Titration of Mechanical Insufflation-Exsufflation Optimal Pressure Combinations in Neuromuscular Diseases by Flow/Pressure Waveform Analysis.

Introduction: The aim of this study was to assess several air-pressure settings for MI-E to determine their effect on peak cough flow (PCF), and to compare the best pressures with those are more common used in the literature (±40cmHO) in patients with neuromuscular disorders (NMD).

Methods: Adults with NMD in whom MI-E was indicated were recruited. Assisted PCF was measured by an external pneumotachograph. The protocol included 9 PCF measures per patient: 1 baseline (non-assisted), 4 with increasing inspiratory pressures without negative pressure (10, 20, 30 and 40cmHO or maximum tolerated), and then 4 adding expiratory pressures (-10, -20, -30 and -40cmHO or maximum tolerated) with maximum inspiratory pressure previously achieved.

Results: Twenty one patients were included, 61% with amyotrophic lateral sclerosis (ALS). Mean PCFs with recommended pressures (±40cmHO) were lower than the scored in the individualized steps of the titration protocol (197.7±67l/min vs 214.2±60l/min, p<0.05). Regarding subgroups, mean PCF values in ALS patients with bulbar symptoms were significantly higher than those achieved with recommended pressures (163.6±80 vs 189±66l/min, p<0.05).

Conclusion: The PCF obtained with the protocol did not always match the recommended settings. It may be advisable to perform MI-E titration assessed by non-invasive PCF monitoring in patients with NMD, especially in ALS with bulbar involvement to improve the therapy detecting airway collapse induced by high pressures.