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A novel application of capnography during controlled human exposure to air pollution

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11 pages
The objective was to determine the repeatability and stability of capnography interfaced with human exposure facility. Methods Capnographic wave signals were obtained from five healthy volunteers exposed to particle-free, filtered air during two consecutive 5 min intervals, 10 min apart, within the open and then the sealed and operational human exposure facility (HEF). Using a customized setup comprised of the Oridion Microcap ® portable capnograph, DA converter and AD card, the signal was acquired and saved as an ASCII file for subsequent processing. The minute ventilation (VE), respiratory rate (RR) and expiratory tidal volume (V TE ) were recorded before and after capnographic recording and then averaged. Each capnographic tracing was analyzed for acceptable waves. From each recorded interval, 8 to 19 acceptable waves were selected and measured. The following wave parameters were obtained: total length and length of phase II and III, slope of phase II and III, area under the curve and area under phase III. In addition, we recorded signal measures including the mean, standard deviation, mode, minimum, maximum – which equals end-tidal CO 2 (EtCO 2 ), zero-corrected maximum and true RMS. Results Statistical analysis using a paired t-test for means showed no statistically significant changes of any wave parameters and wave signal measures, corrected for RR and V TE , comparing the measures when the HEF was open vs. sealed and operational. The coefficients of variation of the zero-corrected and uncorrected EtCO 2 , phase II absolute difference, signal mean, standard deviation and RMS were less than 10% despite a sub-atmospheric barometric pressure, and slightly higher temperature and relative humidity within the HEF when operational. Conclusion We showed that a customized setup for the acquisition and processing of the capnographic wave signal, interfaced with HEF was stable and repeatable. Thus, we expect that analysis of capnographic waves in controlled human air pollution exposure studies is a feasible tool for characterization of cardio-pulmonary effects of such exposures.
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BioMedical Engineering OnLine
BioMedCentral
Open Access Research A novel application of capnography during controlled human exposure to air pollution 1 1,2 1,5 4,6 Karl Z Lukic* , Bruce Urch , Michael Fila , Marie E Faughnan and 1,3,4 Frances Silverman
1 2 Address: Gage Occupational and Environmental Health Unit, St. Michael's Hospital & University of Toronto, Toronto, ON, Canada, Institute of 3 Medical Sciences, University of Toronto, Toronto, ON, Canada, Department of Public Health Sciences, University of Toronto, Toronto, ON, 4 5 Canada, Department of Medicine, University of Toronto, Toronto, ON, Canada, Department of Chemical Engineering, University of Toronto, 6 Toronto, ON, Canada and Division of Respiratory Medicine, Department of Medicine, St. Michael's Hospital, Toronto, ON, Canada Email: Karl Z Lukic*  z.lukic@utoronto.ca; Bruce Urch  bruce.urch@utoronto.ca; Michael Fila  mfila47@hotmail.com; Marie E Faughnan  faughnanm@smh.toronto.on.ca; Frances Silverman  frances.silverman@utoronto.ca * Corresponding author
Published: 18 October 2006 Received: 02 May 2006 Accepted: 18 October 2006 BioMedical Engineering OnLine2006,5:54 doi:10.1186/1475-925X-5-54 This article is available from: http://www.biomedical-engineering-online.com/content/5/1/54 © 2006 Lukic et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background:The objective was to determine the repeatability and stability of capnography interfaced with human exposure facility. Methods:Capnographic wave signals were obtained from five healthy volunteers exposed to particle-free, filtered air during two consecutive 5 min intervals, 10 min apart, within the open and then the sealed and operational human exposure facility (HEF). Using a customized setup ® comprised of the Oridion Microcap portable capnograph, DA converter and AD card, the signal was acquired and saved as an ASCII file for subsequent processing. The minute ventilation (VE), respiratory rate (RR) and expiratory tidal volume (V ) were recorded before and after TE capnographic recording and then averaged. Each capnographic tracing was analyzed for acceptable waves. From each recorded interval, 8 to 19 acceptable waves were selected and measured. The following wave parameters were obtained: total length and length of phase II and III, slope of phase II and III, area under the curve and area under phase III. In addition, we recorded signal measures including the mean, standard deviation, mode, minimum, maximum – which equals end-tidal CO 2 (EtCO ), zero-corrected maximum and true RMS. 2 Results:Statistical analysis using a paired t-test for means showed no statistically significant changes of any wave parameters and wave signal measures, corrected for RR and V , comparing TE the measures when the HEF was open vs. sealed and operational. The coefficients of variation of the zero-corrected and uncorrected EtCO , phase II absolute difference, signal mean, standard 2 deviation and RMS were less than 10% despite a sub-atmospheric barometric pressure, and slightly higher temperature and relative humidity within the HEF when operational. Conclusion:We showed that a customized setup for the acquisition and processing of the capnographic wave signal, interfaced with HEF was stable and repeatable. Thus, we expect that analysis of capnographic waves in controlled human air pollution exposure studies is a feasible tool for characterization of cardio-pulmonary effects of such exposures.
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