Asthma Flashcards
What is asthma?
A chronic inflammatory disorder of the bronchial mucosa that causes bronchial hyper responsiveness, constriction of the airways and variable airflow obstruction that is reversible
What is Atopic (extrinsic) causes of asthma
Avoidable..triggers ..The environment - allergens (pollen, pets, dustmites), mould, cold or dry air, perfumes, medications (aspirin, NSAIDS, beta blockers)
Dietary (foods, chemicals, additives)
* inflammation mediated by systemic IgE production
What are non-atopic (intrinsic) triggers for asthma
These are unavoidable triggers such as exercise, laughter, URTI, co-morb medical conditions (gord, obesity, allergic rhinitis, upper airway dysfunction)
Extreme emotions
Hormonal changes
Pregnancy
* inflammation mediated by local IgE production
Sexual activity
Early clinical manifestations of asthma
Speaking in sentences or moderate phrases
Chest tightness
Exploratory wheeze and prolonged expiratory
Non productive dry cough
Tachycardia
Tachypnoea
Anxious and agitated
Clinical manifestations of a severe asthma attack
Increased WOB (use of accessory muscles) RR >60 Speaking in words only pefr <40% Sats <90% Nasal flaring Distressed Wheeze on inspo and expo Pulsus paradoxus (drop in systolic BP during inspo) Hypoxaemia Silent chest Lethargic / confused Status asthmaticus Life threatening (silent chest and a PaCO2 >70mmHg)
Early phase of asthma
Initial allergen response
Symptoms within 10-20 mins
Production of mast cells
Release of chemical mediators from the presensitized mast cells
Causes permeability of mucosa, bronchospasm, mucosal oedema
Late phase of asthma
Develops 4-8hrs after exposure
Inflammation and airway responsiveness
Prolongs asthma attack
Starts cycle of exacerbation
Reaches maximum within a few hours and may last days or weeks
Responsiveness to cholinergic mediators is often increased
Chronic inflammation can cause airway remodelling
Severe phase of asthma
<5% with asthma
Requires high medication use (ICS + controller and/or systemic corticosteroids)
Persistent symptoms despite treatment
Increased risk of near fatal or fatal attacks
Deaths from dysrhythmias and asphyxia due to severe airway obstruction
Underestimattion of severity of attack
Uncontrolled asthma
Poor sx control
Frequent exacerbations
Serious exacerbations (hospital, icu, mechanical ventilation)
Airflow limitation
Controlled asthma that worsens on tapering of corticosteroids
What is a flare up (exacerbation) of asthma
Sx commence or worsen compared to normal
Sx do not spontaneously resolve and require treatment
Rapid onset and can occur over hours or days
What is status asthmaticus
Not reversed by normal measures Hypoxaemia worsens Expiratory flows decrease further Effective ventilation decreases Acidosis develops
Salbutamol
Classification of drug: short acting beta agonist (SABA)
Onset: 10-15 minutes
Peak effect: 30min
Duration of action: 2-6 hrs
Side effects: tachycardia, palpitations, headache, tremor, hyperactivity, hypokalaemia, insomnia
Mild/moderate asthma management
4-12 puffs salbutamol via spacer
Monitor and reassess
Continue every 20-30 mins first hour or sooner if needed
If poor response add IV mag sulf 10mmol over 20mins
Within first hour - start systemic corticosteroids (oral pred or IV hydrocortisone 100mg)
Treatment for severe asthma
Salbutamol 12p via spacer Ipratropium 8p via spacer or Intermittent nebulisation if pt cannot breathe through spacer 5mg salb, 500mcg iprat Give with air unless o2 needed Start O2 if Sats <93% Reassess If poor response - IV mag 10mmol/20min Systemic corticosteroids in first hour Admission/transfer Continue bronchodilator treatment
Treatment for life threatening asthma
2x 5mg nebulised salbutamol add 500mcg ipratropium
Start O2 - titrate >93%
Arrange for transfer - notify senior staff
Consider ventilation- NPPV or intubate
Reassess
Continuous Salbutamol NeBs
IV magnesium 10mmol/20min
Systemic corticosteroids with in first grade
Reassess- discuss with retrieval team/ transfer
