Overview
The aim of this study is to determine if 3ml of inhaled Methoxyflurane, in the form of a Penthrox inhaler, reduces pain during IUD insertion and/or endometrial biopsy. The proposed study is a double-blind, placebo-controlled RCT.
Each participant will be randomly assigned to one of two arms:
- Intervention (3ml of Methoxyflurane via a Penthrox inhaler)
- Placebo (3ml of normal saline via an identical placebo Penthrox inhaler)
The primary outcome is global pain score, which will be patient-reported by the 100 mm Visual Analogue Scale (VAS) 5-minutes following the procedure (endometrial biopsy or IUD insertion).
Eligibility
Inclusion Criteria
- Any participant ≥18 years and ≤ 65 years presenting for an IUD insertion or endometrial biopsy
- For IUD insertion, only nulliparous patients
- English speaking participants only
- Availability of a ride home from the appointment
Exclusion Criteria
- Use of pain medication that is not an NSAID or acetaminophen (e.g. opioids, benzodiazepines) within past 24 hours
- Misoprostol administration within 24 hours
- Breastfeeding
- Any diagnosed chronic pain syndromes (e.g. fibromyalgia, vaginismus)
- Allergy to methoxyflurane
- Renal or liver disease
- Known or genetically susceptible to malignant hyperthermia or a history of severe adverse reactions in either patient or relatives
- Baseline vital signs of systolic blood pressure <100, diastolic blood pressure <60 and/or pulse <60.
- Previous unsuccessful office attempt of IUD insertion or endometrial biopsy by the same practitioner (note of clarification: previous unsuccessful IUD insertion or biopsy attempt by a different practitioner will still be eligible)
- Clinically evident respiratory impairment