Efficacy of Inhaled Methoxyflurane (Penthrox) as Adjunct for Urologic Procedures Under Local Anesthetic: A Pilot Study

This non-blinded, randomized controlled trial is to be conducted at both the Men's Health Clinic and Health Sciences Centre in Winnipeg, Manitoba. All eligible patients between the ages of 18-65, undergoing andrology and male infertility under local anesthetic or select endourology procedures under loco-sedation, will be invited to participate in the study. Patients will be excluded if; history of substance use disorder, history renal impairment, history of liver dysfunction, previous hypersensitivity to Penthrox or related agents, personal or family history of malignant hypothermia. They will be randomly assigned in a 1:1 ratio using a computer-generated random list. For penoscrotal cases, patient will be randomized to Penthrox + local infiltration of 50/50 lidocaine and bupivacaine mixture vs local infiltration alone. For select endourology procedures, patients will be randomized to Penthrox + topical local anesthetic vs IV sedation + topical anesthetic. Participants may begin using the Penthrox 10 minutes prior to procedure start given its median time of onset of 5 minutes. In the post-operative recovery area, patient will be asked to complete a questionnaire related to pain and anxiety of procedure.

Baseline characteristics such as age, use of analgesics, prior history of procedure under loco-sedation, history of chronic pain, baseline pain level (Brief Pain Inventory), pre-procedural anxiety (State Trait Anxiety Inventory) will be collected.

Inclusion criteria

• Adult patients undergoing hydrocelectomy, spermatocelectomy, epididymectomy, testicular biopsy, scrotal lesion or cyst excision under local anesthesia alone will be included.

Exclusion criteria

• Patients will be excluded if their procedure was to be performed with sedatives (e.g., inhaled nitrous oxide gas, oral, or IV sedation) or did not provide consent to be randomized