Asthma Flashcards
What is asthma?
Chronic inflammatory disease of airways
Airway obstruction that is reversible
Increased airway responsiveness to stimuli
What are some differentials for a wheeze?
-Acute asthma exacerbation
-bronchitis
-pulmonary oedema
-GORD
-allergy
-vocal cord dysfunction
What are some typical symptoms of asthma?
Shortness of breath
Chest tightness
Dry cough
Wheeze
What are some typical asthma triggers?
Infection
Nighttime or early morning
Exercise
Animals
Cold, damp or dusty air
Strong emotions
What is found on examination of an asthma patient typically?
Examination usually normal with a widespread polyphonic expiratory wheeze heard on auscultation
What conditions are asthma patients more likely to have?
Atopy:
-Eczema
-hay fever
-food allergies
Also FHx is strong
What drugs can worsen asthma?
B-blockers - propranolol
NSAIDS
Whats the pathophysiology of asthma?
-Airway epithelial damage - shedding and subepithelial fibrosis, BM thickening
-Infammatory reaction - eosinophils, Th2, mast cells, histamine, leukotrienes, prostaglandins
-Cytokines amplify infam response
-Increased no. Of mucus secreting goblet cells & smooth muscle hyperplasia and hypertrophy
-mucus plugging in severe asthma
What investigations are done in suspected asthma?
-Spirometry w/ bronchodilator reversibility
-Fractional exhaled nitric oxide (FeNO)
-Peak flow variability (diary) 2-4wks
-Direct bronchial challenge testing
What spirometry results would you expect in asthma?
Obstructive pattern - A FEV1:FVC ratio of less than 70%
Greater than 12% increase in FEV1 after salbutamol given
What is fractional exhaled nitric oxide (FeNO)?
measures the concentration of nitric oxide exhaled by the patient - marker of airway inflammation
-steady exhale for around 10 seconds into a device that measures FeNO
-a level above 40 ppb is a positive test result
-results less reliable in smokers
What is considered a positive result for peak flow variability?
A variability of more than 20%
Over 2-4wks
What is direct bronchial challenge testing?
-Inhaled histamine or methacholine is used to stimulate bronchoconstriction, reducing the FEV1 in patients with asthma.
-PC20 (provocation concentration of methacholine causing a 20% reduction in FEV1) of 8 mg/ml or less is a positive test result.
What are the BTS management steps of asthma?
-Short-acting beta-2 agonist inhaler (e.g. salbutamol) as required
-Inhaled corticosteroid (low dose) taken regularly
-Long-acting beta-2 agonists (e.g., salmeterol) or maintenance and reliever therapy (MART)
-Increase the inhaled corticosteroid or add a leukotriene receptor antagonist (e.g., montelukast)
-Specialist management (e.g., oral corticosteroids)
What are some additional management steps suggested for asthma patients?
-Individual written asthma self-management plan
-Yearly flu jab
-Yearly asthma review when stable
-Regular exercise
-Avoid smoking (including passive smoke)
-Avoiding triggers where appropriate
What is an acute asthma exacerbation?
Rapid deterioration in symptoms, normally caused by typical asthma triggers e.g. infection
What are some presenting features of an acute asthma exacerbation?
-Progressively shortness of breath
-Use of accessory muscles
-Raised respiratory rate (tachypnoea)
-Symmetrical expiratory wheeze on auscultation
-The chest can sound “tight” on auscultation, with reduced air entry throughout
How is acute asthma graded?
Based on presenting features:
-mild
-moderate
-severe
-life-threatening
-near fatal
What are the features of mild asthma exacerbation?
PERF >75%
No severe asthma features
What are the features of a moderate asthma exacerbation?
PERF 50-75% best or predicted
What are the features of severe asthma exacerbation?
Peak flow 33-50% best or predicted
Respiratory rate above 25
Heart rate above 110
Unable to complete sentences in one breath
What are the features of life-threatening asthma exacerbation?
Peak flow less than 33%
Oxygen saturations less than 92%
PaO2 less than 8 kPa
Becoming tired
Confusion or agitation
No wheeze or silent chest (no air entry)
Haemodynamic instability (shock)
What are the features of life threatening asthma?
Raised CO2
How is acute asthma exacerbation managed?
-ABCDE
• Aim for SpO2 94-98% with oxygen as needed, ABG if sats <92%
• 2.5-5mg nebulised Salbutamol (can repeat after 15 mins)
• 40mg oral Prednisolone STAT (IV Hydrocortisone if
PO not possible)
How are severe and life-threatening asthma exacerbations managed?
If severe:
• Nebulised Ipratropium Bromide 500 micrograms
Consider back to back Salbutamol
If life threatening or near fatal:
• Urgent ITU or anaesthetist assessment : Aminophyline
Urgent portable CXR
• Consider IV Salbutamol if nebulised route ineffective
What electrolyte must be managed with salbutamol use?
Serum potassium as salbutamol use can cause hypokalaemia
What are some criteria for safe discharge following an acute asthma exacerbation?
- PEFR >75%
• Stop regular nebulisers for 24 hours prior to discharge - Inpatient asthma nurse review to reassess inhaler technique and adherence
- Provide PEFR meter and written asthma action plan
- At least 5 days oral prednisolone
- GP follow up within 2 working days
- Respiratory Clinic follow up within 4 weeks
- For severe or worse, consider psychosocial factors
