Studies on alveolar ventilation, gaseous diffusion, and the mechanical events of breathing have been extensively explored over the last two decades.
Airway obstruction is the common cause of dyspnea of pulmonary origin. According to Gainsler and Lindgren,1 obstruction may be at the bronchiolar level, and when it occurs intermittently due to increased tone of the bronchial musculature or edema of the bronchial mucosa or both, the picture is one of bronchial asthma. When the obstruction is more or less continuous, appears irreversible, and is associated with distal lung pathology, chronic obstructive emphysema is the most likely diagnosis.
A number of tests have been developed to aid in the detection of defects in the mechanics of breathing. These basically involve measurement of expiratory and inspiratory air flow mechanisms. Quiet expiration is thought of as a passive act accomplished by potential energy stored in the elastic tissues of the lungs during
Cass LJ. Measurement of Total Respiratory and Nasal Airflow Resistance. JAMA. 1967;199(6):396–398. doi:10.1001/jama.1967.03120060094016
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