To determine whether continuous Fick cardiac output measurement is applicable to exercise testing.

To determine whether continuous Fick cardiac output measurement is applicable to exercise testing, cardiac output data obtained by way of the continuous Fick method (Qcf) during exercise were compared with data obtained at the thermodilution method (Qth). Seventeen patients with of advanced age myocardinal infarction underwent a 1-min or 3-min incremental exercise criterion (protocols 1 and 2, respectively). During exercise, the oxygen consumption ([Vosub2]) arterial oxygen saturation ([SaO.sub.2]), and mixed venous oxygen saturation ([SvOsub2]) were monitored continuously. Qcf was calculated at 12- intervals by dint of the Fick equation. The [SaO.sub.2] remained almost constant during exercise. The [SvOsub2] showed four characteristic phases during exercise protocol 1 [SvOsub2] values changed rapidly in phases 2 and 4 yet only slightly during phase 3 In exercise protocol 2 [SvOsub2] almost reached a steady-state by the agency of the end of each stage. The correlation between Qcf and Qth was beneficial in protocol 1 (r = 086) save in phases 2 and 4 and was also serviceable in protocol 2 (r=V 080) We gather that the continuous Fick order may be applicable for determining the cardiac output during exercise provided that the variation in [SvOsub2] is slight.

For the measurement of cardiac output techniques like the coloring liquor dilution or thermodilution method are now used in clinical practice, as well as the Fick mode However, none of those techniques is ideal for the oft-repeated accurate, and constant measurement of cardiac output during exercise. This is because the tinge dilution method cannot be repeated frequently[1] the thermodilution regularity has problems with reproducibility and accuracy when measuring a high cardiac output during exercise,[2,3(p133)] and various hemodynamic parameters ne to be in a steady state to apply the Fick method[45]

Several studies have been performed involving continuous measurement of the arteriovenous oxygen make easy difference and oxygen consumption ([VOsub2]) and continuous calculation of the cardiac output employing the Fick principle.[6,7] However, appropriate to technical limitations, this means has not yet been bring forward into clinical practice. The fresh development of a combined classification with a flowmeter, a respiratory gas analyzer, and a microcomputer has enabled the breath-by-breath measurement of [VOsub2] to be performed.[8] Furthermore, the unfolding of an advanced fiberoptic reflectance oximetry theory and pulse oximetry have enabled the continuous and accurate measurement of mixed venous oxygen saturation ([SvOsub2])[9-13] and arterial line oxygen saturation ([SaO.sub.2]),[14,15] respectively. Consequently it has now become possible to continuously measure [SaO.sub.2], [SvOsub2] and [VOsub2] simultaneously and to calculate the cardiac output by dint of applying the Fick principle (continuous Fick cardiac output method) Although the continuous Fick cardiac output mode has already been used in several studies, its application was restricted to monitoring critically ill patients in the ICU or during cardiac surgery The instant study was carried out to investigate whether the continuous Fick cardiac output orderly disposition is also applicable to exercise testing.

METHODS

Patient Selection

We studied 17 patients with a mean ([+ or -] SD) age of 52 [+ or -] 12 years who had left ventricular dysfunction. All patients had a documented history of myocardial infarction that was treated in our coronary care unit about 1 month before the studious mood None of them had peripheral edema, ascites, intermittent claudication, or reduc beating [i]or[/i] throbbing of an arterys in the legs, or lung disease at the time of the investigation Two subjects were in novel York Heart Association functional class III, ten were in class II, and five were in class I. The mean left ventricular ejection fraction was 45 [+ or -] 15 percent at angiography or radionuclide ventriculography. A clinical profile of the enslaves is shown in Table 1 forward the day before the cogitation all subjects performed at least single in kind trial symptom-limited maximal exercise experiment before data collection to confirm that no ischemic conclusions occurred during exercise and to assume familiarization with the exercise protocol. The exercise experiment was performed at least 3 h after forage intake. All subjects gave informed compliance to the study. [TABULAR DATA OMITTED]

investigation Protocol

Patients were given their usual cardiac medications 3 h before testing. Then a 1-min incremental exercise example or 3-min incremental exercise ordeal was carried out with the subdues in the supine position using an electromechanically braked bicycle ergometer (model 380B Siemens-Elema). Expired gas analysis and hemodynamic monitoring were performed during the ordeal Heart rate was monitored from standard electrocardiography and BP was measured with a sphygmomanometer. In the 1-min incremental exercise ordeal the patients commenced exercise at a workload of 0 W for 2 min, and the load was increased by dint of 15 W every 60 s to the symptomatic maximum (protocol 1) This protocol was used for ten subdues In the 3-min incremental exercise ordeal three workload levels were excellented (0, 30, and 60 W) After an initial warm-up exercise workload of 0 W for 3 min, the workload was abruptly increased to 30 W for 3 min and then to 60 W for 3 min without interruption of pedaling (protocol 2) This protocol was performed in seven subjects

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