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Query: UMLS:C0037315 (sleep apnea)
 8,000 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Snoring was described in literature even before medicine. Common definitions do not consider acoustic measurements of snoring. In this paper we discuss the main pathophysiological aspects of snoring and the snoring-sleep relationship as the generating mechanisms. Snoring can be analysed and measured by the following methods: 1) Leq-Equivalent Continuous Sound Level, which only quantifies noisiness, annoyance, and damage to the partner's and snorer's hearing; 2) Power Spectrum, with frequency values, formantic structure data and typical shape, which can help to distinguish simple snoring from heavy snoring with obstructive sleep apnoea syndrome (OSAS); 3) Linear Prediction Code (LPC) method, which can define the cross-sectional area (CSA) of the upper airways and which locates sites of obstruction. Simulated snoring analysis with LPC and with simultaneous fluoroscopy permits the definition of CSA and the identification of three snoring patterns: nasal, oral and oronasal. Snoring is an important sign of sleep-related breathing disorders (SRBD), of the upper airway resistance syndrome (UARS), and of the OSAS. Snoring is a symptom of nasal obstruction and is associated with cardiovascular diseases and nocturnal asthma as a trigger or causative factor; however, its acoustic features in these disorders are not well-defined. Home monitoring of snoring is very useful for epidemiology and is mandatory, together with heart rate and arterial oxygen saturation (Sa,O2), to screen SRBD.
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PMID:Snoring: analysis, measurement, clinical implications and applications. 883 48

Arterial blood pressure is influenced by sleep-related breathing disorders. As cardiovascular consequences can be diagnosed by an accurate recording and analysis of blood pressure, new recording methodologies and an approach to analysis are presented here. Invasive continuous blood pressure recording is the common reference for all methodologies. As blood pressure varies rapidly in parallel with sleep-related breathing disorders it is indispensible to record blood pressure continuously. To introduce non-invasive methodology the Finapres system was used during sleep studies; a validation study showed severe limitations. This study was followed by the validation of an improved system called Portapres, which is portable, has two finger cuffs and a hydrostatic height compensation. Analysis of continuous blood pressure in patients with sleep apnoea is carried out to detect mechanisms which influence the cardiovascular risk. Spectrum analysis of systolic blood pressure showed two different major oscillations present in patients with obstructive sleep apnoea. One oscillation (<0.06 Hz) occurs in parallel with each apnoeic episode and the other oscillation (0.2-0.4 Hz) occurs in parallel with the obstructive efforts during each apnoea and in parallel with respiration during periods of snoring. These two oscillations were so specific that the use of non-invasive continuous blood pressure recording allowed an estimation of the extent of underlying breathing disorders, and assessment of cardiovascular risk in a patient with obstructive apnoea in terms of hypertension and on the basis of ambulatory monitoring.
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PMID:Blood pressure analysis. 1060 67

This paper first describes the AM-FM demodulation of an arterial pressure signal. Although it is known to be efficient on signals modulated by breathing, we demonstrate that in case of lack of respiratory modulation (real or simulated central sleep apnea), the AM-FM algorithm doesn't perform well in heart rate extraction. We introduce then a new algorithm based on Singular Spectrum Analysis eigenvalues which performs better cardiac frequency estimation in this context. Respiratory estimation is possible but is beyond the scope of this paper. The error for cardiac frequency estimation is around 0.2 BPM (Beats Per Minute) versus 5.5 BPM for the AM-FM demodulation. Further experimentations will be performed (with this time both cardiac and respiratory assessments) and will deal with real sleep apnea cases.
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PMID:Pulse rate analysis in case of central sleep apnea: a new algorithm for cardiac rate estimation. 1996 48