cv wk 4 hemodynamic measurements

Question 1

what is the most important monitor in the operating room?

Answer 1

the anesthetist

Question 2

Name a return-to-flow technique of blood pressure measurement

Answer 2

palpation,
pulse oximeter (plethysmographic),
indwelling arterial catheter

Question 3

name several insertion sites for arterial catheters

Answer 3

radial, 
brachial,
femoral,
dorsalis pedis,
axillary, 
ulnar artery

Question 4

In a healthy individual with disease-free arteries, does systolic blood pressure increase or decrease in the leg relative to the proximal aorta?

Answer 4

systolic BP increases while diastolic BP decreases, creating an increase in pulse pressure. This occurs because of reflective waves from vessel branching, and from decreased arterialcompliance(increased vessel stiffness) as the pressure pulse travels from the aorta into systemic arterie. MAP only slightly decreases

Question 5

3 waves of CVP

Answer 5

a) wave- atrial contraction
c) RV begins to contract CUSP of tricuspid valve protrudes backwards through RA
v) as blood fills the right atrium, it hits the tricuspid valve and this the back-pressure wave.

Question 6

8. 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?

Answer 6

1. CVP
2. Right ventricle
3. pulmonary artery
4. wedge

Question 7

what are direct measurements that can be gathered by a swan ganz

Answer 7

CVP, 
Right-sided intracardiac pressures, 
pulmonary arterial pressures, 
wedge pressure, 
mixed venous oxyhemoglobin saturation

Question 8

what are measurements that a swan ganz or pac indirectly measure

Answer 8

SVR, 
PVR, 
CI, 
Stroke volume index, 
Right ventricular stroke work index, 
LV stroke work index,
oxygen delivery, 
oxygen uptake

Question 9

First step to zero transducer

Answer 9

Establishing a standard reference value, ambient atmospheric pressure, which is assigned the value of 0 mm Hg and used as the reference point for all subsequent intravascular pressure measurements

Question 10

second step to zero transducer

Answer 10

The second step in transducer setup involves placing the transducer at the appropriate vertical height relative to the patient’s position.

Question 11

Fick measurement equation for CO

Answer 11

O2 per minute absorbed by the lungs (ml/min) / Arteriovenous O2 difference (mL/ L of blood)

Question 12

what is the thermodilution method for measuring CO?

Answer 12

Based on the indicator dilution technique and utilizes temperature as the indicator
A known amount of indicator (saline) at a known temperature (lower than blood) is injected into the right atrium
This indicator mixes with blood lowering its temperature
The temperature is measured near the tip of the catheter; the change over time expressed as the area under the curve is planimetered to calculate the cardiac output

Question 13

how is the velocity of blood flow related to the cross-sectional area of a blood vessel or group of blood vessels?

Answer 13

Velocity is inversely related to cross-sectional area.

Question 14

according to ohm’s law what 2 factors determine blood flow through a blood vessel?

Answer 14

I (current flow) = V (voltage drop, apressure-vpressure) / R (resistance)

Question 15

Define blood pressure

Answer 15

Blood pressure is the force exerted by the blood against any unit area of the vessel wall

Question 16

conversion factor from mmHg to cmH2O

Answer 16

1.36

Question 17

What is cerebral perfusion pressure?

Answer 17

MAP-CVP or ICP (whichever is higher)

Question 18

Poiseuille’s law

Answer 18

Q = Pie(Pi-Po)r^4 / 8nL

n=viscosity

Question 19

Poiseuille’s what factor has the greatest impact on the rate of blood flow through a vessel?

Answer 19

Flow varies directly as the fourth power of the radius

Question 20

What is resistance?

Answer 20

Resistance is the impediment to blood flow in a vessel and cannot be measured directly

Question 21

SVR=

Answer 21

(MAP-CVP)80/CO

Question 22

PVR=

Answer 22

(MPAP-MCWP)80/CO

Question 23

How would you calculate resistance when blood vessels are arranged in series?

Answer 23

R1+R2+R3…

Question 24

Resistance=

Answer 24

Pi-Po / Q

Question 25

Flow =

Answer 25

(Pa-Pv) / R

Question 26

How would you calculate resistance when blood vessels are arranged in parallel?

Answer 26

1/ (1/R1 + 1/R2 + 1/R3)…

Question 27

14. If you added another blood vessel in a parallel arrangement, would total vascular resistance increase or decrease? Why?

Answer 27

Decrease, dividing 1 by Rtotal, as total increases, fraction becomes smaller 1/4 vs 1/5

Question 28

what is laminar flow?

Answer 28

fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing.

Question 29

what is turbulent flow?

Answer 29

flow in which the fluid undergoes irregular fluctuations, or mixing

Question 30

what formula can you sue to predict laminar vs turbulent flow?

Answer 30

Reynolds number. NR=(density x tube diameter x mvelocity) / viscosity

Question 31

what is the relationship of hematocrit to blood viscosity?

Answer 31

Directly proportional, As hct increases, viscosity increases

Question 32

19. As blood pressure increases within a vessel why does blood flow increase much greater than one would expect?

Answer 32

Flow=Pressure/Resistance, sympathetic stimulation?

Question 33

5. What is damping in an arterial line tracing?

Answer 33

how quickly the vibrations come to a rest

Question 34

what is ringing in an arterial line tracing?

Answer 34

Ringing” or oscillations below and above the baseline. This leads to false-high systolic
pressures and false-low diastolic pressures. Peak systolic tracings may show more than
one sharp upstroke and diastolic points are hard to differentiate. The MAP is usually
accurate.