Ventilation and Lung Volumes Flashcards Preview

physiology IV > Ventilation and Lung Volumes > Flashcards

Flashcards in Ventilation and Lung Volumes Deck (37):
1

What effect does increasing lung compliance have on FRC?

It increases FRC
-not able to expel as much air

2

What happens to lung compliance with age?

it decreases

3

What is total lung capacity? What is the normal value?

max volume of gas that the lungs can contain
6-7 L

4

What is the tidal volume? What is the normal value?

Volume of gas which flows into and then out with each breath

-500-600 mL

5

How can tidal volume be increased?

exercise

6

can tidal volume be measured by a spirometer?

Yes

7

What is inspiratory reserve volume?

max volume of gas that can be inhaled from end-tidal inspiratory position

8

What is expiratory reserve volume?

-volume of gas that can be exhaled from end-tidal expiratory position

9

What is residual volume?

volume of gas contained in the lungs after max force of expiration
-can't be exhaled

10

What is vital capacity?

-max volume of gas that can be exhaled after normal inspiration

11

What is inspiratory reserve capacity? (IC)

max volume of gas that can be inhaled from resting expiratory position

12

What is the formula for vital capacity ?

VC= IRV +Vt + ERV = TLC- RV

13

What is the formula for IC?

IC= VT+IRV = TLC - FRC

14

What is functional residual capacity?

Volume of gas in the lungs after normal expiration
-when diaphragm and chest muscles are relaxed

15

Can FRC be measured by a spirometer?

NO - it includes RV

16

What is the ultimate goal of using a N2 washout?

You want to measure FRC
- can't measure with a spirometer
-this value is a good indicator of obstructive or restrictive diseases

17

What are the steps involved in N2 washout ?

1. subject breathes normal air
-N2 fraction is measured

2. at the end of eupneic breathing - lung is at FRC and subject breathes in 100% O2
-for at least 7 minutes
-washes out all N2 from the lung

3. expired gas is collected in spirometer

18

What is the issue with using N2 washout to record FRC?

- if there are regions in the lung with trapped air, this volume won't be measured
-FRC is underestimated

19

do we have to know the FRC equation for N2 washout, or the pletysmograph equation ????

not sure, making this flash card to remind us to memorize them if need be

20

What is a plethysmograph?

a gas-tight chamber in which a patient sits in and breathes through a tube leading to outside
-used to measure FRC

21

As a patient expires against a pressure transducer with a closed valve in a pletysmograph, what happens to their lung volume and P?

-the volume of the lung is compressed
-the P of the lung is raised

22

Since the chamber is gas tight, what happens to the air in the box outside the subject's body as they breathe air to the outside?

-the air will expand
-this change in volume is exactly equal to the amount of compression of air in the lungs

23

What is the amount of dead space in mL approximated as ?

equal to the subject's weight in pounds

24

What is total ventilation equal to?

Dead space ventilation plus alveolar ventilation

25

Hypoventilation results in what two consequences?

1. alveolar hypercapnea - inc PACO2
2. hypoxia - dec PAO2

26

Hyperventilation results in what two consequences?

1. alveolar hypocapnea - dec PACO2
2. hyperoxia - inc PAO2

27

Increasing oxygen consumption, has what effect on alveolar oxygen?

decreases it

28

What does R mean in the equation:
PAO2=PlungO2-PACO2/R

-ratio of O2 consumption to production

29

Vt is about what percentage of TLC?

only about 10%
-volume of air going into and out of the lung with each breath = small fraction of air in the lung

30

About by how much do the PO2 and PCO2 oscillate by in alveoli during eupnea?

1-2 mmHg

31

Why does the PO2 first decrease when you first inspire?

O2 is going into blood when air is going through the dead space

32

What is a single breath analysis of dead space?

-subject inspires air containing neglible CO2 and then exhales into a spirometer
-fraction of CO2 is measured
(contains CO2 from the body)

33

As the subject exhales, what does the FECO2 rise to and plateau at?

5%

34

Why when the patient first exhale, does the first gas contain negligibly low CO2?

gas comes from the anatomic dead space

35

What does the time of the midpoint of the rise of FECO2 correspond to?

the time at which all of the dead space air would be expired
-if there was a sharp boundary btwn dead space gas and alveolar gas

36

What does the alveolar ventilation equation predict?

It describes the dependence of alveolar and arterial Pco2 on alveolar ventilation

37

What does the alveolar gas equation predict?

Predicts the alveolar Po2, based on the he alveolar Pco2