Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Week 8 - Respiratory > Lung Function Testing > Flashcards

Lung Function Testing Flashcards

1
Q

Why do we measure lung function? [7]

A
  1. Evaluation of the breathless patient
  2. Screening for COPD or occupational lung disease
  3. Lung cancer- fitness for treatment
  4. Pre-operative assessment
  5. Disease progression and treatment response
  6. Monitoring of drug treatment toxic to the lungs
  7. Pulmonary complications of systemic disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name the lung function tests [8]

A
  1. Peak flow oximetry
  2. Spirometry
  3. Transfer factor
  4. Lung volumes
  5. Blood gases
  6. Bronchial provocation testing
  7. Respiratory muscle function
  8. Exercise testing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define spirometry and how to instruct the patient to carry out the procedure [2]

A
  1. Definition
    • Forced expiratory manoeuvre from total lung capacity followed by a full inspiration, which the best of 3 acceptable attempts (within 5%) recorded
  2. “take a big breath in as far as you can and blow out as hard as you can for as long as possible- then take a big breath all the way in”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the pitfalls to spirometry? [4]

A
  1. Appropriately trained technician needed
  2. Effort and technique dependent
  3. Patient frailty
  4. Pain, patient too unwell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define the following on this graph:

  1. IRV
  2. VT
  3. ERV
  4. RV
  5. VC
  6. FRC
  7. TLC
  8. FVC
A
  1. IRV = inspiratory respiratory volume (the volume of air in full inspiration)
  2. VT = tidal volume (normal, relaxed breathing)
  3. ERV = expiratory respiratory volume (the volume of air in full expiration)
  4. RV = residual volume (volume of air remaining in lungs after expiration)
  5. VC = vital capacity = the amount of air expired from a fully inflated lung
    • VT + IRV + ERV
  6. FRC = functional residual capacity = the amount of air remaining in the lungs after a normal breath
    • ERV + RV
  7. TLC = total lung capacity = sum of all lung volumes
  8. FVC is similar to VC, just that it is the maximal amount of air expired forcefully after breathing in and out fully
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is FEV1 and FVC and what is the normal FEV1/FVC ratio? If the FEV1/FVC ratio is reduced, what does this indicate? [4]

A
  1. FEV1 = forced expiratory volume in one second
    • the total volume of air expired forcefully in the first second
  2. FVC = forced vital capacity
    • The total volume of air expired altogether
  3. Work out the FEV1/FVC ratio
    • E.g. 3 litres/4 litres
    • = >70% (normal)
  4. If the FEV1/FVC ratio is less than 70%, this is suggestive of an obstructive pattern of disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe how to interpret a flow/volume loop

A
  1. Plotting flow rates against expired volume shows the site of airflow limitation within the lung.
  2. At the start of expiration from TLC, maximum resistance is from the large airways, and this affects the flow rate for the first 25% of the curve.
  3. As air is exhaled, lung volume reduces and the flow rate becomes dependent on the resistance of smaller airways.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 conditions that are classified as obstructive lung disease and what is the typical FEV1/FVC ratio of these conditions? [3]

A
  1. asthma
  2. COPD
  3. ratio <70%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Severity of COPD stratified by %predicted FEV1. Classify the following based on predicted FEV1:

  1. mild COPD [1]
  2. moderate COPD [1]
  3. severe COPD [1]
  4. very severe COPD [1]
A
  1. mild >80%
  2. mod 50-80%,
  3. severe 30-50%,
  4. very severe <30%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the abnormality seen on the flow/volume loop in COPD [3]

A

In COPD, where the disease mainly affects the smaller airways, expiratory flow rates at 50% or 25% of the vital capacity are disproportionately reduced when compared with flow rates at larger lung volumes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe how reversibility testing in spirometry is carried out and state what results are suggestive of asthma [5]

A
  1. Spirometry measurement is taken
  2. Nebulised or inhaled salbutamol is given
  3. 15 minutes after salbutamol, another spirometry measurement is taken
  4. 15% and 400ml reversibility in FEV1 → suggestive of asthma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the other investigations done for asthma, other than salbutamol reversibility testing spirometry? [3]

A
  1. peak expiratory flow rate (PEFR) testing
  2. Bronchial provocation
  3. Spirometry before and after trial of inhaled/oral corticosteroid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the characteristics of restrictive lung disease on lung function tests? [3]

A
  1. FEV1 and FVC reduced
  2. FEV1/FVC ratio >70%
  3. Lungs look a bit smaller in flow/volume loop
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the causes of restrictive spirometry? [6]

A
  1. Interstitial lung disease (stiff lungs)
  2. Kyphoscoliosis/chest wall abnormality
  3. Previous pneumonectomy
  4. Neuromuscular disease
  5. Obesity
  6. Poor effort/technique
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe how to interpret spirometry (idiot’s guide) [6]

A
  1. Look at FEV1/FVC ratio
    • If <70% = obstruction
  2. If obstructed, look at % predicted FEV1 (severity) and any reversibility
    • to determine whether COPD vs asthma
  3. If FEV1/FEV ratio normal, look at % predicted FVC
    • if %predicted FVC = low → suggests restrictive abnormality

Can also get mixed picture, e.g. obesity and COPD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you measure transfer factor (TLCO, KCO, DLCO)? [3]

A
  1. Patient takes a single breath of a very small concentration of carbon monoxide (CO)
    • CO has very high affinity to Hb so is taken up very quickly in the alveoli
  2. Measure concentration in expired gas to derive uptake in the lungs
17
Q

What is transfer factor affected by? [4]

A
  1. Alveolar surface area
  2. Pulmonary capillary blood volume
  3. Haemoglobin concentration
  4. Ventilation perfusion mismatch
18
Q

Transfer factor will be reduced in which conditions? [4]

A
  1. Emphysema
  2. Interstitial lung disease
  3. Pulmonary vascular disease
  4. Anaemia (increased in polycythaemia)
    • → there’s less haemoglobin to take up in CO
19
Q

What are the 2 methods of measuring lung volumes if you cannot measure residual volume using spirometry? [2]

A
  1. Helium dilution
    • (inspire known quantity of inert gas)
  2. Body plethysmography
    • respiratory manoevures in a sealed box lead to changes in air pressure- can derive lung volumes
20
Q

How does lung volumes (incl. RV & TLC) get affected in…?

  1. restrictive lung disease [1]
  2. obstructive lung disease [2]
A
  1. Restrictive lung disease
    • lung volumes are reduced
  2. Obstructive lung disease
    • increased residual volume (RV)
    • increased residual volume/total lung capacity (RV/TLC) ratio
21
Q

What is oximetry and what factors does it depend on? [3]

A
  1. Non-invasive measurement of saturation of haemoglobin by oxygen
  2. Depends on:
    • oxyhaemoglobin and deoxyhaemoglobin absorbing infrared light differently
    • adequate perfusion
22
Q

What are the main causes of hypoxaemia? [4]

A
  1. Hypoventilation (e.g. drugs, neuromuscular disease)
  2. Ventilation/perfusion mismatch (e.g. COPD, pneumonia)
  3. Shunt (e.g. congenital heart disease)
  4. Low inspired oxygen (altitude, flight)
23
Q

What is ventilation/perfusion mismatch and how does it cause hypoxaemia? [2]

A
  1. Areas of lung that are perfused but not well ventilated (e.g. pneumonic consolidation)
  2. Mixing of blood from poorly ventilated and well ventilated parts of the lung causes hypoxaemia
24
Q

How do you interpret blood gas results from a respiratory perspective? [3]

A
  1. Always look at the pO2 first
    • Is the patient in respiratory failure requiring additional oxygen?
  2. Then look at the pCO2
    • (type 1 vs type 2 respiratory failure)
  3. Then consider acid base balance
    • Acute respiratory acidosis
    • Compensated respiratory acidosis
    • Acute on chronic respiratory acidosis
25
Q

What are the features of acute respiratory acidosis? [3]

A
  1. elevated pCO2,
  2. normal bicarbonate,
  3. acidosis
26
Q

What are the features of compensated respiratory acidosis? [3]

A
  1. elevated pCO2,
  2. elevated bicarbonate (renal compensation),
  3. not acidotic
27
Q

What are the features of acute on chronic respiratory acidosis? [3]

A
  1. elevated pCO2,
  2. elevated bicarbonate,
  3. acidotic
28
Q

What is the alveolar oxygen equation? [1]

A
  1. PAO2 = FiO2 - (1.25 x PaCO2)
    • PAO2 = alveolar oxygen partial pressure, kPa
    • FiO2 = inspired oxygen concentration, kPa
29
Q

Fill in the following table: [12]

A
  1. Increased ↑[H+]
  2. Decreased ↓[HCO3-]
  3. Decreased ↓PCO2
  4. Decreased ↓[H+]
  5. Increased ↑[HCO3-]
  6. Increased ↑PCO2
  7. Increased ↑[H+]
  8. Increased ↑PCO2
  9. Increased ↑[HCO3-]
  10. Decreased ↓[H+]
  11. Decreased ↓PCO2
  12. Decreased ↓[HCO3-]

Week 8 - Respiratory (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions