Pediatric emergency medicine trisk 2019 2019
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secretion (e.g., long, healthy fangs or full stores of venom) add to the toxicity of
the bite. An angered and hungry rattlesnake unloads more venom than a recently
satiated and surprised rattlesnake. It is important for the emergency provider to be
aware that coral snake venom may be absorbed without a bite through routes such
as the ocular mucous membranes, which can lead to severe neurotoxicity. Since
the FDA-approved coral snake antivenin is in limited supply, clinicians should
consider non–FDA-approved alternative antivenins as well as adjunctive
pharmacologic treatments such as neostigmine, under the guidance of a
toxicologist.
Clinical Recognition
Generally, it is useful to have a photograph of the snake responsible for the attack
when possible, since it can be shared with an expert and used for identification
and further management.
Pit viper. A Crotalus envenomation causes intense local pain and burning
within a couple of minutes. Victims of a significant rattlesnake bite often
complain within minutes of perioral numbness, extending to the scalp and
periphery, with a metallic taste in the mouth. Local ecchymoses and vesicles
usually appear within the first few hours, and hemorrhagic blebs are often present
by 24 hours. Lymphadenitis and lymph node enlargement may also become
apparent. Without appropriate therapy, there may be progression to necrosis that
may extend throughout the bitten extremity. Secondary infection is a risk as the
snake’s oral flora includes gram-negative bacteria. Table 90.22 summarizes local
characteristics of pit viper bites.
Patients may have nausea, vomiting, weakness, chills, sweating, syncope, and
other more ominous symptoms of systemic venom absorption such as bleeding,
angioedema, and hypotension. A copperhead or pygmy rattlesnake envenomation
produces fewer local symptoms, and systemic consequences are often minimal or
nonexistent unless a small child, multiple bites, or larger than average snake is
involved. The water moccasin’s effects are more variable.
There is a relative lack of serious pain or swelling with the Mojave rattlesnake
bite, although, as in other Crotalus bites, the patient may complain of paresthesia
in the affected extremity. Within several hours, these patients may develop
neuromuscular symptoms such as diplopia, difficulty in swallowing, lethargy,
nausea, and progressive weakness from the large dose of neurotoxin delivered by
this species.
