Effect of Noninvasive Ventilation on Lung Function in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS), or "Lou Gehrig's Disease", is a fatal disorder that causes progressive degeneration and weakening of the muscles of breathing, leading to breathing insufficiency and eventually breathing failure. This breathing insufficiency is commonly treated with a breathing assistance device, known as noninvasive positive pressure ventilation (NIPPV). While generally well tolerated and accepted, it is not clear whether or to what extent NIPPV in fact helps breathing function: some data suggest that NIPPV preserves breathing function over time, whereas other data suggest that it actually causes breathing function to decline more quickly. No studies have shown what the acute effect of NIPPV is on breathing muscle function in ALS patients. This study will test the hypothesis that the acute use of NIPPV, at pressure levels that are in common clinical use, will cause measurable changes in tests of breathing function, compared to baseline and to lower levels of NIPPV. We expect that the results of this study will help to clarify whether and to what extent NIPPV assists respiratory muscle function in patients with ALS.