Dr.Sruthi Suresh , Dr.Sajith Kesavan (Paed critical care), Dr.Greeshma(Paed critical care), Dr.C. Jayakumar
AIMS, Kochi
Eight-year-old female child was taken to a local hospital with alleged history of snake bite on her left lower limb. Whole blood clotting time was found to be prolonged and she was given antisnake venom (ASV) 20
She developed sever local sit pain, generalized edema, oliguria with hematuria. Hence referred to AIMS for further management.
On examination, she was conscious and oriented. PR-110/min, RR-28/min, BP-110/60mmHg, SpO2-98% RA, CRT <2 sec, afebrile with facial puffiness, generalized edema and pallor. Left lower limb: bite mark noted over the dorsum of foot, edematous. Left eye- sub conjunctival hemorrhage. Per abdomen- periumbilical and epigastric tenderness.
Figure 1 showing subconjunctival hemorrhage
Figure 2 showing extensive skin changes over the bite site
Blood investigations showed neutrophilic leukocytosis, anemia with raised inflammatory markers with features of DIC (thrombocytopenia, elevated PT, aPTT, D-dimer and prolonged whole blood clotting time). CPK was elevated and LFT showed hypoalbuminemia with hyponatremia. Peripheral blood smear showed leucoerythroblastic picture with 6% atypical cells and severe thrombocytopenia.
Chest X-Ray showed fluid overload.
She also had features of acute kidney injury. ECHO was within normal limits.
She was started on Intravenous Piperacillin, Tazobactam and Metronidazole.
Five more vials of antisnake venomin view of suspected viper bite, albumin, 2 PRBC, 2 FFP and 2 platelet transfusions were given. Thromboelastogram report was suggestive of coagulopathy. Renal replacement therapy was started and she was intubated in view of impending respiratory failure and fluid overload, hypokalemia was corrected. After 48 hours, extubated. Plastic surgeons advised excision of necrotic patch with Vaccum assisted closure (VAC) dressing followed split skin graft in case of worsening. she improved, urine output improved to 4-5ml/kg/hour, hence discharged with stable vitals.
Three thousand species of snakes worldwide are poisonous, chiefly belonging to Elapidae (cobra, krait, coral snake, death adlers, sea snake) and viperidae (rattle snake, saw snake, Russell viper) families.
Venom contains neurotoxins, cardiotoxins, hemotoxins, cytotoxins and causes:
1) Neurotoxicity: ptosis, diplopia, bulbar palsy, dysarthria, generalized weakness
2) Coagulopathy- gum bleeding, epistaxis, intracranial bleeding
3) Rhabdomyolysis with muscle pain, tenderness, dark urine, acute tubular necrosis
4) Hypotension and/ or shock due to vasodilatation, myocardial toxicity with bleeding
5) Tissue necrosis with pain, tenderness, swelling, bleeding and blisters at local site
Management of a snake bite includes:
1)Do it RIGHT:
R- Reassure
I-immobilize the limb
G and H- Get to the hospital
T- Tell the doctor
2) Wound care
3)Whole blood clotting test
4)Anti snake venom
5)Continuous vitals monitoring
6)If established renal failure: dialysis
7) For airway protection or respiratory paralysis: mechanical ventilation
* The foremost priority in the management of snakebite in the emergency room is to support the patient with life-threatening respiratory depression, cardiac failure, or shock.
* Antisnake venom remains the cornerstone in the management of snakebite envenomation. The currently available ASV in India is polyvalent, containing equine immunoglobulins to the four common snake venoms—Russell’s viper, saw-scaled viper, common cobra, and common krait. The immunoglobulins attach to the venom molecule making it unable to bind to the target tissue.
Antisnake venom is produced in both lyophilized form (less rigid cold chain and longer shelf life) and liquid form (less preferable as cold chain is crucial). It should not be used in asymptomatic bites with normal WBCT but must wait for signs of envenomation.
*Indications for Antisnake Venom
-Systemic envenomation: Evidence of coagulopathy: Primarily detected 20-minute WBCT or visible spontaneous systemic bleeding, gums, etc.
-Evidence of neurotoxicity: Ptosis, external ophthalmoplegia, muscle paralysis, inability to lift the head, etc.
-Local envenomation: Severe current, local swelling involving more than half of the bitten limb (in the absence of a tourniquet). In the case of severe swelling after bites on the digits (toes and especially fingers).
*Antisnake venom administration:
Dosage—it is of 10 vials. Each vial is dissolved in 10 mL saline. Total dose is diluted in 10 mL/kg 0.9% saline or 5% dextrose and given as an infusion over 1 hour. The patient should be closely monitored. Keep injection adrenaline 1:1,000; 0.01 mg/kg ready.
* Response to ASV: If an adequate dose of appropriate antivenom has been administered, the following responses occur:
Spontaneous systemic bleeding usually stops within 15 minutes.
Blood coagulability is usually restored in 6 hours.
Postsynaptic neurotoxic envenoming such as the cobra may begin to improve as early as 30 minutes, but can take several hours. Presynaptic neurotoxic envenoming such as the krait usually takes a considerable time to improve.
*Repeat doses: Antihemostatic:
After 6 hours, WBCT is repeated and a further dose 5–10 vials should be administered over 1 hour, if WBCT abnormal.
This 6 hourly pattern (time for liver to replace clotting factors) is repeated until the coagulation is restored.
If 30 vials have been administered and there is no improvement, fresh-frozen plasma (FFP) or factors can be considered. Further ASV should not be given.
*Repeat doses: Neurotoxic:
If the initial dose has been unsuccessful in reducing the symptoms, then a further dose of 10 vials should be administered, after 1–2 hours.
Once the patient is in respiratory failure, has received 20 vials of ASV, and is supported on a ventilator, ASV therapy should be stopped.
*Antisnake Venom in Special Situations
Newborn and small infants: ASV dose is same and independent of weight. But total volume is restricted to 5 mL/kg and given more slowly to prevent fluid overload.
*Antisnake Venom dosage in victims requiring lifesaving surgery: Before surgery, coagulation must be restored to avoid catastrophic bleeding with higher initial dose of ASV of 25 vials.
Victims who arrive late: If coagulopathy is present, administer ASV. In case of neurotoxic envenomation with respiratory failure on ventilator, administer 8–10 vials of ASV to ensure that no unbound venom is present. No need of ASV for ptosis alone persisting without progression.
Source : IAP standard treatment guidelines