Term
| What are the absolute pressures of the lung? |
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Definition
Mouth pressure: Pm
Alveoloar Pressure: PALV
Body surface pressure: Pbs
Pleural Pressure: Ppl |
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Term
| What are the transpressures? |
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Definition
| Transpulmonary, trans chest wall, transsystem, transairway |
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Term
| What is the equation for transpulmonary pressure? |
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Definition
PL=PALV+Ppl
Alveolar + Pleural |
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Term
| What is the equation for Trans chest wall pressure? |
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Definition
Pcw=Ppl-Pbs
Pleural pressure - body surface pressure |
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Term
| What is the equation for trans respiratory system pressure? |
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Definition
Prs=PAlv-Pbs
Alveolar pressure - body surface pressure |
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Term
| What is the equation for trans airway pressure? |
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Definition
Paw=PAlv - Pm
Alveolar pressure - mouth pressure
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Term
| When you're blowing out is the transairway pressure negative, positive, or zero? |
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Definition
| Positive during expiration |
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Term
| What capacity are you at when transairway pressure is zero? |
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Definition
| FRC functional residual capacity |
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Term
| What are the pressures during the breathing cycle? |
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Definition
Transpulmonary pressure and transairway pressure.
When you exhale transpulmonary pressure is positive, and negative when you inhale. |
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Term
| What is the equation for compilance? |
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Definition
| C=change in volume/change in pressure |
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Term
| What is the golden rule for lung volume and lung pressures? |
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Definition
| There is only one trans pressure per specific lung volume |
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Term
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Definition
| Lung inflates proportionally to pressure difference. Volume is proportional to pressure (linear until a certain point) |
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Term
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Definition
| surface tension is proportional to pressure X radius |
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Term
| If a bubble increases in size, but the amount of surfactant remains the same, what happens to surface tension? |
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Definition
| Surface tension increases |
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Term
| What is critical opening pressure? What are normal values? |
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Definition
The amount of pressure needed to open a collapsed alveolus.
Normal values: 40-55 cm H2O |
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Term
| What are the factors that oppose surface tension and stabilize the lung? |
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Definition
1.Surfactant: a material made of phospholipids which liines ther surface of the terminal lung units (alveoli, alveolar ducts, and respiratory bronchioles)
2.Polyhedral structure: stable in nature
3.Interdependence: architecture of alveolar units promotes mechanical stability. Alveoli are tethered together in such a way that adjoining units help keep each other open. |
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Term
| How do you measure normal compliance, system compliance, and chest wall compliance? |
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Definition
Normal: C= change in volume/change in pressure
System compliance= lung + chest wall compliance
1/total compliance= 1/lung compliance + 1/chest wall compliance |
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Term
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Definition
Which graph has less resistance? What has the bigger endotracheal tube?
R1 |
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Term
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Definition
A way of normalizing compliance. Compliance should be the same in each person as long as not diseased.
Specific compliance= compliance/FRC |
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Term
| Why does the apex have a larger FRC is resting position? |
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Definition
| Because te base is heavier due to weight of the blood and gravity |
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Term
| What are the 3 types of resistance? |
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Definition
- Airway: 80% normal breathing, gas work
- Tissue: 20% can increase if tissue more dense
- Ineterital: negligible (can cause more resistance closer to death due to lung getting heavier)
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Term
| Distribution of Resistance |
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Definition
- 20% nose, pharynx, larynx, trachea
- 60% airways > 2mm cartilaginous
- <20% airways <2mm
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Term
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Definition
- Laminar airflow: friction between tubing wall and gas, driving pressure for laminar flow is influenced by gas viscosity, but not molecular weight or density
- Turbulent flow: more interaction between gas molecules, requires higher pressure
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Term
| Factors that affect Reynold's Number |
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Definition
Reynolds #= diameter*velocity*density/viscosity
Reynolds # greater than 2000 = turbulent flow
Large diameter, large velocity, or large density cause larger #
More viscosity= lower reynolds # |
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Term
| Factors affecting airway resistance. |
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Definition
- Interdependence, amount of air in lung
- Smooth muscle tone: 1. local control (histamine, prostaglandin, high CO2=dilation) 2. Innervation; sympathetic: dilation
- airflow factors: velocity, density, viscosity
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Term
| What trans pressure is the elastic recoil pressure? |
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Definition
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Term
| What are the normal values for resistance? |
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Definition
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Term
| If you decrease the size of a tube, what happens to resistance? |
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Definition
| Resistance increases and more pressure is required |
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Term
| What is the equation for resistance? |
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Definition
| R= Peak pressure-Plateau pressure/change in volume |
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