It is 12:05 p.m. in your Resuscitation Bay.

 A 58-year-old man was brought in after collapsing at a wedding dinner shortly after eating shellfish.

 He has a history of hypertension and migraine prophylaxis treated with celiprolol 200 mg once daily.

He has already received in the ED:

Two IM adrenaline 500 µg (1:1000) 5 min apart

3 L Hartmann’s IV fluid

IV hydrocortisone 200 mg + chlorphenamine 10 mg

Adrenaline infusion titrated to 2 mL/kg/h (max rate reached)

Noradrenaline infusion added via central line

Current status (30 min after starting dual infusions):

 He remains pale, cold, confused, with thready pulses.

 HR 56 bpm BP 68/36 mmHg RR 30 SpO₂ 91 % (15 L O₂)

 ABG: pH 7.29 / PaCO₂ 5.1 kPa / Lactate 7.4 mmol/L

 Capillary refill > 5 s despite full resuscitation.

What is the most appropriate next pharmacologic intervention?