Snake-bite is a medical emergency. SNAKE BITE TREATMENT PROTOCOL involves the decision whether to administer the ASV as anti snake-venom (ASV) is the only antidote that is recognized as potentially lifesaving in such a situation.
SNAKE BITE TREATMENT PROTOCOL
- ABC. Ensure the Airway is patent, the patient is breathing normally and circulation is intact , the patient is having a good volume pulse.
- Assess the patient after obtaining a proper history. Perform a head to toe examination to look for bite marks (that may not be evident or hidden)
- Look for signs of shock which include shortness of breath, hypotension, tachycardia, confusion
- Hydration should be well maintained. IV fluids and colloids should be used to avoid hypotension or hypo perfusion and ensuing renal failure.
- In severe cases inotropic support and vasopressors can be used to treat shock.
- Complete blood counts, coagulation profile and basic metabolic panel including renal function tests, liver function tests and blood sugar should be done
- Cross matching for blood and arrangement of blood products like fresh frozen plasma should be ensured.
- Remember , Hemoglobin levels in cases of acute blood loss are unreliable so blood transfusion should not be withheld in case of active bleeding with clinically evident anemia just on the basis of a normal hemoglobin level.
- Petechiae and pupura over the skin should be looked for
- Any evidence of bleeding from the nose, gums, urine (hematuria), GIT (Hematemesis, melena, lower GI fresh bleed) should be looked for.
- Based on the condition of the wound, antibiotic prophylaxis should be considered.
- Tetanus prophylaxis booster shot should be given
Anti Snake Venom (ASV):
ASV is the most important and life saving component of Snake-bite treatment and management. Anti venoms are basically immune globulins obtained from hyper immunized horses. The dose of the ASV is decided according to the size of the envenomation thus the doses of ASV remain the same in both adults and children.
ASV should be administered if there are obvious neurological deficits, positive 20 minute whole blood coagulation test in which the blood does not coagulate or there is systemic bleeding actively.
What is the 20 minute whole blood coagulation test as part of SNAKE BITE TREATMENT PROTOCOL ?
Take 3 ml of blood of the patient with snake bite in a sterile dry glass tube or syringe and place it at 45° for 20-minutes. See for development of a blood clot. Based on whether the blood clots or not , ASV administration is determined further.
If the patient has no neurological signs then we perform the 20 minute WBCT Test. If the blood coagulates during this period of 20 minutes then there is no need for ASV and one can reassure the patient. The patient can be observed for a period of 24 hours with a repeat test after this duration just to be sure.
If the blood does not clot and the culprit behind the snake bite is a known Viper snake then 4 Vials of ASV are given in 500 ml N/S as a stat dose over one hour. The 20 WBCT test is repeated after 6 hours. If the blood still doesn’t coagulate then add 1 more vial i.e give 5 vials of ASV in 500 normal saline as compared to the initial 4 given. If it does coagulate then one can observe the patient for a further 12 hours and repeat the test thereafter.
For all other snake bites other than that of viper snake 8-10 Vials of ASV in 500 ml N/S over one hour is given with the same protocol of repeating the 20 minute test after 6 hours. If coagulated blood is there then there is simple observation of the patients. However, if the blood isn’t coagulated despite this initial dose then the same dose with addition of one more vial of ASV is repeated every 6 hours till the blood gets coagulated.
If upon initial presentation , neurological signs are present then ASV is given and patient is reviewed within an hour. The ASV is given regardless of the fact whether there is any bleeding diathesis or not. If the signs persist then ASV dose is repeated plus anticholinesterase drugs are tried. Atropine , neostigmine can be utilized for this purpose. If there is no improvement despite anticholinesterase medication then this is not a good sign and indicates an impending ventilatory failure requiring urgent ICU referral for mechanical ventilation.
ASV administration is associated with type I and type III hypersensitivity reactions. If an allergic reaction is suspected then the ASV containing infusion should be stopped immediately. The following drugs should be available before starting the ASV infusion to counter anaphylaxis that may present immediately in such a case.
- Adrenaline 0.5 ml (1:1000)
- Pheniramine maleate
For further information, regarding the first aid management prior to hospital admission, click the following , SNAKE BITE FIRST AID