Immediate / First Aid
· Keep the victim calm and not let him be anxious
· Immobilise the bitten limb with a splint (movement would increase the absorption of venom into the bloodstream and lymphatics)
· Avoid any interference with the bite wound as this may cause infection, increase absorption of the venom and increase local bleeding
· Consider pressure-immobilisation for bites from snakes of the family Elapidae
1. Pressure Immobilisation Method:
· An elasticated and stretchable bandage (approx 10cm wide and at least 4.5m long) should be used to bind the entire bitten limb starting, lets say bitten upper limb, around the fingers and continue proximally. Include a rigid splint. The bandage must be loose enough to slip a finger between the layers.
Pressure immobilisation is recommended for bites by neurotoxic elapid snakes but not for viper bites because of the danger of increasing local effects of the necrotic venom as this method will increase the intracompartmental pressure. Ideally, such compression bandages should not be released until the patient is under medical care in hospital where resuscitation facilities and antivenom treatment are available.
2. Tight tourniquets
· Not recommended.
· To be effective, the bandage has to be tied very tightly to occlude the peripheral pulse.
· Extremely painful and dangerous as it cause ischaemia.
· Gangrenous limbs resulted.
Proper treatment in Hospital
1. Airway
2. Breathing
3. Circulation
Examples where victims require urgent resuscitation:
· Profound hypotension and shock resulting from direct cardiovascular effects of the venom or secondary effects such hypovolaemia or haemorrhagic shock.
·Terminal respiratory failure from progressive neurotoxic envenoming that has led to paralysis of the respiratory muscles.
· Sudden deterioration or rapid development of severe systemic envenoming following the release of a tight tourniquet or compression bandage.
· Cardiac arrest precipitated by hyperkalaemia resulting from skeletal muscle breakdown (rhabdomyolysis) after the sea snake bite.
· Late results of severe envenoming such as renal failure and septicaemia complicating local necrosis.
Ø History
o Which part of the body is bitten?
o When were you bitten? (there could be no sign and symptom if the patient arrive very soon after the bite)
o Where is the snake that bit you? (if it is a harmless species, there should be no worries)
Ø Look out for bleeding from old, partially-healed wounds as well as bleeding persistently from the fang marks. Happens in patients who become thrombocytopenic (reduce RBC due to lack of platelets).
Ø Ask patient how much urine has been passed since the bite and whether it is a normal colour
Early clues that a patient has severe envenoming:
Snake identified as a very dangerous one
Rapid early extension of local swelling from the site of the bite
Early tender enlargement of local lymph nodes, indicating spread of venom in the lymphatic system
Early systemic symptoms: collapse (hypotension, shock), nausea, vomiting, diarrhoea, severe headache, "heaviness" of the eyelids, inappropriate (pathological) drowsiness or early ptosis/ophthalmoplegia
Early spontaneous systemic bleeding
Passage of dark brown urine
Ø Begin with physical examination
o Observe the extent of swelling (tenderness to palpation)
o Note lymph nodes draining the limb
o Observe the bitten limb ( may be tensely oedematous, cold and immobile)
o Measure the introcompartmental pressure if possible.
o Assess the blood flow and patency of arteries and veins assessed
o Look out for blistering, demarcated darkening or paleness of the skin, loss of sensation and a smell of putrefaction. (early signs of necrosis)
Ø General examination
o Measure the blood pressure and heart rate. (sitting up, lying to detect a postural drop indicative hypovolaemia)
Ø Neurotoxic envenoming
o Where the patient is asked to look up and observe whether the upper-lids retract fully.
o Check other muscles innervated by the cranial nerves (eg. Facial muscles, tongue, gag reflex etc)
Ø Bulbar and respiratory paralysis - A clinical syndrome due to involvement of the nuclei of the last four or five cranial nerves, characterized principally by paralysis or weakness of the muscles which control swallowing, talking, movement of the tongue and lips, and sometimes respiratory paralysis.
o Check if the patient can swallow and sign of bulbar paralysis
o Look out for ‘paradoxical respiration’ – abdomen expands and this indicates that the diaphragm is still contracting but that the intercostal muscles and accessory muscles are paralysed
o A peak flow metre and spirometer can be used to record the max expiratory pressure.
· Generalised rhabdomyolysis
o Look out if muscles (esp in the neck, trunk and proximal part of the limbs) has become tender and painful on active or passive movement.
Antivenom therapy:
Venomous snake bites may be treated with Antivenom. Snake antivenins are a man-made biological product called anti-ophidic serum. Anivenin serum treatment are based on the vaccine process developed by Louis Pasteur, the famous French microbiologist & chemist.
The snake venom is obtained from the snake specimens usually known as ‘milking a snake’
The snake venom is injected in small amounts (non-lethal dose) into mammals such as horses, sheep, or rabbits. These animals have an immune response whereby antibodies against the venom are generated naturally, i.e. the animals are being hyper-immunised. The Antivenom is then harvested from the blood of the animal, purified and stored to treat future envenomation for snake bite victims.
1. Administer antivenom by the intravenous route only. Start slowly, increasing the rate as tolerated. In nonallergic individuals, 5–10 vials of Wyeth antivenom or 4–6 vials of CroFab can be diluted in 250–500 mL saline and given over 60–90 minutes.
2. If there is an inadequate response to the initial dose, give an additional 4 vials of CroFab (5–10 vials of Wyeth) over 60 minutes, or give an additional 6 vials of CroFab if signs of severe envenomation are still present. Repeat in 4- to 6-vial increments (5–10 vials of Wyeth) per hour until the progression of symptoms is halted.
Note:
· It can reverse systemic poisoning even when given hours and even days after the bite.
· Antivenom, however, is generally ineffective in preventing or lessening local effects of snake venom poisoning.
· Monospecific (monovalent) antivenoms are more effective and less likely to cause reactions than polyspecific (polyvalent) antivenoms. At present, however, monospecific antivenoms are available only against the three common types of Malaysian poisonous snakes (anti-Malayan pit viper, anti-Malayan cobra and anti-Enhydrina schistosa).
· Some commercially available polyvalent antivenoms (in particular, polyvalent Trimeresurus antivenom and polyvalent Elapid antivenom from National Institite of Preventive Medicine, Taiwan, R.O.C.) may be useful for the treatment of snake venom poisoning caused by other Malaysian poisonous snakes. However, these have not been evaluated clinically.
Early (anaphylactic), pyrogenic and late (serum sickness) reactions can occur after antivenom treatment. Reported incidence of early reactions following intravenous antivenom ranges from 3 to 5%.
About 40% of these reactions involve severe systemic anaphylaxis (bronchospasm, hypotension or angioneurotic oedema), though few fatal cases have been reported. Most authorities have recommended that antivenom should be diluted in isotonic fluid and given by slow intravenous infusion.
Alternative treatment
Cold-pack method:
· Apply a cold compress directly over the wound after the bitten site is cleaned.
· The main action theme is quick application of ice or very cold pack, followed by safe transport to a valid medical facility.
· The tremendous burning associated with venom seems to be alleviated through the use of a cold compress.
· It is important to periodically change surface areas with the cold pack for this reason. The cooler body temperature in the local bite area will have somewhat reduced circulation and spread of venom, and further, that swelling seen as the worst symptom to deal with may be checked or reduced during transport time.
Electricshock Method
· DC current is used.
· The idea is to hit the area with enough voltage to damage the cellular molecules of the venom. This must be accomplished at the same time that low enough amps are used to prevent tissue burning, organ damage, convulsions, and a host of other possibilities being experienced from uncontrolled voltage.
Traditional medicine:
Many plants are used traditionally as active agents against various effects of snake venoms. A total of 578 species of higher plants from 94 families have been cited in literature as the active agents. However, few attempts have been made to correlate them scientifically with anti-snake venom properties. One of potential natural remedies is the mimosa pudica which showed 100% ability in neutralising the lethality of naja naja kaouthia venom. It also showed 50% or more ability in fighting against Ophiophagus Hannah, Bungarus candidus and calloselasma rhodostoma venoms.
http://info.frim.gov.my/cfdocs/infocenter/Korporat/2003Publications/Links/JTFS%2019(4)/01%20J.%20Vejayan.pdf
www.searo.who.int
http://www.tigerhomes.org/animal/snake-antivenom.cfm
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