Chest
Clinical InvestigationsTechniquesComparison of Exercise Cardiac Output by the Fick Principle Using Oxygen and Carbon Dioxide*
Section snippets
Subjects and Preliminary Ramp Exercise Testing
The Human Subjects Committee at Harbor-UCLA Medical Center approved the researchprotocol. After informed consent, five healthy nonsmoking male subjectsperformed a preliminary noninvasive increasing work rate exercise teston an electromagnetically braked cycle ergometer (type 18070;Gould-Godart; Bilthoven, Netherlands) to determine their maximum workrate, anaerobic threshold (AT), and maximal, o2( o2max). During each test, apedal frequency of 60 revolutions/min was maintained
Blood Analysis
The blood samples were agitated and immediately chilled in ice slurry. Blood gas analysis was performedwith an Instrumentation Laboratory (IL) 1306 blood gas analyzer(Instrumentation Laboratory; Lexington, MA) for p, H,Pco2, and , Po2, and with an IL 482 co-oximeter(Instrumentation Laboratory) for total Hb and , So2. The measured values obtainedwere corrected for heparin dilution. The analyzer precision wasverified with quality control materials every 20 to 30 min.
Respired Gas Analysis
The subjects respired througha
Calculations of Blood O2 and CO2Contents
Blood O2 contents(Cbo2) in milliliters per deciliter werecalculated from the following equation:231213141516 where Hb is hemoglobin concentration in grams per deciliter,So2 is O2 saturation in percent, and Po2 is O2 partial pressure inmillimeters of mercury.
Plasma CO2 contents(Cplco2) were calculated from thestandard formula derived from the Henderson–Hasselbachequation17181920: where 2.226 is the conversion factor
Exercise Studies and Blood Values
The subject’s physical characteristics and the work rate at ATand maximal exercise of test A and test B are shown in Table 1. There was no significant difference between the two tests. o2 increased at a rate of10.30 ± 0.70 m, L/min/W during exercise.
Because the duration of exercise varied slightly between subjects, blood values were grouped according to exercise intensity (Table 2). Both arterial and venous Hb significantly increased from restingvalues during exercise from AT to maximal
Comparison of CO[o2] WithCO[co2]
Confirming the Fick principle,1 the ratio of the meanvalues of CO[co2] was similar tothat of CO[o2], both at rest(0.99 ± 0.04) and during exercise (1.00 ± 0.13), when accuratemeasures and correct formulas and calculations were used (Fig 3 and Table 3). The overall difference of these two methods for COcalculation was negligible. Inasmuch as, co2 is a simpler measurementthan o2, it would be temptingto suggest that CO2 might be the more optimaltest gas for CO measurements.
References (49)
- et al.
Continual trending of Fick variables in the critically ill patient
Chest
(1991) - et al.
Patterns of dissimilarities among instrument models in measuring Po2, Pco2, and pH in blood gas laboratories
Chest
(1998) - et al.
The physiology of oxygen transport
Transfus Sci
(1997) - et al.
Relation of oxygen uptake in low work rate in normal men and men with circulatory disorders
Am J Cardiol
(1987) Uber die Blutquantums in den Herzventrikeln
Sitzung Phys med Gesell Wu¨rzburg
(1870)- et al.
Cardiac output estimated noninvasively from oxygen uptake during exercise
J Appl Physiol
(1997) - et al.
Continuous Fick cardiac output compared to continuous pulmonary artery electromagnetic flow measurement in pigs
Anesthesiology
(1987) - et al.
Frequently repeated Fick cardiac output measurements during anesthesia
J Clin Monit
(1990) - et al.
Continuous measurement of cardiac output by the Fick principle: clinical validation in the intensive care
Crit Care Med
(1992) Measurement of cardiac output using soluble gases
Effect of measurement errors on cardiac output calculated with and modified Fick methods
J Clin Monit
Measurement and analysis of gas exchange during exercise using a programmable calculator
J Appl Physiol
A new method for detecting the anaerobic threshold by gas exchange
J Appl Physiol
Neue versuche zur bestimung der saueratoffkapazita¨t des blutfarbstoffes
Arch Anat Physiol
Continuous Fick cardiac output compared to thermodilution cardiac output
Crit Care Med
Increasing maximal heart rate increases maximal O2uptake in rats acclimatized to simulated altitude
J Appl Physiol
Value of the venous-arterial Pco2gradient to reflect the oxygen supply to demand in humans: effects of dobutamine
Crit Care Med
Calculation of whole blood CO2content
J Appl Physiol
Respiratory and circulatory analysis of CO2output during exercise in chronic heart failure
Circulation
The relationship between the differences in pressure and content of carbon dioxide in arterial and venous blood
Clin Sci
Nunn's applied respiratory physiology
Solubility of CO2in serum from 15 to 38°C
J Appl Physiol
Digital computer procedure for the conversion of Pco2into blood content
Respir Physiol
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Supported in part by the Milly Liang Liu, MD, and Steve C. K. Liu, MD,Research Fund.
{altfoot}*From the Division of Respiratory and Critical Care Physiology and Medicine, Department of Medicine, Harbor-UCLAMedical Center, St. John’s Cardiovascular Research Center, Torrance,CA.