25 - VICC

KYJ25 - VICC Venom induced Consumptive Coagulopathy

Snake bites have always interested me. Perhaps it was my teen experiences with having a pet snake, or the fascination with them being so lethal, but I've always been interested.

The physiology of their venom effects is something that we have come to understand over the last 30 years, and it is surprising that it is just on 30
years since pressure immobisation was introduced.

So let's spend a few episodes of KYJ to grasp the major venom effects of our Australian snakes.

Most common, is the widely known effect of bleeding.

More correctly coagulopathies are classified into consumptive (pro coagulant) coagulopathy and anticoagulant effects.

Classically, species of Taipan, Brown snake and Tiger snakes, cause early wide spread clotting which ironically then leaves the victim unable to coagulate .

This is called venom induced consumptive coagulopathy (VICC).

Snake venom causing VICC has a protein that activates prothrombin to convert to thrombin. Which then causes fibrinogen to be consumed by conversion into fibrin.
Widespread microscopic disseminated micro vascular coagulation takes place and claggs up brain, heart,lung , renal ,hepatic and other organs, leading to organ failure.
 Once all the fibrinogen had been used up, the patient (often still living) now had nil capacity to coagulate, and starts to bleed as though they have had an overdose of Warfarin.

While antivenin halts this process, the danger period is in the hours and days to follow as they are left coagulopathic.

The other form of bleeding effects (seen in Black snakes), is an anticoagulant effect preventing thrombin formation, but other venom effects of these black snakes like myotoxicity and renal impairment (addressed next episode) bear more clinical concerns.

In summary : VICC is early wide spread coagulation, followed by rapid inability to coagulate because of fibrinogen consumption,
Taipans (particularly the Inland Taipans) are the most potent venoms of any snake,