Week 10 Flashcards
Difference between volume and capacity?
Capacity is the sum of more than one volume
Volume cannot be subdivided
What is the measure of airflow obstruction?
What is it’s normal value?
FEV1.0/FVC ratio
Normal > 0.7
[This is the percentage of the vital capacity which is expired in the first second of maximal expiration.
FEV1.0= Forced expiratory volume 1.0 measures how much air a person can exhale during a forced breath in the first second
FVC= Forced vital capacity is the total amount of air exhaled during the FEV test.]
Difference between obstructive and restrictive lung disease?
Obstructive: Increasing in resting volume due to loss of lung elastic recoil
Restrictive: People with restrictive lung disease cannot fully fill their lungs with air. Their lungs are restricted from fully expanding.
Difference in following patterns between obstructive and restrictive lung disease? FVC FEV1 FEF25-75 MVV FRC RV TLC
Obstructive: FVC - Same/Decrease FEV1 - Decrease FEF25-75 - Decrease MVV- Decrease FRC- Increase RV- Increase TLC- Increase
Restrictive: FVC- Decrease FEV1 - Same/decrease FEF25-75- Same/decrease MVV- Same/decrease FRC- Decrease RV- Decrease TLC- Decrease
Define following measurements: FVC? FEV1 ? FEF 25-75? MVV? FRC? RV? TLC?
FVC: Forced vital capacity is the total amount of air exhaled
FEV1: Forced expiratory volume in the first second
FEF25-75 = Forced Expiratory Flow at 25-75% of FVC
MVV: Maximum Voluntary Ventilation
FRC: Functional Residual Volume, the lung volume at the end of a normal expiration, when the muscles of respiration are completely relaxed
RV: Residual volume, the volume of the lungs after a maximal expiration– the lowest voluntary volume attainable.
TLC: Total lung capacity
In obstructive lung disease:
- Airflow obstruction measure?
- Common diseases?
FEV1.0/FVC < 0.7
Common disease: Asthma, COPD
What is the clinical presentation of asthma?
It is a clinical diagnosis. More than one of the following:
- Wheeze
- Breathlessness
- Chest tightness
- Cough
Especially if diurnal variation in symptoms and history of atopy.
Hyper-responsive to allergens, exercise, cold air
Define asthma
A chronic inflammatory disorder of the airways in susceptible individuals, inflammatory symptoms are usually associated with widespread but variable airflow obstruction and an increase in airway response to a variety of stimuli. Obstruction is often reversible, either spontaneously or with treatment
Effect of airway obstruction on FEV1?
Lower FEV1 as the percentage of vital capacity exhaled is lower due to lower rate
What are the three components of the pathophysiology of asthma?
- Airway narrowing/obstruction
- Airway hyper-responsiveness
- Airway inflammation (eosinophils)
What are the pathological change sin the airways in asthma?
- Cellular infiltration
- Oedematous submucosa
- Thickened BM
- Smooth muscle hypertrophy and hyperplasia
- Mucous plug
- Hyperplasia of mucous glands
- Desquamation of epithelium
- Neovascularisation
What is an example of non-pharmacological treatment of asthma?
SIGN. Shown to:
- Achieve and maintain a normal BM if overweight
- Breathing exercise programmes
- Stop smoking
What is the structure of the pharmacological treatment of asthma?
- Mild intermittent asthma: Inhaled short-acting B2 agonist as required
- Regular preventer therapy: Add dose of corticosteroid per day
- Initial add-on therapy: Add inhaled long acting B2 agonist (LABA) –> Assess control of asthma (good response to LABA).
Benefit from LABA but still poor control = Continue LABA and increase inhaled corticosteroid dose to 800mg/day
No response to LABA = Stop LABA and increase corticosteroid to 800mg/at - Persistent poor control: Consider further increase of corticosteroid or addition of 4th drug (e.g. leukotriene receptor antagonist)
- Continuous or frequent use of oral steroids: Use of daily steroid tablet or refer patient for specialist care
What is COPD?
Preventable and treatable
Characterised by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles/gases
Causes of COPD
- TOBACCO SMOKING
- Indoor/outdoor pollution from biomass fuels
- alpha-1 antitypsin deficiency
Pathophysiology of COPD
- Inflammation and fibrosis of the bronchial wall
- Hypertrophy of the submucosal glands an hypersecretion of mucous
- Loss of elastic, parenchymal lung fibres which hold airway open –> emphysema
Clinical presentation of COPD?
Usually 50s and 60s Chronic cough Sputum production Increased dyspnoea Decreasing exercise tolerance History of exposure to risk factors
Difference between pink puffer and blue bloater presentaiton?
Pink puffer:
- Pink
- Pursed lips as alveoli tend to collapse
- Barrel chest due to air trapping
- Use of accessory muscles
- Decrease breath sounds
Blue bloater:
- Blue = cyanosed
- Bloater = signs of RHF
- Not just a lung disease (Weight loss, CVS disease, depression, osteoporosis)
Describe the different management strategies for different levels of COPD:
- Breathlessness and exercise limitations
- Exacerbations or persistent breathlessness
- Persistent exacerbations or breathlessness
- Breathlessness and exercise limitations
- SABA or SAMA (Short acting muscarinic agonist)
2. Exacerbations or persistent breathlessness [for FEV>50%] -LABA -LAMA (+discontinue SAMA) [for FEV< 50%] -LABA and ICS in a combination inhaler -LAMA (+ discontinue SMA)
- Persistent exacerbations or breathlessness
- LAMA + LABA + ICS in a combo inhaler
ICS= inhaled corticosteroids
What is domiciliary oxygen therapy? Who is it for?
Non-invasive positive pressure ventilation
Patients with PaCo2 <8 kPa
Must have stopped smoking
Must be breated for > 15hrs/day for improve mortaility
Describe the main types of research studies employed in medical research
Observational studies
- Case control
- Cohort
- Cross sectional
Experimental studies
-Randomised and non-randomised trials
Describe the advantages and disadvantages of case study, series or report
Advantages- Quick, cheap, rapid publication, early indicators of problems, can help detects new drug side effects and potential uses
Disadvantages- Statistically weak, no control group, very small numbers of patients, cases may not be generalizable to the wider population
What are the advantages and disadvantages of cross sectional surveys?
Advantages- Cheap, simple, ethically café, useful for planning surposes
Disadvantages- Cause/effect, volunteer bias, unequal distribution of confounders
Usually descriptive studies which may show an association between exposure and outcome
Complications of cross sectional surveys?
Confounders: Uncontrolled extraneous variables
Spurious association: e.g. Is ultrasound harmful to fetus? Varying conclusions