Organ blood flow and cardiovascular effects of high-frequency oscillation versus conventional ventilation in dogs with right heart failure.

Mongrel dogs underwent a large (apex to pulmonary valve) right ventriculotomy to produce right ventricular dysfunction. Right ventriculotomy decreased cardiac output from 2.47 +/- 0.43 to 1.34 +/- 0.16 L/min (p less than .01), increased CVP from 3.7 +/- 1.5 to 8.3 +/- 2.4 mm Hg (p less than .01), and decreased mean systemic arterial pressure (MAP) from 143 +/- 16 to 121 +/- 21 mm Hg (p less than .01). There was no effect on mean pulmonary artery pressure (MPAP) or pulmonary artery occlusion pressure. After stabilization a randomized crossover controlled comparison of conventional mechanical ventilation (CMV) and high-frequency oscillation (HFO) was performed. FIO2, pH, PCO2, core temperature, and preload were held constant. Mean airway pressure (Paw) was 4.8 +/- 0.7 cm H2O on CMV vs. 3.5 +/- 1.0 cm H2O on HFO (p less than .05). There was no difference in PaO2. We found no statistically significant differences between the two modes of ventilation with respect to cardiac output, MAP, MPAP, systemic vascular resistance, and pulmonary vascular resistance. Blood flows to cerebral cortex, renal cortex, adrenal, hepatic artery, left ventricular myocardium, and skeletal muscle were not different when comparing CMV to HFO. Despite the ability to attain equivalent oxygenation and ventilation at lower Paw, HFO offers no hemodynamic advantage over CMV in the presence of right ventricular dysfunction.