Introduction:
In several medical and surgical subspecialties, including anesthesia, ophthalmology, otorhinolaryngology, dentistry, urology, and aesthetic surgery, topical anesthetics are utilized extensively. When applied directly, they result in a transient decrease in pain perception. It is possible to improve their distribution and efficacy by employing lipid delivery vesicles, free bases, physical and chemical permeation enhancers, drug concentration increases, and melting point decreases.
What Is Topical Anesthesia?
Local anesthetic injections can cause pain. It may exacerbate needle phobia and result in tissue edema, which may reshape the surgery site. All of these issues can be avoided by using topical anesthesia, which is becoming common in clinical settings.
Topical anesthesia is the direct administration of local anesthetic solutions, ointments, gels, or sprays that result in a superficial loss of sensation in the skin, mucous membranes, or conjunctiva.
How Are Topical Anesthetics Used in Plastic Surgery?
Local anesthetics are applied topically to block voltage-gated sodium channels, increasing the threshold for an action potential to occur and momentarily deafening the affected area. Due to the drugs' preference for affecting type C nerve fibers, which are responsible for pain, over type A nerve fibers, which are responsible for proprioception and pressure, patients may experience pressure during the treatment without experiencing pain.
What Are the Most Commonly Used Local Anesthetics?
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Lidocaine patches.
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A eutectic mixture of local anesthetics comprising lidocaine and prilocaine.
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A combination of lidocaine, epinephrine, and tetracaine is the most often used topical anesthetic.
What Are the Dosing Recommendations?
Lidocaine:
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Onset: 10–20 min.
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Duration of Action: 3–8 hours.
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Maximum Dosage in the Absence of Epinephrine: 4.5 mg/kg.
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Maximum Dosage in the Presence of Epinephrine: 7 mg/kg.
Mepivacaine:
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Onset: 10–20 min.
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Duration of Action: 3–10 hours.
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Maximum Dosage in the Absence of Epinephrine: 5 mg/kg.
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Maximum Dosage in the Presence of Epinephrine: 7 mg/kg.
Ropivacaine:
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Onset: 15–30 min.
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Duration of Action: 5–24 hours.
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Maximum Dosage in the Absence of Epinephrine: 3 mg/kg.
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Maximum Dosage in the Presence of Epinephrine: 3.5 mg/kg.
Bupivacaine:
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Onset: 15–30 min.
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Duration of action: 5–30 hours.
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Maximum Dosage in the Absence of Epinephrine: 2.5 mg/kg.
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Maximum Dosage in the Presence of Epinephrine: 3 mg/kg.
What Are the Uses of Topical Anesthetics in Aesthetic Dermatology?
Procedures in aesthetic dermatology are frequently accompanied by pain, which makes patients feel less comfortable and insecure. To lessen this uncomfortable feeling, local anesthetics are often utilized; these medications and treatments can be categorized as invasive or non-invasive. Topical anesthetic medications and cryoanesthesia are included in the first group. Because the second group is linked to the use of needles, administering the anesthetic agent can be uncomfortable on its own and cause anxiety in patients.
Dermatological procedures frequently involve the use of topical anesthetics. Nowadays, amide topical anesthetics like lidocaine and prilocaine are preferred over ester anesthetics like tetracaine, which frequently causes contact dermatitis. Eutectic Mixture of Local Anaesthetics, or EMLA, is the topical lidocaine that is most frequently used. This is an oil-in-water emulsion that contains 2.5 % prilocaine and 2.5 % lidocaine, along with an emulsifier made of polyoxyethylene fatty acid to improve absorption. EMLA reaches a depth of 3 mm after 60 minutes and a maximum dermal depth of 5 mm after 120 minutes. Longer application times and occlusion can be used to improve EMLA's penetration and effectiveness.
What Are the Uses of Topical Anesthetics in Laser Procedures?
Topical anesthetics and skin cooling are utilized in laser hair removal procedures. Research has demonstrated that EMLA cream works better than cooling the skin. Vascular lesions are frequently treated using lasers. Since cold and EMLA cream are vasoconstrictors, they should be used with extreme caution as they may seriously impede the process. The most common treatments for benign lesions are lidocaine-based infiltrative local anesthesia following laser removal or lidocaine/epinephrine and EMLA cream.
What Are the Uses of Topical Anesthetics in Fillers?
Because dermal filler injections are non-invasive and have a short recovery period, they are among the most popular cosmetic treatments used to repair unsightly wrinkles. The most common application for hyaluronic acid dermal fillers is soft tissue augmentation. Fillers are injected into different anatomical locations, and based on the area being treated, patients typically experience mild to severe pain.
Topical anesthetics or skin cooling may be applied before the injections. Nonetheless, it should be mentioned that EMLA cream functions as a vasoconstrictor in the context of lip augmentation and may momentarily cause the vermillion border to become blurry. Most fillers comprise lidocaine to lessen patient discomfort, and numerous studies have demonstrated their effectiveness in reducing pain and having a favorable safety profile without compromising their long-term viability.
What Are the Uses of Topical Anesthesia in Microfocused Ultrasound?
One of the most widely utilized non-invasive skin rejuvenation treatments these days for the full body is microfocused ultrasound. The devices cause heat coagulation in the subcutaneous and dermal tissues, which in turn causes denaturation of collagen and, ultimately, neocollagenesis. While the majority of patients tolerate the therapy well, it can occasionally be difficult to control pain throughout the process. The discomfort may cause the treatment areas to be reduced, the operation to take longer, the patient to use less energy, and the procedure's effectiveness to be limited. For pain relief, topical analgesics, cooling devices, and a single oral dose of ibuprofen are recommended; nevertheless, in many situations, these measures are insufficient.
Conclusion:
There are efficient local anesthetic techniques to control the pain associated with aesthetic dermatological procedures. Always choose them with care so as not to compromise the effectiveness of the chosen process. Considerations should also be made for the patient's preferences and the practitioner's experience. Given that topical anesthetic side effects can be severe and even fatal, practitioners must possess adequate understanding regarding them. Among the most significant problems in plastic surgery is severe postoperative pain. Additionally, more and more procedures are being done as day cases, which has led to an increased finding of the usefulness of local anesthetics.
