9 Local anesthetics in plastic surgery

Synopsis

Local anesthesia is widely used for minor surgery.

Local anesthesia use can be extended to incorporate larger surgeries.

The benefit to the patient is to avoid general anesthesia while breathing spontaneously.

Using bupivacaine in the anesthetic solution, four to six hour surgeries are also possible and bupivacaine provides some hours of postoperative pain relief.

In each region, an intelligent infiltration anesthesia technique is preferable to tumescent technique.

For large procedures, the assistance of the anesthesiologist provides better sedation as well as the benefit of shared responsibility.

Introduction

For aesthetic surgery and short or superficial operations, such as rhino-otoplasties or facelifts, some surgeons have been using local anesthesia with great success. Lately, larger aesthetic surgeries have been performed with the use of local anesthesia under superficial or deep sedation.

While general anesthesia released the surgeon from the responsibility of caring for a sleeping patient, some others prefer to use sedation and local anesthesia because of their advantages: the use of gases, muscle relaxants, and tracheal intubation are avoided, sedation can be regulated, there is less bleeding during surgery, and postoperative analgesia may be easier to manage. Furthermore a smooth and easy recovery with early discharge helps to diminish costs and improve efficiency as well as safety.

When the surgeon decides to use local anesthesia and sedation, four steps should be considered: (1) selection of the patient; (2) selection of sedation-analgesia; (3) selection of anesthetic drugs; and (4) selection of infiltration techniques.

Historical perspective

In the 18th century, operations were performed using gases like chloroform or ether but the mortality rate was high. Therefore, surgeons were interested in finding other kinds of harmless anesthesia.

In 1860 in Göttingen, Albert Nieman reported the anesthetic properties of cocaine, a drug obtained from a Peruvian bush. When an ophthalmologist from Vienna named Carl Kohler had an inflammatory process in his gums, his friend Sigmund Freud, who was familiar with Nieman’s work, used cocaine leaves to relieve his pain. After this experience, in 1883 Kohler performed the first cataract surgery with great success using cocaine as a local anesthetic.

Old reports show that since 1880 Maximilian Oberst, in Halle, had been operating on patients by injecting cocaine under the skin while an assistant was compressing the veins to avoid the rapid absorption of the toxic effects of the cocaine. Some other German surgeons were using subcutaneous cocaine for minor surgeries; however, some cases of overdose as well as some fatal outcomes were also reported. In 1890, Carl Schleich,¹ a German surgeon from Berlin, demonstrated in the German Congress of Surgeons the anesthetic properties of different dilutions of cocaine to perform surgeries in order to avoid toxic doses. The era of using dilutional anesthetics had begun.

At that time, William Halstead,² an American surgeon, son of a German family, was in Berlin learning the use of cocaine as a local anesthetic. He took this practice back to America and began to use cocaine at the Johns Hopkins Hospital in Baltimore.

In 1905 a synthetic alkaloid named novocaine, similar to cocaine but with less toxic effects, was developed by A Einhorm in the Hoechst laboratories in Darmstadt. From then on, this new, less toxic anesthetic was used for local anesthesia and more extensive surgeries could therefore be performed. When Takamine and Aldrich in the Parke Davis laboratories in London developed suprarenine (later named adrenaline or epinephrine) and its vasoconstrictive effects, a surgeon from Heidelberg named Heinrich Braun ³ adopted this drug and began to use it in combination with novocaine to avoid bleeding as well as to slow the absorption of anesthetic. In 1905, Braun published his first book, which went on to be reprinted seven times; it was a complete compilation of all local-regional anesthesia for almost all sorts of surgery. Braun is recognized as “the father of local anesthesia.”

Carl Gross,⁴ a German surgeon, also reported that the action of local anesthetics would last longer if they were diluted in a saline solution. As we can see, a very old idea was rediscovered at the end of the last century. Läwen^5,⁶ in 1910 experimented on himself with novocaine diluted in a bicarbonate solution, reporting that in this way he obtained a more rapid and lasting anesthetic effect With regard to injection methods, Moskowicz⁷ in 1901 replaced injection syringes with an infusion bottle filled with anesthetic solution, following the same principle used by Matas,^8,⁹ and later perfected by Kirschner in 1931,¹⁰ when he developed a device using carbon anhydride gas. This device facilitated infiltration under pressure, and was known as Hochdruckanestesierunapparat. Different devices powered by an electric-driven motor or using the principle of the infusion bottle are largely used nowadays in plastic surgery.

The Russian surgeon Alexandr Vishnevsky ¹¹ reported the use of novocaine diluted in 1000–2000 mL saline solution for thoracic and cardiac surgery. In the Berlin Congress of Surgery in 1955, he reported having an experience of 1193 thoracic and cardiac surgeries with this anesthesia.

Today, many plastic surgeons perform different aesthetic and reconstructive procedures under local anesthesia. These include rhinoplasties, facelifts, breast surgery, liposuction, and some lipectomies. However it has to be remembered that the idea of performing surgery under local anesthesia, new anesthetics, vasoconstrictors, large anesthetic dilutions, alkaline anesthetic solutions, devices for infiltrations, and almost everything that is used today in plastic surgery throughout the world was developed or described at the end of the 18th century and at the beginning of the 19th century by German and Russian surgeons.¹²^–¹⁴

Patient selection

There are patients for general, epidural, and local anesthesia. If you fail to select the ideal anesthesia for the patient, problems can arise during surgery.

Preoperative evaluation of the patient should pay particular attention to issues such as age, general physical condition, personality, preference for local anesthesia, drug history, and the extent of surgery.

Once these issues are considered, the surgeon can make a decision on whether or not the patient is a suitable candidate. One factor that has to be considered is cost. In general, having a procedure done under local anesthesia is cheaper than the same procedure under general anesthesia. For this reason, the surgeon may be tempted to treat a patient under local anesthesia when general anesthesia would be a better choice for that patient. Such a “borderline” case is fraught with potential problems and making the decision purely on economic grounds should therefore be avoided.

The borderline patient can be termed thus because (s)he usually has abnormal fears, and possibly a labile personality. One other very important factor is the confidence of the surgeon in his/her ability to perform the particular operation under local anesthesia.

In my experience, fear is one of the most important obstacles to this kind of anesthesia because it is a reaction that appears when a person thinks that something is threatening him or her, and the person’s responses become exaggerated and somewhat unpredictable.

Age is important. In general, teenagers may sometimes be difficult since they lack maturity and experience and may sometimes, as a consequence, behave unpredictably. Patients who are ignorant of the procedure may also fear the unknown and may be less suitable candidates. Sometimes, despite extensive explanation, patients cannot grasp the essence of the procedure and may therefore be less than ideal candidates for local anesthesia. Sometimes these fears and exaggerated responses may be related to such diverse issues as ethnicity, life experiences, and personality.

Patients with abnormal or exaggerated fears should not be accepted for local anesthesia, but others who are afraid of only some aspects of the surgery can be deemed suitable and placed in the group of ideal candidates, following a very good explanation of how the surgery is performed. This explanation should include a description of the level of anesthesia, and perhaps a visit to the operating room before surgery with someone who can answer the patient’s questions and help to ease anxiety and nervousness.¹⁵

Choice of sedation

Sedation means depressed consciousness and, indirectly, decreased discomfort during surgery. In general, this allows the patient to tolerate a procedure by relieving anxiety, discomfort, and pain.

There are several ways to sedate a patient. There are also different levels of sedation. Some surgeons use only a mild sedative, choosing to perform operations with the patient awake. Others have the patient under moderate sedation but maintaining verbal contact, while others prefer to have the patient completely asleep, that is, in deep sedation. Deep sedation may be accompanied by a partial or complete loss of protective reflexes and may include the inability to maintain a patent airway. Planned deep sedation should be administered preferably by an anesthesiologist or certified registered nurse anesthetist under the direction of an anesthesiologist or an operating physician.¹⁶

Premedication

Sedation-analgesia begins with premedication. Very nervous patients should be medicated some days prior to surgery; otherwise it can be very difficult to calm them down once they are in the operating room.

Lorazepam has been demonstrated to be a very effective drug. It is usually administered the night before surgery and again when the patient wakes up on the morning of surgery. In this way anxiety as well as gastric secretions are reduced.¹⁷ Premedication should also vary according to each patient.

Sedation

The ideal situation is to receive a sedated patient in the operating room. Midazolam is the most common drug administrated in the operating room. It can be administered intramuscularly (IM) or intravenously (IV) 15–30 minutes before surgery. For more extensive procedures a combination of narcotics and anticholinergics, like scopolamine or atropine, can be used for each patient depending on degree of nervousness, blood pressure, and other physiologic indicators. For short procedures and for the beginning of longer ones, the most common combination is midazolam–fentanyl. Thirty minutes after this injection, the patient arrives at the operating room very calm, relaxed, or sleepy, so that he or she is not very aware of what occurs during the preoperative preparations. Sometimes this premedication is sufficient, but if the patient needs more profound medication, then the surgeon has several options.

Drugs used for sedation include diazepam, midazolam, or propofol, while for analgesia ketamine and fentanyl can be used. Some surgeons like Thomas Baker ¹⁸ or Charles Vinnik¹⁹^–²² use a combination of midazolam–ketamine. This is referred to as dissociative anesthesia. Ketamine is a short-acting drug that provides a rapid dissociative anesthesia lasting 45 minutes IM and 10–15 minutes IV. It has a short recovery time and is especially indicated for hypotensive patients. According to Ersek,^23,²⁴ it also decreases platelet aggregation.

The initial decision is whether the patient needs sedation, analgesia, or both.

For sedation, the effects of diazepam and midazolam are similar but their duration differs: 3–4 hours or sometimes less for midazolam and 6–12 hours for diazepam.

For analgesia, ketamine is a very safe neuroleptic drug that does not depress the central nervous system (CNS). On the contrary, it stimulates it (not recommended for nervous or hypertensive patients); while fentanyl is a narcotic that depresses the CNS (not recommended for hypothyroid or hypotensive patients).

Intraoperative administration of drugs should be IV and in small doses using short intervals of some minutes, in order to titrate the minimal doses and not to administer unnecessary overdoses.

The effect of ketamine and fentanyl lasts 10–20 minutes but all medication wears off faster when the patient is nervous or has tachycardia, because the metabolism of the drugs is accelerated.

In the operating room, if the surgeon is alone, a nurse or another person should monitor the patient’s vital signs, in spite of the convenient alarms of the pulse oximeter or cardioscope monitors.

If the local anesthesia has been correctly infiltrated and the patient wakes up during surgery, the anesthesiologist or the surgeon has to evaluate whether the patient needs further sedation, intravenous analgesia, or complementary local anesthesia.

Propofol is a hypnotic drug with a very short effect that needs repetitive administration or a continuous infusion that must be monitored by an anesthesiologist.

For sedation and analgesia, the surgeon has to study the effect of a few drugs he/she will use and combine, along with the optimal doses, metabolism, and side-effects. Under superficial sedation the patient may wake up and secrete epinephrine, which activates hepatic and renal metabolism, raises blood pressure, and increases the metabolism of anesthetic and sedative drugs. For this reason some surgeons prefer deep sedation.

If the surgeon wants to operate under deep sedation, it is preferable to have an anesthesiologist monitor the patient. This shared responsibility eases the stress of the procedure and makes for a safer environment for the patient.

Selection of local anesthetics

The effect of local anesthesia is achieved by four mechanisms: (1) chemical nerve blockade; (2) compression of the nerves; (3) distension of the nerves; and (4) ischemia of the nerves produced by vasoconstrictors. The effect of the anesthetic depends on the concentration of the drugs, the use of epinephrine, the blood supply of the area injected, and the thickness of the nerves.

There are several different anesthetic drugs, but each one should be considered according to the duration of its effect. The author’s experience in infiltrative anesthesia is with lidocaine and bupivacaine.

Anesthetic drugs

Lidocaine is a very old and safe anesthetic drug that allows 90 minutes of numbness. Its standard dose is 500 mg for a 70-kg person, or 7 g/kg, or 25 mL of lidocaine 2%, but it is known that these doses can be augmented many times (some papers mention up to five times the maximum recommended dose) (Fig. 9.1).

Fig. 9.1 Anesthetic solution with 25 mL lidocaine 2%, 25 mL bupivacaine 0.5%, epinephrine (adrenaline) 1/1000 1 mL and saline solution up to 500 mL.

Bupivacaine is a long-lasting anesthetic that is largely used in block anesthesia and, in plastic surgery, is mainly used for postoperative pain relief. Its dose is 1.25 mg/kg, 25 mL of 0.50% bupivacaine for a 70 kg person without ephinephrine. In the author’s experience, 3.3 mg/kg can be used safely when it is very diluted and with the addition of ephinephrine. This drug has an onset of 15–30 minutes and profound conduction blockage that lasts around 6–12 hours.

Vasoconstricting agents

Vasoconstriction can be achieved in different ways. The main and more popularized drug is epinephrine.

The standard concentration of epinephrine is 1 : 1000 and it can be diluted in 100/500/1000 mL, obtaining a dilution 1 : 100 000, 1 : 500 000 or 1 : 1 000 000. This drug’s vasoconstrictive action lasts 1–6 hours and causes central effects such as tachycardia and hypertension.

Ornipressin is a vasoconstrictive agent without central action (it does not raise the blood pressure nor alter the cardiac rhythm). Its vasoconstrictive effect lasts 4–6 hours. One milliliter can be diluted in 250, 500, or 1000 mL of saline solution and can be combined with any anesthetic. All vasoconstrictors have the capacity to produce ischemia in the peripheral nerves that blocks the conduction of stimulus. As long as the vasoconstriction lasts, so does the anesthesia. The trade name for omnipressin was Por-8 (Sandoz) but for the moment, it has been discontinued.²⁵

Carbonated anesthesia

Anesthetic pH is usually 6.4, which produces some pain at the time of infiltration. To avoid this, it has been advocated to add sodium bicarbonate to raise the pH to 7.4. The duration of local anesthesia when using bupivacaine and carbonated anesthesia is unknown.

There are many formulae that combine different anesthetics and vasoconstrictors.

For large aesthetic surgeries Mottura’s formula ²⁶^–³³ is to combine 20 mL lidocaine 2% (7 mg/kg), 20 mL bupivacaine (1.5 mg/kg), and 1 mL epinephrine 1 : 1000. These drugs can be diluted in 400–1000 mL saline solution or lactated Ringer’s (Fig. 9.1).