Snakes

Front 1

Elapids.
Example?

Most common effect of toxin?

Back 1

Mambas, cobras

Ascending paralysis (Neurotoxic)

Front 2

Vipers.

Examples?

Most common effect of toxin?

Back 2

Pit vipers

Haemotoxic

(think about VHF)

Front 3

Antivenom is lifesaving - why is there a cessation in antivenom supply to Africa?

Back 3

Expensive - >$200 a treatment

AV causes adverse effects (50% patients)

AV is ineffective against local effects.

Front 4

Unsurprisingly. Where does the highest incidence of snakebites occur?

Back 4

Where the highest population density conincides with highest snake density.

Front 5

What occupations are biggest risk factors?

Back 5

Rice farmers, rubber plantations wormers, subsistence farmers.

Front 6

What factors explain why snakebites are low priorities for agencies/research?

Back 6

Resource poor countries only affected.

Rural populations affected - limited political voice.

Patchy geographical problem

Many different species and thus many different clinical syndromes/treatments.
Expensive antivenoms

Front 7

Some major venom components of snakes?

Back 7

Cytotoxins: Proteases, phospholipases

Haemorrhagins (Break down of blood vessels)

Components acting on clotting cacade and platelets

Neurotoxins --> Pre or post synaptics

Myotoxins --> May lead to rhabdomyolysis

Front 8

Seasnake bites. Main issue?

Back 8

Severe myotoxicity.

Front 9

Clinical pattern of envenoming. (5)

Back 9

Some venomous may cause no problems (Up to half of those bitten may have not been envenomed).
Fear may cause Sx which mimic envenoming.

Bites may not be noticed/reported.

Early local Sx --> Pain/Bleeding at bite site --> Swelling/tender LNs

Early Sx of systemic envenoming --> Nausea, vomiting, collapse

Front 10

How does snake venom cause coagulopathy?

Back 10

Very similar to DIC

Consumptive coagulopathy --> All clotting factors used up and then lead to bleeding.

Front 11

How to test for coagulopathy after snake bite?

Back 11

Often no access to clotting tests.
Can use 20 minute whole blood clotting test - leave blood for 20 minutes, if clotted after that time --> sufficient fibrinogen.

Front 12

Neurotoxins

2 different kinds. And why important?

Back 12

Pre-synaptic: Prevent transmitter release destruction of nerve terminals

Post-synaptic: Toxins bind to acetylcholine receptor.

Importance is that you won't get rapid improvement with a pre-synaptic toxin after antitoxin.

Front 13

Signs of neurotoxicity after envenomation? (5)

Back 13

Close and regular observation necessary
Initial ptosis then opthalmoplegia.

Bulbar weakness: Pooling of secretions

Progressive weakness

Eventual respiratory failure --> Paralysis of intercostal muscles and diaphragm

Front 14

Administering antivenom. Key points

Back 14

Slow IV infusion

Dose varies between different antivenoms

Dose does not depend on size and same amount of venom released.

Need to carefully observe antivenom reactions

Front 15

Preventing antivenom reactions: (3)

Back 15

Rare of reaction varies considerably depending on sophistication of production.

Test dose has no value.
Prophylaxis against reactions commonly advocated --> Only evidence is using adrenaline not antihistamines.

Front 16

Monitoring antivenom. What should be done 4-6 hours after treatment?

Back 16

Check whole blood clotting test.

Front 17

Supportive options with envenoming. (5)

Back 17

AIRWAY support.

Plasma expanders for hypotension

Tetanus vaccine

FFP only if antivenom has been given + LIFE threatening bleeding

Anticholinersterases --> Useful in some neurotoxic envenomic.

Front 18

Mechanisms of renal failure during envenomation (3)?

How to manage? (4)

Back 18

Hypotension, Direct renal toxicity, Myoglobin

Antivenom/Fluid balance/Mannitol

Renal support may be necessary.

Front 19

Some simple ways of preventing snakebite.

Back 19

Do not sleep on floor.

Use bednet.

Cut grass short around campsites.

Discourage rats from camps/huts.

WEAR BOOTS!!

Do not corner snakes.

Front 20

Clinical features of Latrodectus (Widow spiders) bites? (3)

Treatment option?

Back 20

Pain --> Local/Regional/Systemic.

May have no systemic envenomic

Non-specific symptoms --> Hypertension muscles spasms, pulmonary oedema.
Antivenom available --> Varying effectiveness

Front 21

Loxosceles spiders (Recluse spiders).

Clinical presentation?

Treatment?

Back 21

Mild pain/erythema/swelling. Can be followed by skin necrosis. Systemic manifestations rare. (Include haemolysis and renal failure)

Antivenom limited availability/effectiveness.

Surgical intervention sometimes necessary.

Front 22

Worst potential for fatality from spider bites?

Where found?

Treatment?

Back 22

Funnel web spiders.
Eastern Australia
Local pain common-systemic envenoming rare.

Can cause arrhythmias/hypertension/pulmonary oedema.

Treatment --> Antivenom available and probably effective

Front 23

Scorpion stings.

Where do venoms tend to act?

Clinical presentation?

Back 23

Venoms act on Na/K channels of neuromuscular tissue

Clinical manifestations: Severe pain, slight swelling.
May then develop autonomic system disturbance, sweating, lacrimation, excessive salivation, ECG changes, cardiac/pulmonary failure.

Front 24

MGMT of scorpion stings? (4)

Back 24

Antivenom

Atropine for bradys

Prazosin for some CVS manifestations

Supportive therapy for heart failure.

Front 25

Mechanism of envenomation from jellyfish?

Systemic envenoming issues? (2)

Back 25

Mechanical contact with nematocysts on tentacles causes injection of venom into prey.

-Chironex (box jellyfish) may cause myalgia, panic, HTN, pulmonary oedema and autonomic disturbance.

-Irukandji syndrome --> Limited local symptoms but late severe generalised pain and HTN

Front 26

Marine envenoming from fish spines.
Symptoms?
Treatment?

Back 26

Sx - Extreme pain!!!! Some cause systemic envenoming.

Tx --> Immerse in hot water and possibly nerve block.