阻塞性睡眠呼吸暂停（OSA）和中枢性睡眠呼吸暂停（CSA）大量存在于慢性心力衰竭（CHF）患者中，且会使CHF的预后变差。CHF患者普遍存在体液潴留。目前已明确体液转移可引起或加重OSA，且可能对CSA也存在影响。但是体液转移促使CHF患者发生OSA和CSA的确切机制尚不够明了。我们的预实验发现体液转移对于OSA可能是通过增加颈部软组织水分而引起上气道狭窄和阻力增加；但对于CSA则可能主要是通过增加化学敏感性（动脉血CO2分压的波动）、影响循环的稳定性（循环时间）和呼吸的稳定性（环路增益）等使其加重。因此我们认为需要进一步探讨和阐明这种差异。本研究拟通过观察CHF合并OSA或CSA患者夜间体液转移对上气道管腔形态及周围软组织水分、上气道阻力、夜间动脉血CO2分压、循环时间、环路增益等的影响，探讨体液转移对OSA和CSA的不同作用机制，为临床病因治疗提供理论依据。

Both obstructive sleep apnea (OSA) and central sleep apnea (CSA) are common in patients with chronic heart failure (CHF) and can worsen the prognosis of CHF. Fluid retention is also commmon in CHF patients. Up to now it has been confirmed that fluid shift can induce or aggravate OSA and play some roles in pathogenesis of CSA. However, the exact mechanism about how fluid shift cause OSA and CSA in CHF patients are not clear. Our pre-experiment suggested the pathways for fluid shift to induce OSA or CSA were different. For OSA, it was possibly because shifted fluid accumulated in the neck, and narrowed the upper airway; however, for CSA the effect of nocturnal fluid shift may because of increasing of chemosensitivity (fluctuation of PaCO2), circulation delay and hemodynamic disordered. To provide theoretic basis for specific treatments for OSA and CSA in CHF patients, this study is aimed to explore the different mechanisms 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 loop gain.