Noninvasive Ventilation Effectiveness in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons; respiratory problems are the leading cause of death and hospital admissions and are secondary to progressive weakness of the respiratory muscles and upper airway. Noninvasive ventilation (NIV) can increase survival, alleviate symptoms, reduce hospital admissions, and improve the quality of life of these patients. The key factor in respiratory management of patients with ALS is achieving effective NIV; ineffective NIV has a negative impact on survival, with a reduction of up to 50% compared to patients with an effective technique. The most common cause of ineffective NIV is air leaks; other causes include upper airway obstruction events, residual hypoventilation, hyperventilation, and upper airway obstruction secondary to an oronasal mask. Regular monitoring of the effectiveness of NIV is essential given its impact on survival; the key tools that detect the main problems are the presence of hypoventilation symptoms, arterial blood gases, nocturnal oximetry and capnography, and built-in ventilator software. Different measures have been proposed to address the ineffectiveness of NIV, such as fitting the mask to reduce air leaks, increasing ventilatory support for residual hypoventilation, decreasing ventilatory support for hyperventilation, or a trial with a nasal mask to address oronasal interface effects. In the case of obstruction, the most common measure is to increase positive expiratory pressure during NIV. These measures enable NIV to be effective in 58% of cases, achieving a survival rate similar to that of patients who have effective NIV from the outset.