Cardiac output measurements using sonomicrometer crystals on the left ventricle at rest and exercise

Abstract Background Critical care ultrasonography (CCUS) is increasingly applied also in the intensive care unit (ICU) and performed by non-experts, including even medical students. There is limited data on the training efforts necessary for novices to attain images of sufficient quality. There is no data on medical students performing CCUS for the measurement of cardiac output (CO), a hemodynamic variable of importance for daily critical care. Objective The aim of this study was to explore the agreement of cardiac output measurements as well as the quality of images obtained by medical students in critically ill patients compared to the measurements obtained by experts in these images. Methods In a prospective observational cohort study, all acutely admitted adults with an expected ICU stay over 24 h were included. CCUS was performed by students within 24 h of admission. CCUS included the images required to measure the CO, i.e., the left ventricular outflow tract (LVOT) diameter and the velocity time integral (VTI) in the LVOT. Echocardiography experts were involved in the evaluation of the quality of images obtained and the quality of the CO measurements. Results There was an opportunity for a CCUS attempt in 1155 of the 1212 eligible patients (95%) and in 1075 of the 1212 patients (89%) CCUS examination was performed by medical students. In 871 out of 1075 patients (81%) medical students measured CO. Experts measured CO in 783 patients (73%). In 760 patients (71%) CO was measured by both which allowed for comparison; bias of CO was 0.0 L min−1 with limits of agreement of − 2.6 L min−1 to 2.7 L min−1. The percentage error was 50%, reflecting poor agreement of the CO measurement by students compared with the experts CO measurement. Conclusions Medical students seem capable of obtaining sufficient quality CCUS images for CO measurement in the majority of critically ill patients. Measurements of CO by medical students, however, had poor agreement with expert measurements. Experts remain indispensable for reliable CO measurements. Trial registration Clinicaltrials.gov; http://www.clinicaltrials.gov; registration number NCT02912624

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Upright Cardiac Output Measurements in the Transition to Weightlessness During Parabolic Flights

Aviation Space and Environmental Medicine ◽

10.3357/asem.2883.2011 ◽

2011 ◽

Vol 82 (4) ◽

pp. 448-454 ◽

Cited By ~ 8

Author(s):

Ulrich Limper ◽

Peter Gauger ◽

Luis E. J. Beck

Keyword(s):

Cardiac Output ◽

Parabolic Flights ◽

Cardiac Output Measurements

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Correlation of Carotid Blood Flow and Carotid Flow Time With Invasive Cardiac Output Measurements

CHEST Journal ◽

10.1016/j.chest.2016.08.310 ◽

2016 ◽

Vol 150 (4) ◽

pp. 297A

Author(s):

Irene Ma ◽

Joshua Caplin ◽

Aftab Azad ◽

Christina Wilson ◽

Michael Fifer ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Flow Time ◽

Carotid Blood Flow ◽

Cardiac Output Measurements ◽

Carotid Flow

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MECHANISMS OF ADAPTATION OF THE LEFT VENTRICLE TO MUSCULAR EXERCISE

PEDIATRICS ◽

10.1542/peds.32.4.660 ◽

1963 ◽

Vol 32 (4) ◽

pp. 660-670

Author(s):

Jere H. Mitchell

Keyword(s):

Cardiac Output ◽

Left Ventricle ◽

Stroke Volume ◽

Pulse Rate ◽

Individual Factors ◽

Normal Male ◽

Oxygen Intake ◽

Mechanisms Of Adaptation ◽

Male Subjects ◽

Oxygen Difference

THE mechanisms of adaptation of the left ventricle to the demands of muscular exercise have intrigued cardiovascular physiologists for many years. Although highly complex, these adaptive mechanisms are more and more susceptible to analysis and quantification. In this presentation I will attempt to identify some of the individual factors which appear to be important in the response of the left ventricle to exercise, beginning with data obtained from experiments on conscious normal male subjects and proceeding to experiments performed on dog preparations in which individual factors were controlled and analyzed. The changes in oxygen intake, cardiac output, estimated arteriovenous oxygen difference, pulse rate and estimated mean stroke volume were determined in 15 normal male subjects during rest in the standing position and during treadmill exercise at the maximal oxygen intake level. Oxygen intake was obtained from the volume and composition of expired air, cardiac output by the dye dilution technique, and pulse rate from the electrocardiogram. Estimated arteriovenous oxygen difference was obtained by dividing the oxygen intake by the cardiac output (Fick principle) and estimated mean stroke volume by dividing the cardiac output by the heart rate. The data are shown in Figure 1. Oxygen intake increased from a mean value of 0.34 at rest to a maximal value of 3.22 L./min. The corresponding mean values for cardiac output were 5.4 and 23.4 L./min. and for arteriovenous oxygen difference were 6.5 and 14.3 ml./100 ml. Thus, as oxygen intake increased 9.5 times, the cardiac output increased 4.3 times and the arterio venous oxygen difference 2.2 times.

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Comparison of cardiac output measurements using electrical velocimetry and lithium dilution with thermodilution in anesthetized dogs

Veterinary Anaesthesia and Analgesia ◽

10.1016/j.vaa.2021.08.035 ◽

2021 ◽

Vol 48 (6) ◽

pp. S997

Author(s):

V. Paranjape ◽

N. Henao-Guerrero ◽

G. Menciotti ◽

F. Garcia-Pereira ◽

C. Ricco-Pereira

Keyword(s):

Cardiac Output ◽

Electrical Velocimetry ◽

Anesthetized Dogs ◽

Cardiac Output Measurements

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Thermodilution method overestimates low cardiac output in humans

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1983.245.4.h690 ◽

1983 ◽

Vol 245 (4) ◽

pp. H690-H692 ◽

Cited By ~ 11

Author(s):

A. van Grondelle ◽

R. V. Ditchey ◽

B. M. Groves ◽

W. W. Wagner ◽

J. T. Reeves

Keyword(s):

Cardiac Output ◽

Heat Loss ◽

Low Flow ◽

Clinical Implications ◽

Low Cardiac Output ◽

Dye Dilution ◽

Thermodilution Method ◽

Cardiac Output Measurements

We compared 57 cardiac output measurements by the thermodilution and Fick methods in 26 patients and found that thermodilution values were higher in all 16 cases in which Fick outputs were less than 3.5 l/min. In 10 cases where Fick values were less than or equal to 2.5 l/min, thermodilution and Fick measurements differed by an average of 35%. When combined with the results of previous studies comparing the thermodilution, dye dilution, and Fick techniques, these findings suggest that the thermodilution method overestimates true cardiac output in the low output range. This overestimation probably is due to heat loss under conditions of low flow. Because the thermodilution method is used widely in patients with low output states, these findings have potentially important clinical implications.

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Biplane ventriculography in the rat

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1986.250.1.h131 ◽

1986 ◽

Vol 250 (1) ◽

pp. H131-H136

Author(s):

J. L. Heckman ◽

L. Garvin ◽

T. Brown ◽

W. Stevenson-Smith ◽

W. P. Santamore ◽

...

Keyword(s):

Cardiac Output ◽

Left Ventricle ◽

Ejection Fraction ◽

Stroke Volume ◽

Methyl Methacrylate ◽

High Speed ◽

Water Displacement ◽

Systolic Volume ◽

End Diastolic Volume ◽

End Systolic Volume

Biplane ventriculography was performed on nine intact anesthetized rats. Images of the left ventricle large enough for analysis were obtained by placing the rats close to the radiographic tubes (direct enlargement). Sampling rates, adequate for heart rates of 500 beats/min, were obtained by filming at 500 frames/s. From the digitized silhouettes of the left ventricle the following information was obtained (means +/- SE): end-diastolic volume 0.60 +/- 0.03 ml, end-systolic volume 0.22 +/- 0.02 ml, stroke volume 0.38 +/- 0.02 ml, ejection fraction 0.63 +/- 0.02, cardiac output 118 +/- 7 ml/min, diastolic septolateral dimension 0.41 +/- 0.01 mm, diastolic anteroposterior dimension 0.40 +/- 0.01 mm, diastolic base-to-apex dimension 1.58 +/- 0.04 mm. To determine the accuracy with which the volume of the ventricle could be measured, 11 methyl methacrylate casts of the left ventricle were made. The correlation was high (r = 0.99 +/- 0.02 ml E) between the cast volumes determined by water displacement and by use of two monoplane methods (Simpson's rule of integration and the area-length method applied to the analysis of the anteroposterior films) and a biplane method (area-length). These results demonstrate that it is possible to obtain accurate dimensions and volumes of the rat left ventricle by use of high-speed ventriculography.

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