Anaphylaxis and Bites Flashcards
Define anaphylaxis
- Life threatening systemic hypersensitivity reaction to contact w/ allergen
- May appear w/in minutes of exposure to offending allergen
How does anaphylaxis manifest?
- Respiratory distress
- Pruritis
- Urticaria
- Mucus membrane swelling
- GI disturbances (N/V/D/pain)
- Vascular collapse
What is the pathophys of anaphylaxis?
- Anaphylaxis requires prior sensitization or exposure to a specific antigen
- On re-exposure IgM & IgG Ab recognize the antigen as foreign & bind to it
- Ag presence activates IgE on basophils -> promotes release of mediators
How is histamine involved in anaphylaxis?
- Sudden release of histamine
2, Vasodilation & ↑ capillary permeability - Fluids leak into alveoli
How are Prostaglandins, bradykinin, serotonin
involved in anaphylaxis?
- Spread through body triggering systemic responses
2. Vasodilation, smooth muscle contraction, ↑ mucus production, ↑ capillary permeability
What are the most common allergens that cause anaphylaxis?
- Pollen extracts
- Serum
A. Immunizations - Venom
A. Bee venom - Foods
A. Nuts, berries, seafood - Drugs
A. Antibiotics, ASA - Radiographic contrast dye
What are the respiratory manifestations of anaphylaxis?
- Mucus membrane swelling
- Hoarseness
- Stridor
- Wheezing
What are the cv manifestations of anaphylaxis?
- Tachycardia
2. Hypotension
What are the cutaneous manifestations of anaphylaxis?
- Pruritis
- Urticaria
- Angioedema
How is anaphylaxis diagnosed?
- Anaphylaxis is a clinical diagnosis
A. Signs
B. Symptoms
C. Allergen exposure
How is anaphylaxis treated?
- Remove known Ag
- Epinephrine ASAP
- Beta agonist aerosol
- Oxygen
- Histamine 1 and 2 receptor blockade
- Corticosteroids
How is epi dosed for anaphylaxis?
- 0.3 – 0.5 of 1:1000 SC or IM
- Repeat dose q 5-20 min prn
- Life threatening sx’s
A. 2.5 ml of 1:10,000 solution IV slowly
B. IV NS fluid resuscitation
C. Vasopressor agents (Dopamine)
What beta agonist aerosols are used for anaphylaxis?
Albuterol 1 UD via nebulizer; repeat up to 3 Tx back to back
How is oxygen dosed for anaphylaxis?
Titrate to maintain SaO2 ≥ 95%
What histamine 1 and 2 receptor blockade agents are used for anaphylaxis?
- Diphenhydramine 50-100 mg IM or IV
2. Ranitidine 50 mg IV
How can anaphylaxis be prevented?
- Skin testing
- Avoid offending agent
- Desensitization
- Medic Alert bracelet
- Epi-pen
What is a normal reaction to an insect sting?
Pain, swelling, & redness around the sting site
What is a large local rxn to an insect sting?
Pain, swelling, & redness around the sting site and swelling extending beyond the sting site
What is a toxic rxn to multiple stings?
- Toxic reaction can occur if multiple stings (50+)
A. Hemolysis, rhabdomyolysis, renal failure, DIC, liver dysfunction
What are the sxs of a bee sting allergy?
- Difficulty breathing
- Hives or flushed or pale skin that spreads to areas beyond the sting
- Swelling of the face, throat, or tongue
- Wheezing or difficulty swallowing
- Restlessness & anxiety
- Rapid pulse
- Dizziness or a sharp drop in BP
- Nausea, vomiting or diarrhea
- Loss of consciousness
How is a bee sting (w/o allergy) treated?
- Sac of venom & stinger left inskin
- Remove stinger w/in 30 sec to avoid receiving more venom
- If stung on hand, remove rings immediately
- Wash area w/ soap & water, then apply an antiseptic
- Elevate extremity
- Ice
- Diphenhydramine prn
How is a bee sting allergy treated?
- Epinephrine 0.3 mg (EpiPen) SQ & diphenhydramine PO
A. Usually prevents more severe allergic reaction - Transport to ER
A. Observe for recurrent reaction - If anaphylaxis:
A. Repeat Epinephrine SQ
B. Oxygen
C. IV corticosteroid
D. Albuterol UD via nebulizer, repeat prn - Consider allergy testing & immunotherapy
What is the general information regarding eastern equine encephalitis?
- Virus spread by mosquitoes
- Cases found in MA & NH
- Fatality rate in humans is 33%
- Currently no cure for human infections
- 4& of infected humans develop symptoms
A. 6 cases/yr in the US
B. 1/3 of cases develop permanent brain damage
What are the sxs for EEE?
1. 3-10 day incubation period A. High fever B. Muscle pain C. Altered mental status D. Headache E. Meningeal irritation F. Photophobia G. Seizures
How is EEE treated?
- Corticosteroids
- Anticonvulsants
- Supportive measures
A. IV fluids
B. Intubation
C. Antipyretics
What is the habitat of the brown recluse spider?
- Most common in central US
A. Missouri, Kansas, Arkansas, Louisiana, eastern Texas, & Oklahoma - Lives in dark, sheltered areas
A. Under porches, basements, closets, woodpiles
What is the timeline for pain and rxn after a brown recluse bite?
- Pain develops 1-4 hr after bite, & may ↑ in severity
- Bite progresses from pustule → bull’s eye lesion → ulcer
A. Erythematous indurated localized swelling w/ necrotic central area
What are the effects of a brown recluse spider bite?
- Venom is cytotoxic
A. Causes local tissue destruction & hemolysis
What are the common sxs 1-4 days after a brown recluse spider bite?
- Reddish or purplish color around bite (Bull’s eye)
- Necrotic ulcer
- Fever
- Lymphadenopathy
What are the systemic sxs 24-48 hrs after a brown recluse spider bite?
- Arthralgias
- Malaise
- Fever
- Rash
- Nausea
What are the rare sxs after a brown recluse spider bite?
- Coma
- Blood in urine
- Jaundice
- Kidney failure
- Seizures
How is a brown recluse spider bite treated?
1. ER A. Elisa assay if spider not ID’d 2. Clean with soap & water 3. Bacitracin/Neosporin 4. Immobilize affected limb 5. Rx meds prn x 1 week A. Analgesic (Codeine or Tramadol) B. NSAID C. Muscle relaxer D. Antihistamine prn E. +/- Prophylactic Abx F. Dapsone (diaminodiphenyl sulfone) 6. Ice/Elevation 7. Tetanus if > 10 yr 8. May require debridement A. Wet to dry dressings or grafting
What is the prognosis for a brown recluse spider bite?
- Deaths from brown recluse spider bites are more common in children
- With proper Tx, survival past 48 hrs has good prognosis
- Ulcer may take up to 6 weeks to heal
Where are black widow spiders most common?
- Common in CA
2. Neurotoxic venom
What are the early (10-60mins) sxs of a black widow spider bite?
A. Severe pain at site B. Core muscle spasms C. Diffuse paresthesias D. Muscle fasciculations E. Piloerection F. Diaphoresis
When do sxs peak after a black widow spider bite and what are they?
1. Sx’s peak at 2-3 hr & last up to 7 days A. Headache B. N/V C. Ptosis D. Hyperactive DTR’s E. Severe pain F. Rigid abdominal muscles G. Severe HTN H. Tachycardia I. Death rare, but occurs infants and elderly w/ CVD
What is the tx for a black widow spider bite?
- ER observation x 12-24 hr
- Narcotic analgesics
- Calcium gluconate for pain
- Loose compression dressing
- Immobilization
- Ice if needed
- IV Antivenom in seriously ill infants & elderly
- Must test for horse serum sensitivity 1st
- High risk for allergic reaction/anaphylaxis
When should a pt bitten by a black widow spider be admitted to the hospital?
- Admit if:
A. 65yr
B. Hx of HTN
C. Severe sx’s
What are the common pathogens in a cat bite?
- Pasteurella multocida
2. Staph aureus
How is a cat bite treated?
- Wound care
- Amoxicillin/clavulanate
(cefuroxime, doxycyline or fluoroquinolone if PCN allergic) - Rabies IgG / vaccine if stray cat
- Tetanus if > 10 yr
What are the common aerobes in dog bites?
- Pasteurella multocida
- Pasteurella canis
- Staph aureus
- Streptococcus
- Capnocytophaga canimorsus (Gm neg. rod) oral flora
What are the common anaerobes in dog bites?
- Porphyromonas
- Bacteroides
- Fusobacterium
How are dog bites treated?
- Amoxicillin/clavulanate
- 3rd gen. cephalosporin
A. Cefdinir
B. Cefotaxime
C. Ceftriaxone - Fluoroquinolone or doxycycline if PCN allergy
- Tetanus if > 10 yr
- Loose or no closure
- X-ray to R/O Fx
- NSAID, ice for crush injury
- Elevate extremity
- 10 day observation of dog for rabies
A. Rabies IgG / vaccine if indicated
What percentage of snake bites are venomous?
25%
What are the 2 venomous types of snakes in the US?
- Veripidae
A. Hemotoxic (cytolytic) venom
B. Shreds RBC’s & vessels/severe pain
C. Rattlesnake, water moccasin, copperhead - Elapidae
A. Neurotoxic venom
B. Paralyze respiratory system
C. Coral snake
What are the local sxs of a bite from a viperidae snake?
- Edema
- Wound necrosis
- Hemorrhage
What are the systemic sxs of a bite from a viperidae snake?
- Hemolysis
- Thrombocytopenia
- Coagulopathy
- Vomiting
What is the treatment of a bite from a viperidae snake?
- ABC’s
- Immobilize limb
- ICU observation x 8+ hr
- Antivenom
A. IV CroFab - +/- Abx
What are the sxs of a bite from an elapid snake?
- Paresthesias
- Blurred vision
- Dysphagia
- Hypersalivation
- Ptosis
- Respiratory depression
What are the treatment options of a bite from an elapid snake?
- ABC’s
- Immobilize limb
- ICU observation x 8+ hr
- IV Antivenom
- +/- Abx
How are human bites treated?
Augmentin
Tetanus if > 10 yr
Loose or no closure
X-ray to R/O Fx