Pulmonary functions and sleep-related breathing disorders in lipid storage disease

Pulmonary function abnormalities and sleep-related breathing disorders (SRBD) are frequent in subjects with several neuromuscular diseases but there is no data about lipid storage diseases (LSD). Therefore, we aimed to evaluate pulmonary functions and SRBD in adults with LSD.

Pulmonary functions (forced expiratory volume (FEV₁), forced vital capacity (FVC), supine FVC, upright-supine FVC% change, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), peak cough flow (PCF)), arterial blood gases, and polysomnographic data of all subjects were evaluated.

Twenty-five subjects with LSD were evaluated [17 males, 8 females; age 34.9 ± 15 years; BMI 26.5 ± 3.4 kg/m²]. MIP was - 72.2 ± 32.7 cmH₂O (< - 80 cmH₂O in 13 subjects), MEP was 80.9 ± 39.1 cmH₂O (< 80 cmH₂O in 9 subjects, < 40 cmH₂O in 6 subjects), and PCF was 441.3 ± 190.9 L/min (< 360 L/min in 11 subjects). FVC was 87.8% ± 25.7 and 6 subjects had FVC < 80%. Seven subjects had diaphragm dysfunction (four upright-supine FVC% ≥ 15, three dyspnea in supine position with paradoxical abdominal respiration). Five subjects had hypoxemia (PaO₂ < 80 mmHg) and 8 subjects had hypercapnia (PaCO₂ > 45 mmHg). REM sleep had decreased in all subjects (10.2% ± 6.1). Obstructive sleep apnea (OSA) was found in 80% of the subjects (n = 20; 9 mild, 9 moderate, 2 severe). For subjects with OSA, apnea-hypopnea index (AHI) was 20.8 ± 15.9/h, oxygen desaturation index (ODI) was 11.9 ± 15.4/h, AHI_REM was 30.6 ± 19.7/h, AHI_NREM was 19.7 ± 16.6/h, ODI_REM was 27.2 ± 26.1/h, and ODI_NREM was 11.4 ± 15/h. Five subjects (20%) diagnosed as REM-related OSA. Nocturnal mean SpO₂ was 94.9% ± 1.7, lowest SpO₂ was 73.3% ± 13.9, and time spent with SpO₂ < 90% was 2.4% ± 7.2.

In subjects with LSD, pulmonary function impairment, daytime hypercapnia and hypoxemia, and OSA, especially REM-related OSA, are frequent. Therefore, pulmonary functions and polysomnography should be performed routinely.