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Venomous Bites and Stings

Category: Trauma Sources: raw/protocols/nm-sop-guidelines-treatment-2022.pdf Last updated: 2026-04-04

Overview

New Mexico is home to several venomous species including western diamondback rattlesnake, Mojave rattlesnake, and other pit vipers (crotalids), as well as the Sonoran Desert toad, black widow spider, and brown recluse spider. Prehospital management focuses on scene safety, wound care, extremity stabilization, and rapid transport — antivenom is a hospital intervention. The vast majority of snakebites in NM are crotalid (pit viper) envenomations with localized tissue damage that can progress to systemic toxicity.

Key Points

  • Scene safety: never attempt to capture or handle the animal; even a decapitated snake head can envenomate for up to 90 minutes
  • Do NOT apply a tourniquet to an envenomated extremity (except for uncontrollable hemorrhage)
  • Do NOT cut and suck the wound — ineffective and causes additional injury
  • Do NOT apply cryotherapy (ice) to the wound — worsens tissue damage
  • Do NOT apply a constriction band — tissue damage from venom does not benefit from restriction
  • Envenomation severity varies widely — "dry bites" (no venom injected) occur in ~20–25% of snakebites
  • Rapid onset of severe symptoms = major envenomation; requires expedited transport and ALS
  • Anaphylaxis can develop with any venomous bite/sting — treat per anaphylaxis protocol if systemic allergic reaction occurs
  • Black widow spider: neurological symptoms (pain, muscle cramps, hypertension, diaphoresis); no local necrosis
  • Brown recluse spider: local tissue necrosis (necrotic ulcer developing over days); systemic symptoms rare but possible

Assessment Relevance

History (history-taking): - Type of animal if safely identified (crotalid/rattlesnake vs. copperhead vs. coral snake vs. spider) - Location of bite and time of bite - Onset and progression of signs and symptoms - Any treatment administered before EMS arrival (tourniquets, cutting, sucking — document and manage complications) - SAMPLE: Allergies (to antivenin?), prior envenomations, medications (anticoagulants worsen bleeding), last intake

Physical exam (secondary-assessment): - Bite location: identify fang marks, stinger, or bite wound; document number and location - Local signs: swelling, ecchymosis, hemorrhagic bulla formation (rapid = major crotalid envenomation), tissue necrosis - Neurovascular status distal to bite: pulses, capillary refill, sensation, movement - Systemic signs: nausea/vomiting, diaphoresis, altered LOC, hypotension (crotalid envenomation shock), ptosis/diplopia/difficulty swallowing (coral snake neurotoxin), severe muscle cramping (black widow) - Airway: anaphylaxis can develop — assess for stridor, angioedema - Mark the border of swelling with a pen and note the time — progression rate is a severity indicator

Procedures

  1. Scene size-up (scene-size-up): ensure scene safety; do not attempt to handle or approach animal
  2. Primary assessment (primary-assessment): assess LOC, airway, breathing, circulation; watch for anaphylaxis
  3. Remove jewelry from affected extremity immediately — edema develops rapidly
  4. Immobilize and keep affected extremity at heart level (neither elevated nor dependent)
  5. Irrigate bite wound with sterile isotonic solution or sterile water
  6. Keep patient calm and still — minimize activity to slow venom spread
  7. Transport immediately — do not delay for field treatment
  8. Contact Medical Control and receiving facility
  9. If anaphylaxis develops: epinephrine-auto-injector and anaphylaxis protocol
  10. IV/IO access en route (ALS scope); fluid resuscitation if signs of hypoperfusion
  11. Pain management en route (ALS scope)
  12. Continuous reassessment (reassessment): monitor swelling progression, vital signs, LOC

NM Protocol Notes

From NM EMS Treatment Guidelines (2022) — Venomous Bites:

EMT-B and all levels scope: - Assess scene for safety; remove patient to safe area for assessment - Primary assessment; manage airway, breathing, circulation - Manage bite wound and extremity: - Remove jewelry from affected area - Stabilize extremity and place at the level of the heart - Irrigate bite with sterile isotonic solution or sterile water - Transport immediately to appropriate medical facility - Keep patient calm and still - If anaphylaxis develops: follow Allergic Reaction/Anaphylaxis Guidelines (epinephrine IM) - Enroute: IV/IO in unaffected extremity (flow rate per patient condition)

Pain medications (ALS/EMT-I/P scope): - MORPHINE: Adult 4–10 mg slow IV/IO titrating 2–4 mg every 10 min (max 10 mg without Medical Control approval); do not give if SBP <100 - FENTANYL: Adult 25–100 mcg slow IV/IO every 5 min (max single dose 100 mcg, max total 300 mcg without Medical Control approval) - Anti-emetic: Ondansetron 4 mg IV/IO/PO/IM (adult); 0.05–0.1 mg/kg (pediatric, max 4 mg)

Critical NM protocol notes: 1. Never place a tourniquet around an affected extremity, except in the case of uncontrollable hemorrhage per Hemorrhage/Bleeding Guidelines 2. Rapid onset of signs and symptoms indicates a major envenomation — priority transport 3. Do not cut and attempt to remove poison 4. Do not use any type of cryotherapy on bite wound

NREMT Relevance

  • Scene safety first — never approach or handle the animal
  • Four prohibited actions: tourniquet, cut-and-suck, cryotherapy (ice), constriction band
  • Immobilize extremity at heart level
  • Anaphylaxis can co-occur — know the trigger for epinephrine (systemic involvement)
  • Antivenom is hospital-only — prehospital role is transport and supportive care
  • Mark swelling progression (pen + time) as a severity monitoring tool
  • scene-size-up — scene safety is the first priority; identify the animal type if visible
  • anaphylaxis — systemic allergic reaction to envenomation; epinephrine criteria
  • epinephrine-auto-injector — if anaphylaxis develops from envenomation
  • shock — severe envenomation can cause vasodilatory or distributive shock
  • primary-assessment — systemic signs may develop rapidly; priority decision
  • history-taking — time of bite, type of animal, symptom progression are critical

Sources

  • raw/protocols/nm-sop-guidelines-treatment-2022.pdf — Bites-Venomous protocol (p. 62–63)