Effectiveness of assisted and unassisted cough capacity in amyotrophic lateral sclerosis patients

Decreased cough capacity during a respiratory infection is one of the main causes of acute respiratory failure and hospitalisation in amyotrophic lateral sclerosis (ALS). Objective: To determine whether a respiratory measurement could identify the effectiveness of cough capacity in ALS during a respiratory infection. Methods: This was a prospective study of all ALS patients who were treated at a respiratory care unit due to a respiratory infection from 2012 to 2016. The effectiveness of unassisted and assisted coughing was evaluated and respiratory function tests were performed during the acute episode. Results: Forty-eight ALS patients were enrolled, with only four having an effective unassisted cough. The variable which predicted unassisted cough effectiveness was peak cough flow (PCF) (OR 4499.27; 95%CI 3.60-3219086.19; p=0.022) with a cut-off point of 2.77L/s (166L/min). For manually assisted coughing, the predictor of cough effectiveness was manually assisted PCF (cut-off point of 2.82-169L/min) (OR 2198.602; 95% CI 3.750-1351691.42; p=0.019). Mechanically assisted PCF (cut-off point of 2.95-177L/min) was found to be the predictor of mechanically assisted coughing effectiveness (OR 23.40; 95% CI 2.11-258.96; p=0.010). Conclusions: During a respiratory infection in ALS patients, the effectiveness of assisted and unassisted cough capacity depends on the PCF generated.