The Science Journal of the American Association for Respiratory Care
Background: The Dynemo 3000 (DYN) (Sometec Inc., Stoneham, MA) uses a transesphageal probe and Doppler technology to determine cardiac output (CO). We performed this investigation to compare measurements made by DYN with those obtained from thermodilution (TD) by a pulmonary artery (PA) catheter. Since this device measures only CO flowing through the descending aorta, we felt that the device would be of benefit to our practice if (TD-DYN) bias was between 25-35% and precision was less than 1.5 L/min.
Methods: After obtaining permission from the IRB a total of 11 measurements were obtained from 5 patients in an ICU setting. All patients were orally intubated, sedated and had a PA catheter. The DYN probe was inserted through the oral cavity and into the esophagus. The aortic diameter was determined by Doppler method and CO was calculated by measuring flow through the descending aorta. DYN CO was recorded while TD CO was taken to be the result of the mean of the 2nd and 3rd PA catheter injections. Data analysis included simple regression. A Bland - Altman plot was constructed (see Fig. 1)..
Results: Mean bias: 4.19 L/min. Precision (+/-2STD): 3.34. Correlation coefficient (r2): 0.028.
Conclusion: The data from the Dynemo exceeded the range of bias and precision that would have made it useful to our practice.
(See Original for Figure)