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Completed

NCT Number: NCT04618497

A Pilot Study on the Use of Methoxyflurane (Penthrox®) for Pain Control in the Emergency Department

Patients commonly visit the emergency department (ED) for pain after musculoskeletal injury and need early treatment with analgesic. Prompt and adequate pain relief can reduce suffering and promote early discharge and return to work. Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are the major injectable analgesic used for moderate to severe pain in EDs in Hong Kong. They are given via intravenous or intramuscular route for faster onset of action to achieve rapid pain relief in the emergency setting. However, injections are invasive and can be distressing for patients. Methoxyflurane (Penthrox®) is recently introduced to our emergency department as an inhalational analgesic. It has been granted registration approval in Hong Kong since 2018, but it is not widely used in the locality. Methoxyflurane is a volatile fluorinated hydrocarbon self-administrated by inhalation through a portable hand-held whistle-shaped inhaler device (Penthrox®) to relieve pain associated with trauma or minor surgical procedures in stable and conscious patients. In this study, the investigators will evaluate the efficacy and safety Penthrox® in the treatment of acute traumatic pain in hospital emergency department setting by comparing it to another conventional analgesic commonly used.

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Key information

Conditions

Acute Traumatic Pain

Age range

18 year–64 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Hospital Authority

Hong Kong

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients of both sexes from 18 to 64 years of age
  • Presented to the ED in Ruttonjee Hospital for musculoskeletal injury within 72 hours of onset (Types of injury include contusion, sprain, crushing, burn, laceration, fracture and dislocation)
  • Moderate pain at screening (10-point Numeric Rating Scale ≥4 to ≤7)

Exclusion criteria

  • Critical or life-threatening condition requiring resuscitation
  • Limb-threatening condition or any injuries requiring immediate management
  • Hemodynamically unstable (systolic blood pressure <90 mmHg, diastolic blood pressure <60mmHg)
  • Respiratory distress with respiratory rate >20 breath per minute or oxygen saturation <95% on room air
  • Pregnant or breastfeeding women
  • Impaired consciousness from any cause such as head injury and acute intoxication, based on the judgement of investigator
  • Any physical, visual or cognitive conditions that may affect patient's ability to use visual analog scale for self-assessments of pain intensity
  • Concomitant use of other analgesic within 5 hours (8 hours for diclofenac sodium) prior to presentation to ED
  • Other pre-existing chronic pain condition
  • Unable or refuse to provide written informed consent
  • Unable to understand and converse in the language spoken
  • Contraindication to inhalational methoxyflurane
  • Known personal or family history of hypersensitivity to methoxyflurane or any fluorinated anesthetics
  • Known pre-existing clinically significant renal or hepatic impairment
  • Known personal or family history of malignant hyperthermia
  • Concomitant use of nephrotoxic agents such as gentamicin, tetracycline, colistin, polymyxin B and amphotericin B
  • Concomitant use of cytochrome P450 inducers such as alcohol, isoniazid, phenobarbital and rifampicin
  • Contraindication to intramuscular ketorolac
  • Known allergy to NSAIDS
  • Known pre-existing clinically significant renal impairment or at risk for renal failure due to volume depletion
  • Active major bleeding
  • Suspected or confirmed cerebrovascular bleeding
  • History of peptic ulcer disease, gastrointestinal bleeding or perforation
  • Concomitant use of aspirin, other NSAIDS, anticoagulant or novel anticoagulant agent, pentoxifylline and probenecid
  • Known bleeding disorders such as haemophilia, thrombocytopenia
  • Heart failure
  • Per-operative period of coronary artery bypass graft (CABG) surgery
  • Concurrent asthmatic attack

Treatment and study plan

Methoxyflurane

Drug

Each patient in the methoxyflurane group will use one Penthrox inhaler under supervision of trained personnel. After priming the inhaler with 3 mL of methoxyflurane, patient is instructed to inhale through the mouthpiece to obtain analgesia, and then exhale back into the mouthpiece so that any unmetabolized methoxyflurane can be adsorbed by activated charcoal chamber. First few breaths should be gentle and then breathe normally through Inhaler. Onset of pain relief is rapid and occurs after 6-10 inhalations. If stronger analgesia is required, patient can cover the diluter hole with a finger during inhalation. Patients are able to titrate the amount of methoxyflurane inhaled and should be instructed to inhale intermittently to achieve adequate pain control.

Other names: Penthrox

Ketorolac

Drug

Each patient in the ketorolac group will receive one dose of 30mg intramuscular ketorolac injected at gluteal muscle by nursing staff as usual daily practice.

Other names: Toradol

Primary outcomes

  1. The change in pain intensity over 60 mins in terms of 100-mm VAS

    Time frame: Measure at baseline and at 5, 15, 30 and 60 minutes after drug administration

    Patients are instructed to complete a questionnaire with visual analogue scale (VAS), a 100-mm horizontal straight line whereas"0" at the left end indicates "no pain at all" and "10" at the right end indicates "the worst possible pain I can imagine".

Secondary outcomes

  1. Blood pressure

    Time frame: Measure at baseline and at 5, 15, 30 and 60 minutes after drug administration

    Blood pressure in mmHg

  2. Pulse Rate

    Time frame: Measure at baseline and at 5, 15, 30 and 60 minutes after drug administration

    Pulse Rate in beat per minute

  3. Oxygen saturation

    Time frame: Measure at baseline and at 5, 15, 30 and 60 minutes after drug administration

    Oxygen saturation in %

  4. Level of sedation

    Time frame: Measure at baseline and at 5, 15, 30 and 60 minutes after drug administration

    Ramsay Sedation Scale 1-6. 1 indicates patient is anxious and agitated or restless, or both; 2 indicates patient is co-operative, oriented, and tranquil; 3 indicates patient responds to commands only; 4 indicates patient exhibits brisk response to light glabellar tap or loud auditory stimulus; 5 indicates patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus; 6 indicates patient exhibits no response.

  5. Drug-related adverse events

    Time frame: After drug administration until the end of the observation period (1 hour)

    Patients are advised to report any discomfort any time during the study period. The investigator would judge whether the complaint is drug-related and give corresponding treatment. If the patients have no active complaint, they would be asked on a checklist for possible related adverse events before discharge. The nature and severity of adverse events would be documented. To exclude any late effects, discharged patients are encouraged to return to the department if they experience any adverse events.

  6. Use of rescue medication

    Time frame: After drug administration until the end of the observation period (1 hour)

    Analgesics given after study drug administration in either group are considered as rescue medication. It will be given any if the patient requests or pain improvement is insufficient based on judgement of the attending physician. The name of rescue medication, dosage, time and route of administration will be documented.

  7. Level of patient's satisfaction

    Time frame: After drug administration until the end of the observation period (1 hour)

    Patients are instructed to rate the overall efficacy and acceptance of the drug by five-point Likert scale on a questionnaire.

Sponsors and collaborators

Lead sponsor

Hospital Authority, Hong Kong

Other Gov

Registry information

Important dates

Study start
2020
Primary completion
2020
Study completion
2020
First posted
Nov 6, 2020
Registry last updated
Dec 8, 2020

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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