Procedural sedation (PS), previously incorrectly referred to as 'conscious sedation,' refers to techniques, medications, and maneuvers performed to help a patient tolerate unpleasant or painful procedures, avoiding potential unwanted memories associated with such procedures. Because the proper use of PS also aims to decrease the patient's perception of pain and is generally obtained through the administration of analgesics combined to a sedative, PS can also serve as procedural sedation analgesia (PSA). Furthermore, PS also increases the likelihood of a successful procedure while decreasing the time required to perform it. Additionally, PS increases safety for the patient and personnel attending the patient. These approaches include medications, psychological techniques, and/or physical maneuvers to achieve the indented effect. According to the American College of Emergency Physicians (ACEP), PS is a 'technique of administering sedatives or dissociative agents with or without analgesics to induce a state that allows the patient to tolerate unpleasant procedures while maintaining cardiorespiratory function. PSA is intended to result in a depressed level of consciousness that allows the patient to maintain oxygenation and airway control independently.'

In various settings, the practice of PS (and PSA) has considerable variability, is practiced with varying degrees of skill, and has been the subject of controversy in the not-so-distant past. The practice of PSA, in fact, is not the exclusive preserve of anesthesia practitioners but is now routinely adopted by other specialists, such as emergency clinicians, critical care specialists, and several nurse specialists. On these bases, this chapter is intended to set out a standard method of practice and address some of the controversies along with providing additional outside resources for the learner’s enrichment. The recommendations herein are not intended to be adopted en bloc but must be customized to the setting where they are used. The matter has been by several scientific societies. In 2018, the American Society of Anesthesiologists (ASA) in conjunction with the American Association of Oral and Maxillofacial Surgeons (AAOMS), the American College of Radiology (ACR), the American Dental Association (ADA), the American Society of Dentist Anesthesiologists (ASDA), and the Society of Interventional Radiology (SIR) organized the task force on Moderate Procedural Sedation and Analgesia, releasing updated practice guidelines. Furthermore, The American Society for Gastrointestinal Endoscopy (ASGE) published guidelines on the use of PSA for gastrointestinal endoscopic procedures. However, there are differences between the proposed guidelines. For example, in contrast to the ASA recommendations, ASGE guidelines do not consider the capnography monitoring useful during PS.

It is essential to understand that sedation, dissociation, and analgesia are separate concepts. Sedation is enabling the patient to lie very still; analgesia is pain relief by central or peripheral interventions, while dissociation is the production of a state of mind-body separation. As a consequence, PS is not general anesthesia or pain control alone, but it is explainable as a tailored approach to the patient, based on anxiety level and pain aimed at achieving optimal sedation and analgesia for performing noninvasive and minimally invasive procedures, conducted primarily in contexts outside of the operating theater such as emergency, dentistry, radiology, and gastrointestinal endoscopy.

Different evaluation methods have been developed for the degree of sedation, both in the operating theater and in environments outside the theater. The Ramsay scale indicates a straightforward approach described by Ramsey and colleagues in 1974. The tool indicates six categories from patient awake but anxious, agitated, or restless, to patient awake but cooperative, orientated, and tranquil, to patient drowsy but responsive to commands, patient asleep (brisk response to glabella tap or loud auditory stimulus), patient asleep with sluggish response to a stimulus, and finally patients with no response to noxious stimuli. Although this approach continues to be the most widely used scale for the assessment and monitoring of sedation, one major limitation is the non-precise distinction between intentional responses and unintentional ones. Recently, the Ramsey scale has undergone modifications to match the AAP and JCAHO guidelines better. After scoring eight characteristics, a score indicates anxiolysis (2 to 3), moderate sedation (4 to 5), deep sedation (6), and general anesthesia (7 to 8). Another widely used instrument is the Observer's Assessment of Alertness/Sedation (OAA/S) scale. It scores five categories: no response to shaking; response to mild prodding; response to name called loudly; lethargic response to name; and readily responds to name. This tool is an easy-to-use instrument, although it does not well discriminate among deep levels of sedation.

Practically, the most commonly accepted terms for sedation depth are:

1. Minimal: also called anxiolysis; the patient remains awake but relaxed, able to interact.

2. Moderate: also called conscious sedation, the patient has depressed consciousness but will respond to verbal requests or react to touch. Breathing remains intact, and no support is needed.

3. Deep: The patient cannot be easily aroused but will respond to repeated or painful stimuli. Breathing may be impaired and may need to be supported.

4. Dissociative: a trance-like state wherein the patient remains awake but unaware of the pain and retains no memory of the event. They can follow commands, and airway reflexes remain intact.

It is generally accepted that, due to patients' varying sensitivities to medications as well as pre-existing co-morbidities, patients may slip into a deeper level than anticipated; the operator must prepare for this event.