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Updated: Aug 18, 2026
Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Evaluation of a non-invasive method of assessing opioid induced respiratory depression
K T S Pattinson1, M Bowes, R G Wise
1Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. kyletsp@postmaster.co.uk <kyletsp@postmaster.co.uk>
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).
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