asthma

• Characterised by episodes of dyspnoea, cough, wheeze
• Reversible airway obstruction and bronchospasm
• Inflammatory disorder reduces air flow rate

Causes/Factors

Exact cause of asthma still unknown but autoimmune/mast cell basophil degranulation

• Triggers: cold air, exercise, emotion, allergens, infection, smoking, pollution, NSAIDs/$\beta$ blockers (for some)
• Worse in the morning - this can be severe enough to tip the balance into an attack
• Acid reflux - 40-60% of those with asthma have acid reflux
• Other autoimmuney diseases - exzema, hay fever, allergies/family history
• Work/job related - gets worse on weekdays and better on weekends/holidays

Symptoms

• Nocturnal cough
• Wheeze
• Worsening of eczema

Signs

• Tachypnoea
• Hyperinflated chest
• Hyper-resonant percussion
• decreased air entry
• accessory muscle use

Diagnostic Tests

• Sputum culture
• ABG: $\downarrow Pa{O}_2$ but also $\downarrow PaC{O}_2$ (hyperventilation)- **if $\uparrow PaC{O}_2$ failing respiratory
• Spirometry: decreased $FE{V}_1/FVC$ ratio
• Bronchodilator reversibility testing: An increase in the $FE{V}_1$ of 12% or more after inhalation of a short-acting bronchodilator is indicative of asthma
• Peak flow - less than predicated or best

Moderate	Severe	Life-threatening
PEFR 50-75% best or predicted Speech normal RR < 25 / min Pulse < 110 bpm	PEFR 33 - 50% best or predicted Can’t complete sentences RR > 25/min Pulse > 110 bpm	PEFR < 33% best or predicted Oxygen sats < 92% Silent chest, cyanosis or feeble respiratory effort Bradycardia, dysrhythmia or hypotension Exhaustion, confusion or coma

Management

Step	Notes
1 Newly-diagnosed Asthma	Short-acting beta agonist (SABA)
2 Not controlled on previous step OR Newly-diagnosed Asthma with symptoms >= 3 / week or night-time waking	SABA + low-dose inhaled corticosteroid (ICS)
3	SABA + low-dose ICS + leukotriene receptor antagonist (LTRA)
4	SABA + low-dose ICS + long-acting beta agonist (LABA) Continue LTRA depending on patient’s response to LTRA
5	SABA +/- LTRA Switch ICS/LABA for a maintenance and reliever therapy (MART), that includes a low-dose ICS
6	SABA +/- LTRA + medium-dose ICS MART OR consider changing back to a fixed-dose of a moderate-dose ICS and a separate LABA
7	SABA +/- LTRA + one of the following options: - increase ICS to high-dose (only as part of a fixed-dose regime, not as a MART) - a trial of an additional drug (for example, a long-acting muscarinic receptor antagonist or theophylline) - seeking advice from a healthcare professional with expertise in Asthma

Maintenance and reliever therapy (MART)

• a form of combined ICS and LABA treatment in which a single inhaler, containing both ICS and a fast-acting LABA, is used for both daily maintenance therapy and the relief of symptoms as required
• MART is only available for ICS and LABA combinations in which the LABA has a fast-acting component (for example, formoterol)

Acute exacerbations - see acute management Oh
Shit,
I
Hate
My
Asthma

1. Oxygen
2. Salbutamol nebulisers
3. Ipratropium Bromide nebulisers
4. Hydrocortisone IV or Oral Prednisolone
5. Magnesium Sulfate IV
6. Aminophylline / IV Salbutamol

Complications/red Flags

• Silent Chest
• Confusion
• Bradycardia

Warning

Prior to discharge, following an acute Asthma attack, a patient should have been stable on their discharge medication (i.e. no nebulisers or Oxygen) for 12-24 hours, PEFR >75% of expected and have had their inhaler technique checked and recorded

DDX

• pulmonary oedema, COPD, airway obstruction, pneumothorax, pulmonary embolism, bronchiectasis