Reduction of Anterior Shoulder Dislocation Facilitated by Inhaled Low Dose Methoxyflurane
Reduction of Anterior Shoulder Dislocation Facilitated by Inhaled Low Dose Methoxyflurane
This pilot study will test the feasibility of doing a definitive study to ascertain whether
 reduction of shoulder dislocation can be safely and effectively facilitated by a patient
 controlled inhalational analgesic, negating the need for potentially dangerous PSA and the
 use of intravenous therapy. The hypothesis includes that time to reduction and time spent in
 the emergency department will be reduced.
Anterior shoulder dislocation, in which the head of the humerus (cup) comes out of its
 position in the glenoid fossa (saucer), to lie anterior and below its proper position, is a
 common emergency department presentation. Between April 1, 2011 and March 31, 2018, 1654
 patients presented to emergency departments in Emergency Departments of the Central Zone of
 the Nova Scotia Health Authority (Average 236/year). The treatment of dislocated shoulder
 involves reduction to a normal anatomical position as soon as possible, to manage pain and
 disability and to minimize the chance of poor long term outcome. Numerous methods exist to
 effect reduction, most of which are conducted under procedural sedation and analgesia (PSA)
 that allows the shoulder muscles to relax so that they do not hold the humeral head in a
 dislocated position. PSA involves the administration of intravenous sedatives and narcotic
 analgesics. Not only do the medications carry the risk of respiratory depression and
 hypotension, but their duration of action results in longer emergency department stays and
 the use of intravenous lines, is invasive and adds patient discomfort and expense to the
 procedure. An additional risk of PSA in this specific population is that reduction of the
 dislocation to its normal position, immediately removes the painful stimulus that antagonizes
 the respiratory depression of the sedative and analgesic agents. This often results in
 unopposed respiratory depression which might be unrecognized as the 'crisis' appears to be
 over with the restoration of the shoulder joint. Furthermore, PSA requires specifically
 trained staff and space; and time taken to arrange PSA prolongs the time during which the
 humerus is out of position. It has been reported that from the time of arrival in the
 emergency department with an anterior shoulder dislocation, every 10 min delay in reduction
 attempt increased the odds of a failed reduction attempt by 19%. In the Charles V. Keating
 Emergency and Trauma Centre in Halifax, Nova Scotia, PSA is conducted by specially trained
 advanced care paramedics using standard preparation, monitoring and recovery protocols. In an
 effort to painlessly reduce shoulder dislocations without PSA, the Cunningham technique has
 been described, which involves massaging the shoulder muscles in an attempt to get them to
 relax sufficiently to allow reduction. Although this method does work, and has been
 associated with decreased need for PSA, it is associated with an increase in the rate of
 unsuccessful first reduction attempts. After unsuccessful attempts using the Cunningham
 technique, the fallback is generally to then provide PSA, increasing the time to reduction.
 Inhaled low-dose methoxyflurane has been used for several decades in Australia as an
 emergency analgesic for short-term use. Administered via a portable, disposable, single-use
 hand-held inhaler device administered by the patient for pain relief, it offers a safe and
 effective non-opioid alternative to morphine. Inhaled methoxyflurane has been shown to be
 safe, effective, and simple to administer in obstetric patients during childbirth, as well as
 for patients with bone fractures and joint dislocations, and for dressing changes on burn
 patients. In 2018, PenthroxTM (methoxyflurane) received marketing authorization from Health
 Canada for adult patients requiring short-term relief from moderate to severe acute pain
 associated with trauma or interventional medical procedures. Low dose methoxyflurane adds to
 the armamentarium of Canadian emergency care providers as an option that is relatively
 inexpensive, safe and very easy to administer rapidly. As most failures of the Cunningham
 anterior shoulder reduction method are due to patient discomfort, the investigators
 hypothesize that inhaled low dose methoxyflurane has the potential to increase first attempt
 success rates using this method while decreasing the time from arrival to reduction, the need
 for intravenous therapy or the use of potentially dangerous medications. The Penthrox
 inhalers will be supplied by Purdue and will be stored in the emergency department in a
 locked cabinet in a locked box with limited access. It is a self controlled inhaled
 medication controlled by each inhalation. Each breath a patient takes releases a fraction of
 the single dose contained in the inhaler.
Inclusion Criteria:

 -  Anterior dislocation not complicated by fracture (pre-reduction x-rays will be done at
 the discretion of the emergency physician)

 -  No neurological or vascular injury

 -  Patients greater than or equal to 18 years of age

 -  Patients able to understand the nature of the study and give written informed consent

 -  Patient is able to follow all study requirements and procedures and complete all
 questionnaires

 Exclusion Criteria:

 -  Previous shoulder surgery on the affected side

 -  Associated fracture or secondary significant injury

 -  Previous in-hospital reduction attempt for the current dislocation

 -  Open wound or infection in the vicinity of the joint

 -  Uncorrectable altered level of consciousness, to be defined by the attending clinician
 as a Glasgow-Coma Scale of less than 15, due to any cause, including head injury,
 drugs, or alcohol

 -  History of clinically significant renal impairment

 -  History of liver dysfunction after previous methoxyflurane use or other halogenated
 anesthetics

 -  Hypersensitivity to methoxyflurane or other halogenated anesthetics

 -  Known or genetically susceptible to malignant hyperthermia or a history of severe
 adverse reactions in either patient or relatives

 -  Clinically evident hemodynamic instability

 -  Clinically evident respiratory impairment

 -  Has received methoxyflurane within the past 3 months