Effect of Noninvasive Ventilation on Lung Function in Amyotrophic Lateral Sclerosis

Effect of Noninvasive Positive Pressure Ventilation on Pulmonary Function Testing 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.

"BiPAP" (Respironics), variable positive airway pressure (VPAP) (ResMed), bilevel positive airway pressure, noninvasive ventilation

Each subject will undergo 2 hours of high-level noninvasive positive pressure ventilation, with an inspiratory positive airway pressure of 12 cm H2O and an expiratory positive airway pressure of 3 cm H2O.

Each subject will undergo 2 hours of low-level noninvasive positive pressure ventilation, with an inspiratory positive airway pressure of 6 cm H2O and an expiratory positive airway pressure of 3 cm H2O.

Inclusion Criteria: clinical diagnosis of amyotrophic lateral sclerosis clinical indication to start noninvasive ventilation (forced vital capacity < 50% predicted or signs/symptoms of respiratory insufficiency) age 18 to 80 years old Exclusion Criteria: prior institution of NIPPV inability to safely use NIPPV indications for tracheostomy assisted ventilation because of inability to clear secretions from the airway inability or unwillingness to perform pulmonary function testing presence of advanced dementia.