Asthma Flashcards
Define asthma?
Paroxysmal reversible obstruction of the airways due to bronchospasm and excessive secretion plugging airways.
What is the difference between early and late onset asthma? How do they clinically present?
Early onset asthma is asthma which presents in childhood and is more likely to be triggered by allergens.
Clinically it presents with episodic wheeze and a night cough.
Late onset asthma is asthma which presents in adulthood. Triggers include: Colds and viral infections Exercise Hormonal changes Irritants (smoking)
May just present with SOB an asthma attack.
Asthma associated with occupation is known as occupational asthma. It is important to identify as the trigger is found in the workplace.
Outline the common precipitants of an asthma attack?
Infections
Exercise
Allergens (House dust mite, moulds/pollen, animals, medicines)
Smoking and Cigarette Fumes
Describe the ABG findings you might see in someone with an acute asthma attack?
Initially there may be an alkalosis due to hyperventilation, Carbon dioxide will be low oxygen will be normal or low.
In severe asthma attacks the patient will start to tire therefore the respiration rate will decrease and the CO2 will be retained, eventually causing an acidosis. This will be type 2 respiratory failure.
Describe the morphology of asthma?
The airways in asthma are occluded by tenacious plugs of exudate and mucus.
There is increased inflammatory infiltrate comprising “activated” lymphocytes and eosinophils.
There is enlargement of bronchial smooth muscle, particularly in medium-sized bronchi.
What are the pathological consequences of asthma?
Complications mostly relate to acute exacerbations:
Secondary pneumonia.
Pneumothorax.
Pneumomediastinum.
Respiratory failure and arrest following an attack.
What are the clinical features of a moderate asthma attack?
Increasing symptoms
PEF >50-75% best or predicted
No features of acute severe asthma
What are the features of a severe asthma attack?
PEF less than 33-50% Respiratory rate more than 25 O2 greater than or equal to 92% HR more than 110 Cannot complete sentences in one breath
What are the features of a life threatening asthma attack?
PEF less than 33%
O2 less than 92%
Normal PaCO2
Silent chest
Decreased RR
Cyanosis
Altered consciousness
Hypotension
Bradycardia
What is in each of the following inhalers contain?
blue, brown, purple, green, orange, grey
Blue: salbutamol
Brown: beclametasone
Purple: salmeterol + fluticasone (seretide)
Green: salmeterol
Orange: fluticasone (alternative inhaled corticosteroid)
Grey: ipratropium bromide
Describe the acute management for a patient presenting with an asthma attack?
A to E assessment
Oxygen
Nebulised salbutamol 5mg given every 10 mins
All patients should receive corticosteroids:
-40mg of Prednisolone po
OR
-100mg IV hydrocortisone
If no benefit add in:
-Ipratropium nebulisers 0.5mg 4-6hrly
No improvement speak to anaesthetics/ITU:
- IV Magnesium sulphate
- IV salbutamol
- IV aminophylline
- ET tube
What is the stepwise approach used to treat non acute asthma?
Step 1: Salbutamol PRN
Step 2: INH Steroid (Betclametasone) and SABA
Step 3: Add LTRA
Step 4: LABA + SABA + ICS (cont LTRA depending on response)
Step 5: SABA + MART +/- LTRA
Step 6: Moderate dose MART
Step 7: High dose inhaled steroid (not as MART), consider referral to specialist
Describe the mechanism of action of short and long acting beta agonists?
Sympathetic: (running from a tiger, you need air)
B2 receptors stimulate bronchodilatation.
Short acting beta agonists stimulate the B2 receptors which cause cAMP to be released causing bronchodilation and help to relieve symptoms.
LABA’s work in the same way however they are used as long term preventers rather than relievers.
Describe what sort of drugs xanthine’s are? What are the important prescribing points and give examples?
They are bronchodilators. They act by inhibiting phosphodiesterase which breaks down cAMP, there is therefore more cAMP and more bronchodilatation.
Oral = theophylline IV = aminophylline (emergencys)
Note has a narrow TI, many drug interactions and may cause hypokalaemia particularly if used with B2 agonists.
Describe how glucocorticoid steroids are helpful in asthma and their mechanism of action?
Preventative:
Anti-inflammatory by activation of intracellular receptors leading to:
-altered gene transcription (decrease cytokine production)
-production of lipocortin
Lipocortin inteferes with arachidonic acid production which is involved in the production of prostoglandins and leukotrienes.
Net result reduces leukotrienes and prostoglandins.
