Extravasation is the accidental leakage of a vesicant substance from a vein into the surrounding tissue. In the case of vasopressors, which are used to increase blood pressure, this leakage causes intense local vasoconstriction, which starves the tissue of oxygen and can lead to severe injury, including blistering, necrosis, and potentially amputation. Phentolamine mesylate is a fast-acting, non-selective alpha-adrenergic blocker that reverses this vasoconstriction, restoring blood flow and preventing or minimizing tissue damage. The following protocol outlines the steps for administering this critical antidote.
Initial Emergency Response to Extravasation
Before preparing the phentolamine, immediate action must be taken to stop the ongoing tissue injury. These non-pharmacological interventions are crucial for all vasopressor extravasations.
- Stop the infusion immediately: As soon as extravasation is suspected, the infusion of the offending vasopressor must be stopped.
- Do not remove the catheter yet: Keeping the catheter in place allows for the aspiration of any remaining drug from the site before removal. Attempt to withdraw any blood or extravasated fluid through the catheter.
- Elevate the affected limb: Raising the extremity above the level of the heart helps to reduce edema and improve venous return.
- Assess and mark the area: Using a pen, trace the border of the affected area (e.g., area of blanching, pain, or swelling) to monitor its progression or resolution.
- Switch to a new IV site: If the patient still requires vasopressor support, a new intravenous access site, ideally a central line, must be established.
Preparing and Diluting Phentolamine
The correct preparation of phentolamine is essential for its effective administration. It is supplied as a lyophilized powder and must be reconstituted and diluted prior to injection.
- Retrieve phentolamine: Locate the vial of phentolamine mesylate.
- Reconstitute the powder: Inject a compatible diluent (e.g., sterile water for injection) into the vial to reconstitute the powder.
- Dilute the solution: The reconstituted solution should then be further diluted with 0.9% sodium chloride (normal saline) to achieve the required concentration for subcutaneous infiltration.
- Prepare multiple syringes: Instead of using one large syringe, it is best practice to divide the diluted solution into several smaller syringes (e.g., 1 mL syringes with fine needles like 25-gauge or smaller). This prevents needing to re-enter the skin with the same needle multiple times, reducing patient discomfort and the risk of infection.
Injection Technique for Extravasation
The method of injection is just as important as the preparation to ensure the antidote reaches the affected tissue. The goal is to liberally infiltrate the antidote throughout the blanched and hardened area caused by the extravasated drug.
- Utilize aseptic technique: Cleanse the skin around the extravasation site with an antiseptic solution.
- Administer in small aliquots: Using the pre-drawn, small syringes, inject the diluted phentolamine solution in multiple small aliquots.
- Target the edges: The injections should focus on the edges of the blanched or discolored area. The needle is inserted intradermally or subcutaneously.
- Inject through the catheter (optional): Some protocols suggest injecting an initial aliquot directly through the retained IV catheter before removing it to ensure some antidote reaches the central area of infiltration.
- Monitor for reversal: The effect of phentolamine should be almost immediate. The blanched area should turn noticeably pink or erythematous as blood flow returns. If the blanching does not reverse, or returns, additional doses may be required according to clinical protocols.
- Repeat if necessary: If symptoms of vasoconstriction (pain, blanching) persist, repeat the dose of phentolamine as clinically indicated and per institutional guidelines.
Post-Procedure Care and Monitoring
After injecting the phentolamine, continuous monitoring is critical to ensure a positive outcome and manage potential complications.
- Remove the catheter: After aspirating and injecting the initial aliquot, or if the catheter is no longer needed, remove it gently and apply light pressure to the site.
- Apply warm compresses: While data is limited, applying warm compresses for 15 minutes, four times a day, is generally recommended as a supportive measure.
- Observe and document: Monitor the extravasation site closely for changes in color, temperature, and swelling. Documentation of the procedure, dosage, and outcome is crucial.
- Monitor blood pressure: Since phentolamine can cause systemic vasodilation, closely monitor the patient's blood pressure, especially if they are hypotensive. Hypotension is a potential side effect.
- Consult specialists: For severe cases or if the tissue injury appears to be progressing, consult a plastic surgery team.
Comparison of Extravasation Treatments
| Feature | Phentolamine Injection | Warm Compresses & Elevation | Hyaluronidase |
|---|---|---|---|
| Primary Mechanism | Alpha-adrenergic blockade, reversing vasoconstriction. | Promotes vasodilation and improves drug diffusion and reabsorption. | Breaks down hyaluronic acid in connective tissue, increasing drug absorption. |
| Best for Extravasation of | Vasoconstrictive agents (e.g., norepinephrine, dopamine, phenylephrine). | Generally supportive care for most extravasations. | Non-vasopressor drugs, such as calcium gluconate. |
| Speed of Action | Rapid, often visible within minutes. | Gradual improvement over hours to days. | Moderate, depends on drug and infiltration. |
| Injection Technique | Multiple small subcutaneous injections around extravasation site. | Non-invasive external application. | Multiple intradermal/subcutaneous injections around affected area. |
| Key Advantage | Directly reverses the underlying cause of tissue ischemia for vasopressors. | Simple, low-risk, and supportive. | Can help disperse a wide range of drugs, particularly those with a high molecular weight. |
| Limitation | Only effective for vasoconstrictive agents. Requires careful administration and monitoring for hypotension. | Not sufficient for severe, high-risk extravasations. | Not the antidote of choice for vasopressors and requires different preparation. |
| Risk of Complications | Hypotension is a key risk, requires monitoring. | Very low risk. | Low risk of systemic complications, local risks similar to any injection. |
Conclusion
Knowing how to inject phentolamine for extravasation is a crucial skill for healthcare providers managing patients on vasopressor support. Prompt recognition of extravasation and the correct execution of the procedure—including immediate cessation of the infusion, aspiration, proper medication preparation and dilution according to established protocols, and targeted multi-site subcutaneous injection—can be the difference between a minor localized reaction and severe, irreversible tissue damage. As with any emergency procedure, it is vital to follow established hospital protocols, ensure accurate dosage, and continue to monitor the patient for both local resolution and systemic effects like hypotension. For further reading on extravasation management and pharmacology, resources from organizations like the National Institutes of Health can be valuable.
