Asthma Flashcards
What is asthma?
Chronic inflammatory airway disease -> variable airway obstruction
What is affected in asthma?
Smooth muscle in airways is hypersensitive
Is asthma reversible?
The bronchocontriction is reversible with bronchodilators, such as inhaled salbutamol
When does asthma present?
Typically in childhood, but can be any age
How does asthma present?
Episodic symptoms
Diurnal variability
Symptoms =
-SOB
-Chest tightness
-dry cough
-wheeze
Symptoms should improve with bronchodilators
Key findings = widespread polyphonic expiratory wheeze
What do people with asthma typically have a history of?
Other atopic conditions
A FHx of asthma or atopy
What are the triggers of asthma?
Infection
Nighttime or early morning
Exercise
Animals
Cold, damp or dusty air
Strong emotions
What investigations are done?
Spirometry
PeNO
Peak flow variability
Direct bronchial challenge testing
Describe how Spirometry can be used
Establishes objective measures of lung function
FEV1 : FVC ratio < 70% => obstructive pathology
Reversibility test = give a bronchodilator before repeating Spirometry
- greater than 12% increase in FEV1 on testing = asthma
Describe how FeNO is used in asthma?
Measures the conc of NO exhaled
NO = marker of airway inflammation
>40ppb = +ve test result
Smoking decreases FeNO => unreliable
How is peak flow variability used?
Keep peak flow diary with readings at least twice daily over 2 to 4 weeks
Peak flow variability > 20% =+ve result
How is direct bronchial challenge testing used?
Inhaled histamine or metacholine stimulates bronchocontriction => decreased FEV1 in asthma
How is a diagnosis made with asthma?
FeNO + Spirometry + bronchodilators reversibility
If uncertain:
Peak flow variability Direct
What are the drug groups used to treat asthma?
Beta - 2 - adrenergic receptor agonist
Inhaled corticosteroids
Long term muscarinic antagonist
Leukotriene receptor antagonist
Theophylline
Maintenance and reliever therapy
What is the action of beta -2- adrenergic receptor agonists?
Bronchodilators
Adrenalin acts on smooth muscle of airways causing relaxation
Adrenaline receptor stimulation -> bronchiole dilation
What are the different types of B2ARA?
SABA
LABA
How are Saba used?
Work quickly, but only last a few hours => reliever/rescue medicine during acute worsening of asthma symptoms
Salbutamol
How are LABA used?
Slower, but last longer
Salmeterol
What is an example of an ICS?
Beclametasone
What do ICS do?
Reduce inflammation and reactivity of airways
How are ICS used?
Used as maintenance or preventor medication to control long term symptoms
Taken regularly, even when well
What is an example of LAMA?
Triotropium
How do LAMAs work?
Block acetylcholine receptors
These are stimulated by parasympathetic nervous system -> contraction of bronchial smooth muscles
=> blocking receptors dialate bronchioles
What is an example of leukotreine receptor antagonist?
Montelukast
How do leukotreine receptors antagonists act?
Blocks leukotrines effects
-produced by immune system
-cause inflammation, bronchioconstriction and mucous secretion in airways
How do theophylline act?
Relax bronchial smooth muscles and reduce inflammation
Narrow therapeutic window
Toxic in excess
What is maintenance and reliever therapy?
Combo inhaler
-ICS
- fast and long acting beta agonist
What is the sign guidelines for long term management?
- SABA as required
- ICS taken regularly (low dose)
- LABA or MART
- Increase ICS or add LRA
- Specialist management
What additional management can be used?
Individual written asthma self management plan
Yearly flu jab
Yearly asthma review
Reg. exercise
Avoid smoking
Avoid triggers
What are features of acute exacerbation?
Increased SOB
Use accessory muscles
Increased respiratory rate
Symmetrical expiratory wheeze
Chest sound “tight”
What is the arterial blood gas analysis in acute exacerbations?
Respiratory alkalosis
Increased pCO2 or reduced pO2 = concerning sign
Respiratory acidosis due to increased pCO2 = BAD sign
How is acute asthma graded?
Mild
Moderate
Severe
Life threatening
What is criteria of moderate grading?
Peak flow 50-75% best or predicted
What is criteria of severe?
Freak flow of 33-50%
Respiratory rate > 25
Heart rate > 110
Unable to complete sentences
What is criteria of life-threatening?
Peak flow <33%
Ox sat <92%
PaO2 <8kPa
Becoming tired
Confusion or agitation
No wheeze/ silent chest
Haemodynamic instability
What is the management of mild asthma?
Inhaled beta-2-agonist via spacer
X4 dose of ICS
Oral steroids if ICS inadequate
Antibiotics if evidence of bacterial infection
Follow up in 48hrs
What is the management of moderate asthma?
Consider hospital
Nebulised beta-2-agonist
Steroids
What is the management of severe asthma?
Hospital admission
O2 to maintain sats 94-98%
Nebulised ipratropium bromide
IV mg sulphate
IV salbutamol
IV aminophylline
What is the management of life-threatening asthma?
Admit to HDU or ICU
Intubate and ventilate
What should be done after the attack?
Optimise long term management
Individual written asthma self management plan
Rescue pack of oral steroids
Refer to specialist if 2 attacks in 12 months
