Envenomation Flashcards
What routes can toxins take on the body?
- Intravenous
- Inhalation
- Intraperitoneal
- Subcutaneous
- Intramuscular
- Intradermal
- Oral
What types of toxins are there?
- Neurotoxins
- Postsynaptic toxins
- Myotoxins
- Locally acting toxins
- Haemotoxins
What are the 3 basic workings of neuro toxins?
- Block/prevent nerve conduction
- Spontaneous action potentials
- Abnormalities of acetylcholine release – pre-synaptic toxins
What are some effects of neurotoxins?
- Neuromuscular paralysis associated with respiratory failure
How do the toxins found in blue ring octopus and puffer/toad fish work on the body system?
- TTX released prevents the action potential propagation by Na+ channel blockade.
What effects are seen from the Sydney funnel web spider?
- The Atraxotoxin will cause
o Gross muscle twitching
o Catecholamine release and glandular hypersecretion
The above is due to the development of spontaneous action potentials that are uncontrollable. These occur throughout the skeletal and autonomic nerves.
What spider is the alpha-latrotoxin seen in?
- The red back spider
What does the alpha-latrotoxin do to the body?
- Depletion of the pre-synaptic vesicles
- The above results in patchy muscle paralysis and catecholamine release.
What type of toxin is seen in all Australian snakes?
- Postsynaptic toxins
- They will block post-synaptic acetylcholine receptors causing paralysis
- Has rapid onset – but also rapid relief if anti-venom is administered.
What are the effects of Myotoxins?
- They affect the muscles
- May cause rhabdomyolysis and potential for renal failure
- Common in Australian snakes
How are locally acting toxins seen in snake venom affect the body?
- Result in the following o Local pain o Oedema o Necrosis o Possible headaches o Systemic myalgia – pain in muscle/group of muscle
How are locally acting toxins seen in marine venoms affect the body?
- Sever pain
- Ischemia
- Cyanosis – blueish apperance
- Necrosis
What is necrotising arachnidism?
- The area around the bite becomes oedematous and necrotic over a couple days.
- Seen in the white tail spider.
What is seen in Haemotoxins?
- Pro-coagulation
- Anti-coagulant activity
- Haemolysis
- Platelet effects
What is the process of envenomation?
- Snake strike occurs and venom is deposited in the form of an avascular liquid or blobs.
- Depending on the venom type – pain/tissue damage will occur at site of the bite.
- For the venom to move centrally It must enter through the following:
o Blood vessels
o Lymphatic system
o Tissue planes. - Regional lymph nodes become enlarged and tender after a venomous bite.
What are you more likely to die from in a snake bite? Anaphylaxis or the venom?
- Anaphylaxis
What venomous effects does the Australian brown snake have?
- Pro-coagulation, Nephrotoxicity, Paralysis, Haemolysis
What venomous effects does the Australian Tiger snake have?
- Rhabdomyolysis, Pro-coagulation, paralysis, Haemolysis
What venomous effects does the Australian Red bellied black snake have?
- Rhabdomyolysis, pro-coagulation, paralysis
What venomous effects does the Australian copperhead snake have?
- Rhabdomyolysis, Anticoagulation, Paralysis
What are common signs of a snake bite wound?
- One ore two small puncture wounds approx. 1cm apart.
- Bleeding and venom residue – will appear as milky fluid.
- Pain, swelling and redness around bite site.
- Bite site may not be visible to naked eye or will present as a scratch.
How will a Pt present with a snake bite?
- N + V
- Difficulty in breathing
- ACS, headache, visual disturbances
- Loss of consciousness
- Chest and abdominal pain
- Paralysis and convulsions
- Acute renal failure
- Rhabdomyolysis
- Ptosis – dropping of upper eyelid.
S&S <1-hour post snake bite if left untreated?
- Headache
- N+V
- Abdo pain
- Hypotension with confusion
- LOC
- Regional inflammation
- Tender lymph nodes
S&S 1-3 hours post snake bite if left untreated?
- Cranial nerve paralysis
- Haemorrhage from mucosal surfaces / puncture site
- Tachycardia / hypotension
- Tachypnoea / shallow tidal volume
