Bites and Stings ppt

Mammalian Bite Evaluation

• Assess time since injury and mechanism of injury, including direct bites or injuries sustained from punches.
• Evaluate the anatomic location, depth of penetration, and tetanus immunization status.
• Consider medications, allergies, and risk factors for infection.
• Vascular areas show lower infection rates than avascular, with dog bites having a lower infection risk compared to deeper-piercing cat bites.

Mammalian Bite Management

• Follow ABCs and consider cervical spine stabilization if necessary.
• Clean wounds with povidone-iodine and perform copious irrigation using normal saline.
• Evaluate for foreign bodies or underlying injuries using x-rays.
• Debride devitalized tissue, as flap avulsions may not heal effectively.
• Prophylactic antibiotics are prescribed or are used for treating active infections.
• Consider tetanus and rabies post-exposure protocols.
• Avoid suturing bite wounds to reduce infection risk, except for large wounds requiring stabilization.

Human Bites

• Human bites pose a high infection rate, up to 50%, especially in the hands and extremities.
• Specific injuries like “fight bites” can disrupt the MCP joint leading to severe infections.
• Males are more likely to sustain human bites; pathogens include Eikenella corrodens, common in human bite wounds.
• Prophylactic antibiotics are crucial; standard treatment includes amoxicillin clavulanate (Augmentin).

Dog & Cat Bites

• Approximately 3-6 million animal bites occur yearly in the U.S., with 85% being dog bites and 10% from cats.
• Dog bites usually result in crushing/tearing wounds, while cat bites are often puncture wounds, with a higher infection rate (66%).
• Cat-scratch disease includes regional lymphadenopathy developing 7-12 days after a cat bite.
• Common pathogens from animal bites include Pasteurella multocida and Bartonella henselae.

Insect Bites/Stings

• Hymenoptera insects (bees, wasps, hornets) can cause a range of reactions from mild to life-threatening.
• Monitor for rapid onset of symptoms, including pain, edema, and potential anaphylaxis.
• Management of anaphylaxis includes administering epinephrine and supportive medications.

Spider Bites

• Most spider bites are non-venomous; venomous bites include those from Black Widow and Brown Recluse.
• Black Widow envenomation causes neurotoxic effects like muscle cramps and systemic symptoms.
• Brown Recluse bites may lead to painful necrotic lesions; management includes analgesia and sometimes surgical intervention.

Snake Bites

• About 30,000 snake bites occur annually in the U.S., with 8,000 classified as venomous; most common are rattlesnakes and copperheads.
• Symptoms of venomous snake bites include fang marks, swelling, and possible systemic effects.
• Treatment includes removing constrictive clothing, monitoring for swelling, and administering antivenom for severe cases.
• Coagulation studies are critical to managing complications like coagulopathy or compartment syndrome following envenomation.

Rabies

• Rabies is nearly always fatal post-symptom onset, with domestic dogs being major carriers.
• Management includes wound washing, vaccination status assessment, and initiating rabies post-exposure prophylaxis.
• Rabies vaccine regimen requires doses on days 0, 3, 7, and 14, with rabies immune globulin (HRIG) for unvaccinated individuals.

Tetanus Considerations

• Always inquire about tetanus vaccination status for any bite, sting, or wound.
• Tetanus prophylaxis is required based on the type of wound and last immunization date.### Patient Discharge Guidelines
• Normal repeat laboratory tests may allow discharge within 24 hours for children, elderly, those with significant comorbidities, or poor social support.
• Asymptomatic patients with suspected Mojave rattlesnake bites may be observed for 12-24 hours due to potential delayed neurotoxicity.

Antivenoms

• ANTIVENIN: High-affinity antibody that enhances elimination of venom proteins.
• Wyeth Polyvalent Antivenin: Produced by immunizing horses with four pit viper venoms; effective against various snakes including rattlesnakes and South American bushmaster.
• Cost-effective at approximately $40 per vial.
• Dosing guidelines include:
  • Dry bite: No treatment required.
  • Minimal envenomation: 5 vials.
  • Moderate or severe envenomation: 10 and 15 vials respectively.
• CroFab: Monoclonal F(ab) fragments with a lower chance of allergic reactions, significantly more expensive (~$40,000 per dose).
• Initial dosing for CroFab involves 4-6 vials, followed by additional doses if required.

Complications of Antivenom Administration

• Risks include allergic reactions, anaphylaxis, and potential thrombocytopenia.
• Anaphylactic Shock is most common in patients with prior allergic reactions to substances like insects, food, or medications.

Signs and Symptoms of Anaphylaxis

• Skin and mucosal symptoms: Up to 90% of cases, including hives, swelling of lips/tongue/uvula.
• Respiratory symptoms: Present in about 70% of cases; symptoms can include nasal discharge, stridor, shortness of breath.
• Gastrointestinal symptoms: Occur in 45% of cases with nausea, vomiting, and abdominal pain.
• Cardiovascular symptoms: Included are hypotension, tachycardia, dizziness, and collapse.

Diagnostic Criteria for Anaphylaxis

• Criterion 1: Acute skin or mucosal symptoms with respiratory compromise or reduced blood pressure.
• Criterion 2: Rapid involvement of two or more organ systems after allergen exposure, including gastrointestinal symptoms.
• Criterion 3: Reduced blood pressure following exposure to a known allergen, with specific values for children.

Management Steps

• Immediate identification and removal of inciting causes of anaphylaxis is essential.
• Epinephrine administered via IM injection is the treatment of choice.
• Supplemental oxygen and volume resuscitation with IV fluids are critical components.

Medications in Anaphylaxis Management

• Steroids (e.g., solumedrol, dexamethasone) and H1 antihistamines (e.g., diphenhydramine, cetirizine) may relieve symptoms but do not replace epinephrine.
• Glucocorticoids have delayed onset; typical first dose is methylprednisolone 125 mg.

Airway Management

• Intubation is necessary if stridor or significant respiratory distress is noted.
• Prepare for emergency airway procedures like cricothyroidotomy if severe edema occurs.

Epinephrine Administration

• Route of choice is IM, with a recommended initial dose of 0.01 mg/kg (up to 0.5 mg).
• Auto-injector doses are 0.3 mg for adults and 0.15 mg for children.
• Repeat doses may be required every 5-15 minutes.

Fluid Management

• Administer 1-2 liters of normal saline for hypotensive patients; larger volumes may be necessary.
• Establish IV access for rapid fluid administration due to significant vascular permeability changes.

Additional Medications

• H1 antihistamines help with itch and hives but do not address airway obstruction or hypotension.
• Cetirizine is less sedating and available in both IV and oral forms.
• Glucocorticoids take hours to become effective but are an essential part of management.

This quiz covers the crucial aspects of evaluating and managing mammalian bites. It includes information on injury mechanisms, bite wound characteristics, and factors influencing infection risk. Understanding how to assess and treat these injuries is essential for effective medical care.