of their dorsal and pectoral fins. Venom glands produce heat- labile toxins consisting primarily of proteins. 71 The most common clinical manifestation of fish envenoming is pain. 95-99 Local effects may also include erythema, swelling, ecchymosis, and dysesthesias. Severe envenomations may manifest as headache, hypotension, tachycardia, syncope, vomiting, dyspnea, and weakness. Trauma may also result from penetration of a large stingray spine. Management is supportive. Victims must be safely removed from the water. A patent airway, oxygenation and ventilation, and euvolemia must be ensured. Any embedded barbs should be removed carefully because they may cause additional injury. If the retained spine is tamponading a wound that would otherwise bleed, it should be removed only by a surgeon who can intervene operatively if necessary. An effective, nonpharmacologic method of relieving the pain of these envenomings is to immerse the area in hot water. The ideal temperature range is 42 °C to 45 °C. If a thermometer is unavailable, heat the water as much as an unaffected limb can tolerate, and then immerse the affected limb in the bath. It is recommended to use an unaffected limb to test the water because an envenomed arm or leg may have altered temperature perception, which could lead to a thermal burn. Nonprescription analgesics may relieve mild pain, but opioids are often necessary. Infection is not typical in cases of marine envenomation but may develop if a barb or spine remains embedded in the victim. Meticulous wound care is essential, and empiric antimicrobial therapy with antibiotics such as doxycycline, ciprofloxacin, or trimethoprim-sulfamethoxazole should be considered.
Figure 25. Pterois Volitans
Source: Spencer Greene Venom apparatuses differ among the orders and classes of venomous fish. Stingrays possess one or more serrated barbed spines on the dorsal surface of their tails, measuring from 2.5 cm to more than 12 cm. Venom glands are located on the underside of each spine, which is covered with an integumentary sheath. When the barb enters the victim, the sheath is violated, exposing the venom, which contains a variety of heat-sensitive enzymes and other proteins. Scorpaenidae have spines attached to their dorsal, anal, and pectoral fins. These spines are connected to glands that produce heat-labile venom containing acetylcholine and various proteins. Catfish have similar spines toward the front Cnidarians Cnidarians include corals, sea anemones, hydroids, and jellyfish, and they are widely distributed off U.S. coasts. There is much variation in the animals often referred to as “jellyfish.” Scyphozoans, for example, the Pacific sea nettle ( Chrysaora fuscescens ), are true jellyfish that typically range in size from 2 to 40 cm, but they may grow as large as 200 cm. Box jellyfish, for example, the four-handed box jellyfish ( Chiropsalmus quadrumanus ), are members of the Cubozoa class, which also contains some of the most dangerous cnidarians worldwide, such as the Australian box jellyfish ( Chironex fleckeri ). They, too, are quite variable in size, ranging from 1.5 cm to more than 30 cm. Arguably the most well-known jellyfish in the U.S. is not actually a jellyfish. The Portuguese man-of-war ( Physalia physalis ) is a hydrozoan native to the Atlantic Ocean and the Gulf of Mexico. The related Pacific blue bottle ( P. utriculus ) is found in the Pacific Ocean. These drifting polyp colonies have tentacles that frequently measure up to 10 m and can occasionally reach up to 30 meters. Cnidarians contain stinging cells called cnidocytes , which contain hollow, pointed tubular structures bathed in venom, which consists of hemolytic, cytolytic, cardiotoxic, neurotoxic, and dermatonecrotic polypeptides and proteins such as phospholipases, fibrinolysins, and kinins. There are several hundred of these structures, called nematocytes , found on each tentacle, and some may grow to 1 mm in length, which is large enough to penetrate human skin. Physical contact or a change in the local chemical milieu can trigger the discharge of these nematocytes, leading to envenomation.
Figure 26. Portuguese-Man-of-War (Physalia physalis)
Source: Spencer Greene Pain is the most consistent symptom following cnidarian envenomation. Skin findings include erythema and sometimes vesicles, often in a fern-like or whip-like pattern. Severe envenomations may produce tachycardia, hypotension, nausea, vomiting, abdominal pain, weakness, renal failure, and cardiovascular collapse. 101,102 Uncommon ocular findings include conjunctivitis, chemosis, and corneal abrasions. Cnidaria envenomations are managed supportively in a manner similar to fish envenomations, including hot water immersion. There are no antivenoms for jellyfish that are native to the U.S. The nematocysts should be inactivated and removed. Vinegar or acetic acid in a 4%–6% solution is very effective in envenomings from the lion’s mane jellyfish ( Cyanea capillata ). However, there are laboratory data suggesting that vinegar will increase nematocyst firing in some Physalia species. If rinsing does not remove the tentacles, use forceps rather than grabbing them with a bare hand.
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