Tagaito Y, Isono S, Remmers JE, Tanaka A, Nishino T: Lung volume and collapsibility of the passive pharynx in patients with sleep-disordered breathing
The University of Calgary, Calgary, Alberta, Canada Journal of Applied Physiology
(Impact Factor: 3.06).
11/2007; 103(4):1379-85. DOI: 10.1152/japplphysiol.00026.2007
Lung volume dependence of pharyngeal airway patency suggests involvement of lung volume in pathogenesis of obstructive sleep apnea. We examined the structural interaction between passive pharyngeal airway and lung volume independent of neuromuscular factors. Static mechanical properties of the passive pharynx were compared before and during lung inflation in eight anesthetized and paralyzed patients with sleep-disordered breathing. The respiratory system volume was increased by applying negative extrathoracic pressure, thereby leaving the transpharyngeal pressure unchanged. Application of -50-cmH(2)O negative extrathoracic pressure produced an increase in lung volume of 0.72 (0.63-0.91) liter [median (25-75 percentile)], resulting in a significant reduction of velopharyngeal closing pressure of 1.22 (0.14-2.03) cmH(2)O without significantly changing collapsibility of the oropharyngeal airway. Improvement of the velopharyngeal closing pressure was directly associated with body mass index. We conclude that increase in lung volume structurally improves velopharyngeal collapsibility particularly in obese patients with sleep-disordered breathing.
Available from: PubMed Central
- "Obesity-related reductions in lung volumes (ie, FRC and TLC) also increase passive closing pressures at the pharynx.32 Heinzer et al33 demonstrated that a 1.3 L increase in FRC during sleep decreased the apnea/hypopnea index (AHI) from 62.3 events per hour to 31.2 events per hour. "
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ABSTRACT: The obesity epidemic is a global problem, which is set to increase over time. However, the effects of obesity on the respiratory system are often underappreciated. In this review, we will discuss the mechanical effects of obesity on lung physiology and the function of adipose tissue as an endocrine organ producing systemic inflammation and effecting central respiratory control. Obesity plays a key role in the development of obstructive sleep apnea and obesity hypoventilation syndrome. Asthma is more common and often harder to treat in the obese population, and in this study, we review the effects of obesity on airway inflammation and respiratory mechanics. We also discuss the compounding effects of obesity on chronic obstructive pulmonary disease (COPD) and the paradoxical interaction of body mass index and COPD severity. Many practical challenges exist in caring for obese patients, and we highlight the complications faced by patients undergoing surgical procedures, especially given the increased use of bariatric surgery. Ultimately, a greater understanding of the effects of obesity on the respiratory disease and the provision of adequate health care resources is vital in order to care for this increasingly important patient population.
International Journal of General Medicine 10/2010; 3(4):335-43. DOI:10.2147/IJGM.S11926
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ABSTRACT: The Fourier representation of sequences plays a key roll in the analysis, the design, and the implementation of digital signal processing algorithms. The existence of very efficient algorithms for computing the Fourier transforms have expanded the importance of Fourier analysis in digital signal processing. To indicate the importance of efficient computational schemes, evaluation of two well-known algorithms - the Cooley-Tukey fast Fourier transform and complex general-N Winograd Fourier transform - were implemented on a general-purpose, high-speed, digital microprocessor - the MC68000. The Despain very fast Fourier algorithm was studied as well. Complexity measures for Fourier transforms, or the relative executional time of an implemented algorithm, have generally been based on the number of multiplications and additions required. For this reason, algorithmic improvements have primarily consisted of reduction in the number of multiplications and additions. However, large amounts of accessing and storing of data, as well as loop control overhead, are inherent in the implementation of these algorithms. Comparisons of the three algorithms as well as numerical versus data transfer operations are presented for a specific microprocessor implementation.
Acoustics, Speech, and Signal Processing, IEEE International Conference on ICASSP '81.; 05/1981
Available from: atsjournals.org
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ABSTRACT: Obstructive sleep apnea syndrome (OSAS) patients have elevated non-rapid eye movement (REM) sleep arousal thresholds to inspiratory loading. To test the hypothesis that this is due to sleep-specific dampening of cortical responses to inspiratory effort, respiratory-related evoked potentials (RREPs) were evaluated in six mild OSAS patients and six age- and body mass index-matched controls during wakefulness and Stage 2 non-REM sleep. Electroencephalogram was recorded from six scalp sites (Fz, FCz, Cz, CPz, Pz, and O(2)). Electrooculogram, electromyogram, and mask pressure signals were also recorded. During sleep, pharyngeal pressure was recorded using a Millar pressure catheter placed 2 cm below the glottis. The RREP waveform was broadly similar in the two groups during wakefulness, but was markedly different during Stage 2 non-REM sleep. During wakefulness, only the N1 component showed reduced amplitude in the OSAS group. During sleep, the occlusion stimulus elicited fewer K-complexes in the OSAS patients. In addition, the N550 component in the average of K-complex responses was smaller in amplitude in the OSAS group. The data suggest that patients with mild OSAS have a "blunted" response to the respiratory occlusion stimulus. This appears not to be related to compromised mechanoreceptor function, as the RREP was normal in the patients when they were awake.
American Journal of Respiratory and Critical Care Medicine 12/2002; 166(9):1225-34. DOI:10.1164/rccm.2106005 · 13.00 Impact Factor
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