Dependence of maximal flow-volume curves on time course of preceding inspiration in patients with chronic obstruction pulmonary disease
| Autor: | Joseph Milic-Emili, Edgardo D'Angelo, Luigi Marazzini, Edi Prandi |
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| Rok vydání: | 1994 |
| Předmět: |
Male
Pulmonary and Respiratory Medicine medicine.medical_specialty Vital capacity Time Factors Vital Capacity Electromyography Respiratory physiology Critical Care and Intensive Care Medicine Elastic recoil FEV1/FVC ratio Forced Expiratory Volume Internal medicine Humans Plethysmograph Medicine Lung volumes Lung Diseases Obstructive Abdominal Muscles Aged Maximal Expiratory Flow-Volume Curves Plethysmography Whole Body COPD medicine.diagnostic_test business.industry Middle Aged respiratory system medicine.disease respiratory tract diseases Surgery Respiratory Mechanics Cardiology business |
| Zdroj: | American Journal of Respiratory and Critical Care Medicine. 150:1581-1586 |
| ISSN: | 1535-4970 1073-449X |
| Popis: | Thirteen patients with chronic obstructive pulmonary disease (COPD) performed forced vital capacity (FVC) maneuvers either immediately after a rapid inspiration (maneuver 1) or after a slow inspiration with a 4- to 6-s end-inspiratory pause (maneuver 2). Seated in a body plethysmograph, they breathed through a pneumotachograph. Inspirations were initiated from resting end-expiratory lung volume. Abdominal muscle activity was recorded by means of surface electrodes. With maneuver 1: (1) expiratory flows were 20 to 40% larger in the volume range 10 to 95% FVC; (2) peak expiratory flow was on average 30% higher; and (3) FEV1, expressed as percent of FVC, increased by about 8%. No substantial differences in the pattern of abdominal muscle activity occurred between maneuvers. The dependence of maximal flow-volume curves on the time course of the preceding inspiration is probably related in part to the viscoelastic elements present within the respiratory system, which, stretched during rapid inspirations, increase the effective elastic recoil during the FVC maneuver 1. This cannot occur with maneuver 2, because of stress relaxation of the viscoelastic elements during the 4- to 6-s breathhold preceding the FVC maneuver. Other factors (e.g., time constant inequality) might also be involved. In any case, the results imply that the inspiratory maneuver prior to FVC must be standardized. |
| Databáze: | OpenAIRE |
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