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YEAR 2: Respiratory Disease (MGEM2013 UNUK) (SPR1 23-24) > Lung function tests > Flashcards

Lung function tests Flashcards

1
Q

what is peak expiratory flow?

A

maximal speed of airflow as the patient exhales in L/min

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2
Q

what does (1) increase or (2) decrease in PEF value reveal

A

increase:

  • lung function is better

decrease:

  • lung function has gotten worse
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3
Q

what is FVC (forced vital capacity)

A

maximal amount of air (L) that a patient can forcibly echale after taking in maximal inhalation

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4
Q

what does a spirometer record and what can it generate

A
  • records:volume of air that is breathed in and out
  • generates: tracings of air flow called a pneumotachograph
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5
Q

what 3 things can tracings on a pneumotachograph allow you to observe

A
  • tidal volume
  • vital capacity
  • flow rate of air movement
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6
Q

what is always bigger, FVCstanding or FVCseated

A

FVCstanding is always larger than FVseated

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7
Q

what 2 things can high intrathoracic pressure result in and what can this lead to when observing FVCstanding of patients?

A
  • reduced cardiac output
  • reduced cerebral blood flow

can lead to patients becoming unsteady on their feet in FVCstanding patients

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8
Q

outline 4 steps of how a spirometer works

Think:
1. water seal
2. Pressure and jar
3. Pen
4. Relationship to pen and volume breathed in and out

A
  1. expired gas passes into water seal
  2. increased pressure causes jar to rise
  3. movement is then transmitted to a pen
  4. pen movement is proportional to volume breathed in and out
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9
Q

how is inspiration displayed as on a spirometer pen trace?

A

it is displayed as an upward deflection

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10
Q

how is expiration displayed as on a spirometer pen trace?

A

it is displayed as an downward deflection

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11
Q

how do you calculate inspiratory capacity from a spirogram?

A

Tidal volume (Vt) + Inspiratory reserve volume (IRV)

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12
Q

how do you calculate functional residual capacity from a spirogram?

A

Expiratory reserve volume (ERV) + residual volume (RV)

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13
Q

what 5 things can forced flow volume measurements show us (FVC and FEV1)

think:
- blowing out
- expelling air from lungs
- treatment
- diases
- age/growth

A

can show us:

  • how much air can the subject blow out
  • how fast the air is expelled from lungs
  • response to treatment
  • progression of disease
  • change with age/growth
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14
Q

what 2 things reduce how much air a subject can blow out in forced flow-volume measurements

For second part think narrowing and closure

A
  • restrictive disorders
  • airwary narrowing precipitating early airway closure (asthma or CF)
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15
Q

what can a pattern change in flow-volume curve indicate?

A

can indicate site of obstruction

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16
Q
  1. what is FEV1 on spirogram
A

maximal volume exhaled in the first second

17
Q

what are the 3 typical patterns of Forced flow-volume measurements in obstructive airway diseases and give a reason for why

think FVC, FEV1 and FEV1/FVC ratio

for the reason think speed of air

A
  • FVC nearly normal
  • FEV1 markedly reduced
  • FEV1/FVC ratio is less than 70%

1 reason why is that narrowed airways reduces the speed at which air can be breathed out

18
Q

what obstructive disease does it indicate someone has if there is improvement of a volume-time graph curve, towards the normal, after treatment with a bronchodilator?

A

it indicates the person has Asthma

19
Q

what obstructive disease does it indicate someone has if there is NO improvement on a volume-time graph curve after treatment with a bronchodilator?

A

it indicates the person has COPD

20
Q

what are the 3 typical patterns of Forced flow-volume measurements in restrictive airway diseases

think FVC, FEV1 and FEV1/FVC ratio

A
  • low FVC
  • low FEV1 but is proportionality to FVC is normal
  • FEV1/FVC ratio is ≥ 70% (elevated)
21
Q

why is there low FVC in restrictive diseases like lung fibrosis?

A

because lungs are stiff so cannot expand adequately

22
Q

what does the width of a volume flow loop show?

A
  • shows the vital capacity/forced vital capacity
23
Q

what does the rapid rise at the beginning of the expiratory portion of the flow volume loop show?

A

shows large airway movement

24
Q

what type of airway movement does the sloped section of the expiratory section of a flow-volume loop show?

A

shows small airway movement

25
Q

outline the differences in a flow volume loop between someone with an obstructive disease (e.g COPD, asthma, tracheal-stenosis) and a normal flow volume loop

hint: think:

  • expiration line
  • think what does this look like if the small airways are obstructed
  • think waht this line looks like if the large airways are obstructed
A

NORMAL flow-volume loop:
- relatively linear expiratory slope
- normal/expected steep rise in the inital portion of the expiration line

OBSTRUCTIVE disease flow-volume loop:

  • if **smaller/lower airways ** are obstructed, there is a smaller angle or caving in of the usually linear expiratory slope on the flow-volume loop
  • if upper/large airways are obstructed, initial portion of expiration line can also have shorter steep line.
26
Q

what is the physiological reason for why flow-volume loops are narrowed in restrictive lung diseases

A
  • This is because the lungs suffering from restrictive diseases are not able to expand to the same volume as healthy lungs, meaning the Vital capacity/Forced vital capacity is reduced, thus narrowing the loop.
26
Q

outline the differences in a flow volume loop between someone with a restrictive disease (e.g lung fibrosis, interstitial lung disease) and a normal flow volume loop

hint:
- difference lies in the width of the flow volume loop

A

NORMAL flow-volume loop:
- relatively linear expiratory slope
- normal/expected steep rise in the inital portion of the expiration line
- normal width of the flow-volume loop, meaning normal VC/FVC

RESTRICTIVE disease flow-volume loop:
- relatively linear expiratory slope
- normal steep rise in initial portion of expiration line

  • Difference is that there is low VC/FVC, therefore the width of the flow-volume loop is lower, narrowing the loop
27
Q

what is the physiological reason for why flow-volume loops have a shorter steep line and/or caved in slopes in obstructive diseases?

A

this is because the obstruction to the upper and/or lower airways reduces the speed at which air in the airways can be breathed out.

YEAR 2: Respiratory Disease (MGEM2013 UNUK) (SPR1 23-24) (39 decks)

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