Asthma Flashcards
What are the 3 main characterisations of asthma?
Reversible airflow limitation
Airway hyperresponsiveness
Inflammation of the bronchi
What is the meaning of the term Atopy? What are atopic individuals prone to?
A genetic predisposition to IgE-mediated allergen sensitivity -
People are prone
- Allergic asthma
- Atopic dermatitis
- Allergic rhinitis
What is the Hygiene hypothesis?
Reduced exposure to infectious pathogens at a young age predisposes individuals to autoimmune and allergic disease in western countries.
What is aspirin induced asthma? What triad condition do individuals present with?
When asthma attacks can be triggered by aspirin due to a sensitivity - People have SAMTERS TRIAD
- Asthma
- Aspirin sensitivity
- Nasal polyps
What is occupational asthma?
When asthma is triggered by occupational exposures
High molecular weight
- Compounds trigger on a IgE response
- Effects are immediate as soon as person is exposed
- Flour
- Latex
Low molecular weight
- a complex immune response develops after repeated and long-term exposure
- wood dust
- isocyanates
To aid in diagnosing occupational asthma, the patient should keep a diary of what?
Peak expiratory flow diaries during periods of work and holiday
What is exercise induced asthma?
triggered by strenuous physical activity
What are key concepts in the early phase of asthma?
Inhalation of allergens causes type 1 hypersensitivity reaction in the airways
Sensitisation begins to develop causing the release of IgE antibodies
The IgE binds to mast cells
Subsequent exposure to antigen cases mast cells to degranulate and histamines to be released.
This causes smooth muscle contraction and bronchoconstriction (bronchospasm’s) whilst inflammation contributes to airway obstruction, oedema and mucous
late phase - Th2 helper cells -> B cells -> IgE & eosinophils -> • Constriction • Muco-secretion
What are key concepts in the late phase of asthma?
Early phase may be followed by late phase hours later
Inflammatory mediators are recruited (e.g. polymorphonuclear cells, T-cells)
Do beta beta agonists cause complete reversal of the late phase?
No - it is more complex
In asthma chronic inflammation occurs. How does the airway change/ respond to this?
- Fibrous tissue develops
- Airway remodelling causes airway obstruction which manifests as airway narrowing which is irreversible
What are the signs and symptoms of asthma?
Symptoms
- Cough (may be worse at night)
- Dyspnoea (SOB)
- Chest tightness
- Poor sleep
Signs
- Expiratory polyphonic wheeze
- Prolonged expiratory phase
- Tachypnoea
- Harrisons sulcus ( a groove at the inferior border of the rib cage that may be seen in children with chronic severe asthma. Also seen in rickets.)
What are the characterisation and symptoms of an asthma attack?
- Worsening of normal symptoms
- Reduction in PEF
In more severe attacks patients have signs of respiratory failure -
- Tachypnoea
- Tachycardia
- Inability to complete sentences
- Exhaustion
- Reduced respiratory effort
- Silent chest
- Altered conscious level
There are 2 main types of receptors in the airways. What are the names and what does activation of them do?
Sympathetic -> β2 receptors -> bronchodilation & mucociliary clearance
Parasympathetic -> muscarinic receptors
-> bronchoconstriction
What is the formula for flow?
Pressure change/Resistance
What is (Pouseille’s law?
resistance = 1/r4
List 5 extrinsic causes of asthma
Air pollution • Allergen exposure • Maternal smoking • Hygiene hypothesis • Genetics
List 2 key features of intrinsic asthma
Intrinsic -
- non allergic
- less responsive
Which drugs are known to trigger asthma?
Aspirin and beta blockers
Which of the many features of asthma if present make it more likely? (6)
More than one of:
- wheeze
- breathlessness
- chest tightness
- cough
variability - worse at night and in the morning
Triggered by allergies, exercise, drugs cold air
Atopic features
Family history
Low PEFR AND FEV
Features/ symptoms make asthma less likely? (8)
- Dizziness
- Peripheral tingling
- Productive cough in the absence of wheeze of breathlessness
- Consistent normal examination with breathless
- Voice disturbances
- Symptoms only with colds
Significant smoking history (>20 pack years ) - Cardiac disease
- Normal PEF or FEV1 when symptomatic
List 5 possible differential diagnosis for a wheeze
Asthma
COPD
Obstruction e.g. foreign body
Anaphylaxis
Pulmonary oedema
List the main differences between asthma and COPD
Asthma -
- Daily FEV1 variation
- Reversibility
COPD
- Older >35
- Smoking history
- Sputum production (chronic productive cough)
- Persistent/progressive breathlessness
- Variability uncommon
Which diagnostic investigations are conducted to diagnose asthma and what would the results show? (5)
Spirometry - FEV1/FVC <70% ratio
Bronchodilator reversibility -
- FEV1 pre and post beta agonist inhibition
- > 12% or 200ml improvement in FEV1
Fraction exhaled nitric oxide
normal is >25
Asthma is >40ppd
Direct challenge testing (eg
methacholine)
drop in FEV1 when exposed to provoking substance e.g. histamineor methacholine concentration required to cause 20% fall in FEV1 (PC20) OF 8mg/ml or less
Low false negative rate
Peak flow variability
Would all asthmatics have a abnormal spirometry?
Many asthmatics may have
normal spirometry especially
when not symptomatic
State 2 negative aspects of the Fraction exhaled
nitric oxide test?
Multiple confounders
1 in 5 false positive/negative rate
There are 3 extra tests which can be done for people with asthma, what are they?
◦IgE,
◦allergy/skin prick testing,
◦FBC/eosinophil count
Which life style advice is given to those with asthma?
Avoidance of triggers and allergens
Avoid smoking exposure Weight reduction • Breathing control exercises may help • Not recommended:
- House dust mite avoidance
- Air ionisers
What is the role of specialist nurses in asthma treatment?
Asthma nurse review at/shortly
after admission improves:
• Symptom control
• Self management
• Re-attendance rates
Review post discharge (< 30 days)
What should the written action plans for the self management of asthma include?
- How to use treatment
- Self monitoring/assessment skills
- Action plan with regard to goals
- Recognition and management of
exacerbations - Allergen/trigger avoidance
What is the mechanism of action for beta 2 agonists?
- Relax smooth muscle
- relieve bronchospasm
Give 2 example drugs for short acting beta agonists and long acting beta agonists?
Short acting - salbutamol, terbutaline
Long acting - salmeterol, formoterol
What are the side effects of beta 2 agonists?
o tremor
o tachycardia
o sweats
o agitation
What is the mechanism of action/ purpose of corticosteroids in the treatment of asthma?
decrease inflammation
Give 3 examples of corticosteroids used in the treatment of asthma
o budesonide
o beclometasone
o fluticasone
What the main side effects of inhaled corticosteroids?
o oral candidiasis
o systemic side effects rare with inhaled
corticosteroids
What is the mechanism of action of Leukotriene antagonists?
blocking leukotriene receptors in smooth muscle
reduce bronchoconstriction
The name the Leukotriene antagonists drug used in the treatment of asthma
Montelukast
What are the side effects if Leukotriene antagonists drugs?
nausea
headache
What is the mechanism of action for anti IgE drugs used in the treatment of asthma?
monoclonal antibody to IgE
decrease IgE
Which anti IgE drug is used in asthma treatment?
Omalizumab
What are the side effects of anti IgE drugs used in asthma treatment?
- itching
- joint pain
- headache
- nausea
Describe the progression of asthma treatment
Step 1- Low does inhaled corticosteroids
Step 2- Inhaled LABA plus inhaled corticosteroid
Step 3- Responds to LABA? - Continue but increase inhaled corticosteroid to medium dose
Does not respond to LABA? Stop LABA increase inhaled corticosteroid dose
Or ADD Leukotriene receptor agonist or SR theophylline or long acting muscarinic receptor agonist
Step 4 - Increase inhaled steroid to high dose
Add fourth drug (leukotrien, theophyline, beta agonist, long acting muscarinic)
Refer patient to specialist
Step 5 - Daily steroid tablets - lowest dose
Continue high dose inhaled corticosteroids
- consider other treatments to minimize steroid use
Refer patient to specialist
List 12 precipitating factors for an asthma attack
- Pollen
- Bugs in the house
- Chemical fumes
- Cold air
- Fungus spores
- Dust
- Smoke
- Strong odors
- Pollution
- Anger
- Stress
- Pets
- Exercise
What are the 5 names used to categories asthma attack severity
- Near fatal
- Life threatening
- Acute sever
- Moderate
- Brittle
What is brittle asthma? - there are 2 types
Type 1 - Wide PEF variability (>40% diurnal variation for >50% of the time over a period >150 days) despite intense therapy
Type 2 - sudden severe attacks on a background of apparently well-controlled asthma
What is moderate asthma exacerbation?
- Increasing symptoms
- No features of acute sever asthma
- PEF> 50-75% best or predicted
What is acute sever asthma exacerbation?
Any one of -
- PEF 33-50% best or predicted
- Resp rate > 25/min
- Heart rate > 110
- Inability to complete sentences when breathing
Patient must be admitted
What is life threatening asthma exacerbation? (13)
Think 33, 92, CHEST
One of the following
- PEF <33% best or predicted
- SpO2 <92%
- PaO2 <8 kPa
- normal paCO2 (4.6-6.0 kPa)
- Silent chest
- Cyanosis
- Feeble respiratory effort
- Bradycardia
- dysrhythmia
- hypotension
- Exhaustion
- Confusion
- Coma
Call Call anaesthetist
What is near fatal asthma exacerbation?
Raised PaCO2 and/or requiring mechanical ventilation with
raised inflation pressures
When should a patient be discharged after being admitted with an asthma attack?
PEF >75% after 1 hour, unless:
Significant symptoms Compliance concerns Lives alone Psychological/physical/learning problems Previous near fatal or brittle asthma Pre-existing steroids Night time Pregnant
When a patient has been admitted with asthma which treatment would they be given?
ABCDE approach
Oxygen
- High flow (aim >92% - 94-98%)
- Give O2 driven nebulisers
IV fluids
- Rehydration
- Correct electrolyte imbalances
Drugs - Salbutamol - Hydrocortisone - Ipratropium bromide - Theophylline - Magnesium sulphate Reassess - every 15mins with PEFR
How should salbutamol be administered in someone hospitalised with asthma?
Nebulised with oxygen -
2.5-5mg every 10 minutes
How are the side effects of nebulised salbutamol?
Tremor
Arrhythmias
Hypokalaemia (monitor ECG)
Why should the ECG of a patient being treated with nebulised salbutamol be monitored?
Hypokalaemia (monitor ECG)
How should hydrocortisone be administered in someone who has been hospitalised with asthma?
IV 100-200mg QDS
Corticosteroid
Prednisolone PO 40mg OD
Can cause systemic side effects
How should Ipratropium bromide be administered in someone who has been hospitalised with asthma?
Nebulised with oxygen
500 micrograms every 4-6 hours
What type of drug is Ipratropium bromide?
Muscarinic receptor antagonist
How should Magnesium sulphate be administered in someone who has been hospitalised with asthma?
1.2 – 2 grams over 20 minutes IV
Acute severe asthma
What is the mechanism of action for Theophylline? When should the drug be used?
Inhibit phosphodiesterase and increase cAMP
Life-threatening asthma with
Senior guidance
What are the side effects of Theophylline?
Palpitations
Arrhythmias
Nausea
Seizures
Alkali burns if extravasation occurs
Drug interactions
When should ITU be involved in a patients treatment of asthma at hospital?
In ventilatory support required
Life threatening / acute severe not improving
After treating a patient in hospital with sever asthma, what should you continue to monitor while they are in hospital?
Regular peak flow
Oxygen saturation
ABG- Repeat at 1 hour if:
Hypoxic
Normo-hypercapnoeic
Patient deteriorates
Bloods-
Potassium
Glucose
ECG -
K+ ; Mg 2+ ; b2
After being discharged from hospital due to a sever asthma attack how often should a patient be followed up?
Follow up Within 48h (can be by hospital, GP, nurse
Follow up again in <30days after discharge by GP or specialist nurse or respiratory clinic appointment
In someone having an acute asthma attack and has been admitted to hospital - what is the first line treatment
- Salbutamol, oxygen, steroids
ipratropium bromide
In someone having an acute asthma attack and has been admitted to hospital - what is the second line treatment
- Magnesium sulphate
beta 2 antagonist infusion (those not responding)
Aminophylline/ theophylline - levels should be checked daily
