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 c ompliance (60 +/- 10 ml/cm H2O to 87 +/- 20 ml/cm H2O, p < 0.05) and i n 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/mi n 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/m in, p < 0.05), without significant changes in breathing pattern. Despi te a significant reduction in the negative swings in intrathoracic pre ssure (15.2 +/- 1.9 cm H2O to 10.8 +/- 1.8 cm H2O, p < 0.001), no sign ificant change was observed in CI or strongest volume during CPAP. How ever, mean transmural filling pressures decreased significantly with C PAP suggesting a better cardiac performance. Neither the level of stro ke volume nor of PAOP, was predictive of changes ire tl or in stroke v olume. in patients with respiratory insufficiency caused by congestive heart failure (CHF), CPAP reduces respiratory muscle effort without a ltering cardiac output. The slight decrease in mean transmural left an d right atrial pressures suggests an improvement in cardiac performanc e.