Sleep apnea in adult myotonic dystrophy patients who have no excessive daytime sleepiness.
ABSTRACT Sleep apnea is common in myotonic dystrophy (MD) and may cause respiratory failure. Most of the sleep studies have been performed in patients with excessive daytime sleepiness (EDS), which is a characteristic and strong predictor of sleep apnea. Therefore, we investigated the prevalence of sleep apnea in adult MD patients who have no EDS.
Epworth Sleepiness Scale was used to exclude EDS and a score over 10 was accepted as an indicator of EDS. Sleep studies of 17 adult MD patients with the Epworth sleepiness scale score < or =10 were retrospectively reviewed. Spirometry (n = 16) and daytime arterial blood gasses were used to evaluate the relationship with nocturnal parameters.
On admission to the outpatient chest clinic, seven patients had normal spirometry, and ten had daytime hypercapnia and/or hypoxemia. All but one had sleep apnea (apnea-hypopnea index > or =5 events/h of sleep; mild in five, moderate in seven, and severe in four). Hypopneas were more common than apneas (16.9 +/- 13.2 events/h vs. 4.6 +/- 4.1 events/h). Nocturnal desaturation episodes were very frequent (oxygen desaturation index, 19.7 +/- 20.3/h of sleep). Three patients had central sleep apnea and 13 had obstructive sleep apnea. Body mass index, spirometry parameters (FVC and FEV1) and arterial oxygen tension were moderately correlated with nocturnal oxygenation parameters. Apnea-hypopnea index showed moderate correlation with spirometry parameters (FVC and FEV1).
Sleep apnea and oxygen desaturations are very common in MD patients who report no excessive daytime sleepiness. Daytime lung function parameters are not sufficiently reliable for screening sleep apnea. Therefore, we recommend routine polysomnography in MD patients.
Article: Hypoventilation syndromes.[Show abstract] [Hide abstract]
ABSTRACT: In patients with impaired inspiratory muscle function or altered respiratory system mechanics, an imbalance between load and capacity can arise. The ventilatory control system normally compensates for this by increasing drive to maintain adequate alveolar ventilation levels, thereby keeping arterial CO2 within its normal range. To reduce work of breathing, a pattern of reduced tidal volume and increased respiratory rate occurs. This pattern itself may eventually reduce effective ventilation by increasing dead space ventilation. However, the impact of sleep on breathing and its role in the development of diurnal respiratory failure is often overlooked in this process. Sleep not only reduces respiratory drive, but also diminishes chemoresponsiveness to hypoxia and hypercapnia creating an environment where significant alterations in oxygenation and CO2 can occur. Acute increases in CO2 load especially during rapid eye movement sleep can initiate the process of bicarbonate retention which further depresses ventilatory responsiveness to CO2. Treatment of hypoventilation needs to be directed toward factors underlying its development. Nocturnal noninvasive positive pressure therapy is the most widely used and reliable strategy currently available to manage hypoventilation syndromes. Although this may not consistently alter respiratory muscle strength or the mechanical properties of the respiratory system, it does appear to reset chemosensitivity by reducing bicarbonate, resulting in a more appropriate ventilatory response to CO2 during wakefulness. Not only is diurnal hypoventilation reduced with noninvasive ventilation, but quality of life, functional capacity and survival are also improved. However, close attention to how therapy is set up and used are key factors in achieving clinical benefits. © 2014 American Physiological Society. Compr Physiol 4: 1639-1676, 2014.
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ABSTRACT: Restrictive lung disease leads to ventilatory defects and diffusion impairments. These changes may contribute to abnormal nocturnal pathophysiology, including sleep architecture disruption and impaired ventilation and oxygenation. Patients with restrictive lung disease may suffer significant daytime fatigue and dysfunction. Hypercarbia and hypoxemia during sleep may impact progression of lung disease and related symptoms. Little is known about the impact of treatment of sleep disruption on sleep quality and overall prognosis in restrictive lung disease. This review discusses the pathophysiology of sleep and comorbid sleep disorders in restrictive lung diseases including interstitial lung disease, neuromuscular disease, and obesity hypoventilation syndrome.Clinics in Chest Medicine 09/2014; DOI:10.1016/j.ccm.2014.06.006 · 2.17 Impact Factor
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ABSTRACT: Here we describe a clinical approach and differential diagnosis for chronic muscle diseases which include early respiratory failure as a prominent feature in their presentation (i.e. respiratory failure whilst still ambulant). These patients typically present to neurology or respiratory medicine out-patient clinics and a distinct differential diagnosis of neuromuscular aetiologies should be considered. Amyotrophic lateral sclerosis and myasthenia gravis are the important non-muscle diseases to consider, but once these have been excluded there remains a challenging differential diagnosis of muscle conditions, which will be the focus of this review. The key points in the diagnosis of these disorders are being aware of relevant symptoms, which are initially caused by nocturnal hypoventilation or diaphragmatic weakness; and identifying other features which direct further investigation. Important muscle diseases to identify, because their diagnosis has disease-specific management implications, include adult-onset Pompe disease, inflammatory myopathy, and sporadic adult-onset nemaline myopathy. Cases which are due to metabolic myopathy or muscular dystrophy are important to diagnose because of their implications for genetic counselling. Myopathy from sarcoidosis and colchicine each has a single reported case with this presentation, but should be considered because they are treatable. Disorders which have recently had their genetic aetiologies identified include hereditary myopathy with early respiratory failure (due to TTN mutations), the FHL1-related syndromes, and myofibrillar myopathy due to BAG3 mutation. Recently described syndromes include oculopharyngodistal muscular dystrophy that awaits genetic characterisation.Journal of Neurology 11/2014; DOI:10.1007/s00415-014-7526-1 · 3.84 Impact Factor