Haemodynamics Flashcards
What is in unclotted vs clotted whole blood
Unclotted = RBC + buffy coat + plasma. Clotted = clot + serum
Define serum
Plasma minus the clotting factors (in particular fibrinogen)
What type of system is the CVS?
Closed system
What is the cause of raised whole blood viscosity?
Increase in RBC (polycythaemia), platelets (thrombocythaemia) or WBC (leukaemia) = increased whole blood viscosity/sludging of blood in peripheries e.g. Multiple myeloma. Also high protein and cool temp raises blood viscosity
What is c-reactive protein CRP?
Measure of inflammation in the blood: acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages and T cells
What is the difference between flow and velocity?
Flow = amount in a given direction. Velocity = speed in a given direction
What is the difference between laminar and turbulent flow?
Laminar = streamlined flow in one direction with highest velocity in the middle of the lumen due to lower friction (parabolic profile).
Turbulent = flow in multiple directions with increased resistance
What causes a pulse?
Shockwave that arrives before blood, devel by left ventricle ejecting blood
Outline how to measure BP
Phase 1 = when sound starts = systolic
Phase 5 = when sound stops = diastolic
What are the units of blood flow?
Volume per unit of time: L/min
What does a descending aorta pressure tracing show?
Anacrotic limb: systole uptake, raising aortic pres, peak systolic pres
Diacrotic limb: systolic decline, diacrotic notch = valve shutting, diastole, lowering aortic pres, end-distolic pres
Pulse pres (diff between peak systolic pres and end-diastolic pres) Area under curve = mean arterial pres
What factor allows for high pressure in the aorta?
High levels of elastin = stretch and recoil
What is pulse pressure?
(systolic pressure – diastolic pressure) = (120mm Hg – 80 mm Hg) = 40mm Hg
Represents force the heart generates each contraction
What is mean arterial pressure?
(diastolic pressure + 1/3 of the pulse pressure) = (80 mmHg + 13 mmHg) = 93 mm Hg. If mean arterial pressure falls below 70 mm Hg then organ perfusion is impaired
Strength of a pulse is determined by what 2 factors?
Force which the left ventricle is able to eject blood (reduced vol = thready pulse), the pulse pressure (increased pressure = bounding pulse)
