Physiologic Effects of Mouthpiece Ventilation, Lung Volume Recruitment and Mechanical Assisted Coughing Measured by Electrical Impedance Tomography in Neuromuscular Patients With Severe Respiratory Failure.

Introduction: Patients with Neuromuscular Diseases (NMD) have respiratory muscle weakness and develop chronic respiratory failure. To achieve respiratory stability, these patients require noninvasive ventilatory support (NVS) during sleep and daytime use through mouthpiece ventilation (MPV). Lung volumes can be increased with Lung Volume Recruitment (LVR) and cough effectiveness can be increased with Mechanical Insufflation-Exsufflation (MI-E). Electrical Impedance Tomography (EIT) is a noninvasive, radiation-free monitoring tool that allows real-time measurement of ventilatory parameters, regional lung ventilation, and lung volume variations. This physiological study aims to evaluate, through EIT monitoring, the differences in respiratory parameters and ventilatory variables during Spontaneous Breathing (SB), NVS by MPV, when using LVR and during MI-E. Materials and Methods: Adult patients diagnosed with NMD, were monitored with EIT at four different times: In SB, during MPV, when performing LVR and during MI-E. Demographic data, respiratory rate (RR), peripheral oxygen saturation (SpO2) transcutaneous CO2 (TcCO2), impedance tidal volume (TVz), TVz variation between two different strategies (Delta TVz), and End-Expiratory Lung Volume variation (EELz) were analyzed during all ventilatory strategies. Results: Four male NMD patients were evaluated, with a median age of 24. 5 (19. 8-27. 8) years, Vital Capacity of 450 (362. 5-1212. 5) mL, Peak Cough Flow of 75 (62. 5-260) L/min, and Maximum Insufflation Capacity of 1250 (725-2525) mL, all dependent on NVS 24 hours a day and familiar with LVR and MI-E at home. Median values of TVz, TVz variation and EELz in different ventilatory strategies are described in table 1. No significant differences were found in RR, SpO2 and TcCO2 values during the ventilatory strategies applied. Conclusions: EIT monitoring permits to observe values of TVz variation and EELz in NMD patients. Comparing TVz and EELz variation between SB, MPV, LVR and MI-E may help to choose the best therapeutic options. In this study, MI-E was the strategy that produced the highest TVz and EELz variation. Anexos 2012₀. docx 2012₁. docx