PREDICTION OF NOCTURNAL VENTILATION BY PULMONARY FUNCTION TESTING IN PATIENTS WITH AMYOTROPHIC LATERAL SCLEROSIS

Abstract

TYPE: Late Breaking Abstract TOPIC: Sleep Disorders PURPOSE: In amyotrophic lateral sclerosis (ALS) prognosis is limited by a progressive insufficiency of respiratory muscles. Survival and QOL may be improved by noninvasive ventilation (NIV), which is initially applied during the nighttime. The indication for NIV is based on pulmonary function testing (PFT) and polysomography (PSG) with capnography (tCO2). It is still open, which awake PFT parameters are predictable for nocturnal ventilation. METHODS: We analyzed PFT including spirometry, body plethysmography, DLCO, respiratory muscle testing and blood gas analysis, PSG and tCO2 in 42 patients with ALS (27 men, 15 women, age 69 ± 12,1 y) retrospectively and performed Spearman`s correlation of daytime awake parameters with parameters during sleep. RESULTS: 25 Patients (64%) showed restrictive impairment of ventilation and 15 (48,3%) insufficiency of respiratory musculature (P01/Pimax = 5,6 ± 3,3%; Pimax 40,5 ± 15,4 %Pred; Pemax 56,6 ± 26,9%Pred). We observed strong correlations between daytime inspiratory parameters, as well as DLCO, and FEV1/FVC even in the absence of obstructive impairment of ventilation with nocturnal hypercapnia. Furthermore, awake hypercapnia and concentrations of bicarbonate and base excess were positively correlated with nocturnal hypercapnia. CONCLUSIONS: The prediction of nocturnal ventilation by PFT is limited. Inspiratory parameters performed better than others. This confirms the relevance of inspiratory muscle weakness in ALS. CLINICAL IMPLICATIONS: PFT in ALS should focus on inspiratory parameters. PSG and tCO2 remain the gold standard for the assessment of nocturnal ventilation. DISCLOSURE: No significant relationships. KEYWORD: Amyotrophic lateral sclerosis