Waveforms Analysis in Patients With Amyotrophic Lateral Sclerosis for Enhanced Efficacy of Mechanically Assisted Coughing

Abstract

Background: Effectiveness of mechanical assisted coughing with insufflation-exsufflation (MI-E) in amyotrophic lateral sclerosis (ALS) depends largely on severity of bulbar dysfunction, which can generate different upper-airway responses. The aim of the study was to evaluate the use of graphs generated by MI-E in ALS to detect airway obstruction and set parameters to achieve an effective mechanically assisted coughing.

Methods: This was a prospective study enrolling patients with ALS. Several sessions with MI-E were applied, administering different insufflation-exsufflation (± 20, ± 30, ± 40, ± 50 cm H₂O) levels in each session. The graphs produced were recorded and analyzed, and the results were used to select the parameters resulting in more effective MI-E.

Results: Sixty-nine subjects with ALS were included, yielding a total of 351 analyzed records. A pattern of obstruction during insufflation was detected in 34 subjects (50.7%) and of upper-airway collapse during exsufflation in 18 subjects (26%). The variable associated with obstruction during insufflation was bulbar upper motor neuron dysfunction (odds ratio 7.19 [95% CI 2.32-22.29], P = .001), whereas bulbar lower motor neuron dysfunction was related to upper-airway collapse during exsufflation (odds ratio 0.32 [95% CI 0.11-0.98], P = .046). After parameters were adjusted, in 68 subjects (98.55%) an effective MI-E was achieved. The only variable that predicted absence of alterations in the graphs was Norris bulbar score (odds ratio 0.87 [95% CI 0.78-0.96], P = .007).

Conclusions: Analysis of graphics generated by applying MI-E in ALS was an effective method to detect upper-airway responses and select optimal set parameters. Obstruction during insufflation is related to bulbar upper motor neuron dysfunction and collapse during exsufflation to bulbar lower motor neuron dysfunction.

Keywords: amyotrophic lateral sclerosis; cough assist; mechanical in-exsufflation; upper airwave.