Echinoderm Envenomation Treatment & Management

Prehospital care entails recognition of the injury as a potential envenomation, gentle removal of superficial spines and pedicellaria, direct pressure to control bleeding, administration of analgesia, and transport for medical evaluation.

Recognition of serious systemic symptoms and prompt institution of appropriate life-saving procedures, such as cardiopulmonary resuscitation (CPR) and treatment for anaphylaxis, should be paramount in the prehospital care setting. CPR and advanced cardiac life support (ACLS) are rarely indicated but always take absolute precedence.

While not universally endorsed, several sources recommend pressure immobilization as an early first aid measure for rare cases with suspected anaphylactic reaction. Apply a compression bandage to the affected limb to impede lymphatic flow at a pressure range of 40-70 mm Hg for upper extremities and 55-70 mm Hg for lower extremities (clinically equivalent to comfortable pressure that is neither too tight nor too loose). Immobilization via splinting should follow to limit muscular contraction and the resultant muscle pump effect. In the absence of serious generalized allergic reaction, pressure immobilization bandaging is strongly contraindicated and may be harmful.

Emergency department (ED) management of echinoderm envenomation involves addressing the venom exposure and the accompanying trauma inflicted by the specific application structures used to deliver the venom (spines, pedicellaria, tentacles). General rules of therapy include prompt analgesia, wound management, and observation for and supportive treatment of significant systemic symptoms.

Methods of recommended analgesia are variable but generally include initial treatment with hot water immersion followed by adjunctive local or regional anesthesia and parenteral analgesics, as needed.

Nearly all references recommend initial immersion in nonscalding hot water following the removal of visible spines and sheaths. Hot water immersion to inactivate heat-labile toxins is widely recommended as effective treatment for envenomations by echinoderms as well as stingrays, stonefish, and other venomous marine spine injuries. Immerse the affected limb in water not warmer than 114°F or 45°C.

Exercise caution not to inflict thermal burns by placing an insensate limb (as the result of local anesthesia or decreased sensitivity from pain) in scalding water. Others have noted that immersion in ice water also may provide relief. Local or regional anesthesia is a suggested means of adjunctive analgesia when immersion therapy does not provide sufficient pain relief. Local or regional adjunctive anesthesia offers several benefits, including no risk of inflicting thermal injury; reliable, prompt, and prolonged duration of analgesia; and simultaneous debridement of the wound while providing analgesia. Parenteral analgesics and/or sedatives may be needed for wounds that are difficult to anesthetize or persons who exhibit anxiety reaction to envenomation.

Wound management principles include identification of foreign material, adequate debridement, prophylactic antibiotics when indicated, tetanus prophylaxis, and appropriate referral for retained fragments that are not easily accessible in the ED.

Promptly undertake debridement of loose spines, spicules, and pedicellaria, taking care not to break brittle structures and create retained fragments. Immediate gentle removal of obviously protruding spines prevents further envenomation, penetration, or breakage.

Similarly, to prevent ongoing envenomation, remove all visible pedicellaria as soon as possible by applying shaving foam and gently scraping with a razor. Pull embedded debris straight out with forceps, taking care to avoid bending or jiggling spines that may break off at the tips.

Ultrasound or radiography can help identify retained fragments that may require referral for consideration of operative removal. Surgical removal with proper anesthesia of embedded spines is indicated when in proximity to joints, nerves, or vessels. Spines in weight-bearing surfaces may also require removal to prevent chronic pain.

Retained spine fragments may cause inflammation, become encapsulated, and develop granulomata during the healing process, leading to infection or chronic pain.

Most thin embedded spines are absorbed or extruded through the skin in days to weeks. Not all spines need be surgically removed. Copious irrigation to remove introduced foreign material always should be performed after adequate anesthesia.

Tetanus prophylaxis is indicated in all patients with traumatic marine injuries who have insufficient or uncertain immunization histories.

Ocular exposure to the holothurin toxins of sea cucumbers mandates a careful ophthalmologic examination. Following topical anesthesia, copiously irrigate and perform slit lamp examination to identify and address any retained tentacular fragments, corneal abrasions, or evidence of keratitis. Prompt ophthalmologic referral is indicated.

Systemic symptoms of envenomation are not uncommon and reportedly encompass a wide range of nonspecific symptoms, including nausea, vomiting, abdominal pain, malaise, arthralgias, paresthesias, muscular paralysis, respiratory distress, hypotension, syncope, and, rarely, death.

No antivenom for any of the venomous echinoderms exists. Treatment is supportive.

Although rare, some severe reactions may represent anaphylaxis and should be treated accordingly.

Consultation with an appropriate surgical specialist is advised for all complicated puncture wounds in proximity to articular and neurovascular structures. Spine extraction is best performed acutely and with an operating microscope in the surgical suite.

Plantar puncture wounds are potentially complicated injuries and may require consultation or referral for foreign material not easily extracted in the ED.

Consultation and admission to the general internist for supportive care may be warranted when symptoms of serious systemic envenomation are present. Protracted pain, nausea, muscular weakness, respiratory distress, and hypotension are a few systemic symptoms that may warrant care beyond the scope of the emergency department. Additionally, in the rare case of sepsis caused by Vibrio or Aeromonas species, a coordinated multispecialty effort is needed to address wound debridement, antibiosis, and critical care support.

Urgent ophthalmologic referral is appropriate in cases of ocular exposure to holothurin toxins.