A CYCLIC BREATHING PATTERN IN PATIENTS WITH POOR LEFT-VENTRICULAR FUNCTION AND COMPENSATED HEART-FAILURE - A MILD FORM OF CHEYNE-STOKES RESPIRATION

Objectives. This study was designed to evaluate the breathing patterns of patients with poor left ventricular systolic function and compensated heart failure. Background. Cheyne-Stokes respiration is often found in patients with severe decompensated heart failure. Breathing patterns of patients with clinically moderate congestive heart failure have not been well described. Methods. Tidal volume, oxygen consumption, carbon dioxide production, respiratory rate, minute ventilation and partial pressure of end-tidal oxygen and of end-tidal carbon dioxide were measured in 36 consecutive patients with an ejection fraction <40% and compensated congestive heart failure. Measurements were made with a computerized expiratory gas analyzer. Results. Nine of the 36 patients demonstrated a cyclic breathing pattern, with a cycle length of 130 +/- 82 s. At the peak of the cycle, minute ventilation was 16.7 +/- 2.9 liters/min, tidal volume was 582 +/- 130 ml, end-tidal carbon dioxide was 25 +/- 2.7 mm Hg and end-tidal oxygen was 121 +/- 4.9 mm Hg. At the nadir of the cycle, minute ventilation was 9.5 +/- 2.1 liters/min, tidal volume was 372 +/- 120 ml, end-tidal carbon dioxide was 35 mm Hg +/- 2.1 and end-tidal oxygen was 101 +/- 3.9 mm Hg. Respiratory rate was 27 +/- 5.9 breaths/min at peak and 24 +/- 5.1 breaths/min at nadir (p = NS). Patients with a cyclic respiratory pattern had a significantly lower ejection fraction (15 +/- 5%) compared with patients without cyclic respirations (26 +/- 8%; p < 0.001). There was no difference in the origin of heart failure, clinical status or exercise performance between these two groups. Conclusions. A cyclic respiratory pattern occurs commonly in patients with mild to moderate heart failure. It is related to poor left ventricular systolic function and not related to clinical status or etiology of heart failure. The cyclic respiratory pattern found commonly in patients with compensated heart failure and very poor ventricular function (ejection fraction <25%) consists of a variation in tidal volume only. Respiratory rate is relatively constant and true apnea does not occur.