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Transesophageal Doppler to Evaluate Aortic Blood Flow
2 Stead ww. Tuberculosis among elderly persons: an outbreak in a nursing home. Ann Intern Med 1981; 94:606-10 3 Narain J~ Lofgren J~ Warren E, Stead ww. Epidemic Tuberculosis in a nursing home: a retrospective cohort study J Am Geriatr Soc 1985;33:258-63 4 Stead ~ To T. The significance of the tuberculin skin test in elderly persons. Ann Intern Med 1987; 107:837-42 5 Ad Hoc Committee of the Scientific Assembly on TB. The tuberculin skin test. Am Rev Respir Dis 1981; 124:356-63
Transe.ophageal Doppler to Evaluate Aortic Blood Flow 7b the Editor: As an alternative method of cardiacoutput determination (rather than thermodilution, as suggested by Dr. Bobin'), we would like to
report our experience with transesophageal Doppler aortic blood flow measurement when taking the patient off cardiopulmonary bypass (CPB). Aortic blood 80w can be determined with an intra-esophageal probe with Doppler and echographic transducers.Y The juxtaposition of the aorta and the esophagus allows good ultrasonographic access to the descending aorta (Fig 1). Aortic blood velocity is measured by continuous wave Doppler (5 MHz) and aortic diameter by A-mode pulse echocardiography. An output calculator then determines the descending aortic blood 80w according to the formula Q = 5 x ~ where Q is aortic blood output, 5 is the crosssectional area of the aortic lumen (calculated from aortic diameter) and V is the average blood velocity in the aorta." Before starting CPB, the probe is gently introduced into the esophagus by nasal or oral route. The probe is first rotated to get the optimal level of Doppler signal. The A scan ensures 6ne orientation of the probe and systolic aortic diameter measurement. Aortic blood 80w can then be calculated and monitored continuously During cardiac assistance and rewarming, the probe is repositioned. Pump 80w rates are progessively decreased, taking into account arterial blood pressure (BP), left atrial pressure (LAP) and Doppler aortic blood
Table 1
EndofCPB 5 min later
DA(Umin)
LAP(cm H.O)
BP(mm Hg)
2.48±.82
5.3±3.1 10.5 ± 2.5
70±13.2 74.8 ± 9.8
3.34 ± .47
DA = Doppler aortic blood 8ow; LAP = left atrial pressure; BP =mean arterial blood pressure (m ± sd) 80w (DA). When CPB is stopped, loading conditions are managed ~o maximize aortic blood 80w The results of this technique, applied m 20 adult cardiac surgical patients, are presented in Table 1. At the end of CPB, average DA and BP of all patients increase while LAP rises during volume loading. However, two cases of cardiac failure are noted. In one case, during volume loading DA and BP decreased while LAP increased. Cardiac assistance was then continued and weaning from CPB became easy 30 min later. In another case, LAP was high at the end ofCPB and an improvement in. DA was obtained with the help of a vasodilator drug (nitroglycerme). Thermodilution cardiac output determinations are periodic and time-consuming, which is inadequate for short and rapidly evolutive hemodynamic situations. Doppler aortic blood flow provides noninvasive continuous and instantaneous monitoring. Accuracy of the Doppler determination of aortic blood 80w has been demonstrated,1-4 but a certain degree of error exists which originates from aortic diameter and blood velocity measurements, and from instability of the position of the probe." Nevertheless, the shift:of aortic blood 80w is obviously correlated to the evolution of cardiacoutput during short periods. In conclusion, Doppler aortic blood 80w measurements are particularly useful when coming off CPB.
lb8calColson, M.D.; jacques Seguin, M. D.; Bernard Roquefeuil, M.D., and lbul-Andre Chaptal, M.D. DepartmentsofAnesthesiology and CardiovascularSurgery, St Eloi Hospital, MontpeUier, France
probe position
REFERENCES
p---------
ultrasaic transducers
1 Robin ED. Death by pulmonary artery 80w directed catheter. Chest 1987; 92:727-31 2 Fourcade C, Cathignol D, Muchada R, Chapelon JY, Bui-Xuan B, Bouletreau ~ Motin J. Validation of the aortic blood 80w meter by esophageal ultrasound transducer in bloodless hemodynamic monitoring. Agressologie 1980; 21C:121-28 3 Freund PR. Transesophageal Doppler scanning versus thermodilution during general anesthesia. An initial comparison of cardiac output techniques. Am J Surg 1987; 153:490-94 4 Huntsman LL, Stewart DK, Barnes SR, Franklin SB, Clocousis JS, Hessel EA. Noninvasive Doppler determination of cardiac output in man. Clinical validation. Circulation 1983; 67:593-601
Erratum A:ECHO
CDtic diameter
B:DOPPLER
Doppler wave
F~GURE 1.. Position of the probe; echo and Doppler signals. Aortic diameter IS measured from the position of two cursors which are manually moved under the aortic walls echocardiographic signals.
882
7b the Editor: I note that the printed text of our article on the optimal therapeutic range for warfarin has an error in the calculation of INR on page 65, line 15 of the Chest supplement (February, 1989). The "c" that follows the prothrombin time ratio should have been a superscript indicating that the ratio is raised to the power. This is crucial to understanding the INR. Daniel Deykin, M. D.
Boston
Communications to the Eeltor'
Transe.ophageal Doppler to Evaluate Aortic Blood Flow 7b the Editor: As an alternative method of cardiacoutput determination (rather than thermodilution, as suggested by Dr. Bobin'), we would like to
report our experience with transesophageal Doppler aortic blood flow measurement when taking the patient off cardiopulmonary bypass (CPB). Aortic blood 80w can be determined with an intra-esophageal probe with Doppler and echographic transducers.Y The juxtaposition of the aorta and the esophagus allows good ultrasonographic access to the descending aorta (Fig 1). Aortic blood velocity is measured by continuous wave Doppler (5 MHz) and aortic diameter by A-mode pulse echocardiography. An output calculator then determines the descending aortic blood 80w according to the formula Q = 5 x ~ where Q is aortic blood output, 5 is the crosssectional area of the aortic lumen (calculated from aortic diameter) and V is the average blood velocity in the aorta." Before starting CPB, the probe is gently introduced into the esophagus by nasal or oral route. The probe is first rotated to get the optimal level of Doppler signal. The A scan ensures 6ne orientation of the probe and systolic aortic diameter measurement. Aortic blood 80w can then be calculated and monitored continuously During cardiac assistance and rewarming, the probe is repositioned. Pump 80w rates are progessively decreased, taking into account arterial blood pressure (BP), left atrial pressure (LAP) and Doppler aortic blood
Table 1
EndofCPB 5 min later
DA(Umin)
LAP(cm H.O)
BP(mm Hg)
2.48±.82
5.3±3.1 10.5 ± 2.5
70±13.2 74.8 ± 9.8
3.34 ± .47
DA = Doppler aortic blood 8ow; LAP = left atrial pressure; BP =mean arterial blood pressure (m ± sd) 80w (DA). When CPB is stopped, loading conditions are managed ~o maximize aortic blood 80w The results of this technique, applied m 20 adult cardiac surgical patients, are presented in Table 1. At the end of CPB, average DA and BP of all patients increase while LAP rises during volume loading. However, two cases of cardiac failure are noted. In one case, during volume loading DA and BP decreased while LAP increased. Cardiac assistance was then continued and weaning from CPB became easy 30 min later. In another case, LAP was high at the end ofCPB and an improvement in. DA was obtained with the help of a vasodilator drug (nitroglycerme). Thermodilution cardiac output determinations are periodic and time-consuming, which is inadequate for short and rapidly evolutive hemodynamic situations. Doppler aortic blood flow provides noninvasive continuous and instantaneous monitoring. Accuracy of the Doppler determination of aortic blood 80w has been demonstrated,1-4 but a certain degree of error exists which originates from aortic diameter and blood velocity measurements, and from instability of the position of the probe." Nevertheless, the shift:of aortic blood 80w is obviously correlated to the evolution of cardiacoutput during short periods. In conclusion, Doppler aortic blood 80w measurements are particularly useful when coming off CPB.
lb8calColson, M.D.; jacques Seguin, M. D.; Bernard Roquefeuil, M.D., and lbul-Andre Chaptal, M.D. DepartmentsofAnesthesiology and CardiovascularSurgery, St Eloi Hospital, MontpeUier, France
probe position
REFERENCES
p---------
ultrasaic transducers
1 Robin ED. Death by pulmonary artery 80w directed catheter. Chest 1987; 92:727-31 2 Fourcade C, Cathignol D, Muchada R, Chapelon JY, Bui-Xuan B, Bouletreau ~ Motin J. Validation of the aortic blood 80w meter by esophageal ultrasound transducer in bloodless hemodynamic monitoring. Agressologie 1980; 21C:121-28 3 Freund PR. Transesophageal Doppler scanning versus thermodilution during general anesthesia. An initial comparison of cardiac output techniques. Am J Surg 1987; 153:490-94 4 Huntsman LL, Stewart DK, Barnes SR, Franklin SB, Clocousis JS, Hessel EA. Noninvasive Doppler determination of cardiac output in man. Clinical validation. Circulation 1983; 67:593-601
Erratum A:ECHO
CDtic diameter
B:DOPPLER
Doppler wave
F~GURE 1.. Position of the probe; echo and Doppler signals. Aortic diameter IS measured from the position of two cursors which are manually moved under the aortic walls echocardiographic signals.
882
7b the Editor: I note that the printed text of our article on the optimal therapeutic range for warfarin has an error in the calculation of INR on page 65, line 15 of the Chest supplement (February, 1989). The "c" that follows the prothrombin time ratio should have been a superscript indicating that the ratio is raised to the power. This is crucial to understanding the INR. Daniel Deykin, M. D.
Boston
Communications to the Eeltor'