If there is either a sudden fall in blood pressure or bronchospasm after starting the antivenom infusion, then temporarily stop the antivenom and give adrenaline, either by infusion pump or by subcutaneous injection, give 100% O2 and IV fluids (Haemaccel®).
If there is an infusion pump set up, then commence cautious IV infusion of 6 mg/100mL adrenaline dilution (at about 10mL/hr), increasing the rate if there is no response in a few minutes, and decreasing the rate as soon as a sufficient response is obtained. Once the untoward antivenom reaction is thus controlled, cautiously recommence antivenom infusion.
If adrenaline is to be given by subcutaneous injection, use a
1:1000 solution. For adults give 0.5mL (0.5mg) initially. For
children give 0.01mg/kg initially. Repeat as necessary and try IM
injection if no response to SC injection (beware potential for major
muscle haematoma with IM injection and venom induced coagulopathy).
If bronchospasm is the major problem, try nebulised adrenaline, 2mL
of 1:1000 solution.