Clinical Features of Snake Bite:-
• The majority of snake bites are caused by non-venomous species.
• Even highly venomous snakes often bite without injecting any venom.
• Fear, particularly the fear of death, may produce symptoms that can
mimic systemic envenoming.
• Use of a tourniquet may lead to a swollen and damaged limb even in
the absence of envenoming.
• Clinical features of envenoming depend on the species of snake,
the quantity of venom injected and the composition of the venom.
-20 Minute Whole Blood Clotting Test (20WBCT) in the diagnosis and management of viperine bite- 10ml blood of victim in plain vial is checked for clotting after 20min. If not clotted- suggest viper.
Pain management - never give NSAIDs- causes more bleeding.
Never give morphine- can cause respiratory failure.
Envenoming by juvenile and adult snakes of certain species can also
cause different clinical features:--
• Cobra and Krait Bites
Ø Krait bites usually occur at night on sleeping people (often, but not
only on those sleeping on the ground) and may go unnoticed, so
that early morning pain in the abdomen with features of paralysis of
the eye muscles (difficulty to open the eyes) require urgent care.
Ø Cobra bites usually occur in the daytime in Nepal, especially at dawn
Management of Snake Bite:-
Ø Envenoming due to cobra and krait bites manifests itself predominantly
with neuromuscular paralysis (neurotoxicity):
- Ptosis – inability to open the eyes on looking up
- Inability to open the mouth
- Inability to protrude the tongue from the mouth
- Inability to swallow
- Paralysis of the muscles of the hands and feet
- Difficulty in breathing
Ø Choking and inability to breathe may also result from the pooling of
secretions from the mouth, aspiration of vomitus, or blocked airway
by a paralyzed tongue.
Ø Local swelling, local infection, abscess formation and local tissue
damage (necrosis) is one of the important features of cobra
• Viper Bites:--
Ø The most common serious complication of viper bite envenoming is
Ø Bleeding from gingival sulci is usually the earliest sign of systemic
Ø Other common sites of bleeding are partially healed wounds or
Ø In severe envenoming, bleeding from any site is possible.
Ecchymoses (bleeding under the skin), subconjunctival bleeding (in
the eye), intraperitoneal haemorrhage (bleeding inside the abdomen),
subarachnoid and intracranial hemorrhages (bleeding inside the skull
and into the brain) may occur.
Ø Local complications at the bite site are common and may include
swelling, blisters, necrosis of the skin, soft tissues, connective tissues
Venomous Snakes of First Aid:-
• Any person who happens to be nearby at the time of a snake bite, or
the victim himself, should carry out first aid.
• Reassure the victim; most are terrified and apprehensive.
• Immobilization of the bitten limb is an important and effective first aid
measure. Allow the victim to lay down in a comfortable and safe position.
• Immobilize the bitten limb with a splint or sling.
• Immediately transport the victim to the nearest health centre where
antivenom (anti-snake venom serum) is available. This is the most
important first aid measure. Transport by motorcycle or other motor
vehicles is key to save time.
Management at the Health Centre:-
• If the victim has no sign of envenoming, admit the patient, give tetanus injection and observe for 24 hours. If signs of systemic or severe local envenoming are present on admission or develop later, treatment with antivenom and other supportive care is the key to the survival and cure of
• Early assisted ventilation (manually by Ambu bag or mechanically) is
crucial to treat patients with respiratory paralysis. It may be required for
days or weeks but full recovery is possible if adequate oxygen levels
• Immediate Management:--
1. Assess vital signs, resuscitate if necessary and insert an intravenous line.
2. Evaluate for the presence of features of local envenoming.
3. Look for signs of neuromuscular paralysis or bleeding (other than
from the bite site).
4. Certain clinical situations demand urgent resuscitation, e.g.,
presence of profound hypotension and shock or respiratory failure.
5. Pay careful attention to the pre-admission history, closely observe the
patient and be prepared for rapid development of severe systemic
envenoming and sudden deterioration.
6. Snake bite envenoming, especially by kraits, can produce clinical
features that resemble brain death, like fixed dilated pupils and
invisible spontaneous respiration. These patients are paralysed and
can fully recover if adequately ventilated (manually or mechanically).
• Indications for Antivenom Injection:-
1. Signs of neuromuscular paralysis (drooping of eyelids, inability to
open the mouth or other signs described above).
2. Spontaneous bleeding.
3. In proven cases of Russell’s Viper bite: incoagulable (non-clotting) blood.
• Dose of Anti snake venom(ASV):-
Ø Snakes inject the same dose of venom into children and adults.
Children must therefore be given exactly the same dose of antivenom
Ø Patients with signs of systemic envenoming should be treated with
antivenoms (also known as anti-snake venom serum) according to the
-Mode of administration of ASV is IV only.
-The maximum recommended dose for haemotoxic bites in 30 vials of ASV.
-The maximum recommended dose for neurotoxic bites is 20 vials of ASV.
-ASV Reactions- No ASV Test Doses are to be administered.
At the first sign of an adverse reaction the ASV is halted-0.5mg Adrenaline is given IM- ASV remaining dose should be given- Avil & Effcorlin can be given to prevent ASV anaphylaxis.
-Neostigmine works in cobra bite as cobra venom acts on post-synaptic neurons.
Atul Chowdhury, Rapid Action Force