Fluid retention in the legs due to chronic heart failure (CHF) during the daytime may redistribute to neck when with supine positioning at night. A portion of the shifted fluid accumulates in the neck, and narrows the upper airway, predisposing the patient to obstructive sleep apnea (OSA) and central sleep apnea (CSA). However, the mechanism of overnight fluid shift on OSA and CSA remains unclear. The investigators pre-experiment demonstrated there may be a different mechanism of overnight fluid shift on OSA and CSA. The accumulation of water content in neck soft tissue increases neck circumference and leads to pharyngeal resistance, upper airway collapse and causes OSA. The effect of nocturnal fluid shift on CSA may be because of increasing of chemosensitivity (fluctuation of PaCO2), circulation delay and hemodynamic disordered. This study is aimed to explore the different mechanism of overnight fluid shift on OSA and CSA by comparing the changes of upper airway (inside diameter, water content, and pharyngeal resistance), PaCO2, circulation delay (lung-to-finger circulation time) and hemodynamic (loop gain).
Age range
18 Years – 70 Years
Sex
ALL
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nocturnal fluid shift, as determined by change in leg fluid volume
Timeframe: up to 24 months
pharyngeal resistance,as the change from baseline in pharyngeal air-flow resistance
Timeframe: up to 24 months
Lung to Finger Circulation Time
Timeframe: up to 24 months
Loop Gain
Timeframe: up to 24 months
apnea-hypopnea index, as the severity of sleep apnea.
Timeframe: up to 24 months