The effect of posture on Cheyne-Stokes respirations and hemodynamics in patients with heart failure.

STUDY OBJECTIVES

Cheyne-Stokes respirations occur in 40% of patients with heart failure. Orthopnea is a cardinal symptom of heart failure and may affect the patient's sleeping angle. The objective of this study was to assess the respiratory and hemodynamic response to sleeping angle in a group of subjects with stable heart failure.

DESIGN

Twenty-five patients underwent overnight polysomnography with simultaneous and continuous impedance cardiographic monitoring. Sleeping polysomnographic and impedance cardiographic data were recorded.

SETTING

The study was conducted in a sleep center.

PATIENTS

All 25 patients had clinically stable heart failure and left ventricular ejection fractions < 40%.

INTERVENTIONS

The patients slept at 0 degrees, 15 degrees, 30 degrees, and 45 degrees in random order.

MEASUREMENTS AND RESULTS

Seventeen patients had Cheyne-Stokes apneas (index > 5/h) and 23 patients had hypopneas (index > 5/h). The hypopnea index showed no response to sleeping angle. The Cheyne-Stokes apnea index decreased with increasing sleeping angle (P < 0.001). This effect was seen only during supine sleep and non-rapid eye movement sleep and was absent in non-supine sleep, rapid eye movement sleep, and during periods of wakefulness. Thoracic fluid content index and left ventricular hemodynamics measured by impedance cardiography showed no response to sleeping angle.

CONCLUSIONS

Changing the heart failure patient's sleeping angle from 0 degrees to 45 degrees results in a significant decrease in Cheyne-Stokes apneas. This decrease occurs on a constant base of hypopneas. The changes in Cheyne-Stokes apneas are not related to changes in lung congestion and left ventricular hemodynamics.