Efeitos Fisiológicos da Ventilação por Peça Bucal, Recrutamento do Volume Pulmonar e Tosse Mecanicamente Assistida Medidos pela Tomografia de Impedância Elétrica em Pacientes Neuromusculares com Insuficiência Respiratória Severa.

Abstract

Introduction: Patients with Neuromuscular Diseases (NMD) have respiratory muscle weakness and develop respiratory failure, which is the leading cause of death in this population. To achieve respiratory stability, these patients require noninvasive ventilatory support during sleep, which can be extended to 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 physiological differences in respiratory parameters and ventilatory variables during Spontaneous Breathing (SB), during daytime ventilatory support by MPV, when using the LVR maneuver and during the use of the MI-E. Methods: Adult patients diagnosed with NMD, with severe ventilatory dependence (dependent on noninvasive ventilatory support 24 hours a day) were monitored by EIT at four different times: In SB, during daytime ventilatory support with MPV, when performing LVR and during MI-E. Demographic data, respiratory rate (RR), peripheral oxygen saturation (SpO2) transcutaneous Pressure of Carbon Dioxide (PtcCO₂), impedance ventilation variation (TVz), TVz at two different times (Delta TVz), and End-Expiratory Lung Volume variation (EELz) were analyzed during all ventilatory strategies. Results: In this physiological study, four male neuromuscular 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 noninvasive ventilatory support 24 hours a day, using a mask at night and a mouthpiece (MPV) during the day with a median assisted tidal volume (Vt) of 1325 (1150-1388) mL. All patients performed LVR and use MI-E maneuvers daily at home, with pressures of +50 and -50 cmH2O. Through EIT, it was possible to evaluate TVz values in SB: 9.1 (7.5-77) ua, MPV: 47.6 (28-94) ua, LVR: 75 (37.9-108) ua, and MI-E: 157.5 (91.1-176.5) ua. In all patients analyzed, significant differences in TVz values were observed when comparing SB vs. LVR (p<0.05), SB vs. MI-E (p=0.001), and MVP vs. IE-M (p<0.05). The Delta TVz values between SB and MPV were 317 (60-422) %, between SB and LVR were 447 (96-783) %, between SB and MI-E was 1183 (233-2133) %, between MPV and LVR was 34 (10-73) %, between MPV and MI-E was 164 (81-564) %, and between LVR and MI-E was 56 (32-353) %. The values of the variation of EELz between SB vs. MPV were 6.9850 (3.7850-12.9375) ua, between SB vs. LVR 7.995 (4.845-23.393) ua, between SB vs. MI-E 9.5600 (-23.6675-28.3350) ua, between MPV vs LVR of 7.5150 (0.5775-27.0300) ua, between MPV vs. MI-E of 10 (-40.4250 - 20.1400) ua and between LVR vs. MI-E of 19.3400 (-41.6500-3.9825). No significant differences were found in respiratory rate, peripheral oxygen saturation, and PtcCO2 values in the ventilatory strategies applied. Conclusion: This physiological study with EIT monitoring allowed us to observe different values of TVz and EELz according to different ventilatory strategies. The Delta TVz between SB and MPV moments confirms effective daytime ventilatory support. MI-E was the strategy that produced the highest Delta TVz and EELz variation when compared to LVR for lung expansion.