1. Bamboo Snake Bite with DefibrinationBy
Dr. Wong Oi Fung

2. Case History 5/F Attended A&E of TMH at 22:13 on 7/9/2004
Bamboo snake bite over dorsum of right foot at 21:45 on 7/9/2004
Vital signs: pulse 110/min; afebrile; GCS 15/15
Cat. 3
Disposal: admitted into pediatric ward for further management

3. Progress Initial assessment: Alert and conscious
2 small fang marks over dorsum of right foot
No obvious swelling over other parts of lower limb
Circulation and pulse--->normal
Other systems--->normal

4. Progress…….. Initial investigation: CBP, L/RFT--> normal
INR--> 1.1
Fibrinogen-->low
D-dimer-->high
Cardiac enzyme--> normal
ECG-->no arrhythmia

5. Progress…….. Treatment: Antivenom Tetanus booster
One dose given ( in view of rapid progression of local reaction)
Tetanus booster
Antibiotics (Cloxacillin, Claforan, Flaygl)

6. Progress…….. Outcome of initial treatment
Significant swelling over right lower limb from toe to thigh noticed
??Pulses of dorsalis pedis and popliteal artery were negative
Capillary refill ~ 1 sec
Orthopedic surgeon consulted and suggested for conservative treatment

7. Progress…….. Further Investigation USG of right lower limb done:
femoral and popliteal veins patent
no intraluminal filling defect
no fluid collection

8. Progress……...
Transferred to PICU for close monitoring (11to 16/9/2004)
Developed prolonged INR >4.5
Given repeated doses of antivenom and FFP
First 2 doses from Shanghai institute; last dose from Thai Red Cross
INR return to 1.2 on 14/9/2004
Discharged on 18/9/2004
Defaulted WFU on 24/9/2004

9. Progress of blood result and Therapy given

10. Discussion

11. Discussion Why the patient developed prolonged defibrination??
?? Highly potent venom of the snake
?? High venom load per body mass ratio
?? Administration of coagulation factors for the unneutralized venom produced more degradation products, which are also anticoagulant
?? Antivenom from Shanghai institute was not potent enough

12. Discussion General information for snake bite:
~3000 species of snake found worldwide
~15 % considered to be dangerous to humans
14 common venomous species in Hong Kong
White-lipped pit viper/ bamboo snake is the commonest species involved ~95%
Often occurs in summer and autumn

13. White-lipped pit viper snake (Trimeresurus albolabris)
General information:
vipers are venomous snake
generally short with thick body
2 subfamilies :
typical vipers ( Viperinae) e.g. Russell’s viper
pit vipers ( Crotalinae) e.g White-lipped pit viper

14. Descriptions of Bamboo Snake
Length-->15 to 25 inches; max. 36 inches
Female >male
First upper lip shield fused with nasal shield
White lateral line in males only
Upper lip is pale green, yellow or white
Body is green
Iris are yellows
Tail is dark red

16. Clinical Features for bamboo snake envenomation
Degree of illness :
>20% are dry bite
Amount of venom injected
Size of snake
Mechanical efficiency in which the bite occurred ( e.g. both fangs penetrated the skin, repeated strikes)
**repeated bites do NOT result in a depletion of venom stores.**
Primary effect--->coagulopathy, thrombocytopenia, hypotension and local swelling

17. Venom properties
Chemically complex mixtures of proteins ranging from 6 to 100KD
Highly stable, resistant to temperature changes, drying and drugs
80 to 90 % of viper venom and 25 to 70% of elapid venom consists of enzymes e.g. phospholipase A.
damages mitochondria, red blood cells, leucocytes, platelets, peripheral nerve endings, muscle, vascular endothelium, produces presynaptic neurotoxic activity, opiate-like sedative effect, autopharmacological release of histamine

18. Viper venoms Causes haemostatic defects by
Venom procoagulant enzymes activate the blood clotting cascade at various sites
Thrombin-like fibrinogenases remove fibrinopeptides from fibrinogen directly
Activate endogenous plasminogen
Inhibit platelet aggregation
Combination of consumptive coagulopathy, defibrination, thrombocytopenia, vessel damage result in massively incontinent bleeding

19. Clinical Features for bamboo snake envenomation
Local effect:
Immediate severe pain, erythema and swelling
Tissue necrosis due to proteolytic enzymes and phospholipases A
more likely to develop in fingers and toes due to poor systemic absorption
Blistering eruption
presence of blister more likely to lead to necrosis or secondary infection
Local infection of wound

20. Clinical Feature for bamboo snake envenomation
Systemic effect:
Haematological:
Disseminated intravascular coagulation DIC due to the disorder of platelet aggregation and coagulation-fibrinolysis system
Increased fibrin degradation product (FDP), increased APTT and PT, thrombocytopenia
Systemic bleeding or local bleeding

21. Clinical Feature for bamboo snake envenomation
Musculoskeletal:
Rhabdomyolysis ( Russell’s Viper )
Compartment syndrome (rare after viper bite)
Cadiovascular:
Hypotension
Arrhythmia due to myocardial toxicity
Respiratory:
Not characteristic of viper envenomation
May occurred after Russell’s viper bite

22. Clinical Feature for bamboo snake envenomation
Neurological:
Cerebral hemorrhage
Endocrine:
Sheehan’s syndrome (anterior pituitary gland haemorrhage) in Russell’s viper bite
GI:
Nausea, vomiting and abdominal pain
Renal:
Acute renal failure; hyperkalaemia
Other: e.g. anaphylaxis

23. Management in AED Physical Examination: Local signs: Systemic signs:
fang marks, swelling, ecchymosis, blister, bleeding, skin necrosis, sign of compartment syndrome, regional lymphadenopathy
Systemic signs:
severe coagulopathy e.g. gum bleeding, epistaxis, haematuria, GIB
hypotension
paralysis

24. Management in AED Investigation:
Blood testes: CBP, L/RFT, Clotting profile, muscle enzyme, Cross-match
Urinalysis for haemoglobin/myoglobin
ECG +/- CXR
+/-FVC if available

25. Management in AED Release bandage for examination Analgesic
Ideally pressure dressing should NOT be removed until:
patient is at a medical facility
resuscitation equipment is at bedside
antivenom therapy has begun if systemic envenomation present
Analgesic
Aspirin and NSAID is CONTRAINDICATED
Wound management
Tetanus prophylaxis, antibiotic +/- debridment

26. Management in AED Close monitoring:
Any patient who has been bitten by a proven or suspected venomous viper should be admitted into hospital or stay in observation ward for close monitoring for at least 12 hours
Repeat the measurements of extent of swelling and ecchymosis
Close monitor distal circulation
Repeat CBP, RFT and clotting profile every 6 hours( avoid arterial puncture)
Urine output+/- cardiac monitoring

27. Management……. Administration of FFP, platelet count if indication
Renal replacement therapy
Ventilation support

28. Assessment of Severity Envenomation for Viperidae
Degree
Clinical features
Treatment
No envenomation
Asymptomatic
Fang marks, but no local or systemic features after 6 hours from time of accident
Observe for 12 hours (from time of accident) in Observation Ward.
Baseline investigations.
Mild
Fang marks, pain, swelling less than 10cm on presentation and no significant progression after 6-12 hrs.
No significant systemic symptoms.
Observe for 24 hours.
Baseline investigations. Repeat test 4-6 hours later if evidence of progress.
Moderate
Fang marks, moderate pain and swelling more than 10cm in first hour. May have petechiae or ecchymosis of bite area. Occasional minor systemic symptoms.
Admit into hospital for close observation and supportive treatment.
May need Antivenin treatment.
Severe
Marked progressive swelling and pain. Early ecchymosis and blistering. Systemic symptoms and coagulation defects.
Admit into hospital for observation and treatment, preferably in ICU. Need Antivenin Tx.

29. Antivenom therapy Indications: Severe local envenomation
Systemic Toxicity
Coagulopathy
Rhabdomyolysis
Neurotoxicity
**Antivenom can reverse systemic envenomation even after several hours after bite but is NOT effective for local envenomation unless given within several hours after bite**

30. Administration of Antivenom
From Thai Red Cross or Shanghai institute
Dilute before infusion
Slow rate
Preferably in ICU for close monitoring

31. Response to antivenom
Often marked symptomatic improvement soon after administration
Spontaneous systemic bleeding usually stops within 15 to 30 min
Restoration of blood coagulability within 6 hours
Recurrence of systemic envenomation may be due to the continuing absorption of venom form the injection site
Half-life of antivenoms range from 26 to 95 hours

32. References
Dr. WS Ng. COC guidelines for Management of snake bites (revised September 2000)
Gold, BarryS.; Dart, Richard C.; Barish, Robert A. Current Concepts: Bites of Venomous Snakes. The New England Journal of Medicine. Vol. 347(5), August 2002, 347 to 356
Poisindex Management : Asian Snakes-Viperidae
Oxford Textbook of Medicine 4th edition Vol. 1 pp923 to 936

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