Asthma Flashcards
Explain asthma to a patient
- Normal anatomy/physiology
- What the disease is
- Cause
- Complications/problems
- Management
As we breath, air has to flow down our wind pipe, through the bronchioles (tube connected to each lung) and then the lungs fill with air before we breath out to push air back through the bronchioles.
Asthma is a common lifelong condition that affects breathing. Asthma causes the bronchioles/airway to become more reactive towards certain stimuli, and if exposed to the stimuli can cause inflammation of the airway, which narrows the air flow in and out of the lungs.
There is no known cause of asthma and therefore it is not reversible or curable. However, asthma is a common condition that, if managed correctly, can cause few problems.
Some of the things you might experience with asthma include a wheeze, a cough, shortness of breath and chest tightness. These symptoms won’t be present all the time but they are brought on by certain triggers
Triggers include cold weather, smoke, exercise, anxiety/stress, chest infections or allergies (dust, pets, food, pollen etc.)
Asthma can be controlled with various medications including inhalers and steroids if needed.
Pathophysiology of asthma (IOH)
Airway inflammation
Airway oedema and increased mucus secretion worsens obstruction and bronchial reactivity
T lymphocytes release cytokines
Airflow obstruction
Caused by acute bronchoconstriction, airways oedema, chronic mucus plug formation and airway re-modelling
Acute bronchoconstriction = IgE dependent mediator released upon exposure to allergens.
Airways oedema = Occurs 6-24 hours after allergen exposure
Chronic mucus plug= Exudate of serum protein + cell debris (weeks to resolve)
Airways re-modelling = Structural changes due to long standing inflammation (reduces the reversibility)
Bronchial hyper-responsiveness
Hyperinflation compensates for airway obstruction, but is limited and therefore alveolar hyperventilation occurs.
Uneven changes in airflow resistance, uneven air distribution, alteration in circulation, and vasoconstriction all cause a ventilation - perfusion mismatch (V-P mismatch)
Triggers for asthma
Cold weather Allergens (dust, pets, food, pollen) Exercise Smoking Anxiety/stress Chest infections
Signs and symptoms of asthma
Wheeze Cough Dyspnoea Chest tightness History of recurrent bronchitis, bronchiolitis History of recurrent cough with cold History of recurrent chest infections
Diagnosis of asthma
Clinical History
- wheeze, cough, breathlessness
- seasonal variations
- Triggers for worsening symptoms
- Personal/family history of atopic disorders
Examination
- Expiratory wheeze
Fractional exhaled Nitric oxide tests (FeNO)
- Offered to patients aged 17+
- FeNO levle >40 = positive test
Spirometry
- Offered to patients aged 5+
- FEV1/FVC ratio <70% = positive for obstructive airway disease
What does the FeNO test show and how?
Fractional exhaled Nitric oxide tests (FeNO)
- Offered to patients aged 17+
- FeNO level >40 = positive test
- Inflammation in the airways produces nitric oxide, and the FeNO test assesses how much NO is expelled on expiration. This therefore tells the doctors if there is inflammation in the airway and whether or not steroids may be needed.
What does the Spirometry /volume-flow loop show for asthmatic patients?
Spirometry
- Offered to patients aged 5+
- Forced vital capacity (FVC) – the maximum amount of air the patient can exhale in 6 seconds
- Forced expiratory volume in 1 second (FEV1) – the maximum amount of air the patient can exhale in 1 second
In obstructive disease:
FVC is Normal (very mild obstruction)/ decreased (severe obstruction)
FEV1 is Normal (very mild obstruction)/ decreased (mod-severe obstruction)
FEV1: FVC ratio is Decreased <70%
FEV1/FVC ratio <70% = positive for obstructive airway disease
How is asthma managed?
- SABA
- SABA + ICS
- SABA, ICS + LABA
- SABA, ICS, LABA + LTRA/LAMA
- SABA, ICS, LABA, LTRA/LAMA + Theophylline
SABA = Salbutamol ICS = Beclamethasone LABA = Salmeterol LTRA = Montelukast LAMA = Tiotropium
How do you stage exacerbation’s of Asthma?
Moderate exacerbation
- PEFR <50-75% best
- Normal speech
- No features of acute severe/life threatening asthma
Acute severe exacerbation
- PEFR = 33-50% best
- Resp. rate = >25/min
- Heart rate = >110/min
- Inability to complete sentences
- Oxygen saturation’s of 92%
Life threatening
- PEFR = <33% best
- Oxygen saturation’s <92%
- Altered consciousness and confusion
- Cardiac arrhythhmia
- Exhaustion
- Cyanosis
- Hypotension
How do you treat an exacerbation of asthma?
- Oxygen (15L)
- Nebulised SABA
- Nebulised LABA
- Oral prednisolone / IV hydrocortisone
- IV magnesium sulphate
