Ch 8-11 Flashcards Preview

The ICU Book by Paul Marino > Ch 8-11 > Flashcards

Flashcards in Ch 8-11 Deck (51)
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1
Q

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

A

CVP because cuff can underestimate by an average 30mmhg

2
Q

When is an arterial pressure unreliable?

A

when vascular impedance is abnormal

3
Q

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

A

it gradually increases

4
Q

What is the most accurate measure of central aortic pressure?

A

MAP

5
Q

What other factor significantly amplifies systolic pressure?

A

noncompliant arteries

6
Q

What is the most common cause of inaccurate MAPs?

A

heart rates over 60bpm

7
Q

How many channels does a typical PA catheter have?

A

2

8
Q

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

A

PA and right atrium (30cm)

9
Q

How does the PA catheter measure CO?

A

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

10
Q

identify wave forms (pic)

A

right atrium, rv, wedge PA, PA

11
Q

what is the normal systolic right ventricle pressure?

A

15-30mmHg

12
Q

What is normal PA diastolic pressure?

A

6-12mmHg

13
Q

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

A

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

14
Q

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

A

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

15
Q

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

A

withdraw the catheter

16
Q

What if the wedge pressure is not producing a reading?

A

use the pulmonary artery diastolic pressure as a substitute

17
Q

When measuring CO how many measurements are necessary?

A

at least 3 if they differ by less than 10%

18
Q

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

A

That is a normal variation in the measurement process

19
Q

What is the formula for calculating pulmonary vascular resistance?

A

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

20
Q

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

A

hypovolemic hypotension

21
Q

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

A

cardiogenic hypotension

22
Q

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

A

vasogenic hypotension

23
Q

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

A

heart failure shock (low output state)

24
Q

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

A

cardiogenic shock

25
Q

What is the positional consideration when measuring wedge pressure?

A

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

26
Q

When shoul dintravascular pressures be measured?

A

at the end of expiration

27
Q

When will transmural pressures differ at end-expiration?

A

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

28
Q

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

A

at end-expiration when disconnected from a ventilator momentarily

29
Q

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

A

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

30
Q

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

A

4mmHg

31
Q

picture a normal CVP tracing, explain components

A

(pic)

32
Q

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

A

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

33
Q

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

A

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

34
Q

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

A

aortic insufficiency, noncompliant ventricle, respiratory failure

35
Q

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

A

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

36
Q

What is considered a significant change in calculated VO2?

A

greater than 18-20%

37
Q

What is considered a significant change in measured VO2?

A

greater than 5%

38
Q

How is VO2 correlated with tissue oxygenation?

A

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

39
Q

What are the three ways to correct VO2 deficits?

A

Augment cardiac output, correct anemia and correct hypoxemia

40
Q

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

A

measure the ventricular filling pressure (CVP or PCWP)

41
Q

How do you treat low CO with low CVP?

A

volume resuscitation until a CVP of 10 or PCWP of 15

42
Q

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

A

dobutamine (inotrope)

43
Q

In what situation should anemia be corrected?

A

hgb < 7

44
Q

What side effect of transfusion can decrease VO2?

A

increases blood viscosity and decreases cardiac output as a result

45
Q

To what extent should hypoxia be corrected?

A

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

46
Q

What is the mechanism of increased oxygen utilization in sepsis?

A

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

47
Q

How is decreased oxygen delivery measured?

A

venous O2 sat below 70%

48
Q

At what critical value is venous O2 too low?

A

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

49
Q

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

A

greater than 5%

50
Q

What is considered an abnormal lactate level?

A

above 2 but above 4 impacts morbidity/mortality

51
Q

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

A

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