Lung Function Changes and Exercise-Induced Ventilatory Responses to External Resistive Loads in Normal Subjects

Abstract

It is suggested that the experimental use of inspiratory and expiratory extrinsic loads can mimic rigid obstructive lesions of the larynx and trachea. Among all conventional lung function values, PEF and, to a certain degree, PIF, seem to be the best suitable follow-up parameters to assess airway mechanics before and after surgical/endoscopic procedures. Upper airway stenosis involving surface areas of no more than 50 mm2 can be overcome using adequate respiratory compensation. But any additional narrowing below this limit will result in hypoventilation, inappropriate oxygen uptake and retention of CO2. Thus, experimental evidence indicates that laryngotracheal obstruction within a critical range below 50 mm2 surface area (diameter of circular orifice < 8 mm) compromises respiratory efforts enough to be of clinical importance.