Flashcards in Concepts in V and Q Deck (17):

1

## Conducting zone

### Nose, nasopharynx, larynx, trachea, bronchi, terminal bronchioles. Warm, humidify, filter air.

2

## Respiratory Zone

### Respiratory bronchioles, alveolar ducts, alveolar sacs. Gas exchange and surfactant production.

3

## Anatomic dead space

### The volume of the conducting zone. Usually 150 ml.

4

## Physiologic dead space

### The total volume of the lungs that does not participate in gas exchange.

5

## How is dead space measured? Equation?

###
Compare expired PCO2 and PA/aCO2. PECO2 should be lower by a dilution factor because it mixes with dead space air that only has O2.

Equation: Vd=Vt x [(PaCO2-PECO2)/PaCO2]

6

## What does a Vd/Vt of 1 mean? Of zero?

### 1= entire lung is dead space. 0= there is no dead space.

7

## Minute ventilation equation

### V= Vt X RR, about 6 L/min

8

## Alveolar Ventilation Equation

###
Va = (Vt-Vd) X RR

9

## Partial pressure of alveolar CO2 equation

### PACO2 = (VCO2 x K)/Va

10

## Alveolar Gas Equation

###
Describes the relationship between PACO2 and PAO2.

PAO2 = PIO2 - (PCO2/R)

R usually = 0.8

11

## What happens to PACO2 and PAO2 is alveolar ventilation is halved?

### PACO2 doubles, but PO2 is more than halved.

12

## Which is more constant throughout the body and in alveoli? PO2 or PCO2?

### PCO2 is much more constant.

13

## Regional Differences in Ventilation

### Higher Q at the bottom because weight of lungs squeezes air out. Lower Q at the top.

14

## V/Q ratio of a shunt?

### V/Q=0, there's perfusion without ventilation. Bypasses the alveoli.

15

## V/Q ratio of dead space?

### V/Q is infinity. There's ventilation without perfusion.

16

## Normal V/Q?

### 0.8

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