Anaphylaxis and asthma

Question 1

What features define anaphylaxis?

Answer 1

1. Sudden onset and rapid progression of symptoms from a hypersensitivity reaction
2. Problems with either A B or C (or all)
   2a - Airway problems = swelling of throat and tongue –> stridor
   2b - Breathing problems = wheeze, dyspnoea
   2c - Circulation problems = hypotension, tachycardia
3. Also likely to see generalised pruritus and erythematous / urticarial rash

Question 2

How should you manage anaphylaxis?

Answer 2

-IM ADRENALINE 0.5ML 1 IN 1000 (500 micrograms)
–Can be repeated every 5 mins if necessary
-If in refractory anaphylaxis ie persisting problems after 2 doses –> IV fluids for shock and ICU referral for IV adrenaline infusion

Question 3

How should you manage anaphylaxis following stabilisation?

Answer 3

-Non-sedating oral antihistamines
-Serum tryptase levels to confirm anaphylaxis
-Specialist allergy clinic referral
-Beware biphasic reactions occur in 20% (cautious discharge)

Question 4

How are different severities of asthma exacerbation classified?

Answer 4

MODERATE = 50-75% of best PEFR
-Normal speech
-RR <25
-HR <110
SEVERE = 33-50% of best PEFR
-Can’t complete sentences
-RR >25
-HR >110
LIFE-THREATENING = <33% of best PEFR
-Exhaustion, confusion
-Silent chest, cyanosis
-HR <60
-‘Normal’ pCO2
NEAR-FATAL
-As above but high pCO2

Question 5

How should a severe/life-threatening asthma attack be managed?

Answer 5

OXYGEN
-15L NRBM and titrate down
BRONCHODILATION
-High-dose inhaled salbutamol via nebs
CORTICOSTEROID
-40-50mg prednisolone PO
IPRATROPIUM BROMIDE
-If no response or life-threatening attack
-Given via nebs
IV MAGNESIUM SULPHATE

Question 6

When can you safely discharge a patient following an asthma attack?

Answer 6

-Been stable on discharge meds for 12-24 hours
-Inhaler technique checked and recorded
-PEFR >75% best