Document Detail

Critical closure in the canine pulmonary vasculature.
MedLine Citation:
PMID:  7067063     Owner:  NLM     Status:  MEDLINE    
The vascular pressure-flow (P-Q) relationships in zone II (West et al.) were studied in isolated canine left lower lobes, in order to characterize the total resistance in the pulmonary vascular bed with respect to incremental or flow resistance and critical closure. At each of five levels of static lung inflation, the P-Q relationship was curvilinear at low flow and rectilinear at higher flows. The slope of the linear portion was not significantly different at alveolar pressures (PA) = 5, 7, or 9 cm H2O, but decreased significantly at PA = 11 and 15 cm H2O ((P less than 0.05), indicating an increase in flow resistance. The pulmonary artery pressure (Ppa) fell to the same value at zero flow regardless of inflation level [10.1 +/- 1.0 (SD) cm H2O at PA = 5 cm H2O to 10.9 +/- 2.7 (SD) at PA = 15 cm H2O]. The Ppa intercept (Ppai), extrapolated from the linear portion of the P-Q curve and representing the average closing pressure for the vascular bed, increased from 16.0 +/- 1.8 (SD) cm H2O at PA = 5.0 to 26.5 +/- 4.4 (SD) cm H2O at PA = 15 (P less than 0.05) in a direct one-to-one relationship with the increase in PA. Since this results in a constant transmural gradient at the alveolar vessel level, these vessels must be the major fraction which undergo critical closure. Operationally defined vascular compliance, determined from the slope of a simultaneously obtained pressure-volume (P-V) curve, decreased significantly from 1.51 +/- 0.62 (SD) ml/cm H2O at PA = 5.0 H2O to 0.87 +/- 0.27 ml/cm H2O at PA = 15 cm H2O (P less than 0.05).
R Graham; C Skoog; L Oppenheimer; J Rabson; H S Goldberg
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation research     Volume:  50     ISSN:  0009-7330     ISO Abbreviation:  Circ. Res.     Publication Date:  1982 Apr 
Date Detail:
Created Date:  1982-06-24     Completed Date:  1982-06-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0047103     Medline TA:  Circ Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  566-72     Citation Subset:  IM    
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MeSH Terms
Pulmonary Alveoli / blood supply
Pulmonary Circulation*
Pulmonary Wedge Pressure*
Vascular Resistance*

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

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