Cough is an important mechanism of airway clearance. In
patients who present weak and ineffective cough, augmentation
techniques aim to assist or simulate the maneuver. These
techniques target different phases of the cough cycle, mainly the
inspiratory and expiratory phases, through assisted inspiration,
assisted expiration and their combination. They include the
manual hyperinflation, ventilator hyperinflation, glossopharyngeal
breathing, manually assisted cough and mechanical insufflatorexsufflator, each applied individually or in different combinations.
The aim of this review is to investigate the effectiveness and
safety of cough augmentation techniques. Findings support that
all commonly used techniques can theoretically improve airway
clearance, as they generate higher cough peak flows compared
to unassisted cough. Still, the studies assessing cough
augmentation present considerable limitations and the direct
comparison of different techniques is challenging. Current
evidence indicate that cough peak flow shows higher increase
with the combination of assisted inspiration and expiration, and
improvement is greater in patients with lower unassisted values.
Associated adverse events are infrequent.
Hyperinflation is the consequence of a dysbalance of static forces (determining the relaxation volume) and/or of the dynamic components. The relaxation volume is determined by an equilibrium between the elastic recoil of the lungs and of the chest walls. The dynamic components include the pattern of breathing, upper airway resistance and postinspiratory activity of inspiratory muscles. The respiratory and laryngeal muscles are under control and thus both static and dynamic hyperinflation can be secured. Our knowledge of the mechanism of increased FRC is based on clinical observations and on experiments. The most frequent stimuli leading to a dynamic increase of functional residual lung capacity (FRC) include hypoxia and vagus afferentation. Regulation of FRC is still and undetermined concept. The controlled increase of FRC, hyperinflation, participates in a number of lung diseases., F. Paleček., and Obsahuje bibliografii