[Effect of CPAP and BIPAP on stroke volume in patients with obstructive sleep apnea syndrome]

We studied the effect of CPAP and BIPAP on cardiac output (CO) in 23 male obstructive sleep apnea (OSAS) patients with cardiac history but without congestive heart failure (CHF) during wakefulness using the thermodilution method. CPAP was applied at 10 cm H2O and 15 cm H2O, BIPAP at 10/0 cm H2O and 15/10 cm H2O. CO only decreased significantly by 14.6 +/- 11.8% at 15 cm H2O CPAP and by 13.4 +/- 10.0% at 15/10 cm H2O BIPAP. CPAP and BIPAP did not differ in altering hemodynamics. So sleep apnea patients without CHF develop no severe decrease of CO during nasal positive pressure ventilation up to 15 cm 2O.