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.
"Impaired sleep disorders are clearly present in both adults and children and can be present as sleep-related breathing events, periodic limb movements or REM-sleep disturbances   . Apnea and hypopnea are common in DM1 and have been described in patients with DM2 even in those without EDS    and these also disturb sleep. "
[Show abstract][Hide abstract] ABSTRACT: We investigate a multiplexing communications system, with many
independent users competing for space in the transmitter buffer. The
control consists in the deletion of selected low priority cells, or
various formally equivalent forms. Under reasonable conditions, such
systems can be approximated by diffusion type processes. This
approximation is the basis of numerical methods for the associated
control problems, which are generally much simpler than what one would
have by working directly with the original system. Markov chain
approximations are used. They have the structure of the original
problem, but are generally much simpler. The numerical data shows that
performance can be greatly improved over standard operating procedures
by the use of optimal controls or reasonable approximations to them.
Details algorithms for 4D control problems are discussed. For high
dimensional models, the numerical approximation might have millions of
states. One needs to compute quantities which are the equivalent of
probabilities of the order of 10<sup>-6</sup> or smaller. Once the basic
form of the mathematical algorithm is fixed, efficiency in coding is
essential. General software codes are discussed. The effectiveness of
multigrid-type solution methods is demonstrated as well its limitations.
We also investigate the performance of dynamic memory allocation
Decision and Control, 1994., Proceedings of the 33rd IEEE Conference on; 01/1995
[Show abstract][Hide abstract] ABSTRACT: This paper describes the practical design considerations of a low torque ripple permanent magnet synchronous motor (PMSM) drive for electric power steering (EPS) application. The impact of various controller elements on torque ripple performance is discussed in detail. The experimental results show that the low cost dc-link current sensing scheme used in the design can achieve excellent and consistent torque ripple performance (less than 2% peak-to-peak at 1 N.m.), and is well suited for EPS application.
Applied Power Electronics Conference and Exposition, 2004. APEC '04. Nineteenth Annual IEEE; 02/2004
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