title: In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care.
abstract: There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible.
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
authors.forename: Luca
authors.initials: L
authors.lastname: Ciaffoni
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
authors.forename: David P
authors.initials: DP
authors.lastname: O'Neill
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
authors.forename: John H
authors.initials: JH
authors.lastname: Couper
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
authors.forename: Grant A D
authors.initials: GA
authors.lastname: Ritchie
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
authors.forename: Gus
authors.initials: G
authors.lastname: Hancock
authors.affiliation: Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
authors.forename: Peter A
authors.identifier: 0000-0002-4975-0609
authors.initials: PA
authors.lastname: Robbins
mesh_terms: D001014:Aortic Aneurysm / Q000503:physiopathology / Q000628:therapy*; D002245:Carbon Dioxide / Q000737:chemistry*; D003422:Critical Care; D006801:Humans; D007440:Intubation / Q000295:instrumentation; D007834:Lasers; D010100:Oxygen / Q000737:chemistry*; D010101:Oxygen Consumption; D012121:Respiration, Artificial / Q000295:instrumentation; D014867:Water / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D014867:Water; D002245:Carbon Dioxide; D010100:Oxygen
keywords: Gas lasers; absorbence spectroscopy; gas exchange; laser spectroscopy; medical device; medical technology; oxygen consumption; respiration