Evaluation of non-invasive ventilatory support in amyotrophic lateral sclerosis using diaphragmatic ultrasound

Abstract

<b>Introduction:</b> Ventilatory insufficiency and respiratory failure are inevitable in patients with amyotrophic lateral sclerosis (ALS), reflecting the progressive paralysis of the inspiratory muscles, primarily of the diaphragm. Non-invasive ventilation (NIV) is used to support respiration and prolong the survival. <b>Aim:</b> To assess diaphragmatic function using diaphragm ultrasound (DUS) before and after NIV initiation in patients with ALS. <b>Materials and methods:</b> Two subjects diagnosed with ALS, according to El Escorial criteria, were included in this pilot study. A forced vital capacity (FVC) &lt; 50% of the predicted value was considered indicative of the need for NIV initiation. During the first visit the subject evaluation included spirometry, DUS and night polysomnography followed by NIV titration. In a 3-month follow-up, spirometry and DUS were repeated. Changes in spirometric values and diaphragm thickness at rest (TdRest), after maximal expiration (TdME) and maximal inspiration (TdMI) were recorded, as well as the ΔTdMI-ME. Diaphragm thickening fraction (TdF) was calculated as TdF (%) = [(TdMI -TdME)/ TdME] x 100. <b>Results:</b> After the 3-month course of NIV, no further deterioration of diaphragmatic function was detected. In the first patient, increase in TdF (35% vs. 51%) and ΔTdMI-ME (0.37 vs. 0.52) was shown, whereas the second patient had no significant changes in TdF (39% vs. 37%) and ΔTdMI-ME (0.79 vs. 0.74). Their spirometric values did not have significant changes as well. <b>Discussion:</b> Our preliminary results suggest that the use of NIV, as indicated in ALS, offers a crucial ventilatory support to the diaphragm, as it is shown in the DUS measurements.