Anesthesia Techniques: Which is the Safest Choice?

Richard D. Urman

Fred E. Shapiro

As anesthesia providers, we are often asked two simple questions:

What type of anesthesia would you recommend?
Which is the safest choice?

After reading this chapter, the reader will understand that these questions are not easy to answer.

The discussion concerning anesthetic safety in the office has been divided into two parts. The goal is to discuss a variety of anesthetic techniques that can be employed in an office setting, followed by a discussion of safety issues surrounding office-based anesthesia (OBA) practice. The chapter will conclude with a brief overview of the most recent literature addressing OBA safety.

THE CHOICE OF ANESTHESIA

It is important to realize that the same anesthetic techniques that are used in acute care hospitals and ambulatory surgical centers can be used in an office-based setting. The four broad categories are:

Local anesthesia
Monitored anesthesia care (MAC)
Regional anesthesia
General anesthesia

Techniques involving a combination of two or more of the anesthetic types have also been successfully used in the office. The anesthetic techniques are:

Local Anesthesia

This technique provides a loss of sensation to an area of the body. It is often used as the only anesthetic for a variety of procedures. Dermatologists, dentists, gastroenterologists, and surgeons have successfully used local anesthesia without the need for an anesthesiologist. Local anesthesia can also be used as an adjunct to monitored or general anesthesia, as well as for postoperative pain control.

Monitored Anesthesia Care

This technique involves the administration of medications that produce sedation and relieve pain. During the surgery, the patient’s vital signs, which include the heart rate, blood pressure, respiratory rate, and oxygen level, are monitored in order to maintain stability and avoid sudden changes or complications. According to the American Society of Anesthesiologists (ASA), MAC may include varying levels of sedation, analgesia, and anxiolysis. Refer to the ASA guidelines regarding MAC anesthesia listed in the subsequent text.

Regional Anesthesia

Regional anesthesia techniques have been successfully used in office settings, and include spinal, epidural, and extremity nerve blocks. Spinal or epidural blocks are useful as sole anesthetics or can be employed in conjunction with MAC or general anesthesia. Various upper and lower extremity blocks can provide excellent intra- and postoperative analgesia.

General Anesthesia

This involves the loss of consciousness, lack of pain sensation, and purposeful response to stimuli. General anesthesia can be provided safely in the office by the anesthesiologist as long as proper equipment and monitoring are available (see Chapter 5).

Clearly, the choice of the anesthetic technique largely depends on the patient’s medical condition, type of operation, as well as skills and training of the personneladministering anesthesia.

There is a fine line between sedation, deep sedation, and general anesthesia. Consumption of alcohol, recreational drug use, sensitivity to pain, and unusual reactions to medication (sometimes people have a decreased, increased, or opposite effect of what the drug is intended to do or perhaps an allergic reaction to a drug) may be crucial factors determining the most safe anesthetic technique for any particular patient.

An anesthetic plan ideally should be formulated before the patient’s arrival to the office for surgery, after resolving any medical issues, and after having completed the necessary preoperative workup. These standards are the same regardless of the site where anesthesia is being administered.

The ASA Guidelines for Office-Based Anesthesia (1), which were last reaffirmed by the House of Delegates in 2004, outline the recommendations regarding clinical care and patient and procedure selection (see Box 7.1).

Box 7.1

Clinical Care Patient and Procedure Selection

The anesthesiologist should be satisfied that the procedure to be undertaken is within the scope of practice of the health care practitioners and the capabilities of the facility.
The procedure should be of a duration and degree of complexity that will permit the patient to recover and be discharged from the facility.
Patients who by reason of pre-existing medical or other conditions may be at undue risk for complications should be referred to an appropriate facility for performance of the procedure and the administration of anesthesia.

Office-based surgery can offer medical care in a convenient, comfortable, and affordable environment. It is important to have the patient involved in the planning and delivery of care. Being informed and asking the right questions before undergoing an office-based procedure will insure safe, high-quality care tailored to the patient’s individual needs. This means that there might be times when a person is not a good candidate to have surgery in a doctor’s office. An example is a patient with severe chronic lung disease, or heart disease, or diabetes; these patients might be referred to a hospital or outpatient surgical center, where their specific medical conditions may be managed better. The ASA manual, assembled by the ASA Committee on Ambulatory Surgical Care and the ASA Task Force on Office-Based Anesthesia, titled Office-Based Anesthesia: Considerations for Anesthesiologists in Setting Up and Maintaining a Safe Office Anesthesia Environment (2), suggests several factors that should be taken into consideration when deciding whether the patient would be a good candidate for an office-based anesthetic (see Box 7.2). For any anesthesia provider, it is also important to be able to provide to his or her patient a clear explanation of what a particular anesthetic technique entails.

Box 7.2

Abnormalities of major organ systems and stability and optimization of any medical illness
Difficult airway
Previous adverse experience with anesthesia and surgery (such as malignant hyperthermia)
Current medications and drug allergies
Time and nature of the last oral intake (NPO status and ASA preprocedural fasting guidelines)
History of alcohol or substance use or abuse
Presence of an adult who assumes responsibility specifically for caring for and accompanying the patient from the office

MONITORED ANESTHESIA CARE: WHAT DOES THIS REALLY MEAN?

The ASA originally issued its position on MAC in 1986, and it was last amended in 2005. The statement has undergone several revisions over the years (3). The current statement defines MAC as follows:

Monitored anesthesia care is a specific anesthesia service for a diagnostic or therapeutic procedure. Indications for monitored anesthesia care include the nature of the procedure, the patient’s clinical condition and / or the potential need to convert to a general or regional anesthetic. Monitored anesthesia care includes all aspects of anesthesia care—a preprocedure visit, intraprocedure care and postprocedure anesthesia management.

During MAC, the anesthesiologist provides or medically directs a number of specific services, including, but not limited to, diagnosis and treatment of clinical problems that occur during the procedure; support of vital functions; administration of sedatives, analgesics, hypnotics, anesthetic agents, or other medications as necessary for patient safety; psychological support and physical comfort; and provision of other medical services as needed to complete the procedure safely. “Monitored anesthesia care may include varying levels of sedation, analgesia, and anxiolysis as necessary.” Only qualified personal should administer monitored anesthesia, because “the provider of monitored anesthesia care must be prepared and qualified to convert to general anesthesia when necessary.” In an effort to distinguish monitored anesthesia from general anesthesia, in 2003 the ASA added to the statement the following definition:

If the patient loses consciousness and the ability to respond purposefully, the anesthesia care is a general anesthetic, irrespective of whether airway instrumentation is required.

A patient might ask the anesthesia provider to help him or her understand the concept of different levels of sedation, and how they differ from general anesthesia. In 2004, the ASA House of Delegates amended its guidelines on the Continuum of Depth of Sedation, Definition of General Anesthesia, and Levels of Sedation / Analgesia (4). According to this document, different levels of sedation are determined based on the patient’s responsiveness, the status of the patient’s airway, whether the patient is breathing spontaneously or not, and the patient’s cardiovascular function (see Table 5.1). Definitions of the depth of sedation were provided and can be found in Chapter 5.

Is there a difference between MAC and conscious sedation? Because there is a variety of individuals who administer sedative medications, the ASA House of Delegates in 2004 issued a statement distinguishing MAC from moderate sedation (what the public recognizes as “conscious sedation”) (5). This is based on the different levels of sedation as noted in Table 5.1.

Following is an excerpt from Distinguishing Monitored Anesthesia Care From Moderate Sedation / Analgesia (Conscious Sedation):

Moderate Sedation / Analgesia (Conscious Sedation; hereinafter known as Moderate Sedation) is a physician service recognized in the CPT procedural coding system. During Moderate Sedation, a physician supervises or personally administers sedative and / or analgesic medications that can allay patient anxiety and control pain during a diagnostic or therapeutic procedure. Such drug-induced depression of a patient’s level of consciousness to a “moderate” level of sedation, as defined in JCAHO standards, is intended to facilitate the successful performance of the diagnostic or therapeutic procedure while providing patient comfort and cooperation. Physicians providing moderate sedation must be qualified to recognize “deep” sedation, manage its consequences and adjust the level of sedation to a “moderate” or lesser level. The continual assessment of the effects of sedative or analgesic medications on the level of consciousness and on cardiac and respiratory function is an integral element of this service.

Furthermore, the ASA has defined MAC in its Position on Monitored Anesthesia Care, last amended in 2005 (3). This physician service can be distinguished from moderate sedation in several ways (see Box 7.3).

Box 7.3

An essential component of MAC is the anesthesia assessment and management of a patient’s actual or anticipated physiologic derangements or medical problems that may occur during a diagnostic or therapeutic procedure. While MAC may include the administration of sedatives and/or analgesics often used for moderate sedation, the provider of MAC must be prepared for and qualified to convert to general anesthesia when necessary. Additionally, a provider’s ability to intervene to rescue a patient’s airway from any sedation-induced compromise is a prerequisite for the qualifications to provide MAC. By contrast, moderate sedation is not expected to induce depths of sedation that would impair the patient’s own ability to maintain the integrity of his or her airway. These components of MAC are unique aspects of an anesthesia service that are not part of moderate sedation.

The administration of sedatives, hypnotics, analgesics, as well as anesthetic drugs commonly used for the induction and maintenance of general anesthesia is often, but not always, a part of MAC. In some patients who may require only minimal sedation, MAC is often indicated because even small doses of these medications could precipitate adverse physiologic responses that would necessitate acute clinical interventions and resuscitation. If a patient’s condition and/or a procedural requirement is likely to require sedation to a “deep” level or even to a transient period of general anesthesia, only a practitioner privileged to provide anesthesia services should be allowed to manage the sedation. Due to the strong likelihood that “deep” sedation may, with or without intention, transition to general anesthesia, the skills of an anesthesia provider are necessary to manage the effects of general anesthesia on the patient as well as to return the patient quickly to a state of “deep” or lesser sedation.

Like all anesthesia services, MAC includes an array of postprocedure responsibilities beyond the expectations of practitioners providing moderate sedation, including assuring a return to full consciousness, relief of pain, management of adverse physiologic responses or side effects from medications administered during the procedure, as well as the diagnosis and treatment of coexisting medical problems.

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