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 matched 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 transmural pressure during systole (LVPtmsys)[
p < 0.05], but in CHF patients, 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/m2 vs−
0.15 ± 0.11 L/min/m2 [p < 0.05], respectively).
Healthy subjects recovered promptly, but in CHF patients, these adverse
hemodynamic effects were sustained following release of the MM.
Conclusions: CHF patients experience more pronounced and
sustained reductions in BP and cardiac output both during and following
the MM than do healthy subjects. These findings suggest the potential
for adverse hemodynamic effects and aftereffects of negative
intrathoracic pressure generation during obstructive sleep apnea in
patients with CHF.