Ventilatory and hemodynamic effects of continuous positive airway pressure in dogs with acute cardiogenic pulmonary edema

Objective To investigate the ventilatory and hemodynamic effects of continuous positive airway pressure(CPAP) in acute cardiogenic pulmonary edema(ACPE) in dogs. Methods Cardiac output(CO),heart rate(HR),blood pressure(BP),pulmonary artery wedge pressure(PAWP),central venous pressure(CVP) and intrathoracic negative pressure(Pt) were measured. These parameters were recorded at spontaneous breath,5 cm H2O,10 cm H2O,and 15 cm H2O CPAP in ten dogs before(healthy state) and after the induction of ACPE. Results When ACPE occurred,the dogs showed rapid breath,higher Pt[(-(10.90)±0.75) versus-(4.90±0.09)cm H2O],decreased CVP and CO[(10.1±0.4) versus ((8.0±)0.7)mm Hg and (1.52±0.13) versus (0.85±0.09)L/min,respectively],increased PAWP[(9.64±0.54) versus (17.77±0.79)mm Hg,all P0.05]. The correlation coefficient of the change of CVP and the change of Pt was 0.78(P0.01). The addition of 5 or 10 cm H2O CPAP decreased Pt[-(6.53±0.11),-(5.14±0.25)cm H2O],which resulted in increased cardiac function. CO was also increased[(1.45±0.11),(1.24±0.11)L/min],with decreased PAWP[(15.80±0.55),(17.40±0.70)mm Hg;P0.05]. After the application of 15 cm H2O CPAP,Pt reached nearly zero[-(0.82±0.37)cm H2O],CO decreased to (0.82±0.07)L/min and PAWP increased to (19.23±0.73)mm Hg(P0.05). Conclusions ACPE induced rapid breath,elevated Pt and decreased CVP and CO. Proper CPAP can improve CO by regulating Pt,hence the improvement of other hemodynamic parameters.