Low-Cost Open-Source Device to Measure Maximal Inspiratory and Expiratory Pressures.

Claudia Aymerich,Jorge Otero,Miguel Rodríguez-Lázaro,Ramon Farré,Gorka Solana

doi:10.3389/fphys.2021.719372

Abstract

The measurement of maximal inspiratory (MIP) and maximal expiratory (MEP) pressures is a widely used technique to non-invasively evaluate respiratory muscle strength in clinical practice. The commercial devices that perform this test range from whole body plethysmographs to portable spirometers, both expensive and include a wide range of other respiratory tests. Given that a portable, low-cost, and specific option for MIP and MEP measuring device is not currently available in the market. A high-performance and easy-to-build prototype has been developed and the detailed technical information to easily reproduce it is freely released. A novel device is based on an Arduino microcontroller with a digital display, an integrated pressure transducer, and three-dimensional (3D) printed enclosure (total retail cost €80). The validation of the device was performed by comparison with a laboratory reference setting, and results showed accuracy within ±1%. As the device design is available according to the open-source hardware approach, measuring MIP/MEP can greatly facilitate easily available point-of-care devices for the monitoring of patients and, most important, for making this lung function measurement tool affordable to users in low- and middle-income countries.

Highlights

Measurement of maximal inspiratory (MIP) and maximal expiratory (MEP) pressures is an easy, non-invasive, and rapid test to assess the strength of the respiratory muscles (American Thoracic Society/European Respiratory Society, 2002; Caruso et al, 2015)
The standard MIP/MEP test is aimed at non-invasively and selectively assessing the strength of inspiratory and expiratory muscles. Correct performance of this technique requires following the indications published by medical societies, such as the American Thoracic Society (ATS) and the European Respiratory Society (ERS) that agreed to establish a standard protocol, which was published in 2002 (American Thoracic Society/European Respiratory Society, 2002) and was updated by the ERS in 2019 (Laveneziana et al, 2019)
MIP/MEP measurements are obtained in the seated position of patient

Summary

Introduction

Measurement of maximal inspiratory (MIP) and maximal expiratory (MEP) pressures is an easy, non-invasive, and rapid test to assess the strength of the respiratory muscles (American Thoracic Society/European Respiratory Society, 2002; Caruso et al, 2015). MIP is the maximum negative pressure that can be generated by forced inspiration. It is generated by maximum contraction of the diaphragm and intercostal muscles which tend to increase the volume of the rib cage and lung volume. MEP is the maximum positive pressure that can be generated on forced expiration when the abdominal muscles push the diaphragm and the internal intercostals up, tending to reduce the thorax and lung volumes. This test of breathing muscles is a routine procedure in the diagnosis of certain pulmonary diseases, in patients with suspected respiratory muscle weakness. Some examples of very prevalent diseases which alter MIP/MEP values are chronic obstructive pulmonary disease (COPD), neuromuscular diseases, such as multiple sclerosis, or chronic heart failure (Laghi and Tobin, 2003; Kelley and Ferreira, 2017; Nambiar et al, 2018; Laveneziana et al, 2019)

Objectives

Methods

Results

Conclusion