Hemodynamic effects of simulated obstructive apneas in humans with and without heart failure

Study objectives: To determine whether generation of negative intrathoracic pressure during apnea would cause more pronounced and sustained reductions in cardiac output in patients with congestive heart failure (CHF) than in healthy subjects. Design: Physiologic intervention study. Setting: Cardiorespiratory physiology laboratory. Participants: Nine patients with CHF and nine healthy control subjects matc hed for age and sex. Interventions: Patients with CHF and healthy subjects generated - 30 cm H2O of intrathoracic pressure during 15-s Mueller maneuvers (MMs) to simulate the acute hemodynamic effects and aftereffects of obstructive apneas. Results: In both groups, MMs caused an immediate rise in left ventricular t ransmural pressure during systole (LVPtmsys) [p < 0.05], but in CHF patient s, this immediate increase was followed by a significant drop in LVPtmsys ( p < 0.05), associated with significantly greater reductions in systolic BP and cardiac index than in healthy subjects (- 25 +/- 3 mm Hg vs - 11 +/- 2 mm Hg [p < 0.05] and - 0.53 +/- 0.11 L/min/m(2) vs - 0.15 +/- 0.11 L/min/m( 2) [p < 0.05], respectively). Healthy subjects recovered promptly, but in C HF patients, these adverse hemodynamic effects were sustained following rel ease of the MM. Conclusions: CHF patients experience more pronounced and sustained reductio ns in BP and cardiac output both during and following the MM than do health y subjects. These findings suggest the potential for adverse hemodynamic ef fects and aftereffects of negative intrathoracic pressure generation during obstructive sleep apnea in patients with CHF.