Physiological parameters of indicator dilution curves

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.

A small, lightweight precordial counter for determination of cardiac output

1965 ◽  
Vol 20 (6) ◽  
pp. 1365-1366 ◽  
Author(s):  
Ralph J. Gorten
Keyword(s):  
Cardiac Output ◽  
Scintillation Detector ◽  
Treadmill Exercise ◽  
Bicycle Ergometer ◽  
Indicator Dilution ◽  
Energy Gamma ◽  
Lead Shielding ◽  
Thin Crystal ◽  
Dilution Curves

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

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

1964 ◽  
Vol 19 (5) ◽  
pp. 1024-1027 ◽  
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

scholarly journals Exchange of potassium and strontium in adult bone

1982 ◽  
Vol 242 (4) ◽  
pp. H705-H712 ◽  
Author(s):  
B. Maltby ◽  
G. J. Lemon ◽  
J. B. Bassingthwaighte ◽  
P. J. Kelly
Keyword(s):  
Cortical Bone ◽  
Time Course ◽  
Volume Of Distribution ◽  
Indicator Dilution ◽  
Adsorption Sites ◽  
Nutrient Artery ◽  
Extravascular Volume ◽  
Kinetics Of ◽  
Adult Bone ◽  
Dilution Curves

The kinetics of exchange of strontium (85Sr) and potassium (42K) were studied in the mid-tibial cortical bone of 37 adult dogs. After injection of these two tracer cations and tracer-labeled albumin into the tibial nutrient artery, two types of observations were made: 1) collection of sequential venous samples to provide the outflow indicator-dilution curves and to calculate the extraction and retention at early times; and 2) detection of energy-selected gamma emissions via a detector over the tibia to give the time course of content of 42K and 85Sr in the tibia. Extractions of K+ and Sr2+ were 50 and 60% during a single transcapillary passage. More Sr2+ than K+ was retained in the first minutes. Their rates of washout over a 3-h period were similar. The interpretation is that the rate of uptake at extravascular sites is faster for Sr2+ than for K+, as is the rate of release, and that the extravascular volume of distribution for Sr2+ (adsorption sites in the interstitium or on bone) is much larger than that for K+ (intracellular).

Estimates of cardiac output from forward part of indicator dilution curves

1961 ◽  
Vol 16 (5) ◽  
pp. 891-895 ◽  
Author(s):  
Geoffrey D. Thorburn
Keyword(s):  
Cardiac Output ◽  
Injection Site ◽  
Path Length ◽  
Indicator Dilution ◽  
New Method ◽  
Flow Volume ◽  
Initial Part ◽  
Dye Dilution ◽  
Forward Part ◽  
Dilution Curves

A study was made of 135 dye-dilution curves, 77 of which were obtained from dogs and 58 from man. It was previously shown that the degree of asymmetry of indicator dilution curves varies with changes in flow, volume, and path length, and this has been found to influence the estimates of cardiac output made from the initial part of the curves by the forward triangle and Dow methods, and by a new method described in this paper. This variation may be minimized by the calculation of separate constants for each injection site and by keeping the variation in flow and volume as small as possible. Errors are likely to arise when these methods are used outside the range of the normal data. It has been found that this variation in asymmetry is mainly responsible for the scatter in the estimates of cardiac output using these methods. The agreement between the forward triangle and the Dow methods was found to be very close and the reason for this is discussed. Submitted on February 13, 1961

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