Theme 4: Lecture 7 - Asthma Flashcards
Definition of asthma
- Heterogeneous disease characterised by chronic airways inflammation
- 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.
What causes airflow obstruction
- 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
Atopy
- A form of allergy in which there is a hereditary or constitutional tendency to develop hypersensitivity reactions in response to allergens
- 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
What is asthma in young people usually linked to
Atopy
Symptoms and characteristics 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
Medications that trigger asthma
- Aspirin
- Ibuprofen
- Beta blockers
What do you need to make a diagnosis of 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 are the investigations for asthma that may be done by a GP
- Peak flow monitoring-twice day for 2 weeks
- Spirometry may show airflow obstruction, but may be normal between attacks
What are the investigations for asthma that may be done by the hospital
Skin prick or blood tests may confirm allergies
What are the investigations for asthma that may be done by the GP or hospital
- Chest X-ray often normal, but may show hyperinflation
- Increased eosinophil count in the blood
- Fraction exhaled nitric oxide (FeNO)
Tests of lung function
- Is there airflow obstruction? (FEV1/FVC ratio <70)
- Does it vary over time? (peak expiratory flow rate (PEFR) monitoring-20% diurnal variation worse at night/early morning)
- Is it reversible? (with bronchodilators)
Describe the FeNO (Fraction of exhaled nitric oxide)
- Measure of airways eosinophilic inflammation
- Performed on patients not on any treatment, a positive test (> 40ppb - parts per billion) supports diagnosis of asthma
- Can be done in GP and hospital clinics
- Can be used to monitor treatment/look at compliance
What is the long term non pharmacological management of asthma
- Smoking cessation
- Weight reduction
- Pollution-may provoke acute asthma or aggravate existing asthma but effects from allergens, smoking and infection more significant
ICS
Inhaled corticosteroids
LABA
Long acting beta 2 agonists
Name an inhaled corticosteroid
Beclometasone
Name an inhaled long acting beta 2 agonist (LABA)
Salmeterol
The pharmacological use of inhaled corticosteroids in control of asthma
- Key first line treatment in patients with asthma
- Supresses the inflammation response
- Long term
The pharmacological use of LABAs in control of asthma
- In combination with ICS as add on treatment if still symptomatic
- Never a single agent treatment alone: associated with increased deaths
- Causes relaxation of smooth muscle
- Long term
Theophylline
- Phosphodiesterase inhibitor (Bronchodilator)
- Reversible airways obstruction; severe acute asthma
- Long term
Name a long term oral pharmacological treatment for asthma
Oral theophyllines
How are patients with chronically poorly controlled asthma treated
Low dose long term oral steroids
Name a long dose long term oral steroid treatment for asthma
Prednisolone
SABAs
Short acting beta agonist
Name a SABA
Salbutamol
What are long term treatments for asthma used for
- Control of disease
- Preventers
What are SABAs used for in the treatment of asthma
- Short immediate relief of symptoms
- Relievers
Maintenance and reliever therapy
- 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
- Aim to address and treat the inflammatory aspect of disease by having both ICS and LABA
Broadly, what are the two types of inhalers
- Dry powder inhalers
- Pressurised metered dose inhalers
Dry powder inhalers
- Activated by inspiration by the patient
- Powdered drug is dispersed into particles by the inspiration
Pressurised metered dose inhalers
Drug dissolved in a propellant hydrofluorocarbons (HFCs - negative impact on climate change) under pressure Valve system releases a metered dose
Which type of inhaler has a higher proportion of patients making no mistakes with them
Dry powder inhalers
What should patients use with pressurised metered dose inhalers
A spacer
Things to consider when deciding which inhaler to use
- Where they are in treatment
- Which device they can use (dexterity, inspiratory flow)
- Side effects
- Which device they want to use
- Counter so know how many doses left
- Cost
Very specialised treatments for small numbers of patients with difficult asthma
-Monoclonal antibody:
anti-IgE injections (omalizumab)
anti IL-5 treatment (mepolizumab)
-Bronchial thermoplasty
Bronchial thermoplasty
a medical procedure that some people with severe asthma can have to help open their airways. It’s a heat treatment that reduces the amount of thickened smooth muscle on the inside walls of the airways
Unintentional factors that affect treatment compliance of asthma
- Misunderstanding
- Poor inhaler technique
- Language
- Forgetfulness
- Stress
Intentional factors that affect treatment compliance of asthma
- Concern about side effects
- Denial
- Cost
Describe a personal asthma action plan (PAAP)
- List daily medication to take and explain why
- List which asthma triggers to avoid and importance of smoke free environment
- List what to look for signs of deterioration of asthma/ values for PEFR
- List names and doses of medication to be taken to treat worsening asthma
- List indicators of how and when to seek medical attention
- Easy to understand, 2-3 action points, traffic light colour coded
Benefits of a personal asthma action plan (PAAP)
- Improves asthma control
- Reduces emergency contacts with GP
- Reduces hospital admissions
How dangerous is acute severe asthma
- A medical emergency
- Life threatening
Features of severe acute asthma
- Peak expiratory flow rate (PEFR) 33-50% of best (use % predicted if recent best unknown)
- Can’t complete sentences in one breath
- Respirations ≥25 breaths/min
- Pulse ≥110 beats/min
Life threatening features of asthma
- PEFR <33% of best or predicted
- SpO2 <92% (regardless of air or oxygen)
- Silent chest, cyanosis, or feeble respiratory effort
- Arrhythmia or hypotension
- Exhaustion, altered consciousness
Treatment of severe acute asthma
- Oxygen
- Corticosteroids
- Nebulised bronchodilators – salbutamol + ipratropium bromide
- If poor response, intravenous MgSO4, or intravenous aminophylline
- Exceptionally, intubation and ventilation is required
When can a patient be discharged from hospital following a acute severe asthma attack
- Been on discharge medication for 24 hours
- Inhaler technique checked and recorded
- PEFR >75% of best or predicted and PEFR diurnal variability<25%
Next steps after a patient has been discharged from hospital following an acute severe asthma attack
- 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
