14 research outputs found

    Sleep hypoxia in myotonic dystrophy and its correlation with awake respiratory function.

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    BACKGROUND--Tiredness and daytime respiratory failure occur frequently in myotonic dystrophy. Sleep hypoxaemia was studied in 12 patients with myotonic dystrophy and correlations were sought with their daytime lung and respiratory muscle function. METHODS--All patients underwent overnight sleep studies, clinical assessment, measurement of flow-volume loops and carbon monoxide transfer factor, arterial blood gas analysis, and physiological assessment of both thoracic muscle function and upper airways obstruction. RESULTS--The mean nadir of oxygen saturation during sleep was 75% (95% confidence interval 69% to 81%). A mean of 3.4% of total sleep duration was spent at an oxygen saturation level below 85%. Five of the 12 patients had an apnoea index of > 5, the group mean apnoea/hypopnoea index being 15.8 events/sleep hour. The mean awake arterial oxygen tension (PaO2) was 10.7 kPa. There was a trend to hypercapnoea with a mean awake arterial carbon dioxide tension of 6.1 kPa; carbon dioxide retention worsened during sleep. Respiratory muscle dysfunction was mainly evident as a low maximum expiratory mouth pressure. Upper airway obstruction assessed by physiological criteria was found in four of the 12 patients. The proportion of total sleep duration with oxygen saturation levels below 85% was directly related to body mass index (weight/height2) and inversely related to the awake PaO2. Body mass index was inversely related to the overnight nadir of oxygen saturation. CONCLUSIONS--Patients with myotonic dystrophy are often hypoxic during sleep and the subgroup that are obese, or have symptoms of sleep apnoea, or both, are particularly at risk. Sleep studies should be considered in this subgroup of patients with myotonic dystrophy

    Surface characterization of chemically modified wool

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    The surface topography of wool fiber, and in particular the scale height and surface roughness, has been characterized using three-dimensional scanning electron microscopy (3D-SEM). The analysis methodology allows the scale height and surface roughness to be accurately and quickly measured, and may provide detailed information about the fiber topography, any associated damage and possible surface coatings. The treatment of wool fiber with potassium permanganate in salt solution was assessed using 3D-SEM and the progressive reduction in the scale height and cuticle smoothing demonstrated. While this effect was relatively obvious and uniform, the effect of a proteolytic enzymatic treatment on the fiber surface was less uniform. The associated effect of the enzymatic modification on the felting shrinkage, fabric strength, and handle was also determined
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