QUARTERLY FOCUS ISSUE: HEART FAILURE Hypoxia, Not the Frequency of Sleep Apnea, Induces Acute Hemodynamic Stress in Patients With Chronic Heart Failure

Methods Sixty-four HF patients with New York Heart Association functional class II and III HF and ejection fraction !40% underwent a baseline sleep study. Five patients with no sleep apnea and 12 with severe sleep apnea underwent repeat sleep studies, during which blood was collected every 20 min for the measurement of BNP. Patients with severe sleep apnea also underwent a third sleep study with frequent BNP measurements while they were administered oxygen. This provided 643 observations with which to relate apnea to BNP. The association of log BNP with each of 6 markers of apnea severity was evaluated with repeated measures regression models.