Key result
Mixed venous oxygen saturation and physical activity correlated strongly with cardiac output changes during exercise, supporting their use as parameters for TAH control.
Why the study?
Do mixed venous oxygen saturation and physical activity correlate with cardiac output changes during exercise for total artificial heart control?
Do mixed venous oxygen saturation and physical activity correlate with cardiac output changes during exercise for total artificial heart control?
Mixed venous oxygen saturation and physical activity are useful parameters with complementary characteristics (correlation vs. response time) for total artificial heart control during exercise.
Answers are grounded in this paper and cite their sources.
May inform TAH control algorithms during exercise; hypothesis-generating and requires prospective validation.
Mixed venous oxygen saturation (SvO2) and physical activity (PhyAc) are practical candidates as parameters of total artificial heart (TAH) control because SvO2 can be measured through a transparent blood pump housing with infrared rays and PhyAc can be calculated from signals of an accelerometer used for rate response pacemakers. Although the methods for measurement of the parameters have already been developed, characteristics of these parameters for TAH control, such as during exercise, are still unclear and were examined in this study. SvO2, cardiac output (CO), and PhyAc were measured as parameters. Multi-stage treadmill exercise tests were performed. Difference values (DVs) from the value at the start of exercise showed better correlation than did absolute values. Correlation coefficients between DV in CO and DV in SvO2 and between DV in CO and PhyAc were high at -0.82 and 0.72, while the time constants for the change of SvO2 and CO to the PhyAc change were 26 and 32 sec. Although the correlation coefficient between the CO and SvO2 was higher than that between CO and PhyAc, PhyAc responded more quickly to the speed change compared with the response of SvO2 and CO. It was concluded that SvO2 and PhyAc were useful parameters with different characteristics for TAH control during exercise.
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Ohno et al. (1997) studied Total artificial heart (TAH) control. Mixed venous oxygen saturation (SvO2) and physical activity (PhyAc) monitoring was evaluated on Correlation between difference values in cardiac output (CO) and SvO2/PhyAc during multi-stage treadmill exercise tests (r = -0.82 for CO and SvO2; r = 0.72 for CO and PhyAc). Mixed venous oxygen saturation and physical activity correlated strongly with cardiac output changes during exercise, supporting their use as parameters for TAH control.
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