Document Detail

Canine thoracic electrical impedance with changes in pulmonary gas and blood volumes.
MedLine Citation:
PMID:  7153157     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to evaluate transthoracic impedance (Z) as an index of total lung liquid content at constant lung gas volume (LGV). To this end we produced rapid changes in pulmonary blood volume (PBV) in anesthetized, paralyzed, closed-chest dogs with the airway occluded at functional residual capacity. Changes in PBV produced by inflation of balloons on catheters positioned in the left atrium (LA) or inferior vena cava (IVC) were estimated from the changes in chest wall recoil pressure, using the chest wall as a plethysmograph after calibration with changes in LGV. Whereas Z increased linearly with decreases in PBV (1-6 ml/kg) produced by the IVC balloon (% delta Z/delta PBV = -0.43 ml/kg, r = -0.81), Z did not change significantly with increases in PBV (1-6 ml/kg) produced by the LA balloon. These observations indicate that changes in PBV are not the primary determinant of changes in Z and raise the possibility that other hemodynamic events are more important. Whereas aortic pressure decreased with both IVC and LA balloon inflations, right atrial pressure (Pra) increased with mitral valve obstruction and decreased with IVC obstruction. Changes in chest wall blood volume in response to changes in Pra could explain the changes in thoracic impedance. Thus, even at constant LGV, events in the systemic circulation appear to invalidate Z as an indicator of lung liquid content.
R M Smith; B A Gray
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  53     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1982 Dec 
Date Detail:
Created Date:  1983-03-11     Completed Date:  1983-03-11     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1608-13     Citation Subset:  IM    
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MeSH Terms
Blood Volume*
Cardiography, Impedance*
Functional Residual Capacity
Lung Compliance
Lung Volume Measurements*
Plethysmography, Impedance*
Pulmonary Circulation*
Pulmonary Edema / diagnosis

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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