Page 45 - JSOM Summer 2020

Joint Trauma System Clinical Practice Guideline

Global Snake Envenomation Management

Background
Snakebite, recently declared a neglected tropical disease and
global health priority by the World Health Organization (WHO),
results in an estimated 2.5 million envenomations, 138,000 deaths
and over 500,000 cases of permanent disability worldwide every
year. 1–10 Snake, spider, and scorpion envenomations are a common
environmental and occupational hazard for military forces world-
wide. 11–46 The consequences of an envenomation range from mild
local effects to permanent disability or death, and the outcome is
largely determined by the time to antivenom treatment and the kill the snake; treatment is clinical and the snake species does not
level of training of the medical providers involved. need to be identified.
Once an envenomation has occurred, the provider and patient Antivenom fundamentals: There are NO ABSOLUTE CONTRA-
are racing against the clock to neutralize active venom compo- INDICATIONS TO ANTIVENOM for patients with symptomatic
nents before extensive damage has occurred. Necrosis caused by snake envenomations. The high risk of permanent damage posed
cytotoxic venoms cannot be reversed, but it can be prevented by by untreated venom in the body is far greater than the low risk
early antivenom administration or arrested before further damage of anaphylaxis associated with high-quality modern antivenoms.
can occur in cases of late antivenom treatment. 1,7,47,48 Hemotoxic
venoms can induce coagulopathies within 1 hour of the enven- Antivenom administration at the earliest possible opportunity is
omation, which is quickly followed by a standard progression of the gold standard of snakebite care and most effective way to re-
worsening local and systemic external and internal bleeding. Neu- duce the risk of death or permanent disability in these patients.
rotoxic venoms can act rapidly and be fatal. Africa is one of the – Early antivenom administration in the field at or near the point
few places in the world with snakes like the black mamba that are of injury may resolve the underlying envenomation before any
capable of killing a human within 1 hour due to direct effects of serious systemic signs or symptoms develop.
the venom, and most patients with mamba envenomation who – Ignore the packaging and manufacturer insert and treat ac-
are not rapidly treated with antivenom will die within 2–6 hours cording to the guidelines outlined in this CPG.
from respiratory arrest. 1,49 When a neurotoxic bite occurs, rapid – Dosing and administration of recommended antivenoms in
antivenom administration prior to the onset of respiratory mus- this CPG can vary significantly between products; refer to Ap-
cle weakness can arrest the progression of descending paralysis pendix B for specific instructions for each product you have
before serious systemic manifestations develop. 1,50,51 Every hour on hand.
wasted between bite and antivenom administration is strongly as- – Antivenom may be given by IV or IO injection or infusion. 54,59
sociated with sharp increases in mortality and the development of IV is preferable but IO is an acceptable alternative and should
chronic or permanent sequelae including amputation, disfigure- not influence the efficacy of the medication.
ment, PTSD, blindness, kidney injury, infections, and partial or – DO NOT give antivenom by IM or SQ injection, even if pack-
complete loss of function of the bitten limb. 4,7,8,52–58 aging says you can. The serum concentrations of antivenom
These guidelines will cover the continuum of snakebite care for given by IM or SQ injection will never achieve more than a
snake envenomations in all combatant commands. fraction of the serum concentrations rapidly achieved from the
intravascular route.
– DO NOT administer test doses of antivenom to check for hy-
General Principles of Snakebite Management persensitivity prior to giving the full dose. Test doses have no
Snakebite clinical triads: There are three major clinical syndromes predictive value for identifying patients with hypersensitivity
of snakebite envenomation worldwide and three major signs and and waste both time and antivenom. 60–63
symptoms of each. All dangerous snakes capable of injuring or – Antivenom dosage IS NOT WEIGHT-BASED and there is no
killing a human will produce at least one sign or symptom from difference in dosing between adults and children. The dose of
at least one of the three major snakebite syndromes (neurotoxic, antivenom needed to achieve control of the envenomation is
hemotoxic, and cytotoxic). Specific antivenoms required will vary proportional to the dose of venom injected into the patient.
regionally but the major triads are applicable globally. The quantity of venom injected into the patient corresponds to
the severity of the envenomation syndrome(s).
Do not try to ID the snake: Snake identification is unreliable and – Antivenom should be given as many times as needed until con-
should not be purposely attempted. DO NOT attempt to catch or trol of envenomation is achieved.

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