Ch 8-11

Question 1

In shock, which BP should you trust? CVP? A-line? Cuff? Why?

Answer 1

CVP because cuff can underestimate by an average 30mmhg

Question 2

When is an arterial pressure unreliable?

Answer 2

when vascular impedance is abnormal

Question 3

What happens to systolic pressure as it is measured further and further in the periphery?

Answer 3

it gradually increases

Question 4

What is the most accurate measure of central aortic pressure?

Answer 4

MAP

Question 5

What other factor significantly amplifies systolic pressure?

Answer 5

noncompliant arteries

Question 6

What is the most common cause of inaccurate MAPs?

Answer 6

heart rates over 60bpm

Question 7

How many channels does a typical PA catheter have?

Answer 7

2

Question 8

What is the placement of the tips of the two lumens?

Answer 8

PA and right atrium (30cm)

Question 9

How does the PA catheter measure CO?

Answer 9

thermistor (temperature change detector) measures the flow of cold fluid injected by the proximal catheter as it passes the distal sensor

Question 10

identify wave forms (pic)

Answer 10

right atrium, rv, wedge PA, PA

Question 11

what is the normal systolic right ventricle pressure?

Answer 11

15-30mmHg

Question 12

What is normal PA diastolic pressure?

Answer 12

6-12mmHg

Question 13

Define the pulmonary capillary wedge pressure (aka wedge pressure)?

Answer 13

venous pressure in the left side of the heart representing the left atrial pressure and LV diastolic pressure

Question 14

What do you have to do to the catheter on initial insertion to get an appropriate wedge pressure reading?

Answer 14

inflate the balloon so that the wedge pressure is obtained (asystole looking wave form) then deflate the balloon so that the wave form reappears

Question 15

What should you do if a patient has a complete heart block with the catheter in place?

Answer 15

withdraw the catheter

Question 16

What if the wedge pressure is not producing a reading?

Answer 16

use the pulmonary artery diastolic pressure as a substitute

Question 17

When measuring CO how many measurements are necessary?

Answer 17

at least 3 if they differ by less than 10%

Question 18

What if the CO measurement drops by 10% and the patient is asymptomatic?

Answer 18

That is a normal variation in the measurement process

Question 19

What is the formula for calculating pulmonary vascular resistance?

Answer 19

PVR = PAP (mean pulmonary artery pressure) - wedge pressure

Question 20

What kind of hypotension is associated with low CVP, low cardiac index and high systemic vascular resistance?

Answer 20

hypovolemic hypotension

Question 21

What kind of hypotension is associated with high CVP, low cardiac index and high systemic vascular resistance?

Answer 21

cardiogenic hypotension

Question 22

What kind of hypotension is associated with low CVP, high cardiac index and low systemic vascular resistance?

Answer 22

vasogenic hypotension

Question 23

What kind of shock is associated with high CVP, low cardiac index, high systemic vascular resistance, normal venous O2?

Answer 23

heart failure shock (low output state)

Question 24

What kind of shock is associated with high CVP, low cardiac index, high systemic vascular resistance, low venous O2?

Answer 24

cardiogenic shock

Question 25

What is the positional consideration when measuring wedge pressure?

Answer 25

the patient should not be in the lateral position because it will be inaccurate

Question 26

When shoul dintravascular pressures be measured?

Answer 26

at the end of expiration

Question 27

When will transmural pressures differ at end-expiration?

Answer 27

only if there is positive intrathoracic pressure as in mechanical ventillation which prevents complete alveolar emptying

Question 28

In a ventilator dependent patient, when should intravascular pressures be measured?

Answer 28

at end-expiration when disconnected from a ventilator momentarily

Question 29

In a spontaneously breathing patient vs ventilated patient what is the end-expiratory pressure difference?

Answer 29

In spontaneous it is the highest pressure and in ventilated it is the lowest pressure

Question 30

What is the benchmark for a significant change in CVP or wedge pressure?

Answer 30

4mmHg

Question 31

picture a normal CVP tracing, explain components

Answer 31

(pic)

Question 32

what anatomical consideration should be taken in to account when taking a wedge pressure

Answer 32

Wedge pressures are only accurate from lung regions below the left atrium

Question 33

How do you check to ensure that the pulmonary catheter tip is in the correct position in a supine patient?

Answer 33

check lateral chest xray, no marked respiratory variations in wedge pressure and wedge pressure increases

Question 34

Under which conditions is there a discrepancy between left-atrial pressure and left-ventricular end-diastolic pressure (3)?

Answer 34

aortic insufficiency, noncompliant ventricle, respiratory failure

Question 35

You have a patient with low calculated VO2, what should you check next?

Answer 35

ensure that the patient does not have lung inflammation because that will cause the calculated value to be underestimated by as much as 20%

Question 36

What is considered a significant change in calculated VO2?

Answer 36

greater than 18-20%

Question 37

What is considered a significant change in measured VO2?

Answer 37

greater than 5%

Question 38

How is VO2 correlated with tissue oxygenation?

Answer 38

Values below 100 mL/min/m2 are indicative of impaired tissue oxygenation

Question 39

What are the three ways to correct VO2 deficits?

Answer 39

Augment cardiac output, correct anemia and correct hypoxemia

Question 40

If a patient with low cardiac output (s the next step in evaluation?

Answer 40

measure the ventricular filling pressure (CVP or PCWP)

Question 41

How do you treat low CO with low CVP?

Answer 41

volume resuscitation until a CVP of 10 or PCWP of 15

Question 42

How do you treat low CO with normal/high CVP?

Answer 42

dobutamine (inotrope)

Question 43

In what situation should anemia be corrected?

Answer 43

hgb \< 7

Question 44

What side effect of transfusion can decrease VO2?

Answer 44

increases blood viscosity and decreases cardiac output as a result

Question 45

To what extent should hypoxia be corrected?

Answer 45

to 90% unless the patient is in septic shock in which case oxygen utilization is the issue rather than availability

Question 46

What is the mechanism of increased oxygen utilization in sepsis?

Answer 46

increases in released neutrophils and macrophages have significantly increased oxygen consumption. Called respiratory burst.

Question 47

How is decreased oxygen delivery measured?

Answer 47

venous O2 sat below 70%

Question 48

At what critical value is venous O2 too low?

Answer 48

venous O2 below 50% indicates a global state of tissue dysoxia or impending dysoxia

Question 49

What is considered a significant changed in measured venous O2 Sat?

Answer 49

greater than 5%

Question 50

What is considered an abnormal lactate level?

Answer 50

above 2 but above 4 impacts morbidity/mortality

Question 51

What are other sources of hyperlactatemia besides hypoperfusion(4)?

Answer 51

hepatic insufficiency (reduced clearance), thiamine deficiency (inhibits storage), severe sepsis (endotoxin accumulation), intracellular alkalosis (glycolysis stimulation increases lactate production)