Document Detail

Ventilation-perfusion imbalance and chronic obstructive pulmonary disease staging severity.
MedLine Citation:
PMID:  19372303     Owner:  NLM     Status:  MEDLINE    
Chronic obstructive pulmonary disease (COPD) is characterized by a decline in forced expiratory volume in 1 s (FEV(1)) and, in many advanced patients, by arterial hypoxemia with or without hypercapnia. Spirometric and gas exchange abnormalities have not been found to relate closely, but this may reflect a narrow range of severity in patients studied. Therefore, we assessed the relationship between pulmonary gas exchange and airflow limitation in patients with COPD across the severity spectrum. Ventilation-perfusion (V(A)/Q) mismatch was measured using the multiple inert gas elimination technique in 150 patients from previous studies. The distribution of patients according to the GOLD stage of COPD was: 15 with stage 1; 40 with stage 2; 32 with stage 3; and 63 with stage 4. In GOLD stage 1, AaPo(2) and V(A)/Q mismatch were clearly abnormal; thereafter, hypoxemia, AaPo(2), and V(A)/Q imbalance increased, but the changes from GOLD stages 1-4 were modest. Postbronchodilator FEV(1) was related to Pa(O(2)) (r = 0.62) and Pa(CO(2)) (r = -0.59) and to overall V(A)/Q heterogeneity (r = -0.48) (P < 0.001 each). Pulmonary gas exchange abnormalities in COPD are related to FEV(1) across the spectrum of severity. V(A)/Q imbalance, predominantly perfusion heterogeneity, is disproportionately greater than airflow limitation in GOLD stage 1, suggesting that COPD initially involves the smallest airways, parenchyma, and pulmonary vessels with minimal spirometric disturbances. That progression of V(A)/Q inequality with spirometric severity is modest may reflect pathogenic processes that reduce both local ventilation and blood flow in the same regions through airway and alveolar disease and capillary involvement.
Roberto Rodríguez-Roisin; Mitra Drakulovic; Diego A Rodríguez; Josep Roca; Joan Albert Barberà; Peter D Wagner
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-04-16
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  106     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-05-27     Completed Date:  2009-07-07     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:  1902-8     Citation Subset:  IM    
Servei de Pneumologia, Hospital Clínic, Villarroel, 170. 08036 Barcelona, Spain.
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MeSH Terms
Anoxia / diagnosis,  etiology,  physiopathology
Chronic Disease
Disease Progression
Middle Aged
Pulmonary Disease, Chronic Obstructive* / classification,  complications,  diagnosis,  physiopathology
Respiratory Insufficiency / diagnosis,  etiology,  physiopathology
Severity of Illness Index*
Ventilation-Perfusion Ratio*

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