Pediatric emergency medicine trisk 1997 1997
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Current evidence. Stingrays are the most important group of venomous fishes,
accounting for an estimated 1,000 attacks per year in North America. Stingrays
are bottom feeders that bury themselves in sand or mud of bays, shoal lagoons,
and river mouths. They are found along the Atlantic, Pacific, and Gulf coasts and
range from several inches in diameter to more than 14 ft in length. Six different
species are represented in North American waters. Envenomations usually occur
when an unsuspecting swimmer steps on the back of the animal and causes it to
hurl its barbed tail upward into the victim as a reflex defense response. Most
injuries are confined to the lower extremities, although wounds to the chest and
abdomen have been reported.
The venom apparatus consists of a serrated, retropointed, dentinal caudal spine
located on the dorsum of the tail. Spines vary in length, depending on the size of
the ray, but may reach a length of 122 cm in some species. The spine is encased
in an integumentary sheath that contains specialized secretory cells that hold the
venom. When the stingray’s barb strikes the victim, it easily penetrates the skin,
rupturing the integumentary sheath over the spine and causing the venom to pass
along the ventrolateral grooves of the barb, into the wound. The barb is
retropointed, so the wound it produces is a combination of puncture and
laceration. Wounds may vary in length from 3.5 to 15 cm. Life-threatening
puncture wounds may occur that require immediate resuscitation. The venom is a
heat-labile toxin that depresses medullary respiratory centers, interferes with the
cardiac conduction system, and produces severe local pain.
The sting is followed immediately by pain, which spreads from the site of
injury during the next 30 minutes, peaks within 90 minutes, and lasts up to 48
hours. Syncope, weakness, nausea, and anxiety are common complaints due to
effects of the venom and the vagal response to the pain. Vomiting, diarrhea,
sweating, and muscle fasciculations of the affected extremity may also occur.
Generalized cramps, paresthesias, hypotension, arrhythmias, and death may
occur. The wound often has a jagged edge that bleeds profusely, and the wound
edges may be discolored. Discoloration may extend several centimeters from the
wound within hours after injury and may subsequently necrose if untreated.
Often, parts of the stingray’s integumentary sheath contaminate the wound.
Treatment is aimed at treating shock, direct pressure to control bleeding,
preventing complications of the venom, alleviating pain, and preventing
secondary infection. At the scene, the wound should be irrigated with cold
saltwater as this can remove much of the venom. Remnants of the integumentary
sheath should be removed if it can be seen in the wound. The extremity should be
placed in hot water (40° to 45°C [104° to 113°F]) for 30 to 90 minutes. After
