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Fleming L, Gibson D, Hutson D, Ahmadzadeh S, Waddell E, Song S, Reid S, Clark C, Baker JS, Overend R, MacGregor C. Breath emulator for simulation and modelling of expired tidal breath carbon dioxide characteristics. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 200:105826. [PMID: 33187733 DOI: 10.1016/j.cmpb.2020.105826] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND In this work we describe a breath emulator system, used to simulate temporal characteristics of exhaled carbon dioxide (CO2) concentration waveform versus time simulating how much CO2 is present at each phase of the human lung respiratory process. The system provides a method for testing capnometers incorporating fast response non-dispersive infrared (NDIR) CO2 gas sensing devices - in a clinical setting, capnography devices assess ventilation which is the CO2 movement in and out of the lungs. A mathematical model describing the waveform of the expired CO2 characteristic and influence of CO2 gas sensor noise factors and speed of response is presented and compared with measured and emulated data. OBJECTIVE A range of emulated capnogram temporal waveforms indicative of normal and restricted respiratory function demonstrated. The system can provide controlled introduction of water vapour and/ or other gases, simulating the influence of water vapour in exhaled breath and presence of other gases in a clinical setting such as anaesthetic agents (eg N2O). This enables influence of water vapour and/ or other gases to be assessed and modelled in the performance of CO2 gas sensors incorporated into capnography systems. As such the breath emulator provides a means of controlled testing of capnometer CO2 gas sensors in a non-clinical setting, allowing device optimisation before use in a medical environment. METHODS The breath emulator uses a unique combination of mass flow controllers, needle valves and a fast acting switchable pneumatic solenoid valve (FASV), used to controllably emulate exhaled CO2 temporal waveforms for normal and restricted respiratory function. Output data from the described emulator is compared with a mathematical model using a range of input parameters such as time constants associated with inhalation/ exhalation for different parts of the respiratory cycle and CO2 concentration levels. Sensor noise performance is modelled, taking into account input parameters such as sampling period, sensor temperature, sensing light throughput and pathlength. RESULTS The system described here produces realistic human capnographic waveforms and has the capability to emulate various waveforms associated with chronic respiratory diseases and early stage detection of exacerbations. The system has the capability of diagnosing medical conditions through analysis of CO2 waveforms. Demonstrated in this work the emulator has been used to test NDIR gas sensor technology deployed in capnometer devices prior to formal clinical trialling.
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Affiliation(s)
- Lewis Fleming
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - Des Gibson
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - David Hutson
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - Sam Ahmadzadeh
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - Ewan Waddell
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - Shigeng Song
- Institute of Thin Films, Sensors and Imaging, School of Engineering and Computing, University of the West of Scotland, PA1 2BE Paisley, Scotland, UK.
| | - Stuart Reid
- The department of Biomedical Engineering, Graham Hills Building, The University of Strathclyde, 50 George Street, Glasgow, G1 1QE, UK.
| | - Caspar Clark
- Helia Photonics Ltd, Unit 2, Rosebank Technology Park, Livingston, EH54 7EJ, UK.
| | - Julien S Baker
- Hong Kong Baptist University, Kowloon Tong, Hong Kong, P R China.
| | - Russell Overend
- Wideblue Ltd, Kelvin Campus, West of Scotland Science Park, Glasgow, G20 0SP.
| | - Calum MacGregor
- Gas Sensing Solutions Ltd, Westfield North Courtyard, Glasgow G68 9HQ, UK.
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Singh OP, Kumarasamy R, nur binti abd Hamid Z, Malarvili MB. Identification of Asthmatic Patient During Exercise Using Feature Extraction of Carbon Dioxide Waveform. 2019 IEEE INTERNATIONAL CONFERENCE ON SIGNAL AND IMAGE PROCESSING APPLICATIONS (ICSIPA) 2019. [DOI: 10.1109/icsipa45851.2019.8977740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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Yang J, Wang H, Chen B, Wang B, Wang L. Use of signal decomposition to compensate for respiratory disturbance in mainstream capnometer. APPLIED OPTICS 2014; 53:2145-2151. [PMID: 24787173 DOI: 10.1364/ao.53.002145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 02/24/2014] [Indexed: 06/03/2023]
Abstract
End-tidal carbon dioxide (P(ET)CO₂) monitoring has become an important tool in clinical monitoring, but there are still limitations in practice. Low-frequency modulation was used to reliably acquire respiratory information. Then the disturbances of humidity and flow rate were removed by signal decomposition. Finally, the real-time concentration of CO₂ was calculated and displayed by an adjusted calibration function. Targeted experiments confirm that a period of 180 ms and a depth of 50% was the optimal choice. In this case, the effects of humidity and flow rate reflected by different components were removed effectively from the capnography. This capnometer obtains capnography with excellent accuracy and stability in long-term continuous monitoring.
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Jiachen Yang, Bin Wang, Ran Xu, Lei Wang. A new real-time and precision capnography for human respiration carbon dioxide concentration. Perfusion 2010; 25:399-408. [PMID: 20696739 DOI: 10.1177/0267659110380772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper is a description of the designing of a new mainstream device to measure human respiration carbon dioxide concentration, based on non-dispersive infrared (NDIR) absorption technology. The device can be used to accurately monitor the cardiopulmonary status during anaesthesia and mechanical ventilation in real time. This new device can not only make up the error of real-time gas measurement of the side-stream device, but also make up the accuracy of the main-stream device. In the paper, four issues which can affect the measurement accuracy were considered: respiration gas flow, turbulence of the light source with all ranges of wavelength, temperature drift and signal noise. The experimental results showed that the device could produce a stable output signal and deviation of measurement accuracy could be achieved to within 4%.
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Affiliation(s)
- Jiachen Yang
- School of Electronic Information Engineering, Tianjin University, Tianjin, China.
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Folke M. Estimation of the lactate threshold using an electro acoustic sensor system analysing the respiratory air. Med Biol Eng Comput 2008; 46:939-42. [PMID: 18651190 DOI: 10.1007/s11517-008-0373-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 06/26/2008] [Indexed: 11/30/2022]
Abstract
The lactate threshold is used by athletes to optimise the intensity during exercise. It is of interest to measure the threshold on the very day and during the present sport activity. Steady state ergometer tests have been performed on 40 individuals to compare the threshold found by an electro acoustic sensor system to the lactate threshold established by blood analyses evaluated with the Dmax method. The correlation coefficient between the threshold found by the sensor system and the one established by blood analyses regarding workload (Watt), heart rate (beats/min), and lactate level (mmol lactate/l blood) at the thresholds were 0.87 (p < 0.001), 0.74 (p < 0.001), and 0.65 (p < 0.001), respectively. The findings in this study indicates that the thresholds of individuals measured by the sensor system show good correlations to the threshold established with the Dmax method from lactate levels in blood samples.
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Affiliation(s)
- M Folke
- School of Innovation, Design and Engineering, Mälardalen University, Vasteras, Sweden.
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