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Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
[External resistances and dyspnea. Value of the study of flow-volume loops]
L Barthélémy1, P Mialon, P Sébert
1Service d'Explorations Fonctionnelles Respiratoires Lavoisier, CHRU Morvan, Brest.
Abstract:
Breathlessness induced by external resistances (diaphragms with orifice size of 20, 15, 10, 7.5 and 5 mm) introduced in the ventilatory circuit of a spirometer and the corresponding parameters of a maximal flow-volume loop have been studied. 10 healthy subjects (5 men, 5 women), free from any acute or chronic cardiorespiratory disease, volunteered for this study. The results showed that the breathlessness (severe or moderate) was especially correlated with the decrease in peak flows, peak inspiratory flow (PIF) more than peak expiratory flow (PEF): when breathlessness was moderate, PIF was more decreased than PEF, -35% and -28% respectively; when breathlessness became severe, PIF also decreased more than PEF, -60% and -50% respectively; forced vital capacity (FVC) never changed and maximal expiratory flows at 50% and 25% of FVC were only slightly modified despite obvious breathlessness. The increase in diaphragmatic activity seemed more implicated than the activation of expiratory muscles in the genesis of breathlessness. PIF more than the commoner PEF could be a useful marker of the breathlessness perceived by the patient during acute bronchial obstruction (asthma).
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