Asthma Flashcards
Three typical features of asthma
Airflow limitation that is usually reversible spontaneously or with treatment
Airway hyper-responsiveness (AHR)
Bronchial inflammation with T lymphocytes, mast cells, eosinophils.
Pathophysiology in asthma.
T lymphocytes, eosinophils and mast cells
Plasma exudation
Oedema
Smooth muscle hypertrophy
Matrix deposition
Mucus plugging
Epithelial damage
What is the most common association to childhood-asthma?
Often accompanied by asthma and reacts to allergens.
They have a wheezing illness with inhaled allergic triggers.
Is middle aged onset of asthma usually allergic?
No, it can be, but it often starts by getting triggered due to respiratory infection.
Give causes of developing asthma in non-atopic individuals in middle age.
Infection
Occupational agents such as toluene diisocyanate
Intolerance to NSAIDs such as aspirin and ibuprofen
B-blockers
How are IgE levels related to asthma?
In atopic asthma elevated serum IgE levels are linked to airway hyper-responsiveness.
However elevated IgE levels cannot confirm diagnosis of asthma.
Non-elevated levels of IgE does not exclude asthma.
Genetic factors of asthma.
No single gene for asthma but several, in combination with environmental factors might influence its development.
Environmental factors of asthma.
Early childhood exposure to allergens and maternal smoking has a major influence on IgE production.
Hygiene hypothesis
Dirtier environment might be protective
Aspergillus fumigatus
Give examples of precipitating factors of asthma.
Occupational sensitisers
Cold air and exercise
Atmospheric pollution and irritant dusts
Vapours and fumes
Diet
Emotion
Drugs
Occupational sensitisers are divided into two groups.
Which?
Low-molecular-weight (Non-IgE)
High-molecular weight (IgE)
Give examples of LMW non IgE occupational sensitisers.
Isocyanates
Colophony fumes
Wood dust
Drugs
Bleaches and dyes
Complex metal salts like nickel, platinum and chromium.
Which occupations might be exposedto isocyanates?
Polyurethane varnishes
Industrial coatings
Spray painting
What occupations might be exposed to colophony fumes?
Soldering/welders
Electronics industry
Give examples of HMW (IgE) occupational sensitisers.
Allergens from animals and insects
Antibiotics
Latex
Proteolytic enzymes
Complex salts of platinum
Acid anhydrides and polyamine hardening agents
What can decrease the risk of developing some forms of occupational asthma?
Not smoking/stop smoking
Explain the difference in developing asthma due to exposure to occupational sensitisers in atopic vs non-atopic asthma.
Atopic asthma has a more rapid onset due to the development of IgE antibody.
Non-atopic can develop asthma but does so more slowly, and need longer exposure.
Explain the effects of weather and exercise on asthma.
Prolonged exercise can induce an asthma attack, this is commonly after the exercise itself.
Also inhalation of cold and dry air can set off an attack.
What is exercise-induced asthma driven by?
Release of histamine, prostaglandins and leukotrienes from mast cells, as well as stimulation of neural reflexes.
Explain triggers of asthma found out in the open air.
Tobacco smoke
Car exhaust fumes
Solvents
Strong perfumes
High concentrations of airborne dust
Give examples of food which have shown to be protective against asthma.
Fresh fruit and vegetables.
Possible due to greater consumption of anti-oxidants.
Genetic variation in antioxidant enzymes is associated with more severe asthma.
Give examples of drugs that can trigger an asthma attack.
NSAIDs such as aspirin, indometacin and ibuprofen.
Beta-blockers
In what patients are NSAID intolerance especially prevalent in?
Patients with both asthma and nasal polyps
Why might beta-blockers trigger an asthma attack?
Airways have direct parasymp innervation elliciting bronchoconstriction.
There is no direct sympathetic innervation of bronchial smooth muscle.
This means that when bronchoconstriction happens due to parasymp, bronchodilation is critically dependent on circulating adrenaline.
Inhibition of b1 can therefore be very serious.
Clinical features of asthma.
Wheezingattacks and episodic dyspnoea.
The symptoms are usually worst during night, especially when uncontrolled.
Bilateral widespread polyphonic wheeze
Shows a diurnal variation.
Cough is common, cough is more common at night.
Triggers to asthma attack or worsening asthma are usually appearing.
Investigations of asthma
Lung function test
Histamine or methacholine bronchial provocation/challenge test
Trial of corticosteroids
Exhaled nitric oxide
Blood and sputum tests
CXR
Skin tests
Allergen provocation tests
What lung function tests might be done in asthma?
PEFR
Spirometry
Explain PEFR testing in asthma.
PEFR measurements on waking, prior to taking a bronchodilator, before bed, and after taking a bronchodilator.
This shows the variable airflow limitation.
Diurnal variation in PEFR is a good measure of asthma activity.
Explain spirometry in asthma.
Especially good for assessing variability.
An improvement in FEV1 or PEFR following inhalation of a bronchodilator can diagnose asthma.
How much of an improvement in FEV1 or PEFR is needed to support a diagnosis of asthma?
Improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
Explain a trial of corticosteroids as an investigation in asthma.
Prednisolone 30 mg orally should be given daily for 2 weeks.
Lung functions are measured before and after the course.
An improvement of 15% in FEV1 confirms the presence of reversible element.
It indicates that the administration of inhaled steroids will prove beneficial for the patient.
Explain exhaled nitric oxide in asthma.
A measure of airway inflammation.
Can also be used to assess corticosteroid response.
CXR findings on investigating asthma.
No diagnostic features.
Overinflation is characteristic during an acute episode or in chronic severe disease.
CXR is more helpful in excluding pneumothorax, and allergic bronchopulmonary aspergillosis.
Explain skin-prick tests in asthma.
Should be performed to help identify allergic trigger factors.
It is not diagnostic on its own.
When might allergen provocation test be done in asthma?
To investigate patients with suspected occupational asthma.
Not ordinary.
Explain how to diagnose asthma in adults.
It is a mix of clinical features, past medical history and family history.
Also triggers should be evaluated and classical diurnal variation.
A lung function test (spirometry) and PEFR.
PEFR can be done in a calender for the patient to record it during the day.
Trial of corticosteroids or beta-agonists is usually done to see improvement.
eNO can support diagnosis.
If all else fails bronchial challenge test is definitive.
Explain how to diagnose severe asthma.
Based on signs such as using your reliever inhaler more than three times a week.
Need for tablet steroid therapy three days or longer, two or more times per year.
Needing steroid tablets every day.
Symptoms when an attack occurs.
How many A&E visits
If it severely affects your life.
Then usual tests are carried out as well.
What are the aims of treatment in asthma?
Abolish symptoms
Restore normal or best possible lung function
Reduce risk of severe attacks
Enable normal growth to occur in children
Minimise absence from school or employment
How are the aims of asthma treatment achieved?
Education for both family and patient
Participation of both patient and family in treatment
Avoidance of triggers
Use of the lowest effective doses possibly needed.
How can extrinsic factors be controlled?
In children sublingual allergen immunotherapy can be done to reduce sensitivity to house dustmites
Active and passive smoking should be avoided.
Avoid beta-blockers in tablets or eye-drops.
Avoid NSAIDs, COX-2i might be better tolerated.
How to diagnose asthma in children under 5.
Treat symptoms based on clinical judgement and observations.
If they still have symptoms when they reach 5 yo, they should be able to carry out objective tests.
If they still are not able to do so continue as before and review in 6 to 12 months and try the tests again.
When should a FeNO test be offered in adults?
When there is normal spirometry or non-reversible spirometry with bronchodilators.
What is a positive FeNO test in children and adults?
Children = 35 ppb or more
Adults = 40 ppb or more
When should a bronchial test challenge be done?
Normal spirometry and…
FeNO level of 40 ppb or more and no variability in peak flow readings or
FeNO level of 39 ppb or less with variability in peak flow readings.
What is a positive bronchodilator reversibility test in adults?
Improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
What is a positive BDR result in children?
Improvement in FEV1 of 12% or more.
What is a positive peak flow variability in adults and children?
20% or more
What is a positive bronchial challenge test in adults?
Provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) of 8 mg/ml or less
What is a positive bronchial challenge test in children?
It is not performed in children.
Explain the diagnostic algorithm of asthma.
Algorithm for objective tests in children 5-16.
Algorithm for objective tests in patients 17 or older.
Give examples of why asthma might not be controlled.
Alternative diagnoses
Lack of adherence
Suboptimal inhaler technique
Smoking
Occupational exposures
Environmental exposures
Psychosocial factors
Explain the pharmacological treatment pathway in newly diagnosed asthma in adults (17 and older)
If there is an infrequent short-lived wheeze and normal lung function offer a SABA alone. Bold means symptom relief.
If asthma is uncontrolled for 4 to 8 weeks or if initial symptoms indicate maintenance therapy right away…
Offer low dose of ICS with a SABA.
If asthma is uncontrolled for 4 to 8 weeks…
Low dose ICS, LTRA and a SABA.
If asthma is uncontrolled for 4 to 8 weeks…
Low dose ICS, LABA, SABA +/- LTRA.
If asthma is uncontrolled for 4 to 8 weeks…
Low dose ICS, LABA within MART regimen +/- LTRA and Low dose ICS, LABA within MART regimen.
If asthma is uncontrolled for 4 to 8 weeks…
Moderate ICS dose, LABA either within MART regimen or as a fixed dose +/- LTRA and Low dose ICS, LABA within MART regimen or consider changing to SABA.
If asthma is uncontrolled for 4 to 8 weeks…
High dose ICS, LABA as fixed dose, +/- LTRA + SABA
or
Continuing moderate ICS dose with another treatment such as LAMA or theophylline + SABA or low dose ICS with LABA within MART regimen.
or
Refer to specialist
Explain the pharmacological treatment pathway in newly diagnosed patients 5-16 yo.
Infrequent and short lived wheeze and normal lung function used SABA alone.
If asthma is uncontrolled for 4 to 8 weeks or if the initial symptoms suggest maintenance treatment…
Paediatric low dose of ICS and SABA
If asthma is uncontrolled for 4 to 8 weeks…
Paediatric low dose of ICS, LTRA and SABA
If asthma is uncontrolled for 4 to 8 weeks…
Paediatric low dose of ICS, LABA and stop LTRA. Also give SABA.
If asthma is uncontrolled for 4 to 8 weeks…
Paediatric low dose of ICS, LABA within a MART regimen, paediatric low dose of ICS, LABA within a MART regimen.
If asthma is uncontrolled for 4 to 8 weeks…
Paediatric moderate dose of ICS, LABA within a MART regimen or as a fixed dose, paediatric low dose of ICS, LABA within a MART regimen or change to SABA.
If asthma is uncontrolled for 4 to 8 weeks…
Refer to specialist
or
Paediatric high dose of ICS and LABA as a fixed dose + SABA
or
Paediatric moderate dose of ICS and trial of treatment of e.g. theophylline + SABA or low dose ICS with a LABA within a MART regimen.
Explain the pharmacological treatment pathway in suspected asthma in children under 5.
Symptoms that do not indicate immediate maintenance therapy use SABA alone.
If asthma is uncontrolled for 4 to 8 weeks or if symptoms indicate need for immediate maintenance therapy…
8 week trial dose of paediatric low dose of ICS + SABA
If symptoms did not resolve consider alternative diagnoses.
If symptoms did resolve, but reverted after more than 4 weeks after the trial ended then repeat the 8 week trial.
If symptoms did resolve but reverted before 4 weeks after the trial ended…
Paediatric low dose of ICS and SABA
If asthma is uncontrolled for 4 to 8 weeks…
Paediatric low dose of ICS and LTRA + SABA
If asthma is uncontrolled for 4 to 8 weeks…
Stop LTRA but continue with paediatric low dose of ICS + SABA and refer to specialist.
Give examples of SABAs
Salbutamol
Terbutaline
Should only be used as a reliever
How are SABAs prescribed?
Two puffs as required
Give examples of LABAs.
Salmeterol
Formoterol
Given once or twice daily
Give exampels of inhaled corticosteroids.
Beclometasone (most common)
Budesonide
Fluticasone propionate
Fluticasone furoate
Mometasone furoate
Triamcinolone
Side effects of inhaled ICS.
Oral thrush (rinse mouth after use)
Hoarseness of voice
Subcapsular cataract formation
Osteoporosis.
What can be given as steroid sparing agents in steroid-dependent asthmatics?
Methotrexate
Ciclosporin
Nowadays biologic monoclonal antibodies are now preferred.
Give an example of a SAMA.
Ipratropium used in acute severe exacerbations of asthma.
Give examples of LAMAs.
Tiotropium
Aclidinium
Give examples of other anti-inflammatory drugs in asthma.
Sodium cromoglicate
Nedocromil sodium.
How does sodium cromoglicate and nedocromil sodium work?
Prevents activation of mast cells, eosinophils and epithelial cells.
However not lymphocytes.
This is through blocking a specific chloride channel preventing calcium influx.
These drugs are not routinely used
Give examples of monoclonal antibodies that can be used in asthma.
Omalizumab
Mepolizumab
Reslizumab
Benralizumab
Explain use and action of omalizumab.
Chelates free IgE and downregulates the number and activity of mast cells and basophils.
It is given subcut every 2-4 weeks depending on total serum IgE levels and body weight.
Can be cost-effective in patients with frequent exacerbations requiring oral corticosteroids.
Explain the use and action of mepolizumab, reslizumab and benralizumab..
Acts against IL-5 or its receptor.
Can be effective in eosinophilic asthma.
What is a novel non-pharmacological management of asthma?
Bronchial thermoplasty.
Explain how bronchial thermoplasty works.
Novel approach in moderate to severe persistent asthma.
Uses radiofrequency radiation to heat the bronchial wall and reduce the mass of airway smooth muscle, decreasing bronchoconstriction.
What are asthma exacerbations most commonly caused by?
Lack of adherence
Respiratory virus infections
Exposure to an allergen or triggering drug.
Features of moderate acute asthma.
Increasing symptoms;
Peak flow > 50-75% best or predicted;
No features of acute severe asthma.
Features of acute severe asthma.
Any one of the following:
Peak flow 33-50% best or predicted;
Respiratory rate ≥ 25/min;
Heart rate ≥ 110/min;
Inability to complete sentences in one breath.
Features of life-threatening asthma attack.
Peak flow < 33% best or predicted;
Arterial oxygen saturation (SpO2) < 92%;
Partial arterial pressure of oxygen (PaO2) < 8 kPa;
Normal partial arterial pressure of carbon dioxide (PaCO2) (4.6–6.0 kPa);
Silent chest;
Cyanosis;
Poor respiratory effort;
Arrhythmia;
Exhaustion;
Altered conscious level;
Hypotension.
Features of near-fatal acute asthma.
Raised PaCO2 and/or the need for mechanical ventilation with raised inflation pressures.
PaO2 <8kPa despite treatment with O2
Low and/or falling arterial pH
Treatment pathway of acute severe asthma.
Supplementary O2 to stay between 94-98% SpO2.
Salbutamol 5mg (or terbutaline 10mg) nebulised with O2
IV hydrocortisone 100mg or oral Prednisolone 40-50mg.
Nebulised Ipratropium bromide can be given in acute severe or life-threatening along with SABA, or if SABA does not give enough of a bronchodilation. 0.5 mg/6h nebulised
IV magnesium sulfate can be given .
In worst case scenarios IV aminophylline can also be given.
Ventilation is required for patients deteriorating past this regime.
CXR can be helpful to rule of pneumothorax.
What organism is acute bronchitis in previously healthy subjects?
Usually viral.
What organisms are common in sequel to a viral infection in smokers and COPD?
S. pneumoniae
H. influenzae
Clinical features of acute bronchitis.
Irritating, non-productive cough, together with discomfort behind the sternum.
Chest tightness
Dyspnoea
Wheezing.
Cough can become productive later on.
Treatment of acute bronchitis.
Otherwise healthy adults the disease improves spontaneously usually in 4-8 days without serious illness.
Antibiotics are however often given, although their purpose is not always clear.
Acute asthma management (according to workbook)
ABCDE
SpO2 of 94-98%
ABG if sats are <92%
5 mg nebulised Salbutamol
40mg oral Prednisolone STAT (IV hydrocortisone if PO not possible)
Management of severe acute asthma treatment (according to workbook)
Nebulised ipratropium bromide 500 micrograms
Consider back to back salbutamol
Management of life-threatening or near fatal asthma (according to workbook).
Urgent ITU or anaesthesist assessment
Urgent portable CXR
IV aminophylline
Consider IV salbutamol if nebulised route is ineffective.
Criteria for safe asthma discharge after exacerbation.
PEFR >75% within an hour of treatment can be dischared if there are no other reasons to admit.
Stop regular nebulisers for 24 hours prior to discharge
Inpatient asthma nurse review to reassess inhaler technique and adherence
Provide PEFR meter and written asthma action plan
5 days oral prednisolone
GP follow up within 2 working days
Resp clinic follow up within 4 weeks
For severe or worse, also consider psychosocial factors.
Criteria for discharge of an asthma patient.
Been stable on discharge medication for 24h
Had inhaler technique checked
PEFR >75 predicted or best with diurnal variability <25%
Steroid inhaled and oral + bronchodilator therapy up to date
Their own PEF meter and written management plan
GP appointment within 2d
Resp clinic appointment within 4wks.
What is the MART regime?
A combination inhaler containing a low dose inhaled corticosteroid and a fast acting LABA.
This replaces all other inhalers and the patient uses this single inhaler both regularly as a “preventer” and also as a “reliever” when they have symptoms.
