Ventilation

Question 1

1. What are the two components of the chest-wall?

Answer 1

Ribs naturally spring out and lungs naturally recoil inwards-linked by pleura in which they can achieve equilibrium. The components are BONE+MUSCLE+TISSUE and LUNGS

Question 2

2. What is Functional Residual Capacity?

Answer 2

Volume when youre at the end of tidal breathing-when lugns and rib cage are at equilibrium (inwards recoil of lungs and outwards of ribs)

Question 3

3. Describe how the pleural cavity allows the chest wall and the lungs to move in unison.

Answer 3

Pleural cavity is a fixed volume and negative pressure volume-contains a protein rich fluid. Negative pressure of pleural allows for lungs to be pulled with as the ribs expand out and up-lungs get bigger

Question 4

4. How may the fixed volume of the pleural cavity be compromised?

Answer 4

If the chest wall is pierced, then air can fill the pleural cavity-loses stable volume and pleural cavity is compromised-elatic coil takes over and lung collapses. Heamothorax-same happens but slower

Question 5

a. Total Lung Capacity

Answer 5

everything combined-from 0 to total. Max air volume

Question 6

Vital Capacity

Answer 6

total of what can be inspired and expired-and its not TLC because minimal reserve volume TLC-RV

Question 7

c. Functional Residual Capacity

Answer 7

volume of air left after a tidal breath-so respiratory reserve+max of what you can breath out after tidal (ERV): FRC=RV+ERV

Question 8

d. Inspiratory Capacity

Answer 8

how much air you can theoretically take in after equilibrium volume (IRV)-TV+IRV or TLC-FRC

Question 9

e. Reserve volume

Answer 9

Minimal amount of air in the lungs-that cannot be expired completely. TLC-VC

Question 10

f. Expiratory reserve volume

Answer 10

Total amount of air left in the lungs you COULD BREATH OUT after a tidal breath-so FRV-RV

Question 11

g. Inspiratory reserve volume (IRV)

Answer 11

Total amount of air that you can breath AFTER tidal breath-so IC-TV

Question 12

6. Define Tidal Volume.

Answer 12

Nasal breath-amount of inspiration and expiration to meet metabolic demand. End of TV marks the FRV

Question 13

7. Why can’t we totally expel all air from our lungs?

Answer 13

Because of dead space-two types alveolar and physiological. Physio is the bronchi and trachea space-not this. In this case, alveoli cannot be entirely emptied or they will collapse-cannot empty lung totally

Question 14

8. What unit is commonly used when describing lung pressures?

Answer 14

Cm H2O usually

Question 15

9. What are the three main lung pressures involved in respiratory mechanics? Define them.

Answer 15

Between lungs/alveaolar and parietal/intrapleural cavity-trans pulmonary
Between intrapleural and outside chest wall-transmural pressure
Transrespiratory pressure-between alveolar and outside chest wall-tells if air goes in or out

Question 16

10. Give two examples of positive pressure breathing.

Answer 16

Ventilator or CPR-air is pushed in instead of being pulled in

Question 17

11. What is the difference in alveolar pressure between the end of a tidal expiration and the end of tidal inspiration? Explain your answer.

Answer 17

Pressure drops as chest wall expands-alveoli expand as transpulmonary pressure decreases-air goes IN due to negative pressure change-then eventually pressure gradient equalise at end of expiration

Question 18

12. Define Dead Space.

Answer 18

Part of the airway that does not participate in gas exchange-bronchi and some amount of alveoli

Question 19

13. What are the two different types of dead space?

Answer 19

physiological-all that air that goes in cannot be exchanged with blood-in bronchi and trachea-dead space. Alveoli-collpased alveoli, or not perfused, or vital capacity-dead space

Question 20

14. What is the normal physiological dead space of a healthy individual?

Answer 20

Around 150ml

Question 21

15. State two reversible procedures that can change dead space.

Answer 21

Transchaotmy-going through trachea reduces the dead space 5(less trachea)
Ventilator-tube attatched to mouth so INCREASE dead space-cant gas exchange in tube

Question 22

17. Define FVC, FEV1 and FET.

Answer 22

FVC-forced vital capacity, FEV1 is volume of air expelled in 1 second and FET (forced expiratory time-time taken to expel expel all the air from lungs
So a volume time aims to go from tidal breath to vital capacity-forcing it all out. Volume is the FVC, time it takes in FET. In 1 sec you get FEV1; FEV1/FVC gives fraction of how much of the air is expelled in 1sec-around 75% in healthy person

Question 23

16. Explain the chest wall relationship diagram (volume against pressure).

Answer 23

Chest wall naturally wants to expand and lung naturally wants to constrict-and the sum creates a sigmoidal relation of pressure vs volume. At first (from center), small changes in pressure easily acheave large volume changes (up to 6L)-but bigger the volume the harder that get. Hard (energy and effort) and inneficient to try and reduce the pressure below

Question 24

18. How would FRC, FEV and FET values change for the chest wall relationship a) someone with obstructive lung disease, b) someone with restrictive lung disease?

Answer 24

Obstructive (COPD) means FEV1 is lower, FET is higher and FVC is lower-makes a long curve that goes lower (shift down and right). Fraction is LOWER-around 53%
Restrictive- (sarcoidosis)-thorax expantion difficult. FVC is LOWER, FEV can be high (cause airways are fine but less air), FET is usually lower (curve is short and lower-shift down and left). But because less air and fine airways-fraction is HIGHER (around 83%)

Question 25

19. State normal FEV1/FVC values for a normal person, someone with obstructive lung disease and someone with restrictive lung disease.

Answer 25

Healthy around 75, obstructive around 50% and restrictive around 80%

Question 26

20. Describe the general arrangement of a flow-volume loop.

Answer 26

Its flow rate vs total volume. Measured by machine to increase in flow rate is expiration
Start as tidal breath, then inhales to TLC-reaches max left (max volume) and flow is around 0. Then expire as fast as possible-flow rate increases (goes up on curve) and volume drops slightly (left)-1st 60% of volume takes little effort. Then it reaches a peak flow rate as reach residual volume, and the rate goes down–this is where most volume is lost (go down and right). Then inspire again to TLC-goes down and right (volume increase, flow negative (goes in lungs)-starts v fast, then slower (harder to take in)-will then reach back the bottom of expiration curve again, repeat. Different between max tidal and max volume is the IRV, the size of TB is the TV, and from lower TV to min of loop is ERV

Question 27

21. Describe the general protocol of a peak expiratory flow measure

Answer 27

Patient inhales to TLC then exhales as hard as possible into tube-a peak flow meter. Repeat and highest is taken. Then plot that on a normal curve based on age

Question 28

21. Describe how the flow-volume loop changes for a) mild obstructive disease, b) severe obstructive disease and c) restrictive disease.

Answer 28

In obstructive disease, expiration is impeded, but RESIDUAL VOLUME is higher; So loop is naturally more on the left (TV, everything). The first start of expiration (fast upwards) is fine, but the second part is indented (flow rate does down as volume drops intead of going down linearly). The more severe the identation the more severe the disease
Restictive-the volume is very affected but not really the rates-but vital capacity is fine (so starts is same) but TLC is lower-so curve shrinks (narrower), but rest is fine (shape)

Question 29

22. Describe how the flow-volume loop will change for a) variable extrathoracic obstruction, b) variable intrathoracic obstruction and c) fixed airway obstruction.

Answer 29

Extrathoracic obstruction means inspiration will be harder-bottom part flattens out
Intrathoracix obstruction-expiration is harder-inpiration is flat
Fixed-BOTH go flat
INTRA-EXPIRATION, EXTRA-INSPIRATION