Portable inhaled methoxyflurane is feasible and safe for colonoscopy in subjects with morbid obesity and/or obstructive sleep apnea

Background and study aims: Colonoscopy with inhaled methoxyflurane (Penthrox) is well tolerated in unselected subjects and is not associated with respiratory depression. The aim of this prospective study was to compare the feasibility, safety, and post-procedural outcomes of portable methoxyflurane used as an analgesic agent during colonoscopy with those of anesthesia-assisted deep sedation (AADS) in subjects with morbid obesity and/or obstructive sleep apnea (OSA).

Patients and methods: The outcomes of 140 patients with morbid obesity/OSA who underwent colonoscopy with either Penthrox inhalation (n = 85; 46 men, 39 women; mean age 57.2 ± 1.1 years) or AADS (n = 55; 27 men, 28 women; mean age, 54.9 ± 1.1 years) were prospectively assessed.

Results: All Penthrox-assisted colonoscopies were successful, without any requirement for additional intravenous sedation. Compared with AADS, Penthrox was associated with a shorter total procedural time (24 ± 1 vs. 52 ± 1 minutes, P < 0.001), a lower incidence of hypotension (3 /85 vs. 23 /55, P < 0.001), and a lower incidence of respiratory desaturation (0 /85 vs. 14 /55, P < 0.001). The patients in the Penthrox group recovered more rapidly and were discharged much earlier than those in the AADS group (27 ± 2 vs. 97 ± 5 minutes, P < 0.0001). Of those who underwent colonoscopy with Penthrox, 90 % were willing to receive Penthrox again for colonoscopy. More importantly, of the patients who underwent colonoscopy with Penthrox and had had AADS for previous colonoscopy, 82 % (28 /34) preferred to receive Penthrox for future colonoscopies. Penthrox-assisted colonoscopy cost significantly less than colonoscopy with AADS ($ 332 vs. $ 725, P < 0.001), with a cost saving of approximately $ 400 for each additional complication avoided.

Conclusions: Compared with AADS, Penthrox is highly feasible and safe in patients with morbid obesity/OSA undergoing colonoscopy and is associated with fewer cardiorespiratory complications. Because of the advantages of this approach in regard to procedural time, recovery time, and cost benefit in comparison with AADS, further evaluation in a randomized trial is warranted.

• References

• 1 Bourke MJ. Making every colonoscopy count: ensuring quality in endoscopy. J Gastroenterol Hepatol 2009; 24: S43-S50
• 2 Jover R, Herraiz M, Alarcon O et al. Clinical practice guidelines: quality of colonoscopy in colorectal cancer screening. Endoscopy 2012; 44: 444-451
• 3 Cohen LB. Sedation issues in quality colonoscopy. Gastrointest Endosc Clin N Am 2010; 20: 615-627
• 4 Hayee B, Dunn J, Loganayagam A et al. Midazolam with meperidine or fentanyl for colonoscopy: results of a randomized trial. Gastrointest Endosc 2009; 69: 681-687
• 5 Bannert C, Reinhart K, Dunkler D et al. Sedation in screening colonoscopy: impact on quality indicators and complications. Am J Gastroenterol 2012; 107: 1837-1848
• 6 Ladas SD, Satake Y, Mostafa I et al. Sedation practices for gastrointestinal endoscopy in Europe, North America, Asia, Africa and Australia. Digestion 2010; 82: 74-76
• 7 Nguyen NQ, Toscano L, Lawrence M et al. Patient-controlled analgesia with inhaled methoxyflurane versus conventional endoscopist-provided sedation for colonoscopy: a randomized multicenter trial. Gastrointest Endosc 2013; 78: 892-901
• 8 Toomath RJ, Morrison RB. Renal failure following methoxyflurane analgesia. N Z Med J 1987; 100: 707-708
• 9 Rubinger D, Davidson JT, Melmed RN. Hepatitis following the use of methoxyflurane in obstetric analgesia. Anesthesiology 1975; 43: 593-595
• 10 Grindlay J, Babl FE. Review article: Efficacy and safety of methoxyflurane analgesia in the emergency department and prehospital setting. Emerg Med Australas 2009; 21: 4-11
• 11 Australian Government, Department of Health, Therapeutic Goods Administration. Medicines Safety Update. Volume 5 Number 2, April 2014, Available from: https://www.tga.gov.au/publication-issue/medicines-safety-update-volume-5-number-2-april-2014. Accessed May 14, 2015 2014
• 12 Bendall JC, Simpson PM, Middleton PM. Prehospital analgesia in New South Wales, Australia. Prehosp Disaster Med 2011; 26: 422-426
• 13 Johnston S, Wilkes GJ, Thompson JA et al. Inhaled methoxyflurane and intranasal fentanyl for prehospital management of visceral pain in an Australian ambulance service. Emerg Med J 2011; 28: 57-63
• 14 Buntine P, Thom O, Babl F et al. Prehospital analgesia in adults using inhaled methoxyflurane. Emerg Med Australas 2007; 19: 509-514
• 15 Chen PJ, Li CH, Huang TY et al. Carbon dioxide insufflation does not reduce pain scores during colonoscope insertion in unsedated patients: a randomized, controlled trial. Gastrointest Endosc 2013; 77: 79-89
• 16 Iwata N, Mishima N, Shimizu T et al. Positive and negative affect in the factor structure of the State-Trait Anxiety Inventory for Japanese workers. Psychol Rep 1998; 82: 651-656
• 17 Spielberger CD, Vagg PR. Psychometric properties of the STAI: a reply to Ramanaiah, Franzen, and Schill. J Pers Assess 1984; 48: 95-97
• 18 Dahlgren G, Irestedt L. The definition of hypotension affects its incidence. Acta Anaesthesiol Scand 2010; 54: 907-908
• 19 Horiuchi A, Nakayama Y, Kajiyama M et al. Safety and effectiveness of propofol sedation during and after outpatient colonoscopy. World J Gastroenterol 2012; 18: 3420-3425
• 20 Sipe BW, Rex DK, Latinovich D et al. Propofol versus midazolam/meperidine for outpatient colonoscopy: administration by nurses supervised by endoscopists. Gastrointest Endosc 2002; 55: 815-825
• 21 Plummer JL, Hall PD, Jenner MA et al. Hepatic and renal effects of prolonged exposure of rats to 50 p.p.m. methoxyflurane. . Acta Pharmacol Toxicol 1985; 57: 176-183
• 22 Abdullah WA, Sheta SA, Nooh NS. Inhaled methoxyflurane (Penthrox) sedation for third molar extraction: a comparison to nitrous oxide sedation. Aust Dent J 2011 2011; 56: 296-301