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What does ventilation deal with?
What are the different pressure gradients?
What is the formula for transrespiratory gradient?
- causes gas to flow into and out of the alveoli during breathing
- Prs = Palv - Pao
What is the formula for transpulmonary gradient?
- equals the pressure difference between the alveoli and pleural space
- PL = Palv - Ppl
What is the formula for transthoracic gradient?
- pressure across the wall - total pressure necessarey to expand or contract the lungs and chest wall together
- PW = PPL - Pbs
What is lung compliance?
distendability of the lung
What is elastance?
resistance to deformation
What is normal compliance in healthy adults?
What does surfactant do to the lungs?
lowers surface tension
Compliance, given value of normal , i.e. .2 and .2, combined = what?
What is Total Compliance?
lung compliance (CL) plus the compliance of the thorax (CT)
What are the two frictional (non elastic) resistances?
tissue viscous and airway resistance
What is Tissue Viscous Resistance?
- impedance of motion caused by displacement of tissues during ventilation
- accounts for 20% of total resistance
What is Airway resistance?
- resistance due to gas flow through the airways
- accounts for about 80% of total resistance
What is compliance?
change in volume / change in pressure
What is airway resistance?
change in pressure / change in flow
Approximately __% of the resistance to gas flow occurs in the nose mouth and large airways
__% of total resistance to flow is due to airways smaller than 2 mm in diameter
What is equal pressure point (EPP)?
the transmural pressure drop finally reaches a point where airway pressure and pleural pressure are the same. After this point the airway can collapse
What is Dynamic Compliance?
- used to assess pressure-volume relationships during breathing (it includes airway resistance).
- dynamic compliance decreases as the respiratory rate increases
Will COPD increase or decrease compliance?
Will Kyphoscoleosis increase or decrease compliance?
What is the most important indication of ventilation?
Does Minute Ventilation include dead space in the calculation?
- Minute ventilation = tidal volume x frequency
Does Alveolar Ventilation inculde dead space in the calculation?
- Alveolar ventilation = tidal volume x frequency - dead space