Chapter 12. Conscious Sedation Techniques in Plastic Surgery
John B. Hijjawi, MD, FACS; Thomas A. Mustoe, MD
As operative techniques in plastic surgery become more refined and predictable, the ability of a surgeon to provide an overall pleasant patient experience is increasingly expected by patients. Providing a pleasant and safe “patient experience” is dependent not only on the surgeon’s technical ability with the scalpel, but indeed on their ability to minimize perioperative and postoperative pain, anxiety, nausea, vomiting, and expense, all in the context of uncompromising patient safety.
The unique nature of most plastic surgery procedures, occurring largely in subcutaneous or submuscular planes, provides an ideal opportunity for the surgeon to exploit knowledge of cutaneous patterns of innervation, thus establishing very satisfactory regional sensory blockade. Combining techniques of regional blockade, which often involve local anesthesia delivery in the form of “tumescent anesthesia,” with conscious sedation allows the surgeon to perform procedures safely without forcing the patient to submit to general anesthesia.
There has been an increasing trend toward outpatient surgery over the past two decades, whether done in the hospital or surgicenter setting. There have been substantial improvements in the techniques of general anesthesia that have allowed more rapid recovery, but there are still disadvantages to general anesthesia, including the risks inherent in induction, intubation, blood stasis in the extremities, and extubation, as well as the nausea and postanesthesia “hangover.”
Achieving effective local anesthesia is the foundation of safe conscious sedation or deep sedation, making this anesthetic technique applicable to the full range of aesthetic surgery and breast surgery, as well as facilitating many reconstructive procedures. As suggested, such techniques do not rely on the use of sedative or analgesic medications to make painful surgical procedures tolerable. Rather, relatively moderate amounts of opioid and benzodiazepines are used to make the infiltration of high-volume, dilute lidocaine solution tolerable. The resultant surgical field anesthesia makes the ensuing procedure tolerable.
Plastic surgeons have accepted the dual responsibilities of providing both surgical and anesthesia care in office situations for some time. Despite the ready availability of dedicated anesthesia care, a large segment of plastic surgeons performing high-volume aesthetic surgery choose to combine local anesthesia with surgeon-directed conscious sedation about a third of the time. An American Society of Plastic Surgeons study found that in 2007 more than 80% of cosmetic surgery procedures did not occur in hospital settings. As a result, all plastic surgeons should be familiar with conscious sedation whether they pursue these techniques or opt for anesthesiologist-directed care in all cases.
Currently, in Illinois and Florida, deep sedation in an office setting is restricted without the presence of an anesthesiologist. Furthermore, in Illinois, conscious sedation in an office setting is restricted to those situations in which the surgeon is supervising a certified registered nurse anesthetist (CRNA). In a hospital or surgicenter setting where anesthesia support is readily available, surgeon-directed conscious sedation without a CRNA is permitted.
DISTINGUISHING CONSCIOUS SEDATION FROM DEEP SEDATION
Conscious sedation is routinely provided by nonanesthesiologists in situations such as colonoscopy, bronchoscopy, and dental, emergency room, and interventional radiology procedures. During conscious sedation, patients preserve the ability to maintain a patent airway independently and continuously, and remain capable of responding purposefully to verbal and tactile commands. This provides the added benefit of maintaining the patient’s ability to cooperate with simple tasks, such as changing positions. This can be extremely beneficial in procedures such as liposuction where several position changes may be necessary. At no point is the patient’s spontaneous ventilation or airway patency impaired. Sedation may or may not be combined with analgesic medications and local anesthesia depending on the nature of the procedure to be performed. Unlike deep-sedation protocols, no interventions are required to maintain airway patency, spontaneous ventilation, or hemodynamic stability. Accordingly, it is imperative that dedicated nursing personnel continuously monitor the patient’s state of alertness and communicate that to the surgeon, along with the patient’s vital signs, including oxygen saturation.
Recall of the procedure is generally limited or nonexistent. Hasen has compared surgeon-directed conscious-sedation techniques to anesthesiologist-directed deep-sedation techniques in patients undergoing aesthetic surgery procedures. That analysis revealed no difference in patient recall of painful events or anxiety during surgery. Significantly more fentanyl was required in the cases performed under a deep-sedation technique (typically with anesthesia-directed propofol infusion) relative to those performed under a surgeon-directed conscious-sedation technique. As would be expected in patients receiving more fentanyl, the deep-sedation group experienced significantly more postoperative nausea and vomiting.
A critical component of successful conscious sedation for surgical procedures is the ability to achieve adequate local anesthesia through a combination of wetting solutions (dilute preparations of lidocaine and epinephrine) and nerve blocks, thus limiting the amount of opioid analgesia required for a given procedure.
Deep Sedation
The spectrum continues into deep sedation where the patient experiences a partial loss of protective airway reflexes and becomes unable to respond purposefully to verbal stimulation. Some assistance may be needed to maintain airway patency and spontaneous ventilation. The patient’s responses may be limited to reflex withdrawal from painful stimuli. Cardiopulmonary function may become depressed as the patient proceeds along the spectrum from deep sedation to general anesthesia.
“Overshooting” when attempting to achieve conscious sedation results in the patient progressing to deep sedation. As discussed, this means that the patient typically will require some verbal or tactile stimulation to continue breathing spontaneously. Additionally, the patient may require supplemental oxygen. We have been able to avoid giving reversal agents, although they are always immediately available as a backup maneuver.
In contrast, “overshooting” when a deep sedation protocol is being carried out typically results in complete cessation of any respiratory drive as the patient is already in a state of significantly depressed ventilation as part of the deep sedation state. This becomes especially problematic because deep sedation protocols are typically carried out with propofol, which, while metabolized in relatively short order, has no available reversal agent.
As a result, a significantly higher level of training is required of the individual delivering medications and monitoring the patient when a deep sedation protocol is pursued. Rather than a registered nurse with additional in-hospital training, a CRNA or anesthesiologist must be present for any deep-sedation protocol.
General Anesthesia
In general anesthesia there is a complete loss of protective reflexes accompanied by an inability to independently maintain a patent airway or spontaneous ventilation. Deeper states of general anesthesia are associated with depressed cardiovascular function. Conscious sedation, as noted, is routinely directed by nonanesthesiologists. However, deep sedation and general anesthesia is strictly limited to anesthesiologists or CRNAs under the direction of a surgeon or, more commonly, an anesthesiologist.
PROCEDURE SELECTION
A common misconception regarding the use of conscious sedation is that the technique is geared exclusively toward aesthetic surgery patients as a means to decrease the total cost of procedures. Consequently, many would assume that conscious-sedation techniques are not used for reconstructive procedures where insurance is involved. On the contrary, we routinely use conscious-sedation techniques in aesthetic, reconstructive, and combined procedures.
The most common reconstructive procedures for which we employ conscious sedation include contralateral symmetry procedures after unilateral breast reconstruction; secondary breast procedures, such as expander-implant exchanges; autologous fat grafting for contour refinement; and secondary recontouring of implant or autologous breast reconstructions. Expanding the application of this technique to include reconstructive procedures can be an invaluable opportunity for those gaining experience with conscious sedation.
Aesthetic procedures, including rhytidectomy, brow-lift, blepharoplasty, and limited liposuction, have routinely been performed under conscious sedation in office and hospital settings for years. In addition to these more traditional procedures, conscious sedation has evolved into our procedure of choice for abdominoplasty, liposuction, both submuscular and subglandular breast augmentation, and mastopexy or limited breast-reduction procedures.
The critical factor that makes the safe execution of all of these procedures possible under conscious sedation is the ability to achieve effective local anesthesia. Essentially, in healthy patients, conscious sedation can be safely utilized in any procedure or combination of procedures in which effective local anesthesia can be achieved with an upper-limit lidocaine dose of 35 mg/kg (delivered using a tumescent technique), given an operative duration of less than approximately 5 hours.
PATIENT SELECTION
Medical Status
It is a firm plastic surgery principle that properly selected patients with realistic expectations prior to surgery are patients who will most likely be satisfied with the results of plastic surgery procedures. The same holds true for the patient’s anesthesia experience, an increasingly crucial factor in their overall satisfaction. Properly selecting the method of anesthesia for a given patient and clearly communicating to the patient what they can expect are important factors in a safe, successful, and pleasant surgical experience for the patient and surgeon alike.
Patients who are candidates for conscious sedation must be scored as American Society of Anesthesiology (ASA) Class I or II. More recently, Physical Status Classifications have been used to stratify patients into risk-based categories. Within the Physical Status (PS) Classification, conscious-sedation techniques are limited to those patients qualifying as a PS-1 or PS-2. This limits conscious sedation to either healthy patients or patients with mild systemic diseases resulting in no functional limitations (ie, well-controlled hypertension or diabetes, mild obesity). Particular attention is paid to preoperative electrocardiograms and cardiac status as indicated by a patient’s functional status.
Relative contraindications to conscious sedation include either extremely young or old patients, a history of heavy smoking, or significant cardiopulmonary, hepatic, renal, or central nervous system (CNS) disease. This technique is not appropriate for those with a significant history of alcohol or illicit drug use, patients who are morbidly obese, have sleep apnea or atypical airway anatomy, or a prior history of complications related to sedation or general anesthesia.
Beyond Medical Issues
Simply meeting specific medical requirements does not make a given patient an optimal candidate for conscious sedation. Patients who are highly motivated to avoid a general anesthetic for any reason and are reasonably comfortable with the idea of undergoing a surgical procedure make ideal candidates for conscious sedation. In contrast, the patient who is extremely anxious about undergoing a procedure, is adamant that they want to be completely unaware of the procedure, or has had a negative experience with a previous sedation is probably best treated with a general anesthetic or anesthesiologist-monitored deep-sedation protocol.
Gottlieb has discussed the concept of the “comfort zone” in regard to a surgeon’s comfort level not only with a particular procedure but also with a given patient. A procedure that is considered technically routine in one patient may be much more challenging in another patient. For example, a free deep inferior epigastric perforator (DIEP) breast reconstruction in a healthy patient may be a straightforward case for a given surgeon, well within that surgeon’s “comfort zone.” Add a significant smoking history, obesity, and small perforators to the picture, and that same surgeon may be entirely uncomfortable with the procedure.
This concept is equally important in assessing a patient’s appropriateness for a conscious sedation approach to surgical anesthesia. Patients with high levels of anxiety or those undergoing relatively long procedures may make even a surgeon experienced with conscious sedation uncomfortable with anything short of a general anesthetic or deep sedation technique. It is particularly important to recognize this while gaining experience with conscious sedation. If a given patient pushes the limits of a surgeon’s “comfort zone” with conscious sedation, it is safest to opt for anesthesiologist-directed care. As experience with conscious sedation is gained, each surgeon’s “comfort zone” will subsequently grow in a broader range of patients and procedures.
PREOPERATIVE EVALUATION
Preoperative evaluation of conscious sedation candidates includes a thorough history and physical, age-appropriate lab testing, electrocardiography and radiographic evaluation, and consultation with appropriate medical specialists. Healthy patients younger than 40 years of age require no specific laboratory evaluation short of pregnancy testing in females uncertain of their pregnancy status. Between 40 and 65 years of age, a preoperative hemoglobin and electrocardiogram are obtained. Patients older than 65 years of age should also have a preoperative chest radiograph review.
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