General anesthesia works by deeply sedating a person, so that the body’s consciousness, sensitivity and reflexes are lost, so that surgeries can be performed without feeling pain or discomfort during the procedure.
It can be injected through the vein, having an immediate effect, or inhaled through a mask, reaching the bloodstream after passing through the lungs. The duration of its effect is determined by the anesthetist, who decides on the type, dose and quantity of the anesthetic medication.
However, general anesthesia is not always the first choice for surgeries, being reserved for those larger and more time-consuming surgeries, such as abdominal, thoracic or cardiac surgeries. In other cases, anesthesia of only part of the body, such as local, may be indicated in cases of dermatological surgery or removal of teeth, or epidural anesthesia, for deliveries or gynecological surgeries, for example. Learn about the main types of anesthesia and when to use it .
Main types of general anesthesia
General anesthesia can be performed through the vein or by inhalation, and there is no better type than the other, and the choice will depend on the strength of the medication for the type of surgery, preference of the anesthetist or availability in the hospital.
There are several types of drugs used, which are usually combined to, in addition to rendering the person unconscious, causing insensitivity to pain, muscle relaxation and amnesia, so that everything that happens during surgery is forgotten by the person.
1. Inhalation anesthesia
This anesthesia is done by inhaling gases that contain anesthetic medications, so it takes a few minutes to take effect, because the medication must first pass through the lungs until it reaches the bloodstream and then the brain.
The concentration and quantity of the inhaled gas are determined by the anesthetist, depending on the time of the surgery, which can be from a few minutes to several hours, and the sensitivity of each person to the medication.
To cut the effect of anesthesia, the release of gases must be interrupted, since the body naturally eliminates anesthetics, which are in the lungs and bloodstream, through the liver or kidneys.
- Examples : some examples of inhaled anesthetics are Tiomethoxyflurane, Enflurane, Halothane, Diethyl ether, Isoflurane or Nitrous oxide.
2. Anesthesia through the vein
This type of anesthesia is done by injecting the anesthetic medication directly into the vein, causing an almost immediate sedation. The depth of sedation depends on the type and amount of medication injected by the anesthetist, which will also depend on the duration of the surgery, the sensitivity of each person, in addition to age, weight, height and health conditions.
- Examples : examples of injectable anesthetics include Thiopental, Propofol, Etomidate or Ketamine. In addition, the effects of other drugs can be used to enhance anesthesia, such as sedatives, opioid analgesics or muscle blockers, for example.
How long the anesthesia lasts
The duration of anesthesia is programmed by the anesthetist, depending on the time and type of surgery, and the choice of medication used for sedation.
The time it takes to wake up takes from a few minutes to a few hours after the end of the surgery, different from the ones used in the past, which lasted all day, since, nowadays, medicines are more modern and efficient. For example, the anesthesia performed by the dentist has a very low dose and lasts a few minutes, while the anesthesia required for heart surgery can last for 10 hours.
In order to perform any type of anesthesia, it is important that the patient is monitored, with devices to measure heart rate, blood pressure and breathing, since, as the sedation can be very deep, it is important to control the functioning of vital signs .
Some people may experience side effects during anesthesia or even a few hours later, such as feeling sick, vomiting, headache and allergies to the active ingredient of the medication.
The most serious complications, such as breathlessness, cardiac arrest or neurological sequelae, are rare, but they can occur in people with very poor health, due to malnutrition, heart, lung or kidney diseases, and who use many medications or illicit drugs, for example. example.
It is even more rare for anesthesia to have a partial effect, such as withdrawing consciousness, but allowing the person to move, or even the other way around, when the person is unable to move, but can feel the events around them.