New insights into physiology and pathophysiology by resistance-volume recordings.

This work deals with the assessment of airway resistance in the course of a single breath. The study showed the presence of an early increase in the resistance at the beginning of expiration, which intensifies during expiration and ends up with a sharp decline during expiring the last remaining volume of ca 350 ml. The dynamic changes in airway resistance over a breath depend on the disharmonic interplay between diaphragm function and bronchial wall tonus. Thus, airway resistance is not constant during breathing, as could be misleadingly judged from the total resistance averaged over a breath. The study underscores the importance of recording the resistance-volume curves alongside the standard flow-volume curves to be able to discern the peculiarities of airway resistance changes during a single breath. Knowing changes in the instantaneous airway resistance characteristic for a given lung pathology could appreciably improve the diagnostic and therapeutic powers.