Fully automatic, noninvasive measurement of cardiac output by means of the CO2 rebreathing method and its clinical application to hypertensive patients.

Cardiac output (Q) was estimated in supine rest and in upright cycling at several work rates up to 200 W in five male and one female subjects. At least four repetitions of both the CO2-rebreathing plateau method (Collier, J. Appl. Physiol. 9:25–29, 1956) and the Kim et al. (J. Appl. Physiol. 21: 1338–1344, 1966) single-breath method were performed at each work rate, in a steady state of O2 consumption and heart rate. At supine rest and low work rates, estimates of Q were similar by the two methods. However, at higher work rates, the single-breath method significantly (P less than 0.05) underestimated the value obtained by CO2 rebreathing. The reason for the difference in estimates of Q by the two methods was traced to the determination of arterial partial pressure of CO2 (PaCO2) and mixed venous partial pressure of CO2 (PvCO2). The estimate of PaCO2 from the single-breath method was approximately 88.5% of the estimate from end-tidal PCO2 used with the rebreathing method (P less than 0.001). The oxygenated PvCO2 calculated from the single-breath Q averaged approximately 92.5% of the PvCO2 from CO2 rebreathing (P less than 0.0001). The difference in estimates of Q was not eliminated by using a logarithmic form of the CO2 dissociation curve with the single-breath method.

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Comparative Noninvasive Measurement of Cardiac Output Based on the Inert Gas Rebreathing Method (Innocor®) and MRI in Patients with Univentricular Hearts

10.1055/s-0038-1628345 ◽

2018 ◽

Author(s):

M. Kuhn ◽

A. Hornung ◽

L. Sieverding ◽

C. Schlensak ◽

M. Hofbeck ◽

...

Keyword(s):

Cardiac Output ◽

Noninvasive Measurement ◽

Inert Gas ◽

Inert Gas Rebreathing ◽

Rebreathing Method

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Comparison of CO2 rebreathing and acetylene methods for cardiac output

Journal of Applied Physiology ◽

10.1152/jappl.1965.20.4.763 ◽

1965 ◽

Vol 20 (4) ◽

pp. 763-766 ◽

Cited By ~ 47

Author(s):

K. Klausen

Keyword(s):

Cardiac Output ◽

Partial Pressure ◽

Venous Blood ◽

Mixed Venous Blood ◽

Co2 Rebreathing ◽

Arterial Blood ◽

Co2 Output ◽

Partial Pressure Of Co2 ◽

Douglas Bag ◽

Rebreathing Method

The cardiac output during rest and work was determined by a CO2 rebreathing method as suggested by Defares. The partial pressure of CO2 in the mixed venous blood (PvCOCO2) was calculated from the rise of the CO2 percent in a Grollman bag during rebreathing. In the rest experiments the partial pressure of CO2 in arterial blood (PaCOCO2) was obtained from analysis of alveolar samples taken by the Haldane-Priestley direct sampling method. In the work experiments the PaCOCO2 was calculated using the Bohr formula and a dead space estimated from Asmussen and Nielsen's data. The metabolic rate including both O2 uptake and CO2 output was determined by the Douglas bag method. In each experiment the acetylene method as described by Christensen was applied after the CO2 rebreathing method. The values obtained by the two methods were almost identical, the standard deviation for all experiments being ±7.3%, and were of the same magnitude as those obtained by others with the dye-dilution or direct Fick method both during rest and work. cardiac output at rest and work; arterial Pco2 and venous Pco2 at rest and work; stroke volume at rest and work Submitted on November 25, 1964

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Cardiac output in middle-aged patients determined with CO2 rebreathing method

Journal of Applied Physiology ◽

10.1152/jappl.1970.28.3.337 ◽

1970 ◽

Vol 28 (3) ◽

pp. 337-342 ◽

Cited By ~ 35

Author(s):

J. P. Clausen ◽

O. A. Larsen ◽

J. Trap-Jensen

Keyword(s):

Cardiac Output ◽

Middle Aged ◽

Aged Patients ◽

Co2 Rebreathing ◽

Rebreathing Method

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Estimation of cardiac output by the CO2 rebreathing method during tethered swimming

Journal of Applied Physiology ◽

10.1152/jappl.1978.44.5.821 ◽

1978 ◽

Vol 44 (5) ◽

pp. 821-824 ◽

Cited By ~ 3

Author(s):

G. J. Heigenhauser ◽

J. A. Faulkner

Keyword(s):

Cardiac Output ◽

Oxygen Uptake ◽

Treadmill Walking ◽

Dilution Method ◽

Published Data ◽

Free Swimming ◽

Dye Dilution ◽

Co2 Rebreathing ◽

Rebreathing Method

The reproducibility of cardiac output (Q) estimated by the CO2 rebreathing method during tethered swimming was studied in five highly trained college swimmers. The reproducibility of the CO2 rebreathing method for estimations of Q during tethered swimming was similar to the reproducibility reported for the CO2 rebreathing method, direct Fick method, or dye-dilution method during either cycling or treadmill walking. All duplicate estimates of Q by the CO2 rebreathing method were within 15% of one another. A comparison was made between the Q's estimated by the CO2 rebreathing method during tethered swimming and previously published data on Q determined by the dye-dilution method during free swimming in a flune. At any given oxygen uptake, Q obtained by the CO2 rebreathing method during tethered swimming was not significantly different from the Q obtained by the dye-dilution method during flume swimming. Estimates of Q by the CO2 rebreathing method made during high intensities of tethered swimming were reproducible and appear to be valid.

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