxyflurane (-20.7, -27.4, -33.3 and -34.8 mm, respectively) than placebo (-8.0, -11.1, -12.3 and -15.2 mm, respectively). The primary analysis showed a highly significant treatment effect overall across all four time points (-17.4 mm; 95% confidence interval: -22.3 to -12.5 mm; p < 0.0001). Median time to first pain relief was 5 min with methoxyflurane [versus 20 min with placebo; (hazard ratio: 2.32; 95% CI: 1.63, 3.30; p < 0.0001)]; 79.4% of methoxyflurane-treated patients experienced pain relief within 1-10 inhalations. 22.8% of placebo-treated patients requested rescue medication within 20 min compared with 2.0% of methoxyflurane-treated patients (p = 0.0003). Methoxyflurane treatment was rated 'Excellent', 'Very Good' or 'Good' by 77.6% of patients, 74.5% of physicians and 72.5% of nurses. Treatment-related adverse events (mostly dizziness/headache) were reported by 42.2% of patients receiving methoxyflurane and 14.9% of patients receiving placebo; none caused withdrawal and the majority were mild and transient.

CONCLUSION

The results of this study support the evidence from previous trials that low-dose methoxyflurane administered via the Penthrox inhaler is a well-tolerated, efficacious and rapid-acting analgesic.

FUNDING

Medical Developments International (MDI) Limited and Mundipharma Research GmbH & Co.KG.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01420159, EudraCT number: 2011-000338-12.

Current concepts in management of pain in children in the emergency department

Pain is common in children presenting to emergency departments with episodic illnesses, acute injuries, and exacerbation of chronic disorders. We review recognition and assessment of pain in infants and children and discuss the manifestations of pain in children with chronic illness, recurrent pain syndromes, and cognitive impairment, including the difficulties of pain management in these patients. Non-pharmacological interventions, as adjuncts to pharmacological management for acute anxiety and pain, are described by age and development. We discuss the pharmacological management of acute pain and anxiety, reviewing invasive and non-invasive routes of administration, pharmacology, and adverse effects.

Efficacy of the methoxyflurane as bridging analgesia during epidural placement in laboring parturient

Background:

Establishing an epidural in an agitated laboring woman can be challenging. The ideal pain control technique in such a situation should be effective, fast acting, and short lived. We assessed the efficacy of inhalational methoxyflurane (Penthrox™) analgesia as bridging analgesia for epidural placement.

Materials and Methods:

Sixty-four laboring women who requested epidural analgesia with pain score of ≥7 enrolled in an observational study, 56 of which completed the study. The parturients were instructed to use the device prior to the onset of uterine contraction pain and to stop at the peak of uterine contraction, repeatedly until epidural has been successfully placed. After each (methoxyflurane inhalation-uterine contraction) cycle, pain, Richmond Agitation Sedation Scale (RASS), nausea and vomiting were evaluated. Maternal and fetal hemodynamics and parturient satisfaction were recorded.

Results:

The mean baseline pain score was 8.2 ± 1.5 which was reduced to 6.2 ± 2.0 after the first inhalation with a mean difference of 2.0 ± 1.1 (95% confidence interval 1.7-2.3, P < 0.0001), and continued to decrease significantly over the study period (P < 0.0001). The RASS scores continuously improved after each cycle (P < 0.0001). Only 1 parturient from the cohort became lightly sedated (RASS = −1). Two parturients vomited, and no significant changes in maternal hemodynamics or fetal heart rate changes were identified during treatment. 67% of the parturients reported very good or excellent satisfaction with treatment.

Conclusion:

Penthrox™ provides rapid, robust, and satisfactory therapy to control pain and restlessness during epidural placement in laboring parturient.

Portable inhaled methoxyflurane is feasible and safe for colonoscopy in subjects with morbid obesity and/or obstructive sleep apnea

BACKGROUND AND STUDY AIMS

Colonoscopy with inhaled methoxyflurane (Penthrox) is well tolerated in unselected subjects and is not associated with respiratory depression. The aim of this prospective study was to compare the feasibility, safety, and post-procedural outcomes of portable methoxyflurane used as an analgesic agent during colonoscopy with those of anesthesia-assisted deep sedation (AADS) in subjects with morbid obesity and/or obstructive sleep apnea (OSA).

PATIENTS AND METHODS

The outcomes of 140 patients with morbid obesity/OSA who underwent colonoscopy with either Penthrox inhalation (n = 85; 46 men, 39 women; mean age 57.2 ± 1.1 years) or AADS (n = 55; 27 men, 28 women; mean age, 54.9 ± 1.1 years) were prospectively assessed.

RESULTS

All Penthrox-assisted colonoscopies were successful, without any requirement for additional intravenous sedation. Compared with AADS, Penthrox was associated with a shorter total procedural time (24 ± 1 vs. 52 ± 1 minutes, P < 0.001), a lower incidence of hypotension (3 /85 vs. 23 /55, P < 0.001), and a lower incidence of respiratory desaturation (0 /85 vs. 14 /55, P < 0.001). The patients in the Penthrox group recovered more rapidly and were discharged much earlier than those in the AADS group (27 ± 2 vs. 97 ± 5 minutes, P < 0.0001). Of those who underwent colonoscopy with Penthrox, 90 % were willing to receive Penthrox again for colonoscopy. More importantly, of the patients who underwent colonoscopy with Penthrox and had had AADS for previous colonoscopy, 82 % (28 /34) preferred to receive Penthrox for future colonoscopies. Penthrox-assisted colonoscopy cost significantly less than colonoscopy with AADS ($ 332 vs. $ 725, P < 0.001), with a cost saving of approximately $ 400 for each additional complication avoided.

CONCLUSIONS

Compared with AADS, Penthrox is highly feasible and safe in patients with morbid obesity/OSA undergoing colonoscopy and is associated with fewer cardiorespiratory complications. Because of the advantages of this approach in regard to procedural time, recovery time, and cost benefit in comparison with AADS, further evaluation in a randomized trial is warranted.

Penthrox alone versus Penthrox plus periprostatic infiltration of local analgesia for analgesia in transrectal ultrasound-guided prostate biopsy

BACKGROUND

The objective of this study was to compare pain intensity in patients undergoing transrectal ultrasound (TRUS)-guided biopsy of the prostate with Penthrox alone compared with Penthrox plus periprostatic infiltration of local analgesia (PILA).

METHOD

Seventy-two subjects participated in this study after receiving appropriate education. Forty-two patients self-administered inhaled Penthrox (3 mL methoxyflurane) alone for analgesia (Group A), followed by 30 patients who self-administered Penthrox and received PILA with 5 mL of 2% lignocaine. All subjects had TRUS biopsy performed. Immediately after the procedure, patients were asked to rate their pain intensity using a numerical verbal rating scale from 0 to 10.

RESULTS

Baseline characteristics of the two groups were similar. Patients in Group B reported significantly lower post TRUS biopsy median pain intensity of 2 (1-3) compared with Group A subjects who reported a median post TRUS biopsy pain intensity of 3 (2-5) (P = 0.014). A total of 72 men underwent TRUS-guided biopsy. All patients indicated they would be happy to have another TRUS-guided prostate biopsy in the future.

CONCLUSION

Our study shows that Penthrox plus PILA shows promise as an efficacious and easily tolerated analgesic technique for outpatient TRUS biopsy, keeping resource use to a minimum. Planning for a multi-centre, double-blind randomized control trial comparing Penthrox plus PILA with PILA alone is presently underway.

Managing moderate and severe pain in mountain rescue

AIMS

We aimed to describe evidence-based options for prehospital analgesia, and to offer practical advice to physicians and nonphysicians working in mountain rescue.

METHODS

A literature search was performed; the results and recommendations were discussed among the authors. Four authors considered a scenario. The final article was discussed and approved by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) in October 2013.

RESULTS AND RECOMMENDATIONS

Many health care providers fail to recognize, assess, and treat pain adequately. Assessment scales and treatment protocols should be implemented in mountain rescue services to encourage better management of pain. Specific training in assessing and managing pain is essential for all mountain rescuers. Persons administrating analgesics should receive appropriate detailed training. There is no ideal analgesic that will accomplish all that is expected in every situation. A range of drugs and delivery methods will be needed. Thus, an 'analgesic module' reflecting its users and the environment should be developed. The number of drugs carried should be reduced to a minimum by careful selection and, where possible, utilizing drugs with multiple delivery options. A strong opioid is recommended as the core drug for managing moderate or severe pain; a multimodal approach may provide additional benefits.

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

Objective

To evaluate the short-term efficacy and safety of methoxyflurane for the treatment of acute pain in patients presenting to an emergency department (ED) with minor trauma.

Methods

STOP! was a randomised, double-blind, multicentre, placebo-controlled study conducted at six sites in the UK. A total of 300 patients, 90 of whom were adolescent patients (age 12–17 years), were randomised 150:150 to receive either methoxyflurane via a Penthrox inhaler or placebo. The primary end point of the study was the change in pain intensity as measured using the visual analogue scale (VAS) from baseline to 5, 10, 15 and 20 min after the start of study drug inhalation. Patients were supplied with one inhaler containing 3 mL methoxyflurane or 5 mL placebo after enrolment and initial assessments. Age group (adolescent/adult) and baseline VAS score were controlled for in the statistical analyses.

Results

A total of 149 patients received methoxyflurane, and 149 patients received placebo. Demographic and baseline characteristics were comparable between the groups. Methoxyflurane reduced pain severity significantly more than placebo (p<0.0001) at all time points tested, with the greatest estimated treatment effect of −18.5 mm (adjusted change from baseline) seen at 15 min after the start of treatment. Methoxyflurane was well tolerated, with the majority of adverse reactions being mild, transient and in line with anticipated pharmacological action.

Conclusion

The results of this study suggest that methoxyflurane administered via the Penthrox inhaler is an efficacious, safe, and rapidly acting analgesic.

Trial registration number:

NCT01420159.

Patient-controlled analgesia with inhaled methoxyflurane versus conventional endoscopist-provided sedation for colonoscopy: a randomized multicenter trial

OBJECTIVE

Inhaled methoxyflurane (Penthrox, Medical Device International, Melbourne, Australia) has been used extensively in Australasia (Australia and New Zealand) to manage trauma-related pain. The aim is to evaluate the efficacy, safety, and outcome of Penthrox for colonoscopy.

DESIGN

Prospective randomized study.

SETTING

Three tertiary endoscopic centers.

PATIENTS

Two hundred fifty-one patients were randomized to receive either Penthrox (n = 125, 70 men, 51.4 ± 1.1 years old) or intravenous midazolam and fentanyl (M&F; n = 126, 72 men, 54.9 ± 1.1 years old) during colonoscopy.

MAIN OUTCOME MEASUREMENT

Discomfort (visual analogue scale [VAS] pain score), anxiety (State-Trait Anxiety Inventory Form Y [STAI-Y] anxiety score), colonoscopy performance, adverse events, and recovery time.

RESULTS

Precolonoscopy VAS pain and STAI-Y scores were comparable between the 2 groups. There were no differences between groups in (1) pain VAS or STAI Y-1 anxiety scores during or immediately after colonoscopy, (2) procedural success rate (Penthrox: 121/125 vs M&F: 124/126), (3) hypotension during colonoscopy (7/125 vs 8/126), (4) tachycardia (5/125 vs 3/126), (5) cecal arrival time (8 ± 1 vs 8 ± 1 minutes), or (6) polyp detection rate (30/125 vs 43/126). Additional intravenous sedation was required in 10 patients (8%) who received Penthrox. Patients receiving Penthrox alone had no desaturation (oxygen saturation [SaO(2)] < 90%) events (0/115 vs 5/126; P = .03), awoke quicker (3 ± 0 vs 19 ± 1 minutes; P < .001) and were ready for discharge earlier (37 ± 1 vs 66 ± 2 minutes; P < .001) than those receiving intravenous M&F.

LIMITATIONS

Inhaled Penthrox is not yet available in the United States and Europe.

CONCLUSIONS

Patient-controlled analgesia with inhaled Penthrox is feasible and as effective as conventional sedation for colonoscopy with shorter recovery time, is not associated with respiratory depression, and does not influence the procedural success and polyp detection.

Inhaled methoxyflurane (Penthrox) sedation for third molar extraction: a comparison to nitrous oxide sedation

BACKGROUND

The aim of this study was to evaluate the use of inhaled methoxyflurane (Penthrox) in the reduction of dental anxiety in patients undergoing mandibular third molar removal in a specialist surgical suite and compare it to the conventional nitrous oxide sedation.

METHODS

A prospective randomized, non-blinded crossover design study of 20 patients receiving two types of sedation for their third molar extraction who participated in 40 treatment sessions. At first appointment, a patient was randomly assigned to receive either nitrous oxide sedation or intermittent Penthrox inhaler sedation, with the alternate regimen administered during the second appointment. Peri-procedural vital signs (heart rate and blood pressure) were recorded and any deviations from 20% from the baseline values, as well as any drop in oxygen saturation below 92% were documented. The Ramsay Sedation Scale (RSS) score was recorded every five minutes. Patient cooperation during the procedure, patients' general opinion about the sedation technique, surgeon satisfaction and the occurrence of side effects were all recorded. After the second procedure, the patient was also asked if he or she had any preference of one sedation technique over the other.

RESULTS

Levels of sedation were comparable in nitrous oxide and Penthrox sedation sessions. However, at 15 minutes of sedation it was significantly lighter (p < 0.05) in Penthrox. No patient in both regimens reached a RSS deeper than a score of 4. Parameters measured for assessment of sedation (patient cooperation, surgeon satisfaction and patient general opinion about sedation technique) were all similarly comparable for both nitrous oxide and Penthrox. In both sedation sessions, the odour of the inhalational agent was accepted by the patients; half of the patients (10 patients) who received methoxyflurane thought its odour was pleasant. Patients preferred methoxyflurane (Penthrox) inhalation over nitrous oxide sedation (Fisher's Exact test, p < 0.05). Adverse events were minimal. No patient was either deeply sedated or agitated. Blood pressure was within ± 20% from the baseline values. No patient had oxygen saturation less than 92%. Dizziness was the most frequently encountered side effect in both regimens (four patients each). Two patients had bradycardia (HR < 60 beats/minute) when nitrous oxide was used in comparison to one patient with Penthrox sedation. Paraesthesia of fingers and heaviness of the chest was encountered only with nitrous oxide sedation (four patients). Mild self-limited shivering occurred in one patient with Penthrox sedation.

CONCLUSIONS

The Penthrox Inhaler can produce a comparable sedation to that of nitrous oxide for the surgical extraction of third molars under local anaesthesia.