Initiation of noninvasive ventilation in patients with amyotrophic lateral sclerosis.

Introduction/aims: Noninvasive ventilation (NIV) has been shown to improve survival and symptom burden in patients with amyotrophic lateral sclerosis (ALS). However, limited data exist regarding the clinical and physiological parameters at the time of NIV initiation. This study aimed to describe the clinical characteristics and respiratory physiological markers in a cohort of ALS patients with chronic respiratory failure.

Methods: This is a single-center retrospective cohort study of patients with ALS assessed for NIV initiation between February 2012 and January 2021. NIV was initiated based on insurance eligibility criteria: daytime hypercapnia, defined by partial pressure of carbon dioxide (PaCO₂) >45 mm Hg using diurnal transcutaneous CO₂ (TcCO₂) as a surrogate, a maximal inspiratory pressure (MIP) <60 cmH₂O or forced vital capacity (FVC) <50% predicted normal.

Results: We identified 335 patients with ALS and chronic respiratory failure referred to an outpatient home ventilation clinic for NIV initiation. The mean age was 64 years ±11; 151 (45%) were female, 326 (97%) were white, and 100 (29%) had bulbar-onset ALS. At the time of NIV initiation, the mean FVC was 64% ± 19%, the mean MIP; 41 cmH₂O ± 17, and diurnal TcCO₂; 40 ± 6 mmHg. The most common reasons for NIV initiation were MIP <60 cmH₂O (58%) and multiple concomitant indications (28%). Within 1 year of NIV initiation, 126 (37%) patients were deceased.

Discussion: We found that impairment in inspiratory force was the most common reason for NIV initiation and often preceded significant declines in FVC.