6. Determination of physiologic dead space Flashcards Preview

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Flashcards in 6. Determination of physiologic dead space Deck (19):
1

minute ventilation (Ve)

total volume of gas that entering lungs per minute
Ve tidal colume x respiratory rate

2

alveolar ventilation (Va)

volume gas per unit time that REACHES ALVEOLI
Va = ( tidal colume - physiological dead space) x respiratory rate

3

physiologic dead space equation

tidal volume (Vt) x (arterial pCO2-expired PCO2) / arterial PCO2

4

physiologic dead space definition

anatomic dead space of conducting aiways plus alveolar dead space
volume of inspired air that does not take part in gas exchange

5

alveolar dead space distribution

apex of healthy lung is largest contributor od dead space

6

causes of increased Vital capacity

Acromegaly

7

respiratory rate- normal

12-20 breaths / min

8

physiologic dead space (per breath) normal

150 ml/breath

9

Lung volumes that cannot be measured by spirometry

1. residula volume
2. total lung capacity
3. functional residual capacity

10

pathologic deade space

when part of the repsiratory zone become unable to perfom gas exchange ( ventilated but not perfused)

11

IRV is used during

execise

12

FEV1- definition and normal value

volume f air that can be expired in the first second at a forced maximal expiration

13

FEV1/ FVC - normal value

80%

14

situations that alter FEV1/ FVC

decreased :onstructive lung disease
incresed : restictive lung disease

15

You know a patient's physiologic dead space, expired air CO2, and arterial CO2. Can you calculate their tidal volume (VT)?

Yes, as VD = VT × ([PaCO2 - PECO2]/PaCO2), where PaCO2 = arterial, and PECO2 = expired air

16

A patient's tidal volume is 500 mL, PaCO2 is 50 mmHg, and PECO2 is 35 mmHg. What is the physiologic dead space?

150 mL; VD = 500 mL × ([50 mmHg - 35 mmHg]/50 mmHg)

17

Describe the parts of the airway that contribute to the physiologic dead space.

Conducting airways that contribute to anatomic dead space, and alveolar dead space

18

Which alveolar section of the healthy lung contributes more to physiologic dead space: the apex or the base?

Apex

19

What is the volume of inspired air that does not contribute to gas exchange?

Physiologic dead space, VD