18.1 Asthma and COPD Flashcards
Describe what asthma is.
A chronic inflammatory disease of the airways characterised by variability of symptoms and reversible airway obstruction.
Airways become narrowed due to bronchoconstriction and mucous hypersecretion.
What are the clinical symptoms of asthma?
- Wheeze
- Chest tightness
- Cough
- Mucous production
- Shortness of breath
- Airway hyper-responsiveness = twitchy/sensitive airways e.g. bronchospasm after entering a room filled with smoke
How does airway obstruction reverse in asthma?
Can reverse spontaneously or due to treatment with beta-2-agonists or anti-inflammatory agents (corticosteroids)
What factors influence the variability of asthma?
- Allergens
- Cigarette smoke
- Respiratory infection
- Exercise and hyperventilation
- Weather changes
- Air pollutants
- Food, additives, drugs
- Cold/damp
Describe the epidemiology of asthma.
- Very common, affects at least 300 million people worldwide
- Responsible for 1 in every 250 deaths worldwide
- 15% prevalence in Western world
What are some hypotheses for why asthma is becoming more common?
- Hygiene hypothesis (less bacteria, immune system less busy resulting in autoimmune response)
- Dust mites
- Pollution
- Polyunsaturated fats
What are some risks for developing asthma?
- Genetics
- Maternal smoking
- Viral infections in infancy
- Pre-term birth
Provide a simple overview of the pathophysiology of asthma.
More than 1 inflammatory pathway, more than 1 phenotype.
- Early onset asthma: associated with allergy, inflammation mediated by antigen binding to serum IgE
- Late onset asthma: non-allergy related, mediated by eosinophils and neutrophils
Describe early onset asthma (allergy).
- Antigen binds to IgE
- Degranulation of mast cells
- Histamine release
- Leukotrine release
- Inflammation in airways
Describe the cells involved in the pathophysiology of asthma.
- Neutrophils, mast cells, eosinophils, Th2 cells work together and upregulate inflammatory mediators
- Upregulates mucous secretion
- Sensory nerve activation = bronchoconstriction and hypertrophy of the smooth muscle
- Plasma leakage and oedema, also contributes to bronchoconstriction
- Over time, epithelial shedding occurs, can cause epithelial fibrosis if asthma is left untreated- permanent airway damage
Summarise the causes of smooth muscle dysfunction and airway inflammation in asthma.
How can airway obstruction be measured?
- Peak flow meter
- Spirometry
How is asthma diagnosed?
There isn’t one test that accurately diagnoses asthma.
Thorough history is required.
Investigations are used to help to confirm a diagnosis.
What is the typical presentation of a patient with asthma?
- History of intermittent and variable wheeze, cough, breathlessness
- Tend to get worse with exertion and specific triggers
- Symptoms tend to be worse at night as cortisol drops (anti-inflammatory and bronchodilator)
- Improves with salbutamol short term, steroids long term
- May have a history of atopy (rhinitis, eczema etc), family history
- Ask about occupation e.g. baker, paint sprayer, construction
What investigations are carried out to support an asthma diagnosis?
- Ask patient to keep diary and record peak flow measurements
- Spirometry before and after salbutamol (beta 2 agonist), if FEV1 improves by 200ml and 15% they likely have asthma
- Exercise testing with pre and post spirometry
- Skin prick tests
- Blood tests (IgE levels/RAST)
What are FEV1 and FVC?
FEV1 = forced expiratory volume in 1 second
FVC = forced vital capacity (the amount of air that can be forcibly exhaled from your lungs after taking the deepest breath possible)
FEV1 and FVC ratio is important, measured using spirometry.
What are the aims of asthma management?
- No daytime symptoms
- No night-time awakening due to asthma
- No need for rescue medication
- No exacerbations
- No limitations on daily activity including exercise
- Normal lung function
- Minimal side effects from medication
What are the consequences of poor asthma control?
- Exacerbations
- Development of chronic, irreversible asthma
- Epithelial fibrosis
What closed questions should be asked by a dentist to an asthma patient?
- Have you had any daytime asthma symptoms recently?
- Have you needed to use your blue inhaler recently?
- Do you wake up in the middle of the night due to your asthma?
- Have you had an attack or needed emergency medical attention recently?
What inhaled medication is used to manage asthma?
- Inhaled steroids are used as a long term preventer (e.g. beclamethasone- brown inhaler)
- Beta-2-agonist for immediate relief (e.g. salbutamol- blue inhaler)
- Pts begin with a low dose corticosteroid inhaler and the dose is increased if symptoms persist
What non-inhaler treatment is used to manage asthma?
- Antihistamines
- Steroid tablets
- Aminophylline (bronchodilator)
- Montelukast
- Nebuliser
- Omalizumab injection (biological theropy which ‘mops up’ IgE)
What may cause difficult asthma/poorly controlled asthma?
- Lack of compliance with inhalers
- Poor inhaler technique
- Incorrect diagnosis
- Peristent exposure to allergen or trigger?
- Concomitant allergic rhinitis
- Other drugs making asthma control worse e.g. beta blockers, NSAIDs
- Smoking, pollution, stress, occupation
What is an asthma exacerbation?
- Sustained worsening of symptoms, usually accompanied by a fall in peak flow
- Either due to poor control or viral illness
- Can often lead to hospital admission
What is chronic obstructive pulmonary disease?
A treatable and preventable condition, characterised by airflow obstruction, which is usually progressive- not fully reversible and does not change markedly over several months (unlike asthma which is a variable condition).
- Airflow obstruction is associated with an abnormal inflammatory response in the lungs in response to noxious stimuli
- Primarily affects the lungs but also produces systemic consequences
