title: Evaluation of a non-invasive method of assessing opioid induced respiratory depression.
abstract: Opioid induced respiratory depression is potentially fatal. The aim of this study was to validate a monitoring system that could be used to assess respiratory depression in postoperative patients. The hypercapnic ventilatory response was estimated non-invasively in 12 volunteers. In two steps, we tested a system which delivered carbon dioxide (CO(2)) challenges through a venturi mask, measuring changes in ventilation with an uncalibrated respiratory inductance plethysmograph (RIP). RIP and pneumotachograph measurements of ventilation, taken at the same time during a CO(2) challenge, were similar; group mean (SD), pneumotachograph 13.9 (3.5) l x min(-1) x kPa(-1), RIP 14.3 (2.9) l x min(-1) x kPa(-1). Bland-Altmann analysis showed the variation between these two methods was +/- 5 l x min(-1) x kPa(-1) (2 SD). Second, we confirmed that the venturi mask is suitable for delivering CO(2) challenges. Despite the variability in RIP measurements, a simple multimodal respiratory monitoring system could be developed that incorporates clinical observation and non-invasive measurement of the ventilatory response to CO(2).
authors.affiliation: Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. kyletsp@postmaster.co.uk <kyletsp@postmaster.co.uk>
authors.forename: K T S
authors.initials: KT
authors.lastname: Pattinson
authors.forename: M
authors.initials: M
authors.lastname: Bowes
authors.forename: R G
authors.initials: RG
authors.lastname: Wise
authors.forename: M J
authors.initials: MJ
authors.lastname: Parkes
authors.forename: M J
authors.initials: MJ
authors.lastname: Morrell
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000009:adverse effects*; D002245:Carbon Dioxide; D006801:Humans; D008297:Male; D008397:Masks; D008991:Monitoring, Physiologic / Q000379:methods; D010149:Postoperative Pain / Q000188:drug therapy; D010991:Plethysmography / Q000379:methods; D011182:Postoperative Care / Q000379:methods; D012131:Respiratory Insufficiency / Q000139:chemically induced / Q000175:diagnosis*
chemical_list: D000701:Analgesics, Opioid; D002245:Carbon Dioxide