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Applying deep learning to the classification of exercise electrocardiography symptoms
Published in Artde Donald Kin-Tak Lam, Stephen D. Prior, Sheng-Joue Young, Siu-Tsen Shen, Liang-Wen Ji, System Innovation in a Post-Pandemic World, 2022
Chun-Yen Chen, Shie-Jue Lee, Hsiang-Chun Lee, Ching-Yi Tsa, Su-Te Chen, Yu-Ju Li
Exercise can increase cardiac output by five times from the resting status, via multiple adaptations in the heart, including the increased venous return, increased heart rate, ventricular systolic force, stroke volume, and increased sympathetic nervous system activity. The acute increase over cardiac workload can be reflected by voltage changes of P- QRS-T waves in the ECG. For instance, changes of R wave amplitude in the ECG during exercise were first described by Simonson in 1953 (Simonson, E. et al. 1953). Later, changes in P-waves were described by Irisawa in 1966 (Irisawa, H. et al. 1966). The changes of P-waves during a submaximal exercise test include: (1) the peak P to Q interval shorting during exercise and lengthened in the recovery period; (2) the spatial magnitude increase during exercise; (3) a further augmentation of P-wave magnitude in the first minute of recovery.
New Technology and the Future
Published in Ervan Garrison, A History of Engineering and Technology Artful Methods, 2018
As blood is considered a tissue, circulating it through pumps and tubing can cause trauma to its cellular makeup. To prevent this, heparin is used to prevent clotting of any injured cells. Heat exchangers prevent the blood temperature from falling below body-ambient level. Hemolysis must be prevented and the venous flow must be saturated with oxygen while removing the carbon dioxide. The oxygenator (lung) must not traumatize the blood. All these were conditions in Gibbon’s design. The blood was moved by roller and finger type pumps. These pumps have no valves and have no direct contact with the blood. They have constant pressure at flows up to 6 liters per minute. The finger type pump uses the principle of serial compression of an elastic tube by parallel metal arms. In the roller type pump, two or more rollers, mounted at the ends of a horizontal revolving bar performs successive compression of tubing. As one roller leaves the tube, the second begins to compress it. Re-expansion of the tubes after compression provides the required suction of the pump. A typical anesthetized patient has a cardiac output of three to four liters per minute per square meter of body area. Flows 2.4 liters/minute do not produce metabolic difficulties. Body temperature plays a role here in that below 30°C, flow rates should be reduced as oxygen requirements are reduced by half.
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The left ventricle ejects approximately 70 mL during each beat (this is known as the stroke volume) and about 5 L per minute (known as the cardiac output). Cardiac output is the product of stroke volume and heart rate. Stroke volume is dependent on the contractile ability of the heart muscle, as well as the amount of blood in the ventricles at the end of filling (the end-diastolic volume, or EDV). Commonly, the EDV in the left ventricle will be in the range of 110–120 mL. After contraction, the end-systolic volume (or ESV) ranges from 40 to 50 mL. The difference between the EDV and the ESV is the stroke volume. Clinically, the term ejection fraction is often used, which represents the stroke volume as a percentage of the EDV. Normal ejection fractions are approximately 66%–68%.
Modified electrode placements for measurement of hemodynamic parameters using impedance cardiography
Published in Journal of Medical Engineering & Technology, 2020
Vu Duy Hai, Phan Dang Hung, Chu Quang Dan
Cardiac output (CO) is the volume of blood pumped into the aorta each minute by the heart and is perhaps the most significant factor to be considered in relation to the circulation. Some of the possible reasons for increase in the cardiac output to above normal are beriberi, anaemia, hyperthyroidism, arteriovenous fistula [1]. Besides, there are some factors decreasing the cardiac output under the normal value like decreased blood volume, acute venous dilation, obstruction of the large veins, or decreased tissue mass, especially decreased skeletal muscle mass. Therefore, determining cardiac output is an important parameter for detecting abnormalities related to circulation, interventional cardiology and is used during cardiothoracic surgery [1].
Relationship between heat loss indexes and physiological indicators of turnout-related heat strain in mild and hot environments
Published in International Journal of Occupational Safety and Ergonomics, 2023
Huipu Gao, A. Shawn Deaton, Roger Barker, Xiaomeng Fang, Kyle Watson
Figures 8a–10a show the predicted effects that study turnout systems have on cardiac output in different environmental conditions. The cardiac output prediction was provided by our manikin physiological model. The cardiac output was predicted according to metabolic rate, skin temperature, hypothalamus temperature, vasodilatation, vasoconstriction, etc. More details can be found in Fiala et al. [18,19]. Cardiac output is the product of heart rate and stroke volume. Stroke volume can increase in heat stressful conditions; increased heart rate is the primary driving force behind increased cardiac output [20]. An increase in cardiac output is a physiological response to human heat stress [21].