Non-invasive ventilation and hypercapnia-associated symptoms in amyotrophic lateral sclerosis

During the course of amyotrophic lateral sclerosis (ALS), progressive weakness of respiratory muscles leads to chronic hypercapnia which causes various symptoms like sleep disturbances, daytime fatigue, and depression. Non-invasive ventilation (NIV) improves survival and quality of life, but little is known about its effect on these specific symptoms, in particular during the later course of disease. Our aim was to evaluate the short- and long-term effects of NIV on hypercapnia-associated symptoms in ALS.

We prospectively analyzed sleep disturbance, daytime fatigue, and depression using standardized scales (Pittsburgh sleep quality index [PSQI], stanford sleepiness scale [SSS], Beck depression inventory [BDI], and Clinical hypoventilation score [CHS]) in 58 patients with NIV. Follow-up was done every 3 months up to a maximum of 24 months.

We found significant improvements of all outcome parameters except BDI within the first three months after NIV initiation. The median PSQI improved from 6.5 (95% CI: 5.0-8.5) to 6.0 (95% CI: 4.5-7.0; P = 0.042), the SSS from 3.0 (95% CI: 2.0-4.0) to 2.0 (95% CI: 2.0-3.0; P = 0.004), and the CHS from 22.0 (95% CI: 19.5-25.0) to 18.0 points (95% CI: 12.0-23.5; P = 0.013). Patients with bulbar and spinal onset were not significantly different, and positive effects were long-lasting.

Our data show that NIV improves hypercapnia-associated symptoms within the first 3 months after initiation in spinal as well as bulbar patients, and that beneficial effects are long-lasting.