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.

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.

Influence of changes in cardiac output on the acid-base status of arterial and mixed venous blood

1987 ◽  
Vol 410 (3) ◽  
pp. 257-262 ◽  
Author(s):  
Y. L. Hoogeveen ◽  
J. P. Zock ◽  
P. Rispens ◽  
W. G. Zijlstra
Keyword(s):  
Cardiac Output ◽  
Venous Blood ◽  
Mixed Venous Blood ◽  
Acid Base ◽  
Acid Base Status ◽  
Mixed Venous

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

scholarly journals Indirect calorimetry can be used to measure cardiac output in septic patients?

2008 ◽  
Vol 23 (suppl 1) ◽  
pp. 118-125 ◽  
Author(s):  
Maria Auxiliadora Martins ◽  
Francisco Antônio Coletto ◽  
Antônio Dorival Campos ◽  
Anibal Basile-Filho
Keyword(s):  
Intensive Care Unit ◽  
Cardiac Output ◽  
Indirect Calorimetry ◽  
Venous Blood ◽  
Correlation Coefficients ◽  
University Hospital ◽  
Parallel Analysis ◽  
Monitoring Systems ◽  
Mixed Venous Blood ◽  
Mixed Venous

PURPOSE: The aim of this study was to compare two different cardiac output (CO) monitoring systems based on the thermodilution principle (Thermo-CO) and indirect calorimetry (Fick mixed-CO) in septic patients. METHODS: Prospective study in septic patients admitted in an intensive care unit of a university hospital. Nineteen patients aged on average 45.4 ± 21.5 years were enrolled in the study. Four series of hourly measurements by the two techniques were carried out simultaneously. RESULTS: No significant differences were observed between Thermo-CO and Fick mixed-CO (7.0 ± 1.8 L.min-1 and 6.4 ± 1.7 L.min-1.). Parallel analysis of Fick mixed-CO and Fick atrial-CO was performed introducing a correction factor for the eight atrial samples in order to adjust the values of oxygen saturation obtained from atrial blood (Fick corrected atrial-CO) to those obtained from mixed venous blood. No significant differences could be detected between Fick mixed-CO and Fick corrected atrial-CO. The correlation coefficients of Thermo CO/Fick mixed-CO and Fick mixed-CO/Fick corrected atrial-CO were 0.84 and 0.94, respectively. CONCLUSION: We observed that the agreement between the two methods was satisfactory on the basis of the decisions made for treatment. Indirect calorimetry is useful to measure CO in patients with septic shock.

scholarly journals YOUNG CLINICIANS’ FORUM Correlation between mixed venous blood saturation and cardiac output in patients undergoing cardiac surgery procedures

2013 ◽  
Vol 1 ◽  
pp. 79-83
Author(s):  
Bartosz Szurlej ◽  
Magda Piekarska ◽  
Dariusz Szurlej ◽  
Andrzej Węglarzy ◽  
Tomasz Latusek ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Cardiac Surgery ◽  
Venous Blood ◽  
Mixed Venous Blood ◽  
Mixed Venous

Effects of respiratory muscle work on cardiac output and its distribution during maximal exercise

1998 ◽  
Vol 85 (2) ◽  
pp. 609-618 ◽  
Author(s):  
Craig A. Harms ◽  
Thomas J. Wetter ◽  
Steven R. McClaran ◽  
David F. Pegelow ◽  
Glenn A. Nickele ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Respiratory Muscle ◽  
Maximal Exercise ◽  
Work Of Breathing ◽  
Venous Blood ◽  
Inspiratory Muscle ◽  
Mixed Venous Blood ◽  
Muscle Work ◽  
Mixed Venous

We have recently demonstrated that changes in the work of breathing during maximal exercise affect leg blood flow and leg vascular conductance (C. A. Harms, M. A. Babcock, S. R. McClaran, D. F. Pegelow, G. A. Nickele, W. B. Nelson, and J. A. Dempsey. J. Appl. Physiol. 82: 1573–1583, 1997). Our present study examined the effects of changes in the work of breathing on cardiac output (CO) during maximal exercise. Eight male cyclists [maximal O2 consumption (V˙o 2 max): 62 ± 5 ml ⋅ kg−1 ⋅ min−1] performed repeated 2.5-min bouts of cycle exercise atV˙o 2 max. Inspiratory muscle work was either 1) at control levels [inspiratory esophageal pressure (Pes): −27.8 ± 0.6 cmH2O], 2) reduced via a proportional-assist ventilator (Pes: −16.3 ± 0.5 cmH2O), or 3) increased via resistive loads (Pes: −35.6 ± 0.8 cmH2O). O2 contents measured in arterial and mixed venous blood were used to calculate CO via the direct Fick method. Stroke volume, CO, and pulmonary O2 consumption (V˙o 2) were not different ( P > 0.05) between control and loaded trials atV˙o 2 max but were lower (−8, −9, and −7%, respectively) than control with inspiratory muscle unloading atV˙o 2 max. The arterial-mixed venous O2difference was unchanged with unloading or loading. We combined these findings with our recent study to show that the respiratory muscle work normally expended during maximal exercise has two significant effects on the cardiovascular system: 1) up to 14–16% of the CO is directed to the respiratory muscles; and 2) local reflex vasoconstriction significantly compromises blood flow to leg locomotor muscles.

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.

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