• R Ragette, U Mellies, C Schwake, and H Teschler.
• Ruhrlandklinik, Abteilung Pneumologie/Schlaf- und Beatmungsmedizin, Essen. regine.ragette@uni-essen.de
• Pneumologie. 2003 Dec 1;57(12):729-33.

UnlabelledSleep-disordered breathing is common in neuromuscular diseases but remains poorly defined in its relationship to daytime respiratory function.MethodsWe prospectively compared supine lung and respiratory muscle function with results of polysomnography/capnometry in 35 patients with progressive myopathies (age 32.5 +/- 15 years).Results32/35 patients had restrictive ventilatory defect, 9/32 had hypercapnic respiratory failure by day (PaCO(2) 66.0 +/- 15.7 mm Hg). Supine inspiratory vital capacity (IVC(S)) correlated with maximal inspiratory muscle pressure (R = 0.75), respiratory muscle strain (P0.1/PImax, R = - 0.68), and daytime blood gases (p < 0.005 for all). SDB in the way of REM-sleep hypopneas, circumscribed hypoventilation episodes and sleep-stage independent continuous hypoventilation (PtcCO(2) > 50 mmHg > 50% of sleep time) was common at IVC(S)< 60% pred, and preceded daytime hypercapnia. IVC(S) correlated with nocturnal SaO(2) (R = 0.64), PtcCO(2) (R = - 0.87), percent light sleep (R = 0.67) and deep sleep (R = - 0.76). IVC(S) correlated only marginally with respiratory disturbance index (total sleep, R = - 0.45; REM-sleep, R = - 0.44). IVC(S) < 60% was 96% sensitive, 78% specific for presence of SDB. IVC(S) < 20 % was 89% sensitive, 96% specific for daytime hypercapnia.ConclusionsIVC(S) correlates with respiratory muscle function, daytime and nocturnal blood gases, and is highly predictive of SDB and daytime hypercapnia.

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