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Three Part Question

In [adult patients requiring reduction of anterior shoulder dislocation] is [treatment with inhaled methoxyflurane] associated with [an acceptable reduction rate and decreased time spent in the ED?]

Clinical Scenario

A 44-year-old patient presents to the emergency department (ED) with a deformed and painful right shoulder after a hard tackle playing rugby. An X-ray confirms right anterior glenohumeral dislocation with no associated fracture. You would like to attempt a closed reduction. Unfortunately, your department is too busy for a full procedural sedation. You wonder what your likelihood of success would be using only inhaled methoxyflurane (Penthrox®) and whether this would facilitate a quicker discharge from ED.

Search Strategy

1. ((methoxyflurane and dislocat*) or (methoxyflurane and shoulder*)).ab,ti.
2. ((Penthrox and dislocat*) or (Penthrox and shoulder*)).ab,ti.
3. ((methoxyflurane and shoulder) or (methoxyflurane and shoulder dislocation) or (methoxyflurane and dislocation)).de.
4. 1 or 2 or 3
EMBASE, MEDLINE, and Cochrane databases were searched utilising the Ovid interface and the above strategy utilising keywords and Medical Subject Headings (MeSH).

No search filters were used, including language and date of publication.

The Google Scholar ‘cited by’ function was then used to find studies that had referenced the papers we identified as relevant in our database searches.

Finally, the reference lists of relevant papers were screened for studies missed by our search process.

Search Outcome

Thirty papers were identified using our search strategy after removal of duplicate records. Eighteen were excluded on abstract review as they were not relevant to the three-part question outlined above. Twelve texts underwent full text review. Four were excluded as they were non-peer-reviewed conference posters. One was excluded as it was a pre-hospital study.

Seven papers [1-7] were retained for final analysis: six observational studies and one single-arm trial. One study [4] was excluded as the authors reported combined findings for shoulder and elbow dislocation and did not respond to our requests for separate data. Three authors were contacted [1,3,7] to provide additional data and two [1,7] did so.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ameh et al. 2022 UK	Adults (n = 10) presenting to ED with ASD Male: 50% Average age: 57.6 Recurrent ASD: 0%	Single-centre retrospective observational study Level 3b	Successful reduction rate	100%	Small sample. Reduction technique(s) and seniority of clinicians not specified. Reliant upon potentially incomplete charting data. Unclear if other pre-procedure analgesia administered.
Campbell et al. 2022 Canada	Adult patients (n = 20) presenting to ED with ASD Male: 80% Average age: 38.6 Recurrent ASD: 40%	Single-centre single-arm trial Level 2b	Successful reduction rate	35%	Small sample. Practitioners restricted to Cunningham reduction technique. Non-randomised trial design. Did not control for pre-hospital analgesia. Study funded by manufacturers of Penthrox ®
			Average length of A&E stay	149 minutes
			Patient satisfaction with procedure	Excellent: 35% Very good: 35% Good: 10% Fair: 15% Poor: 5%
Gray Stephens et al. 2023 UK	Adult patients (n = 16) presenting to ED with ASD Male: N/S Average age2: N/S Recurrent ASD: N/S	Single-centre retrospective observational study Level 3b	Successful reduction rate	62.5%	Small sample with no demographic data provided. Reduction technique(s) not specified. Mixed seniority of practitioners and relationship between outcomes and training level not formally analysed. Reliant upon potentially incomplete charting data.
			Admission rate	0%
Troppmann & Cavenaile 2022 France	Adult patients (n = 57) presenting to ED with ASD Male: 80% Average age: 37 Recurrent ASD: 46%	Single-centre retrospective observational study Level 3b	Successful reduction rate	47%	Reduction technique(s) and seniority of clinicians not specified. Reliant upon potentially incomplete charting data.
			Average length of A&E stay	123 minutes
			Average time to reduction	68 minutes
Umana et al. 2019 Ireland	Adult patients (n = 30) presenting to ED with ASD Male: 60% Average age2: 32 Recurrent ASD: N/S	Single-centre retrospective observational study Level 3b	Successful reduction rate	80%	Small sample with no demographic data provided. Mixed pre-procedure analgesia provided. Reduction technique(s) and seniority of clinicians not specified. Reliant upon potentially incomplete charting data.
			Average length of A&E stay	70.5 minutes
			Adverse events	0
			Average recovery time	30 minutes
Young et al. 2020 UK	Adult patients (n = 13) presenting to ED with ASD Male: 69.2% Average age: 45.6 Recurrent ASD: N/S	Single-centre prospective cohort study Level 2b	Successful reduction rate	61.5%	Sample size not specified and no demographic data provided. Reduction technique(s) and seniority of clinicians not specified. Unclear if consecutive sampling used. Partially reliant on potentially incomplete charting data.
			Length of A&E stay	167 minutes
			Adverse events	0

Comment(s)

Our key results are summarised in Table 1. Studies demonstrated a variable success rate using methoxyflurane for anterior shoulder dislocation: between 35% and 100% in samples comprising both recurrent [3,6,7] and first-time [1,2,5] dislocators. Three studies utilised a comparator group: methoxyflurane significantly reduced ED length of stay by 64.5 minutes [p<0.001] compared to propofol [6], 60 minutes [p=0.03] compared to morphine and midazolam [5], and 183 minutes [p=0.009] compared to an unspecified ‘standard care group’ [7]. The findings of this review should be interpreted with caution as there may have been significant selection bias involved in clinicians’ choice of patients “suitable” for methoxyflurane. The lowest success rates were found in the only study that used consecutive sampling [2], although in this single-arm trial the clinicians were limited to one reduction technique. One study [2] explored patient experience. The authors found that patients generally reported good satisfaction with methoxyflurane even if reduction was not achieved. This may be attributed to the persistent analgesic effect of methoxyflurane, which can persist for several hours post-procedure. A randomised controlled trial is clearly needed to fully answer this question. In the meantime, it seems reasonable based on the available evidence to attempt reduction with methoxyflurane – particularly in congested departments where patients are likely to be waiting a long time, in pain, for a full procedural sedation.

Clinical Bottom Line

Methoxyflurane has been associated with favourable success rates as a sole facilitating agent for anterior shoulder reduction in first-time and recurrent dislocators. It may improve patient flow through the ED.

References

1. Ameh V, Abbasi A, Basir H. Shoulder Dislocation in the Emergency Department: Experience within a Large District General Hospital. Annals of PIMS 2022
2. Campbell S, Wiemer H, Fitzpatrick R, Carriere C, Teed S, Hico P, Snook A A Pilot Study of Inhaled Low-dose Methoxyflurane to Support Cunningham Reduction of Anterior Shoulder Dislocation Eurasian Journal of Emergency Medicine 2022
3. Gray Stephens CE, Dias A, Skinner E, Brennan C, Middleton RG, Angel CK Penthrox enables quicker management of fractures, dislocations and more: learning lessons from expedited care of trauma patients during the COVID-19 pandemic The Annals of The Royal College of Surgeons of England 2023
4. Troppmann L, Cavenaile J Apport du méthoxyflurane inhalé dans la prise en charge des luxations d’épaule aux urgences Rev Med Brux 2022
5. Umana E, Kelliher JH, Blom CJ, McNicholl B Inhaled methoxyflurane for the reduction of acute anterior shoulder dislocation in the emergency department Canadian Journal of Emergency Medicine 2019
6. Young L, Bailey GP, McKinlay JA Service evaluation of methoxyflurane versus standard care for overall management of patients with pain due to injury Advances in Therapy 2020