Document resource
Introduction The principle means of providing analgesia during colonoscopy in the UK is either through conscious sedation, or use of entonox, a fast-acting inhaled and self-administered analgesic gas. Entonox allows the patient to go home without an escort, but its effectiveness is limited and there are considerable concerns over its environmental impact. Penthrox (99%) methoxyflurane) is an alternative inhaled analgesic with a climate impact 117 lower in CO2e already in use in other procedures such as hysteroscopy. Moreover, trial data exists establishing non-inferiority to conscious sedation during colonoscopy. We wished to establish a pilot study in the UK to assess if penthrox is a suitable analgesic in colonoscopy.Methods Suitable patients were screened at pre-assessment and offered penthrox as an alternative to entonox.Patients who received penthrox completed a post procedure survey of 9 questions derived from the Endoprem questionnaire (questions E14- G1). Procedural data was retrospectively collected from endoscopy reports to evaluate outcomes, and all 3 endoscopists who performed procedures with penthrox gave feedback on their overall experience at the end of the trial period.Results To date, 22 patients (6 female; mean age 57.3 years (SD 11.6 years)) have undergone a procedure with penthrox (20 colonoscopies, 2 flexible sigmoidoscopies). One colonoscopy was abandoned due to intolerance; all others met clinical intention without rescue IV sedation, and with no adverse events. Ileal intubation occurred in 13/22 cases. Polyps were detected in 11 procedures, with 10 having a 100% polypectomy rate, and mean caecal intubation and total procedure times were 10.4 (SD 6.2) and 30.7 minutes (SD 8.6) respectively.Patient feedback was available in 100% of cases. 20/22 patients either agreed or strongly agreed that they were satisfied with their procedure. 16/22 patients either disagreed or strongly disagreed that they experienced more pain than expected during the test. The median discomfort and pain scores (scale 0(no discomfort/pain)- 10) was 3 (IQR 1.5-4) and 2 (IQR 1-4) respectively. 16/18 patients who responded to the question, said they would be happy to undergo a further colonoscopy with penthrox.All endoscopists strongly agreed that they would be as confident in completing a procedure with penthrox as they were entonox, but more were more neutral (2 neutral, 1 agree) that they would be as confident as with IV sedation.Conclusion Despite the small cohort, this pilot study supports penthrox as a greener alternative to entonox, with acceptable patient experience and endoscopic performance, and represents the first report of its use in the UK. A larger study is planned to confirm safety, feasibility and economic evaluation for wider use.