Clinical measurement of blood flow

Question 1

Blood flow functions

Answer 1

• Delivery of O2 and nutrients
• Removal of metabolism waste products - acid
• Distributing heat
• Endocrine and paracrine signalling
• Delivering immune responses to infection
• To survive you must avoid hypoxia and acidosis

Question 2

Pick principle

Answer 2

• Blood flow can be calculated if you know: the amount of marker taken up per unit time, the concentration of marker in arterial blood and the concentration of marker in venous blood
• Putting a marker substance into a vessel and measuring the amount in the venous and arterial ends allows you to calculate blood flow
• Markers include oxygen, co2, lithium and temperature
• Can also use Swam-Ganz catheter (pulmonary artery catheter)

Question 3

Fast Fourier analysis

Answer 3

Converts signals into individual waveforms

Question 4

Ways to manipulate blood flow

Answer 4

• HR - chronotopes
• Filling state - fluid bolus, diuretics
• Ionotropy/contractility
• Vascular resistance (constriction or dilation)