First aid for Funnel-web Spider bites - why and how
Despite the availability of an effective antivenom, correct and immediate first aid is still an essential requirement for funnel-web spider (and mouse spider) envenomation. The recommended first aid technique is pressure/immobilisation (as for snake bite) and this must be done as quickly as possible.
To be transported to susceptible tissues and organs, venom injected by the fangs into the sub-surface tissue fluid space must first get into the blood stream. It does this via the lymphatic system, a tenuous network of drainage vessels whose valves allow fluid to travel forward only, propelled by the intermittent squashing effect of muscle movement. The vessels progressively coalesce and eventually empty into the bloodstream. Because the toxic funnel-web venom molecules are quite small, they can pass relatively quickly through the lymphatics.
The main job of first aid is to prevent this from happening. The pressure/immobilisation technique (as for snake bite) does this by compressing surface tissues and reducing muscle movement, so greatly slowing the lymphatic flow.
Spider bites usually take place on a limb. A pressure bandage should be applied as soon as possible after a bite has occurred. This should be applied as tightly as for a sprained ankle, starting from the bitten area and binding the entire limb above the bite. A rigid splint should be bound onto the limb to prevent limb movement. The patient should be kept as quiet as possible and medical attention sought. If possible, keep the spider for positive identification.
