Asthma Flashcards
Define the classical features of asthma
(symptoms and signs)
Ashthma is a chronic inflammation condition of the airways, charactised by airway hypersensitivity to a number of factor.
Symptoms variable but recurring:
- Reverisible bronchospasm resulting in airway obstruction:
- Wheezing & SOB
- Classically worse during night or upon exercise
- Symptoms are typically worse in the morning (peak flow worse - ‘morning dipping’)
- Subjective feeling of chest tightness
- Cough, again classically nocturnal
Signs:
- Widespread expiratory wheeze
- Pulmonary function testing reveals a decreased FEV1 (peak flow) relieved by ß2 agonists
Classify asthma into early and late onset and discuss the likely presenting characteristics of a typical patient who is likely to get each
Extrinsic asthma
- Type I hypersensitivity reaction
- ay occur in young patients with atopy (alergic diseases)
- Elevated IgE may be present, alongside eczema and/or rhinitis
- May disappear at age 15 but may recur.
Intrinsic asthma
- Non-immune mechanisms
- occurs in middle aged, with no causative agent can be identifie (no history of atopy - allergies)
- Skin tests are usually negative and IgE normal, remission is rare.
- They may present with shortness of breath and tight chest - more severe symptoms and associated with quicker deterioations in lung function
Outline common precipitants of an asthma attack
Common precipitants:
- Environmental allergens: pets, grass pollen, dust mites
- Viral infections
- Cold air
- Emotion
- Drugs: NSAIDs particularly aspirin. Beta-blockers
- Atmospheric pollution
- Occupational pollutants: e.g. flour or chemicals
How may the symptoms of asthma be differentiated from those of COPD?
In asthma airflow limitation is often fully reversible, either spontaneously or with treatment whereas COPD is a disease of progressive airflow limitation that is not fully reversible.
What occupations may predispose to developing asthma?
Vehicle spray painting, woodworking, baking, soldering, healthcare workers, working with animals, working in agriculture, engineering, hairdressing
Describe the clinical features of an acute asthma attack
Features of acute severe asthma:
- Tachycardia (HR > 110)
- Marked SOB (RR>25)
- Peak expiratory flow (PEF) 33-50% of best
- Cant complete sentences in one breath
May have pulsus paradoxus (abnormally large decrease in systolic BP during inspiration)
- Widespread bilateral expiratory wheeze in a hyper inflated chest
- Accessory muscle of respiration are often used
Describe the clinical features of life threatening asthma attack
-PEF less than 33% of best -SpO2 <92% -Silent chest, cyanosis or feeble respiratory effort -Bradycardia, hypotension or dysrhythmia -Exhaustion or confusion
Describe the blood gas abnormalities associated with severe asthma and highlight other clinical indices of severity
- In a mild attack, there may be low pCO2
- Due to hyperventilation
- A normal pCO2 with hypoxaemia suggests current deterioration (life threatening attack)
- In life threatening exacerbations there will be a high pCO2, severe hypoxia and low pH.
- PEF<50% indicates severity, and <33% life-threat.
Describe how to use inhaler devices and other aids appropriately
Shake the inhaler, take a normal breath out, place the inhaler in your mouth and simultaneously breathe in and press the button to release the aerosol.
Hold the breath in for 10 seconds if possible.
Important not to just spray the inhaler into the mouth!
With the steroid inhaler, the patient should be counselled to rinse the mouth out after use.
Describe the morphology and pathological consequences of acute asthma
Asthma is an inflammatory condition with both acute and chronic elements.
Acute asthma:
- Acute episodes of bronchospasm that are triggered by recognised triggers
- These triggers activate mast cells, which lead to two phases;
-
An early phase of bronchospasm due to spasmogen production (histamine, prostaglandin D2 and leukotrienes)
- smooth muscle contraction narrows the airway
-
A late phase due to chemotaxins attracting eosinophils and mononuclear cells
- cells infiltrates and muscosal oedema narrow the airway.
- There will also be airway hyper-reactivity in the late phase, which can lead to further acute deteriorations
-
An early phase of bronchospasm due to spasmogen production (histamine, prostaglandin D2 and leukotrienes)
Describe the morphology and pathological consequences of chronic asthma
Asthma is an inflammatory condition with both acute and chronic elements.
Chronic asthma
- Many asthmatics will have normal respiratory function between attacks, but some will develop persistent airway obstruction that can become indistinguishable from COPD (more common in intrinsic asthma)
- There is bronchoconstriction due to increased responsiveness of bronchial smooth muscle, and hyper secretion of mucus that plugs the airways
- Mucosal oedema further narrows the airways
- The sputum will contain Charcot-Leyden crystals (from eosinophil granules) and Curschman spirals (mucus plugs from small airways)
- In long-standing disease, the can lead to pulmonary hypertension
What are these:
- FEV1
- FVC
- KCO
- TLCO
What is obstuctive and restrictive pattern involving FEV1 and FVC?
-
FEV1 = forced expiratory volume
- Volume that has been exhaled at the end of the first second of forced expiration
- FVC = focred vital capacity
Volume that has been exhaled after a maximal expiration following a full inspiration
- KCO = Diffusion capacity of the lung per unit area for CO
- TLCO = Diffusion capacity of the total lung capacity for CO
Obstructive pattern:
- Normal (or increased) FVC, reduced FEV1:FVC ratio
Restriction pattern:
- Reduced FVC, normal (or increased) FEV1:FVC ratio
How can you obtain an accurate peak flow rate (PEFR) from a patient
Stand tall, deep breath, encourage, and take the best of 3.
