Pulmonary Response to CPB- Exam 1 Flashcards Preview

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1

Atelectasis

A complete or partial collapse of a lung or a lobe of the lung; develops when the alveoli become deflated and don't inflate properly

2

What is the most common pulmonary complication?

Atelectasis

3

How common is atelectasis?

70%

4

What happens when lungs with atelectasis are re-expanded and ventilated?

Variable degree remains (microscopic/lobar)

5

Atelectasis results in impaired ___________.

Oxygenation

6

Atelectasis results in decreased ______________(3). What percent after anesthesia? What percent after CPB?

Functional Residual Capacity; decreased by 20% after general anesthesia, by 40-50% after CPB

7

Atelectasis results in decreased _______________(2).

Lung compliance

8

Atelectasis results in increased _________ (2).

Veno-arterial admixure

9

What happens to the alveolar-arterial oxygen gradient in atelectasis?

P(A-a)O2 increases

10

Factors Contributing to Atelectasis: PREOPERATIVE

Smoking, chronic bronchitis
Obesity
Cardiogenic pulmonary edema

11

Factors Contributing to Atelectasis: INTRAOPERATIVE

Anesthesia: reduced surfactant function
passive ventilation
Monotonous ventilator pattern

12

Factors Contributing to Alelectasis: BYPASS

Surfactant inhibition
Plasma, lung distention, lung ischemia
Increased extravascular lung water ( complement activation)
heart rests on immobile left lower lobe
Open pleural cavity- accumulation of blood and fluid

13

What can we do to prevent atelectasis?

Decreased complement activation
Reduced chances of edema
Anesthesia has more control (i.e. how lungs are deflated and re-inflated)

14

What can anesthesia do to prevent atelectasis?

PEEP
CPAP
OLC (open lung concept)

15

Open Lung Concept

a method of ventilation intended to maintain end- expiratory lung volume by increased airway pressure.

16

When was "Pump Lung" a big problem?

1950's

17

What is "Pump Lung"

Acute respiratory failure
Lungs diffusely congested
Intra-alveolar and interstitial edema
Hemorrhagic atelectasis
Vessel lumina full of neutrophils
Diffuse swelling of endothelial cells

18

What might cause acute lung injury?

Embolic load
membrane damage from immune response
decreased pulmonary blood flow
hemodilution
elevated pulmonary artery pressure

19

What can emboli lead to?

Areas of ventilation/perfusion mismatching

20

What can cause the ventilation/perfusion mismatching from emboli?

Aggregated proteins
Disintegrated platelets
Damaged neutrophils
Fibrin
Fat Globules

21

What can greatly reduce degenerative lesions in lungs?

Introduction of arterial and cardiotomy filters

22

Better the ________-more normal the lungs.

Filtration

23

Acute Lung Failure: Membrane Damage

Complement Activation
Vasoactive compounds from PMNs
Oxygen free radicals
Ischemia reperfusion injury

24

Where is complement activation found?

Found wherever blood meets foreign surface
Ex. Hemodialysis, leukophoresis

25

What functions for fighting invading organisms does complement activation have?

Leukocyte activation
Cytolysis
Opsonization

26

Opsonization

makes bacterial cells vulnerable to phagocytosis by attaching various items

27

Lungs are ______ from pulmonary circulation during bypass.

Isolated

28

(T/F) Lung tissue does not have any metabolic activity on bypass.

False, lung tissue still has metabolic activity

29

What is the lung metabolic activity on bypass at 36 C?

11/ ml/min

30

What is the lung metabolic activity on bypass at 28 C?

5 to 6 ml/min

31

Is bronchial circulation functional on bypass?

Yes

32

Complement results in ____________(2).

Localized vasoconstriction

33

What is our concern with hemodilution?

Decrease in COP
Movement of fluid into the intracellular space

34

Studies indicate the accumulation of pulmonary extravascular water ________ (is/is not) affected by the type of priming solution.

Is not

35

Does hemodilution harm the lungs?

No

36

Hemodilution prevents impairment of ________________.

Surfactant

37

What is a potential cause of pulmonary edema?

Elevated PA Pressure; due to inadequate venting, increased bronchial blood flow

38

Elevated PA Pressure can cause

Pulmonary edema
Complement edema

39

What triggers acute fulminant bronchospasm on bypass?

Activation C5a

40

Fulminant bronchospasm

severe, sudden bronchospasm

41

What triggers acute bronchospasm on bypass?

Cold urticaria syndrome
Preexisting bronchospastic disease
instrumentation
secretions
cold anesthetic gas in patients with hyperactive airways
allergic reactions to antibiotics or protamine
drugs that induce histamine release

42

What happens with cold urticaria syndrome?

Release histamine when exposed to cold

43

How do you manage bronchospasm?

Stay on bypass or reinitiate bypass
Rest up to anesthesia

44

What can anesthesia manage bronchospasm?

Beta selective agonists directly into endotrachial tube (albuterol, metaproterenol)
Small iV bolusis of epi followed by continuous low dose infusion
IV lidocaine given to decrease airway hyperactivity
volatile anesthetic agnets can be given through pump

45

Volatile anesthetics

potent bronchodilators

46

What does halothane do?

(Volatile anesthetic)
sensitizes myocardium to catecholamines- risk of tachyarrythmias

47

Prevention and Tx of Acute Lung Injury

Blood filtration
Coated circuits
Membrane oxygenators
hemodilution
proper LV venting
Steroids

48

What does Blood filtration do?

Leukocyte depletion
Removal of endothelin 1

49

What do steroids not affect?

C3a activation or leukocyte elastase release

50

Steroids may inhibit what?

Increase in leukotriene B4 and tissue plasminogen activator

51

What other problems can steroids cause?

Increased blood loss
low cardiac output syndrome

52

What may be more protective than corticosteroids?

Prostaglandins

53

What do prostaglandins do?

Inhibits intravascular pulmonary leukocyte aggregation, activation, and free radical production

Hypotensive effect!!

54

What does aprotinin inhibit?

Serine proteases (plasmin & kallikrein)

55

Aprotinin prevents the activation of what

Kininogen and formation of bradykinin

56

What reduces blood usage by preventing platelet aggregation and inhibiting fibrinolysis?

Aprotinin

57

What does aprotinin attenuate?

Bradykinin-induced increases in vascular permeability

58

Aprotinin results in reduced ________(2) accumulation after bypass.

Lung neutrophil

59

Endogenous production of what is reduced post CPB

Nitric Oxide

60

What does inhaled nitric oxide do?

Provides potent vasodilation in the pulmonary vasculature

61

What is used to treat elevated pulmonary vascular resistance?

Inhaled Nitric oxide

62

What other effects does inhaled nitric oxide have?

Some anti-inflammatory properties
-Decreases IL-8
-Attenuates neutrophil adhesion and migration
-Attenuates apoptosis in lungs