Is it an Emergency?

Inquire

• time of the bite,
• nausea, vomiting, abdominal pain.
• Bite
  • Local pain,
  • local redness, 
  • local swelling
  • necrotic soft issue

• Urticating hairs
  • Skin
    • irritation and rashes; itching of the skin that can persist for several months 
  • Eyes
    • irritation and redness.

Assess

• state of consciousness.

Measure

• blood pressure/pulse,
• breathing (respiratory rate),
• oxygen saturation (pulse oximeter).

Observe/investigate

• Bite
  • Local pain,
  • local redness, 
  • local swelling
  • necrotic soft issue
• Urticating hairs
  • Skin
    • urticaria, papular dermatitis; itching of the skin can persist for several months 
  • Eyes
    • Keratitis, conjunctivitis, iritis, chorioretinal scar
• Cholinergic effects
  • Vomiting; sweating; hypersalivation and hyperlacrimation.
  • Bradycardia, arterial hypotension, shock. 
  • Priapism.
• Adrenergic effects 
  • Tachycardia, arterial hypertension, myocardial failure, pulmonary oedema (cardiogenic + ?non-cardiogenic component), cardiac ischaemia, shock, arrhythmias.
• Neuromuscular dysfunction
  • Muscle fasciculations and spasms, local and generalised

• Record and measure
  
  • ECG,
  • Blood sugar,
  • Clotting / bleeding
  • Symptoms and signs of haemolysis

Loxosceles sp.
Severe envenoming with necrosis (very rare) and time course of the development of the lesion
"The bite may be painless initially, but there is progressive local discomfort over the next 2-24 hours. Stinging or burning pain develops with local erythema, itching and indurated swelling. Between 12-72 hours post-bite, a painful, tender ischaemic lesion appears, the ‘red-white-and-blue’ sign, its outer ring coloured red (vasodilatation), white (vasoconstriction) and central blue (pre-necrotic cyanosis) with serous or haemorrhagic vesicles, or blisters. It may spread gravitationally. Over the next 3-7 days, a black necrotic eschar develops in 60% of cases, which sloughs in a few weeks, sometimes leaving a deep necrotic ulcer.” (Warrell 2023; see also Sams et al 2001a; Table IV Typical evolution of Loxosceles lesion)).

Cutaneous-haemolytic loxoscelism (rare)
Haemolysis appears to occur rapidly or with a long delay after the bite (24–72 h to 2–3 days) (de Souza et al 2008; DiPaola et al 2022; Futrell 1992; Laxton et al 2024; Lucas 1988; Wasserman and Anderson 1983–84; Rosen et al 2012). Acute renal failure (AKI) is less frequent and is associated with poor outcomes (Isbister and Fan 2011). AKI is infrequent and only occurred in cases manifesting massive haemolysis (de Souza et al 2008; Malaque et al 2011).

Symptomatic emergency medical treatment and antivenom treatment are complementary strategies.

Antivenom in those spider bites in which antivenom is avaibale, of proven value and indicated, it must be secured as early as possible while emergency medical treatment is running.

The aim of symptomatic emergency medical treatment is the rapid correction of critical parameters (fluid balance, blood pressure, oxygenation etc.) and the maintenance of vital functions (respiratory, cardiovascular).

Symptomatic measures help bridge the gap until specific treatment (antivenom) can be administered and starts being effective. If no antivenom is available or if the required effect is not achieved with antivenom, the goal is to employ symptomatic measures until such time as the venom naturally starts losing its activity.

The aim of antivenom treatment is neutralisation of the venom. The success of antivenom treatment depends on the quality of the antivenom, the specific properties of those venom components relevant to envenoming and the time point at which antivenom is administered (neurotoxic envenoming).