Clinical trial to compare pain relief between methoxyflurane and any analgesic treatment used in usual clinical practice, in patients with trauma and associated pain, treated in Spanish emergency units.

Open, randomized clinical trial to compare emergency pain relief between methoxyflurane and standard of care in patients with trauma and associated pain, treated in Spanish emergency units.

Methoxyflurane is a fluorinated ethyl methyl ether, with the chemical name 2:2-dichloro-1:1-difluoroethyl methyl ether. It belongs to the fluorinated hydrocarbon group of volatile anaesthetics. It is inhaled as a vapour at low (sub-anaesthetic) concentrations to achieve an analgesic effect for the management of pain.

In Europe countries, where methoxyflurane is already marketed, it is indicated for emergency relief of moderate to severe pain in conscious adult patients with trauma and associated pain.

On the other hand, current clinical practice includes a variety of analgesic agents, with the choice of which to employ based on consideration of the risk-benefit factors of each class of drug, as well as the type of pain, its severity, and the risk of adverse effects.

The main objective of this study is to assess Methoxyflurane's significant advantage in terms of anaglesic effectiveness, as it is known as a rapidly acting, non-narcotic analgesic for the treatment of emergency pain.

Inclusion Criteria:

• Adult patients: ≥ 18 years of age
• Moderate to severe pain (NRS 0-10; >=4) secondary to trauma
• Without anticipating surgery due to the trauma, requiring hospitalization (hospital stay 12h)
• Conscious patient.
• Giving informed consent in writing

Exclusion Criteria:

• Hypersensitivity to methoxyflurane (MEOF) or any fluorinated anaesthetic.
• Malignant hyperthermia: patients with known or genetically susceptible to malignant hyperthermia or a history of severe adverse reactions in either patient or relatives.
• Patients who have a history of showing signs of liver damage after previous MEOF use or halogenated hydrocarbon anaesthesia
• Known clinically significant renal impairment
• Known pregnant or likely to be pregnant women at the time of inclusion.
• Clinically evident cardiovascular instability
• Clinically evident respiratory depression
• Patients taken any analgesic for the traumatic pain before inclusion
• Altered level of consciousness due to any cause, including head injury, drugs or alcohol
• Degenerative diseases, mental illness or other conditions that could affect ability of valuing pain intensity
• Patients to be unable to understand the purpose of the study and perform self-assessments, following investigator's criteria.
• Participation in another clinical trial within 30 days prior to randomization