The Importance of Positive Expiratory Pressure Associated With the In-exsufflator in ALS Patients

Overview

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder that impairs motor neurons, with a life expectancy of 2 to 7 years after diagnosis. ALS manifests as 'spinal' when it primarily affects limbs, or 'bulbar' when it impairs speech and swallowing. The disease progressively weakens all skeletal muscles, causing respiratory issues and increased risk of lung infections due to ineffective coughing. Mechanical cough assistance via In-exsufflation therapy/ mechanical in-exsufflator devie (INEX/MI-E) applies positive and negative airway pressures non-invasively to improve coughing. However, MI-E may fail in some ALS patients due to airway collapse, often related to brainstem muscle dysfunction.Research by Andersen et al. in 2017 highlighted that during MI-E, ALS patients often experience adverse laryngeal movements, which can obstruct airways and reduce the therapy's effectiveness. To combat this, they suggested individualized MI-E settings to minimize airway collapse. Modern MI-E devices, such as the EOVE-70, offer adjustable positive expiratory pressure (PEP) between cycles to potentially enhance airway stability and coughing efficiency. The current study focuses on the impact of PEP during therapy pauses on the peak expiratory flow rate in ALS patients, which could lead to improved therapeutic outcomes.

Amyotrophic Lateral Sclerosis (ALS) is an incurable and debilitating neurodegenerative disease affecting both upper and lower motor neurons. The average life expectancy upon diagnosis ranges from 2 to 7 years. Treatment is symptomatic, aiming to manage symptoms rather than cure the disease. ALS can be classified as 'spinal' when symptoms primarily affect the limbs or 'bulbar' when the disease manifests with speech, swallowing, or coughing difficulties. Regardless of the subtype, ALS eventually affects all skeletal muscles, including respiratory muscles, leading to impaired coughing efficiency, secretion buildup, and increased lung infections. Enhancing cough efficiency is crucial for clearing airway secretions and reducing pneumonia risk. In healthy individuals, coughing involves an increase in lung volume by inspiratory muscles, coordination of the glottis by laryngeal muscles, and increased thoracoabdominal pressure by expiratory muscles. This process is disrupted in ALS patients. In-exsufflation therapy is widely used and recommended to assist coughing mechanically by applying non-invasive positive and negative pressure changes through a mask. For MI-E to be effective and keep the upper airways open during therapy, coordinated glottic movements are essential. The ultimate goal is to increase peak expiratory flow (PEF) during coughing. However, in some patients, MI-E is ineffective due to the collapse of the upper airways during both phases of the therapy-insufflation and exsufflation-but especially during inspiration, possibly due to dysfunction of the muscles innervated by the brainstem. In 2017, Andersen et al. demonstrated via laryngoscopies conducted during MI-E use that the therapy was associated with: Adduction of the supraglottic laryngeal structures during the insufflation phase. Retraction of the tongue base into the hypopharynx during insufflation. Adduction of the vocal cords in ALS patients during both insufflation and exsufflation, regardless of subtype. These factors compromised the therapy's effectiveness, which aims to increase PEF during cough Andersen et al. concluded that it is important to personalize and adjust the MI-E settings to reduce the risk of airway collapse and allow the maximum number of ALS patients to benefit from it. Today, several MI-E devices are available on the market, sharing similar settings for target pressure (positive/negative), inspiratory/expiratory time, automation, etc. Notably, one particular device (EOVE-70, Eove, Pau) offers the use and adjustment of a positive expiratory pressure (PEP) during the pause (i.e., between each delivered cycle), which could reduce the risk of airway collapse during therapy, and improve cough expiratory flow rate as well as the tolerance and effectiveness of the treatment in ALS patients. The aim of this study is to evaluate the effect of using the positive expiratory pressure function during the pause and before the following insufflation on the peak expiratory flow rate of cough in patients with ALS during MI-E therapy