The multidimensional nature of dyspnoea in amyotrophic lateral sclerosis patients with chronic respiratory failure: Air hunger, anxiety and fear

Background: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder leading to chronic respiratory failure. Few studies have investigated ALS-related dyspnoea, and none have characterised the emotional distress it inflicts. We hypothesised that ALS-related dyspnoea has a strong affective component that relates to quality of life. Methods: This prospective, observational study was conducted in 41 ALS patients > 18 with chronic respiratory failure and an indication for noninvasive ventilation (NIV). Dyspnoea was assessed using the Multidimensional Dyspnea Profile (MDP) at baseline and 1 month after NIV initiation. Correlations between scores evaluating the sensory and affective dimensions of dyspnoea and other patient-reported outcomes and pulmonary function tests were analysed. Results: Dyspnoea was described as intense (median [IQR] score on a 0-10 scale: 6.5 [4.0-7.5]). The sensory dimension of dyspnoea was polymorphic, but "air hunger" was the most common (48.8%) and the most intense (6 [4-8]) sensory descriptor. In the affective domain, most patients rated "anxious" (85.4%) and "afraid" (60.9%) above 0. The MDP affective dimension correlated significantly with other patient-reported outcomes, with the strongest correlation being between MDP "anxious" and the anxiety component of the Hospital Anxiety Depression Scale (Pearson's R = 0.70). One month after initiation of NIV, dyspnoea during unassisted breathing was described in virtually the same terms, particularly the affective dimension. Discussion: ALS-related dyspnoea is intense and fear-provoking, persists during unassisted breathing between NIV sessions, and significantly impacts health-related quality of life. This study highlights the need for increased awareness of and research into ALS-related dyspnoea.