Anesthesia in aesthetic surgery

Published on 22/05/2015 by admin

Filed under Plastic Reconstructive Surgery

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1609 times

CHAPTER 3 Anesthesia in aesthetic surgery

Michael Zelman, Daniel J. Ceradini

History of ambulatory anesthesia

The origins of anesthesia began with a series of events in the mid 1800s. While training in New York City, Crawford Long experienced the recreational use of ether and nitrous oxide during student parties: the so-called “ether frolics”. After starting his practice, he applied the use of diethyl ether to anesthetize a patient during removal of two small tumors from a man’s neck in 1842. He did not publish his methods until 1849, several years after the use of nitrous oxide was reported by Horace Wells and the first successful public demonstration of nitrous oxide by William T.G. Morton in 1846. These pioneers set the stage for the rapid integration of anesthesia into surgical practice, which proceeded over the latter half of that century.

Shortly after World War I, with increasing popularity of office-based surgery, the utilization of a dedicated anesthesiologist in the office setting was first described by Ralph Waters in 1919. He described his experiences administering anesthesia in the surgeon’s office, where his responsibilities included supplying the operating room, recovery room, and his private doctor’s “loafing and smoking room”. He recognized the financial potential of his situation, and noted that success was intimately tied to the satisfaction of the surgeon.1

Later in the mid-20th century, with rising costs and inefficiency of inpatient care and increasing shortage of hospital beds, there was significant transition to outpatient surgery. In an effort to maximize patient throughput, cut costs, and maximize reimbursement, John Ford and Wallace Reed designed the first freestanding ambulatory surgicenter in Phoenix, Arizona in 1969. Most cases in this facility were performed under general anesthesia. Based on their drive for efficiency, this stimulated the development of anesthetic regimens and postoperative medications that would allow patients to return home sooner. These techniques continue to evolve today.

Over 60% of all surgical procedures performed in the US are in an ambulatory setting. In aesthetic surgery, the vast majority of procedures are performed in the outpatient or office setting. Functional knowledge about of the practice of anesthesia and how it can be applied to the aesthetic surgeon’s practice is vital to success.

Preoperative evaluation – patient safety

Ambulatory anesthesia has evolved as a means of convenience, efficiency, and cost cutting to surgical practice. However, a critical determinant in these benefits is patient selection and safety. The objective of preoperative evaluation is to manage risk – to identify patients who are at low risk, and to reduce these risks at the time of surgery. In some cases the risk of anesthesia is equal to or greater than the surgical procedure at hand. There is no consistent classification of preoperative risk, but particular attention to details of the patient’s history, physical exam, and other diagnostic screening tools can determine whether surgery should be deferred while pre-existing medical conditions are addressed.

The objective of anesthesia is to maintain a state of physiologic homeostasis during the stress of surgery. The physiologic response to surgery is similar to the “fight or flight” response, altering blood flow from non-vital organs to the brain and heart. In order to maintain homeostasis, preoperative determination of cardiac reserve, ability to exchange oxygen, and patient factors which may negatively impact these processes must be known. To this end, the Rule of Threes can simplify the approach to preoperative screening and focus practitioners on the aspects of the history and physical exam which influence patient outcomes in the perioperative period (Table 3.1).2 Exercise tolerance approximates cardiac reserve, and can be approximated using metabolic equivalents (METs). Several studies have demonstrated that the ability to do four or more METs correlates to improved perioperative outcomes. Walking five city blocks, climbing two flights of stairs, running over short distances, and participating in moderate recreational activity (i.e. dancing or golf) without the need to stop for rest is the equivalent of four METs.

Table 3.1 The Rule of Threes

Acute history 1. Exercise tolerance
  2. History of present illness and its treatments
  3. When the patient last visited with his or her primary care physician
Chronic history 1. Medications and causes for their use and allergies
  2. Social history including drug, alcohol, and tobacco use and cessation
  3. Family history and history of prior illnesses and operations
Physical examination 1. Airway
  2. Cardiovascular
  3. Lung, plus those aspects specific to the patient’s condition or planned procedure

From Miller RD. Miller’s anesthesia, 6th edn. New York: Elsevier/Churchill Livingstone, 2005.

As there is no reliable classification system of preoperative risk, a standardized approach to data collection in the preoperative period can facilitate decision making throughout the patient’s course. The initial collection should happen shortly after the decision to proceed with surgery in the surgeon’s office. In addition to medical history pertinent to the specific surgical procedure, a standard set of questions designed to identify risk factors should be answered, such as those found in the Preoperative and Preprocedure Assessment Clinic (PPAC) Form.2 The physical exam should be similarly structured and standardized with some notable additions. Airway assessment is performed according to the Mallampati airway classification based on observations of oral structures visible with tongue maximally protruded, which correlates to ease of intubation (Table 3.2). Additional factors to consider which may limit airway visualization are a short neck, limited cervical spine mobility, poorly mobile or retruded mandible.

Table 3.2 Mallampati airway classification system

I Faucial pillars, soft palate, uvula, tonsillar pillars visualized
II Faucial pillars and soft palate visualized, uvula visualized
III Soft palate, base of uvula visualized
IV Soft palate only

Based on the history and physical, patients are broadly classified according to their medical fitness. The current classification system endorsed by the American Society of Anesthesiology (ASA) is a modification of the Saklad classification developed in the 1940s. Useful more as a global assessment of preop status rather than a measure of risk, the ASA system classifies patients based on the presence of medical illness (Table 3.3).

Table 3.3 ASA classification system

ASA class Medical conditions Common examples
I Healthy, no co-existing medical illness  
II Mild systemic disease with no functional limitation Asthma, hypertension, mild obesity, diabetes (well controlled)
III Severe systemic disease with functional limitation Poorly controlled DM, stable angina, coronary artery disease
IV Severe systemic disease that is a constant threat to life CHF, unstable angina
V Moribund with death expected within 24 hours  

Following a focused history and physical intake, surgeons must then determine the need for additional preoperative screening tests. The tendency of surgeons is to order a large range of ancillary tests, some of which are not necessarily indicated, in an effort to have any conceivable test result available to the anesthesiologist on the morning of surgery. This poses several potential problems. Testing not indicated by medical history may lead to treatment of borderline abnormalities, which may result in patient harm and distress. In addition, since most preoperative abnormalities are not documented in the chart, the failure to investigate abnormal tests is a greater risk of medico-legal liability than the failure to detect it in the first place. Therefore, the guidelines published by the American Society of Anesthesiologists (ASA) summarized in Table 3.4 should be utilized to determine the need for additional preoperative screening tests. In addition, preoperative evaluation should include tests relevant to the type of surgery being performed. For instance, if intraoperative and postoperative bleeding is a significant risk, then a baseline hematocrit should be included in the preoperative work-up.

Table 3.4 Guidelines for preoperative screening tests (based on ASA standards)

Preoperative test Indicated Not necessarily indicated
Electrocardiogram Age >50 with cardiac risk factors Age >50 with no cardiac risk factors
  Pre-existing cardiac or peripheral vascular disease  
  Hypertension  
  Diabetes mellitus  
  Metabolic disease  
Chest radiograph Pre-existing cardiac or respiratory disease Smoking, advanced age, stable cardiac disease, stable COPD, recent URI
  COPD or reactive airway disease  
Complete blood count History of anemia Routine use not indicated
  Hematologic disorder  
  Liver disease  
  More invasive procedures  
Coagulation studies History of bleeding diathesis Routine use not indicated
  Anticoagulant therapy Regional anesthesia (insufficient data)
  Liver disease  
Serum chemistries Endocrine disease Routine use not indicated
  Renal or liver dysfunction  
  Medications affecting serum/urine electrolytes  
Urinalysis Only select procedures (genitourinary procedures) Routine use not indicated
Pregnancy testing Consider in all women of childbearing age  
  Uncertain pregnancy history  

Adapted from American Society of Anesthesiologists. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology 2002;96:485–496.

Based on current practice, patient assessment by the anesthesiologist frequently occurs on the morning of surgery. While adequate for the majority of patients without significant medical co-morbidity or risk factors, there is a select group of patients with significant medical problems or preoperative risk that would benefit from an evaluation well before surgery. It is the role of the surgeon to identify these patients and ensure they receive a focused assessment by an anesthesiologist to minimize their operative risk prior to the morning of surgery (Table 3.5). Failure to do so may result in case cancellation which is frustrating for all parties involved.

Table 3.5 Indications for preoperative anesthesia evaluation prior to day of surgery (based on ASA standards)

General Medical condition prohibits daily activity or necessitates continual assistance
  Hospital admission within 2 months for acute or exacerbation of chronic condition
  Morbid obesity (BMI >30)
Cardiovascular Angina, coronary artery disease, history of myocardial infarction
  Symptomatic arrhythmias
  Poorly controlled hypertension (DBP >110, SBP >160)
  Congestive heart failure
Respiratory COPD or reactive airway disease requiring chronic medication
  Recent COPD or reactive airway disease exacerbation
  History of airway surgery or unusual airway anatomy
Endocrine Diabetes mellitus
  Adrenal disease
  Thyroid disease
  Hepatobiliary disease
Neurological Seizure disorder
  CNS disease

Adapted from American Society of Anesthesiologists. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology 2002;96:485–496 and Pasternak LR. Preoperative screening for ambulatory patients. Anesthesiol Clin North America 2003;21:229–242, vii.

Finally, the decision is made on the method of anesthesia to use. There are a number of factors that influence this decision including medical history, nature of the procedure, length of surgery, facility resources, surgeon’s expertise, anesthesiologist’s expertise, and to some extent, patient preferences.

The specific features of each method for anesthesia will be discussed later in this chapter.

Preoperative medications

Preoperative medication management is an important concept in optimizing patient physiology before they enter the operating theater. Conceptually, this can be viewed as a therapeutic opportunity to minimize preventable risk in an effort to improve patient outcomes. Specifically, the management of medical co-morbidities, patient anxiety, and predictable side effects of surgery and/or anesthetic agents should be addressed to ensure patient comfort throughout the perioperative period and minimize preventable complications.

Maintenance medications

In general, patients undergoing pharmacologic treatment for medical illness should continue taking most of their preoperative medications on the morning of surgery to maintain their steady-state physiology. Examples of such medications include anti-hypertensives, thyroid replacement, medications for symptomatic gastroesophageal reflux, and medications required to optimize pulmonary function (i.e. steroids). Notable exceptions to this guideline are anticoagulants and antiplatelet agents due to the increased risk of bleeding complications as well as oral hypoglycemic medications and insulin which should be adjusted according to blood glucose levels. In patients with more complex medical problems, consultation with a primary care provider is advised to individualize the patient’s needs perioperatively. Herbal supplements should be discontinued, often several days prior to surgery, as many have been shown to affect platelet function. Antidepressants or antianxiety medications can be continued with the exception of monoamine oxidase inhibitors, such as phenelzine (Nardil).

Anxiolytics

Patient anxiety is a significant consideration to address preoperatively for several reasons. The first is physiological. The anxiety associated with the anticipation of surgery, injection of local agents, and being aware of the surroundings during surgery can all have significant hemodynamic effects, which may affect the intraoperative anesthetic medications given during surgery. This potentially increases the incidence of postoperative complications, particularly nausea, vomiting, and blood pressure control. The second consideration is psychological. Anticipation of surgery often evokes psychological symptoms due to alterations in body image, previous traumatic experiences, unrealistic expectations about outcomes, and fear of pain or discomfort. A simple phone call from the surgeon or anesthesiologist on the evening prior to surgery has been shown to reduce this anxiety. Further, psychiatric disorders are not uncommon in the aesthetic population, and the risk of postoperative psychological complications (anxiety, post-traumatic stress, panic attacks) is predicted by their presence preoperatively. In this instance, premedication with an appropriate anxiolytic facilitates a more even psychological state throughout the perioperative period. Notably, in patients with pre-existing psychological disorders, anxiolytics are often continued in the postoperative period. The more common preparations of preoperative anxiolytics include oral valium taken on the morning of surgery (10–20 mg) and Versed IV/IM (2–4 mg) used immediately prior to entering the operating room.

Antiemetics

Postoperative nausea and vomiting (PONV) is a significant problem affecting approximately 30% of patients undergoing surgery with anesthesia, and results in delayed discharge, unplanned hospital admissions, and increased medical cost. In more severe cases, PONV can lead to wound dehiscence, aspiration, hematoma, and severe electrolyte disturbances. Prophylaxis is commonly used to reduce the risk of PONV, and includes the use of serotonin receptor antagonists (i.e. ondansetron), steroids, anticholinergics, benzamides (i.e. reglan), and butyphenones (i.e. droperidol). The specific management of PONV is the subject of a subsequent chapter and will not be discussed here.

Antihypertensives

While relatively hypotensive anesthesia is preferred by many surgical subspecialties, it is of particular importance in aesthetic surgery. Considering the elective and aesthetic nature of this type of surgery, hematoma is a dreaded complication of most procedures and is often correlated to the presence of pre-, intra-, or postoperative hypertension. Antihypertensive agents are used preemptively as the stress of surgery, infiltration, and awareness all may increase blood pressure significantly. Clonidine is a useful drug in this respect, as it reduces sympathetic outflow from the central nervous system, suppresses the peripheral efferent sympathetic pathways, lowers peripheral vascular resistance, and may have sedative effects. Transdermal forms of clonidine are very useful in the postoperative period to prevent hypertension in healthy patients. Alternatively, chlorpromazine (Thorazine) is a major tranquilizer which has a sedative effect while acting to lower blood pressure due to its potent α-antagonist activity.

Methods of anesthesia

Selecting the method of anesthesia is dependent on a number of factors including safety, efficiency, cost, patient preference, surgical expertise, availability of regional or local options, skill of the anesthesiologist, and capability of the facility. Ideally, the method chosen should have a relatively rapid onset, provide adequate amnesia and analgesia to facilitate performing the surgical procedure safely, and have a relatively short and complication-free recovery period. Although general anesthesia remains one of the most common techniques, there is an increasing popularity of local and nerve blocks combined with intravenous sedation (monitored anesthesia care) in the ambulatory setting.

General anesthesia

General anesthesia induces a state of unconsciousness and analgesia through the use of intravenous and inhaled agents, necessitating definitive airway management. It is not simply defined by the presence of an endotracheal tube. Use of general anesthesia in the ambulatory setting must be efficient and cost-effective. Although there is a higher incidence of anesthesia-related side effects when compared to other methods, general anesthesia remains the most widely utilized technique. This requires that specialized equipment, anesthesia machines, and medications are readily available in the facility.

Airway management in general anesthesia is performed using either endotracheal intubation or the laryngeal mask airway (LMA). Endotracheal intubation is the most invasive method and offers the greatest control of the airway, particularly when there are changes in patient positioning intraoperatively. However, aside from these particular instances, there are specific criteria for intubation including airway protection (i.e. in patients at risk for aspiration), maintenance of airway patency, pulmonary toilet, and specific needs to maintain oxygenation (positive pressure ventilation, positive end-expiratory pressure). Endotracheal intubation is associated with a high incidence of postoperative patient complaints including sore throat, cough, and hoarseness.

The alternative is the laryngeal mask airway (LMA), which is halfway between endotracheal intubation and mask anesthesia. The LMA causes minimal cardiovascular responses during insertion, is well tolerated during maintenance anesthesia, provides a relatively secure airway, and results in half as many airway-related complaints postoperatively. The device can also be re-used, frequently in the outpatient setting making it a cost-effective airway solution. However, the LMA does not protect the airway from aspiration, GERD, and upper airway bleeding, so its use is cautioned in patients at risk for these issues. Many anesthesiologists utilize the LMA during rhinoplasty because it acts as a mechanical barrier for blood, preventing it from entering the stomach during surgery which can lead to nausea and vomiting in the postoperative period.

Monitored anesthesia care

Monitored anesthesia care (MAC) is defined as the presence of an anesthesiologist to monitor vital parameters or administer supplemental drugs to patients receiving local anesthesia for surgical procedures. Up to 50% of outpatient procedures could be performed with MAC, reducing the cost of perioperative care up to 80% compared to general anesthesia. The preoperative workup for MAC should be as rigorous as general anesthesia because in a very small fraction of cases, emergent intubation may be required. In general, patients suitable for MAC are cooperative patients who understand that they may be aware during the surgical procedure. These patients should have a favorable airway and are undergoing relatively short procedures (<3 h). Contingent on these parameters is the ability of the surgeon to provide excellent local anesthesia, either via field blocks or specific nerve blockade. MAC is associated with fewer post-anesthesia side effects and more rapid recovery and discharge. The main disadvantage of MAC is lack of airway control, and requires the anesthesiologist to carefully titrate medications to maintain spontaneous respiration while keeping the patient comfortable.

Local anesthesia

Local anesthesia is perhaps the most powerful method of anesthesia, and in skilled hands, is often the only method of anesthesia used. Local agents block nerve conduction by altering sodium conductance in neuron. Precision of placement (nerve blocks) and total dose (field blocks and infiltration) are important determinants in anesthetic effect. Central nervous system and cardiovascular toxicity are the most common serious adverse effects of local anesthetics and are directly related to dose and circulating plasma levels. The more common local agents and their clinical characteristics are listed in Table 3.6.

Table 3.6 Local anesthetic agents

image

Considering the large percentage of plastic surgery procedures that involve the face, mastery of local anesthesia in the face is critical to facilitate patient comfort during a variety of office-based cases. Described eloquently by Zide in 1998,3 complete sensory blockade of the face can be accomplished using eight precisely placed regional nerve blocks (Fig. 3.1) with a minimal volume of anesthetic.

image

Fig. 3.1 Regional nerve blocks in the face. Using eight precisely placed nerve blocks, the face can be completely anesthetized. Circles indicate the entry point of the needle, and arrows indicate the direction of insertion and infiltration.

1. Infraorbital nerve

The infraorbital foramen opens downward and medially, approximately 5–9 mm below the inferior orbital rim in the vertical plane of the medial limbus in forward gaze. This block is approached from in intraoral or percutaneous route between the alar base and nasolabial fold. The needle is inserted pointing towards the medial limbus and advanced until the foramen is entered directly or bony contact is made, at which time the needle is “walked” up the face of the maxilla injecting local anesthetic at points of contact until the foramen is found. Only 1–2 mL of local anesthetic is necessary for complete blockade of the infraorbital nerve. The nasal sidewall, lower lid, cheek, and upper lip (up to but often not including the commissure) are anesthetized using this technique.

2. Mental nerve

The mental nerve exits the foramen below the second mandibular bicuspid as a group of 2–3 fascicles, which arborize quickly to innervate the lower lip, vermillion, and chin. Frequently, manually distracting the lip over the second bicuspid at the level of the gingivobuccal sulcus visually exposes the mental nerve in its submucosal course, allowing for precise intraoral placement of 1–2 mL of local anesthetic. This anesthetizes the lower lip and upper chin, but often does not adequately affect the lower chin due to the deeper course of the lower mental nerve branches and sensory myohyoid nerve. To completely anesthetize the chin, the needle is almost completely withdrawn, redirected in a plane parallel with the face of the anterior mandible, and advanced in a supraperiosteal plane to just beyond the lower border of the mandible. Local anesthesia is deposited (2–3 mL) as the needle is withdrawn, anesthetizing the lower chin. Positioning behind the head of the patient facilitates this maneuver.

3. Supraorbital and supratrochlear nerves

The supraorbital and supratrochlear nerves are blocked using one approach based on their anatomic proximity. While palpating the supraorbital notch with one finger, the brow is distracted laterally with the thumb and the needle is inserted in the middle third of the eyebrow pointed towards the supraorbital notch beneath the corrugator muscles. Local anesthesia is deposited 1 cm prior to the notch, just above the notch, and medially at the nasal bone to include the infratrochlear nerve. The forehead and frontoparietal scalp from the temporal line of fusion to near midline and the medial half of the upper eyelid skin are anesthetized using this technique. It is important to counsel patients prior to this block that some degree of periorbital ecchymosis may occur.

4. Dorsal nasal nerve

The dorsal nasal nerve is a terminal branch of the anterior ethmoid division of the nasociliary nerve supplying the anterior septal mucosa, lateral nasal wall, ala, vestibule, and tip. It exits the nasal vault at the lower border of the nasal bone 5–10 mm lateral to the midline plane. While palating the distal ends of the nasal bones between the thumb and index finger, 1–2 mL of local anesthesia is injected 5–10 mm lateral to midline on both sides.

5. Zygomaticotemporal nerve

One of two distal branches of the zygomatic nerve, the zygomaticotemporal nerve exits a foramen posterior to the lateral orbital rim at or below the level of the lateral canthus to innervate an area posterior to the lateral orbital wall above the level of the canthus back to the hairline and up to the temporal line superiorly. While palpating the zygomaticofrontal suture, the needle is inserted approximately 5 mm inferior to this landmark and is advanced behind the lateral orbital rim to a point 10 mm below the level of the lateral canthus. Local anesthetic is deposited throughout the course of the needle during withdrawal.

6. Zygomaticofacial nerve

The second distal branch of the zygomatic nerve is the zygomaticofacial nerve, which exits via one or several foramina on the anterior surface of the zygoma. After locating the junction of the infraorbital and lateral orbital rim by palpation, 2 mL of local anesthetic is deposited 1–2 cm lateral to this landmark in a supraperiosteal plane anesthetizing a triangular area centered on the cheek prominence with the apex oriented inferiorly ending at the lower border of the anterior ramus of the mandible.

7. Great auricular nerve

The great auricular nerve emerges from behind the sternocleidomastoid muscle and continues superiorly along its surface to innervate the lower half of the ear, postauricular skin, and variable regions overlying the mandibular angle up to the tragus. The landmark for injection is located along a line 6.5 cm inferior from the external acoustic meatus that intersects the mid-axis of the sternocleidomastoid muscle. Local anesthetic is deposited on the anterior fascial surface of the muscle.

8. Mandibular division of the trigeminal nerve (V3)

The mandibular division of the trigeminal nerve innervates the majority of the cheek and pretragal regions, and is accessed via spinal needle through the sigmoid notch 1 cm posterior to the pterygoid plate. The sigmoid notch is palpated externally approximately 2.5 cm anterior to the tragus as the patient opens and closes the mouth. A small amount of superficial anesthetic is deposited here to account for a larger needle. Next, a 22-gauge spinal needle is inserted through the anesthetized area in a plane perpendicular to the face and advanced until contact with the pterygoid plate, taking note of how deep the needle has been advanced (usually around 4 cm, a plastic slide is useful in this capacity). The needle is then almost completely withdrawn, redirected to a point 1 cm posterior to the initial point of contact, and then advanced to the same depth measured previously. Following aspiration, 3–4 mL of local is deposited to numb the cheek area.

Office-based anesthesia

The concept of a surgeon operating from an office setting has been routinely practiced over several decades, but the recognition of office-based anesthesia (OBA) as a subspecialty of anesthesia is only a recent development. OBA is technically defined as the administration of anesthesia in a facility not licensed as an ambulatory surgery center, which operates and is integrated into the daily operations of a surgeon’s office. Practically speaking, there is a broad range of procedures which utilize OBA, from very minor surgical procedures, to much more invasive procedures. The level of surgical complexity that can be performed in this setting are highly dependent on the surgeon’s skill and level of comfort with the procedure. Regardless, patient selection is a critical factor in maintaining the efficiency, convenience, and cost-effectiveness of office-based procedures, and the standards of our specialty are outlined in a task force statement from the American Society of Plastic Surgeons (ASPS).4 The basic clinical requirements for safe OBA can be summarized using the pneumonic POSEMED (Table 3.7).5

Table 3.7 Requirements for safe office-based anesthesia

Positive pressure ventilation Small anesthesia machine or bag-mask apparatus
Oxygen Gas line or cylinders
Suction One unit with a backup
Emergency equipment Airway supplies, defibrillator, crash cart
Monitors Electrocardiogram, blood pressure, pulse oxymetry
Drugs ACLS/resuscitative agents, anesthetic agents, dantrolene

According to the ASPS, plastic surgery performed under anesthesia other than minor local with minimal oral tranquilization should be performed in a facility that is accredited by a national or state-recognized agency (such as the American Association for Accreditation of Ambulatory Surgery Facilities (AAAASF), the Accreditation Association for Ambulatory Health Care (AAAHC), or the Joint Commission on Accreditation of Healthcare Organizations (JCAHO)), certified to participate in the Medicare program under Title XVIII, or licensed by the state the facility is located in.6 Accreditation in OBS affords several advantages to surgeons, including facility fee acquisition, regulation compliance, and a marketing advantage to patients familiar with office-based surgery. Reflecting the growing popularity of OBA, each accrediting agency has begun to tailor their criteria to smaller facilities to reduce the cost and administrative burden of accreditation.

Intraoperative considerations

Positioning

Positioning and padding the patient in the operating room is often overlooked in the busy perioperative period. Anesthetized patients lack the normal defense mechanisms from pressure-induced injury, and are at risk for nerve, vessel, joint, and skin injury. Particularly in body contouring and breast procedures where several position changes are characteristic, attention to detail in orienting and padding the patient are required. According to the ASA Closed Claims Database (1970–1995), nerve damage (16%) was second only to death (32%) in the nature of liability claims settled with ulnar neuropathy and brachial plexus injuries being the most frequent.7 As a result the ASA issued a practice advisory for the prevention of perioperative neuropathies, detailing the specific recommendations related to upper extremity, lower extremity, and padding (see summary in Miller2).

Thermoregulation

Maintenance of thermal steady state requires that dissipative heat loss is balanced by heat production. During surgery, excessive heat loss and redistribution of heat from the core to peripheral tissues contributes to mild core hypothermia. Even mild levels of hypothermia (up to 3°C) can contribute significantly to surgical outcomes, increasing morbidity of cardiac outcomes, decreased resistance to surgical wound infections, impaired coagulation, and decreased postoperative comfort. Prospective randomized studies have demonstrated that mild intraoperative hypothermia is associated with delayed wound healing, prolonged hospitalization, and a 3-fold increase in the incidence of wound infection.8

Thus, in order to maintain steady state during surgery accurate core thermal monitoring must be used to identify thermal losses, while making an effort to minimize dissipative heat losses and supplementing heat production. Examples of heat supplementation include heated airway humidifiers, forced air warmers and blankets, and passive heat and moisture exchangers. For surgical procedures less than 60–90 minutes in length, forced warming devices are not likely to be cost-effective measures.

Fluid management

Optimizing cardiac function and oxygen delivery as well as maintaining electrolyte balance are the primary goals of intraoperative fluid management. For many aesthetic procedures, fluid management is relatively straight forward, balancing maintenance requirements with pre-existing, surgical, and insensible losses. However, there are several procedures where fluid management becomes more complicated. Liposuction is one such instance where large fluid volumes are instilled subcutaneously, allowed to dwell, then partially aspirated along with subcutaneous fat. Based on the volume of aspirate, there are specific resuscitation guidelines which should guide surgeons to maintain euvolemia in the perioperative period.

Postoperative considerations

Postoperative recovery is defined by three overlapping phases: early, immediate, and late recovery. Early recovery (phase I) describes the patient during emergence from anesthesia which begins with the discontinuation of anesthetic agents. During this phase, patients regain protective airway reflexes and motor function. Throughout early recovery, patients are assessed for criteria for discharge from the recovery room according to the Aldrete scoring system, which incorporates voluntary movement, respiration, circulation, consciousness, and oxygen saturation.9 After attaining an adequate score, patients can be moved out of the recovery room to intermediate recovery (phase II), where they are prepared for discharge. With the development of shorter acting anesthetic regimens, the concept of “fast tracking” has emerged as a cost effective means of recovery. Typically, these patients achieve an adequate Aldrete score upon entering the recovery room, and can safely be moved to phase II saving valuable recovery room resources. However, the Aldrete scoring system does not account for postoperative emesis and pain, the two main contributors to delayed discharge. As a result, White proposed a modified scoring system to determine a patient’s eligibility for fast-track status.10 Late recovery (phase III) occurs after discharge from the facility when patients return to their preoperative physiologic state.

During phase II, the evaluation of patient suitability for discharge often is passed from the anesthesiologist to the practitioners staffing the unit. Standardized criteria are used to ensure patient safety and determine home readiness, and include vital signs, ambulation, nausea and vomiting, pain, and surgical bleeding. On average, patients meet these criteria within 1–2 hours of surgery.11 The ability to tolerate oral intake is not a requirement for discharge, and patients should not be forced to drink liquids postoperatively; oral intake has not been shown to influence the incidence of nausea and vomiting. Routinely requiring patients to void postoperatively should also be avoided, unless the ability to void is an integral part of the surgical procedure.

Complications

The most frequent post-anesthetic complications such as nausea, vomiting, pain, and cardiovascular instability should be anticipated and addressed in the pre- and intraoperative periods to minimize the risk of patients developing issues in the recovery phase. Other common complications related to airway irritation (hoarseness, cough) are minor and will resolve spontaneously.

Malignant hyperthermia (MH) is a potentially life-threatening complication of anesthesia that requires the availability of specific pharmacologic agents to treat a severe crisis. MH is a subclinical myopathy triggered by volatile inhalational agents or succinylcholine which manifests as a hypermetabolic state of tachycardia, hypercarbia, acidosis, rigidity and fever. Genetically linked to mutations in the RYR1 gene, MH can occur in patients with a family history or with no history at all. Onset can be rapid, occurring intraoperatively or in the postoperative period and should be rapidly identified and treated with dantrolene. Because of the potentially fatal outcomes of MH, all office and ambulatory centers that utilize inhalational agents or succinylcholine should be equipped with an adequate supply dantrolene to treat a fulminant malignant hyperthermic crisis.

Pearls & pitfalls

Pearls

• The objective of anesthesia is to maintain a state of physiologic homeostasis during the stress of surgery.

• Several studies have demonstrated that the ability to do four or more metabolic equivalents (METs) correlates to improved perioperative outcomes.

• Preoperative medication management is an important concept in optimizing patient physiology before they enter the operating theater.

• While relatively hypotensive anesthesia is preferred by many surgical subspecialties, it is of particular importance in aesthetic surgery.

• Although general anesthesia remains one of the most common techniques, there is an increasing popularity of local and nerve blocks combined with intravenous sedation (monitored anesthesia care) in the ambulatory setting.

• Local anesthesia is perhaps the most powerful method of anesthesia, and in skilled hands, is often the only method of anesthesia used.

• Complete sensory blockade of the face can be accomplished using eight precisely placed regional nerve blocks with a minimal volume of anesthetic.

• The recognition of office-based anesthesia (OBA) as a subspecialty of anesthesia is a recent development.

Pitfalls

• Preoperative evaluation is to manage risk – to identify patients who are at low risk, and to reduce these risks at the time of surgery. In some cases the risk of anesthesia is equal to or greater than the surgical procedure at hand.

• Preop testing not indicated by medical history may lead to treatment of borderline abnormalities, which may result in patient harm and distress.

• There is a select group of patients with significant medical problems or preoperative risk that would benefit from an evaluation well before surgery.

• Postoperative nausea and vomiting (PONV) is a significant problem affecting approximately 30% of patients undergoing surgery with anesthesia.

• The laryngeal mask airway (LMA) does not protect the airway from aspiration, GERD, and upper airway bleeding, so its use is cautioned in patients at risk for these issues.

• Malignant hyperthermia (MH) is a potentially life-threatening complication of anesthesia that requires the availability of specific pharmacologic agents to treat a severe crisis.

References

1. Waters R. The downtown anesthesia clinic. Am J Surg. 1919;33(Suppl):71–73.

2. Miller RD. Miller’s anesthesia, 6th edn. New York: Elsevier/Churchill Livingstone; 2005.

3. Zide BM, Swift R. How to block and tackle the face. Plast Reconstr Surg. 1998;101:840–851.

4. Iverson RE, Lynch DJ. Patient safety in office-based surgery facilities: II. Patient selection. Plast Reconstr Surg. 2002;110:1785–1790. discussion 1791–1792 –

5. Koch ME, Dayan S, Barinholtz D. Office-based anesthesia: an overview. Anesthesiol Clin North America. 2003;21:417–443.

6. Iverson RE. Patient safety in office-based surgery facilities: I. Procedures in the office-based surgery setting. Plast Reconstr Surg. 2002;110:1337–1342. discussion 1343–1346 –

7. Cheney FW, Domino KB, Caplan RA, Posner KL. Nerve injury associated with anesthesia: a closed claims analysis. Anesthesiology. 1999;90:1062–1069.

8. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. N Engl J Med. 1996;334:1209–1215.

9. Aldrete JA. The post-anesthesia recovery score revisited. J Clin Anesth. 1995;7:89–91.

10. White PF, Song D. New criteria for fast-tracking after outpatient anesthesia: a comparison with the modified Aldrete’s scoring system. Anesth Analg. 1999;88:1069–1072.

11. Chung F, Chan VW, Ong D. A post-anesthetic discharge scoring system for home readiness after ambulatory surgery. J Clin Anesth. 1995;7:500–506.

12. American Society of Anesthesiologists. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology. 2002;96:485–496.

13. Pasternak LR. Preoperative screening for ambulatory patients. Anesthesiol Clin North America. 2003;21:229–242. vii

Related posts:

Aesthetic facial microsurgery Mastopexy with and without augmentation Nipple–areola reconstruction Botox® for face, neck and brow Secondary rhinoplasty Periareolar Benelli mastopexy and reduction: The “Round Block”