Term
| What does spirometry measure? |
|
Definition
volumes of inspired and expired air
this allows the measurement of 3 of the 4 non-overlapping volumes that make up the total lung capacity |
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Term
| Which volumes are measured in spirometry? |
|
Definition
tidal volume
inspiratory reserve volume
expiratory reserve volume |
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Term
|
Definition
that volume of air moved into or out of the lungs during quiet breathing
500ml |
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Term
| What is inspiratory reserve volume? |
|
Definition
the maximal volume that can be inhaled from the end-inspiratory level.
3000ml |
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Term
| What is expiratory reserve volume? |
|
Definition
the maximal volume of air that can be exhaled from the end-expiratory position.
1000ml |
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Term
| What is inspiratory capacity? |
|
Definition
tidal + inspiratory reserve
how much can you breathe in after a normal expiration
3500ml |
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Term
| What is the vital capacity? |
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Definition
tidal + inspiratory reserve + expiratory reserve
max amount of air you can breathe out after max inspiration
4500ml |
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Term
| What is the residual volume? |
|
Definition
the volume of air remaining in the lungs after a maximal exhalation.
1200ml |
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Term
| What is total lung capacity? |
|
Definition
the volume in the lungs at maximal inflation, the sum of VC and RV.
5700ml |
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Term
| What can spirometry not tell us? |
|
Definition
residual volume
total lung capacity |
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Term
| How can you measure total lung capacity and residual volume? |
|
Definition
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Term
| Describe the helium dilution method |
|
Definition
This technique is a closed-circuit system where a spirometer is filled with a mixture of helium (He) and O2. The amount of He in the spirometer is known at the beginning of the test (Concentration × Volume = Amount). The patient is then asked to breathe (normal breaths) in the mixture starting from FRC (Functional Residual Capacity), which is the gas volume in the lung after a normal breath out. The spirometer measures the He concentration. The He spreads into the lungs of the patient, and settles at a new concentration (C2).
Because there is no leak of substances in the system, the amount of helium remains constant during the test, and the FRC is calculated by using the following equation: |
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Term
| How is total lung capacity and vital capacity calculated? |
|
Definition
TLC = (v1 + V2) - V1
RV = TLC - VC |
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Term
| What is minute ventilation? |
|
Definition
total amount of air flowing into or out of the respiratory system per minute
= Vt x respiration rate |
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Term
| What is typical Vt and respiration rate for a 70kg man? |
|
Definition
0.5L and 12 breaths per min
therefor minute ventilation = 6L min-1 |
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Term
| How much a typical tidal inspiration reaches the alveoli? |
|
Definition
350ml (70%)
due to dead space (150ml) |
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Term
| Give the equation to calculate alveolar ventilation |
|
Definition
(tidal volume - dead space volume) x respiration rate
= 4.2Lmin-1 |
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Term
|
Definition
forced vital capacity (total volume of air expired)
forced expiration volume in 1 second |
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Term
| What does a low FVC indicate? |
|
Definition
| restrictive pulmonary disease |
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Term
| What is a normal FEV1:FVC ratio? |
|
Definition
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Term
| What is value significantly lower than 80% indicative of? |
|
Definition
| increased airway resistance (which is characteristic of obstructive pulmonary disease) |
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Term
| Describe peak expiratory flow measurement |
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Definition
| Following a maximal inspiration, the subject makes a rapid, forceful expiration through the meter, which measures the maximum rate of airflow |
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Term
| What do normal values depend on? |
|
Definition
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Term
| What are values less than 80% of predicted indicative of? |
|
Definition
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Term
| What is peak expiratory flow measurement particularly useful for? |
|
Definition
| assessing the efficacy of rapidly-acting medication (e.g. bronchodilator inhalers for the treatment of asthma) |
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Term
| What are the effects of restrictive diseases? |
|
Definition
In restrictive diseases the expansion of the lung is restricted, resulting in:
- A decreased lung volume
- Increased work of breathing
- Inadequate ventilation |
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Term
| What is the most common cause of restrictive disease? |
|
Definition
| decreased compliance of the lung itself, although decreased compliance of the chest wall, weak muscles or damaged nerves may also be responsible for the restriction |
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Term
| What is the most common symptom of restrictive disease? |
|
Definition
| shortness of breath on exertion; a cough is also common |
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Term
| Examples of restrictive disease |
|
Definition
| asbestosis, sarcoidosis and pulmonary fibrosis |
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Term
|
Definition
Inhalation of microscopic fibres of asbestos may lead, often many years later, to this condition
Once these fibres reach the terminal bronchioles and the alveoli, they trigger the lung’s local immune system and provoke an inflammatory reaction
Macrophages phagocytose the fibres and stimulate fibroblasts to deposit connective tissue
As the fibres cannot be digested, the macrophages die off, releasing cytokines, which attract further macrophages and fibroblastic cells
The result is interstitial fibrosis, causing the alveolar walls to thicken |
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Term
| What are the effects of asbestosis? |
|
Definition
| reduced lung elasticity and interferes with gas diffusion |
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Term
| How is asbestosis treated? |
|
Definition
| no known cure for asbestosis: O2 therapy, physiotherapy, and nebulised drugs to loosen mucus secretions may all provide symptomatic relief |
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Term
| What are obstructive pulmonary disease characterised by? |
|
Definition
airway obstruction and often often associated with inflamed and / or easily collapsible airways resulting in:
- Obstruction to airflow
- Problems exhaling
- Frequent medical clinic visits and hospitalisations |
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Term
| What are the symptoms of obstructive pulmonary disease? |
|
Definition
| Symptoms include cough, shortness of breath, wheezing, feeling very tired or weak whilst exercising |
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Term
| What are examples of obstructive pulmonary disease? |
|
Definition
| asthma and chronic bronchitis |
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Term
| What is asthma characterised by? |
|
Definition
| varying and recurring symptoms, reversible airflow obstruction and bronchospasm |
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Term
|
Definition
| Genetic and environmental factors interact to cause asthma |
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Term
| What are the symptoms of asthma? |
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Definition
| Symptoms can be triggered by a variety of factors, including allergens (pollen, dust mites, etc.), irritants (cigarette smoke, air pollution, etc.), drugs (NSAID’s etc.), viral upper respiratory infections (colds, etc.) and exercise (especially in cold conditions) |
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Term
| What is the goal os asthma treatment? |
|
Definition
| to control the disease: selective β2 agonists such as salbutamol counteract bronchoconstriction; inhaled corticosteroids reduce the inflammatory response |
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