Poisoning snake2012+MCQs.

1. SNAKE BITES/scorpion stings
 Snake bite is common life-threatening in many countries.
 Farmers, hunters, rice-pickers are at particular risk
 Prompt medical treatment is vital.
 3-5 million victims /year, 50 000 deaths , 400 000 amputations.
 40% of bites do not produce signs of envenoming.
 It is difficult to predict which bites will produce symptoms or
the clinical outcome, all victims should be brought under
medical care as quickly as possible.
 Poisonous species of snake fall into the families.
 Snake venoms are complex mixtures of proteins & small
polypeptides with enzymatic activity.
 Snake venoms are neurotoxins, haematotoxins (haemorrhagic
or coagulopathic) or cardiotoxins often occur in combination.

2. Clinical features & assessment
 Key questions to ask a victim are:
 The body part bitten?
 How long ago?
 What sort of snake?
 Friends / relatives will frequently bring the snake with the
patient; it should be handled as little as possible since it may
only be injured rather than dead.
 The amount of venom injected via a bite is highly variable,
depending on the length of time since the snake last ate& its
aggression.
 Snake venom detection kits are available in some countries.

3. Clinical features & assessment
 The venom is detected from a dry swab of the bite site using
monoclonal antibody techniques.
 The 20-minute whole blood-clotting test is a useful bedside
tool in remote areas; a 2-3 ml sample of venous blood from the
victim is left undisturbed at ambient temperature for at least
20 minutes.
 The vessel containing the blood is then tipped once & may be
compared with a normal control.
 If it has not clotted, there is haemostatic disturbance from
systemic envenoming.
 All patients should have a full blood count, urea/electrolytes,
liver function tests, creatine kinase, troponins, ECG.

4. Clinical features & assessment

5. Clinical features & assessment

6. Management:
 Reassuring the patient
 Immobilising the bitten area to minimise venom spread
 Identifying the snake.
 Application of a firm bandage to occlude lymphatic drainage
is appropriate, but tourniquets are unhelpful since they do not
prevent the spread of venom & frequently applied incorrectly.
 Incisions at the bite site &attempts to suck out the venom by
mouth should not be made.
 A large-bore IV cannula inserted on an unaffected limb.
 BP, coagulation,renal, neurological, cardiorespiratory status
must be monitored, as hypotension, anaphylactic shock, renal
failure, respiratory distress may develop rapidly.

7. Management:
 All patients with suspected envenoming should be observed
for 12-24 hours, as the initial manifestations may be delayed,
especially with elapid bites.
 Pain/ vomiting should be managed symptomatically.
 Aspirin should not be used ,may aggravate bleeding.
 In severe coagulopathy with thrombocytopenia causing DIC,
large quantities of fresh frozen plasma, cryoprecipitate ,
platelets are required if the response to antivenin is poor.
 The most appropriate therapy is timely administration of the
species-appropriate antivenin when indications.
 Before starting antivenin, ask about history of allergy &
intradermal sensitivity test performed by injecting 0.02 ml of
saline-diluted antiserum at a site distant from the bite.

8. Management:
 The inj site is observed for at least 10 mins for the redness,
hives, pruritus or other adverse effects.
 The shorter the interval between inj & reaction, the greater
the degree of sensitivity.
 0.5 ml 1:1000 adrenaline must be available when antiv given
 A negative skin test does not rule out a reaction following
administration of the full antivenin dose.
 The rate antivenin should be based on the severity of the
case& the patient's tolerance to the antivenin.
 The entire initial dose should be given as soon as possible
within 4 hours of the bite.
 In severe envenoming, antivenin given up to 24 hours after the
bite has been shown to reverse coagulation deficits.

9. Management:
 INDICATIONS FOR ANTIVENIN ADMINISTRATION IN
SNAKE BITES
 Cardiogenic shock
 Spontaneous systemic bleeding
 Incoagulable blood
 Neurotoxicity
 Haematuria
 Other evidence of haemolysis/rhabdomyolysis
 Rapidly progressive extensive local swelling
 Bites on digits by snakes with known necrotic venoms

10. SNAKE BITES
 There are three types of antivenin reaction:
 Early anaphylactoid
 Pyrogenic
 Late.
 If an immediate anaphylactoid reaction occurs,
administration of antivenin should be immediately
discontinued &the patient given an oral antihistamine or IM
adrenaline ( 0.5 ml of 1:1000) as appropriate.
 Infusion of the antivenin can be restarted, but at a slower rate.
 Corticosteroids are commonly given to treat serum sickness,
although their value remains to be established.
 Bites by large snakes may need relatively high antivenin doses,
particularly in children or small adults.

11. SNAKE BITES
 Additional antivenin (e.g. the contents of 1-5 vials) should be
administered if swelling progresses or if systemic features of
envenoming increase in severity & new manifestations such as
hypotension or reduced haematocrit appear.
 The use of ancillary drugs, such as anticholinesterases for
neurotoxic envenoming, remains contentious.
 If pulses are lost in a bitten limb, compartment syndrome
should be suspected & surgical assessment requested.
 Wound débridement& later skin grafting are occasionally
required, especially in cobra & viper bites, but should never
be carried out until the coagulation profile is normal.
 Awareness &avoidance of the habitat of snakes are the major
means of preventing snakebite.

12. SNAKE BITES

13. SNAKE BITES

14. SCORPION STINGS
 The most important venomous animals after snakes.
 Most scorpion species produce a venom which causes only
minor local reactions in humans, but in Mexico, Tunisia,
Algeria, Morocco, Libya scorpion stings are a serious health
hazard.
 Scorpions do not attack humans& escape when disturbed.
 Stings occur after a person accidentally steps on or
involuntarily presses the scorpion (when it is trapped inside
shoes or clothes) or when reaching under dead wood or stones.
 Clothes / shoes need to be inspected closely & shaken& sitting
or sleeping places checked when camping in rural districts
where scorpions are common


15. SCORPION STINGS
 Two types of scorpion venom exist:
 1.Venom of genera Hadrurus, Vejovis, Uroctonus only effects,
including sharp burning, swelling, discoloration,very rarely,
anaphylaxis.
 In envenoming by more poisonous species, Leiurus, common
in the M. East, systematic manifestations develop, transfer to
ICU required.
 2. Venom, of genera of the poisonous varieties of
Centruroides / Mesobuthus, contains neurotoxins block sodium
channels& leads to spontaneous depolarisation of
parasympathetic &sympathetic nerves results in tachycardia,
hypertension, sweating, piloerection, hyperglycaemia & pulm
oedema (esp Mesobuthus species)& seizures.

16. SCORPION STINGS
 The sharp pain after a sting is quickly followed by
paraesthesiae& numbness in the area due to peripheral nerve
effects, muscle fasciculation& finally drowsiness.
 With Centruroides& Mesobuthus there is no swelling at the
sting site.

17. SCORPION STINGS: Management
 Local pain & paraesthesiae are best treated with local
compresses & oral analgesics.
 Patients with significant envenoming should be hospitalised
for at least 12 hours& observed for cardiovascular /
neurological sequelae.
 More severe symptoms may require airway support& 1-2
vials of IV antivenin.
 The effectiveness of antivenin is controversial, but it is
beneficial in the very young, the elderly or those with severe
hypertension.
 True anaphylaxis to antivenin occurs rarely.
 Serum sickness is common after antivenin but is usually self-
limiting & easily controlled with corticosteroids/histamines.

18. SCORPION STINGS: Management
 Tachyarrhythmias can be treated with IV metoprolol or
esmolol.
 Prazosin, an α-adrenoceptor antagonist, is indicated if
hypertension or pulmonary oedema develops.
 Prazosin also stimulates the secretion of insulin (which often
falls during envenoming) & prevents hyperglycaemia.
 Other treatments, as calcium or sympathomimetic drugs, are
of little value.

19. SCORPION STINGS: Management

20. SCORPION STINGS: Management

21. Single-choice Qs:
1. The most useful bed-side test to suggest snake bite
envenemoation is:
A. Prothrombin time.
B.20 minute whole blood clotting test.
C. INR.
D.Plateletes count.
E. PTT.

22. Single-choice Qs:
2. Management of snake bite includes all except:
A.Immobilize the bittenpart.
B. Apply a firm bandage.
C. Incision & sucking of the bittensite.
D. IV cannula on unaffected limb.
E.Reassure the ptient.

23. Single-choice Qs:
3.The following features occur in scorpion sting rather than snake
bites except:
A. Piloerrection.
B.hypoglycemia.
C.Hyperglycemia.
D. Hypertension.
E.siezures.