Two-dimensional echocardiographic evaluation of inferior vena cava, right ventricle, and left ventricle during positive-pressure ventilation with varying levels of positive end-expiratory pressure.

The effects of intermittent positive-pressure ventilation (IPPV) with 0, 10, and 15 cm H2O of PEEP on inferior vena cava (IVC), right and left ventricular length and septal-lateral dimensions, and cardiac output were examined in 19 patients with respiratory failure using two-dimensional echocardiography. In five patients, cardiac output was also obtained by the thermodilution technique. As PEEP was increased, IVC dimensions increased during both inspiration and expiration, and the IVC collapsibility index decreased. This indicated an increase in venous stasis and decrease in venous return to the right atrium. Increasing PEEP was associated with progressive decreases in cardiac output, and length and septal-lateral dimensions of both ventricles. The decreased cardiac output during IPPV with 10 and 15 cm H2O PEEP may be due to the decreased venous return and ventricular filling. Cardiac output determined by echocardiography was correlated closely to that by the thermodilution technique.