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Problems in timing of respiration with the nasal thermistor technique.
Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
Linköping University, Department of Biomedical Engineering.
Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
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1993 (English)In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 6, no 2, 210-216 p.Article in journal (Refereed) Published
Abstract [en]

When one analyzes transvalvular and venous flow velocity patterns, it is important to relate them to respiration. For this reason a nasal thermistor technique is often used, although it is known that this signal is delayed in relation to intrathoracic pressure changes. The magnitude and variation in delay have not been investigated previously and were, therefore, studied in a model experiment in 10 normal subjects, in 10 patients with obstructive, and in 10 patients with restrictive pulmonary disease. Esophageal pressure variations measured with an air-filled balloon served as a gold standard for intrathoracic pressure changes. During basal conditions there was, for both patient groups and normal subjects, a considerable delay of the thermistor signal. The average delay for all subjects was 370 msec with a wide variation (from 120 to 720 msec). At higher breathing frequencies the delay shortened to 310 msec (P < 0.01) but there was still a wide variation (ranging from 200 to 470 msec). Theoretic calculations show that the delay caused by the respiratory system accounts for only a minor portion of the total delay. Model experiments confirmed that the response characteristics of the thermistor probes limit the accuracy in timing of respiration. The total delay with the investigated thermistor technique is too long and variable to fulfil clinical demands.

Place, publisher, year, edition, pages
1993. Vol. 6, no 2, 210-216 p.
National Category
Medical Laboratory and Measurements Technologies
URN: urn:nbn:se:liu:diva-116999PubMedID: 8481251OAI: diva2:801930
Available from: 2015-04-10 Created: 2015-04-10 Last updated: 2015-04-22

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Sjöberg, Birgitta JaneroSveider, PerAsk, PerLoyd, DanWranne, Bengt
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Clinical PhysiologyFaculty of Health SciencesCenter for Medical Image Science and Visualization (CMIV)Department of Clinical Physiology in LinköpingDepartment of Biomedical EngineeringPhysiological MeasurementsThe Institute of TechnologyApplied Thermodynamics and Fluid MechanicsClinical Physiology
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Journal of the American Society of Echocardiography
Medical Laboratory and Measurements Technologies

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