Cardiac output and mixed venous oxygen content measurements by a tracer bolus method: theory

1997 ◽  
Vol 83 (3) ◽  
pp. 884-896 ◽  
Author(s):  
Justin S. Clark ◽  
Yuxiang J. Lin ◽  
Michael J. Criddle ◽  
Antonio G. Cutillo ◽  
Adelbert H. Bigler ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Oxygen Content ◽  
Practical Method ◽  
Parameter Extraction ◽  
Extraction Process ◽  
Inert Gases ◽  
Inert Gas ◽  
Venous Oxygen Content ◽  
Sinusoidal Input ◽  
Mixed Venous

Clark, Justin S., Yuxiang J. Lin, Michael J. Criddle, Antonio G. Cutillo, Adelbert H. Bigler, Fred L. Farr, and Attilio D. Renzetti, Jr. Cardiac output and mixed venous oxygen content measurements by a tracer bolus method: theory. J. Appl. Physiol. 83(3): 884–896, 1997.—We present a bolus method of inert-gas delivery to the lungs that facilitates application of multiple inert gases and the multiple inert-gas-exchange technique (MIGET) model to noninvasive measurements of cardiac output (CO) and central mixed venous oxygen content[Formula: see text]Reduction in recirculation error is made possible by 1) replacement of sinusoidal input functions with impulse inputs and 2) replacement of steady-state analyses with transient analyses. Recirculation error reduction increases the inert-gas selection to include common gases without unusually high (and difficult to find) tissue-to-blood partition coefficients for maximizing the systemic filtering efficiency. This paper also presents a practical method for determining the recirculation contributions to inert expired profiles in animals and determining their specific contributions to errors in the calculations of CO and[Formula: see text] from simulations applied to published ventilation-perfusion ratio (V˙/Q˙) profiles. Recirculation errors from common gases were found to be reducible to the order of 5% or less for both CO and[Formula: see text] whereas simulation studies indicate that measurement bias contributions from recirculation, V˙/Q˙ mismatch, and the V˙/Q˙ extraction process can be limited to 15% for subjects with severeV˙/Q˙ mismatch and high inspired oxygen fraction levels. These studies demonstrate a decreasing influence of V˙/Q˙ mismatch on parameter extraction bias as the number of inert gases are increased. However, the influence of measurement uncertainty on parameter extraction error limits improvement to six gases.

Oxygen Therapy Titrated to Raise Mixed Venous Oxygen Content in COPD

CHEST Journal ◽  
1986 ◽  
Vol 89 (3) ◽  
pp. 343-347 ◽  
Author(s):  
Michael L. Peil ◽  
Lewis J. Rubin
Keyword(s):  
Oxygen Content ◽  
Oxygen Therapy ◽  
Venous Oxygen Content ◽  
Mixed Venous

Estimation of ventilation-perfusion inequality by inert gas elimination without arterial sampling

1985 ◽  
Vol 59 (2) ◽  
pp. 376-383 ◽  
Author(s):  
P. D. Wagner ◽  
C. M. Smith ◽  
N. J. Davies ◽  
R. D. McEvoy ◽  
G. E. Gale
Keyword(s):  
Cardiac Output ◽  
Venous Blood ◽  
Inert Gas ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Arterial Access ◽  
Arterial Blood ◽  
Potential Applications ◽  
Clinical Interest ◽  
Mixed Venous

Estimation of ventilation-perfusion (VA/Q) inequality by the multiple inert gas elimination technique requires knowledge of arterial, mixed venous, and mixed expired concentrations of six gases. Until now, arterial concentrations have been directly measured and mixed venous levels either measured or calculated by mass balance if cardiac output was known. Because potential applications of the method involve measurements over several days, we wished to determine whether inert gas levels in peripheral venous blood ever reached those in arterial blood, thus providing an essentially noninvasive approach to measuring VA/Q mismatch that could be frequently repeated. In 10 outpatients with chronic obstructive pulmonary disease, we compared radial artery (Pa) and peripheral vein (Pven) levels of the six gases over a 90-min period of infusion of the gases into a contralateral forearm vein. We found Pven reached 90% of Pa by approximately 50 min and 95% of Pa by 90 min. More importantly, the coefficient of variation at 50 min was approximately 10% and at 90 min 5%, demonstrating acceptable intersubject agreement by 90 min. Since cardiac output is not available without arterial access, we also examined the consequences of assuming values for this variable in calculating mixed venous levels. We conclude that VA/Q features of considerable clinical interest can be reliably identified by this essentially noninvasive approach under resting conditions stable over a period of 1.5 h.

Effect of Bilateral Occlusion of Common Carotid Arteries on Cardiac Output and Oxygen Content of Arterial and Venous Blood in the Anesthetized Dog

1956 ◽  
Vol 185 (3) ◽  
pp. 483-486 ◽  
Author(s):  
Shirley H. Brind ◽  
Joseph R. Bianchine ◽  
Matthew N. Levy
Keyword(s):  
Cardiac Output ◽  
Oxygen Content ◽  
Venous Blood ◽  
Carotid Occlusion ◽  
Systemic Hypertension ◽  
Arterial Blood ◽  
Venous Oxygen Content ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Common Carotid Arteries

Changes in cardiac output, mean arterial blood pressure, hematocrit ratio, and arterial and venous oxygen content resulting from bilateral carotid occlusion were investigated. Cardiac output exhibited no significant alteration during endosinusal hypotension, and the systemic hypertension engendered was attributed to an increase in vasomotor tone. Arterial and venous oxygen content, as well as hematocrit ratio, increased significantly during the period of carotid occlusion. This increase was ascribed to splenic contraction evoked by carotid occlusion, since no comparable augmentation was observed when the splenic circulation was temporarily interrupted.

scholarly journals Venous Admixture Effect during One-lung Anaesthesia

1972 ◽  
Vol 1 (1) ◽  
pp. 45-53 ◽  
Author(s):  
T. A. Torda ◽  
H. D. O'Brien ◽  
C. McCulloch ◽  
K. Tsui
Keyword(s):  
Carbon Dioxide ◽  
Cardiac Output ◽  
Oxygen Saturation ◽  
Oxygen Content ◽  
Carbon Dioxide Tension ◽  
Venous Admixture ◽  
Content Difference ◽  
Venous Oxygen Content ◽  
The Mean

The venous admixture was measured before, during, and after deflation of one lung during anaesthesia for thoracotomy in 10 subjects ventilated with 50% oxygen. The mean oxygen saturation fell from 99% before deflation of the lung to 89% after 30 minutes’ atelectasis. The pH and carbon dioxide tension did not change significantly. The shunt was 38% of cardiac output five minutes after and 41% 30 minutes after deflation. The reciprocal of the arterial venous oxygen content difference correlated positively with the shunt, suggesting that increased venous admixture is accompanied by increased cardiac output.

Graphical analysis of multiple inert gas elimination data

1983 ◽  
Vol 55 (1) ◽  
pp. 32-36 ◽  
Author(s):  
W. E. Stewart ◽  
S. M. Mastenbrook
Keyword(s):  
Gas Exchange ◽  
Companion Paper ◽  
Graphical Analysis ◽  
Inert Gases ◽  
Inert Gas ◽  
Additional Test ◽  
Multicompartmental Model ◽  
Simple Rules ◽  
Gas Measurements ◽  
Mixed Venous

A plot of measured retention-excretion ratios [(Ri/Ei)obs] vs. reciprocal solubility (1/lambda i) for selected inert gases allows quick detection of shunt and ventilation-perfusion (V/Q) inhomogeneity in the lung. We derive simple rules for constructing a smooth R/E function from the data, using a multicompartmental model of the lung. If mixed venous inert gas measurements are available, the values [lambda i(1-Ri)/Ei]obs for the infused gases can be used to estimate the overall VT/QT ratio and provide an additional test of the consistency of the data. For any set of equilibrium compartments ventilated and perfused in parallel, we show that d(R/E)/d(1/lambda) cannot be negative, nor can d2(R/E)/d(1/lambda)2 be greater than zero. A rectilinear R/E function implies a narrow distribution of V/Q among the gas exchange compartments, whereas a downward-concave curve implies a broader distribution. The shunt perfusion and dead-space ventilation can be estimated from the asymptotes of the R/E function. The range of V/Q for the gas exchange compartments can also be bracketed if a well-defined region of curvature is present in the graph. Finally, from the R/E vs. 1/lambda graph and (if mixed venous data are available) from the lambda(1-R)/E values, we can determine quickly whether the data deserve the detailed numerical analysis outlined in our companion paper.

VARIATION SIMULATION OF RADON CONCENTRATION IN THE TISSUES AND ORGANS OF THE BODY BY AN ELECTRICAL CIRCUIT

2019 ◽  
Vol 187 (3) ◽  
pp. 390-401
Author(s):  
Milad Pirmoradi ◽  
Ali Negarestani ◽  
Amin Baghizadeh
Keyword(s):  
Cardiac Output ◽  
Human Body ◽  
Absorbed Dose ◽  
Electrical Circuit ◽  
The Body ◽  
Inert Gases ◽  
Inert Gas ◽  
Voltage Source ◽  
Red Marrow ◽  
Inhalation Rate

Abstract In this study, a new model based on electric circuit theory has been introduced to simulate the dynamics of radioactive chemically inert gases in the human body. For this manner, it is assumed that inert gas is transported through the body to various organs via the blood stream. In this simulation, a voltage source is equivalent to gas generation in the atmosphere, the conductivity is equivalent to the cardiac output of the organ, the capacitor capacitance is equivalent to the volume of blood or tissue and voltage across a capacitor is equivalent to the gas concentration in air or blood or a tissue. This simulation can be used to study the dynamics of any inert gas whose partition coefficients are known. We use this simulation to study the dynamics of radon in human body. The physiologically based pharmacokinetic (PBPK) model that describes the fate of radon in systemic tissue has been used for this simulation. Using this simulation, the effective dose equivalent resulting from inhalation of radon has been estimated. The calculated values agree with the previously reported value. Also, using the model, it has been shown that after inhalation of radon gas, absorbed dose has been decreased in different tissues by increasing the inhalation rate without radon. So that, by doubling the inhalation rate and the rate of cardiac output, the value of the absorbed dose has been decreased 11.88% in the adipose tissue, 25.49% in the red marrow tissue and 20.3% in the liver organ.

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