Lecture 7: Asthma Flashcards
What is the WHO definition of asthma?
Is a disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. In an individual, they may occur from hour to hour and day to day
When does asthma most commonly present?
In childhood or in middle age
What % of children with mild asthma will be symptom free by 21yo?
50%
What % of people with more persistent asthma will continue to have symptoms into adulthood?
70%
What causes airflow obstruction in asthma?
Bronchoconstriction - contraction of the smooth muscle in the bronchial wall
Bronchial secretions and plugs of mucus - due to inflammation of the bronchial wall
Oedema of the bronchial wall - due to inflammation the lining mucosa of the bronchial wall
What is atopy?
Asthma in young people usually linked to atopy
Tendency to form IgE antibodies to allergens (such as pollen, house dust mites or animals)
Often associated hay fever or eczema in the personal or family history
Which interleukins are associated with B cell and plasma cell activation?
IL-4 and IL-13
What receptor is expressed by bast cells and basophils that are activated in asthma?
FCeRI
What interleukin is associated with activation of eosinophils?
IL-5
What is released in response to mast cell, basophil and eosinophil activation in asthma?
Histamine
Leukotrienes
Prostaglandins
Cytokines
What are the symptoms of asthma?
Cough
Wheeze
Breathlessness
Chest tightness
Occurs in episodes with periods of no (or minimal symptoms)
Diurnal variability-so worse at night or early morning
What mechanisms can act as triggers in asthma?
Aspirin
Ibuprofen
Beta blockers
What must be taken into account when diagnosing asthma?
History is crucial-need more than one symptom
Symptom free periods
Past medical history (previous wheezing illness, hay fever, eczema), family history (of any atopic disease), and social history (occupation, pets) can provide clues
Alternative diagnosis unlikely-what could these be?
Physical examination may be normal except during an attack
What investigations can be carried out to assess asthma?
GP:
- peak flow monitoring-twice day for 2 weeks
- spirometry may show airflow obstruction, but may be normal between attacks
GP/Hospital:
- chest X-ray often normal, but may show hyperinflation
- increased eosinophil count in the blood
- fraction exhaled nitric oxide (FeNO)
Hospital:
- skin prick or blood tests may confirm allergies
How do you know if theres airflow obstruction?
FEV1/FVC ratio <70
What peak flow would be expected in asthma?
20% diurnal variation
Worse at night/early morning
Is the affect on lung function reversible?
With bronchodilators (so after treatment with salbutamol) 15% and 200mls improvement in FEV1 from baseline
What is FeNO?
Fraction of exhaled nitric oxide
Measure of airways eosinophilic inflammation
Performed on patients not on any treatment
A positive test (> 40ppb) supports diagnosis of asthma
Can be used to monitor treatment/look at compliance
What are the non-pharmacological management options for asthma?
Smoking cessation
Weight reduction
Pollution-may provoke acute asthma or aggravate existing asthma but effects from allergens, smoking and infection more significant
What are the pharmacological management options for asthma?
“Preventers”
- Inhaled corticosteroids (ICS)
- Inhaled Long acting beta 2 agonists (LABA)
- Leukotriene or theophylline when poorly controlled
“Relievers”
- Short acting beta agonists (SABA)
What is the first line treatment in patients with asthma?
Inhaled corticosteroids (ICS)
Beclometasone, fluticasone, budesonide, ciclesonide
When should LABAs be used in asthma?
Formoterol Salmeterol
In combination with ICS as add on treatment if still symptomatic
Never a single agent treatment alone: associated with increased deaths
What SABA are used?
Salbutamol/Terbutaline - As inhaler (100mcg) or nebuliser (high dose 2.5mg, driven by oxygen)
What is MART?
LABA formoterol has short onset of action - equivalent of salbutamol (SABA)
So certain specific ICS/LABA combinations can be used as relievers as well as preventers
So patients can take additional doses (4/day) for short period (2-3 days) to rapidly treat any worsening asthma symptoms
What are dry powder inhalers?
Activated by inspiration by the patient
Powdered drug is dispersed into particles by the inspiration
What are pressurised metered dose inhalers?
Drug dissolved in a propellant hydrofluorocarbons (HFCs) under pressure valve system releases a metered dose
What are the proportions of patients making no mistakes with their inhalers (DPI, pMDI and pMDI+spacer)?
DPI - 53-59%
pMDI - 23-43%
pMDI+spacer - 55-57%
What should be considered before deciding which inhaler to prescribe?
Where are they in treatment
What device can they use
Dexterity
Inspiratory flow
Side effects: oral candidiasis/thrush (ICS), tremor + tachycardia (SABA/LABA)
What device do they want to use (HFCs)
Carbon footprint
Cost
What are the three key questions in asthma?
Have you had difficulty sleeping because of your asthma symptoms (including cough)?
Have you had your usual asthma symptoms during the day (cough, wheeze, chest tightness or breathlessness)?
Has your asthma interfered with your usual activities (eg housework, work, school)?
What are the specialised treatments available in asthma?
Monoclonal antibody
- anti-IgE injections (omalizumab)
- anti IL-5 treatment (mepolizumab)
What are the reasons for low compliance with inhalers?
Unintentional
- Misunderstanding
- Poor inhaler technique
- Language
- Forgetfulness, stress
Intentional
- Concern about side-effects
- Denial
What are the benefits to a PAAP?
Improves asthma control
Reduces emergency contacts with GP
Reduces hospital admissions
What are the features of acute sever asthma?
Peak expiratory flow rate (PEFR)- 33-50% of best
Can’t complete sentences in one breath
Respirations ≥25 breaths/min
Pulse ≥110 beats/min
What are the features of life threatening asthma?
PEFR <33% of best or predicted
SpO2 <92%
Silent chest, cyanosis, or feeble respiratory effort
Arrhythmia or hypotension
Exhaustion, altered consciousness
When can someone be discharged from hospital?
Been on discharge medication for 24 hours
Inhaler technique checked and recorded
PEFR >75% of best or predicted and PEFR diurnal variability<25%
Treatment with oral and inhaled steroids in addition to bronchodilators
Own PEFR meter and written PAAP
GP/Nurse follow up arranged within 2 working days
Follow up appointment in respiratory clinic within 4 weeks
