Document Detail

Comparison of plethysmographic methods for obtaining thoracic gas volume in anesthetized dogs.
MedLine Citation:
PMID:  4030619     Owner:  NLM     Status:  MEDLINE    
Thoracic gas volume (TGV) cannot be measured in the body plethysmograph by the standard spontaneous breathing technique (SB) when there is a significant respiratory center depression. In this case, either external compression of the chest wall (EC) or phrenic nerve stimulation (PhN) can be used to induce the pressure-volume changes necessary to calculate TGV. In the present study we compared TGV measured in eight pentobarbital-anesthetized dogs by SB, EC, PhN, and the standard He-dilution method. EC and simulated PhN were also used to measure the volume of a lung model, and EC was used to measure the volume of isolated lung lobes. A method for fast and accurate plethysmographic calibration is also described. In the intact dogs, SB, PhN, and He-dilution techniques gave similar results, but EC overestimated TGV. In the isolated lobes and lung model EC accurately measured volume. We speculate that EC induces substantial intersegmental and/or interlobal gas movement in intact lungs and that the pressure drop due to airway resistance causes proximal airway pressure to underestimate alveolar pressure changes, which induces overestimation in calculated TGV. We conclude that PhN is the method of choice to measure plethysmographic TGV when the respiratory center is depressed and that EC overestimates TGV in intact dogs.
J A Armengol; R L Jones; E G King
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  59     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1985 Aug 
Date Detail:
Created Date:  1985-10-21     Completed Date:  1985-10-21     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  653-7     Citation Subset:  IM    
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MeSH Terms
Atmospheric Pressure
Lung Volume Measurements / methods*
Models, Biological
Phrenic Nerve / physiology
Plethysmography, Whole Body / methods*

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