摘要Background : In many animal experiments, it is vital to detect sudden changes in car-diac output (CO). This porcine study compared CO that was measured with a Swan- Ganz pulmonary catheter with the gold standard (which was a transit- time flow probe around the pulmonary artery) during interventions that caused hemodynamic instability. Methods : In one series, 7 pigs were exposed to sudden changes in CO. In another se-ries, 9 pigs experienced more prolonged changes in CO. All the pigs had a Swan- Ganz catheter placed into the pulmonary artery and a flow probe around the pulmonary artery. Adrenaline infusion and controlled hemorrhage were used to increase and de-crease CO, respectively. The measurements of CO before and after each interven-tion were compared for correlation, agreement, and the time delay that it took each method to detect at least a 30％ change in CO. A Bland– Altman test was used to identify correlations and agreements between the methods. Results : In the first series, there was a delay of 5– 7 min for the Swan Ganz catheter to register a 30％ change in cardiac output, compared with the flow probe. However, during prolonged changes in CO in the second series, there was a good correlation between the 2 methods. Mixed venous oxygen saturation reacted faster to changes than did CO; both were measured via the Swan- Ganz catheter. Conclusions : In many animal studies, the use of Swan- Ganz catheters is suitable; how-ever, in experiments with sudden hemodynamic instability, the flow probe is the most advantageous method for measuring CO.