PH2113 - Lung function & Inhaler technique Flashcards

1
Q

What is a restrictive airway disease?

A

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

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2
Q

What is an obstructive airway disease?

A

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

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3
Q

What is a peak flow meter?

A

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

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4
Q

What is a spirometer?

A

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

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5
Q

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

A

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.

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6
Q

What is the disadvantage of using a spirometer?

A

Costs more than peak flow meters

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7
Q

What is peak expiratory flow rate?

A

Flow rate generated in the first 0.1 seconds of forced expiration

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8
Q

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

A

Flow rate in 0.1 seconds is extrapolated over 1 minute

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9
Q

How is airflow during exhalation decreased?

A

By narrowing or blocking of the airways

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10
Q

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

A

Height
Gender
Ethnicity

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11
Q

How do you use a peak flow meter ?

A

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

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11
Q

How do you use a peak flow meter ?

A

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

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12
Q

What is FEV1 ?

A

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.

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13
Q

What is FVC ?

A

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.

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14
Q

What information is usually required before tests are done ?

A

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

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15
Q

What is the FEV1 / FVC ratio ?

A

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.

16
Q

When does spirometry indicate the presence of an abnormality?

A

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

17
Q

When does spirometry indicate the presence of an obstructive disorder?

A

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

18
Q

When does spirometry indicate the presence of a restrictive disorder?

A
FEV1 reduced (< 80% predicted normal)
FVC reduced (< 80% predicted normal)
FEV1/FVC ratio >0.7
19
Q

What is the aim of an inhaler?

A

To get drug deep into the lung

- obstructive diseases affect cartilage-free airways deep in lung

20
Q

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

A

Airways get narrower as you go down the lungs

  • larger particles get stuck
  • smaller particles breathed out
21
Q

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

A

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

22
Q

Describe the mechanism of an MDI

A

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

23
Q

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

A

20%

24
Q

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

A

80%

25
Q

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

A

5%

  • 4 x less of dose
  • below therapeutic dose so less effective
26
Q

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

A

95%

27
Q

How is an aerosol generated in a DPI?

A
  • 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
28
Q

What are the advantages of a Respimat MDI?

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

- reduces side effects from systemic absorption

29
Q

What are the disadvantages of Respimat MDI?

A

Delivers 1/2 dose to account for increased efficiency

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

30
Q

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

A

Preventers

- not convenient for relievers

31
Q

What are the advantages of using a spacer?

A
  • removes chance of drug landing on tongue

- avoids co-ordination problems

32
Q

What is the correct MDI inhaler technique ?

A
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
33
Q

What is the correct DPI technique for an accuhaler ?

A

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

34
Q

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

A

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

35
Q

What is a common problem with patients that use spacers ?

A

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!

36
Q

What is the correct technique when using a spacer ?

A

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