Measurement validity of an electronic training device to assess breathing characteristics during inspiratory muscle training in patients with weaning difficulties

Abstract

Inspiratory muscle training (IMT) improves respiratory muscle function and might enhance weaning outcomes in patients with weaning difficulties. An electronic inspiratory loading device provides valid, automatically processed information on breathing characteristics during IMT sessions. Adherence to and quality of IMT, as reflected by work of breathing and power generated by inspiratory muscles, are related to improvements in inspiratory muscle function in patients with chronic obstructive pulmonary disease. The aim of this study was to investigate the validity of an electronic training device to assess and provide real-time feedback on breathing characteristics during inspiratory muscle training (IMT) in patient with weaning difficulties. Patients with weaning difficulties performed daily IMT sessions against a tapered flow-resistive load of approximately 30 to 50% of the patient's maximal inspiratory pressure. Airflow and airway pressure measurements were simultaneously collected with the training device (POWERbreatheKH2, POWERbreathe International Ltd, UK) and a portable spirometer (reference device, Pocket-Spiro USB/BT100, M.E.C, Belgium). Breath by breath analysis of 1002 breaths of 27 training sessions (n = 13) against a mean load of 46±16% of the patient's maximal inspiratory pressure were performed. Good to excellent agreement (Intraclass correlation coefficients: 0.73-0.97) was observed for all breathing characteristics. When individual differences were plotted against mean values of breaths recorded by both devices, small average biases were observed for all breathing characteristics. To conclude, the training device provides valid assessments of breathing characteristics to quantify inspiratory muscle effort (e.g. work of breathing and peak power) during IMT in patients with weaning difficulties. Availability of valid real-time data of breathing responses provided to both the physical therapist and the patient, can be clinically usefull to optimize the training stimulus. By adapting the external load based on the visual feedback of the training device, respiratory muscle work and power generation during IMT can be maximized during the training.

Conflict of interest statement

I have read the journal’s policy and the authors of this manuscript have the following competing interests: the POWERbreathe KH2 devices, used in this study were provided by HAB - POWERbreathe International Ltd., (Warwickshire, England) for study purposes at no additional cost. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Setup of measurements.

Inspiratory muscle training was performed with the portable spirometer placed between the electronic inspiratory training device (Panel A) and connected to the patient either via an endotracheal tube or via a tracheostomy (Panel B).

Fig 2. Visual feedback.

Real-time visual feedback on breathing characteristics are provided by the Breathe-Link software. In the upper left corner, the amount of inspirations that have been performed against the set inspiratory load is indicated. The general settings of the training are depicted in in upper right corner. In the middle of the screen the pointer indicates the peak power that is performed in the last inspiration. On the left of the pointer the peak flow and on the right of the pointer the inspiratory tidal volume of the last inspiration are shown. In the bars below the mean power and the inspiratory tidal volume of all breaths performed in the session are depecited.

Fig 3. Breathing characteristics: Bland-Altman plots.

Agreement between estimates of several breathing characteristics of individual breaths performed during inspiratory muscle training as assessed by the portable spirometer and the electronic inspiratory training device. LoA = Limit of Agreement.