2. Snake bite:
It is a common emergency in our hospitals,
patients usually come from the rural areas, most of the
time they are aware of the snake species.
Common types of poisonous
snakes:
Poisonous species of snake fall into three
families:
1.Viperideae: such as russel viper, pit viper.
7. Pathogenesis and clinical features:
Poisonous snakes have a pair of enlarged
teeth called fangs in their upper jaws that inject venom
into the tissues of their victim.
Snake venomes are complex mixture of proteins and
small polypeptides with enzyme activity.
8. 1. Viperidae:
• Local swelling , echymosis and
blistering at the site of bite.
• Systemic involvement within 30 minutes
including vomiting, hypotension and shock.
• Bleeding and clotting
disturbances(coagulopathy).
• Bleeding gums or bleeding may be fatal.
9. Elapidae:
• Usually no swelling at the site of bite.
• Vomiting and salivation
• Hypotension resulting from loss of
intravascular fluid into thr soft tissues.
• Neurological symptoms include muscle
weakness causing ptosis, diplopia and dysphagia
with paralysis of respiratory muscles in severe
cases.
• Myocardial depression causing reduced cardiac
output and rhythm disturbances.
11. Investigations:
Blood grouping and cross matching as
soon as possible before the effect of circulating
venom interfere the blood grouping
• CBC to evaluate degree of hemorrhage and
hemolysis.
• Urea creatinine and electrolytes for renal
status.
• Liver function tests(LFTs)
• Pt INR
• Urine analysis for hemoglobinuria and
myoglobinuria
12. • ABGs may be required in severe cases.
• ECG to look for rhythm disturbances.
• Chest x.rays
13. Management:
• All patients with suspected snake
bite should be observed for 12_24 hrs, as initial
manifestations may be delayed especially with
elapid bites.
• Reassuring the patient, not all snakes are
poisonous and even bite by the poisonous snake
may be "dry bite" no venome in the bite.
• Try to identify the type of snake.
14. • Immobilized the bitten area to minimize the
venom spread.
• Use of tourniquet is discouraged because they
donot prevent spread of venom.
• Incisions at the site of bite and attempts to suck
out the venom with mouth should not be made.
• Aspirin should not be used for pain since this
may aggravate bleeding.
15. • Monitor blood pressure, coagulation, renal,
neurological and cardiorespiratory status.
• Large bore IV canula should be inserted on un
affected limb.
16. Antivenin(antivenom):
• Antivenome is indicated in patient with
severe or progressing local tissue reaction at the
site of bite , clinical or laboratory evidance of
systemic involvement.
• In about 50% of snake bites no venom is
injected(dry bite) and antivenoms are generally
not indicated, However when indicated antivenom
should be given early, as the antivenoms only
neutralize the venom they can not reverse the
effect of venom. Allergic reaction is the frequent
complication of antivenom.
17. • Antivenom should be give slow IV , the same dose
being given to children and adults.
• Before starting antivenom a test dose is given 0.02ml
of saline diluted antivenom is injected subcutaneously
and observed for at least 10 mints for redness, hive,
pruritis or other allergic reactions.
• A syrenge containing 0.5 ml of adrenaline must be
available to combate anaphylaxis whenever antivenom
is administered. Adrenaline is given subcutaneously.
18. • However skin test doesnot always predict which
patients will have allergic reaction to antivenom.
• IV histamine and ranitidine should be given
before starting antivenom infusion to limit the
acute allergic reaction.
• In severe cases the antivenom infusion should be
continued even with allergic reaction with close
control conditions and premedication with
adrenaline , antihistamine and steroids.
19. • Antivenom should be diluted in 1000ml of saline
or Ringer,s lactate or 5% dextrose water and should
be given slowly, in children 20ml/kg.
