Quiz 4 Flashcards
- How is the velocity of blood flow related to the cross-sectional area of a blood vessel or group of blood vessels?
Velocity is inversely related to cross-sectional area
V=Q(flow)/A(cross-sectional area)
- Name a return-to-flow technique of blood pressure measurement.
- Palpation
- Pulse ox (plethysmographic waveform)
- arterial catheter
- In a healthy individual with disease-free arteries, does systolic blood pressure increase or decrease in the leg relative to the proximal aorta?
Increases
- What are the 3 waves seen in a normal CVP tracing?
- a - right atrial contraction (correlates with p wave)
- c - tricuspid valve/ventricular contraction (end of QRS)
- v - blood filling R atrium (end of T wave)
- What are the different waveforms that would be encountered when inserting a Swan-Ganz catheter from its insertion in the right jugular vein to its final position in a pulmonary artery?
- RV pressure
- PA Pressure
- Wedge pressure
- What information can be gathered from a Swan-Ganz catheter? DIRECTLY
- CVP
- RA/RV pressures
- PA pressures
- PAOP/Wedge
- CO
- SvO2
- What are the 2 steps of “zeroing” a transducer?
-Zero
-Appropriate height relative to patient position
(5 cm below the left sternal border at the fourth intercostal space)
- What is the Fick Principle method of measuring cardiac output?
o2 per minute absorbed by lungs/arteriovenous o2 difference
- What is cerebral perfusion pressure?
The difference between arterial and venous pressures
MAP – CVP or ICP (whichever is higher)
- What is Poiseuille’s Law? and what components (3)
Determines resistance to flow
(Radius, Length, Viscosity
- According to Poiseuille’s Law what factor has the greatest impact on the rate of blood flow through a vessel?
Radius
- What is resistance?
Resistance is the impediment to blood flow in a vessel
- Can resistance be measured directly?
no
- What is the formula for calculating Systemic Vascular Resistance?
(MAP - CVP)/CO x 80
- What is the formula for calculating Pulmonary Vascular Resistance?
(MPAP - PCWP)/CO x 80
- How would you calculate resistance when blood vessels are arranged in series?
add up the resistances to get total
R1 + R2 = Rtotal
- How would you calculate resistance when blood vessels are arranged in parallel?
1/R1 + 1/R2 = 1/Rtotal
note: the total resistance is less than any single blood vessel also means better flow total than single vessel
- If you added another blood vessel in a parallel arrangement, would total vascular resistance increase or decrease? Why?
Decrease
- What is laminar flow?
Smooth flow
- What is turbulent flow?
the blood flows crosswise in the vessel and along the vessel, usually forming whorls in the blood, callededdy currents
- What formula could you use to predict laminar versus turbulent flow?
Reynold number
Density, Diameter, Viscosity, Velocity
- What is the relationship of hematocrit to blood viscosity?
More hematocrit, more viscosity
- As blood pressure increases within a vessel why does blood flow increase much greater than one would expect? what law? Ohms
because (P.arterial - P.venous)/Radius = flow
Ohms law
- What is the most important monitor in the operating room?
The anesthetist
- What is damping in an arterial line tracing?
How quickly vibrations come to rest
- What is ringing in an arterial line tracing? What range?
When the fast flush abruptly ends, the transducer system oscillates at its natural frequency. This can be measured and assessed for adequacy.
> 24 hz
- According to Ohm’s Law what 2 factors determine blood flow through a blood vessel?
Pressure or voltage drop, resistance
- Define blood pressure.
Blood pressure is the force exerted by the blood against any unit area of the vessel wall
- What is the conversion factor from mm-Hg (mercury) to cm-H2O?
1 mmHg = 1.36 cm H2O
excessive damping leads to
underestimated systolic and overestimated diastolic
Underdamping leads to
overestimated systolic and underestimated diastolic
