Flashcards in Pulmonary Response to CPB- Exam 1 Deck (62):
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
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What is the most common pulmonary complication?
Atelectasis
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How common is atelectasis?
70%
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What happens when lungs with atelectasis are re-expanded and ventilated?
Variable degree remains (microscopic/lobar)
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Atelectasis results in impaired ___________.
Oxygenation
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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
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Atelectasis results in decreased _______________(2).
Lung compliance
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Atelectasis results in increased _________ (2).
Veno-arterial admixure
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What happens to the alveolar-arterial oxygen gradient in atelectasis?
P(A-a)O2 increases
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Factors Contributing to Atelectasis: PREOPERATIVE
Smoking, chronic bronchitis
Obesity
Cardiogenic pulmonary edema
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Factors Contributing to Atelectasis: INTRAOPERATIVE
Anesthesia: reduced surfactant function
passive ventilation
Monotonous ventilator pattern
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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
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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)
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What can anesthesia do to prevent atelectasis?
PEEP
CPAP
OLC (open lung concept)
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Open Lung Concept
a method of ventilation intended to maintain end- expiratory lung volume by increased airway pressure.
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When was "Pump Lung" a big problem?
1950's
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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
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What might cause acute lung injury?
Embolic load
membrane damage from immune response
decreased pulmonary blood flow
hemodilution
elevated pulmonary artery pressure
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What can emboli lead to?
Areas of ventilation/perfusion mismatching
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What can cause the ventilation/perfusion mismatching from emboli?
Aggregated proteins
Disintegrated platelets
Damaged neutrophils
Fibrin
Fat Globules
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What can greatly reduce degenerative lesions in lungs?
Introduction of arterial and cardiotomy filters
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Better the ________-more normal the lungs.
Filtration
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Acute Lung Failure: Membrane Damage
Complement Activation
Vasoactive compounds from PMNs
Oxygen free radicals
Ischemia reperfusion injury
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Where is complement activation found?
Found wherever blood meets foreign surface
Ex. Hemodialysis, leukophoresis
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What functions for fighting invading organisms does complement activation have?
Leukocyte activation
Cytolysis
Opsonization
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Opsonization
makes bacterial cells vulnerable to phagocytosis by attaching various items
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Lungs are ______ from pulmonary circulation during bypass.
Isolated
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(T/F) Lung tissue does not have any metabolic activity on bypass.
False, lung tissue still has metabolic activity
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What is the lung metabolic activity on bypass at 36 C?
11/ ml/min
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What is the lung metabolic activity on bypass at 28 C?
5 to 6 ml/min
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Is bronchial circulation functional on bypass?
Yes
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Complement results in ____________(2).
Localized vasoconstriction
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What is our concern with hemodilution?
Decrease in COP
Movement of fluid into the intracellular space
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Studies indicate the accumulation of pulmonary extravascular water ________ (is/is not) affected by the type of priming solution.
Is not
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Does hemodilution harm the lungs?
No
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Hemodilution prevents impairment of ________________.
Surfactant
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What is a potential cause of pulmonary edema?
Elevated PA Pressure; due to inadequate venting, increased bronchial blood flow
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Elevated PA Pressure can cause
Pulmonary edema
Complement edema
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What triggers acute fulminant bronchospasm on bypass?
Activation C5a
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Fulminant bronchospasm
severe, sudden bronchospasm
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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
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What happens with cold urticaria syndrome?
Release histamine when exposed to cold
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How do you manage bronchospasm?
Stay on bypass or reinitiate bypass
Rest up to anesthesia
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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
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Volatile anesthetics
potent bronchodilators
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What does halothane do?
(Volatile anesthetic)
sensitizes myocardium to catecholamines- risk of tachyarrythmias
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Prevention and Tx of Acute Lung Injury
Blood filtration
Coated circuits
Membrane oxygenators
hemodilution
proper LV venting
Steroids
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What does Blood filtration do?
Leukocyte depletion
Removal of endothelin 1
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What do steroids not affect?
C3a activation or leukocyte elastase release
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Steroids may inhibit what?
Increase in leukotriene B4 and tissue plasminogen activator
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What other problems can steroids cause?
Increased blood loss
low cardiac output syndrome
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What may be more protective than corticosteroids?
Prostaglandins
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What do prostaglandins do?
Inhibits intravascular pulmonary leukocyte aggregation, activation, and free radical production
Hypotensive effect!!
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What does aprotinin inhibit?
Serine proteases (plasmin & kallikrein)
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Aprotinin prevents the activation of what
Kininogen and formation of bradykinin
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What reduces blood usage by preventing platelet aggregation and inhibiting fibrinolysis?
Aprotinin
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What does aprotinin attenuate?
Bradykinin-induced increases in vascular permeability
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Aprotinin results in reduced ________(2) accumulation after bypass.
Lung neutrophil
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Endogenous production of what is reduced post CPB
Nitric Oxide
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What does inhaled nitric oxide do?
Provides potent vasodilation in the pulmonary vasculature
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What is used to treat elevated pulmonary vascular resistance?
Inhaled Nitric oxide
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