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Flashcards in PFTs Deck (24)
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1
Q

what kind of information can you obtain from PFTs?

A
  • how much air volume can be moved in and out of the lungs
  • how fast the air in the lungs can be moved in and out
  • how stiff the lungs and the chest are
  • the diffusion characteristics of the membrane through which the gas moves
  • measurement of how the lungs have responded to tx
2
Q

Indications for PFTs

A
  • screening for lung disease
  • following progression of disease
  • evaluating effectiveness of therapy
  • evaluating before surgery
  • assessment of impairment or disability.
3
Q

What are they types of PFTs?

A
  • spirometry
  • peak flow
  • measurement of lung volumes (body box)
  • quantification of diffusion capacity
  • oxygen uptake –exercise capacity
4
Q

Spirometry

  • measures what?
  • what graphic illustration does this provide?
A
  • Forced expiratory volume in 1 second (FEV1)
  • Forced Vital Capacity (FVC)
  • Flow Volume Loop
5
Q

list some examples of obstructive disease?

A
  • asthma
  • bronchitis
  • excessive mucus plugging
  • foreign object inhalation
  • invasive tumors
  • COPD
6
Q

Can TLC be measured by spirometry?

A

-no, because air remains in the lungs at the end of maximal exhalation.

7
Q

A decrease in lung volumes means what kind of lung disease?

A

restrictive

8
Q

How do you measure Total Lung Capacity?

A
  • Helium dilution
  • Nitrogen Washout
  • Body plethysmography (gold standard)
  • Chest radiograph or HRCT
9
Q

What are some examples of restricitve disorders?

A

Neuromuscular:

  • malnutrition
  • paralysis of diaphragm
  • Myasthenia Gravis
  • Muscular dystrophy
  • Poliomyelitis
  • ALS

Intrinsic Disorders:

  • Sarcoidosis
  • TB
  • Pneuomonectomy
  • Pneumonia
10
Q

What is:

  • FEV1
  • FVC
  • FEF
A

FEV1: forced expiratory volume in 1 sec

FVC: forced vital capacity (volume of air that can be maximally forcefully exhaled)

FEF 25-75%: average forced expiratory flow during the mid portion of the FVC.

11
Q

what test is sensitive for early obstructive airway disease?

A

FEF 25-75%

12
Q

what is PEFR?

A

-the peak expiratory flow rate during expiration, it is the measure of the highest expiratory flow rate during PFT test.

13
Q

Define:

  • TLC
  • VC
  • TV
  • RV
A

TLC: volume in lungs at maximal inspiration

VC: maximum volume expired after a maximum inspiration

TV: the volume inspired and expired during normal breathing

RV: volume left in the lungs after maximal expiration

14
Q

What is the normal and abnormal range of values for FVC and FEV1

A

FVC and FEV1 are over 80% of predicted values.

Abnormal if they are below 70%

15
Q

what would you expect the FEV1/FVC ratio to be with obstructive & restrictive disease?

WHat would you expect to flow volume curve to look like?

A

FEV1/FVC for obstructive disease is less than 70%

FEV1/FVC for restrictive disease is greater than 70%

CURVE:
obstructive- concave, descends more quickly than normal, sharp point

restrictive- smaller version of normal flow.

16
Q

Bronchoprovocation Challenge:

  • when do you perform this test?
  • how does this work?
  • what is a positive test value?
A

When do you perform this:

  • pt who has sx of asthma, but has normal PFTs and no response to bronchodilator therapy
  • patient who experiences sx not usually associated with asthma
  • those who require screening tests for asthma such as scuba divers, military ppl.

How does it work:

  • pre test spirometry for baseline reading
  • give pt an irritant(methacholine) to try to induce bronchoconstriction, repeat spirometry 30 and 90 seconds afterwards

Positive Test value:
-decrease of 20% in FEV1

17
Q

Who cannot have a bronchoprovocation challenge??

A
  • unstable cardiac dz
  • MI in last three mo
  • Stroke in last 3 mo
  • uncontrolled HTN
  • significant bronchospasm already present
  • prenancy/nursing
18
Q

Bronchodilators

  • what can this test determine?
  • if the patient improves 2 of their FVC, FEV1, and FEF 25-75% tests what does this mean?
  • What are the improvement standards? (indicating the dz is reversible)
A
  • determines reversibility of airway obstruction
  • if two of three measurements improve then the pt has a reversible airway obstruction that is responsive to medication.
  • require FEV1 or FVC to increase more than 12% AND more than 200mL in adults or just 12% increase in ages 5-18.
19
Q

WIth restrictive lung disease both FEV1 and FVC present with normal or increased FEV1/FVC ratio, true or false?

A

True!!!

20
Q

Explain the expected FEV1, FEV, FEV1/FVC for someone with restrictive and obstructive disease.

A
Obstructive: 
FEV1: decreased
FVC: decreased 
FEV1/FVC: decreased. 
*ratio less than  70% 
Restrictive: 
FEV1: decreased
FVC: decreased
FEV1/FVC: increased or normal
*Ratio greater than 70%
21
Q
Diffusion Capacity (DLCO)
-useful test for?
A

Useful:

  • determining the degree of emphysema in smokers
  • differentiating chronic bronchitis from emphysema in smokers
  • restrictive disease differentiating interstitial lung disease from restrictive etiologies of disease
  • recurrent PE
  • Pulmonary HTN
  • Disability measurement.
22
Q

How does DLCO work?

A
  • inhale CO and helium
  • hold breath for 10 seconds and then exhale quickly
  • obtain measurement.
  • smoking lowers DLCO
  • CO preferred in this test because its not normally present in alveoli/blood and avidly binds to Hgb
23
Q

What do the results of DLCO mean? Which disease is associated?

A

Low DLCO with obstruction: emphysema or CF in kids

Low DLCO with restriction: pulmonary fibrosis or hypersensitivity pneumonitis

High DLCO: Asthma, polycythemia

24
Q

VO2 Testing

-what does this determine?

A
  • determines how efficient the cardio-resp system is together. (according to jeN)
  • determines patients functional exercise capacity
  • the ability of a person to take in, transport, and use oxygen.