Abstract
Respiratory muscle involvement in ALS leads to nocturnal hypoventilation, which precedes daytime hypercapnia. Sleep apnea syndrome (SAS) may also occur frequently. The relevance of nocturnal TcCO2 (Tosca 500® device) was evaluated prospectively in 40 ALS patients (59 ± 10 ans) with mild to moderate respiratory involvement (FVC ›] 70 % pred). Initiation of NIV in the following 6 months was the main outcome, which occurred in 13 patients. Initial assessment also included a polysomnography and lung function testing. The main criteria for NIV initiation was hypoventilation in 6 cases, a significant SAS (mosty obstructive) in 5, clinical criteria or inspiratory muscle weakness in 2. None of TcPCO2 parameters appeared predictive for the need of NIV. Conversely diurnal HCO3- (26,9 ± 3,3 vs 24,8 ± 1,2 mmol/L; p = 0,01) and the percentage of nocturnal time with a SpO2 ‹ 90 % (4,2 ± 13,6 vs 0,5 ± 0,8; p = 0,007) were higher in patients with subsequent NIV. Differences in FVC % pred and apnea-hypopnea index between patients requiring or not requiring NIV were of borderline significance (p = 0,08 and 0,09). TcCO2 at awakening was weakly related to simultaneous PaCO2 (r= 0,36). Diurnal HCO3 - correlated with the percentage of time with a TcCO2 > 50 mmHg (r = 0,61). In conclusion criteria leading to NIV initiation remain variable in ALS, SAS being a major criteria in 38 % of patients. Nocturnal TcCO2 did not appear highly predictive in ALS patients with moderate respiratory involvement.
Study performed with the funding of ANTADIR federation and ARSLA association.
- © 2014 ERS