lung physiology 2 (spirometry)

Question 1

define tidal volume

Answer 1

volume of air that enters and leaves with each breath, from a normal quiet inspiration to a normal quiet expiration

Question 2

what is average tidal volume

Answer 2

0.5 L

Question 3

what can cause tidal volume to change (2)

Answer 3

1. it changes with pattern of breathing
2. increases with pregnancy

Question 4

define inspiratory reserve volume

Answer 4

extra volume that can be inspired above tidal volume, from normal quiet inspiration to maximum inspiration

Question 5

average inspiratory reserve volume

Answer 5

2.5 L

Question 6

what does inspiratory reserve volume rely on (3)

Answer 6

• muscle strength
• lung compliance (elastic recoil)
• a normal starting point (end of tidal volume)

Question 7

define expiratory reserve volume

Answer 7

extra volume that can be expired below tidal volume, from normal quiet expiration to maximum expiration

Question 8

average expiratory reserve volume

Answer 8

1.5 L

Question 9

what does expiratory reserve volume rely on (2)

Answer 9

muscle strength

low airway resistance

Question 10

what reduces expiratory reserve volume (3)

Answer 10

• in pregnancy
• obesity
• severe obstruction or proximal (of trachea/bronchi obstruction)

Question 11

define residual volume/reserve volume

Answer 11

volume remaining after maximum expiration

Question 12

average residual volume/reserve volume

Answer 12

1.5 L

Question 13

can residual volume/reserve volume be measured by spirometry

Answer 13

no

Question 14

what are capacities

Answer 14

composed of 2 or more lung volumes.

these are fixed as they do not change with the pattern of breathing

Question 15

what can simple spirometry measure

Answer 15

• tidal volume
• inspiratory reserve volume
  -expiratory reserve volume.

it cannot measure residual volume

Question 16

which values are standardised in spirometry

Answer 16

height - has the greatest influence upon capacities

age

sex

Question 17

describe process of spirometry

Answer 17

1. the subject breathes from a closed circuit over water.
2. the chamber is filled with oxygen and as they breathe, gas increases and reduces the volumes within the circuit.
3. a weight above the chamber changes height with each ventilation according to the circuit volume.
4. its height is recorded with a pen to reflect the volume inspired or expired over time.

Question 18

what is a vitalograph

Answer 18

creates plots of volume against time, using data collected from spirometry tests.

Question 19

what can you measure from a vitalograph (2)

Answer 19

FVC (forced vital capacity)

and

FEV1 (forced expiratory volume in one second)

Question 20

what is FVC (forced vital capacity)

Answer 20

the maximal volume of air that a subject can expel in one maximal expiration from a point of maximal inspiration

Question 21

FEV1 (forced expiratory volume in one second)

Answer 21

the maximal volume of air that a subject can expel in one second from a point of maximal inspiration

Question 22

what is the FEV1/FVC ratio

Answer 22

The proportion of air that can be exhaled in the first second compared to the total volume of air that can be exhaled is important in assessing for possible airway obstruction.

Question 23

what is the flow volume loop

Answer 23

plots flow over volume (showing expiratory flow and inspiratory flow as positive and negative values respectively).

Question 24

what are important factors to consider when assessing flow-volume curves (3)

Answer 24

1. Peak Expiratory Flow Rate (PEFR) – the rate of flow.
2. Vital capacity – the volume expired, calculated from the X-axis.
3. Shape of the curve – ‘spooning’ in obstructive disease, small overall loop in restrictive disease.

Question 25

define spirometry

Answer 25

a method of assessing lung function by measuring the volume of air that the patient is able to expel from the lungs after a maximal inspiration

Question 26

what are typical spirometry findings in obstructive lung disease

Answer 26

• reduced FEV1 (<80% of the predicted normal) - due to increased resistance during expiration
• reduced FVC (but to a lesser extent than FEV1)
• FEV1/FVC ratio reduced (<0.7)

Question 27

examples of obstructive lung disorders

Answer 27

chronic obstructive pulmonary disease, asthma, cystic fibrosis

Question 28

what are typical spirometry findings in restrictive lung disease

Answer 28

• reduced FEV1 (<80% of the predicted normal)
• reduced FVC (<80% of the predicted normal)
• FEV1/FVC ratio normal (>0.7)

Question 29

example of restrictive lung disease

Answer 29

fibrotic lung disease, asbestosis, sarcoidosis

Question 30

what are obstructive lung diseases

Answer 30

conditions that make it hard to exhale all the air in the lungs leading to shortness of breath

because of damage to the lungs or narrowing of the airways inside the lungs, exhaled air comes out more slowly than norma

Question 31

what are restrictive lung diseases

Answer 31

people with restrictive lung disease cannot fully fill their lungs with air. their lungs are restricted from fully expanding

Question 32

what is a peak flow test

Answer 32

a simple measurement of how quickly you can blow air out of your lungs. (exhale)

It’s often used to help diagnose and monitor asthma.

Question 33

what does peak flow test show

Answer 33

can indicate whether your airways are narrowed

could be a sign that you have asthma, although other tests such as spirometry will often be needed to confirm the diagnosis

Question 34

units for peak flow

Answer 34

litres/minute