PH2113 - Lung function & Inhaler technique

Question 1

What is a restrictive airway disease?

Answer 1

A lung condition where the amount of air that can be inhaled is reduced as the lung becomes less stretchy

Question 2

What is an obstructive airway disease?

Answer 2

A lung condition where the air flow moving in and out of the lungs is reduced

Question 3

What is a peak flow meter?

Answer 3

Measures ability to exhale
Will vary with lung capacity
Use with charts to detect OBSTRUCTIVE disease
Can be used with patients to monitor lung function

Question 4

What is a spirometer?

Answer 4

Simultaneous measurement of flow and capacity
Can be used to diagnose both OBSTRUCTIVE and RESTRICTIVE disease
- gold standard

Question 5

What are two important parameters in lung physiology that are affected by lung disease?

Answer 5

lung capacity – how much air a lung can hold. If the lungs become less compliant, or stretchy, they are unable to expand to hold as much volume. This how restrictive diseases such as pulmonary fibrosis reduce total lung capacity. It should also be noted that lung capacity declines naturally with increasing age.

Air flow. Air flow is determined by the diameter of the lumen in airways. If the diameter is reduced, the resistance to flow is increased with a consequent reduction in air flow. Air flow is affected by obstructive airway diseases such as asthma and COPD.

Question 6

What is the disadvantage of using a spirometer?

Answer 6

Costs more than peak flow meters

Question 7

What is peak expiratory flow rate?

Answer 7

Flow rate generated in the first 0.1 seconds of forced expiration

Question 8

How can you work out Peak expiratory flow rate (PEFR) l/min?

Answer 8

Flow rate in 0.1 seconds is extrapolated over 1 minute

Question 9

How is airflow during exhalation decreased?

Answer 9

By narrowing or blocking of the airways

Question 10

What is the cause of wide variability of PEF values in the population?

Answer 10

Height
Gender
Ethnicity

Question 11

How do you use a peak flow meter ?

Answer 11

Slide the marker down as far as it will go. This sets the meter at zero.
Stand up
Breathe out fully
Take a deep breath in with their mouth open
Place the meter in their mouth with their lips
forming a tight seal around the mouthpiece
Keep their fingers away from the markings
Blow out once as hard and fast as they can
Repeat two more times (resetting the marker
to 0 each time)
Their peak flow is the highest of these 3 readings

Question 12

What is FEV1 ?

Answer 12

FEV1 is the amount of air that can be forcibly exhaled in 1 second.
It is roughly equivalent to peak flow measurements taken with a peak flow meter. It is impacted by airway diameter, but also lung capacity. As with peak flow, the larger the lung capacity, the more air is available to exhale.

Question 13

What is FVC ?

Answer 13

FVC is the forced vital capacity and represents the usable lung capacity. This does not measure the residual capacity that would require special equipment to determine. Similar to FEV1, there are a number of factors that impact on an individual’s lung capacity that have to be taken into account when determining what is ‘normal’. Again, these are programmed into the spirometer.

Question 14

What information is usually required before tests are done ?

Answer 14

Usually, age, gender, height and ethnicity are needed. In addition, smoking status is also acquired as it has an impacts on lung function.

Question 15

What is the FEV1 / FVC ratio ?

Answer 15

the percentage of lung capacity that can be forcible exhaled in one second. This normalises the exhalatory flow to the lung capacity. A ratio of less than 0.7 is indicative or airway obstructive disease.

Question 16

When does spirometry indicate the presence of an abnormality?

Answer 16

FEV1 < 80% predicted normal
FVC < 80% predicted normal
FEV1/FVC ratio <0.7

Question 17

When does spirometry indicate the presence of an obstructive disorder?

Answer 17

FEV1 reduced (< 80% predicted normal)
FVC usually reduced but to a lesser extent than FEV1
FEV1/FVC ratio reduced (<0.7)

Question 18

When does spirometry indicate the presence of a restrictive disorder?

Answer 18

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

Question 19

What is the aim of an inhaler?

Answer 19

To get drug deep into the lung

- obstructive diseases affect cartilage-free airways deep in lung

Question 20

Why must you hold your breath when taking a metered dose inhaler?

Answer 20

Airways get narrower as you go down the lungs

• larger particles get stuck
• smaller particles breathed out

Question 21

What is the major problem when taking medication from a MDI?

Answer 21

There is a 90 degree turn at the back of the throat/top of the trachea
- particles get deposited at the back of the throat if you breath in too fast due to too much momentum

Question 22

Describe the mechanism of an MDI

Answer 22

an aerosol is generated by a pressurised cannister. Activation of this type of device generates a ‘spray’ of aerosolised drug particles

It is simply a pressurised canister containing drug powder that sites on a valve. Depression of the canister results in the delivery of a spray of aerosolised drug through the valve and into the patient’s mouth

Question 23

With good technique, how much of the aerosolised drug from an MDI is deposited in the lung?

Answer 23

20%

Question 24

With good technique, how much of the aerosolised drug from an MDI hits and the back of the throat is swallowed?

Answer 24

80%

Question 25

With poor technique, how much of the aerosolised drug from an MDI is deposited in the lung?

Answer 25

5%

• 4 x less of dose
• below therapeutic dose so less effective

Question 26

With poor technique, how much of the aerosolised drug from an MDI hits and the back of the throat is swallowed?

Answer 26

95%

Question 27

How is an aerosol generated in a DPI?

Answer 27

• aerosol generated by force of inspiration pulling drug out
• drug attached to carrier molecule
• fast inspiration needed to get drug into aerosol
• drug doesn’t separate and hits back of throat

Question 28

What are the advantages of a Respimat MDI?

Answer 28

• increases of % of drug reaching the lung from 20-40%

- reduces side effects from systemic absorption

Question 29

What are the disadvantages of Respimat MDI?

Answer 29

Delivers 1/2 dose to account for increased efficiency

- patients aren’t aware so they doubled dose by mistake

Question 30

Which type of MDI inhaler are spacers useful to use with?

Answer 30

Preventers

- not convenient for relievers

Question 31

What are the advantages of using a spacer?

Answer 31

• removes chance of drug landing on tongue

- avoids co-ordination problems

Question 32

What is the correct MDI inhaler technique ?

Answer 32

Remove cap
Shake device
Breath out
Put open end in the mouth
Start breathing in – normal velocity
Depress trigger
Continue breathing in as much as you can
Hold breath for 10 sec
Breath out
Wait 30 sec before repeating as needed
Replace cap

Question 33

What is the correct DPI technique for an accuhaler ?

Answer 33

Remove cap
Open trigger guard until you hear a click
Move lever until you hear a click
Breath out
Hold device horizontally, put opening in the mouth
Breath in as quickly and as hard as you can
Hold breath for 10 sec
Breath out
Wait 30 sec before repeating as needed
Close trigger guard

Question 34

What is the easiest way to tell apart MDI’s and DPI’s ?

Answer 34

The easiest way to tell them apart is that activation of an MDI always results in a spray whereas DPI activation does not.

Question 35

What is a common problem with patients that use spacers ?

Answer 35

The new style of spacers have an in-built whistle that sounds if the inspiration is too quick
This needs to be explained to patients who often believe they need to inspire sufficiently hard to hear the whistle!

Question 36

What is the correct technique when using a spacer ?

Answer 36

The first, and the one I consider to be preferable, is the one slow deep breath after actuation. The other, is 5 normal, or tidal breaths

Question 37

How do you use a peak flow meter ?

Answer 37

Slide the marker down as far as it will go. This sets the meter at zero.
Stand up
Breathe out fully
Take a deep breath in with their mouth open
Place the meter in their mouth with their lips
forming a tight seal around the mouthpiece
Keep their fingers away from the markings
Blow out once as hard and fast as they can
Repeat two more times (resetting the marker
to 0 each time)
Their peak flow is the highest of these 3 readings