A comparison of assisted cough techniques in stable patients with severe respiratory insufficiency due to amyotrophic lateral sclerosis

Cough can be impaired in ALS. This can result in peak cough flows (PCFs) too low for an adequate airway clearance (<270 l/mn). There are several cough assistance techniques that aim at a better elimination of airway secretions, but which are effective, especially in bulbar patients, is not known. We designed the present investigation to compare the PCFs produced by a range of manual and mechanical techniques in patients with ALS, in non-bulbar but also in bulbar patients. In the whole study population, PCFs ranged from 84 (35–118) l/mn for the spontaneous cough manoeuvre to 488 (243–605) l/min for the in/exsufflator (p = 0.0005). In the bulbar group, these values were 42 (35–130) l/min versus 436 (244–630) l/min, respectively (p = 0.008), and 89 (40–106) l/min versus 491 (192–580) l/min, respectively, in the non-bulbar group (p = 0.019). There was no statistically significant difference between the bulbar and the non-bulbar groups. The in/exsufflator was not always the best tool. We conclude that capacity of coughing efforts to produce efficient peak cough flows can be dramatically improved with different tools, even in patients with very severe bulbar symptoms and that it appears useful to test an array of techniques to optimally tailor cough improvement techniques to individual patients.