OBJECTIVE: The Sometec Dynemo-3000 system allows the permanent measurement of descending aorta diameter by an echographic (A-scan) device and the blood flow velocity by a pulse Doppler velocimeter. The Dynemo-3000 then furnishes a new hemodynamic parameter, i.e., descending aortic blood flow (ABF), which is a fraction of the cardiac output (CO). We evaluate the ability of this system to measure the aortic diameter and to accurately detect ABF changes. DESIGN: A case study prospective trial. SETTING: A 24-bed medical intensive care unit of a 1,100-bed university hospital. PATIENTS: Twenty critically ill patients fully sedated, mechanically ventilated, and monitored by a pulmonary artery catheter. INTERVENTIONS: CO values determined by conventional thermodilution method (TD-CO) and ABF were recorded during the study, which included two initial baseline periods, a dobutamine infusion (5 microg/kg/min) interval of 30 mins, and a third baseline period. To assess the accuracy of A-scan, aortic diameter was measured by transesophageal echocardiography. The difference between echocardiography and A-scan was used to determine bias and precision for aortic diameter measurements. TD-CO and ABF variations were analyzed using Kruskal-Wallis and Wilcoxon tests. Association between TD-CO and ABF values was determined by calculating the linear correlation coefficient. The ability of ABF to detect a TD-CO >6.0 L/min and its variations >13% was analyzed by determination of sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values. MEASUREMENTS AND MAIN RESULTS: Aortic diameter measurements by A-scan and bidimensional methods were 23.0+/-2.8 mm (SD) and 24.2+/-2.7 mm, respectively. Bias and precision were 1.1 mm and 1.4 mm (95% confidence interval: -1.9 to 3.7), respectively. During the course of dobutamine infusion, we observed a significant increase of TD-CO mean value from 6.65+/-1.53 L/min to 9.30+/-2.5 L/min (p=.0008), and a parallel and significant increase in ABF mean value from 4.34+/-1.18 L/min to 5.70+/-1.63 L/min (p= .0029). Absolute TD-CO and ABF values had a correlation coefficient of 0.80. For detection of an increased TD-CO, PPV and NPV were 87% and 86%, respectively. For detection of TD-CO changes >13%, PPV and NPV were 80% and 94%, respectively. CONCLUSIONS: The Dynemo-3000 system is able to display the real aortic diameter, which is one of the most important components of this noninvasive ultrasonic technique. When compared with TD-CO, the ABF determination provided by this ultrasonic device constitutes a reliable noninvasive tool for estimating CO and tracking its changes.
OBJECTIVE: The Sometec Dynemo-3000 system allows the permanent measurement of descending aorta diameter by an echographic (A-scan) device and the blood flow velocity by a pulse Doppler velocimeter. The Dynemo-3000 then furnishes a new hemodynamic parameter, i.e., descending aortic blood flow (ABF), which is a fraction of the cardiac output (CO). We evaluate the ability of this system to measure the aortic diameter and to accurately detect ABF changes. DESIGN: A case study prospective trial. SETTING: A 24-bed medical intensive care unit of a 1,100-bed university hospital. PATIENTS: Twenty critically ill patients fully sedated, mechanically ventilated, and monitored by a pulmonary artery catheter. INTERVENTIONS: CO values determined by conventional thermodilution method (TD-CO) and ABF were recorded during the study, which included two initial baseline periods, a dobutamine infusion (5 microg/kg/min) interval of 30 mins, and a third baseline period. To assess the accuracy of A-scan, aortic diameter was measured by transesophageal echocardiography. The difference between echocardiography and A-scan was used to determine bias and precision for aortic diameter measurements. TD-CO and ABF variations were analyzed using Kruskal-Wallis and Wilcoxon tests. Association between TD-CO and ABF values was determined by calculating the linear correlation coefficient. The ability of ABF to detect a TD-CO >6.0 L/min and its variations >13% was analyzed by determination of sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values. MEASUREMENTS AND MAIN RESULTS: Aortic diameter measurements by A-scan and bidimensional methods were 23.0+/-2.8 mm (SD) and 24.2+/-2.7 mm, respectively. Bias and precision were 1.1 mm and 1.4 mm (95% confidence interval: -1.9 to 3.7), respectively. During the course of dobutamine infusion, we observed a significant increase of TD-CO mean value from 6.65+/-1.53 L/min to 9.30+/-2.5 L/min (p=.0008), and a parallel and significant increase in ABF mean value from 4.34+/-1.18 L/min to 5.70+/-1.63 L/min (p= .0029). Absolute TD-CO and ABF values had a correlation coefficient of 0.80. For detection of an increased TD-CO, PPV and NPV were 87% and 86%, respectively. For detection of TD-CO changes >13%, PPV and NPV were 80% and 94%, respectively. CONCLUSIONS: The Dynemo-3000 system is able to display the real aortic diameter, which is one of the most important components of this noninvasive ultrasonic technique. When compared with TD-CO, the ABF determination provided by this ultrasonic device constitutes a reliable noninvasive tool for estimating CO and tracking its changes.
Authors: Margareta Roeck; Stephan M Jakob; Thomas Boehlen; Lukas Brander; Rafael Knuesel; Jukka Takala Journal: Intensive Care Med Date: 2003-04-09 Impact factor: 17.440
Authors: Xavier Monnet; Mario Rienzo; David Osman; Nadia Anguel; Christian Richard; Michael R Pinsky; Jean-Louis Teboul Journal: Intensive Care Med Date: 2005-07-30 Impact factor: 17.440
Authors: A Lafanechère; F Pène; C Goulenok; A Delahaye; V Mallet; G Choukroun; J D Chiche; J P Mira; A Cariou Journal: Crit Care Date: 2006 Impact factor: 9.097