Intravenous (IV) anesthetics may be used for induction of general anesthesia, maintenance of general anesthesia, and sedation. Sedation typically involves an agent called a “sedative-hypnotic” and refers to a state of calm and relaxation, whereas hypnosis refers to sleep. A sedative is often combined with an analgesic, which is used to treat pain. The combination of the two agents can be very effective; however, it may also potentiate each medication more than if they were given independently. Sedation involves a continuum from minimal sedation leading to moderate and deep sedation and eventually to general anesthesia. The definition of these states of consciousness has been published by the American Society of Anesthesiologists (ASA). In addition, the ASA has published practice guidelines for those who may administer sedation and standard monitoring required during a sedation case. The term monitored anesthesia care (MAC) does not refer to the depth of anesthesia but rather a sedation or service that is provided by an anesthesiologist. The term is falling out of favor and is being replaced by the term depth of sedation, regardless of who provides the service. Sedation is useful in a variety of settings: the intensive care unit (ICU) sedation for mechanical ventilation, sedation for procedures or imaging, and as an adjunct to regional anesthesia in the operating room (OR).

Minimal Sedation (Anxiolysis): Cognitive function may be impaired, but there is a normal response to verbal stimuli with unaffected airway, ventilation, or cardiovascular function.

Moderate Sedation/Anesthesia (aka Conscious Sedation): Purposeful response to verbal or tactile stimuli with airway, ventilation, and cardiovascular functions that are adequate and should require no intervention.

Deep Sedation/Analgesia: Purposeful response only following repeated or painful stimulation where the airway and ventilation often need support and the cardiovascular function is usually maintained. Providers who perform deep sedation should be qualified to respond to a patient who enters a state of general anesthesia.

General Anesthesia: Unresponsive even to painful stimuli where the airway and ventilation are generally inadequate without intervention and the cardiac function may need intervention (Table 17.1).

A task force of the ASA on sedation guidelines recommends that the clinician performing the sedation performs an assessment of the patient prior to administration of sedation. This should include the patient’s medical history, vital signs, allergies, current medications, response to previous sedation, and history of substance abuse. Additionally, a focused physical examination including heart and lung auscultation and airway evaluation should be included.

An explanation of the risks, benefits, and alternatives of the level of sedation required should be provided to patients or their legal guardian prior to the procedure. Patients undergoing sedation should be advised not to eat solids or drink liquids according to the ASA guidelines for perioperative fasting. In emergency situations, the risks and benefits of sedation on nonfasted individuals should be considered and discussed with the patient or guardian regarding the potential for pulmonary aspiration of gastric contents (Table 17.2).

Monitoring is recommended by the ASA according to the level of sedation. Data should be recorded prior to the start of sedation, during the procedure, and after completion (Table 17.3).

The personnel performing the sedation should not be the person performing the procedure and should be present to administer medications and monitor the patient during the procedure. This person may help with minor tasks related to the procedure when the patient is stable; however, he or she may not perform these tasks during a deep sedation. Additionally, he or she should be knowledgeable of the pharmacology of both sedating and analgesic medications as well as the reversal agents for those medications. There should be a basic life support (BLS) certified health care provider in the room, with advanced cardiac life support (ACLS) personnel available within 5 minutes. The exception is the administration of deep sedation, which requires the presence of an ACLS certified provider in the room.

Many sedation scales exist to help categorize the level of arousal during a procedure or within the ICU. They attempt to standardize the level of consciousness to facilitate communication between providers. Two of the more common scales are the Ramsay Scale, which was introduced over 30 years ago, and the Riker Sedation-Agitation Scale (SAS) (Tables 17.4 and 17.5).

Because sedation is a continuum and medications are used that can cause respiratory depression and hemodynamic compromise, rescue equipment should be readily available (Table 17.6).