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Three Part Question

In [adult patients with anterior shoulder dislocation] is [methoxyflurane a valid alternative to procedural sedation and analgesia] at [decreasing pain, Emergency Department length of stay (ED LOS) and facilitating successful reduction]

Clinical Scenario

A young man attends the emergency department having sustained an acute anterior shoulder dislocation in a rugby tackle. Peripheral venous access has not yet been obtained. You wonder if inhaled methoxyflurane (MF) could be as effective as procedural sedation and analgesia (PSA) in facilitating successful shoulder reduction whilst reducing length of departmental stay.

Search Strategy

Medline 1966-07/2022 using the OVID interface and Embase using the Embase database.
[methoxyflurane OR penthrox] AND [shoulder dislocation OR anterior shoulder dislocation OR glenohumeral dislocation]. LIMIT to human adults (>=16 years) and English language. The search strategy was last applied on 11 October 2022

Search Outcome

Two papers were identified in Medline and a further 11 papers were identified in Embase, of which 3 were irrelevant or of insufficient quality. Following a review of the references of relevant papers a further 10 papers were found. A total of 3 papers were deemed relevant following full text review and are included in the table below.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ho et al 2021 Singapore	192 adult patients with acute shoulder or acute elbow dislocation (74 received MF, 118 received PSA) 153 acute shoulder dislocation: 68 MF, 85 PSA	Retrospective cohort study (2b)	Patients' ED LOS	Median ED LOS was significantly reduced in those that received MF compared with PSA (99.0 vs 246.5 mins, p<0.001)	Imbalance in MF vs PSA group size. Heterogeneity in procedural sedation and analgesia agents used. Patients with prior dislocation were more prevalent in the MF group (33.8% vs 18.6%). Incomplete pain score data (not included in analysis). 39 cases (6 MF, 33 PSA) were acute elbow dislocations (20.3%) which were not analysed separately to shoulder dislocations. Potential selection bias as use of MF or PSA was at the discretion of the treating physician. This also introduces the possibility of confounding by indication. It is unclear which reduction techniques were employed. This may affect the chance of success and duration of procedure. It is unclear whether other analgesic agents or adjuncts such as ice, NSAIDs or paracetamol were used.
			Duration of procedure	Median duration of procedure was significantly shorter in the MF group (16.0 vs 32.0 mins, p<0.001)
			First attempt successful reduction	Successful reduction on first attempt showed no statistically significant difference between MF and PSA (86.5% vs 90.7%, P=0.365)
Umana et al 2019 Ireland	82 patients with acute shoulder dislocation (30 received MF, 52 received propofol)	Retrospective cohort study (2b)	Patients' ED LOS	Median ED LOS was significantly reduced in those that received MF compared with propofol who had successful reductions (70.5 vs 135 mins, P<0.001)	Imbalance in MF vs PSA group size. Potential selection bias as use of MF or propofol was at the discretion of the treating physician. This also introduces the possibility of confounding by indication. No pain score data. Reduction technique was at the discretion of the treating physician and may affect the chance of successful reduction. Some patients were administered additional analgesia at triage, which may affect chance of reduction and recovery time.
			Duration of procedure	Median recovery time shorter for MF who had successful reductions (30 vs 47 mins, P<0.004)
			First attempt successful reduction	Successful reduction was achieved in 80% of patients who received MF versus 98% in propofol group (p value not reported)
Young et al 2020 England	159 adult patients with moderate to severe trauma pain and GCS of 15 79 MF, 80 standard care	Prospective cohort study (2b)	Patients’ ED LOS	Mean ED LOS significantly reduced in those that received MF compared with standard care for patients with acute shoulder dislocation (167 vs 350 min, P=0.009)	Although subgroup analysis was performed for ED LOS, the number of patients in shoulder dislocation group is not stated Incomplete pain score data (not included in analysis) Heterogeneity in PSA agents used (standard care was intravenous opioids or procedural sedation in majority of cases but other against included local anaesthetic regional block, oral opioids and paracetamol) It is unclear which reduction techniques were employed. This may affect the chance of success and duration of procedure.

Comment(s)

There is a paucity of evidence to determine whether inhaled MF is a valid alternative to PSA in the reduction of acute anterior shoulder dislocation. The assembled evidence suggests a significant reduction in ED LOS and a reasonable chance of successful reduction with MF alone. This could contribute to a significant reduction in cost to healthcare services. Prospective research that can produce a higher quality of evidence, including randomised controlled trials, is required to validate the observed reduction in ED LOS associated with use of MF. Further studies should also investigate MF versus single agents to reduce the heterogeneity in the PSA group. Reduction in pain scores of the two methods should also be considered.

Clinical Bottom Line

MF can facilitate successful reduction and reduce length of stay when used as a first-line agent for acute anterior shoulder dislocation in adults, prior to considering PSA. The relative impact on pain scores and overall cost benefit of MF versus PSA is yet to be evidenced.

References

1. Shu Fang Ho, Sameera Ganti, Eunizar Omar, Sherman Wei Qiang Lian, Hui Cheng Tan, Yogeswary Pasupathy, Norizan Jaafar, Faraz Zarisfi and Marcus Eng Hock Ong Comparison of inhaled methoxyflurane versus procedural sedation for manipulation and reduction of acute shoulder and elbow dislocation in the emergency department Proceedings of Singapore Healthcare February 2021
2. Etimbuk Umana, Josephine Hannah Kelliher, Christiaan Johannes Blom, Brian McNicholl Inhaled methoxyflurane for the reduction of acute anterior shoulder dislocation in the emergency department Canadian Journal of Emergency Medicine July 2019, 468-472
3. Louise Young, George P. Bailey, Jayne A. C. McKinlay Service Evaluation of Methoxyflurane Versus Standard Care for Overall Management of Patients with Pain Due to Injury Advances in Therapy March 2020; 2520-2527