Lido: The Many Uses of Local Anesthesia in Aesthetics
Mar 25, 2022
Since it was discovered in the late 1940s, lidocaine (lido) has become one of the most commonly used local anesthetics in medicine. The primary mode of action of this local anesthetic agent is a blocking of sodium ion channels in the nerve cell membranes, such that the neurons in the infiltrated subcutaneous tissue become transiently incapable of sending pain signals to the brain. Lidocaine is a local anesthetic that also decreases muscle contraction and has effects such as vasodilation and hypotension. Consequently, lidocaine is considered a Class IB anti-arrhythmic agent. Lidocaine is on the WHO's list of essential medications. Millions of prescriptions are written worldwide for lidocaine, which is available as a low-cost generic.
In modern-day medicine, lidocaine and other local anesthetic agents are used to numb sensations and facilitate local anesthesia for a wide variety of surgical procedures. They are widely used in dentistry with a very low rate of adverse events. Lidocaine is particularly useful in aesthetic surgery, given that the procedures are elective and patient comfort is paramount. Moreover, local anesthesia when used along with sedation offers plastic surgeons even greater flexibility in personalizing the degree of anesthesia to the patient's needs.
Plastic surgery procedures that previously required intravenous regional anesthesia or general anesthesia can now be safely performed in the office or outpatient surgical suite under local anesthesia due to advancements in techniques and agents. Patients can now undergo relatively lengthy and complex plastic surgery procedures on an outpatient basis and be discharged home more quickly and safely. A patient who is alert, has minimal pain, and no nausea or vomiting upon discharge after aesthetic surgery will undoubtedly rate their surgical experience as a positive one. The choice and route of anesthesia administration is therefore of great importance to the patient's overall surgical experience after plastic surgery.
Local anesthesia includes local infiltration of the surgical site, peripheral nerve blocks, and tumescent techniques. The local anesthetic agents commonly used are amino amides. They include lidocaine and other local anesthetics such as bupivacaine, mepivacaine, prilocaine, and etidocaine. Each of these agents as a different potency, onset of action, and duration of action.
Dozens of plastic surgery and dermatologic surgery procedures are routinely performed using local anesthesia, common examples being liposuction, facelift, lip lift, upper eyelid blepharoplasty, buccal fat excision, fat grafting, breast augmentation with implants, and otoplasty.
Adverse effects of lidocaine usually occur when the plasma lidocaine concentration reaches toxic levels. Smaller amounts can result in lidocaine toxicity if it is given intravascularly. Given that lidocaine has a narrow therapeutic index, it may be necessary to monitor plasma levels in patients with hepatic impairment. Local anesthetic toxicity can also result in methemoglobinemia if very high doses are given or at lower doses in patients with hemoglobinopathy or anemia due to another cause.
Monitored Anesthesia Care
Procedures such as liposuction, fat grafting, implants, facelift, blepharoplasty, and otoplasty are routinely performed under monitored anesthesia care (MAC), which is a combination of intravenous administration of sedation and local anesthetic injection, nerve blocks, or infiltration including tumescent anesthesia. MAC is associated with a lower incidence of nausea and vomiting compared to general anaesthesia. Also, the patient can typically be discharged home more quickly and safely.
The main disadvantages of MAC, of course, is a lack of airway control and the risk of obstruction or aspiration. These risks can be minimized by carefully titrating the medications to maintain spontaneous respirations while ensuring a depth of anesthesia sufficient enough to keep the patient comfortable.
General anesthesia (GA) is the preferred method of anesthesia for complex or lengthy procedures since it is associated with analgesia, amnesia, and muscle relaxation. Additionally, an endotracheal tube or laryngeal mask secures the patient's airway, thus minimizing the risks of obstruction or aspiration. Aesthetic surgery procedures such as rhytidoplasty, open rhinoplasty, and buttock implants are done using conscious sedation or GA. Thoracic epidural anesthesia can be used for plastic surgeries involving the breast, abdomen, buttocks, and liposuction, with continuous hemodynamic and respiratory monitoring for safety.
The main disadvantage of general anaesthesia is postoperative somnolence and an increased incidence of nausea and vomiting. An alternative that bridges the gap between MAC and GA is total intravenous anesthesia (TIVA), in which full intravenous sedation is used along with airway management with a laryngeal mask.
There are, of course, regulatory aspects and safety protocols, but at the present time, many procedures that were previously required to be performed in a hospital operating room can now be performed in an ambulatory surgical care center or non-operating room setting.
As with all surgeries, appropriate patient selection for any type of plastic surgery under anesthesia should start with a meticulous medical and surgical history and exam. In aesthetic surgery, an additional factor that contributes to the choice of anesthetic is the patient's attitude. While some patients prefer to be asleep for the surgery due to trepidation about pain, others have a fear of general anaesthesia or "having a tube stuck in my throat." If a patient is particularly anxious or uncooperative, deep sedation may be necessary during the procedure, deeper than originally planned, thus potentially compromising patient safety.
Pain Medicine Tips
Local anesthetics are commonly used in dermatology and plastic surgery. Here are some techniques for minimizing the pain associated with local anesthetic injection. The implementation of these techniques can give patients a nearly pain-free experience and improve satisfaction for both patient and surgeon.
Use Smaller-Gauge Needles
This is an obvious technique to reduce injection pain. Typically, 27- or 30-gauge needles are recommended as least painful.
Limit Repeated Use of the Same Needle
Dull needles result in more painful injections of local anesthetics. Try to use a fresh needle for multiple injection sites or multiple injections into the same area.
Use Buffered Lidocaine
The commonly used lidocaine 1% with 1:100,000 epinephrine is more acidic than plain lidocaine. Buffering lidocaine and epinephrine with sodium bicarbonate in a 10:1 dilution raises the pH of the solution from 4.2 to 7.4, which is more comfortable for patients. Notably, bupivacaine is more acidic than lidocaine.
Warm the Anesthetic
You can reduce injection pain by warming anesthetics to body temperature (temperatures of 40°C to 54.4°C (104°F–130°F) are safe and recommended). Combining buffering and warming can reduce local anesthetic injection pain considerably.
Slow injection of small volumes can significantly reduce pain because it gives the nerve endings in the skin a chance to accommodate to the distortion caused by the infiltration of the local anesthetic.
Use a Perpendicular Injection Technique
Lidocaine injected at a 90° injection angle is associated with significantly less pain compared to a 45° angle because fewer nerve endings contact the needle.
Perform Pulse Injections
Compared to continuous injection techniques, pulse injections may be less painful. This involves injecting a small amount (0.1 cc) of anesthetic, waiting for 3 seconds, and repeating this process a few times with larger volumes injected on subsequent pulses.
Inject Blanched Areas During Multiple Needle Reinsertions
When a large areas is to be anesthetized with subcutaneous administration of a local anesthetic, one way to ensure that lidocaine has already infiltrated an area and will thus provide anesthesia is by performing the needle reinsertion within 1 cm of a blanched area.
Distract the Patient
Distraction through conversation or music, pinching, scratching, stretching, or having the patient look at something else can help to reduce the discomfort associated with injecting local anesthetics.
Combine with Topical Anesthetics
Application of a topical anesthetic 1-2 hours before intralesional anesthetic injection can help to reduce injection pain. Ethyl chloride spray, which has a faster onset of action than topical anesthetics, may also be employed.
More and more aesthetic surgery procedures can now be done safely with local anesthesia. Plastic surgery procedures done using local anesthetic injections can greatly enhance a patient's surgical experience. Incorporating the techniques that help to minimize the pain associated local anesthesia injections can further reduce discomfort and enhance patient satisfaction.
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