General anesthetics bring about a reversible loss of consciousness and loss of pain in order for surgeons to operate on a patient. The use of general anesthetics is common, but how they produce their effects is still not fully understood. Show General anesthesia is a medicine that is administered intravenously (IV) or through a tube or mask. It is performed by an anesthesiologist or nurse anesthetist, a specially trained doctor or nurse who will also monitor a patient’s vital signs and rate of breathing during the procedure. Under general anesthesia, people are unable to feel pain (analgesic) and will be unconscious. It is more commonly used for major operations and during surgery. A person may also experience amnesia temporarily following the anesthetic. General anesthetics have been widely used in surgery since 1842 when Crawford Long administered diethyl ether to a patient and performed the first painless operation. In this article, we will cover a number of topics, including the differences between general anesthesia and sedation, potential side effects of general anesthesia, associated risks, and some theories regarding how they work. There are a number of potential side effects of general anesthesia. Some individuals may experience no side effects, whereas others may experience a few. None of the side effects are particularly long lasting, and they tend to occur right after the anesthesia. Side effects of general anesthesia can include:
Overall, general anesthesia is very safe. Even particularly ill patients can be safely anesthetized. The surgical procedure itself offers the most risk. However, older adults and those undergoing lengthy procedures are most at risk of negative outcomes. These outcomes can include:
Some specific conditions increase the risk to the patient undergoing general anesthetic, such as:
Death as a result of general anesthetic does occur, but only very rarely — roughly 1 in every 100,000. Unintended intraoperative awarenessThis refers to rare cases in which patients report a state of awareness during an operation, after the point at which the anesthetic should have removed all sensation. Some patients are conscious of the procedure itself, and some can even feel pain. Unintended intraoperative awareness is incredibly rare, affecting an estimated 1 in every 19,000 patients undergoing general anesthesia. Because of the muscle relaxants given alongside anesthesia, patients are unable to signal to their surgeon or anesthetist that they are still aware of what is happening. Patients who experience unintended intraoperative awareness can suffer long-term psychological problems. Most often, the awareness is short-lived, and a person is only aware of vague sensory experiences such as sounds, touches, or movements. As unintended intraoperative awareness is so infrequent, it is not clear exactly why it occurs. The following are considered to be potential risk factors:
Medical teams may administer IV sedation for the following procedures:
General anesthesia is also used for more lifesaving procedures such as heart surgeries or treatments for cancer, although it does carry some risks. Sedation is administered through an IV. There are three types of sedation, including:
Sedation and general anesthesia are both forms of anesthesia, but people will experience different effects depending on the type administered by doctors during a procedure, including the level of consciousness, breathing support, and possible side effects. Sedation is generally characterized by people feeling drowsy but being in a relaxed state of consciousness. Whereas, when people are under general anesthesia, they have a complete loss of consciousness. Cardiovascular function is usually maintained throughout sedation, and people are able to breathe independently. However, this does not mean that respiratory assistance may not be used in some instances with sedation. On the other hand, general anesthesia usually impairs breathing, and monitoring and breathing assistance are required. The adverse effects that may be associated with general anesthesia are avoided with sedation, as the recovery period from sedation is typically quicker. Alongside general anesthetic, there are other types, including:
There are two main forms of regional anesthesia:
There are a number of reasons why general anesthesia may be chosen over local anesthesia. In some instances, the patient is asked to choose between general and local anesthetic. This choice depends on:
The main reasons for opting for general anesthetic are:
The purpose of general anesthetic is to induce:
However, using general anesthetic poses a higher risk of complications than local anesthesia. If the surgery is more minor, an individual may choose local anesthesia, especially if they have an underlying condition, such as sleep apnea. Presurgical evaluationBefore receiving general anesthesia, patients will have a presurgery assessment to determine the most appropriate drugs to use, the quantities of those drugs, and in which combination. Some factors to explore in a presurgical evaluation include:
It is essential that these questions are answered accurately. For instance, if a history of alcohol or drug use is not mentioned, an inadequate amount of anesthesia might be given, which could lead to dangerously high blood pressure or unintended intraoperative awareness. Guedel’s classification, designed by Arthur Ernest Guedel in 1937, describes the four stages of anesthesia. Modern anesthetics and updated delivery methods have improved the speed of onset, general safety, and recovery, but the four stages remain essentially the same: Stage 1, or induction: This phase occurs between the administration of the drug and the loss of consciousness. The patient moves from analgesia without amnesia to analgesia with amnesia Stage 2, or excitement stage: The period following a loss of consciousness, characterized by excited and delirious activity. Breathing and heart rate become erratic, and nausea, pupil dilation, and breath-holding might occur. Because of irregular breathing and the risk of vomiting, there is a danger of choking. Modern, fast-acting drugs aim to limit the time spent in stage 2 of anesthesia. Stage 3, or surgical anesthesia: Muscles relax, vomiting stops, and breathing is depressed. Eye movements slow and then cease. The patient is ready to be operated on. Stage 4, or overdose: Too much medication has been administered, leading to the brain stem or medullary suppression. This results in respiratory and cardiovascular collapse. The anesthetist’s priority is to take the patient to stage 3 of anesthesia as quickly as possible and keep them there for the duration of the surgery. The exact mechanisms that produce the state of general anesthesia are not well known. The general theory is that their action is induced by altering the activity of membrane proteins in the neuronal membrane, possibly by making certain proteins expand. Of all the drugs used in medicine, general anesthetics are an unusual case. Rather than a single molecule acting at a single site to produce a response, there is a huge variety of compounds, all of which generate quite similar but widespread effects, including analgesia, amnesia, and immobility. The chemical makeup of general anesthetic drugs ranges from the simplicity of alcohol’s chemical makeup to the complexity of sevoflurane. General anesthetics are known to act at a number of sites within the central nervous system. The importance of these sites on the induction of anesthesia is not fully understood. These sites include:
A number of different neurotransmitters and receptors are also known to be involved in general anesthesia:
Although general anesthetics hold many mysteries, they are hugely important in surgery and the field of medicine at large. General anesthesia can cause some potential side effects and complications. However, overall, it is a very safe medicine, and it is usually the surgery itself that carries the most risk. Before any type of anesthesia is administered, patients will have an assessment to determine the most appropriate combination of drugs to use and the quantities, depending on if a person has any risk factors or family history of allergies to an anesthetic. What are the 4 stages of general anesthesia?They divided the system into four stages:. Stage 1: Induction. The earliest stage lasts from when you first take the medication until you go to sleep. ... . Stage 2: Excitement or delirium. ... . Stage 3: Surgical anesthesia. ... . Stage 4: Overdose.. What is the order of stages of general Anaesthetics?∎ General anaesthesia can be divided into three stages: induction, maintenance and emergence.
What are the 3 phases of anaesthesia recovery?Phases of Postanesthesia Care
The postanesthesia period may be separated into three levels of care: Phase I, Phase II, and Extended Care. 5 Each phase of recovery may occur in one PACU or in multiple locations, which may include the patient's room (see Table 1).
What drug is used at the initial stage of anesthesia?Propofol, etomidate, and ketamine are the intravenous (IV) sedative-hypnotic agents commonly used to induce general anesthesia (table 1), while adjuvant agents (eg, opioids, lidocaine, midazolam, and volatile anesthetics) are often used to supplement the effects of the primary sedative-hypnotic induction agent (table 2 ...
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