Pulmonary Response to CPB- Exam 1 Flashcards
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
What is the most common pulmonary complication?
Atelectasis
How common is atelectasis?
70%
What happens when lungs with atelectasis are re-expanded and ventilated?
Variable degree remains (microscopic/lobar)
Atelectasis results in impaired ___________.
Oxygenation
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
Atelectasis results in decreased _______________(2).
Lung compliance
Atelectasis results in increased _________ (2).
Veno-arterial admixure
What happens to the alveolar-arterial oxygen gradient in atelectasis?
P(A-a)O2 increases
Factors Contributing to Atelectasis: PREOPERATIVE
Smoking, chronic bronchitis
Obesity
Cardiogenic pulmonary edema
Factors Contributing to Atelectasis: INTRAOPERATIVE
Anesthesia: reduced surfactant function
passive ventilation
Monotonous ventilator pattern
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
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)
What can anesthesia do to prevent atelectasis?
PEEP
CPAP
OLC (open lung concept)
Open Lung Concept
a method of ventilation intended to maintain end- expiratory lung volume by increased airway pressure.
When was “Pump Lung” a big problem?
1950’s
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
What might cause acute lung injury?
Embolic load membrane damage from immune response decreased pulmonary blood flow hemodilution elevated pulmonary artery pressure
What can emboli lead to?
Areas of ventilation/perfusion mismatching
What can cause the ventilation/perfusion mismatching from emboli?
Aggregated proteins Disintegrated platelets Damaged neutrophils Fibrin Fat Globules
What can greatly reduce degenerative lesions in lungs?
Introduction of arterial and cardiotomy filters
Better the ________-more normal the lungs.
Filtration
Acute Lung Failure: Membrane Damage
Complement Activation
Vasoactive compounds from PMNs
Oxygen free radicals
Ischemia reperfusion injury
Where is complement activation found?
Found wherever blood meets foreign surface
Ex. Hemodialysis, leukophoresis