scholarly journals Carbon dioxide pressure-concentration relationship in arterial and mixed venous blood during exercise

2001 ◽  
Vol 90 (5) ◽  
pp. 1798-1810 ◽  
Author(s):  
Xing-Guo Sun ◽  
James E. Hansen ◽  
William W. Stringer ◽  
Hua Ting ◽  
Karlman Wasserman
Keyword(s):  
Venous Blood ◽  
Mixed Venous Blood ◽  
Oxyhemoglobin Saturation ◽  
Fick Principle ◽  
Arterial Blood ◽  
Buffer Base ◽  
Pressure Concentration ◽  
Carbon Dioxide Pressure ◽  
Lactic Acidosis Threshold ◽  
Mixed Venous

To calculate cardiac output by the indirect Fick principle, CO2 concentrations (Cco 2) of mixed venous (Cv̄CO2 ) and arterial blood are commonly estimated from Pco 2, based on the assumption that the CO2 pressure-concentration relationship (Pco 2-Cco 2) is influenced more by changes in Hb concentration and blood oxyhemoglobin saturation than by changes in pH. The purpose of the study was to measure and assess the relative importance of these variables, both in arterial and mixed venous blood, during rest and increasing levels of exercise to maximum (Max) in five healthy men. Although the mean mixed venous Pco 2 rose from 47 Torr at rest to 59 Torr at the lactic acidosis threshold (LAT) and further to 78 Torr at Max, the Cv̄CO2 rose from 22.8 mM at rest to 25.5 mM at LAT but then fell to 23.9 mM at Max. Meanwhile, the mixed venous pH fell from 7.36 at rest to 7.30 at LAT and to 7.13 at Max. Thus, as work rate increases above the LAT , changes in pH, reflecting changes in buffer base, account for the major changes in the Pco 2-Cco 2relationship, causing Cv̄CO2 to decrease, despite increasing mixed venous Pco 2. Furthermore, whereas the increase in the arteriovenous Cco 2 difference of 2.2 mM below LAT is mainly due to the increase in Cv̄CO2 , the further increase in the arteriovenous Cco 2 difference of 4.6 mM above LAT is due to a striking fall in arterial Cco 2 from 21.4 to 15.2 mM. We conclude that changes in buffer base and pH dominate the Pco 2-Cco 2 relationship during exercise, with changes in Hb and blood oxyhemoglobin saturation exerting much less influence.

Respiratory measurements of cardiac output: from elegant idea to useful test

2004 ◽  
Vol 96 (2) ◽  
pp. 428-437 ◽  
Author(s):  
Gabriel Laszlo
Keyword(s):  
Cardiac Output ◽  
Human Subjects ◽  
Venous Blood ◽  
The Body ◽  
Mixed Venous Blood ◽  
Indirect Determination ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Pulmonary Arterial ◽  
Mixed Venous

The measurement of cardiac output was first proposed by Fick, who published his equation in 1870. Fick's calculation called for the measurement of the contents of oxygen or CO2 in pulmonary arterial and systemic arterial blood. These values could not be determined directly in human subjects until the acceptance of cardiac catheterization as a clinical procedure in 1940. In the meanwhile, several attempts were made to perfect respiratory methods for the indirect determination of blood-gas contents by respiratory techniques that yielded estimates of the mixed venous and pulmonary capillary gas pressures. The immediate uptake of nonresident gases can be used in a similar way to calculate cardiac output, with the added advantage that they are absent from the mixed venous blood. The fact that these procedures are safe and relatively nonintrusive makes them attractive to physiologists, pharmacologists, and sports scientists as well as to clinicians concerned with the physiopathology of the heart and lung. This paper outlines the development of these techniques, with a discussion of some of the ways in which they stimulated research into the transport of gases in the body through the alveolar membrane.

Lactate, pyruvate, glucose, and free fatty acid in mixed venous and arterial blood

1963 ◽  
Vol 18 (5) ◽  
pp. 933-936 ◽  
Author(s):  
P. Harris ◽  
T. Bailey ◽  
M. Bateman ◽  
M. G. Fitzgerald ◽  
J. Gloster ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Cardiac Output ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Venous Blood ◽  
Average Concentration ◽  
Mixed Venous Blood ◽  
Arterial Blood ◽  
Acquired Heart Disease ◽  
Mixed Venous

The concentrations of lactic acid, pyruvic acid, glucose, and free fatty acids have been measured simultaneously in the blood from the pulmonary and brachial arteries at rest and during exercise in a group of patients with acquired heart disease. The arteriovenous differences in the concentration of lactate, pyruvate, and free fatty acid were such as could be attributed to chance. The average concentration of glucose was slightly but significantly higher in the brachial arterial blood than in the mixed venous blood. cardiac output; lung metabolism; exercise Submitted on January 15, 1963

Evidence that the Pco2 of mixed venous blood is not a regulator of ventilation during exercise

1963 ◽  
Vol 18 (2) ◽  
pp. 345-348 ◽  
Author(s):  
Winnifred F. Storey ◽  
John Butler
Keyword(s):  
Venous Blood ◽  
Muscular Exercise ◽  
Mixed Venous Blood ◽  
Arterial Blood ◽  
Cardiac Lesions ◽  
Pulmonary Arterial ◽  
Mixed Venous

We studied 10 patients with intracardiac left-to-right shunt and 13 patients with other cardiac lesions during exercise. The hyperpnea of muscular exercise was independent of the mixed venous Pco2. In the 13 patients without shunt both the pulmonary arterial Pco2 and the ventilation increased during exercise. In the 10 patients who had shunts ventilation increased during exercise even when the Pco2 in the pulmonary arterial blood did not rise. Submitted on July 5, 1962

Changes in blood gases and acid-base balance in the exercising dog

1962 ◽  
Vol 17 (4) ◽  
pp. 656-660 ◽  
Author(s):  
Ronald L. Wathen ◽  
Howard H. Rostorfer ◽  
Sid Robinson ◽  
Jerry L. Newton ◽  
Michael D. Bailie
Keyword(s):  
Venous Blood ◽  
Blood Gases ◽  
Respiratory Alkalosis ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Mixed Venous Blood ◽  
Acid Base Balance ◽  
Hydrogen Ion Concentration ◽  
Arterial Blood ◽  
Mixed Venous

Effects of varying rates of treadmill work on blood gases and hydrogen ion concentrations of four healthy young dogs were determined by analyses of blood for O2 and CO2 contents, Po2, Pco2, and pH. Changes in these parameters were also observed during 30-min recovery periods from hard work. Arterial and mixed venous blood samples were obtained simultaneously during work through a polyethylene catheter in the right ventricle and an indwelling needle in an exteriorized carotid artery. Mixed venous O2 content, Po2 and O2 saturation fell with increased work, whereas arterial values showed little or no change. Mixed venous CO2 content, Pco2, and hydrogen ion concentration exhibited little change from resting levels in two dogs but increased significantly in two others during exercise. These values always decreased in the arterial blood during exercise, indicating the presence of respiratory alkalosis. On cessation of exercise, hyperventilation increased the degree of respiratory alkalosis, causing it to be reflected on the venous side of the circulation. Submitted on January 8, 1962

NaHCO3 does not affect arterial O2 tension but attenuates desaturation of hemoglobin in maximally exercising Thoroughbreds

2004 ◽  
Vol 96 (4) ◽  
pp. 1349-1356 ◽  
Author(s):  
Murli Manohar ◽  
Thomas E. Goetz ◽  
Aslam S. Hassan
Keyword(s):  
Maximal Exercise ◽  
Venous Blood ◽  
Pulmonary Hemorrhage ◽  
Physiological Saline ◽  
Mixed Venous Blood ◽  
Maximal Heart Rate ◽  
Arterial Hypoxemia ◽  
Arterial Blood ◽  
Exercise Induced ◽  
Mixed Venous

The objective of the present study was to examine the effects of preexercise NaHCO3 administration to induce metabolic alkalosis on the arterial oxygenation in racehorses performing maximal exercise. Two sets of experiments, intravenous physiological saline and NaHCO3 (250 mg/kg iv), were carried out on 13 healthy, sound Thoroughbred horses in random order, 7 days apart. Blood-gas variables were examined at rest and during incremental exercise, leading to 120 s of galloping at 14 m/s on a 3.5% uphill grade, which elicited maximal heart rate and induced pulmonary hemorrhage in all horses in both treatments. NaHCO3 administration caused alkalosis and hemodilution in standing horses, but arterial O2 tension and hemoglobin-O2 saturation were unaffected. Thus NaHCO3 administration caused a reduction in arterial O2 content at rest, although the arterial-to-mixed venous blood O2 content gradient was unaffected. During maximal exercise in both treatments, arterial hypoxemia, desaturation, hypercapnia, acidosis, hyperthermia, and hemoconcentration developed. Although the extent of exercise-induced arterial hypoxemia was similar, there was an attenuation of the desaturation of arterial hemoglobin in the NaHCO3-treated horses, which had higher arterial pH. Despite these observations, the arterial blood O2 content of exercising horses was less in the NaHCO3 experiments because of the hemodilution, and an attenuation of the exercise-induced expansion of the arterial-to-mixed venous blood O2 content gradient was observed. It was concluded that preexercise NaHCO3 administration does not affect the development and/or severity of arterial hypoxemia in Thoroughbreds performing short-term, high-intensity exercise.

Pulmonary vasoconstrictor response to acute decrease in blood P50

1984 ◽  
Vol 56 (2) ◽  
pp. 370-374 ◽  
Author(s):  
B. P. Teisseire ◽  
C. D. Soulard
Keyword(s):  
Right Ventricular ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Venous Blood ◽  
Systolic Pressure ◽  
Mixed Venous Blood ◽  
Right Ventricular Systolic Pressure ◽  
Ventricular Systolic Pressure ◽  
Arterial Blood ◽  
Alveolar Hypoxia ◽  
Mixed Venous

The O2 sensor that triggers hypoxic pulmonary vasoconstriction may be sensitive not only to alveolar hypoxia but also to hypoxia in mixed venous blood. A specific test of the blood contribution would be to lower mixed venous PO2 (PvO2), which can be accomplished by increasing hemoglobin-O2 affinity. When we exchanged transfused rats with cyanate-treated erythrocytes [PO2 at 50% hemoglobin saturation (P50) = 21 Torr] or with Creteil erythrocytes (P50 = 13.1 Torr), we lowered PvO2 from 39 +/- 5 to 25 +/- 4 and to 14 +/- 4 Torr, respectively, without altering arterial blood gases or hemoglobin concentration. Right ventricular systolic pressure increased from 32 +/- 2 to 36 +/- 3 Torr with cyanate erythrocytes and to 44 +/- 5 Torr with Creteil erythrocytes. Cardiac output was unchanged. Control exchange transfusions with normal rat or 2,3-diphosphoglycerate-enriched human erythrocytes had no effect on PvO2 or right ventricular pressure. Alveolar hypoxia plus high O2 affinity blood caused a greater increase in right ventricular systolic pressure than either stimulus alone. We concluded that PvO2 is an important determinant of pulmonary vascular tone in the rat.

The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass

Perfusion ◽  
2019 ◽  
Vol 34 (5) ◽  
pp. 392-398 ◽  
Author(s):  
R Peter Alston ◽  
Michael Connelly ◽  
Christopher MacKenzie ◽  
George Just ◽  
Natalie Homer
Keyword(s):  
Cardiopulmonary Bypass ◽  
Bispectral Index ◽  
Venous Blood ◽  
Index Score ◽  
Mixed Venous Blood ◽  
Depth Of Anaesthesia ◽  
Isoflurane Concentration ◽  
Time Points ◽  
Arterial Blood ◽  
Mixed Venous

Background:Administering isoflurane 2.5% into the oxygenator during cardiopulmonary bypass results in no patient movement. However, doing so may result in an excessive depth of anaesthesia particularly, when hypothermia is induced. Bispectral index and arterial blood and oxygenator exhaust concentrations of volatile anaesthetics should be related to depth of anaesthesia. The primary aim of this study was to measure the depth of anaesthesia using bispectral index, resulting from administering isoflurane 2.5% into the oxygenator during cardiopulmonary bypass, and secondary aims were to examine the relationships between blood and oxygenator exhaust isoflurane concentrations and bispectral index.Methods:Arterial and mixed-venous blood samples were aspirated at three time points during cardiopulmonary bypass and measured for isoflurane concentration using mass spectrometry. Simultaneously, oxygenator exhaust isoflurane concentration, nasopharyngeal temperature and bispectral index were recorded.Results:When averaged across the three time points, all patients had a bispectral index score below 40 (binomial test, p < 0.001). There were no significant correlations between bispectral index score and arterial or mixed-venous blood isoflurane concentrations (r = –0.082, p = 0.715; r = –0.036, p = 0.874) and oxygenator exhaust gas concentration of isoflurane (r = –0.369, p = 0.091).Conclusion:When 2.5% isoflurane was administered into the sweep gas supply to the oxygenator during cardiopulmonary bypass, all patients experienced a bispectral index score less than 40 and no significant relationship was found between either arterial or mixed-venous blood or oxygenator exhaust concentrations of isoflurane and bispectral index.

Physiological evidence for the occurrence of pathways shunting blood away from the secondary lamellae of eel gills

1982 ◽  
Vol 98 (1) ◽  
pp. 277-288
Author(s):  
G. M. Hughes ◽  
C. Peyraud ◽  
M. Peyraud-Waitzenegger ◽  
P. Soulier
Keyword(s):  
Cardiac Output ◽  
Venous Blood ◽  
Mixed Venous Blood ◽  
Intravenous Injections ◽  
Fick Principle ◽  
Secondary Lamellae ◽  
Circulatory Change ◽  
Before And After ◽  
Gill Filaments ◽  
Mixed Venous

1. Several cardiovascular and respiratory measurements have been performed in eels before and after intravenous injections of adrenaline. These experiments have allowed a comparison to be made of values for the cardiac output determined directly (Q) and using the Fick principle (QF) on individual fish under these two conditions. 2. Under control conditions it was shown that QF/Q = 0.72, indicating that about 30% of the mixed venous blood afferent to the gills is returned directly to the heart and bypasses the lamellar circulation via veno-venous anastomoses between the afferent filament arteries and the central venous space of the gill filaments. 3. Adrenaline, which during winter only has its action due to stimulation of alpha-adrenoreceptors, induced a hypoventilation but no changes in cardiac output in spite of a bradycardia. The oxygen content of the mixed venous blood was markedly increased whereas Ca,O2 remained unchanged as did the percentage utilization of oxygen from the water as it passed over the gills. The efferent blood flow from the gills after injection of adrenaline was almost equal to the total cardiac output. It is suggested that such a circulatory change was due to adrenaline-mediated constriction of veno-venous anastomoses in the gills of the eel.

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