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1.
The amount of fluid displaced overnight from the legs into the neck as a consequence of lying recumbent correlates with the number of apneas and hypopneas per hour of sleep (AHI). Sedentary living promotes dependent fluid accumulation in the legs that can be counteracted by venous compression of the legs (compression stockings). We hypothesized that, in non-obese sedentary men with obstructive sleep apnea (OSA), wearing compression stockings during daytime will reduce the AHI by reducing the amount of fluid available for the displacement into the neck overnight. Polysomnography and measurement of overnight changes in leg fluid volume and neck circumference were performed at baseline and after one day of legs venous compression. The median AHI decreased from 30.9 (interquartile range 19.6-60.4) to 23.4 (12.9-31.8) (P=0.016) in association with a median 40% reduction in the change in leg fluid volume (P=0.016) and a median 42% reduction in the increase in neck circumference (P=0.016). These results provide proof-of-principle that overnight fluid displacement into the neck plays a causative role in OSA.  相似文献   

2.
Recently we showed that fluid accumulation in the neck can narrow the upper airway (UA) and increase its collapsibility, which may exacerbate obstructive sleep apnea (OSA). However, the available methods for measuring neck fluid volume (NFV) are inconvenient and expensive. Narrowing of the UA due to fluid accumulation could change acoustic characteristics of respiratory sounds. In this study, we developed a novel approach for non-invasive estimation of NFV from acoustic measurements. Twenty-eight healthy subjects lay awake and supine for 90 min while NFV and tracheal sounds were measured simultaneously using bioimpedance and a microphone, respectively. Sets of tracheal sound features were calculated in time and frequency domains and were reduced using methods based on regression and minimum-redundancy-maximum-relevance. The resulting feature sets were applied to a multi-linear regression and a mixture-density neural network to estimate NFV. Our results show very small relative estimation errors of 1.25 and 3.23%, based on the regression and neural network methods, respectively. These results support the practical application of this technology in diagnosing fluid accumulation in the neck and its possible contributions to the pathogenesis of OSA.  相似文献   

3.
In eight healthy volunteers undergoing 16 experiments in a cross-over design central venous pressure (CVP) and atrial natriuretic factor (ANF) in central venous plasma were measured during a 30 min control period followed by three separated periods of 10 min lower-body positive pressure (LBPP) or 90 min continuous LBPP induced by inflation of a military anti-G suit to evaluate the effect of short repeated and of extended increases in right atrial pressure on plasma ANF levels. CVP increased significantly during each of three separate periods of intermittent LBPP, and 15 min after application of continuous LBPP (P less than 0.025 for all). Blood pressure and heart rate did not change. During intermittent LBPP plasma ANF levels increased 10 min after the first inflation of the MAGT-suit (P = 0.013), but not after the second or third inflation. During continuous LBPP plasma ANF remained unchanged until 90 min after application of LBPP where a significant rise was observed (P = 0.023). The data demonstrate that the ANF response to short-term increases in right atrial pressure, as small as 2.5 mmHg, is maximal within 10 min and that repeated pressure stimuli may decrease ANF release. Sustained increases in right atrial pressure are not associated with increases in plasma ANF until long after initiation of the pressure stimulus suggesting rapid receptor-binding of ANF and that the ANF receptors might be saturated during continuously elevated ANF levels.  相似文献   

4.
Obstructive sleep apnea (OSA) is a common and underdiagnosed medical disorder. OSA is associated with the symptoms of excessive daytime sleepiness (EDS). These patients typically follow a sedentary lifestyle, and sedentary behavior is related to impaired fluid dynamics in the lower body, particularly the legs. In a supine position this fluid can move towards the neck, with a subsequent increase in upper airway (UA) resistance and UA collapse. Several studies have shown that rostral fluid shift worsens OSA; however, whether physical activity can influence this has not been tested.  相似文献   

5.
Walsh JH  Maddison KJ  Platt PR  Hillman DR  Eastwood PR 《Sleep》2008,31(10):1440-1447
STUDY OBJECTIVES: To determine the effect of head posture on upper airway collapsibility and site of collapse of the passive human upper airway. DESIGN: Pharyngeal critical closing pressure (Pcrit) and site of airway collapse were assessed during head flexion, extension and rotation in individuals undergoing propofol anesthesia. SETTING: Operating theatre of major teaching hospital. PARTICIPANTS: Fifteen healthy volunteers (8 male), including 7 who were undergoing surgery unrelated to the head or neck. MEASUREMENTS AND RESULTS: Applied upper airway pressure was progressively decreased to induce variable degrees of inspiratory flow limitation and to define Pcrit. Upper airway and oesophageal pressure transducers identified the site of collapse. Genioglossus muscle activity (EMGgg) was assessed using intramuscular fine wire electrodes inserted percutaneously. Data from 3 subjects were excluded from analysis due to persistent EMGgg. In the neutral posture Pcrit was -0.4 +/- 4.4 cm H2O and collapsed most frequently in the velopharyngeal region. Relative to neutral, Pcrit increased to 3.7 +/- 2.9 cm H2O (P < 0.01) and decreased to -9.4 +/- 3.8 cm H2O (P < 0.01) when the head was flexed and extended, respectively but was unchanged by rotation (-2.6 +/- 3.3 cm H2O; n = 10; P = 0.44). The site of collapse varied, in no consistent pattern, with change in head posture in 5 subjects. CONCLUSIONS: Head posture has a marked effect on the collapsibility and site of collapse of the passive upper airway (measured by EMGgg) indicating that controlling head posture during sleep or recovery from anesthesia may alter the propensity for airway obstruction. Further, manipulating head posture during propofol sedation may assist with identification of pharyngeal regions vulnerable to collapse during sleep and may be useful for guiding surgical intervention.  相似文献   

6.
Controversy exists whether recruitment of a large muscle mass in dynamic exercise may outstrip the pumping capacity of the heart and require neurogenic vasoconstriction in exercising muscle to prevent a fall in arterial blood pressure. To elucidate this question, seven healthy young men cycled for 70 minutes at a work load of 5540%VO2max. At 30 to 50 minutes, arm cranking was added and total work load increased to (mean ± SE) 82 ± 4% of Vo2max. During leg exercise, leg blood flow average 6.15 4.511 minutes-1, mean arterial blood pressure 137 ± 4 mmHg and leg conductance 42.3 ± 2.2 ml minutes-1 mmHg-1. When arm cranking was added to leg cycling, leg blood flow did not change significantly, mean arterial blood pressure increased transiently to 147 ± 5 mmHg and leg vascular conductance decreased transiently to 33.5 ± 3.1 ml minutes-1 mmHg-1. Furthermore, arm cranking doubled leg noradrenaline spillover. When arm cranking was discontinued and leg cycling continued, leg blood flow was unchanged but mean arterial blood pressure decreased to values significantly below those measured in the first leg exercise period. Furthermore, leg vascular conductance increased transiently, and noradrenaline spillover decreased towards values measured during the first leg exercise period. It is concluded that addition of arm cranking to leg cycling increases leg noradrenaline spillover and decreases leg vascular conductance but leg blood flow remains unchanged because of a simultaneous increase in mean arterial blood pressure. The decrease in leg vascular conductance observed when arm cranking increased mean arterial blood pressure could be regarded more as a measure to prevent overperfusion than a measure to maintain arterial blood pressure.  相似文献   

7.
Obstructive Sleep apnea can be caused by fluid shift from the legs to the neck that narrows the upper airway (UA) and contributes to changes in tracheal sound. Tracheal sound is generated from the turbulent airflow in the pharynx and respiratory airways and it has recently been used to estimate increases in neck fluid volume (NFV). However, tracheal sound is also highly variable among people, especially across the sexes. In this paper, a novel method is proposed to select tracheal sound features towards estimating NFV in men and women separately. To validate this method, it was applied to the tracheal sound data of 28 healthy individuals. Our proposed feature selection algorithm is based on sparse representations and incorporates NFV to maximize the relevance of selected features. This feature selection eliminates the dependence of the previous methods on calibrating the model for every individual. Two models, regression and Kalman filters, are then used to estimate NFV from selected features. Kalman filter obtains the highest performance, estimating NFV with more than 90% accuracy in both men and women. This algorithm can be used to develop non-invasive acoustic technologies to investigate the effects of fluid on UA anatomy in general applications. These results could be used to develop convenient devices to monitor the neck edema and its contribution to sleep apnea severity in fluid retaining patients such as heart or renal failure.  相似文献   

8.
In 8 patients with moderate hypertension and 8 normotensive subjects an attempt was made to study the circulatory effects of high and low pressure baroreceptor stimulation. Intrathoracic low pressure receptors were stimulated by changes in blood volume distribution using lower body negative pressure (LBNP) and lower body positive pressure (LBPP). The carotid sinus was stimulated by sinusoidal neck suction. Blood pressure, central venous pressure, heart rate, cardiac output and forearm blood flow were recorded. During LBNP and LBPP changes in central blood volume, reflected in changes in central venous pressure, induced significantly greater changes in cardiac output and forearm blood flow in the hypertensive subjects. In both normotensive and hypertensive subjects mean arterial blood pressure was essentially unchanged during LBNP and a slight increase was found during LBPP. Heart rate and blood pressure response to stimulation of the carotid sinus decreased with increasing resting mean arterial pressure. The results suggest impairment of reflex adjustments, via arterial baroreceptors, possibly in particular to dynamic stimuli, rather than via intrathoracic “low pressure” baroreceptors in subjects with moderate hypertension.  相似文献   

9.

Study Objectives:

In children, most obstructive events occur during rapid eye movement (REM) sleep. We hypothesized that children with the obstructive sleep apnea syndrome (OSAS), in contrast to age-matched control subjects, would not maintain airflow in the face of an upper airway inspiratory pressure drop during REM sleep.

Design:

During slow wave sleep (SWS) and REM sleep, we measured airflow, inspiratory time, inspiratory time/total respiratory cycle time, respiratory rate, tidal volume, and minute ventilation at a holding pressure at which flow limitation occurred and at 5 cm H2O below the holding pressure in children with OSAS and in control subjects.

Setting:

Sleep laboratory.

Participants:

Fourteen children with OSAS and 23 normal control subjects.

Results:

In both sleep states, control subjects were able to maintain airflow, whereas subjects with OSAS preserved airflow in SWS but had a significant decrease in airflow during REM sleep (change in airflow of 18.58 ± 12.41 mL/s for control subjects vs −44.33 ± 14.09 mL/s for children with OSAS, P = 0.002). Although tidal volume decreased, patients with OSAS were able to maintain minute ventilation by increasing the respiratory rate and also had an increase in inspiratory time and inspiratory time per total respiratory cycle time

Conclusion:

Children with OSAS do not maintain airflow in the face of upper-airway inspiratory-pressure drops during REM sleep, indicating a more collapsible upper airway, compared with that of control subjects during REM sleep. However, compensatory mechanisms exist to maintain minute ventilation. Local reflexes, central control mechanisms, or both reflexes and control mechanisms need to be further explored to better understand the pathophysiology of this abnormality and the compensation mechanism.

Citation:

Huang J; Karamessinis LR; Pepe ME; Glinka SM; Samuel JM; Gallagher PR; Marcus CL. Upper airway collapsibility during REM sleep in children with the obstructive sleep apnea syndrome. SLEEP 2009;32(9):1173-1181.  相似文献   

10.
The critical pressure at which the pharynx collapses (Pcrit) is an objective measurement of upper airway collapsibility, an important pathogenetic factor in obstructive sleep apnoea. This study examined the inherent variability of passive Pcrit measurement during sleep and evaluated the effects of sleep stage and body posture on Pcrit. Repeated measurements of Pcrit were assessed in 23 individuals (15 male) with diagnosed obstructive sleep apnoea throughout a single overnight sleep study. Body posture and sleep stage were unrestricted. Applied upper airway pressure was repetitively reduced to obtain multiple measurements of Pcrit. In 20 subjects multiple measurements of Pcrit were obtained. The overall coefficient of repeatability for Pcrit measurement was 4.1 cm H2O. Considering only the lateral posture, the coefficient was 4.8 cm H2O. It was 3.3 cm H2O in the supine posture. Pcrit decreased from the supine to lateral posture [supine mean 2.5 cm H2O, 95% confidence interval (CI) 1.4–3.6; lateral mean 0.3 cm H2O, 95% CI ?0.8–1.4, P = 0.007] but did not vary with sleep stage (P = 0.91). This study has shown that the overall coefficient of repeatability was 4.1 cm H2O, implying that the minimum detectable difference, with 95% probability, between two repeated Pcrit measurements in an individual is 4.1 cm H2O. Such variability in overnight measures of Pcrit indicates that a single unqualified value of Pcrit cannot be used to characterize an individual’s overall collapsibility during sleep. When within‐subject variability is accounted for, change in body posture from supine to lateral significantly decreases passive pharyngeal collapsibility.  相似文献   

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