Asthma Flashcards
What is asthma?
a chronic inflammatory disorder of the airways
What 2 effects does asthma have on the airway?
- airway hyper-responsiveness (of smooth muscle)
2. variable airflow obstruction that is often reversible either spontaneously or with treatment
What are the 4 main risk factors for asthma?
- Genetic
- Maternal atopy
- Maternal smoking
- Obesity
What is maternal atopy?
it occurs when the mother has a tendency to be “hyperallergic”
they often present with 1 or more from eczema, allergic rhinitis or allergic asthma
What are the 2 protection factors from asthma?
- breast feeding
2. early exposure to animals
What is extrinsic asthma?
Extrinsic asthma is triggered by external causes
When does extrinsic asthma usually start?
It has a strong family history and starts in childhood
What do people with extrinsic asthma also normally present with?
Eczema and/or rhinitis
Skin tests for other allergens are usually positive
How do the symptoms of extrinsic asthma vary?
Symptoms are episodic and can be brought on by precipitating factors
When does intrinsic asthma usually begin and what are the precipitating factors?
Begins in adulthood
No clear precipitating factors but some sufferers are sensitive to aspirin
Describe the symptoms of intrinsic asthma?
Persistent symptoms which are not worsened by external factors
Exacerbated by infections
What do skin tests show in patients with intrinsic asthma?
skin tests for other allergens are negative
What is meant by asthma increasing basal tone?
Increased smooth muscle contraction which will constrict the airway
How does asthma affect mucous secretion?
Hypersecretion of mucous and mucosal oedema
What is mucosal oedema?
build-up of fluid within the tissue that lines the body’s interior (mucosa)
What can mucosal oedema lead to?
Interstitial oedema where fluid enters the interstitial spaces of the lung
How do symptoms of asthma vary?
Tend to be variable, intermittent and provoked by triggers
Symptoms are often worse at night
What are the 8 main symptoms of asthma?
- Polyphonic wheeze
- Tachypnoea
- Chest tightness
- Coughing - particularly at night and early morning
- difficulty sleeping
- chest pain
- vomiting
- tremor/hoarse voice
Why does asthma cause a hoarse voice?
Due to thrush in the mouth which is a side effect of a steroid inhaler
Why does asthma cause a tremor?
The inhaler contains albuterol
Albuterol is a B agonist that can cause tachycardia
How will FEV1/FVC ratio vary in asthma patients?
Asthma is obstructive so FEV1/FVC ratio will be reduced
How is asthma monitored?
Take 2 peak flow readings daily and make a peak flow chart
Peak expiratory flow (PEF) will show >20% diurnal variation on at least 3 days in 2 weeks
How do the accessory muscles of respiration change in asthma?
They are usually only used during exercise or when particularly out of breath
They are active in asthma patients
What is a paradoxical pulse?
During inspiration the pulse will fall and it will rise during expiration
paradoxical pulse consists of a large decrease in systolic blood pressure and pulse wave amplitude during inspiration
What are the 2 main categories of asthma treatments?
relievers and preventers
What is the role of the reliever “beta2 adrenoceptor agonist”?
stimulates beta2 adrenoceptors in the airway
this leads to relaxation of bronchial smooth muscle
What are examples of beta2 adrenoceptor agonists?
salbutamol, terbutaline, salmeterol and efomoterol
What is the role of antimuscarinic relievers?
Inhibit muscarinic receptors on smooth muscle
Leads to relaxation of bronchial smooth muscle
What are examples of antimuscarinic relievers?
ipratropium bromide and tiotropium
What is the role of glucocorticoids as preventers?
Bind to cytosolic receptors and affect gene transcription and translation
Leads to potent anti-inflammatory agents and reduced airway hyper-responsiveness
What are examples of glucocorticoid preventers?
hydrocortisone, prednisolone, beclomethasone, budesonide, flucticasone
What are the 4 other treatments used for asthma?
- leukotriene antagonists
- magnesium IV for acute asthma
- theophyllines IV
- monoclonal antibodies
For acute severe asthma, what would PEF, respiration and pulse look like?
PEF - 33-50% of best
Can’t complete sentences in one breath
Respiration >/= 25 breaths per min
Pulse >/= 110 beats per min
What are the life threatening features of asthma?
What is PEF and SpO2?
silent chest, cyanosis or feeble respiratory effort
arrhythmia or hypotension
exhaustion or altered consciousness
PEF < 33% of best
SpO2 < 92%
What are the features of near-fatal asthma?
Raised PaCO2
Requiring mechanical ventilation with raised inflation pressures
When looking at blood gases of an asthmatic, how does pCO2 vary?
pCO2 lower than expected in a normal individual
CO2 levels are lower in asthmatics due to increased hyperventilation
What is a severe warning sign for severe asthma?
Patient is still breathless after being given oxygen
What is normal pO2 in arterial and venous blood?
arterial - 11-13 kPa
venous - 5 - 5.6 kPa
What is normal pCO2 in arterial and venous blood?
arterial - 4.7-5.9 kPa
venous - 5.6 - 6.7 kPa
What is normal pH in arterial and venous blood?
arterial - 7.36 - 7.44
venous - 7.34 - 7.42
What steps should be taken to follow up on asthma patients?
- check compliance with existing therapies
- check inhaler technique
- education and asthma plan
- look for triggers in a new patient and eliminate trigger factors
