A small, lightweight precordial counter for determination of cardiac output

A compact, lightweight scintillation detector which can be firmly attached to the anterior chest was fabricated in order to better adapt the isotope-precordial counting technic for measurements of cardiac output during exercise. In this manner useful indicator-dilution curves can be obtained without arterial puncture at light-to-heavy levels of bicycle ergometer or treadmill exercise. The use of a thin crystal and the omission of lead shielding and collimation of the detector is possible with a soft-energy gamma-emitting indicator of blood flow such as iodinated (I125) albumin. cardiac output during exercise; lightweight precordial scintillation detector; iodione 125; isotope-precordial counting technic Submitted on May 28, 1965

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Physiological parameters of indicator dilution curves

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1977.233.3.h350 ◽

1977 ◽

Vol 233 (3) ◽

pp. H350-H355

Author(s):

L. D. Homer ◽

A. Small

Keyword(s):

Cardiac Output ◽

Satisfactory Agreement ◽

Single Injection ◽

Time Lag ◽

Volume Of Distribution ◽

Physiological Parameters ◽

Indicator Dilution ◽

Diethylenetriaminepentaacetic Acid ◽

Alternative Techniques ◽

Dilution Curves

A model incorporating the effects of recirculation time lag, cardiac output, clearance, volume of distribution, and the variance of the distribution of recirculation times is applied to the analysis of indicator dilution curves. Experiments on dogs with use of radioactively labeled diethylenetriaminepentaacetic acid were done to evaluate the model. This five-parameter model can be fitted to data obtained during the period from less than 1 min to 3 h after a single injection of indicator. Estimates of cardiac output and clearance are in satisfactory agreement with estimates obtained by alternative techniques. Estimates of the time lag and volume of distribution are of physiologically plausible magnitude. The variance of the distribution of recirculation times is a new parameter, of which the possible usefulness to physiologists is discussed.

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Detection of early central circulatory transits in patients with cirrhosis by gamma variate fit of indicator dilution profiles

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00201.2004 ◽

2005 ◽

Vol 288 (4) ◽

pp. G677-G684 ◽

Cited By ~ 7

Author(s):

Jens H. Henriksen ◽

Søren Møller ◽

Stefan Fuglsang ◽

Flemming Bendtsen

Keyword(s):

Cardiac Output ◽

Blood Volume ◽

Indicator Dilution ◽

Arterial Oxygen ◽

Dilution Method ◽

Gamma Variate ◽

Arterial Blood ◽

Flow Circulation ◽

Cirrhotic Patients

Patients with cirrhosis have hyperdynamic circulation with abnormally distributed blood volume and widespread arteriovenous communications. We aimed to detect possible very early (i.e., before 4 s) and early (i.e., after 4 s) central circulatory transits and their potential influence on determination of central and arterial blood volume (CBV). Thirty-six cirrhotic patients and nineteen controls without liver disease undergoing hemodynamic catheterization were given central bolus injections of albumin with different labels. Exponential and gamma variate fits were applied to the indicator dilution curves, and the relations between flow, circulation times, and volumes were established according to kinetic principles. No significant very early central circulatory transits were identified. In contrast, early (i.e., 4 s to maximal) transits corresponding to a mean of 5.1% (vs. 0.8% in controls; P < 0.005) of cardiac output (equivalent to 0.36 vs. 0.05 l/min; P < 0.01) were found in cirrhotic patients. These early transits averaged 7.7 vs. 12.7 and 17.2 s of ordinary central transits of cirrhotic patients and controls, respectively ( P < 0.001). Early transits were directly correlated to the alveolar-arterial oxygen difference in the cirrhotic patients ( r = 0.46, P < 0.01) but not in controls ( r = 0.04; not significant). There was good agreement between the CBV determined by the conventional indicator dilution method and that determined by separation of early and ordinary transits by the gamma variate fit method (1.51 vs. 1.53 liter; not significant). In conclusion, no very early central circulatory transits were identified in cirrhotic patients. A significant part of the cardiac output undergoes an early transit, probably through pulmonary shunts or areas with low ventilation-perfusion ratios in cirrhotic patients. Composite determination of CBV by the gamma variate fit method is in close agreement with established kinetic methods. The study provides further evidence of abnormal central circulation in cirrhosis.

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A new type of syringe holder for performance of indicator-dilution curves

Journal of Applied Physiology ◽

10.1152/jappl.1964.19.5.1022 ◽

1964 ◽

Vol 19 (5) ◽

pp. 1022-1023 ◽

Cited By ~ 2

Author(s):

Robert W. Benson ◽

L. Jerome Krovetz ◽

Gerold L. Schiebler

Keyword(s):

Precise Determination ◽

Indicator Dilution ◽

Constant Volume ◽

Dilution Curve ◽

Appearance Time ◽

Time Marker ◽

Indicator Dilution Curve ◽

New Type ◽

Dilution Curves

A new type of syringe holder, simple and rugged, has been designed to combine a constant volume syringe with an electrical time marker initiator. The latter allows a precise determination of the appearance time of an indicator-dilution curve. appearance time Submitted on March 2, 1964

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Performance of a new on-line computer for indicator-dilution curves

Journal of Applied Physiology ◽

10.1152/jappl.1964.19.5.1024 ◽

1964 ◽

Vol 19 (5) ◽

pp. 1024-1027 ◽

Cited By ~ 5

Author(s):

Hans U. Wessel ◽

Charles F. Hepner ◽

Gordon W. James ◽

Paul Kezdi

Keyword(s):

Cardiac Output ◽

Goodness Of Fit ◽

Analog Computer ◽

Indicator Dilution ◽

Stable Operation ◽

Flow Rates ◽

On Line ◽

The Mean ◽

Graphic Methods ◽

Dilution Curves

An analog computer was designed for on-line computation of the area under indicator-dilution curves. From a model circulation and from two dogs, 165 tricarbocyanine green dilution curves were recorded with a cuvette densitometer, together with the computed area and signals indicating 60% and 30% of the peak deflection on the down slope of the curve. An IBM 709 digital computer was programmed to compare automatically and conventionally computed flow rates, to analyze sources of error in the computer, and to determine the goodness of fit of the extrapolated exponentials. The results indicated stable operation of the computer. The mean difference between the computer and graphic integration was minus 1.0% ± 2.4% for 78 flow estimates in the model, and 1.9% ± 2.5% for 30 cardiac output in the dogs. Data suggest that the computer does not introduce a significant error provided the dilution curves are also suitable for established graphic methods of integration. special purpose analog computer; instrumentation; cardiac output Submitted on December 6, 1963

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