Ventilatory and hemodynamic effects of continuous positive airway pressure in left heart failure

The ventilatory and hemodynamic effects of continuous positive airway pressure (CPAP) delivered via a face mask (at 0, 5, and 10 cm H2O, and after a return to 8 cm H2O) were studied in nine patients with acute left heart failure (pulmonary artery occlusion pressure [PAOP] greater than or equal to 18 mm Hg, and cardiac index [CI] less than or equal to 2.8 L/min/m(2)). CPAP at 10 cm H2O induced an improvement in lung compliance (60 +/- 10 ml/cm H2O to 87 +/- 20 ml/cm H2O, p < 0.05) and in lung and airway resistance (5.7 +/- 1.0 cm H2O/L/s to 3.4 +/- 1.0 cm H2O/s/min, p < 0.05), a reduction in work of breathing (18 +/- 3 J/min to 12 +/- 2 J/min, p < 0.05), and in the pressure-time index of the respiratory muscles (279 +/- 22 cm H2O/s/main to 174 +/- 25 cm H2O/s/min, p < 0.05), without significant changes in breathing pattern. Despite a significant reduction in the negative swings in intrathoracic pressure (15.2 +/- 1.9 cm H2O to 10.8 +/- 1.8 cm H2O, p < 0.001), no significant change was observed in CI or strongest volume during CPAP. However, mean transmural filling pressures decreased significantly with CPAP suggesting a better cardiac performance. Neither the level of stroke volume nor of PAOP, was predictive of changes ire tl or in stroke volume. in patients with respiratory insufficiency caused by congestive heart failure (CHF), CPAP reduces respiratory muscle effort without altering cardiac output. The slight decrease in mean transmural left and right atrial pressures suggests an improvement in cardiac performance.