Twilight anesthesia is an

anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into tw ...

technique where a mild dose of sedation is applied to induce

anxiolysis An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiet ...

(anxiety relief),

hypnosis Hypnosis is a human condition involving focused attention (the selective attention/selective inattention hypothesis, SASI), reduced peripheral awareness, and an enhanced capacity to respond to suggestion.In 2015, the American Psychologica ...

, and

anterograde amnesia In neurology, anterograde amnesia is the inability to create new memories after the event that caused amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. ...

(inability to form new memories). The patient is not unconscious, but sedated. During surgery or other medical procedures, the patient is under what is known as a "twilight state", where the patient is relaxed and "sleepy", able to follow simple directions by the doctor, and is responsive. Generally, twilight anesthesia causes the patient to forget the surgery and the time right after. It is used for a variety of surgical procedures and for various reasons. Just like regular

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), a ...

, twilight anesthesia is designed to help a patient feel more comfortable and to minimize pain associated with the procedure being performed and to allow the medical practitioner to practice without interruptions.

Overview

Twilight anesthesia is also known as twilight sleep and allows an easy awakening and a speedy recovery time for the patient.

Anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), a ...

is used to control pain by using medicines that reversibly block nerve conduction near the site of administration, therefore, generating a loss of sensation at the area administered. Close monitoring by the Anesthesia Provider will sometimes be provided, to help keep the patient comfortable during a medical procedure, along with other drugs to help relax the body. It can also help control breathing,

blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressur ...

blood flow Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuousl ...

, and

heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and e ...

and rhythm, when needed. There are four levels of sedation by anesthesia.

Level one

This level, called ''minimal sedation'', causes

, a drug-induced state in which the patient responds normally to verbal commands. Although the

cognition Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thoug ...

and coordination of the patient are impaired,

cardiovascular The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

and ventilatory functions remain unaffected.

Level two

This level, called ''moderate sedation/analgesia'' or ''conscious sedation'', causes a drug induced depression of consciousness during which the patient responds purposefully to verbal commands, either alone or accompanied with light physical stimulation. Breathing tubes are not required for this type of

. This is twilight anesthesia.

Level three

This level, called ''deep sedation/analgesia'', causes a drug-induced depression of consciousness during which the patient cannot be easily aroused, but responds purposefully following repeated or painful stimulation. Ventilatory functions may be impaired, so breathing tubes are required.

Cardiovascular The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

functions are usually sustained.

Level four

This level, called ''

general anesthesia General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...

'', causes a drug-induced depression of consciousness during which the patient cannot be aroused even by painful stimulation. Ventilatory function is often impaired and

functions may be impaired.

Applications

Several factors are taken into consideration when determining which level of

is used under which type of medical procedures. Along with the factors determined, different types of anesthesia medications are used depending on the medical procedure being done. While the patient is under conscious sedation by

, depending on the type and dose administered, they are in a state that is called by some, a “twilight” state.

Drugs and technology used

Some of the same drugs used in general anesthesia are also used for twilight anesthesia, except in smaller doses and in a bolus interval (a concentrated mass of a substance administered intravenously for diagnostic or therapeutic purposes). These drugs can be administered via gases, such as

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...

(laughing gas), or

intravenously Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...

, with drugs such as

ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...

(pediatrics primarily, and infrequently in adults),

propofol Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation ...

, and

midazolam Midazolam, sold under the brand name Versed among others, is a benzodiazepine medication used for anesthesia and procedural sedation, and to treat severe agitation. It works by inducing sleepiness, decreasing anxiety, and causing a loss of ...

. Twilight anesthesia alone is not used to provide relief from surgical pain; therefore, it is always given in conjunction with a local or regional anesthetic. Additionally, IV sedation is frequently administered as a concoction of several agents including those previously mentioned for induction and maintenance of anesthesia, as well as a

benzodiazepine Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...

(usually

, but

temazepam Temazepam (sold under the brand names Restoril among others) is a medication of the benzodiazepine class which is generally used to treat severe or debilitating insomnia. It is taken by mouth. Temazepam is rapidly absorbed, and significant hypn ...

flunitrazepam Flunitrazepam, also known as Rohypnol among other names, is a benzodiazepine used to treat severe insomnia and assist with anesthesia. As with other hypnotics, flunitrazepam has been advised to be prescribed only for short-term use or by those ...

are also used via the oral route) and a narcotic/systemic analgesic such as

demerol Pethidine, also known as meperidine and sold under the brand name Demerol among others, is a synthetic opioid analgesic, pain medication of the phenylpiperidine class. Synthesized in 1938 as a potential anticholinergic agent by the German chemis ...

fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocaine ...

. As discussed in the levels of sedation by anesthesia, assistance with breathing tubes ( ETT or LMA) are not generally used for this type of anesthesia.

Effects

A few studies have been geared towards studying the effects of post operative

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

regimes which measure the quality of recovery period and health-related quality of life. Factors other than degree of

analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals ...

and presence of analgesic agent-related side effects (e.g., fatigue, physical functioning, and mental health) may potentially influence these outcomes. Twilight anesthesia offers a limited recovery period after procedures, and is usually associated with less nausea and vomiting than

which makes it a popular choice among doctors who are performing procedures such as minor plastic surgeries.

Uses

Twilight anesthesia is applied to various types of medical procedures and surgeries. It is a popular choice among surgeons and doctors who are performing anything from minor plastic surgeries to dental work, and procedures that do not require extensive operations or long durations in favor of less nausea and a limited recovery period after surgery. Twilight anesthesia is used for surgical uses.

References

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