Snakebite Treatment Protocol Swaziland Antivenom Foundation 1. Detailed Clinical Assessment and Species Diagnosis 1.1. History A precise history of the time and circumstance of the bite and the progression of local and systemic symptoms and signs is of the utmost importance. Five initial questions should be asked i. “In which part of your body have you been bitten?” Look where the patient points. There may be evidence that the patient has been bitten by a snake (for example: fang marks), with signs of local envenoming (for example: local swelling, bruising or continuing bleeding from the fang punctures), but also evidence of pre-hospital treatment (for example: impressions made by a tourniquet or incision marks that may be bleeding, suggesting that the blood is incoagulable). The snakebite may not have been recognized by the victim, if it occurs at night during sleep, or in the dark, or in water. In such cases, suspicion of the diagnosis will depend on typical signs such as fang puncture marks, progressive swelling, bleeding gums or descending paralysis. ii. “What time were you bitten?” Assessment of the severity of envenoming depends on the length of time between the actual bite and when the patient seeks treatment. The patient seeks treatment so soon after the bite that symptoms and signs of envenoming have not yet developed. Or, the patient may arrive so late after the bite that the only signs are of late complications of envenoming (for example: gangrene, pneumonia or renal failure). iii. “Where is the snake that bit you?” or “What did the snake look like?” The snake responsible for a bite may be killed and brought to hospital with the victim. If the snake is available, its identification can be extremely helpful but only if there is someone competent who can identify the snake (for assistance contact Thea 76025088 ). If it is obviously a harmless species (or not a snake at all), the patient can be quickly reassured, given an injection of tetanus toxoid and discharged from hospital immediately. Descriptions of the snake by bite victims or onlookers are often unreliable and misleading but it is worth asking about the snake’s size, colouring, markings and behaviour. The surroundings where the bite occurred and the time when it happened can also suggest a particular species: • Cobras may rear up and spread a characteristic hood and hiss; puff adders make a loud blowing sound • Dangerous tree snakes include Black mamba, Boomslang and Vine snake. • Any green tree snake longer than about 1 m is likely to be a Boomslang (juvenile Boomslang are not green). All snakes that are green and shorter than 80cm are totally harmless. • Bites inflicted on sleeping persons in their huts at night are likely to have been caused by Mozambique spitting cobras • Bites in and near rivers, lakes and marshy areas are also most likely to be caused by Mozambique spitting cobras. • Bites at night are generally caused by Puff adders, Mozambique spitting cobras or Night adders iv. “How are you feeling now?” The patient’s current symptoms can point to what is likely to be the most important effect of envenoming (for example: faintness or dizziness indicating hypotension or shock; breathlessness indicating incipient respiratory failure). Do not ask leading questions! Patients should be asked to describe their symptoms and should then be questioned directly about the extent of local pain, swelling, tenderness, tender painful enlarged lymph nodes draining the bite area, bleeding from the bite wounds, at sites of other recent injuries and at sites distant from the bite (gums, nose etc), motor and sensory symptoms, vomiting, fainting and abdominal pain. The time after the bite when these symptoms appeared and their progression should be noted. Details of pre-hospital treatment (tourniquets, ingested and applied herbal remedies etc) should also be recorded as these may, themselves, be responsible for some of the symptoms. v. “Have you ever been bitten before and did you receive antivenom?” If the patient has been bitten before he/she may have an allergic reaction to the VENOM. Snake handlers will very often have a severe reaction to the venom. This must not be confused with anaphylaxis as urgent and large quantities of AV will be required. If the patient has received antivenom before, there is an increased risk of anaphylaxis. 1 | Eswatini Antivenom Foundation - This document may not be copied or distributed in any way . Amended: April 2019 2. Examination A. Immediately and clearly draw a ring around the bite site with a permanent marker and record the time B. The patient should be monitored every 30 - 60 minutes. Record the symptoms as well as the progress of swelling and the time. Figure 1: Record progress of swelling every 30 minutes. 2.1. Tooth and Fang marks The absence of visible fang marks does not exclude snakebite. Often, with the Black mamba, there is no evidence of a distinct puncture wound and a tiny scratch from a Boomslang is enough to cause a serious reaction as the venom is extremely potent. There may be slight bruising or the puncture wound may resemble a pimple. Two or more distinct, separate puncture marks suggests a bite by a venomous snake. The pattern of fang punctures is very rarely helpful as marks made by accessory fangs, palatine maxillary and mandibular teeth may complicate the pattern and there may have been multiple bites and scratches. The greater the distance between the fang marks, the larger the snake. All© Thea Litschka-Koen Figure 2 (left): Simunye, Swaziland. A typical bite from a non -venomous snake Figure 3 (second from left): Big bend, Swaziland. Two clear fang marks by a venomous snake with blistering 3 hours after envenomation Figure 4 (third from left): Siteki, Swaziland. Severe envenomation by a Black mamba. No clear fang mark, only slight bruising Figure 5 (second from right) : Siteki Swaziland. Severe envenomation by a black mamba the bite site only showing a tiny spot with no bruising Figure 6 (second from right): Nelspruit, South Africa. Severe envenomation by a Boomslang. 2.2. Local Signs Local swelling and enlargement and tenderness of regional lymph nodes are often the earliest signs of envenoming, but swelling may be caused or aggravated by a venous tourniquet or traditional remedies. Local swelling, caused by cytotoxic snakes, like the adders and spitting cobras, are usually visible within two hours of the bite, but there have been exceptions to this rule. Symptoms and signs of severe systemic envenoming from the two Haemotoxic snakes (Boomslang and Vine snakes) can be delayed for 15 hours or more. Most often there will be negligible local swelling. With neurotoxic envenomation by the Black mamba and snouted cobra, there will be little or no swelling. All© Thea Litschka-Koen Figure 8 (left): Siteki, Swaziland. Mozambique spitting cobra 2 hours after envenomation. S welling, typical bruised area, no bleeding from bite site. Figure 9 (second from left): Simunye, Swaziland. Mozambique spitting cobra 6 hours after envenomation. Typical bruised area “dam” with blisters forming around the discoloured area. Figure 10 (centre): Mhlume, Swaziland. Puff adder bite 5 hours after envenomation. Typical random blistering with bleeding from the blisters and bite site. Figure 11 (second from right) : Siteki Swaziland. Black mamba bite. Swelling was caused by tourniquet and self inflicted wounds. Figure 12 (right): Big Bend, Swaziland. A non-venomous bite but severe swelling caused by self inflicted cuts and herbal potion rubbed into the wounds. 2 | Eswatini Antivenom Foundation - This document may not be copied or distributed in any way . Amended: April 2019 2.3. Bleeding Persistent bleeding from the fang marks, other recent wounds and venepuncture sites suggest that the blood is in-coagulable (Haemotoxic envenomation by the Boomslang or Vine snake). The gums should be examined thoroughly as these are usually the first sites of spontaneous systemic bleeding. ©David Dr. Warrell ©David Dr. Warrell Figure 13 (left): Haemotoxic envenomation showi ng bleeding of the gums. Figure 14 (second from left): Haemotoxic envenomation. 2.4. Shock The signs of shock are blurred vision, dizziness, fall in blood pressure; collapse; cold, cyanosed and sweaty skin; and impaired consciousness, sometimes occurring very soon after the bite; these symptoms may be transient, recurrent, persistent, progressive, delayed and life threatening. The foot of the bed should be raised and an intravenous infusion of isotonic saline or a plasma expander such as haemaccel, gelofuse, dextran or fresh frozen plasma should be started immediately. 2.5. Neurotoxicity/paralysis The earliest symptoms of neurotoxicity after bites from the Black mamba or Snouted cobra are often a metallic taste, paresthesia of the lips (black mamba bite), blurred vision, a feeling of heaviness of the eyelids and drowsiness. The victim will raise the eyebrows and pucker the forehead before ptosis is observed. Respiratory muscle paralysis with imminent respiratory failure is suggested by dyspnoea, distress, restlessness, sweating, exaggerated abdominal respiration and cyanosis. Coma is usually the result of respiratory or circulatory failure. 2.6. Monitoring of snake-bitten patients Patients bitten by snakes should, ideally, be observed in hospital for at least 24 hours after the bite. The intensive care unit or a high dependency bed is appropriate but rarely possible. In an open ward, the patient should be placed close to the nursing station and in full view of the medical staff. The following should be checked at least once every hour and action taken if there is any deterioration: i. Level of consciousness. ii. Metallic taste, llight-headedness, dizziness, bitter taste in mouth, paraesthesiae of the tongue, lips and mouth , headache, dull pain in the abdomen, severe thirst and dry mouth, increased / severe sweating, weak limbs and poor co-ordination, nausea and vomiting, fasciculation’s , gooseflesh , increased salivation , difficulty to cough, dysphasia, hoarseness, ataxia, nosebleed, flushed face, warm / cold skin, shock, hypotension, dysphagia, ptosis.