Asthma (RESP) Flashcards
Define asthma.
Chronic inflammatory airway disease characterised by reversible, intermittent airway obstruction and hyper-reactivity
What is asthma characterised by? (3)
- bronchial hyper-responsiveness
- episodic acute asthma exacerbations
- reversible airflow obstruction
When do the symptoms of allergic asthma begin?
Childhood
What is allergic asthma associated with?
Atopy e.g.
- allergic rhinitis
- eczema
What gender is asthma more common in?
Males
Describe the pathophysiology of asthma.
- IgE-mediated type 1 hypersensitivity leading to mast cell degranulation and release of histamine
- 3 main pathological processes include:
- bronchial hyper-responsiveness
- bronchial inflammation
- endobronchial obstruction
What are the main pathological processes in asthma? (3)
- bronchial hyper-responsiveness
- bronchial inflammation
- endobronchial obstruction
What factors contribute to airway narrowing in asthma? (3)
- bronchial muscle contraction due to stimuli
- mucosal swelling/inflammation caused by mast cell and basophil degranulation leading to release of inflammatory mediators
- increased mucus production
What are some of the key features of asthma?
- recurrent episodes of SOB, chest tightness, wheezing or coughing
- characterised by an expiratory wheeze (but in severe asthma, poor air entry = chest is silent)
- may develop progressive, irreversible, obstructive lung disease
What are the clinical features of asthma? (9)
- episodic symptoms
- expiratory wheezes
- dyspnoea
- dry cough
- chest tightness
- diurnal variability of symptoms (worse at night/early morning)
- historical record of variable peak expiratory flow (PEF) or FEV1
- nasal polyposis
- recent upper respiratory tract infection
When is the dry cough in asthma worse? (3)
- at night
- with exercise
- with exposure to irritants
What are some precipitating factors/triggers for asthma?
- cold air
- viral infection
- drugs
- exercise
- emotions
- allergens - ask about dust mites, pollen, fur, pets
- smoking
- pollution
What is key in the Hx of asthma?
Symptoms come and go in response to triggers
What are some things to ask asthma patients?
- ask about previous hospitalisation due to acute asthma attacks - gives indication of severity of asthma
- ask about Hx of atopic disease:
- Semter’s Triad: asthma, nasal polyps, aspirin sensitivity
- nasal polyposis
- ask if symptoms remit at weekend - may be triggered at work (occupational asthma - main trigger isocyanate)
What are some findings on examination for asthma?
- prolonged expiratory wheeze
- tachypnoea
- use of accessory muscles
- polyphonic wheeze
- hyperinflated chest
- hyper-resonant percussion
- reduced air entry
- prolonged expiratory phase on auscultation
What are the risk factors for asthma?
- Fx
- allergens/irritants e.g. dust mites, pets
- atopic disease history (eczema, allergic rhinitis)
- cigarette smoking / vaping
- respiratory viral infection early in life
- nasal polyposis
- low socioeconomic status
When do we suspect a high probability of asthma? (5)
- recurrent episodes of symptoms (attacks)
- wheeze confirmed by a healthcare professional
- positive history of atopy
- historical record of variable airflow obstruction (spirometry)
- no features to suggest an alternative diagnosis
What do we do in patients with a high probability of asthma?
6 week trial of ICS - if there is a good response, then it can be diagnosed as asthma
What are the 1st line investigations for asthma?
- spirometry (FEV1/FVC and bronchodilator reversibility)
- peak expiratory flow (PEF)
- (FeNO test)
What results would you see on spirometry for asthma?
- FEV1/FVC ratio <70%
- bronchodilator reversibility test (BDR test): >12% in response to beta agonists (200-400mg salbutamol)/corticosteroid trial, together with an increase in volume of 200mL or more
What other investigations are considered for asthma?
- CXR (exclude other pathologies; hyperinflation)
- FBC with differential (elevated blood eosinophil count associated with severe exacerbations and poorer asthma control; neutrophilia)
- fractional exhaled nitric oxide (FeNO): >40ppb in a corticosteroid-naive adult
- bronchial challenge test (+ve)
- allergen testing (+ve for allergen)
What do other pulmonary function tests show in asthma?
- normal/raised total gas transfer (TLCO)
- raised transfer coefficient (KCO)
What is FeNO used for?
- exhaled FeNO of 40 parts per billion or more (>40ppb)
- can show degree of eosinophilic inflammation
- can be used to follow patients over time
- monitor adherence
How is occupational asthma investigated?
Serial peak flow measurements at home and work
What are the NICE recommendations for investigating asthma?
- all patients should have spirometry with bronchodilator reversibility (BDR)
- all patients should have a FeNO test
How can acute asthma attacks be classified? (4)
- moderate
- severe
- life-threatening
- near fatal
What are the features of a moderate asthma attack? (4)
- PEFR: >50-70% predicted
- normal speech
- RR <25
- pulse <110
- (treated with SABA + CS)
What are the features of a severe asthma attack? (4)
- PEFR: 33-50% predicted
- cannot complete sentences
- RR > 25
- pulse >110
- (treated with SABA + CS + monitoring)
- (normal CO2 –> life threatening attack)
What feature elevates a severe asthma attack to a life threatening attack?
Normal CO2
What are the features of a life threatening asthma attack?
- PEFR: <33% predicted
- oxygen <92%
- normal CO2
- confusion
- bradycardia
- cyanosis: PaO2<8kPa, normal/high PaCO2>4.6kPa, low pH<7.35
- CHEST - cyanosis, hypotension, exhaustion, silent chest, tachy/bradycardia
What is the distinguishing feature of near fatal asthma?
Raised PaCO2 +/- require mechanical ventilation
How is an acute asthma attack investigated and what will it show?
ABG showing type 2 respiratory failure (hypoxia + hypercapnia)
What are some differential diagnoses for asthma?
- cystic fibrosis (sweat chloride testing)
- chronic rhinosinusitis (nocturnal cough, anterior rhinoscopy)
- tracheomalacia (expiratory stridor, barking cough, bronchoscopy)
- vascular ring
- foreign body aspiration (one-sided wheezing, CXR)
- vocal cord dysfunction
- alpha-1 antitrypsin deficiency
- COPD
- bronchiectasis (dyspnoea, cough, wheeze, bronchial wall thickening CT)
- pulmonary embolism
- congestive heart failure
- common variable immunodeficiency
What are the principles of asthma management? (5)
- assess treatment adherence
- assess inhaler technique
- manage comorbidities
- manage environmental factors
- explain the importance of PEFR monitoring
What are the 5 steps for asthma symptom control? IMPORTANT
1. infrequent symptoms
- SABA (salbutamol) as needed
2. initial therapy
- SABA + low-dose ICS (beclomethasone/budesonide)
- (ICS added if symptoms >3/wk or night-time waking etc)
3. initial add-on therapy
- fixed-dose LABA (formoterol/salmeterol) + low-dose ICS + SABA as needed
- fixed-dose ICS/LABA inhaler e.g. beclomethasone/formoterol or fluticasone propionate/salmeterol
- never prescribe LABA on its own
- OR: MART LABA (maintenance and reliever therapy) + low-dose ICS (no SABA needed)
4. additional controller therapies
- fixed-dose LABA + medium-dose ICS + SABA as needed
- OR MART LABA + medium-dose ICS
- OR fixed-dose LABA + low-dose ICS + LTRA (montelukast) + SABA as needed
- OR MART LABA + low-dose ICS + LTRA
5. specialist therapies (e.g. daily steroid tablet + high-dose ICS; biologics e.g. omalizumab anti-IgE, dupilumab anti-IL4/13R, mepolizumab anti-IL5)
Describe the salbutamol inhaler.
- blue inhaler (reliever, SABA)
- tremor side effect
- taken when needed
Describe the beclomethasone inhaler.
- brown inhaler (maintainer, LABA)
- oral candidiasis side effect
- taken morning and night regardless of symptoms
What do we do if we need to step-down treatment in well-controlled asthma?
Reduce 25-50% of ICS
When do we admit an acute asthma exacerbation/attack to the hospital?
- features of severe acute asthma and failure to respond to initial treatment
- previous near fatal attack, pregnancy, attack occurring despite already using oral CS + presentation at night
How do we manage an acute asthma attack?
- supplementary oxygen if hypoxemic, target sats 94-98% (Venturi mask/nasal cannula)
- 5mg salbutamol nebulised every 15min, 100mg IV hydrocortisone OR PO prednisolone
- in children - administer nebulised ipratropium bromide + IM adrenaline
- if no improvement: 1.2-2mg IV MgSO4 over 20mins + monitor ECG (do not give for COPD exacerbation)
- if no improvement: IV aminophylline + monitor electrolytes
- no improvement: intubation + ventilation in ICU
- if improvement within 15-20mins –> nebulised salbutamol every 4h, prednisolone 40-50mg PO OD 5-7d, monitor PEFR + SpO2
- if infection, consider Abx (but often viral)
- supportive care - IV fluids if needed
Summary of escalating care during acute asthma attack.
- oxygen
- salbutamol nebulisers
- ipratropium bromide nebulisers
- hydrocortisone IV / oral prednisolone
- magnesium sulfate IV
- aminophylline / IV salbutamol
What do we do if a patient with acute asthma exacerbation has normal PaCO2?
Escalate to intensive care team as it is a sign of exhaustion + life threatening
Normal asthma attack = hyperventilating –> reducing CO2
When can a patient be discharged post-asthma attack?
- PEF > 75% predicted
- diurnal variation <25%
- inhaler technique checked
- stable on discharge for 24 hours
- patient owns PEF meter + steroids + bronchodilator therapy
What are some complications of asthma? (4)
- moderate / severe exacerbation
- airway remodelling
- oral candidiasis secondary to use of ICS
- dysphonia secondary to use of ICS
Describe the prognosis of asthma.
- many children improve as they get older
- adult onset asthma is usually chronic
