Cardiovascular Physiology — Cardiac Output
Normal values for cardiac output
CO = HR × SVO — l/min
CI = HR / bsa — l/min/m2
Control of cardiac output
Frank-Starling mechanism
venous return
stretch of SA node
Bainbridge reflex
CO results from local flow
TPR effects on CO
CO = Part / TPR
limits on CO
hypereffective heart
nervous stimulation
sympathetic stimulation
parasympathetic inhibition
positive chronotropy & inotropy
myocardial hypertrophy
hypoeffective heart
nervous system & CO
arterial pressure increase during exercise
High CO pathology
beriberi
thiamine (vitamin B1 deficiency
arteriovenous fistula (AV shunt)
hyperthyroidism
anemia
reduction in blood viscosity
vasodilation from hypoxia
Low CO pathology
cardiogenic
cardiac shock
noncardiogenic
↓ blood volume
acute venous dilation
large vein obstruction
↓ tissue mass
circulatory shock
Measuring cardiac output
oxygen-Fick method
CO = absorbed O2 / AV O2 difference
thermodilution method
Swan-Ganz catheter
indicator-dilution method
CO = ((amount of indicator injected) * 60) / ((mean concentration of indicator in the blood) * (time of total curve duration))
ultrafast computed tomography