[4] Asthma Flashcards
What is asthma?
A common lung condition that causes occassional breathing difficulties due to reversible airway obstruction
What happens when an environmental trigger is breathed in in asthma?
A type 1 hypersensitivity reaction occurs involving Th2 cells
What happens when a type 1 hypersensitivity reaction occurs in asthma?
Acute narrowing of the airway, and the classic symptoms of wheezing
What leads to the acute narrowing of the airway in asthma?
- Increased contractility of smooth muscle
- Mucosal swelling/inflammation
- Increased mucus production
What causes increased contractility of smooth muscle in asthma?
Chronic inflammation of the conducting zone of the airways, especially the bronchi and bronchioles
What causes mucosal swelling/inflammation in asthma?
Mast cell and basophil degranulation, resulting in the release of inflammation mediators
Is the narrowing reversible in asthma?
Yes, it is typically reversible with or without treatment, however occassionally the airways change
What long-term changes might occur in asthma?
- Increased eosinophils
- Thickening of the lamina reticularis
- Changes in size of airway smooth msucle
- Increase in number of mucous glands
What are the causes of asthma?
The exact cause of asthma is unknown, but several factors have been suggested as possible causes, including;
- Modern hygiene standards
- Air pollution
- Chlorine in swimming pools
- Genes
What are the risk factors for asthma?
- Family history of asthma or related atopic conditions
- Having another atopic condition yourself
- Having bronchiolitis as a child
- Exposure to tobacco smoke as a child
- Mother smoking during pregnancy
- Being born prematurely, or with a low birth weight
Give 3 examples of atopic conditions that might be associated with asthma
- Eczema
- Food allergy
- Hay fever
What is bronchiolitis?
A common lower respiratory tract infection that affects babies and young children under the age of 2
How serious is bronchiolitis?
Most cases are mild, and clear up without the need for treatment within 2-3 weeks, although some children have severe symptoms and require hospitalisation
What causes bronchiolitis?
RSV, which causes the bronchioles to become inflamed, reducing air entry into the lungs and making it difficult to breathe
What are the early symptoms of bronchiolitis?
Those of a common cold, including runny nose and cough
What symptoms develop over a few days in bronchiolitis?
- Fever
- Dry and persistent cough
- Difficulty feeding
- Wheezing
Is there any effective anti-viral for bronchiolitis?
No
How is bronchiolitis treated?
Treatment is supporive, including ensuring sufficient fluid intake, and paracetamol or ibuprofen for pain relief
What occupations are at risk of asthma?
- Paint sprayers
- Bakers and pastry makers
- Nurses
- Chemical workers
- Animal handlers
- Welders
- Food processing workers
- Timber workers
What are the potential triggers for asthma?
- Infections
- Allergens
- Airborne irritants
- Medicines
- Emotions
- Food additives
- Weather conditions
- Mold or damp
- Exercise
- Food allergies
What infections in particular can trigger asthma?
Those of the upper airway
Give 3 example of allergens that can trigger asthma
- Pollen
- Dust mites
- Animal fur
Give 3 airborne irritants that might trigger asthma
- Cigarette smoke
- Fumes
- Pollution
What medicines in particular can trigger asthma?
NSAIDs
What food additives might trigger asthma?
- Sulphites
- Tartrazine
What are the symptoms of asthma?
- Wheezing
- Breathlessness
- Chest tightness
- Coughing
When are respiratory symptoms more likely to be caused by asthma?
If they happen often and keep coming back, are worse at night and early in the morning, and seem to occur in response to a triggee
How is asthma investigated?
- History and examination
- Spirometry
- Peak flow test
- Airway responsiveness
- Testing airway inflammation
- Allergic testing
What history features increase the likelihood of asthma?
- Wheeze, SOB, and chest tightness
- Diurnal variation
- Response to exercise
- History of atopy
- Symptoms after aspirin or ß-blocker
What history features decrease the likelihood of asthma?
- Prominent dizziness, light headedness, or tingling
- Chronic productive cough with no wheeze
- Symptoms with cold only
- Significant smoking history
- Cardiac disease
What are the examination features of asthma?
- Tachypnoea
- Audible wheeze
- Hyperinflated chest
- Hyper-resonant percussion note
- Decreased air entry
- Widespread polyphonic wheeze
What are the signs of a severe asthma attack?
- Inability to complete sentences
- Pulse >110bpm
- Respiratory rate >25/min
- PEF 33-50% predicted
What are the signs of a life threatening asthma attack?
- Silent chest
- Confusion
- Exhaustion
- Cyanosis
- Bradycardia
- PEF <33% predicted
What does spirometry testing involve?
Breathing out as fast as you can through a mouthpiece attached to a spirometer
What does a spirometer measure?
The amount of air you breathe out in one second (FEV1) and the total amount of air you can hold in your lungs (FVC)
What are spirometry readings compared against?
Normal measurements for the patients age, gender, and height
How is spirometry used in the diagnosis of asthma?
Spirometry is performed, and then repeated a few minutes after taking a bronchodilator to see if results improve. If they do, this is a strong indicator of asthma.
What does peak flow testing measure?
How fast you can blow air out of your lungs in one breath
How is peak flow testing performed?
The patient breathes out as quickly and as hard as possible into a peak flow meter
What are the results of peak flow testing compared against?
The normal for someone of the same age, height, and gender
What is the advantage of patients being able to take peak flow meters home?
They can record their peak flow over a period of weeks, which can be especially helpful when asthma is suspected, but peak flow and spirometry are normal when measured
What is the purpose of airway responsiveness testing?
To test how the airways respond to an asthmatic trigger
What happens in airway responsiveness testing?
The patient will be asked to breath in a medication that will irritate the airways slightly in an asthmatic patient. They will then have a spirometry test to see if breathing has been affected.
What can be used as an alternative to medication in airway responsiveness testing?
Exercise
What is the aim of airway inflammation testing?
To determine if there is any inflammation present in the airways.
How is airway inflammation testing done?
Either by taking a mucus sample and assessing it for any signs of inflammation, or looking at the concentration of nitric oxide in an expiratory breath
What is the relevance of measuring nitric oxide in an expiratory breath?
Nitric oxide can be a sign of inflammation
When is allergy testing performed?
When there is suspicion that asthma is triggered by an allergy, but it is unknown what to do
What methods are commonly used in allergy testing?
- Skin prick test
- Blood test
How is a skin prick test performed?
How is a skin prick test interpreted?
If the patient develops a small blister within 15 minutes, it indicates they are allergic to that allergen are present
How can blood tests be used in allergy testing?
To see if substance that are produced by the body in response to an allergen is present
What are the steps in the management of an acute severe asthma attack?
- Assess the severity of the attack
- Supplemental oxgyen to maintain sats 94-98%
- Salbutamol 5mg (or terbuatline 10mg) nebulised with oxygen. If severe/life-threatening, add ipratropium 0.5mg/6hours to nebulisers
- Hydrocortisone 100mg IV, or prednisolone 40-50mg PO
- Reassess every 15 minutes
What is an assessment of the severity of an asthma attack based on?
- PEF
- Ability to speak
- Pulse rate
- Oxygen saturations
What should be done if PEF <75% after initial treatment for an acute severe asthma attack?
Should repeat salbutamol nebulisers every 15-30 minutes, or 10mg/hour continuously. Add ipratropium if not already given
Why does the ECG need to be monitored in a patient with acute severe asthma?
To watch for arrhythmia
What drug be considered for administration in a single dose in those with severe/life-threatening features that do not have a good initial response to therapy?
Magnesium sulphate 1.2-2g IV over 20 minutes
What should be done if a person is not improving after initial management for acute severe asthma?
Refer to ICU for consideration of ventilator support and intensification of medical therapy, e.g. aminophylline, IV salbutamol
What are the indications for ICU treatment in an asthma attack?
- Deteriorating PEF
- Persistent/worsening hypoxia
- Hypercapnia
- ABG showing low pH or high H+
- Exhaustion or feeble respiration
- Drowsiness, confusion, altered conscious level
- Respiratory arrest
What should be done if after treatment for acute severe asthma the person is improving within 15-30 minutes?
- Continue nebulized salbutamol every 4-6 hours
- Prednisolone 40-50mg PO OD for 5-7 days
- Monitor peak flow and oxygen saturations, aim for 94-98% with supplemental oxygen if need
- If PEF >75% 1hour after initial treatment, consider discharge with outpatient follow-up
What are the management options for chronic asthma?
- Lifestyle changes
- Patient education
- Short-acting reliever inhalers
- Preventer inhalers
- Combined preventer and long-acting reliever inhalers
