Pulmonary Function Tests Flashcards

1
Q

What is FEV1?

A
  • Forced expiratory volume in 1 second
  • maximum volume of air that can be forcefully expire within 1 seconds after maximal inspiration
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2
Q

What is FVC?

A
  • Forced vital capacity
  • total amount of air exhaled after maximal inspiration during entire FEV test (over 6 seconds)
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3
Q

What is the FEV1 : FVC?

A

Represents proportion of patient’s FVC that they are able to expire in the first second of forced expiration

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4
Q

What does a FEV1 : FVC ratio of <70% tell us?

A

Obstructive condition

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5
Q

What is tidal volume?

A

Volume of air moving in and out of our lungs at rest

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6
Q

What is inspiratory reserve volume?

A

Additional amount of air that can be inhaled after normal inspiration
(how much more air can be breathed in above TV)

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7
Q

What is expiratory residual volume?

A

Additional amount of air that can be exhaled after normal expiration
(how much more air we can breath out beyond TV)

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8
Q

What is residual volume?

A

Amount of air left in the lungs after maximal forced expiration

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9
Q

What are the 4 lung volumes?

A

Tidal volume
Inspiratory reserve volume
Expiratory reserve volume
Residual volume

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10
Q

What are the 4 lung capacities?

A

Total lung capacity
Vital capacity
Inspiratory capacity
Functional residual capacity

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11
Q

What is inspiratory capacity?
Equation

A

Total volume of air can be inspired
tidal volume + inspiratory reserve volume

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12
Q

What is functional residual capacity?
Equation

A

Volume of air remaining after passive expiration
expiratory reserve volume + residual volume

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13
Q

What is vital capacity?
Equation

A

Volume of air exhaled after maximum inspiration
inspiratory reserve volume + total volume + expiration reserve volume

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14
Q

What is total lung capacity?
Equation

A

Volume of air in lungs after maximum inspiration
IRV + TV + ERV + RV

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15
Q

What are pulmonary function tests used for?

A
  • To measure lung volumes, rate of airflow + gas exchange
  • diagnose patients with respiratory symptoms
  • establish severity + progression of lung disease
  • assess treatment response
  • monitor patients on meds with lung toxicity
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16
Q

Types of pulmonary function tests

A
  • Peak flow rate meter
  • Spirometry
  • (Diffusing capacity for carbon monoxide)
  • (Body plethysmography)
17
Q

What are the contraindications of Spirometry?

A
  • eye surgery: due to ^ pressure in eye during procedure
  • thoracic, abdominal, brain, ENT or vascular surgery
  • lung disease: haemoptysis, pneumothorax, PE
  • ear infection
  • CVS disease - angina, MI, serve HTN
  • aneurysms
  • acute nausea, vomiting or diarrhoea
  • infections control issue: TB, cold, flu
  • confused patients
18
Q

What is peak flow test useful for?

A

Monitoring people with asthma

19
Q

What is peak expiratory flow?

A

Maximum airflow rate attained during forced expiration

20
Q

What is a normal peak expiratory flow value?
What is used to measure it?

A
  • > 80% of predicted average value based on height, gender + age
  • peak flow rate meter
21
Q

What are the two graphs used in Spirometry?

A

Volume time plot
Flow volume loop

22
Q

What is the total lung capacity + residual volume on a flow volume loop?

A
  • total lung capacity: volume of air present in lungs at transition from maximum inspiration to expiration LEFT
  • residual volume: volume air present in lungs at the transition between expiration to inspiration RIGHT
23
Q

How can you use Spirometry to differentiate between asthma and COPD?

A
  • Both obstructive lung disease: FEV1/FVC <70%
  • asthma is reversible but COPD is irreversible
  • give patient a bronchodilator
  • if asthmatic, FEV1 should improve by >12%
  • if COPD, no improvement / <12%
24
Q

How is obstructive lung disease characterised on Spirometry?

A
  • reduced FEV1
  • FEV1:FVC ratio <0.7
  • initial part of curve on volume-time plot rises less steeply
  • coving/scalloping on flow volume loop in expiration
25
Q

How is restrictive lung disease characterised on Spirometry?

A
  • normal or reduced FEV1
  • reduced proportionately FVC
  • FEV1:FVC ratio normal >0.7
  • reduced TLC on flow-volume graph + shrunk in size (smaller volumes)
26
Q

What is diffusing capacity carbon monoxide part of?

A

Peak flow tests

27
Q

What does peak flow meter measure?

A

Maximum airflow rate after maximal inspiration

28
Q

What do diffusing capacity carbon monoxide test do?

A
  • Determines how much O2 travels from alveoli to bloodstream by measuring CO diffusion
  • Provides info on alveolar-capillary membrane
29
Q

What does an abnormal DLCO with normal chest x ray + spirometry suggest?

A

Problem with vascular part of membrane
e.g. idiopathic pulmonary arterial hypertension, choleric thrombo-embolic disease of lung

30
Q

What would investigations of idiopathic pulmonary arterial hypertension show?

A

Normal spirometry
Normal CXR
Abnormal DLCO

31
Q

How do you calculate the peak expiratory flow rate using Spirometry?

A

Maximum slope of curve gradient

32
Q

How can you work out the FVC on a flow-volume graph?

A

RV - TLC
(Between the 2 x intercepts)

33
Q

Flow volume loops in chronic obstructive disease

A

coving/scalloping

34
Q

Flow volume loop in restrictive lung disease

A

Shrunken
Wizard’s hat

35
Q

When is the baseline for peak flow determined?

A

When patient is asymptomatic

36
Q

What factors are use to work out predicated peak flow values?

A

Height
Gender at birth
Age
(Ethnicity)

37
Q

How long can it take for a patient with severe COPD to force all the air out of their lungs in Spirometry?

A

15 seconds

38
Q

What units is flow measured in?

A

L/sec

39
Q

What pattern is seen on flow volume loop in a restrictive lung disease?

A

Wizard’s hat
Shrunken/reduced volume