Document Detail


Pulmonary diffusing capacity in adult cystic fibrosis: reduced positional changes are partially reversed by hyperoxia.
MedLine Citation:
PMID:  2191817     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In seated adult cystic fibrosis (CF) patients, vascular recruitment of the relatively normal regions of the pulmonary circulation could occur in response to vascular destruction or hypoxia elsewhere in the pulmonary vasculature, thus limiting overall reductions in the single breath CO diffusing capacity (DLcoSB) with advancing disease. The purpose of this study was to determine the extent to which pulmonary capillary recruitment limits reductions in DLcoSB in seated adult cystic fibrosis patients, to define the role of hypoxia, and to develop strategies to improve detection of diffusion abnormalities in this disease. In normal subjects and adult CF patients breathing room air, and in a subgroup, after breathing both 40% and 100% O2 for 20 min, we measured changes (compared to sitting) in the three equation DLcoSB by changing transvascular pressure either with 15 degrees head down position (15 degrees HD), or with high negative inspiratory pressure (HNIP). In CF patients breathing room air, the changes in DLcoSB with both 15 degrees HD and HNIP were significantly smaller (p less than 0.01) than in controls and the positional changes correlated with the degree of airway obstruction. Although CF patients had no significant positional changes in diffusional resistance (1/DLcoSB) breathing room air, the positional changes in 1/DLcoSB after breathing 100% O2 for 20 min were similar in magnitude to the positional changes in normal subjects. We conclude that compensatory pulmonary capillary recruitment occurs in the relatively normal regions of the pulmonary vasculature breathing room air in the resting seated position in CF patients, thus minimizing reductions in DLcoSB in the seated position. This accounts for reduced responses of DLcoSB to both position and HNIP. The improved positional changes in 1/DLcoSB breathing hyperoxic gas mixtures in CF patients suggests that the vascular recruitment breathing room air is partly due to hypoxic vasoconstriction rather than due solely to fixed pathological changes in the pulmonary vasculature.
Authors:
D J Cotton; B L Graham; J T Mink
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical and investigative medicine. Médecine clinique et experimentale     Volume:  13     ISSN:  0147-958X     ISO Abbreviation:  Clin Invest Med     Publication Date:  1990 Apr 
Date Detail:
Created Date:  1990-07-26     Completed Date:  1990-07-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7804071     Medline TA:  Clin Invest Med     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  82-91     Citation Subset:  IM; S    
Affiliation:
Department of Medicine, University Hospital, University of Saskatchewan, Saskatoon.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Anoxia / physiopathology
Cystic Fibrosis / physiopathology*
Forced Expiratory Volume / physiology
Humans
Intermittent Positive-Pressure Breathing
Maximal Midexpiratory Flow Rate / physiology
Oxygen / physiology
Posture
Pulmonary Diffusing Capacity / physiology*
Respiration
Vasoconstriction
Vital Capacity / physiology
Chemical
Reg. No./Substance:
7782-44-7/Oxygen

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


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