The administration of antivenom is a critical treatment in the management of venomous snake and spider bites, as well as some marine animal stings. Antivenom is used to neutralize the venom’s harmful effects, and its administration is a specialized medical procedure. Here’s an overview of antivenom administration:
- Indications for Antivenom Use
- Snakebites: When there is evidence of envenomation, such as systemic symptoms (e.g., nausea, vomiting, abdominal pain, respiratory distress), neurotoxicity, coagulopathy, AKI, or significant local injury.
- Spider Bites: For example, in cases of severe redback spider or funnel-web spider bites.
- Other Envenomations: Certain marine stings (e.g., box jellyfish) or scorpion stings where specific antivenoms are available.
- Pre-Administration Assessment
- Identification of the Culprit: If possible, identify the species responsible for the envenomation to administer the correct antivenom. However, treatment should not be delayed if the species is unknown.
- Assessment of the Patient: Evaluate the patient’s symptoms, vital signs, and perform necessary laboratory tests (e.g., coagulation profile, kidney function tests).
- Allergy History: Check for a history of allergies, especially previous reactions to antivenom or horse serum, as many antivenoms are derived from horse serum.
- Administration Procedure
- Informed Consent: Explain the benefits and risks to the patient or their guardian.
- Pre-Medication: In some cases, pre-medication with antihistamines or corticosteroids may be considered to reduce the risk of allergic reactions.
- Route of Administration: Most antivenoms are administered intravenously.
- Dose: Follow the specific dosing guidelines for the type of antivenom being used. The dose may depend on the severity of the envenomation and the type of venomous animal.
- Slow Initial Administration: Begin with a small test dose to gauge any immediate hypersensitivity reactions. If no adverse reaction occurs, continue with the full dose.
- Monitoring: Monitor the patient closely for any signs of anaphylactic or allergic reactions. Have resuscitation equipment and medications on hand.
- Completion of Dose: Administer the entire dose as per guidelines, unless a severe reaction necessitates stopping the infusion.
- Post-Administration Monitoring: Continue to monitor the patient for several hours post-administration for signs of recurrent or ongoing envenomation, and for delayed hypersensitivity reactions.
- Management of Adverse Reactions
- Mild Allergic Reactions: May be managed with antihistamines or pausing the antivenom infusion.
- Anaphylaxis: Requires immediate cessation of the antivenom and the administration of adrenaline, oxygen, and other supportive measures.
- Post-Antivenom Care
- Observation: Patients should be observed in a medical facility for an extended period post-antivenom administration due to the risk of delayed reactions or recurrent envenomation.
- Laboratory Testing: Repeat laboratory tests to assess the effectiveness of the antivenom and monitor for complications.
- Special Considerations
- Australian Context: In Australia, antivenoms are available for several snakes (e.g., tiger snake, brown snake), the funnel-web spider, the box jellyfish, and others.
- Training and Protocol: Healthcare providers administering antivenom should be trained and familiar with the protocols, including managing potential adverse reactions.
In summary, the administration of antivenom is a lifesaving intervention in the management of serious envenomations. It requires careful patient assessment, adherence to protocols, readiness to manage allergic reactions, and close post-administration monitoring.