A pilot study of inhaled methoxyflurane for procedural analgesia in children.
BACKGROUND
Methoxyflurane (MF), a potent volatile anesthetic, can be used as an analgesic in subanesthetic concentrations. In Australia, MF is extensively used in children and adults as an analgesic in the prehospital setting via a hand-held inhaler device. We conducted a pilot study to explore its use as a patient controlled analgesic for painful procedures in children in the emergency department (ED).


METHODS
This is a prospective observational case series of children aged 5 years and older requiring procedural analgesia for brief painful procedures. Pain scores, depth of sedation, adverse events and patient, parent and staff satisfaction were assessed as well as consumption of MF measured.


RESULTS
Fourteen patients (aged 6-13 years) received MF mainly for extremity injuries. Amount of MF consumed ranged from 0.36 to 3.06 g per patient inhaled over 4-25 min. There were no serious adverse events. No patient was deeply sedated. Five patients had mild brief self-resolving adverse events including agitation, euphoria, blurry vision, dizziness and cough. Four patients with fractures with initial high pain scores (> or =6) received MF for bridging analgesia with large drops in pain scores. Four patients who required fracture reductions with initial low scores did not achieve adequate analgesia. The remaining six patients had painful procedures undertaken with satisfactory analgesia.


CONCLUSIONS
On the basis of this small pilot study of MF use in children in the ED, this agent appears to be a powerful analgesic. MF seems most useful as a self-titrated bridging analgesic agent in patients after extremity trauma. It appears less useful as a procedural agent when patients are unable to anticipate and achieve a sufficient level of analgesia before painful stimulus infliction. Pre- and intraprocedure coaching is an important aspect of its use especially if initial pain scores are low.
Babl
Franz
F
Department of Emergency Medicine, Royal Children's Hospital and Murdoch Childrens Research Institute, Melbourne, Australia. franz.babl@rch.org.au
Barnett
Peter
P
Palmer
Greta
G
Oakley
Ed
E
Davidson
Andrew
A
D000293:Adolescent; D016058:Analgesia, Patient-Controlled / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D000769:Anesthesia, Inhalation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D018685:Anesthetics, Inhalation / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D001315:Australia; D002648:Child; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008733:Methoxyflurane / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy; D010147:Pain Measurement / Q000379:methods / Q000706:statistics & numerical data; D017060:Patient Satisfaction / Q000706:statistics & numerical data; D010865:Pilot Projects; D011446:Prospective Studies; D013997:Time Factors
D018685:Anesthetics, Inhalation; D008733:Methoxyflurane