Asthma Flashcards
What is the definition of asthma
- a combination of cough, wheeze or breathlessness with variable airflow obstruction
what type of disease is asthma
Heterogenous disease usually characterised by chronic airway inflammation
what are the 4 symptoms of asthma
- wheeze
- shortness of breath
- chest tightness
- cough
- with evidence of variable airflow limitation - its reversible
How many people does asthma affect
◦5.4 million people in the UK receive treatment for asthma: 1 in 11 children and 1 in 12 adults
◦Affecting 1 – 18% of the population of different countries
what is a phenotype
A phenotype is defined as the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
Name the 5 differnet phenotypes of asthma
◦Allergic asthma ◦Non-allergic asthma ◦Adult-onset (late-onset) asthma ◦Asthma with persistent airflow limitation ◦Asthma with obesity
Describe allergic asthma
- asthma due to allergies
- has lots of eosinophils
describe non allergic asthma
- more neutrophil based
- do not have an allergen that triggers asthma
- not responsive to steroids
Describe adult-onset asthma
- can be due to occupational asthma - working in a bakery or a factor
describe asthma with persistent airflow limitation
- due to chronic inflammation that has become irreversible
what receptors cause bronchodilation
- sympathetic = b2 receptors - these cause bronchodilator and mucocillary clearance
what receptors cause bronchoconstriction
- Parasympathetic = muscarinic receptors and causes bronchoconstriction
What holds the large airways open
- Cartilage holds the large airways open
How do you work out flow
pressure change/resistance
what causes an increase in flow
- increased pressure change
- or decreased resistance (pouseille’s law: resistance 1/r4)
Describe the pathology of asthma
Inflammatory process:
- obstruction
- airway hyper-responsiveness
Describe what happens in the acute and late phase pathology of asthma
Acute phase: Mast cells cause - bronchospasm - oedema - mucous
Late phase
TH2 helper cells cause B cells to be produced and this causes IgE and eosinophil production this leads to:
- constriction
- muco-secretion
What are the extrinsic, intrinsic and occupational causes of asthma
Extrinsic
- air pollution
- allergen exposure
- maternal smoking
- hygiene hypothesis
- genetics
Intrinsic
- non allergic
- less responsive
- colds/infections
Occupational
- allergens at work
how can you diagnose asthma
- no single diagnostic test
- clinical assessment supported by objective evidence of variable airflow obstruction or airway inflammation
What are the features that make asthma more likely
More than one episode of
- wheeze
- breathlessness
- chest tightness
- cough
Variability
- worse at night and in the O-ring (diurnal variability)
- trigged by allergen, exercise, cold air, aspirin or beta blocker
- atomic features
- family history of asthma/atopy
- objectively auscultated wheeze on clinical examination
- low PEFR or FEV
why do you produce NO in asthma
- due to high eosinophils which help activate NO producing
- eosinophils use inducible nitric oxide synthetase (iNOS) to produce NO
What are the differential diagnosis of asthma
- COPD
- Obstruction due to a foreign body
- anaphylaxis
- pulmonary oedema
What are the differences between Asthma and COPD
Asthma
- reversible
- daily FEV1 variation
- can be related to eosinophils and allergies
COPD
- older
- smoking history
- sputum production
- not reversible
what is the treatment difference between asthma and COPD
Asthma is chronic inflammation so you use a higher dose of steroids whereas COPD you use lower doses of steroids
Name the ways in which you can measure asthma
- spirometry
- fraction exhaled nitric oxide (FENO)
- Direct challenge testing (e.g. methacholine)
- peak flow variability
What does spirometry measure
- FEV1/FVC
what is the diagnostic result of asthma in spirometry
- FEV1/FVC less than 70%
How can bronchodilators reversibility prove asthma
- FEV1 is measured pre and post beta agonist (salbutamol) inhalation with a spirometry
- if there is an improvement of 12% or 200ml in FEV1 then it shows that there is asthma
How can FENO show asthma
- Breath test - marker of eosinophilic inflammation
- greater than 40ppb
- multiple confounders
- 1 in 5 have a false positive/negative
How does a direct challenge testing show asthma
- Drop in FEV1 when exposed to provoking substance such as histamine or methacholine
- concentration required to cause 20% fall in FEV1 (PC20) of 8mg/ml or less
- low false negative rate
- 2/3rds with positive test have asthma
describe how peak flow shows asthma
- twice daily readings over 2 weeks - diurnal variation
- should show 20% variability in PEF
What other tests can be helpful for diagnosing asthma
- IgE
- allergy/skin prick testing
- FBC/eosinophil count
How do you treat asthma
- avoidance of triggers and allergens
- medical
What lifestyle advice should be given for asthma
- Avoid smoking exposure
- Weight reduction
- Breathing control exercises may help
• Not recommended:
o House dust mite avoidance
o Air ionisers
What do specialists nurses do in the management of asthma (MENTION IN THE OSCE THAT SPECIALIST NURSES DEAL WITH ASTHMA)
Asthma nurse review at/shortly after admission improves
- symptom control
- self management
- re-attendance rates
- Review post discharge within 30 days
What does a self management plan 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 recovery medication for asthma
- short acting B2 agonists - salbutamol
What is the mechanism of action of salbutamol
- relax smooth muscle
- receive bronchospasm
Give examples of short acting B2 agonists
- Salbutamol
- terbutaline
Give examples of long acting B2 agonists
- salmeterol
- formoterol
what are the side effects of B2 agonists
- tremor
- tachycardia
- sweats
- agitation
What is the mechanism of action of corticosteroids
- decrease inflammation
Name examples of corticosteroids for asthma
- budesonide
- beclometasone
- fluticasone
What are the side effects of corticosteroids in the treatment of asthma
- oral candidiasis - IN OSCE MENTION THEY HAVE TO WASH THERE MOUTH AND THE INHALER AFTERWARDS TO PREVENT THIS
- systemic side effects rare with inhaled corticosteroids
How to leukotriene antagonists work
- block leukotriene receptors in smooth muscle this reduces bronchoconstriction
Name an leukotriene antagonists
- Montelukast
What are the side effects of leukotriene antagonists
- nausea
- headache
what line is luekotreine antagonists in the treatment of asthma
2nd line after corticosteroids in NICE guiltiness
3rd in BTS guidelines
describe how anti IgE is used as a treatment form asthma
- monoclonal antibody to IgE
- decreases IgE
What is an example of anti IgE
- omalizumab - given SC
what are the side effects of anti IgE
- itching
- joint pain
- headache
- nausea
- anaphylaxis
What do you need to consider when giving IgE
- confirmed allergic IgE-mediated asthma as an add-on to optimised standard therapy
- continuous or frequent treatment with oral corticosteroids (defined as 4 or more courses in the previous year)
describe the BTS and NICE guidelines for treatment of asthma
BTS
- low dose ICS
- add inhaled LABA to low dose ICS
- increase ICS to medium dose or add an LTRA
- refer patient to specialist care
NICE
- low dose ICS
- offer LTRA
- Add LABA
- MART then increase ICS in MART or fixed dose ICS/LABA and SABA then LAMA or theophylline
describe what should happen with the dosage of corticosteroids
- patients should be maintained at the lowest possible dose of inhaled corticosteroids
- reduction of about 25-50% each time should be considered every 3 months
What is the definition of uncontrolled asthma
• 3 or more days a week with symptoms or
• 3 or more days a week with required use of a SABA for symptomatic
relief or
• 1 or more nights a week with awakening due to asthma.
How should you assess the risk of future attacks
Ask about history of previous attacks, objectively assessing current asthma control, and reviewing reliever use
- In children, regard comorbid atopic conditions, younger age, obesity, and exposure to environmental tobacco smoke as markers of increased risk of future asthma attacks
- In adults, regard older age, female gender, reduced lung function, obesity, smoking, and depression as markers of a slightly increased risk of future asthma attacks
how does the asthma control test work
- The scores range from 5 (poor control) to 25 (complete control)
- An ACT score >19 indicates well-controlled asthma.
what are the severity levels of asthma
- Near-fatal
- Life-threatening
- Acute severe
- Moderate
- Brittle
what is the difference between type 1 and type 2 brittle asthma
- 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
Describe what moderate asthma looks like
- respiration rate less than 25/min
- pulse less than 110 bpm
- PEF greater than 50-75% best or predicted
- speech normal
- no features of acute severe asthma
Describe what acute severe asthma looks like
Any one of:
- PEF 33-50% best or predicted
- respiratory rate is greater than 25/min
- heart rate is 119 bpm or greater than 110 bpm
- inability to complete sentences in one breath
Admit if persisting symptoms
What does life threatening asthma look like
Any one of the following in a patient with severe asthma:
- PEF less than 33% best or predicted
- SpO2 less than 92%
- PaO2 less than 8kPa
- normal PaCO2 (4.6-6kPa)
- silent chest
- cyanosis
- feeble respiratory effort
- bradycardia
- dysrhythmia
- hypotension
- exhaustion
- confusion
- coma
- call an anaesthetist
- 33-92 chest (PEF <33%, sats <92%, cyanosis, hypotension, exhaustion, silent chest, tachy or bradycardia)
What does near fatal asthma look like
Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures
who do you admit in an asthma attack
- life threatening attack
- severe attack that does not response to initial treatment
Other admission criteria include
- previous near fatal asthma attack, pregnancy, an attack occurring despite already using oral corticosteroid and presentation at night
Who do you discharge after an asthma attack
PEF greater than 75% after 1 hour unless
- significant symptoms
- compliance concerns
- lives along
- psychological/physical/learning problems
- previous near fatal or brittle asthma
- pre-existing steroids
- night time
- pregnant
How do you treat acute asthma
ABC
Oxygen
- aim stats of greater than 92%
- Oxygen driven nebuliser
- if acutely unwell = 15L supplemental via a non rebreathe mask
Bronchodilation with short acting beta 2 agonists (SABA)
- High dose inhaled SABA
- in patients without life threatening or near fatal asthma this can be given by a standard inhaler or nebuliser
- if patient has life threatening asthma then nebulised SABA
Corticosteroids
- 40-50mg of prednisolone orally daily which should be continued for at least 5 days or until the patient recovers from the attack
IV fluids
- rehydration
- correct electrolyte imabalance
reassess
- every 15 minutes with PEFR
What drugs do you give in actue asthma
OSHITP
- Oxygen
- Salbutamol
- Hydrocortisone/Prednisolone
- Ipratropium bromide
- Theophylline
- ! Magnesium sulphate
How do you give salbutamol in acute asthma
Nebulised with oxygen
2.5-5mg every 10 minutes
What are the side effects of using salbutamol in an acute asthma attack
- Tremor
- Arrhythmias
- Hypokalaemia (monitor ECG)
How do you give hydrocortisone in acute asthma
IV 100-200mg QDS
Or prednisolone PO 40mg OD
How do you give ipratropium bromide
Nebulised with oxygen
500 micrograms every 4-6 hours
- given in patients who do not respond to SABA or corticosteroid
What are the side effects of nebulised ipratropium bromide
- Arrhythmias
- cough
- dizziness
- dry mouth
- headache
- nausea
Who and how do you give magnesium sulphate to in an acute asthma
- 1.2 – 2 grams over 20 minutes IV
- Acute severe asthma/ life threatening asthma
Who do you give theophylline to and what does it do
- Inhibit phosphodiesterase and increase cAMP – smooth muscle
- Life-threatening asthma
- senior guidance
What are the side effects of theophylline
- Palpitations (chronotropic effect)
- Arrhythmias (chronotropic effect)
- Nausea
- Seizures (stimulates CNS)
- Alkali burns if extravasation occurs
- Drug interactions
When do you involve ITU
- All patients requiring ventilatory support
- Near fatal asthma
Life threatening / acute severe not improving
• Worsening peak flow
• Persistent/worsening hypoxia • High PaCO2
• Low pH
• Exhaustion
• Drowsiness
• Respiratory arrest
How do you monitor acute asthma
- regular peak flow
- oxygen saturations and chest auscultation
ABG Repeat at 1 hour if: - hypoxic - normo-hypercapnoeic - patient deteriorates
Bloods
- potassium
- glucose
ECG
- potassium
- magnesium
- B2
what is the discharge planning after an acute asthma attack
Improved symptoms
◦ clinical signs compatible with home management
◦ β2-agonist requirements
◦ therapy can be continued at home
Improved peak flow
◦ >75% best/predicted
◦ <25% diurnal variation
Follow up
o within 48 hrs
o <30 days post discharge by GP/nurse specialist
o under specialist supervision indefinitely for near-fatal asthma and
at least 1 yeat for severe asthma attack
Do these OSCE examples
- Explain to a patient the difference between a reliever and preventer inhaler
- Demonstrate the use of metered dose inhaler with and without a spacer to a patient
Do it
What is the differential diagnosis for wheeze
- asthma
- allergies
- GORD
- infection
- obstructive sleep apnoea
How do you diagnose occupational asthma
- PEF taken at home and at work and compared
What measures can be taken to prevent and treat occupational lung disease
- avoid the inhaled substances that cause the lung disease
- PPE
