Most outpatient cosmetic procedures are now performed in surgeons’ offices, with patients under local anesthesia and minimal intravenous sedation. Sedation at any level beyond minimal creates the risk of airway obstruction and ventilatory depression, which can result in irreversible brain injury or death within minutes. This article discusses appropriate patient and procedure selection, and outlines the personnel, equipment, and techniques necessary to avoid such outcomes.
Key points
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Most cosmetic procedures are performed in outpatient surgical facilities with intravenous sedation, which may result in ventilatory depression and airway obstruction.
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Ventilatory and airway complications are a major factor in sedation-related adverse outcomes, such as death or anoxic brain injury.
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Appropriate patient and procedure selection may prevent ventilatory and airway-related complications.
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Preoperative patient evaluation may help identify patients at risk for airway complications but cannot rule out an unexpected difficult airway.
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All anesthetics should be administered by, or medically directed by, an anesthesiologist.
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The use of supplemental oxygen during sedation for procedures on the head, face, or neck creates a fire hazard.
Introduction
The type of airway management provided depends on the anesthetic technique and the type of anesthetic technique provided depends on the procedure. Although most outpatient cosmetic procedures are performed under minimal-to-moderate sedation with local anesthesia, certain procedures require deep sedation or general anesthesia for patient comfort and cooperation. Occasionally, general anesthesia may be safer than deep sedation, especially in patients at risk for ventilatory or airway problems.
Sedation may be regarded as a continuum ( Table 1 ) with the need for active airway management typically increasing as the depth of sedation increases. Progression along this continuum is associated with diminished protective reflexes, including those that maintain ventilation, circulation, and airway patency and protection. Although the intention is to maintain one level of sedation, there is always the risk of progressing to the next level. Because of this risk, the anesthesia provider must be proficient in airway management commensurate with the level of sedation beyond that which is anticipated. The combination of a trained provider, appropriate patient and procedure selection, vigilance, and adherence to monitoring standards, can minimize anesthesia complications.
| Minimal Sedation (Anxiolysis) | Moderate Sedation and/or Analgesia (Conscious Sedation) | Deep Sedation and/or Analgesia | General Anesthesia | |
|---|---|---|---|---|
| Responsiveness | Normal response to verbal stimulation | Purposeful ∗ response to verbal or tactile stimulation | Purposeful ∗ response following repeated or painful stimulation | Unarousable even with painful stimulus |
| Airway | Unaffected | No intervention required | Intervention may be required | Intervention often required |
| Spontaneous Ventilation | Unaffected | Adequate | May be inadequate | Frequently inadequate |
| Cardiovascular Function | Unaffected | Usually maintained | Usually maintained | May be impaired |
∗ Reflex withdrawal from a painful stimulus is not considered a purposeful response.
Introduction
The type of airway management provided depends on the anesthetic technique and the type of anesthetic technique provided depends on the procedure. Although most outpatient cosmetic procedures are performed under minimal-to-moderate sedation with local anesthesia, certain procedures require deep sedation or general anesthesia for patient comfort and cooperation. Occasionally, general anesthesia may be safer than deep sedation, especially in patients at risk for ventilatory or airway problems.
Sedation may be regarded as a continuum ( Table 1 ) with the need for active airway management typically increasing as the depth of sedation increases. Progression along this continuum is associated with diminished protective reflexes, including those that maintain ventilation, circulation, and airway patency and protection. Although the intention is to maintain one level of sedation, there is always the risk of progressing to the next level. Because of this risk, the anesthesia provider must be proficient in airway management commensurate with the level of sedation beyond that which is anticipated. The combination of a trained provider, appropriate patient and procedure selection, vigilance, and adherence to monitoring standards, can minimize anesthesia complications.
| Minimal Sedation (Anxiolysis) | Moderate Sedation and/or Analgesia (Conscious Sedation) | Deep Sedation and/or Analgesia | General Anesthesia | |
|---|---|---|---|---|
| Responsiveness | Normal response to verbal stimulation | Purposeful ∗ response to verbal or tactile stimulation | Purposeful ∗ response following repeated or painful stimulation | Unarousable even with painful stimulus |
| Airway | Unaffected | No intervention required | Intervention may be required | Intervention often required |
| Spontaneous Ventilation | Unaffected | Adequate | May be inadequate | Frequently inadequate |
| Cardiovascular Function | Unaffected | Usually maintained | Usually maintained | May be impaired |
∗ Reflex withdrawal from a painful stimulus is not considered a purposeful response.
Preoperative planning
Staff and Equipment
Administration of any level of sedation, ranging from moderate sedation through general anesthesia, requires a commensurate proficiency in airway management and the equipment and supplies to execute it. The American Society of Anesthesiologists (ASA) guidelines for ambulatory anesthesia and office-based anesthesia recommend that anesthesia beyond the level of moderate sedation be administered by anesthesiologists, or be medically directed by an anesthesiologist if administered by an anesthesia resident, a certified registered nurse anesthetist, or an anesthesia assistant. The ASA strongly recommends that, when an anesthesiologist is not available, non-physician anesthesia providers must be medically supervised by a licensed physician. The medically supervising physician should be specifically trained in moderate or deep sedation as well as airway, ventilation, and circulation rescue techniques (ie, management for one sedation level beyond that which is intended). Specific sedation training for medical supervision is critical in office-based practices where hospital-based emergency backup is not immediately available.
Patients receiving moderate sedation are usually able to maintain a patent airway without assistance. Although supplemental oxygen may not be necessary, it should be available. Airway equipment for moderate sedation includes an oxygen source, nasal cannulas, suction catheters, oral and nasopharyngeal airways, and a means to administer positive pressure ventilation, such as a mask and artificial manual breathing unit (AMBU) bag. Deep sedation increases the risk of ventilatory depression and airway compromise, so additional equipment must be available, including laryngoscopes, an assortment of several sizes of endotracheal tubes (ETTs), laryngeal mask airways (LMAs), and emergency surgical airway kits. The postanesthesia care unit should be outfitted similarly, based on the level of sedation performed intraoperatively and the need for postoperative sedation and analgesia.
Monitors should include pulse oximetry, ventilation (capnography or capnometry, ventilatory rate monitor), noninvasive blood pressure, continuous ECG, and temperature. A defibrillator and an emergency cart fully stocked with resuscitation drugs and equipment should be readily available and the recovery room should be staffed by qualified nurses or other trained personnel. Policies and protocols should be in place to respond to emergencies and to expedite patient transfers to an acute care hospital for extended care.
Preoperative Fasting
Any level of sedation beyond minimal creates the potential for airway instrumentation. Preoperative fasting requirements must be observed before elective surgical procedures, except those performed with minimal sedation or without sedation. The ASA recommendations for preoperative fasting are given in Table 2 .
| Food Ingested | Minimum Fasting Time Before Anesthesia |
|---|---|
| Clear liquid | 2 h |
| Human milk | 4 h |
| Infant formula, nonhuman milk | 6 h |
| Light meal (eg, clear liquid + toast or cereal) | 6 h |
| Meat or fat-containing food | 8 h |
History and Physical Examination
The use of sedation may lead to an airway emergency, particularly if risk factors for a difficult airway have not been recognized preoperatively. The patient history can elicit past problems with anesthesia including difficulties with airway management. The physical examination may help identify a combination of features predictive of both airway and ventilatory complications. In outpatient settings, airway evaluation may identify patients with an obvious or probable difficult airway, the management of which may require above-average expertise and skills, advanced techniques, expert assistance, and special equipment.
Predicting a difficult airway is simple only in a patient with a history of a difficult intubation, or with an obvious anatomy that suggests a difficulty. In other cases, a difficult airway is detected by recognizing a combination of subtle physical risk factors during an airway-focused physical examination ( Box 1 ).
Transoral view of the posterior pharynx (Mallampati classification)
Range of motion of the cervical spine
Thyromental distance
Range of mouth opening
Mandibular protrusion test
Neck anatomy
Presence of a beard
Dentition
According to the Mallampati classification (modified by Samsoon and Young ) there are four grades of visualization of the posterior pharyngeal structures, with classes 3 and 4 associated with a difficult exposure of the larynx during direct laryngoscopy or difficult mask ventilation ( Fig. 1 ). Full extension at the atlanto-occipital joint should be at least 35° ( Fig. 2 ). Cervical range of motion may be limited by previous trauma, surgical procedures, scarring from burns or radiation therapy, or a degenerative disease of the spine. Thyromental distance, from the mentum of the mandible to the superior margin of the thyroid cartilage, should be at least 6 cm or three average fingerbreadths ( Fig. 3 ). Mouth opening is the measure of the distance between upper and lower incisors (or gingivae) and should be at least three fingerbreadths ( Fig. 4 ). The mandibular protrusion test is normal if lower incisors can be protruded anterior to the upper incisors. It is limited in patients with a receding mandible (micrognathia) and overbite or limited mobility of the temporomandibular joint ( Fig. 5 ). Neck anatomy may be significant for masses and motion-limiting scars or contractures and a short and thick neck may be associated with obstructive sleep apnea (OSA). A full beard interferes with mask ventilation because it prevents a tight seal between the mask and the face, and is often associated with micrognathia. Dentition should be inspected for the presence of removable dentures and loose teeth. Features that may interfere with laryngoscopy and intubation, especially when combined with other risk factors for a difficult airway, include protruding upper incisors, large upper crowns, or an oversized upper bridge (see Fig. 5 ). Earlier chin implants and genioplasties may produce a false thyromental distance and underestimation of the difficulty of maintaining an airway.
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