Intrathoracic Vascular Pressures Flashcards
List some of the intrathoracic vascular pressures
PA CVP R. Atrial R. Ventricular L. Atrial
Define compliance
Change in volume / change in pressure
How do you calculate lung compliance?
Vt / P
How do you calculate thoracic compliance?
Vt / P pleural
How do you calculate total compliance?
Vt / Paw
What are the normal values for lung compliance, thoracic compliance, and total compliance?
CL= 200 mL/cmH2O CT= 200 mL/cmH2O CLT= 100 mL/cmH2O**
How do lung, thoracic, and total compliance mathematically relate to each other?
Ohm’s law
Lungs and chest wall in series
Lungs in parallel with each other
What is the difference between dynamic compliance and static compliance?
Dynamic compliance is measured while the patient is breathing
Static compliance is measured at equilibrium and is easily reproduced
When during a spontaneous respiratory cycle do you make hemodynamic measurements?
End expiration
Why do you make hemodynamic measurements during end expiration of a ventilatory cycle?
Because the patient spends the most time in expiration
Also, It is the point at which Long’s tendency to collapse and Chestwall’s tendency to expand our equal
Define transmural filling pressure
Pressure across the vessel wall
Normal= 5-8
If the lung compliance and thoracic compliance are normal what is the percent transmission of IVP?
50%
If the lung compliance is normal and the thoracic compliance is increased what is the percent transmission for IVP?
<50%
What is an example of when the lung compliance would be normal but the thoracic compliance would be increased?
Thoracotomy or laparotomy
When the lung compliance is normal in the thoracic compliance is decreased what is the percent transmission of IVP?
> 50%
What is an example of when the lung compliance would be normal in the thoracic compliance would be decreased?
Stiffer chest wall (swollen neonate ex)
When the lung compliance is Increased in the thoracic compliance is normal what is the percent transmission of IVP?
> 50%
What is an example of when the long compliance would be increased but the thoracic compliance would be normal?
Emphysema
When the lung compliance is decreased in the thoracic compliance is normal what is the percent transmission of IVP?
<50%
What is an example of a condition where the lung compliance would be decreased in the thoracic compliance would be normal?
Fibrosis
When the lung compliance is increased in the thoracic compliance is decreased what is the percent transmission of IVP?
> > 50%
What is an example of a condition where the lung compliance would be increased in the thoracic compliance would be decreased?
Advanced emphysema
How would you change your ventilation settings in a patient with increased lung compliance and decreased thoracic compliance?
Decrease inspiratory pressure
Increase expiratory time
Decrease flows
Winlong compliance is decreased and thoracic compliance is increased what is the percent transmission of IVP?
«50%
What happens to the percent transmission of IVP when both lung compliance and thoracic compliance are increased together or decreased together?
Depends
What happens to lung compliance and thoracic compliance in infant respiratory distress syndrome (IRDS)?
Both decreased
