Terrestrial Bites and Stings
description
Transcript of Terrestrial Bites and Stings
Terrestrial Bites and Stings
Brian Costello, MD
Department of Pediatric Emergency Medicine
June 24, 2010
2
Objectives
By the end of this lecture you should be able to: Describe the management and treatment for
• Reptile envenomations• Arthropod envenomations• Mammalian bites and common associated
infections Understand and perform initial management of
these injuries, such as• Local wound care• Venom specific antidotes• Stinger and tick removal
3
Snakes
US has 120 different species of snakes• Only 15% poisonous
Two families:• Crotalidae (pit
vipers) 99% of snakebites
• Elapidae 1% of snakebites
4
Identifying Poisonous Snakes
5
Include Water Moccasin (aka Cottonmouth), Rattlesnake, and Copperhead
Venom is a combination of necrotizing, hemotoxic, neurotoxic, nephrotoxic and cardiotoxic substances
• Mojave rattlesnake has a large fraction of neurotoxin
• Neurotoxin prevents depolarizing action of acetylcholine (paralytic)
• Proteolytic enzyme acts like hyaluronidase causing local tissue destruction, swelling
• Increased capillary leak – shock, respiratory failure
• Hemotoxic effects include hemolysis, thrombocytopenia and fibrinogen proteolysis leading to bleeding diathesis
Crotalids
6
Crotalids
Small children are more susceptible to venom given their size compared to adults causing more systemic symptoms
Bites on the head, neck or trunk hasten systemic absorption
Most bites are on the extremities Measure the distance between the two fang marks
to estimate snake size• 8 mm = small snake• 8-12 mm = medium snake• >12 mm = large snake
10-20% of rattlesnake strikes are “dry” (no venom)
7
Crotalid Bites - Symptoms
5-10 min – Intense pain, erythema, and edema Perioral numbness with metallic taste N/V, chills, weakness, syncope, sweating Neuromuscular symptoms after a few hours:
• Diplopia, difficulty swallowing, lethargy, progressive weakness
Next 8 hours – Progressive edema at wound site Shock – usually 6-24 hrs (may be as soon as 1 hr) Vesicles and hemorrhagic blebs by 24 hours Edema may lead to compartment syndrome and
necrosis Secondary infection – gram-negative bacteria
8
Crotalid - Management
Pre-Hospital • ABCs• Rest• Take off jewelry and clothing from affected
extremity• Immobilize extremity and keep below level of
heart• Keep warm• NPO• Constriction band (experienced hands only)• Incision and Suction kit if available (must use
within 5-10 minutes of bite)• Rapid transport to medical facility
9
Snake Bite Kits
10
Crotalid - Management
ED• IV access, fluids, (central line & CVP?), morphine• If snake is brought to ED, treat it with respect
Many people bitten by “dead” snake Decapitated snakes bite reflexively for up to 1
hour• Measure circumference of extremity at leading
point of edema and 10 cm proximal Q30min X 6 hours, then Q4 for 24 hours
• CBC with platelets, coags, type and cross, U/A • If moderate or severe poisoning, then also get
BMP, fibrinogen and ABG• Repeat labs Q4-6 hours
11
Crotalid Antivenin
AVCP polyvalent antivenom• Horse serum, highly antigenic – needs skin
testing prior to giving• Don’t use it if you can get CroFAB
CroFAB• Sheep derived antibody with cleaved Fc portion
Cleared from kidneys fast• Less adverse reactions
For maximal binding, use antivenom within 4 hours of bite.
Dosage NOT based on weight. Kids need more.
12
Crotalid - Management
CroFAB• Initial dose is 4-6 vials• Repeat initial dose if there is progression of
symptoms• Once there is no progression, then give either:
2 vials Q6h for 3 doses OR 2-6 vials if progression of symptoms recur
• Admit to PICU• All patients must be reexamined in 2-5 days after
bite• Watch for serum sickness up to 3 weeks out
13
Crotalid - Management
Local wound care Tetanus prophylaxis NO ice to wound Watch for signs of compartment syndrome, call
surgery Superficial debridement needed in 3-6 days
• Local oxygen, aluminum acetate 1:20 solution, triple dye
Blood products for coagulopathy No prophylactic antibiotics (current thinking) Physical therapy in healing phase
14
Elapids
Only 3 poisonous Elapids in US:• Eastern Coral Snake –
Found in Georgia• Texas Coral Snake• Arizona Coral Snake• “Red on yellow, kill a
fellow; Red on black, venom lack”
15
Elapids
Coral snakes are relatively passive (10-15 bites/yr in US)
Share physical characteristics of non-venomous snakes (round pupils, blunt head) but have fangs
Uses a potent neurotoxin Local signs are minimal with little pain Several hours later, pt will develop malaise, N/V,
muscle fasiculations and weakness Neurologic signs include diplopia, difficulty talking
or swallowing, bulbar dysfunction, and generalized weakness
Risk of respiratory failure
16
Elapids - Management
Tourniquets, incision & suction, etc. don’t work for coral snakes
If eastern or Texas coral snake is suspected, give antivenin• Horse serum derived, requires skin testing before
giving• Dosage is 3-5 vials IV• Repeat if signs of venom toxicity continue• Antivenin not in production as of 2008
No antivenin available for Arizona coral snake Admit to PICU
17
Quiz: Name Georgia’s Venomous Snakes…
18
Georgia Venomous Snakes
Georgia Carolina Pygmy Rattlesnake - Sistrurus miliarius miliarius Dusky Pygmy Rattlesnake - Sistrurus miliarius barbouri Eastern Coral Snake - Micrurus fulvius Eastern Cottonmouth - Agkistrodon piscivorus piscivorus Eastern Diamondback Rattlesnake - Crotalus adamanteus Florida Cottonmouth - Agkistrodon piscivorus conanti Northern Copperhead - Agkistrodon contortrix mokasen Southern Copperhead - Agkistrodon contortrix contortrix Timber Rattlesnake - Crotalus horridus Western Cottonmouth - Agkistrodon piscivorus leucostoma
19
Exotic Snakes
Consult a medical herpetologist or poison control (1-800-222-1222)
Contact your local zoo• Required by law to carry antivenin for the snakes
they have Report illegally possessed reptiles to the police
20
Arthropods (“Bugs”)
Largest phylum in the animal kingdom Terrestrial Invertebrates
• Centipedes/Millipedes• Ticks• Spiders• Scorpions
Insects• Bees• Hornets• Yellow Jackets• Wasps• Fire Ants
21
Very few are dangerous to humans in North America• Centruroides sculpturatus (“Arizona bark
scorpion”) -- southwestern U.S. Grasps prey by pincers and then stings with tail Nocturnal
• Crawl into sleeping bags and unoccupied clothing
Injects an excitatory neurotoxin affecting autonomic and skeletal nervous systems -minimal local edema• Pain, restlessness, hyperactivity, roving eye
movements, respiratory distress/failure• Convulsions, drooling, hyperthermia,
HTN/tachycardia
Scorpions
22
Scorpions - Management
Cryotherapy (ice) at sting site and supportive care Antivenin if symptoms persist after supportive care
• Tachycardia• Fever• Severe hypertension• Agitation• Available from Antivenom Production Laboratory,
Arizona State University, Tempe, Az. Phenobarbital or other sedative/anticonvulsants for
persistent hyperactivity, convulsions or agitation Calcium gluconate 10% 0.1ml/kg for muscle
contractions (used but unproven)
23
Brown Recluse Spider (Loxosceles)
Brown violin shaped mark on dorsum of cephalothorax (“Fiddleback”)
Usually outdoors, but make indoor nests in closets
Shy and will only attack when provoked
Venom is cytotoxic (hyaluronidase-like factor)
Loxosceles reclusa
24
Loxosceles Geographic Distribution
25
2-8 hours• Local reaction with mild-moderate pain• Erythema, central blister or pustule
24 hours• Fever, chills, malaise weakness, N/V, rash with
petechiae, joint pain, DIC, hematuria, renal failure, hemolysis, respiratory failure
• Subcutaneous discoloration that spreads over 3-4 days
• Spreads to 10-15 cm• Pustule drains leaving ulcerated crater that scars
Scar formation is rare if no necrosis after 72 hrs Reaction varies according to amount of
envenomation
Brown Recluse – Clinical Signs
26
Brown Recluse Bite Mimics in Children
Staph/strep (MRSA) Herpes simplex Herpes zoster E. multiforme Lyme disease Fungal infection P. gangrenosum Chemical burn Poison ivy/oak
Other spider bite:1.Golden orb weaver (North
America)
2.Running (or sac) spider (U.S.)
3.Wolf spider (U.S.)
4.Black jumping spider (Atlantic coast to Rocky Mountains)
5.Hobo spider (Pacific Northwest)
6.Fishing spider (U.S.—lakes and streams)
7.Green lynx spider (Southern U.S.)
27
28
It’s NOT a brown recluse if…
It's really BIG! The size of the body, not including legs, of a recluse is smaller than a dime.
It's really HAIRY! Brown recluses have only very fine hairs that are invisible to the naked eye.
It JUMPS! Jumping spiders live up to their name, and some other spiders including wolf spiders occasionally jump, but recluses don't.
I found it in a WEB! Brown recluses don't spin a web to catch prey; they spin silk retreats and egg cases, but don't form a typical recognizable web.
It has DISTINCT MARKINGS VISIBLE TO THE NAKED EYE, such as stripes, diamonds, chevrons, spots, etc. that are easily seen! The "violin" is very small and located on the front half of the body. The violin is also indistinct in some, especially young spiders. They're really pretty dull looking.
http://department.monm.edu/biology/recluse-project/identify.htm
29
Quiz: Indentify 2 Brown Recluses…
30
Brown Recluse - Management
Unless spider is brought for ID, definitive diagnosis cannot be made
Good local wound care If systemic symptoms, then CBC with platelets,
U/A, BUN, creatinine• Vigorous supportive care in PICU as needed
Surgical excision and (rarely) skin grafting after necrosis is demarcated
Steroids, heparin, and hyperbaric O2 don’t work
No Dapsone for kids – methemoglobinemia No antivenom available Have wound rechecked daily for progression
31
Black Widow (Latrodectus)
Shiny black spider with brilliant red hourglass marking on abdomen
Only the female bite is dangerous• Male spiders are ¼ the size of
females and bite cannot penetrate human skin
Females not aggressive unless provoked or guarding egg sac
Produces a neurotoxin—stimulates myoneuronal junctions, nerves, nerve endings
Latrodectus mactans
32
No local symptoms 1-8 hours after bite
• Generalized pain and muscle rigidity Cramping pain to abdomen, flanks, thighs,
chest – “rigid abdomen”• Chills, N/V• HTN, Tachycardia• Respiratory distress• Urinary retention• Priapism• Death from cardiovascular collapse
Mortality 50% in young children
Black Widow – Clinical Signs
33
Black Widow - Management
Children < 40kg: Antivenin given as soon as bite confirmed• Dose: 2.5ml (one vial)
Children >40kg: not as urgent to give immediately; indicated in age <16, respiratory difficulty, significant hypertension
Morphine or Demerol Calcium gluconate 10% solution 0.1ml/kg IV over 5
minutes for muscle cramps• Recent series showed effective in only 4% of
cases• Valium can be used, but is short lived with
variable effects; Robaxin is ineffective Admit to PICU
34
Other Spiders
Tarantulas• Do not bite unless provoked• Venom is mild and not a problem
Wolf Spider and Jumping spider• Mild venom only causes local reaction
Treatment is good local wound care
35
Centipede/Millipede
Centipedes• Bites with jaws that act like stinging pincers• Extremely painful• Toxin is innocuous – local reaction only
Millipedes - harmless Treatment
• Local anesthetic at wound site• Local wound care
36
Ticks
Transmit many other infectious diseases:• Spirochetes – Lyme Disease, relapsing fever• Viruses – Colorado tick fever• Rickettsiae – Rocky Mountain spotted fever• Bacteria – tularemia, ehrlichiosis, babesiosis• Protozoa
Tick paralysis – wood tick, dog tick, deer tick• Tick releases neurotoxin producing cerebellar
dysfunction and ASCENDING Weakness• Latent period for 4-7 days• Restlessness, irritability, ascending flaccid
paralysis, respiratory paralysis, death
37
Tick Paralysis - Management
Diligently search for the tick Remove using blunt forceps held close to skin Do not squeeze – can release infective agents Admit to hospital for ascending paralysis, PICU if
worried about respiration
38
Bees have a barbed stinger next to a venom sac which can remain in the victim’s skin
Bees die after the stinger is dislodged
The stinger must be removed if seen – don’t delay, move venom is released with time• Scraping works best, don’t pull
or squeeze Wasps, Yellow Jackets, and
Hornets can sting multiple times
Bees, Hornets, Yellow Jackets, & Wasps
39
Insects
Venoms contain protein antigens which elicit an IgE antibody response
Major problem is allergic reactions and anaphylaxis• Group I – local response• Group II – Mild systemic reactions
Generalized itching and urticaria• Group III – Severe systemic reactions
Wheezing, angioneurotic edema, N/V• Group IV – Life threatening reactions
Laryngoedema, hypotension, shock Occurs in 0.5-5% of the population from insects
40
Insect - Management
Group I – cold compresses Group II – Benadryl 4-5 mg/kg/day divided QID Group III
• Epinephrine 1:1000 0.01 ml SQ (max 0.3ml) (IM?)
• Benadryl PO
• H2 blockers
• Steroids (?)• Admit to hospital for 23 hr obs
41
Insects - Management
Group IV – may need intubation• All of the above, plus• Wheezing refractory to epinephrine may need
aminophylline 6mg/kg bolus over 20 minutes, then 1.1 mg/kg/hr infusion
• Hypotension Fluid bolus IV epinephrine 1:10,000 IV Hydrocortisone 2mg/kg Q6h
• Admit to PICU
42
Insects - Management
Group III or IV reactions need referral to an allergist for hyposensitization
After obs, D/C home with EpiPen Jr.• Spring loaded autoinjectors self-administered in
the thigh• Always write for the twin pack
Contains practice syringe and 2 loaded syringes
• Parents should give this in the field AND seek further care
Avoid wearing bright colored clothing, perfumes Wear long sleeved garments, gloves when
gardening and hats Medical alert bracelets or necklaces
43
Fire Ants
Wingless member of Hymenoptera
Bites with jaws and pivots head to give multiple stings
Venom is an alkaloid with direct effect on mast cell membranes
Solenopsis richteri and Solenopsis invicta
44
Red Imported Fire Ant (RIFA)
Arrived in 1930s from South America via port of Mobile, Ala.
Build mounds in sunny, open areas (e.g., lawns and parks)
Aggressively attack anyone who disrupts their mound
45
Fire Ants – Clinical Presentation
Immediate – wheal and flare
4 hrs – vesicle 8-10 hours – vesicle
becomes umbilicated pustule
24 hrs – vesicle surrounded by painful erythematous area that lasts 3-10 days
46
Fire Ants - Treatment
Symptomatic care• Ice• Cleansing• Antihistamines for itching• Steroids, antibiotics and antihistamines don’t
have an effect on the lesions Occasional systemic reactions (hives, anaphylaxis)
47
Mammalian Bites
Dog bites account for 80-90% of all mammal bites Cats 5-10% Rodents 2-3% Humans 2-3% Other wild or domestic animals make up the rest
48
Mammal Bites
Dogs generate strong forces and cause local crush injuries
Only 5-10% of bites become infected because wound is easily cared for and not very deep
Cat bites cause deep puncture wounds with 50% infection rate• May penetrate fascial compartments, tendons,
vessels and bones Most common bacteria: Staphylococcus &
Pasturella species Human bites are Strep viridans or Staph aureus Also many anaerobes are mixed in: Bacteroides,
Peptostreptococcus, Eikenella corrodens
49
Dog Bites
Usually attack head and neck in most victims Cause lacerations of lips, nose and cheek May penetrate the skull and cause depressed skull
fracture
50
Cat Bites
Usually attack upper extremities Pasturella infections are very aggressive
• Symptoms begin at 12-24 hours with erythema, significant edema and intense pain
Cats also scratch, especially the face Consider corneal abrasions Bartonella henselae
• Papule at site of scratch with later regional lymphadenopathy
• Self limited, resolves in 2-3 months• May have unusual manifestations:
encephalopathy, hepatitis, atypical pneumonia
51
Typically involve the hand when punching someone in the mouth• Wound overlies the MCP joint, consider Boxer’s
fracture• Mild swelling in 1-2 days to site• If there is pain with active or passive finger
motion, then consider tendonitis or deep compartment infection
• Also consider Hepatitis B and syphilis being spread by bites
Human Bites
52
Rodent Bites and Other Mammals
Rat-bite fever (rare) Pet owners and lab workers
• 2 forms: Haverhill fever (Streptobacillus moniliformis) Sodoku (spirullum minus)
• 1-3 week incubation period• Chills, fever, malaise, rash, headache• Both forms responsive to IV penicillin
Rabbits – tularemia
53
Mammal Bites - Treatment
Meticulous and prompt wound care• Scrubbing with soft sponge and 1% povidone-
iodine solution Stronger solutions retard wound healing
• Pressure irrigation Facial wounds require primary closure for cosmesis Hand wounds should have delayed primary closure
or heal by secondary intention due to infection rate• Place a few deep sutures to bring wound
together• Skin sutures placed in 3-5 days
54
Mammal Bites - Treatment
Antibiotic prophylaxis• No perfect drug, but Augmentin is close• If allergic, then a combination of clindamycin
PLUS a 2nd or 3rd gen cephalosporin OR Bactrim• First dose should be given in the ED
Infected bites require aggressive drainage and debridement• Obtain aerobic and anaerobic deep would
cultures• Leading edge would culture for cellulitis• Admit for IV antibiotics
Tetanus prophylaxis
55
Rabies
Rabies virus• Virus transmitted through scratches, abrasions
and animal saliva contact with mucous membranes
• Causes an progressive, irreversible encephalopathy traveling up peripheral nerves to the brain Anxiety, insomnia, confusion, agitation,
hypersalivation, hydrophobia• Unprovoked attacks• Wild carnivorous animals, BATS• Rodents, squirrels and rabbits are considered
no-risk
56
Rabies
If the animal can be observed, then prophylaxis can be delayed
If the animal shows signs of rabid behavior, then start the patient on prophylaxis immediately• Animal will be sacrificed and brain biopsy will be
done to look for rabies Prophylaxis is with passive antibody (RIG) and
vaccine HDCV• RIG is given once, half IM and the other half
infiltrated around bite• HDVC is given 1.0 ml IM on days 0,3,7,14
(Reduced 4-dose vaccine schedule as of 2010)
57
Questions?