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Flashcards in 26. Mechanics of Ventilation 2 Deck (9)
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1
Q

How does the helium dilution technique work?

A

Helium/oxygen mix in spirometer
Amount of helium is same in spirometer and when patient inhales to FRC
Gives the equation: FRC=(C1xV1)/C2-V1

2
Q

What happens when a patient tries to breathe in in body plethysmography?

A

Chest and lungs expand
Pressure in lungs decreases
Expanding chest compresses the air inside the chamber
Air volume in the chamber decreases and pressure increases

3
Q

How is FRC calculated in body plethysmography?

A

Using Boyle’s law and measurements from pressure probes inside chamber

4
Q

What is dead space?

A

The volume occupied by gas in the lungs which does not participate in gas exchange

5
Q

What is anatomical dead space?

A

Air in respiratory tract that isn’t in the alveoli

Fowler’s method

6
Q

What is alveolar dead space?

A

Air in alveoli surrounded by pulmonary capillaries without blood flow

7
Q

What is physiological dead space?

A

Total dead space

Bohr’s method

8
Q

How does Fowler’s method work?

A

Pure oxygen is inhaled after FRC exhalation

Continuously exhaled nitrogen is measured

9
Q

How is physiological dead space calculated using Bohr’s method?

A

Measure partial pressures of carbon dioxide in alveoli and expired air