Forced expirations against a variable resistance: A new chest physiotherapy method in cystic fibrosis

Abstract

Twenty patients with cystic fibrosis (CF) were trained to mobilize intrabronchial secretions by a new method of positive expiratory pressure mask (PEP mask) physiotherapy (PT). Patients repeatedly expired forcefully through the PEP mask; expiratory resistance was varied by eight different internal diameter resistors at the outlet. Forced vital capacity with the mask (FVCPEP) was determined for each resistor and was compared with the one measured without the instrument (FVC); simultaneously the sustained expiratory pressure (SEP) developed against the resistance was recorded. After training, each patient exceeded FVC with one or more resistors; "optimum" FVCPEP was 124 +/- 16% FVC at a SEP of 61 +/- 21 cm H2O. Using the PEP mask, patients cleared a higher percentage of their daily sputum volume than with conventional PT (78 +/- 22% versus 53 +/- 17%, p less than 0.01). In 11 patients (subgroup 1), multiple aspects of lung function were measured at the beginning of the study, after 10 months with PEP mask PT, after two further months without using the mask but with conventional PT, and after six more months with PEP mask PT. Results showed significantly increased expiratory flow rates, significantly decreased hyperinflation and airway instability with PEP mask PT, and a marked decline of lung function without it. The remaining nine patients (subgroup 2) entered into the same protocol; based on findings in subgroup 1 and on ethical considerations, however, the control period without PEP mask PT was then omitted, resulting in a steady and statistically significant improvement of lung function over the entire observation period. In the course of preliminary trials, two children transiently used a suboptimal resistance (FVCPEP less than FVC) and responded with a deterioration of lung function. By dilating airways and evacuating trapped gas, this method of PEP mask PT improves lung function and mucus clearance in CF. Thorough practice with the technique and frequent control of the optimal resistance are mandatory.

Physiotherapy for airway clearance in adults

“…By using high pressures, 50±120 cmH 2 O, secretions may be mobilized more easily in patients with unstable airways [80].…”

Physiological effects of vibration in subjects with cystic fibrosis

“…The theoretical rationale of the positive expiratory pressure of these devices is to provide back pressure within the airways during expiration. This increased pressure is proposed to stabilise collapsible airways, thus increasing expiratory flow in these airways [22], and to recruit the collateral ventilation [23] allowing gas behind the secretions, thus aiding the movement of these secretions towards the oropharynx. The results of the current study cannot discount the possibility of this mechanism occurring during PEP or Acapella1.…”

Structure and Function of the Mucus Clearance System of the Lung

“…Hi-PEP uses forced expiratory maneuvers against the PEP-mask's expiratory resistor for mobilizing and transporting intrabronchial secretions (Oberwaldner et al 1986). The equipment used is the same as that described in the previous section.…”