Practical Plastic Surgery

Toxicity

The risk for adverse reactions with local anesthetics is low, but it is important to be familiar with the signs and symptoms of toxicity. Some sites on the body are at greater risk for toxicity due to their robust blood supply. The face and scalp are rich in vascularity, and the systemic absorption of the drug from these sites is higher. In addition, patients with pseudocholinesterase deficiency, myasthenia gravis and those taking cholinesterase inhibitors are at a higher risk for overdose. Certain local anesthetics pose a higher risk of toxicity due to their lipid solubility. For example, bupivicaine is more lipid soluble than lidocaine and has a higher risk of toxicity.

7 The cardiovascular and CNS are the two systems most commonly affected by local anesthetic toxicity. CNS manifestations occur before cardiac signs, and the early signs and symptoms include restlessness, headache, disorientation, dizziness, blurred vision, tinnitus, slurred speech, nystagmus and twitching. Late signs of toxicity include generalized seizures, apnea and death. Treatment of seizures is by administration of a benzodiazepine such as diazepam or midazolam. Cardiovascular manifestations appear after those in the CNS and include myocardial depression, hypotension or shock, and dysrhythmias such as prolonged P-R interval and widening of the QRS complex. Of the commonly used local anesthetics, bupivicaine is the most cardiotoxic due to its strong affinity for the cardiac calcium channels.

Allergic Reactions

Allergies to local anesthetics are extremely rare, and account for less than one percent of adverse drug reactions during anesthesia. Reactions can range from a subtle rash to a full-blown anaphylactic response. The amides, such as lidocaine, rarely cause allergic reactions. The esters, however, such as cocaine, are metabolized by plasma pseudocholinesterase into PABA, and allergic reactions to these anesthetics are more common. If an allergic reaction does occur following administration of a local anesthetic, the culprit is usually one of the preservatives or additives in the solution rather than the anesthetic agent itself.

Pearls and Pitfalls

It has become increasingly clear that the maximum safe dose of lidocaine is much higher than previously thought. The traditional value of 7 mg/kg as the maximal dose of lidocaine with epinephrine is probably much too low. Recent literature supports a value closer to 35 mg/kg. Furthermore, the common use of dilute solutions of lidocaine with epinephrine has demonstrated that concentrations above 1% are not required. In the vast majority of cases, dilute solutions of lidocaine will provide adequate anesthesia, and the addition of epinephrine will greatly increase the maximal dose that can be safely used, while decreasing blood loss. One should wait at least 7-10 minutes for the vasoconstrictive effects of the epinephrine to take effect.

Suggested Reading

1.Ahlstrom KK, Frodel JL. Local anesthetics for facial plastic procedures. Otolaryng Clin N Am 2002; 35(1):29.

2.Baker IIIrd JD, Blackmon Jr BB. Local anesthesia. Clin Plast Surg 1985; 12(1):25.

3.Klein JA. Tumescent technique for regional anesthesia permits lidocaine doses of 35 mg/kg for liposuction. J Dermatol Surg Oncol 1990; 16(3):248.

4.Zilinsky I, Bar-Meir E, Zaslansky R et al. Ten commandments for minimal pain during administration of local anesthetics. J Drugs Dermatol 2005; 4(2):212.

a line that encircles the head (like a skull-cap). This line passes just above the tragus and through the glabella and occiput. A wheal should be raised in the subdermal plane along this line. About 10 ml of lidocaine is required every few centimeters.

Supraorbital Nerve Block

Indication

Anesthesia of the upper eyelid and medial forehead.

Technique

Palpate the supraorbital notch/foramen at the junction of the medial and middle

8thirds of the orbital ridge (about 2.5 cm off the midline of the face). Raise a wheal using a 25 gauge 1 inch needle. Advance the needle until the tip meets the foramen, and inject 1-2 ml while withdrawing.

Infraorbital Nerve Block

Indication

Anesthesia of the lower eyelid, medial cheek region or upper lip.

Extraoral Technique

Place the index finger in the canine fossa pointing caudal towards the infraorbital foramen. Raise a wheal using a 25 gauge 1 inch needle about 1 cm lateral to the ala of the nose. Advance the needle towards the tip of the finger until the tip meets the foramen on the maxilla. Inject 1-2 ml into the foramen and while withdrawing. The infraorbital canal runs in a superolateral direction.

Intraoral Technique

Retract the cheek with the thumb and introduce the needle into the upper gingival sulcus above the second bicuspid. Rest the syringe on the lower lip of the patient. Aim slightly laterally away from the midline along the maxilla until the infraorbital foramen is encountered. Inject 1-2 ml into the foramen and inject while withdrawing. The infraorbital canal runs in a superolateral direction.

Mental Nerve Block

Indications

Anesthesia of the lower lip, anterior portion of the lower jaw (including the anterior lower teeth).

Extraoral Technique

The mental foramen is located directly below the root of the second lower bicuspid at the midpoint between the lower and upper margins of the mandible. The needle is inserted into the skin and a wheal is raised. It is aimed inferolaterally towards the mental foramen, and anesthetic is injected while the needle advances until bone is met. After instilling 1 ml of anesthetic, the needle is used to palpate the mental foramen after which an additional 1 ml is injected into the foramen.

Intraoral Technique

With the mouth closed, the cheek is retracted and needle inserted into the gingivobuccal sulcus below the bicuspids. A wheal is raised, and the needle is aimed

towards the root of the second bicuspid and advanced at 45˚ until bone is reached. After instilling 1 ml of anesthetic, the needle is used to palpate the mental foramen after which an additional 1 ml is injected into the foramen.

Regional Block of the External Nose

Indications

Anesthesia of the skin of the nose.

Technique

The two sides of the nose should be anesthetized separately. The needle is introduced into the skin about 1 cm lateral to the alar base. A wheal is raised, and the 8 needle is advanced towards the radix; 2-3 ml is injected along this line. The needle is withdrawn almost completely and then directed downward towards the oral commissure. An additional 1-2 ml is injected along this course. The entire procedure is repeated for the other side of the nose.

Regional Block of the External Ear

Indication

Anesthesia of the ear.

Technique

The anterior ear is supplied by the auriculotemporal nerve and the posterior ear by the greater auricular nerve and occipital nerve (including its mastoid branch). These nerves all reach the ear from the superior, posterior and inferior directions only. A needle is inserted 2 cm above the helix and advanced anteroinferiorily and posteroinferiorily. The needle is removed and inserted 3 cm posterior to the ear and advanced anterosuperiorily and anteroinferiorily. The needle is removed and inserted 1 cm below the ear, advancing it posterosuperiorily and anterosuperiorly. When these three injections are completed, a continuous infiltration around the entire ear (excluding the anterior portion) has been achieved.

Radial Nerve Block

Indication

Anesthesia of the radial dorsum of the hand and proximal thumb, index and middle finger. The ring finger should also be blocked with an ulnar nerve block.

Technique

1.Identify extensor pollicus longus (dorsal tendon of the anatomical snuffbox).

2.Insert the needle over the tendon at the base of the first metacarpal.

3.Inject superficial to the tendon (about 2 ml) and over the snuffbox (1 ml).

Median Nerve Block

Indication

Anesthesia of the palmar side of the thumb index finger and middle finger, and radial side of the ring finger. Also, the nailbeds of the above fingers can be blocked with this technique. The thenar region (palmar cutaneous branch of the median nerve) can also be blocked.

Technique

1.Identify flexor carpi radialis and palmaris longus by having the patient make a clenched fist and slight wrist flexion.

2.Insert the needle 2 cm proximal to the proximal wrist crease.

3.As the needle passes through the flexor retinaculum, 3 ml of anesthetic is injected.

4.Injection of an additional 1 ml above the retinaculum will anesthetize the palmar cutaneous branch supplying the thenar eminence.

Technique

1.Identify flexor carpi ulnaris by having the patient forcefully ulnar deviate the wrist slightly with the fingers fully extended.

2.The ulnar nerve lies radial to the flexor carpi ulnaris tendon.

3.Insert the needle 2 cm proximal to the wrist on the radial side of the tendon directed towards the midline.

4.After parasthesias are felt, inject 4 ml of anesthetic in a fanwise fashion along the course of the nerve.

Digital Nerve (Ring) Block

Indications

Anesthesia of the digit.

Technique

1.With the dorsum of the hand facing upward, insert the needle into the dorsal skin at the midpoint between the digits (the apex of the “V” of the web space) and raise a wheal.

2.Advance the needle towards the palm perpendicular to the skin and infiltrate along this course about 2 ml of anesthetic.

3.Withdraw the needle almost completely and then begin advancing the needle towards the middle of the digit, infiltrating the skin on the dorsum of the finger base.

4.The digital nerves on either side of the finger should be anesthetized in this manner.

Pearls and Pitfalls

1.The supraorbital, infraorbital and mental foramena all lay along a vertical line that also includes the pupil in the midgaze position. Therefore, if any two of the foramena have been located, the third can be easily found.

2.Epinephrine requires about 10 minutes until full effect, and the same is true for lidocaine used in a regional block. Therefore, one should administer the block in advance.

3.Several studies reviewing thousands of cases of digital anesthesia have found that using epinephrine in the digits is entirely safe, with almost no cases of digital ischemia secondary to the epinephrine. However, until a prospective trial demonstrates the absolute safety of this practice, epinephrine should not be used in the digits.

4.An adequate block is not always 100% successful at eliminating pain from the site of injury. Often a supplemental field block is required after the initial regional block has taken effect.

Suggested Reading

1.Stromberg BV. Anesthesia. In: McCarthy JG, ed. Plastic Surgery. 1st ed. Philadelphia: WB Saunders Company, 1990.

2.Wedel DJ. Anesthesia in hand and upper extremity surgery. In: Berger RA, Weiss AC, eds. Hand Surgery. Philadelphia: Lippincott Williams and Wilkins, 2004.

3.Zide BM, Swift R. How to block and tackle the face. Plast Reconstr Surg 1998; 101(3):840-51.

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as well as on the vital signs and level of arousal of the patient. The fact that the patient is conscious and can shift position or move freely, necessitates that the surgeon be prepared to stop working at any moment. Nevertheless, many patients are well-suited for conscious sedation.

Preoperative Considerations

Prior to using conscious sedation for the first time, the surgeon must familiarize herself with the medications she will be using, as well as their side effects and reversal agents. She must also be familiar with ACLS protocol, airway management and have readily available resuscitation equipment. Immediate access to an anesthesiologist in case of emergency is strongly recommended.

Proper patient selection is an important preoperative decision. Those with moder-

ate to significant cardiopulmonary disease are poor candidates. Patients should meet 9 the criteria of the American Society of Anesthesiologists status I or II. This means that candidates for conscious sedation should be healthy or have only a mild systemic disease that results in no functional limitation (e.g., obesity, diabetes, hypertension and extremes of age). All other patients should receive monitored anesthesia care by an anesthesiologist or general anesthesia. Furthermore, individuals with anxiety disorders and extreme fear of the operating room may not be suited for conscious sedation.

Prior to the procedure, patients may benefit from premedication with intravenous diazepam (Valium), administered in increments of 5-10 mg. The dose administered usually ranges from 10 to 50 mg, with the goal being adequate preoperative subjective relaxation of the patient with the desired endpoint being of slurred speech. Oral diazepam is also an option; however, it has to be given almost an hour prior to the procedure in order to be effective. A second medication that should be administered preoperatively is an antiemetic. Ondansetron (Zofran), given as a single 4 mg intravenous injection is used routinely at our institution. Recently, we have found that clonidine (0.1-0.3 mg PO) given 30 minutes prior to the procedure is not only effective in lowering blood pressure during surgery, it also contributes significantly to patient relaxation during the procedure. It does, however, cause post-procedure orthostatic hypotension.

Intraoperative Considerations

Tumescent Anesthesia

As stated previously, conscious sedation—as it pertains to plastic surgery, involves the administration of local anesthesia in addition to the intravenous sedation. In fact, it is the methodical use of tumescent anesthesia that ensures a smooth, relatively pain free procedure. Tumescence, or wetting solution as it is more appropriately termed, should be infiltrated into the surgical field. Two goals should be kept in mind: anesthesia of the sensory nerves and vasoconstriction of the blood vessels in the region. Achieving these goals requires at least 10 minutes for the wetting solution to exert its effects. Two solutions are commonly used at our institution:

Liposuction solution

Face/breast solution

40 Practical Plastic Surgery

Note: all medications listed are given intravenously.

Intravenous Sedation Regimens

Although there are a number of intravenous sedation regimens available, an excellent choice is the combined use of midazolam (Versed) and fentanyl (see Table 9.1). The advantage of using this combination is that midazolam has both anxiolytic and amnestic effects, whereas fentanyl is a potent, short-acting analgesic. The combination of fentanyl and midazolam is superior to midazolam alone in decreasing patients’ subjective report of pain and anxiety. The main drawback of fentanyl is respiratory depression; however unlike other commonly used intravenous opiates such as morphine, it does have a very short half life. Midazolam, in contrast, has minimal effects on the respiratory system except in the elderly, in which lower doses should be utilized. Both of these medications have antagonists. Flumazenil (Mazicon) and naloxone (Narcan), the antagonists of midazolam and fentanyl respectively, should be readily available in the operating room.

Another method of intravenous sedation involves the use of propofol in combination with an opiate and benzodiazepine. The fact that a deeper level of sedation can be maintained makes this technique preferable for selected patients who are very anxious. Nevertheless, the disadvantage of this combination is the higher risk of respiratory depression, and the lack of a reversal agent for propofol. This technique necessitates a higher degree of experience and training in anesthetic technique including the ability to intubate the patient if needed. The use of propofol is not discussed in this chapter.

In the operating room, one nurse should be responsible for continuously monitoring patient status using pulse oximetry, blood pressure and cardiac monitoring. This should be performed by a nurse with appropriate experience and background in continuous patient monitoring; however specialized anesthesia training is usually not needed. It is important to emphasize that this nurse should have no other duties to perform during the procedure. The patient’s oxygen saturation, blood pressure, heart rate, level of arousal and respiratory status should be monitored

every 5 minutes. Changes in vital signs, level of arousal and the oxygen saturation are communicated to the surgeon. In addition, the surgeon should make his own assessment of arousal based on response to verbal stimulation, as well as the patient’s degree of discomfort.

Based on the patient’s condition, 0.5 to 2 mg of midazolam should be administered at the 5 minute intervals. In addition, fentanyl should be given in increments of 12.5 to 50 mcg. After local anesthetic is infiltrated, fentanyl administration is infrequently required, except in preparation for subsequent local anesthetic administration to a new surgical site. The total dose of fentanyl should rarely exceeded 200 mcg over the course of the procedure. Toward the end of the case, the amount of sedation should be decreased to allow the patient to slowly return to a normal state of arousal and awareness.

During conscious sedation, supplemental oxygen is usually not necessary. The 9 ability of the patient to maintain an oxygen saturation over 95% without supplemental oxygen is a useful guideline to avoid oversedation (crossing from conscious

to deep sedation). Occasional periods of deep sedation may occur, usually lasting for a few minutes at most. Brief stimulation and rarely jaw thrust may be required to maintain adequate ventilation. The use of small incremental doses of midazolam, limited use of narcotics and effective local anesthesia help to limit episodes of deep sedation. Nevertheless, as a safety measure, the capability to convert to general anesthesia or immediate assistance from an anesthesiologist should always be available. Foley catheters and sequential compression devices are generally not required due to the relatively short length of procedures utilizing conscious sedation, and the fact that venous stasis is minimal due to spontaneous patient movement and leg muscle contractions. For cases involving large volume liposuction or those that are longer than a few hours, a Foley catheter should be used to monitor fluid status and to allow greater flexibility in intraoperative fluid resuscitation.

Postoperative Considerations

Following the procedure, many hospitals will allow patients to bypass the recovery room and proceed directly to the outpatient day surgery area. This saves the patient the extra costs of recovery room care. Patients are monitored postoperatively in a standard manner. Those who choose to go home the day of surgery must meet criteria for discharge (ability to ambulate to a chair and the bathroom, bladder control, tolerate oral intake without emesis). Patients who received preoperative clonidine must be monitored for orthostatic hypotension.

Inpatient stay in an observation unit is appropriate for longer cases that involve multiple procedures, as well as for older patients who live alone. Postoperative nausea and vomiting is the major factor contributing to unintentional hospital admission after outpatient surgery. It begins shortly after arrival in the recovery room and usually lasts no longer than 12-24 hours postoperatively. A number of studies support the administration of a preoperative antiemetic (see preoperative considerations).

Pearls and Pitfalls

One of the risks of conscious sedation is crossing over into deep sedation. The responsible surgeon and monitoring nurse should be able to identify and handle patients who briefly slip into deep sedation. In very rare instances, a patient may require jaw thrust, mask ventilation or narcotic reversal. It is critical that the surgeon be comfortable performing these steps if necessary. A common pitfall leading to