Respiratory failure has been described in myotonic dystrophy; it worsens during sleep but its central or peripheral origin has yet to be determined. Moreover, patients may present severely disturbed sleep and daytime somnolence. Eight patients with mild to moderate myotonic dystrophy were studied to assess breathing function while awake and during sleep by means of the pulmonary function tests, nocturnal polysomnographic examination and the multiple sleep latency test (MSLT). Three patients had restrictive respiratory defects; none had signs of airway obstruction. All patients had very disrupted nocturnal sleep. Of six patients who underwent the MSLT only two showed a mild tendency to sleep during the day. Six patients had pathological apnoea plus hypopnoea index [(A+H)I] and there was a prevalence of central apnoeas. The apnoeas occurred while resting but awake and throughout all sleep stages. Only two patients (the ones with the least vital capacity) had episodes of progressive oxygen desaturation during rapid eye movement sleep, similar to those found in other restrictive disorders and in chronic obstructive pulmonary disease. It is concluded that the breathing pattern characteristic of our myotonic dystrophy patients was the occurrence of central apnoeas both at rest while awake and during sleep.

Background: Exertional dyspnea and exercise incapacity are the most prominent and disabling symptoms and the main contributors to health-related quality of life in patients with idiopathic pulmonary fibrosis (IPF). Objectives: There are no comprehensive studies on pulmonary function tests (PFTs), dyspnea, exercise capacity and radiographic scores in IPF. We therefore sought to investigate the functional variables that can predict dyspnea, exercise capacity and disease extent in IPF. Methods: Thirty-four patients with IPF according to the ATS/ERS criteria underwent PFTs, Medical Research Council (MRC) dyspnea scoring, 6-min walking distance (6-MWD) and radiographic evaluation of fibrosis (HRCT score). Results: The 6-MWD (% pred.) was more impaired than PFTs. Residual volume (RV) showed the best correlation with the extent of fibrosis (r = –0.67, p = 0.0001) and, together with the alveolar-arterial gradient for O₂ [ΔP(A – a)O₂], was an independent predictor of disease extent (R² = 0.44). PFTs showed significant though weak correlations with MRC score and 6-MWD. According to the regression analysis, DL_CO and the HRCT fibrosis score were independent predictors of dyspnea, though they explained only 28% of the overall variance. FEV₁ and ΔP(A – a)O₂ were independent predictors of 6-MWD (R² = 0.31). Conclusions: PFTs and lung volumes in particular are closely related to the HRCT score, a measure of the extent of IPF. The correlation of dyspnea score and 6-MWD to PFTs is limited, due to the complexity of mechanisms leading to exercise limitation in IPF. Therefore dyspnea and exercise performance are largely independent indices and should be followed together with PFTs and HRCT score in order to better assess the status and progress of IPF patients.

No abstract

This article indicates that occurrence of LAM may be possible in a chromosomally normal man unaffected by TSC. On diagnostic grounds, the possibility of LAM should be borne in mind when diffuse cystic lung disease occurs in a man, even in the absence of signs of TSC.