Chronic Asthma Flashcards
What is asthma?
It is a chronic inflammatory airway disease
leading to variable airway obstruction
What hypersensitivity reaction is associated with asthma?
Type 1
What is the pathophyiosology of asthma?
In asthma patients, the smooth muscle within the airways is hypersensitive, responding to stimuli by constricting and therefore causing airflow obstruction
What is the key characteristic feature of the bronchoconstrcition associated with asthma?
It is reversible
What are the nine risk factors of asthma?
Atopy Personal/Family History
Antenatal Factors
Low Birth Weight
Bottle Feeding
Obesity
Allergen Exposure
Air Pollution
Hygiene Hypothesis
Occupation
What is atopy?
It is defined as the body’s predisposition to develop an antibody called immunoglobulin E in response to environmental allergens
What is more influential - maternal or paternal atopy?
Maternal
What are the three main atopic conditions?
Asthma
Atopic dermatitis (eczema)
Allergic rhinitis (hayfever)
What two genes are associated with asthma?
ADAM33
ORMDL3
What two antenatal risk factors are associated with asthma?
Maternal Smoking
Viral Infection
What antenatal viral infection is most commonly associated with asthma?
RSV
What is the hygiene hypothesis?
It refers to reduced exposure to infectious agents in childhood resulting in abnormal development of the immune system - specifically resulting in a Th2 predominant response
What is the most common occupational risk factor of asthma?
Isocyanate exposure
What are the three clinical features of asthma?
Dry Cough
Dyspnoea
Bilateral Expiratory Wheeze
What are the two characteristics of the clinical features associated with asthma?
Episodic
Diurnal variability - worse in the early morning and night
What clincal feature indiciates a differential diagnosis to asthma?
Peripheral paraesthesia during dyspnoea episodes
List seven common triggers of asthma
Infection
Dust
Exercise
Animals
Smoking
Cold air
Food allergens
What three food allergens commonly trigger asthma?
Peanuts
Shellfish
Eggs
In most cases how is asthma diagnosed?
Clinically
What four investigations can be used to confirm a diagnosis of asthma?
Spirometry
Peak Flow Meter
Fractional Exhaled Nitric Oxide (FeNO)
Direct Bronchial Challenge Test
What two things need to be proven through investigations, in order to confirm a diagnosis of asthma?
Airflow obstruction
Airflow obstruction reversibility
What are the two first line investigations used to diagnose asthma?
Spirometry
FeNO
What is spirometry?
It is an investigation that measures the volume and flow of air during exhalation and inhalation
What three metrics are obtained from spirometry?
Forced Expiratory Volume 1 (FEV1)
Forced Vital Capacity (FVC)
FEV1 : FVC
What is FEV1?
It is defined as the volume that has been exhaled at the end of the first second of forced expiration
What is FVC?
It is defined as the volume that has been exhaled after a maximal expiration, following a full inspiration
What four spirometry results indicate a diagnosis of asthma?
Reduced FEV1
Normal FVC
FEV1 : FVC < 70%
Increased TCLO
Following abnormal spirometry results, what should be tested?
We test the reversibility of airflow obstruction
In what two ways can we test reversibility of airflow obstruction with spirometry?
Bronchodilator response
Corticosteroid response
Describe how bronchodilators can be used to test the reversibility of airflow obstruction in spirometry
We administer 400ug inhaled salbutamol or 2.5-5mg nebulised salbutamol
We conduct spirometry tests 15 minutes following administration
The results are deemed to demonstrate reversibility when FEV1 > 400ml or FEV1 of > 12%
Describe how corticosteroids can be used to test the reversibility of airflow obstruction in spirometry
We administer 30mg oral prednisolone for a period of 14 days or 500mcg inhaled beclomethasone for a period of 6 weeks
The results are deemed to demonstrate reversibility when FEV1 > 400ml or FEV1 of > 12%
In cases where spirometry results are normal, however clinical suspicion remains high what is the most appropriate next step? Why?
FeNO
This is due to the fact that normal spirometry doesn’t exclude asthma as a diagnosis
What are peak flow meter tests?
They involve the patients blowing as hard and as fast as they can into a small handheld device
This measures the rate at which air is exhaled from the lungs, obtaining a peak expiratory flow (PEF) score in litres of air breathed out per minute
How can peak flow meter tests be used to diagnose asthma?
We ask patients to conduct peak flow meter readings at home twice daily for a period of 2 – 4 weeks
These readings are then plotted upon a chart, which incorporate the patient’s age, height and sex
What three peak flow meter test results indicate asthma?
Morning/nocturnal dips
A gradual decline of results over
A variability of results greater than 20% on more than 3 consecutive days of the week
What are FeNO tests?
They measure the level of nitric oxide in the exhaled breath, providing information about the eosinophilic inflammation in the lungs
How do FeNo test results provide information about eosinophilic inflammation in the lungs?
This is due to the fact that nitric oxide is produced by inducible nitric oxide synthase (iNOS), with levels increasing in inflammatory cells – particularly eosinophils
Therefore, the level of nitric oxide correlated with the levels of inflammation.
What FeNO result indicates a diagnosis of asthma?
> 40 parts per billion
What is a direct bronchial challenge test?
It involves gradually increasing doses of medications that can irritate the airways to precipitate airway constriction
It therefore measures hypersensitivity of the airways
What three medications can be used in direct bronchial challenge tests?
Histamine
Methacholine
Mannitol
What direct bronchial challenge results indicate a diagnosis of asthma?
There are reduced medication doses required to precipitate constriction
What are the seven pharmacological management options of asthma?
Short Acting Beta-2 Agonists (SABA)
Inhaled Corticosteroids (ICS)
Long Acting Beta-2 Agonists (LABA)
Long Acting Muscarinic Agonists (LAMA)
Leukotriene Receptor Antagonists (LTRA)
Maintenance & Reliever Therapy (MART)
Oral Theophylline
Name two SABA inhalers
Salbutamol
Terbutaline
Salbutamol is what inhaler colour?
Blue
When are SABA inhalers used to treat asthma?
They are the first line pharmacological option
What is another term for SABA inhalers? Why?
Reliever inhalers
They are used to relieve acute asthma features as required
What is the mechanism of action of SABA inhalers?
Adrenalin enables relaxation of the smooth muscle in the airways
What is the main side effect of SABA?
Tremor
Name three inhaled corticosteroid inhalers used to manage chronic asthma
Beclomethasone dipropionate
Fluticasone propionate
Budeonside
Beclomethasone dipropionate is what colour of inhaler?
Brown
Fluticasone propionate is what colour of inhaler?
Purple
When are ICS inhalers used to treat asthma?
They are the second line pharmacological option
What is another term for ICS inhalers? Why?
Preventor inhalers
They should be administered by the patient every day regardless of whether the patient experiences asthma features
At what frequency should ICS inhalers be initially administered?
Twice daily
What are the two side effects of ICS inhalers?
Oral candidiasis
Stunted growth
Name a LABA inhaler
Salmeterol
When are LABA inhalers used to treat asthma?
They are the third line pharmacological option
What is another term for LABA inhalers? Why?
Preventer inhalers
They should be administered by the patient every day regardless of whether the patient experiences asthma features
What is the mechanism of action of LABA inhalers?
The adrenalin in these inhalers works to relax the smooth muscles within the airways
Name a LAMA
Tiotropium
When are LAMAs used to treat asthma?
They are the fourth line pharmacological options used to treat asthma
What is another term for LABA inhalers? Why?
Preventer inhalers
They should be administered by the patient every day regardless of whether the patient experiences asthma features
What is the mechanism of action of LAMAs?
Acetylcholine receptors are stimulated by the parasympathetic nervous system and cause contraction of the bronchial smooth muscle
LAMAs inhibit the acetylcholine receptors and therefore prevent its effects
Name an LTRA
Oral montelekast
When are LTRAs used to treat asthma?
They are the fourth line pharmacological option
What is the mechanism of action of LTRAs?
Leukotrienes are produced by the immune system to cause inflammation, bronchoconstriction and mucus secretion
LTRAs inhibit leukotrienes and therefore prevent its effects
What is MART?
It is a form of combined inhaled corticosteroid and long acting beta-2 agonist treatment in a single inhaler
How do we administer MART?
It can be administered for both daily maintenance therapy and to relieve acute asthma features as required
When do we administer MART?
It is only recommended in individuals who have poorly controlled asthma
When is oral theophylline used to treat asthma?
It is a fourth line management option
It should only be considered after trials of short/long acting bronchodilators or in those who are unable to administer inhaled therapy
What is the mechanism of action of oral theophylline?
It works by relaxing bronchial smooth muscle and reducing inflammation
Why does oral theophylline need to be closely monitored? How often do we conduct monitoring?
It has a narrow therapeutic window, therefore monitoring of plasma levels in the blood is required
This monitoring is conducted 5 days after treatment is initiated and 3 days following dose changes
What are the six stepwise management options for asthma?
Short Acting Beta-2 Agonist (SABA) Inhaler As Required
Add An Inhaled Corticosteroid (ICS)
Add A Long Acting Beta-2 Agonist (LABA)
Consider Trial of Oral LTRA, Oral Beta 2-Agonist, Oral Theophylline or LAMA
Titrate Up The Inhaled Corticosteroid (ICS) Dose. Combine Additional Treatments From Step Four
Specialist Referral
How do we determine the efficacy of asthma management?
It is based upon the patient’s clinical history, rather than a specific investigation
For example, in patients who are requiring more than three doses of their SABA inhaler per week, we would recommend that their medication is reviewed accordingly
What complication occurs when patients have a poor inhaler technique?
Oral candidiasis
What is the diagnosis when individuals present with asthma, sinusitis, haematuria and eosinophilia?
Churg’s stress syndrome
