Is it an Emergency?

Inquire

• time of the bite,
• local pain,
• nausea, vomiting, abdominal pain.

Assess

• state of consciousness.

Measure

• blood pressure/pulse,
• respiratory rate,
• oxygen saturation (pulse oximeter),
• 20WBCT (bedside test), in settings where resources are immediatelly accessible, go directly to 'Laboratory and physical investigations' below,

Observe/investigate

• bite marks,
• extent and intensity of local swelling,
• enlargement and painfulness of regional lymph nodes,
• swelling in the facial region, including the larynx/pharynx (angio-oedema),
• conjunctival oedema,
• clinical signs of a pleural effusion, pulmonary oedema,
• clinical signs of shock,
• bleeding in the region of the swelling,
• bleeding from bite marks and other injuries,
• gingival bleeding,
• blood-stained sputum, vomit ("coffee ground vomitus"), stools (melaena) or urine,
• acute abdomen (intra-abdominal bleeding!),
• focal neurological deficits, meningismus (intracranial bleeding!),
• cranial nerve deficits, such as ptosis, ophthalmoplegia, dysphagia, dysarthria,
• paralysis of the skeletal musculature including the respiratory musculature (→ respiratory insufficiency/respiratory failure),
• myalgia with active and passive movement and upon pressure,
• dark-brown/red urine (differential diagnosis haemoglobinuria)(rhabdomyolysis!),
• flank pain and renal bed sensitive to percussion,

Varibility of symptoms and degree of envenoming

The symptoms and degree of envenoming depend not only on the amount of venom injected and numerous other variables, but also on the time that has elapsed since the bite. This variable factor must be taken into account when making the following decisions:

• exclusion of envenoming 
• the time interval between clinical examinations
• emergency care (see below) 

The following signs and symptoms are observed following European viper bites and are indicative of a relevant injection of venom: 

• local pain, swelling and skin changes (in particular ecchymoses),
• nausea, vomiting, diarrhoea, abdominal pain,
• arterial hypotension,
• signs of shock (pallor, sweating, tachycardia, arterial hypotension, alterations in consciousness).
• neurological signs and symptoms, in particular cranial nerve deficits (rare and only in certain geographical areas). 

Cardiovascular collapse / arterial hypotension, schock (autopharmacological effects)

One of the major complications following bites from European vipers is a state of acute transient, persistent or recurrent arterial hypotension. Arterial hypotension combined with other signs of an allergic/anaphylactic reaction, such as urticaria, angio-oedema and bronchospasm, generally commence directly following the bite, can, however, be delayed for several hours (Warrell 2005, 2010).

This applies to autopharmacological but also to allergic, IgE-mediated reactions which also can be delayed or biphasic (Stark and Sullivan 1986)

It most often happens pre-hospital and immeditae life support is essential.

Local signs & symptoms

The oedema can take on immense proportions and involve large areas of the trunk, such that it may be a cause of hypovolaemia and arterial hypotension.
Permanent tissue damage is almost always the result of inappropriate first aid and paramedical measures.

Non-clottable blood and bleeding

Systemic bleeding is extremely rare. Significant changes in the haemostatic parameters with or without clinical manifestations are an exception even in cases of severe envenoming.

Descending paralysis / Respiratory failure

Cases of V. aspis bites with signs and symptoms of neurotoxicity have been described for Italy (Antonini et al. 1991, Beer and Putorti 1998, Re et al 1999) and South-Eastern France (de Haro et al 1994, 2002). Mild neurotoxicity has also been described after bites of other European vipers (Warrell 2010).

Myocardial injury

Myocardial damage in association with bites by European vipers has been reported but is extremely rare.

Acute kidney injury (AKI)

Clinically relevant renal dysfunction is rare. If it occurs, it is probably (always) secondary, i.e. primarily a consequence of arterial hypotension.

Patients for whom the initial examination provided no indication for antivenom administration

At least hourly

• state of consciousness,
• heart rate and rhythm,
• arterial blood pressure,
• respiratory rate,
• spontaneous bleeding,
• ptosis,
• local swelling,
• other newly appearing signs and symptoms.

6-hourly (or more frequently if there is cause for suspicion)

• 20WBCT (bedside test), in settings where resources are immediatelly accessible, go directly to 'Laboratory and physical investigations' below,
• urine output.

A complicated course of envenoming requiring antivenom treatment can be excluded if within a 24-hour observation period

• the oedema ceases to increase in extent,
• neither hypotension nor shock have occurred,
• haemostasis is unimpaired,
• there are no cardiac symptoms and no ECG change