Venomous animals
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Venomous animals Document Transcript

  • 1. VENOMOUS ANIMALSINTRODUCTION Fatalities: insects 50%, snakes 30%, spiders 13% Bees are the MCC of fatal venomous animal injuries Black widow is the MCC of spider related death Poisonous animal = animal contains toxin, may become toxic by eating Venomous animal = animal has a specific gland for producing the toxic venom which is connected to an apparatus for delivering the venom to another animal Toxicity is highly variable even with the same kind of snake: depends on degree of envenomation Many snake bites DO NOT result in envenomation (30-50%) Toxicity: local pain, burning -------------> DIC, shock, ARDS, MSOF, death Anaphylactoid reaction can also occur SNAKESINTRODUCTION Five families of venomous snakes  Crotalidae (pit vipers): rattlesnakes, water moccasins, copper heads  Colubridae: bird snake, boomslang  Hydrophidae: sea snakes  Elapidae: cobras, coral snakes, etc  Viperidae (true vipers): Russell’s viper, puff adder, etc Identifiication  Only experts should handle snakes; dead snakes can still envenomate  Pit Vipers: pit between eye and nostril on both sides of head which is a heat- sensitive organ to locate warm-blooded prey; presence of the pit is 100% accurate; other features include elliptic pupil, triangular shaped head, and presence of fangs but these are less uniform Toxins  Toxins have variable toxicity  Hosts have variable responses to the same toxin  Venoms are neurotoxic and hematotoxic  Can be classified s protein and non-protein components  Protein components: enzymes and polypeptides  Enzymes: coagulation, anticoagulation, cell lysis, hemorrhage, hemolysis, destruction of nucleic acids  Polypeptides: neurotoxins, cardiotoxins, etc  Phospholipase A: enzyme that inhibits the electron transport chain at cytochrome C, inhibits neurve axons,, leads to destruction of Ach at nerve terminals, causes hemolysis: this enzyme has been identified in the venom of all venomous snakes Venom Delivery  Two venom glands, hollow or grooved fangs, ducts connecting the fangs to the venom gland which are evolved from salivary glands  Venom glands have nerve supply to allow the control of the gland  The snake can control the amount of venom that is injected
  • 2. RATTLESNAKE BITESLOCAL TOXICITY Immediate burning, pain, erythema, edema Petechiae, ecchymosis, hemorrhagic bullae, necrosis Severity of local symptoms/signs related to amount of venom injected Compartment syndromes from massive edema has occurred Local infections are a later concern Tetanus, osteomyelitis, cellulitis, gangrene can occurSYSTEMIC TOXICITY Systemic symptoms: weakness, nausea, fever, vomiting, sweating, metallic taste in mouth, fasiculations, hypotension, SOB, chest pain Death results form disruption of coagulation system and increased capillary lead ARDS, shock, DIC, ARF, hepatic failure, MSOFPREHOSPITAL CARE Remove patient from environment Calm the patient and immobilize the limb: movement increases the spread of venom Place a constricting band above the bite: tight enough to stop venous flow only  Immobilization and Compression technique: wrap the bitten extremity in an elastic bandage or place in an air splint ----> technique used in Australia  Monash method: thick pad and bandage over the bite wound and extremity ----> another technique used in Australia Suction the wound if the bite occurred < 15 minutes ago Apply ice bag wrapped in a towel: decreases pain but does not decrease spread of venom (do NOT immerse in ice water or pack the extremity in ice b/c of increased tissue destruction) Identify the snake and bring to hospital if possible NPO, NO etoh Cardiac monitor, establish iv accessED ASSESSMENT Important historical features  Time since bite  Circumstances around bite  First aid provided  Location of bite(s)  Local and systemic symptoms  PMHx, tetanus, meds  ALLERGY: ? horses, ? previous serum injections, hay fever, urticaria (all increase the risk of reaction to antivenin Important physical exam features  Look for signs of envenomation: edema, petechiae, ecchymosis, bullae  Check distal neurovasc supply  Check for signs of compartment syndrome  General exam
  • 3. ED MANAGEMENT General  First aid maneuvers if not done in field and still applicable  ECG monitoring, iv access  Labs: cbc, lytes, creat, coags, liver enzymes, fibrinogen, crossmatch for 2 units, CK and urine for myogloin  Tetanus, Ancef prophylaxis, Fasciotomies prn Grading of Envenomation  Grade 0 - No evidence of envenomation - Fang wound may be present - Minimal pain - Minimal edema (< 2cm) - Minimal erythema - No systemic symptoms within 12hrs - No antivenom neccessary  Grade I - No envenomation - Fang wounds preent - Moderate pain or throbbing - Edema/erythema 1-10 cm around bite - No systemic symptoms w/i 12hrs - No lab changes - No antivenom necessary  Grade II - Moderate envenomation - More severe pain - Edema, erythema spreading toward the trunk - Petechieae and ecchymosis limited to the area of bite - Systemic symptoms of N/V and mild temp - 5 vials of antivenom  Grade III - Severe envenomation - May initially look to be grade I or II but progresses rapidly within the first 12 hours - Edema spreads to the trunk - Generarlized petechieae and echhymosis - Tachycardia, hypotension, hypothermia - 10 vials of antivenom  Grade IV - Very severe envenomation - Sudden, severe pain with rapid progression of swelling, ecchymoses, bleb formation, and necrosis - Systemic symptoms within 15 min of bite: weakness, N/V, vertigo, numbness of face, fasiculations, cramping, pallor, sweating, tachycardia, hypotension, seizures, decreasing LOC - 15 vials of antivenom
  • 4.  Skin Testing  Must be done regardless of history  Negative skin test decreases chance of reaction but they are still possible  Skin test may ppt bad reaction  0.02 ml o 1:1000 solution  Positive reactions occur within 5-30min: edema around the wheal Dosing and precautions  ANTIVENOM is the only proven therapy  Be ready for anaphylaxis  Children’s dose is relatively more than adults  Pregnancy is not a contraindication  Do not administer near the bite  Repeat doses q1-2 hours prn  5-15 vials iv, 1:10 dilution  Gravol and steroids for serum sickness Crofab  Fewer allergic reactions  Developed from sheep Disposition  Sick: admit to ICU  Asymptomatic: observe 4-6hrs  Local symptoms: observe 12 hours for progression, d/c if no progression VENOMOUS ARTHROPODSINTRODUCTION Arthropods = animals with segmented bodies and jointed appendages Two classes of interest: Insecta and Arachnida More deaths than snakes Most deaths from allergic response to venom rather than venom itself Three mechanisms: stinging, bitting, secreting venom through pores or hairsHYMENOPTERA Bees, ants, wasps, hornets, yellow jackets, ants Most sting but some bite and sting Bee: ovipositors protrude from adbomen with barbed stinging apparatus; bee dies with sting Wasp: unbarbed stinger, stings without hurting the wasp Phospholipase A and hyaluronidase are the most common enzymes Many antigens exist that account for the induction of allergy and anaphylaxis Sting to the lip, mouth, or tongue has high risk of airway obstruction Honeybee venom causes much more histamine release than other hymenoptera venom There is little antigenic overlap b/w species thus variability in reaction to stings Local effects: immediate pain, swelling, redness, ithcing Allergic symptoms: SOB, urticaria, wheezing, throat swelling, cough, resp arrrest Killer Bees  Aggressive bee from Africa and Brazil  Attach humans or cattle in clouds of bees
  • 5.  Fire Ants  Small, light - reddish born to dark brown ant  Venom is unique in that it is 90% alkaloid  Toxic venoum  Sting produced by a bite  Sterile pustule develops at site of bite  Local symptoms common  Allergic reaction in 10% Managment  Ice bag to sting to relieve pain  Anaphylaxis: iv fluids, benadryl, epi, steroids, ventolin, atrovent, nebulized epi, ranitidine  NO specific antivenom for hymenoptera stings  Benadryl q6hr X 24hrs  Uritcarial rash only: subQ epi + gravol + ranitidine and observe to r/o progression  Allergic reactions: prescribe EPIPEN and refer to allergist for testing and/or desensitizationBLACK WIDOW SPIDERS (Latrodectus mactans) General  Found throughout southern Canada  Female is twice the size of the male  Only the female is venomous  Glossy black, bright - red marking on abdomen (“black and red widow”)  Red marking may look like an hour glass or only two dots  Spider is about 3cm long  Found in protected spaces: under rocks, woodpiles, etc  Female can be aggressive when guarding eggs  Adults: symptomatic for days, usually not lethal  Children: higher risk of death!  Complex venom with protein and nonprotein compounds  Venom normally used to paralyze prey and liquefy tissues for digestion  NEUROTOXIN - is the most toxic component of the venom - more toxic than pit viper venom - destabilizes neuronal membranes by opening ion channels, causing depletion of Ach from presynaptic nerve terminals and increasing the frequency of spontaneous end plate potentials at the NMJ - MASSIVE release of Ach and norepinephrine Clinical Features  Initial pinprick sensation followed by minimal swelling, edema, redness  Two small fang marks may be visible  The bit may not initially be felt  15-60min: dull cramping pain in the area of the bite that spreads over the body  Hypertonic Myopathic Syndrome - Muscle cramps typically present 13-60 min after bite - Initially muscle cramps occur at the site of the bite
  • 6. - Progresses to the chest with UE bites and abdomen with LE bites - Abdomen may become rigid: may mimic an acute abdomen in rigidity but usually is not that tender  Faces Latrodectismia - Sweating, contorted, grimaced face associated with blepharitis, conjunctivits, rhinitis, cheilitis, trismus of the masseters  General - N/V, headache, SOB, pruritis, sweating, weakness, restless, difficulty speaking, ptosis, dizziness, diffuse cramping - Hypertension - ECG changes SIMILAR TO DIG TOXICITY  Life-Threatening Complications - Hypertensive crisis: 30% (due to norepi release) - Respiratory arrest secondary to respiratory muscle paralysis - Seizures secondary to neuronal activation Management  Ice pack to area for pain relief  Bring spider if possible!  Clean wound with soap and water  Administer tetanus booster prn  Opiods and benzodiazepines for pain control  Asymptomatic and NOT a black widow: d/c home, RTED instructions  Nitroprusside for hypertensive crisis  Symptomatic: admit to hospital  Draw cbc, lytes, coages, calcium  Calcium Gluconate - 10 ml of 10% solution iv over 20 min - Repeat dose prn q2-4 hrs - Cardiac monitoring, follow Ca+ levels - Traditionally used to decrease cramping - Mechanism of action unknown to decrease cramping - Some evidence that it makes things WORSE - NOT recommended by Goldfranks  Lorazepam/Morphine - Treatment of choice for pain control from muscle spasms  Lacrodectus Antivenom - <12yo or > 65yo or pregnant are at highest risk of mortality and may benefit from antivenom - Can be used in other ages depending on systemic toxicity - Any patient with severe envenomation should be considered - One vial diluted n 50 ml of normal saline over 15 min - TEST for sensitivity as per snake venom testing - Venom is derived inn horses
  • 7. BLACK WIDOW BOX Found in Southern Canada Black spider with Red abdomen Neurotoxin: Ach and NE release Severe muscle cramping Resp arrest, seizures Hypertensive crisis Local Mx: clean wound, td Mx: opiods and bzd for pain control CALCIUM CONTROVERSIAL Antivenom for young, old, pregnant, sickBROWN-RECLUSE SPIDER General  Several deaths have occured  Many different species  Identifying feature is the violin-shaped darker area found on the cephalothorax  No aggressive, mostly in southern US  Sphingomyelinase D is the primary component of the venom Clinical Features  Local: pain, swelling etc w/i a few hours, bleb forms in the center of an erythematous ring -------> resembles a BULL’S EYE  The BLEB darkens as tissue necrosis occurs and continues to spread to skin and subcutaneous fat  Systemic Management  Wash wound  Tetanus prophylaxis  Do NOT excise the lesion  Monitor vitals, cardiac monitor  Send labs, lytes, coags  Observe for envenomation: d/c after 6hrs if well  Dapsone - 50-200 mg/day - Helpful in preventing the local effects of the venom - Risk of methemoglobinemia and hemolysis with G6PD def  Other - HBOT to decrease tissue toxicity has been used - Dialysis has been needed for ARF - Antivenom not readily availableSCORPIONS Toxicity varies greatly between species Less dangersous produce more local symptoms More dangerous produce more sytemic symptoms Hemolytic enzymes and proteins in venom Severe immediate pain at site of sting
  • 8.  Systemic symptoms: SOB, CP, sweating, muscle spasms, syncope, N/V, HTN Cardiac arrythmias or respiratory arrest Children are at higher risk of death Management  Ice bag to area  Transport to ED  ANTIVENOM for all severe envenomations  Benzos for myoclonus and muscle spasmsOTHER ARTHROPODS Ticks: wood tick and dog ticks can also have a toxin that leads to ascending paralysis = TICK PARALYSIS Beetles and caterpillares: irritating substances which can cause local symptoms, was area with soap and wate, ice to area