Funnel web spiders

Pressure-immobilisation is the recommended first aid for funnel web spider bites. The use of adrenaline is NOT recommended. An antivenom is available and should be administered as soon as possible. It is rare for an individual to have an allergic reaction to the antivenom, but patients should be closely monitored for signs at all times.

First Aid If no first aid has been applied prior to the patient reaching hospital, this should be applied on arrival. It should remain in place until the antivenom is available, monitoring is in place and expertise and equipment for resuscitation and mechanical ventilation are assembled. This should preferably occur in an intensive care unit. Intravenous access should be secured as soon as possible, as the patient may become confused and difficult to manage. If no symptoms or signs have developed four hours after the bite, or after the removal of first aid measures, the patient may be discharged. The majority of patients presenting to hospital have not been envenomed.

Antivenom use The use of adrenaline as a premedication is NOT recommended in this situation because the venom causes widespread catecholamine release. The initial dose of antivenom is 2 ampoules, which should be administered intravenously, initially very slowly whilst observing for evidence of an allergic reaction. If no reaction occurs, the rate of administration may be increased. Another ampoule should be given if no improvement is observed after 15 minutes, and further doses given at similar intervals until the patient's condition improves. No adverse reactions have been reported after treatment with funnel web spider antivenom, which consists of highly purified rabbit IgG. Supportive treatment may include oxygen, nasogastric aspiration (acute gastric dilatation has been described), atropine (for excessive salivation), antihypertensives, sedation +/- muscle relaxants to facilitate ventilation, positive pressure (hyper)ventilation +/- PEEP and invasive monitoring.

Envenomation by the Northern-Tree Dwelling-Funnel Web Spider (Hadronyche formidabilis) Although experience of envenomation by this spider is limited, it appears that the above treatment, including the use of Atrax robustus antivenom, helps slow or stop the envenomation process. It probably works for other funnel web spider bites, too.