Suspect anaphylaxis if there is:
Rapid development of stridor and/or wheeze and/or hypotenison assoiated with itch, skin and mucosal angioedema and urticaria following exposure to potential trigger (see Table 38.2 for causes)

End

Post reaction care
Observe for biphasic reaction
If drug implicated mark notes, drug charts and issue patient with 'alert' wrist band
Continue oral steroids prednisolone 30–40 mg daily for 3 days (longer course if asthma) and antihistamines – cetirizine 10 mg daily or chlorphenamine 4 mg tds

Pre-discharge care
Assess risk of further anaphylaxis and requirements of adrenaline autoinjector
Advise on future allergen avoidance
Refer for specialist investigation

Remove allergen if possible¹
Lay patient flat with legs elevated²
Call for additional help

Administer IM adrenaline – anterolateral aspect of thigh using 25 mm needle: 500 µgm (0.5 mL 1:1000 solution).
Further doses at 5– 10 min intervals if no improvement

1. Stop any infusions including colloids. Vomiting should NOT be induced when allergens have been ingested.

2. Lying flat increases respiratory effort and should not be forced in patients in whom ariway problems predominate.

3. If there is hypotension, give 1 L normal saline or Hartmann's solution IV over 10 mins. If normotensive, give 500 mL; if heart failure, give 250 mL and monitor for signs of fluid overload. Consider CVP monitoring.

4. Myocardial ischaemia may occur even with unobstructed coronary arteries

Insert large bore cannula
High flow O₂

Airway/breathing
For wheeze nebulized salbutamol 2.5– 5 mg; treat asthma as per BTS guidelines. (Figure 60.1 p. 378)
Upper airways obstruction may require endotracheal intubation or tracheostomy

Circulation
Give IV fluid challenge over 10 min³
Repeat challenge if BP remains < 100 mmHg; if no improvement seek specialist supervision of IV adrenaline and other vasopressors

Monitor:

BP
ECG⁴
Pulse oximetry

Give second line drugs:

Chlorphenamine 10 mg slow
IV push
Hydrocortisone 200 mg IV

Check serum tryptase (see Table 38.4)