If a tourniquet has been applied, it should not be removed until antivenom is at hand or has been administered and the means for treating complications, including possible complications caused by the antivenom, are available. If these requirements cannot be met within a suitable period of time, it is necessary to weigh the risk of the systemic effects of the venom that could occur after removing the tourniquet against the risk of progressive local tissue damage that may arise if the bandage is left in place.

Respiratory arrest within minutes of removing a tourniquet has been described, even in patients who were asymptomatic before the tourniquet was removed (N. philippinensis; Watt et al. 1988b).

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 (see below),
• the time interval between clinical examinations (see Therapy phase: Hospital),
• emergency care (see below).

The fact that a patient has been bitten by a known venomous snake and the presence of bite marks do not automatically allow the conclusion that a clinically relevant injection of venom has taken place. Approximately 50% of confirmed Cobra bites in Malaysia and Thailand proceed with no detectable symptoms or at the most negligible local signs of envenoming (Reid 1964, Viravan et al. 1986).

Local signs, e.g. swelling at the site of the bite, following viperid and crotalid bites, as well as bites of some Cobra species, are an indication that a significant injection of venom has occurred. With Kraits, however, there are no local signs at all, and they are also unreliable following D. russelli bites.

Krait bites in particular may be completely unnoticed and unrecognised initially, as these snakes often bite humans at night while they are asleep. A Krait bite is thus an important differential diagnosis of signs of paralysis (of the cranial nerves, extremities, respiratory musculature).

Abdominal pain is recognized as a characteristic symptom of some kraits, in particular B.caeruleus (Ariaratnam et al 2008).

Clinically evident signs of a haemostatic defect may be absent. Nonetheless defibrin(ogen)ation may be present to such a degree that the blood is completely incoagulable. For this reason the simple clotting time test should always be performed if a viperid or crotalid bite is suspected.

To date, acute pituitary/adrenal insufficiency has only been reported in Myanmar, southern India and Sri Lanka. It is a complication of D. russelii siamensis and D. russelli russelli (pituitary) and D. russelii pulchella bites (adrenal) and generally does not occur during the acute phase of severe envenoming, but shortly thereafter. A simple rapid diagnostic test for blood sugar and observation of the patient's treatment-resistant hypotensive condition aid in the differential diagnosis (see the Biomedical database entry for D. russelii).

The absence of signs of envenoming in the first hours after the bite does not exclude the possibility that a relevant injection of venom has taken place. There can be a long delay before systemic signs of envenoming develop.

Symptomatic emergency medical treatment and antivenom treatment are complementary strategies.

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.

• Treatment of the haemorrhagic shock,
• antivenom.

Symptomatic emergency medical treatment and antivenom treatment are complementary strategies.

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.

• Cleaning, disinfection and dressing of the wound at regular intervals.
  
• Immobilisation of the extremity with a splint.
  
• Padding and monitoring to prevent pressure necrosis and disturbance of the blood circulation if the oedema increases.
  
• Possibly also prophylactic antibiotic treatment:
  
  • no interference with the bite wound: penicillin or erythromycin,
  • bite wound has been interfered with (incisions etc.): penicillin or erythromycin + aminoglycoside (Warrell 1990b).

• Irrigation with water.
• Corneal lesions: local antibiotic (tetracycline, chloramphenicol) for the prevention of secondary infections and covering the eye. If a corneal lesion cannot be diagnosed because the necessary instruments are not available, the eye should be treated as if a corneal lesion were present (Warrell 1990b).