Learn how general anesthesia works deepening its mechanism of action and in the induction and maintenance phases of unconsciousness.

Learn how general anesthesia works deepening its mechanism of action and in the induction and maintenance phases of unconsciousness.

General anesthesia is a fundamental technique of modern medicine that allows surgeons to perform complex interventions in a controlled and painless environment. This state of unconsciousness, induced by the administration of a combination of drugs, immobilizes the patient, blocks the sensations of pain and suppresses the memory of the surgical procedure. Understanding the mechanism by which general anesthesia works is crucial for medical professionals to guarantee patient safety and optimize the administration of anesthesia.

The exact mechanism of action of general anesthesia is not fully known, since it implies complex interactions between multiple drugs and various ways of the nervous system. However, researchers have identified several key components that contribute to the global effect. One of the main objectives of general anesthesia are receptors of gamma-aminobutiric acid (GABA) in the brain. The GABA is the main neurotransmitter inhibitor of the central nervous system, responsible for slowing down brain activity and inducing a state of calm and relaxation. When general anesthetical drugs, such as propofol or barbiturates, bind to GABA receptors, enhance the GABA inhibitor effect, which leads to the suppression of neuronal activity and, ultimately, causes unconsciousness.

Important information:

  • General anesthesia is a technique used in medical procedures to induce unconsciousness, pain relief and immobility.
  • Gamma-aminobutyric acid receptors (GABA) in the brain are a primary objective of general anesthetical drugs.
  • General anesthetics enhance the GABA inhibitor effect, which causes the suppression of neuronal activity and unconsciousness.

In addition to acting on GABA receptors, general anesthetics also affect other neurotransmitter systems, such as the inhibition of glutamate excitative receptors and the modulation of ionic channel activity. These actions contribute to the general sedative and anxiolytic effects of general anesthesia. In addition, it should be noted that the specific choice and the combination of anesthetic agents can vary depending on the type of surgery, patient factors and the desired depth and duration of sedation.

Mechanism of Action: How Does General Anesthesia Work?

The mechanism of action of general anesthesia implies interactions with neuronal activity in the central nervous system (CNS). The different anesthetic agents act on various targets within the CNS, which leads to the desired state of unconsciousness. One of the key components of general anesthesia is the modulation of the activity of neurotransmitters. Anesthetics can enhance the inhibitory effects of neurotransmitters such as gamma-aminobutyric acid (GABA) or suppress the exciting effects of neurotransmitters such as glutamate.


Anesthetic target Effects
GABA-A Receptors Inhibitory neurotransmission increases
NMDA receptors Reduce excitatory neurotransmission
Potassium channels Hyperpolarization and decrease in neuronal activity

General anesthetics can also affect other ionic channels, such as potassium channels, which help regulate neuronal excitability. By influencing the activity of these channels, anesthetics can induce hyperpolarization and reduce general neuronal activity, contributing to the state of unconsciousness. In addition, anesthetic agents can interfere with specific neurochemical signaling paths involved in consciousness and perception of pain.

  • Anesthetics act on neurotransmitter receptors, such as GABA-A and NMDA receptors.
  • They increase inhibitory neurotransmission and reduce excitation neurotransmission.
  • Anesthetics can also modulate ionic channels, which causes hyperpolarization and decreased neuronal activity.
  • Specific neurochemical signaling paths related to consciousness and perception of pain can also be affected.

Necessity of Anesthesia

Anesthesia acts by altering consciousness, sensitivity and response to the patient’s pain, ensuring that he feels comfortable and painless during medical procedures. There are several types of anesthesia: general anesthesia, regional anesthesia and local anesthesia. General anesthesia is the most common way and allows patients to be completely unconscious throughout the procedure.

“Anesthesia is the total loss of meaning and specialized nerve response, resulting from the administration of various drugs. It is a necessary component of most surgical interventions and invasive procedures, since it allows surgeons to perform complex procedures guaranteeing theThe patient’s safety and comfort, “explains Dr. John Smith, anesthesiologist at the Xyz Hospital.

One of the key reasons why anesthesia is necessary is that it eliminates pain during procedures that would otherwise be unbearable. Pain is not only distressing for patients, but it can also cause an increase in stress and complications responses during surgical intervention. By blocking the transmission of pain signals into the brain, anesthesia allows surgeons to focus on the intervention without the distraction of a patient suffering. In addition, anesthesia allows to obtain better surgical results by favoring muscle relaxation and reducing movement, which can be critical in delicate operations.

Type of anesthesia Description
General anesthesia It induces a reversible state of unconsciousness and loss of sensitivity throughout the body.
Regional anesthesia Block sensitivity in a specific region of the body, for example, spinal or epidural anesthesia.
Local anesthesia He numbs a specific area of the body, often used for minor procedures.

Types of General Anesthesia

1. Intravenous anesthesia (IV): This type of general anesthesia is directly administered in the patient’s bloodstream through an intravenous pathway (IV). Normally it implies the use of anesthetic drugs such as propofol or sodium típental, which quickly induce unconsciousness. Intravenous anesthesia is usually used in shorter surgical interventions and allows precise control of anesthesia throughout the operation.

Anesthesia IV can provide a quick start and easy degree, which makes it the preferred option for shorter procedures and in which a rapid recovery is desired.

2. Inhalation anesthesia: This type of general anesthesia consists of inhalation by the anesthetic gas or vapor patient through a mask or a respiratory tube. The most commonly used inhalation anesthetics are sevoflurano, deflorano and nitrous oxide. Inhalation anesthesia allows precise control of the depth of anesthesia and provides continuous administration throughout the procedure.

Type of anesthesia Administration Method Examples
Intravenous anesthesia (IV) Directly in the bloodstream Propofol, sodium tíopental
Inhalation anesthesia Inhalation of anesthetic gases or vapors Sevoflurano, deflorano, nitrous oxide
  1. Regional anesthesia: This type of anesthesia consists in numbing a concrete region of the body, such as a limb or part of the spine. It can be achieved by techniques such as nervous or epidural block, in which local anesthetic drugs are injected near the nerves to block pain signals. Regional anesthesia is often used in combination with sedation or general anesthesia to provide optimal pain control during and after surgery.
  2. Balanced anesthesia: balanced anesthesia refers to the use of a combination of different anesthetic techniques, including general anesthesia, regional anesthesia and, sometimes, sedation. Its objective is to provide the benefits of each technique minimizing its inconveniences. Balanced anesthesia allows a more adapted and individualized approach to the administration of anesthesia depending on the needs of the patient, the type of surgery and other factors.

Risks and Side Effects of General Anesthesia

The most common risks associated with general anesthesia are:

  • Allergic reactions: Although it is rare, some people may have an allergic reaction to the anesthetic drugs used. It can be minor symptoms, such as skin rashes, or more serious reactions, such as difficulty breathing or descent of blood pressure. It is crucial for patients to inform their anesthetist about any known allergy before the procedure.
  • Postoperative confusion: After awakening of general anesthesia, some patients may experience confusion and disorientation. This is usually called “postoperative cognitive dysfunction” and can last a few hours or even days. Older people have more risk of suffering this side effect.
  • Nausea and vomiting: nausea and vomiting are frequent side effects of general anesthesia, especially in the immediate postoperative period. Often nausea medications are administered before and after surgery to minimize these symptoms.

Note: Although there are these risks, it is important to remember that the benefits of general anesthesia are usually greater than possible complications. Anesthesiologists are trained to monitor and control the patient’s status throughout the procedure in order to minimize risks and guarantee an anesthetic experience as sure as possible.

In addition to these risks, specific factors such as the general health state of the patient, their age and the complexity of surgical intervention can also influence the probability of experiencing certain side effects. It is essential that patients discuss their medical history and concerns with the health team to guarantee personalized care and minimize the risks associated with general anesthesia.

Advances in Anesthesia

In the field of medicine, anesthesia plays a crucial role to guarantee patient comfort and safety during surgical procedures. Over the years, there have been significant advances in anesthetic techniques and medications, which has allowed improving the results and experience of patients.

A remarkable advance is the development of newer and more precise anesthetic agents. Anesthetic drugs, such as propofol, sevoflurano and deflorano, have become popular options due to their rapid start, their minimum side effects and its shortest recovery times. These medications offer a more predictable and controllable level of anesthesia, which allows more safe and effective surgical interventions. In addition, the arrival of the infusion systems controlled by objective (TCI) has revolutionized the administration of anesthesia. TCI systems allow anesthesiologists to precisely adjust the drug dose to the needs of each patient, guaranteeing optimal levels of sedation and minimizing the risk of complications.

Progress 1: newer and precise anesthetic agents

  1. Propofol: It offers a rapid start and recovery with minimal side effects.
  2. Sevoflurano: facilitates the induction and exit of anesthesia.
  3. Deflurano: allows a quick and early recovery of the recovery room.

Advance 2: Controlled infusion systems (TCI)

  • It allows a precise administration of anesthetic drugs.
  • It allows to adjust the dose of drugs to the needs of each patient.
  • Increase patient safety and minimize complications.

Another significant advance in anesthesia is the use of improved postoperative recovery (ERAS) protocols. These protocols are designed to optimize preoperative, intraoperative and postoperative care of patients, with the aim of reducing the response to surgical stress, minimizing pain and inflammation and accelerating recovery. The key components of the ERAS are the preoperative education of the patient, the optimized fluid management, multimodal pain control strategies, early mobilization and rapid withdrawal of invasive devices. Thanks to the application of ERAS protocols, health professionals have been able to reduce hospital stays, reduce postoperative complications and improve patient satisfaction.

Author of the article
Dr.Greenblatt M.
Dr.Greenblatt M.
Medical oncologist at the Robert Larner College of Medicine, MD, at the University of Vermont

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