The effect of two techniques on the characteristics and transport of sputum in patients with bronchiectasis: A pilot study

Objective Flutter VRP1 is a device that utilises high-frequency oscillation and positive expiratory pressure to prevent mucus stasis, aid removal, and treat pulmonary atelectasis. Whether these effects are due to changes in the rheological properties of the bronchial mucus remains controversial. This pilot study examined the techniques available to determine whether the use of Flutter VRP1 in a single session by patients with bronchiectasis altered properties related to transport of tracheobronchial mucus and investigated the effect of high-frequency oscillations and positive expiratory pressure (PEP) on these alterations.

Design Pilot observational, single cohort study.

Setting Outpatient department.

Participants Eight outpatients with bronchiectasis with daily expectoration of over one tablespoon of sputum.

Intervention Participants underwent two procedures at random on different days: PEP and Flutter VRP1 exercises compared to a control (no exercise) period.

Main outcome measures Three sputum samples were collected after expectoration by voluntary coughing: at baseline, 20 and 40min after using Flutter VRP1 or PEP, or without any procedure (control). The samples were analysed on the basis of relative transport velocity, contact angle measurement and displacement in a simulated cough machine.

ResultsRelative transport velocity: The results were similar for the three groups and across the three measurements for each group, however, the measurement of transport velocity appeared relatively sensitive to change in this group (Flutter VRP1: median 0.6, 95% confidence interval 0.53–0.73; PEP: median 0.78, 95% confidence interval 0.53–0.92; control: median 0.63, 95% confidence interval 0.51–0.79). Contact angle of the mucus and displacement of the mucus in a simulated cough machine demonstrated weak trends, although these were not consistent for the three groups. Calculations based on these results illustrated the number of subjects required in a full scale clinical trial.

Conclusions The use of Flutter VRP1 and PEP by patients with bronchiectasis for up to 40min in a single session did not appear to change ciliary or cough transportability of bronchial mucus, or contact angle measurements. However, the use of these measurement techniques proved feasible in this population.