Cardiac output during total hip replacement in dogs;: comparison of trans-oesophageal pulsed-wave Doppler echocardiography and thermodilution

Trans-oesophageal pulsed-wave Doppler echocardiography was evaluated as a noninvasive method of determining cardiac output during total hip replacement in 10 dogs. Cardiac output was estimated by determining the cross-sectional area of the aorta via caudal transverse echocardiography and the outflow velocity of the ascending aorta via cranial transverse Doppler echocardiography. Thermodilution was used as the reference method. In addition, cardiopulmonary changes at the time of femoral prosthesis insertion, were determined. Comparison of 160 measurements yielded a correlation coefficient of 0.48. Linear regression analysis revealed the equation, cardiac output (Doppler echocardiography) = 0.45 cardiac output (thermodilution) + 3.3. There was a significant decrease in the partial pressure of carbon dioxide at end-exspiration (PETCO2), the systolic arterial blood pressure (mmHg) and the invasive stroke volume (ml/beat/m(2)) and a significant increase in the pulmonary vascular resistance (dynes/sec/cm(5)) immediately after insertion of the femoral prosthesis.