7 - Spirometry for Obstructive Lung Disease Flashcards

1
Q

What are the components of pulmonary function testing?

A

Spirometry (pre and post bronchodilator)

Lung volumes - nitrogen wash out and plethysmogrophy

Diffusion capacity

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2
Q

What are contraindications to pulmonary function testing?

A
  • Recent abdominal, thoracic, or eye surgery
  • Hemodynamic instability
  • Symptoms of acute severe illness
    • Chest pain, nausea, vimiting, high fever, dyspnea
  • Recent hemoptysis
  • Pneumothorax
  • Recent history of abdominal, thoracic, or cerebral aneurysm
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3
Q

What are patient instructions prior to testing?

A
  • Should NOT drink alcohol for four hours prior to test
  • Should not smoke at least one hour before test
  • Do not eat a large meal two hours prior to test
  • No vigorous exercise 30 min before
  • Should wait at least one month post MI
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4
Q

What equiptment is used in a pulmonary function test?

A
  • Spirometer
  • Respirometer
  • Pneumotachometer
  • Body plethysmograph - body box
  • Diffusion system
  • Gas analysis
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5
Q

What information is used to be obtain prediction values for pulmonary function test?

A
  • Height
  • Weight
  • Age
  • Gender
  • Race/ethnicity

We compare pts values to the values of what we think they should have. You need to see the numbers in the context of what you would expect them to be for their height, weight, age, gender, race/ethnicity.

Smoking would affect their actual valies but not their predictive values.

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6
Q

What are important aspects of performing a pulmonary function test?

A
  • Coaching is important
  • Test is effort dependent
  • Expiration after MAXIMUM inspiration
  • Start as rapidly as possible
  • Continue with maximal effort until there’s no more air to be expelled
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7
Q

What are two criteria for spirograms?

A

Acceptability: free from artifacts such as cough and early termination; good start, satisfactory exhalation

Repeatability: after three acceptable spirograms (are the two largest F VCs within 0.2 L of each other? are the two largest FEV1s within 0.2 L of each other?)

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8
Q

Where are inspiration and expiration on the flow volume loop?

A
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9
Q

How does forced vital capacity change in obstructive and restrictive diseases? What does slow vital capacity (SVC) help with?

A

It’s decreased in both obstructive and restrictive diseases.

Slow vital capacity helps avoid air trapping.

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10
Q

What is the function of forced vital capacity (FVC)? What disease states impact it?

A

Test very sensitive and therefore disease that alter lung mechanisms will affect FVC (forceful exhale).

Impacted by obstructive diseases:

  • COPD - lung tissue is lost and elasticity decreased
  • Chronic bronchitis - mucosal thickening and thick secretions
  • Asthma - bronchoconstriction, mucosal inflammation, edema

Airways narrow and flow resistance increases

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11
Q

What is FEV1? What is it a good indicator of?

A

Forced expiratory volume - maximal volume exhaled during the first second of expiration.

Best indicator of obstructive lung disease.

Best expressed as a percentage of the FVC

  • Should be able to exhale 70% of the vital capacity in the first second
  • Decreased in obstructive disorders because airways are narrowed and there’s increased resistance so air can’t move out as fast
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12
Q

What are the expiratory phase patterns seen in obstructive disease and restrictive disease compared to a normal pattern?

A

Obstructive - higher residual volume, less forceful expiratory phase, and scooped out exhalation. Can’t get the air out fast enough.

Restrictive, less volume but the shape is similar to normal.

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13
Q

Describe the pattern of lung volumes specific to normal people, those with severe empnhysema, and those with pulmonary fibrosis (restrictive)?

A

Young normal: 100% total lung capacity

Emphysema: increased total lung capacity from overexpansion from residual volume increase. Inspiratory capacity hasn’t changed much.

Fibrosis: total lung capacity is decreased

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14
Q

What are the three types of flow loop patterns for large central airways? Describe each and examples of what can cause them?

A
  1. Fixed obstruction - impacts both inhalation and exhalation the same. Exp: tracheal stenosis, goiter.
  2. Variable extrathroacic - outside of the thoracic cavity; inhalation problem. Exp: vocal cord dysfunction.
  3. Variable intrathoracic - inside the chest cavity; exhalation problem. Exp: mainstem bronchis tumor or tracheomalacia.
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15
Q

What are the “three” outcomes from spirometry? What happens to the FEV1/FVC ratio in each?

A

Normal: normal FEV1/FVC ratio; normal FVC

Obstruction: reduced FEV1/FVC ratio

  • less than lower limit of normal (95% confidence interval)
  • GOLD guidelines define as <70%

Restriction: normal FEV1/FVC ratio; reduced FVC (less than 80% of preducted OR < lower limit of normal)

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16
Q

What are the amarican thoracic society (ATS) standards for pulmonary function testing?

A
  1. No coughing; esp during first second of FVC
  2. Good start of test: <5% of FVC exhaled prior to a max expiratory effort
  3. No early termination of expiraton: exhalation time of six seconds or a plateau of 2 seconds
  4. No variable flows: flow rate should be consistent and as fast as possible throughout exhaled VC
  5. Good reproducibility or consistency of efforts: 2 best FVCs and 2 bext FEV1’s should agree within 5% of 100 ml (whichever is greatest)
17
Q

What should you look at first on spirometry interpretation?

A

Look only at FEV1/FVC ratio, FEV1, and FVC

Always look at FEV1/FVC first

18
Q

What should the FEV1/FVC ratio be? What if it’s low what if it’s not low?

A

Must be close to 100% of the predicted to be “normal”. Anything outside the 95% confidence interval is low (lower limit of normal).

  • If it’s NOT low - either normal ventilatory funciton or restrictive processes
  • If ratio is LOW - obstructive process
19
Q

What can cause obstructive ventilatory pattern?

A

Large conducting airways: tumors, foreign bodies

Peripheral airways: asthma and chronic bronchitis

Pulmonary parenchymal disease: emphysematous changes from cigarette smoking

20
Q

If FEV1/FVC ratio is low, what should you do next?

A

The degree of obstruction.

You do this by looking at the percentage of FEV1 (functional expiratory volume). The smaller the percentage of expiratory volume you exhale, the more obstructed you are.

21
Q

When you should assess bronchodilator responsivity? What is a significant response to a bronchodilator?

A
  • For all patients with spirometry showing low FEV1/FVC ratio
  • All patients suspected of asthma or chronic obstructive lung disease.

A significant response to a bronchodilator is shown when the FVC or FEV1 increases at least 12% AND 200 mls

22
Q

What are some restrictive ventilatory defects?

A
  • Interstitial lung disease: sarcoidosis, collagen, vascular diseases, pulmonary fibrosis
  • Pneumonectomy
  • Pleural disease: pleural effusion
  • Chest wall disease: kyphosis, NMJ disorders
  • Extrathoracic condicitons: obesity
23
Q

What changes to FEV1/FVC ratio and FVC occur in restrictive ventilatory defects? What is mild, moderate, and mod-severe restrictive ventilatory defects?

A

Normal FEV1/FVC and decreased FVC

Decreased TLC is the true hallmark of a restrictive ventilatory defect.

  • 70% to LLN of TLC is Mild
  • 60-69% TLC is moderate
  • <60% of TLS is mod-severe
24
Q

How else can you assess restrictive ventrilatory defects other than using TLC?

A
25
Q

What are you thinking if the FEV1/FVC is less than the lower limit of normal? What if it’s above the lower limit of normal?

A

Below: obstruction

Above: ask if FVC is greater than the lower limit of normal.

If yes: normal

If no: suggestive of restrictoin

26
Q

What is learned from pulmonary function testing?

A

It does NOT diagnose a specific disease, just tells you about how they are doing in that moment.

Tells you whether the patient has a ventilatory abnormality at the time of the testing.

The pattern of abnormality.

The degree of ventilatory impairment.

27
Q

What happens to the expiratory flow in obstructive lung defects? What diseases do this?

A

It’s below normal.

Disesases:

  • CF
  • Bronchitis
  • Asthma
  • Bronchiectasis
  • Emphysema
28
Q

What happens to lung volumes in restrictive lung defects? What diseases do this?

A

Lung volumes are reduced.

Diseases:

  • Neuromuscular
  • CV
  • Pulmonary
  • Trauma/chest wall dysfunction
  • Obesity
29
Q

What are the four categories of indications for performing pulmonary function tests?

A

Diagnostic

Monitoring

Disability assessment

Research/public health

30
Q
A