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Formenti F, Bommakanti N, Chen R, Cronin JN, McPeak H, Holopherne-Doran D, Hedenstierna G, Hahn CEW, Larsson A, Farmery AD. Respiratory oscillations in alveolar oxygen tension measured in arterial blood. Sci Rep 2017; 7:7499. [PMID: 28878215 PMCID: PMC5587703 DOI: 10.1038/s41598-017-06975-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 06/20/2017] [Indexed: 01/02/2023] Open
Abstract
Arterial oxygen partial pressure can increase during inspiration and decrease during expiration in the presence of a variable shunt fraction, such as with cyclical atelectasis, but it is generally presumed to remain constant within a respiratory cycle in the healthy lung. We measured arterial oxygen partial pressure continuously with a fast intra-vascular sensor in the carotid artery of anaesthetized, mechanically ventilated pigs, without lung injury. Here we demonstrate that arterial oxygen partial pressure shows respiratory oscillations in the uninjured pig lung, in the absence of cyclical atelectasis (as determined with dynamic computed tomography), with oscillation amplitudes that exceeded 50 mmHg, depending on the conditions of mechanical ventilation. These arterial oxygen partial pressure respiratory oscillations can be modelled from a single alveolar compartment and a constant oxygen uptake, without the requirement for an increased shunt fraction during expiration. Our results are likely to contribute to the interpretation of arterial oxygen respiratory oscillations observed during mechanical ventilation in the acute respiratory distress syndrome.
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Affiliation(s)
- Federico Formenti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom. .,Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom.
| | - Nikhil Bommakanti
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Rongsheng Chen
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - John N Cronin
- Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Hanne McPeak
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | | | | | - Clive E W Hahn
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Anders Larsson
- Department of Surgical Sciences, University of Uppsala, Uppsala, Sweden
| | - Andrew D Farmery
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
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Formenti F, Chen R, McPeak H, Murison PJ, Matejovic M, Hahn CEW, Farmery AD. Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome. Br J Anaesth 2015; 114:683-8. [PMID: 25631471 PMCID: PMC4364062 DOI: 10.1093/bja/aeu407] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 (PaO2) can vary within the respiratory cycle in cyclical atelectasis (CA), where PaO2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these PaO2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen (FIO2) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of PaO2 values in vivo. We also hypothesized that the sensor could measure rapid intra-breath PaO2 oscillations in a large animal model of ARDS. Results In the healthy animal models, PaO2 responses to changes in FIO2 were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of PaO2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected PaO2 oscillations, also at clinically relevant PaO2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic PaO2 sensors have the potential to become a diagnostic tool for CA in ARDS.
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Affiliation(s)
- F Formenti
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - R Chen
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - H McPeak
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - P J Murison
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - M Matejovic
- Biomedical Centre, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic First Medical Department, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic
| | - C E W Hahn
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
| | - A D Farmery
- Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford, UK
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Chemonges S, Shekar K, Tung JP, Dunster KR, Diab S, Platts D, Watts RP, Gregory SD, Foley S, Simonova G, McDonald C, Hayes R, Bellpart J, Timms D, Chew M, Fung YL, Toon M, Maybauer MO, Fraser JF. Optimal management of the critically ill: anaesthesia, monitoring, data capture, and point-of-care technological practices in ovine models of critical care. BIOMED RESEARCH INTERNATIONAL 2014; 2014:468309. [PMID: 24783206 PMCID: PMC3982457 DOI: 10.1155/2014/468309] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/21/2014] [Accepted: 02/10/2014] [Indexed: 12/18/2022]
Abstract
Animal models of critical illness are vital in biomedical research. They provide possibilities for the investigation of pathophysiological processes that may not otherwise be possible in humans. In order to be clinically applicable, the model should simulate the critical care situation realistically, including anaesthesia, monitoring, sampling, utilising appropriate personnel skill mix, and therapeutic interventions. There are limited data documenting the constitution of ideal technologically advanced large animal critical care practices and all the processes of the animal model. In this paper, we describe the procedure of animal preparation, anaesthesia induction and maintenance, physiologic monitoring, data capture, point-of-care technology, and animal aftercare that has been successfully used to study several novel ovine models of critical illness. The relevant investigations are on respiratory failure due to smoke inhalation, transfusion related acute lung injury, endotoxin-induced proteogenomic alterations, haemorrhagic shock, septic shock, brain death, cerebral microcirculation, and artificial heart studies. We have demonstrated the functionality of monitoring practices during anaesthesia required to provide a platform for undertaking systematic investigations in complex ovine models of critical illness.
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Affiliation(s)
- Saul Chemonges
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia ; Medical Engineering Research Facility (MERF), Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - Kiran Shekar
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia ; Bond University, Gold Coast, QLD 4226, Australia
| | - John-Paul Tung
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; Research and Development, Australian Red Cross Blood Service, Kelvin Grove, Brisbane, QLD 4059, Australia
| | - Kimble R Dunster
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - Sara Diab
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - David Platts
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Ryan P Watts
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; Department of Emergency Medicine, Princess Alexandra Hospital, 199 Ipswich Road, Woolloongabba, QLD 4102, Australia
| | - Shaun D Gregory
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia ; Innovative Cardiovascular Engineering and Technology Laboratory, The Prince Charles Hospital, Chermside, Brisbane, QLD 4032, Australia
| | - Samuel Foley
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Gabriela Simonova
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Charles McDonald
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Rylan Hayes
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Judith Bellpart
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Daniel Timms
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; Innovative Cardiovascular Engineering and Technology Laboratory, The Prince Charles Hospital, Chermside, Brisbane, QLD 4032, Australia
| | - Michelle Chew
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia
| | - Yoke L Fung
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Michael Toon
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia
| | - Marc O Maybauer
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - John F Fraser
- Critical Care Research Group Laboratory, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD 4032, Australia ; The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia ; Innovative Cardiovascular Engineering and Technology Laboratory, The Prince Charles Hospital, Chermside, Brisbane, QLD 4032, Australia
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Formenti F, Chen R, McPeak H, Matejovic M, Farmery AD, Hahn CEW. A fibre optic oxygen sensor that detects rapid PO2 changes under simulated conditions of cyclical atelectasis in vitro. Respir Physiol Neurobiol 2013; 191:1-8. [PMID: 24184746 PMCID: PMC3906517 DOI: 10.1016/j.resp.2013.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/11/2013] [Accepted: 10/14/2013] [Indexed: 12/02/2022]
Abstract
Real time detection of cyclical atelectasis is fundamental for individualised mechanical-ventilation therapy in ARDS. Intra-arterial oxygen sensors could be used to detect the breath-by-breath oscillations in PO2 during cyclical atelectasis. The fidelity with which oxygen sensors can detect these arterial PO2 oscillations depends on the sensors’ speed of response. We present a system for testing fast-response fibre optic oxygen sensors under simulated conditions of cyclical atelectasis. We show that a prototype fibre optic oxygen sensor, compatible with clinical use, can detect rapid PO2 changes in vitro.
Two challenges in the management of Acute Respiratory Distress Syndrome are the difficulty in diagnosing cyclical atelectasis, and in individualising mechanical ventilation therapy in real-time. Commercial optical oxygen sensors can detect PaO2 oscillations associated with cyclical atelectasis, but are not accurate at saturation levels below 90%, and contain a toxic fluorophore. We present a computer-controlled test rig, together with an in-house constructed ultra-rapid sensor to test the limitations of these sensors when exposed to rapidly changing PO2 in blood in vitro. We tested the sensors’ responses to simulated respiratory rates between 10 and 60 breaths per minute. Our sensor was able to detect the whole amplitude of the imposed PO2 oscillations, even at the highest respiratory rate. We also examined our sensor's resistance to clot formation by continuous in vivo deployment in non-heparinised flowing animal blood for 24 h, after which no adsorption of organic material on the sensor's surface was detectable by scanning electron microscopy.
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Affiliation(s)
- Federico Formenti
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - Rongsheng Chen
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Hanne McPeak
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Martin Matejovic
- Biomedical Centre, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic; First Medical Department, Charles University in Prague, Faculty of Medicine in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic
| | - Andrew D Farmery
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Clive E W Hahn
- Nuffield Division of Anaesthetics, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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