Physiological Study About Advantages of Monitoring Mechanical Assisted Cough

A cross-sectional observational study was performed with patients with NMD who had PFC below 160l/min according to Mechanical insufflation- exsufflation (MI-E ) criteria to assit the cough.

Exclusion criteria were age <18 years, patients who had undergone tracheostomy, exacerbated or with psychiatric problems and patients with relative contraindications (bullous emphysema background, risk of pneumothorax or recent barotrauma).

MI- E study protocol An original protocol was established to perform treatment assessment with Cough Assitst T70 MI-E device® Phillips Respironics. Protocol based on 9 phases of monitoring cough. First was baseline performed for the patient without mechanical assistance and the others were performed by incremental inspiratory and expiratory pressures (cm H2O). Considering ±40 cmH2O as optimal, it was the maximum at the study. An increase of 10 cm H2O in each phase was made starting with the inspiratory pressure (10 to 40 cm H2O or maximum tolerated). Once the maximum pressure tolerated by the patient was reached, the expiratory pressure was introduced following the same sequence. (-10 to -40 cm H2O or maximum tolerated).

Monitoring MI- E protocol: signals and instrumentation As a signal acquisition system, an external polygraph (16Sp Powerlab, ADInstruments, Sydney, Australia), equipped with a pressure transducer (1050 model) and a pneumotachograph (S300, instrumental dead space _ 70 mL, resistance _ 0.0018 cm H2O/L/s) was connected to MI-E device. Sampling frequency was set to 200 Hz, and the polygraph was connected to a personal computer equipped with Chart 7.0 software for Windows.

Signal processing and analysis of waveforms, pressure-time and flow-time, were performed by this software that allowed calculate Peak cough flow maximum in each phase and checking possible respiratory events what could happen during the therapy.