respiratory pathology

Question 1

what is a spirogram

Answer 1

A tracing of the relationship between maximal expiratory airflow and time

Question 2

what are the 5 components of a spirogram

Answer 2

• forced vital capacity
• residual volume
• total lung capacity
• inspiratory capacity
• functional residual capacity

Question 3

what are 2 ways to test for lung volume

Answer 3

helium dilution (difference in helium conc during inhale and exhale)
body plethysmography (measures pressure change in sealed booth)

Question 4

whats the difference between obstructive and restrictive disorders

Answer 4

obstructive = airway obstruction
restriction = functional reduction in lung volume

Question 5

how can u identify obstructive or restrictive disorders

Answer 5

through spirometry and peak flow

Question 6

what is FEV1

Answer 6

forced expiratory volume in 1 second
(total volume of gas exhaled int he first second of a maximally forced exhalation after maximal inhalation)

Question 7

what can a spirometer measure

Answer 7

FEV1 and FVC (forced vital capacity)

Question 8

how can you measure both FEV1 and FVC

Answer 8

using vane anaemometer

Question 9

what does a vitalograph show

Answer 9

plots volume expired against time (shows plateau)

Question 10

what does a flow-volume curve show

Answer 10

plot volume expired against flow (derived from vitalograph)

Question 11

check iPad notes for graph images

Question 12

what does PEFR stand for and what does it mean

Answer 12

peak expiratory flow rate
- the maximal expiratory flow rate

Question 13

what would show on graph due to obstructive spirometry

Answer 13

FEV1 is lower (flatter gradient)
- but same FVC reached as lung volume is unchanged
- FEV1:FVC ration is lower

Question 14

what is radial traction

Answer 14

the elastic fibres of the surrounding alveoli pull on the walls of small airways and hold them open

Question 15

what can show on graph due to restrictive spirometry

Answer 15

FEV1 middle reduced
- FVC is reduced to
- because both are lowered, FEV1:FVC ration stays similar

Question 16

is pulmonary fibrosis obstructive or restrictive

Answer 16

restrictive

Question 17

is COPD obstructive or restirictive

Answer 17

obstructive (airways collapse and get blocked by mucous walls)

Question 18

what 2 components are part of the work of breathing and what are they

Answer 18

• compliance (expandability of lungs and chest wall)
• resistance (ease which gas flows through conducting airways)

Question 19

decreasing compliance or increasing resistance leads to what?

Answer 19

decrease compliance = restrictive
increasing resistance = obstructive

Question 20

define complience / equation

Answer 20

change in unit volume per unit pressure
compliance = volume/pressure

Question 21

what feature of lungs help passive exhalation

Answer 21

elastic recoil of lungs which is one of the forces that help us passively exhale

Question 22

what are 2 main properties of lung that affect its compliance

Answer 22

1. elastic fibres in lung parenchyma (tissue)
2. water tension in alveoli

Question 23

explain how the water molecules inside alveoli can cause collapsing

Answer 23

• h20 molecules in alveolus have cohesive force
• the leads to inward pressure
• if left unchecked can lead to the collapse of the alveoli, decreased compliance and etc

Question 24

how is prevention of alveoli collapse due to water cohesion taken care of

Answer 24

type 2 pneumocystis in alveoli release surfactants reducing this force

Question 25

the lung has elastic recoil pulling inwards and chest wall has natural pull outwards

Question 26

what is normal intrapleural pressure

Answer 26

negative throughout normal respiratory cycle (755mmHg)
inside = 760mmHg
outside = 760mmHg

Question 27

what happens if theres hole in pleural

Answer 27

pressure equalises and lung collapses (pneumothorax)

Question 28

what is poiseuilles law

Answer 28

flow is proportional to radius^4

Question 29

what causes breath sounds

Answer 29

turbulent airflow going through airway

Question 30

give some examples of meds used to open airway

Answer 30

beta 2 agonist (blue inhaler)
corticosteroids (brown inhaler)
leukotriene receptor antagonist
etc

Question 31

what does IRV/ERV stand for

Answer 31

inspiratory/expiratory reserve volume