Noninvasive ventilation in ALS

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Abstract
Background: Noninvasive ventilation (NIV) probably improves survival in ALS, but the magnitude and duration of any improvement in quality of life (QoL) and the optimal criteria for initiating treatment are unclear. Methods: QoL (Short Form-36 [SF-36], Chronic Respiratory Disease Questionnaire, Sleep Apnea Quality of Life Index) and respiratory function were assessed every 2 months and polysomnography every 4 months in 22 subjects with ALS. A trial of NIV was offered when subjects met one or more predefined criteria: orthopnea, daytime sleepiness, unrefreshing sleep, daytime hypercapnia, nocturnal desaturation, or an apnea–hypopnea index (AHI) of >10. Seventeen subjects were offered a trial of NIV; 15 accepted, and 10 continued treatment subsequently. Outcome was assessed by changes in QoL and NIV compliance (h/day). Subjects were followed to death or for at least 26 months. Results: QoL domains assessing sleep-related problems and mental health improved (effect sizes 0.88 to 1.77, p < 0.05) and were maintained for 252 to 458 days. Median survival following successful initiation of NIV was 512 days, and survival and duration of QoL benefit were strongly related to NIV compliance. Vital capacity declined more slowly following initiation of NIV. Orthopnea was the best predictor of benefit from, and compliance with, NIV. Daytime hypercapnia and nocturnal desaturation also predicted benefit but were less sensitive. Sleep-related symptoms were less specific, and AHI > 10 was unhelpful. Moderate or severe bulbar weakness was associated with lower compliance and less improvement in QoL. Conclusions: NIV use was associated with improved QoL and survival. Subjects with orthopnea and preserved bulbar function showed the largest benefit.