Fluctuating Flow. Vibrato, Tremolo, or Upper Airway Oscillation (original) (raw)
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Characteristics and Consequences of Non-apneic Respiratory Events During Sleep
Rationale: Current scoring criteria of non-apneic events (ie, hypopnea) require the presence of oxyhemoglobin desaturation and/or arousal. However, other sleep study parameters may help to identify abnormal respiratory events (REs) and assist in making more accurate diagnosis. Objectives: To investigate whether non-apneic REs without desaturation or cortical arousal are associated with respiratory and cardiac consequences. Methods: Thirteen participants with sleep disturbances (snoring and/or excessive day time sleepiness), were screened using attended in laboratory pol-ysomnography (PSG) while monitoring pressure and airflow via a nasal mask with an attached pneumotach. To separate the contribution of the upper airway resistance (R UA) and total pulmonary resistance (R L), supraglottic and esophageal pressures were measured using Millar pressure catheters. R L and R UA were calculated during baseline and hypopneas. R L was defined as the resistive pressure divided by the maximal flow during inspiration and expiration. Hypopnea was defined 30% decrease in flow with 3% desaturation and/or cortical arousal. REs was defined as 30% decrease in the flow without desaturation and/or cortical arousal. In eight subjects continuous positive airway pressure (CPAP) was titrated to optimal pressure. R-R interval (RRI) was defined as consecutive beat-to-beat intervals on single lead electrocardiograph (ECG) during baseline, RE/hypopnea and on optimal CPAP. Results: REs associated with increased expiratory R UA (14.6 ± 11.3 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), and increased expiratory R L relative to baseline (29.2 ± 14.6 vs. 20.9 ± 11.0 and 23.7 ± 12.1 vs. 14.3 ± 5.6 cmH 2 O L −1 s −1 during inspiration and expiration, respectively; p < .05). RRI decreased significantly following RE and hypopnea relative to baseline (804.8 ± 33.1 vs. 806.4 ± 36.3 vs. 934.3 ± 45.8 ms; p < .05). Optimal CPAP decreased expiratory R UA (4.0 ± 2.5 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), decreased inspiratory R L (12.6 ± 14.1 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), and allowed RRI to return to baseline (p < .05). RRI dips index was an independent predictor of sleep-disordered breathing (SDB) when non-apneic REs were accounted for in symptomatic patients (p < .05). Conclusions: Non-apneic REs without cortical arousal or desaturation are associated with significant respiratory and heart rate changes. Optimal CPAP and the reduction of resistive load are associated with the normalization of heart rate indicating potential clinical benefit.
The sleep apnoea-hypopnoea syndrome is characterised by recurrent obstructions of the upper airway, resulting in sleep disruption and arterial oxygen desaturations. Noninvasive assessment of respiratory mechanics during sleep is helpful in facilitating the diagnosis and treatment of patients with sleep apnoea-hypopnoea syndrome. This series summarises the different tools that are currently available to noninvasively assess respiratory mechanics during sleep breathing disturbances. These techniques are classified according to the main variable monitored: ventilation, breathing effort or airway obstruction. Changes in patient ventilation are assessed by recording flow or volume signals by means of pneumotachographs, thermistors or thermocouples, nasal prongs or thoraco-abdominal bands. Common tools to noninvasively assess breathing efforts are the thoraco-abdominal bands and the pulse transit time technique. Upper airway obstruction is noninvasively characterised by its upstream resistance and its critical pressure or by means of the forced oscillation technique. Given the technical and practical limitations of each technique, combining different tools improves the reliability and robustness of patient assessment during sleep.
Immediate consequences of respiratory events in sleep disordered breathing
Sleep Medicine, 2005
Background: In obstructive sleep apnea/hypopnea syndrome, immediate physiological consequences of events have a dual role: censoring artifacts and gauging physiological significance. Newer airflow monitors may have changed the relative importance of these functions. The purpose of this study was to determine the frequency and hierarchy of occurrence of oxygen desaturation, EEG arousal and heart rate changes as immediate consequences of respiratory events.
CHEST Journal, 2011
O bstructive sleep apnea syndrome (OSAS) is a major public health problem with a prevalence estimated at approximately 4% of adults in both Western and Asian countries. 1,2 Nasal continuous positive airway pressure (CPAP) therapy for OSAS has been the most effective and widely used treatment. However, approximately 25% to 50% of patients with OSA will either refuse to try or will not tolerate CPAP therapy. 6 Furthermore, some patients do not respond to CPAP treatment, either without symptom improvements or without reductions in overall respiratory events. Finally, central apneas can emerge with initiation of CPAP therapy, a condition that has been called "complex sleep apnea." 7 Taken together, these facts indicate signifi cant variability of the OSAS phenotype.
Nonrandom variability of respiration during sleep in healthy humans
Sleep, 2005
Breath-to-breath variability is not purely random but is, instead, characterized by correlations on short- and long-term scales. Short-term correlations might reflect intact metabolic-control mechanisms. To investigate whether the higher variability of breathing during rapid eye movement (REM) compared to non-REM (NREM) sleep is of random or nonrandom nature--reflecting an altered respiratory control--short-term and long-term correlations of respiratory drive and timing were determined. A full-night polysomnogram with a pneumotachograph attached to a full-face mask was performed. For each breath during NREM and REM sleep, respiratory components were analyzed based on the quantitative airflow. Data collection took place in the sleep laboratory. Twenty-nine healthy subjects (age, 25.8 +/- 3.1 years). Long-term correlations are practically absent in respiratory timing and drive components during NREM sleep, whereas they are present during REM sleep. Short-term correlations are present ...
The upper airway in sleep: physiology of the pharynx
Sleep Medicine Reviews, 2003
The upper airway is the primary conduit for passage of air into the lungs. Its physiology has been the subject of intensive study: both passive mechanical and active neural in¯uences contribute to its patency and collapsibility. Different models can be used to explain behavior of the upper airway, including the``balance of forces'' (airway suction pressure during inspiration versus upper airway dilator tone) and the Starling resistor mechanical model.