The 6 types of anesthesia (with their effects and characteristics).

These are the main types of anesthesia used in medicine to prevent pain.

Anesthesia is a fundamental technique for any surgical intervention. The world of modern medicine, and especially surgery, would be unthinkable if the different types of anesthesia used today did not exist, both for mild interventions such as a dental filling and for more complex ones, such as a gastric by-pass.

Anesthesiologists use different methods to make the patient feel no pain while undergoing an operation. Let's see what the main types of anesthesia are and what they are used for..

The main types of anesthesia (classified)

Many people, when they hear the word anesthesia, the first thing they think of is a numbing substance, capable of making the person to whom it has been administered lose consciousness. This idea is partly true, but it should be said that anesthesia refers to the set of techniques and technologies used to prevent pain in patients both during open-heart surgery and to reduce the discomfort they may have in their daily lives, such as stinging eyes or sore throat.

Anesthetic substances can be administered by injection, inhalation, topical lotion, aerosols, skin patches or eye drops, and their main purpose is to induce anesthesia.Their main purpose is to cause a loss of sensibility, either in a specific area or in the whole organism.

In the latter case, the patient usually not only does not feel pain in any part of his body, but also loses consciousness.

The type of anesthesia to be used will depend on different factors, among which we highlight:

• Type of surgical intervention
• Area to be operated on
• Duration of the operation
• Current and previous clinical picture
• Possible allergies of the patient
• Reactions prior to anesthesia (both patient's and family members')
• Medications the patient is taking
• Age, height and weight

Let's see what are the main types of anesthesia.

1. Local anesthesia

Local anesthesia is a type of medication that only acts on a small part of the body, where an anesthetic drug is applied to prevent pain.. It can be topical anesthesia if the drug is applied in drops (eyes), spray (throat) or paste (skin), or infiltration if it is injected with a syringe and needle into the area to be operated on.

The duration of the effects of the local anesthetic will depend on several factors, including:

• Type of anesthetic (p. e.g., bupivacaine, lidocaine...).
• Total dose: the higher the dose, the earlier it acts and the longer its effect lasts.
• If adrenaline is added (vasoconstrictor that takes longer to eliminate the drug).

As a general rule, the effects of a local anaesthetic usually last between half an hour and two hours..

2. Regional anesthesia

Regional anesthesia affects a larger area compared to local anesthesia.. In this case, it involves applying an anesthetic drug that makes a specific region, such as an arm, a leg or the lower half of the body, numb.

Different techniques can be used depending on the area to be treated:

Truncal and plexus anesthesia 2.1.

If the intervention is on any part of an upper limb, such as a shoulder, hand or elbow, or a lower limb, such as a hip, foot or knee, there are two options: truncal and plexus, there are two options: truncular and plexus..

The difference between truncal anesthesia and plexus anesthesia is that in the former the anesthetic is injected on one nerve, while in the latter the anesthetic is injected in several nerves involved.

2.2. Spinal and epidural anesthesia

Another regional anesthesia technique used by anesthesiologists consists of puncturing the back and injecting the anesthetic into several nerves involved. consists of puncturing the back and injecting the anesthetic in the area near the spinal column, where the nerves enter the spinal cord.where the nerves enter the spinal cord to send pain sensations to the brain.

Using this technique the transmission of these sensations is blocked and the person does not have the sensation of pain. Within this modality there are two variants.

Using spinal or intrathecal anesthesia, the needle goes through the dura mater, which is the protective covering of the spinal cord, and the anesthetic is injected into the spinal cord.and the anesthetic is injected into the space through which the cerebrospinal fluid (CSF) circulates. This substance bathes and protects the spinal cord and in case of finding dissolved substances in them, such as anesthesia, it carries them to the central nervous system.

On the other hand, in the epidural anesthesia technique, the needle does not pass through the dura mater.. In this case, the anesthetic substance remains in the entrance zone of the nerves of the medulla, on the outside of the dura. A catheter is usually introduced to allow continuous administration of the anesthetic, this technique being used in childbirth and in postoperative pain control.

In all regional anesthesia techniques, also known as locoregional anesthetic modalities, the patient is awake while undergoing the procedure. while undergoing the procedure. However, he/she does not feel pain during the process since he/she is under the effects of the anesthesia, which will have been injected in one or another region of his/her body that is to be surgically treated.

3. General anesthesia

When general anesthesia is applied, the person who has been injected will temporarily have will have total absence of sensibility in all his body temporarily, accompanied also by loss of consciousness.. This type of procedure is applied in complex interventions, in which it will be necessary to cut the patient open or to operate in several parts simultaneously.

As general anesthesia implies that the patient is induced to sleep, there are many patients who have to undergo surgery who are afraid of this procedure. Generally, anesthesia is safe, but it does involve certain risks, especially in the case of general anesthesia. Among the problems associated with this type of technique we have:

• Arrhythmia
• Respiratory problems
• Allergic reaction to anesthesia

A striking symptom is that of delirium after general anesthesia.. This is a condition in which the patient is confused and unaware of what is going on around him/her.

This type of delirium occurs especially in patients over 60 years of age who have just undergone surgery and show confusional signs for several days after the operation. It can also occur in children when they first wake up from anesthesia.

Another problem related to anesthesia is the very thing anesthesia is intended to prevent: being conscious during the process.. Some people may hear sounds while undergoing surgery and others, unfortunately, may feel pain during the procedure. While these are rare situations, they are not at all pleasant to experience.

Whatever the case may be, knowing what we are facing before undergoing surgery will help us to be more at ease, and that is why the different phases of general anesthesia are mentioned below.

3.1. Induction

In the induction phase, the anesthesiologist administers the anesthetic drug to achieve hypnosis, analgesia, amnesia and relaxation..

As we have already mentioned, in general anesthesia, consciousness is totally lost, a phenomenon called hypnosis, which could be defined as being in a kind of pharmacologically induced coma. However, hypnosis does not mean that no pain is felt, which is why it is also necessary to administer some type of analgesic, normally derived from morphine.

Relaxation is induced by means of Muscle relaxants.These are usually applied when the surgery requires the patient's muscles to be relaxed or a tube has to be placed into the trachea to ensure that the patient can continue to breathe during the operation.

Throughout this phase, the anesthesia team monitors the patient's vital signs to make sure that everything is going well.. Basically, it consists of checking that the patient is still alive and is not having any crises, evaluating oxygenation, ventilation and body temperature, among other parameters. To do this, sensors are placed on the patient's body and connected to monitors that analyze their physiological signals.

3.2. Maintenance

Once the induction phase is over comes the maintenance phase. In this phase the necessary drugs continue to be administered so that the operation can be carried out safely..

This administration of anesthetic drugs can be done by venous route, which is called T.I.V.A. (total intravenous anesthesia), or also by inhaled route in which the drugs are applied by means of the apparatus with which the patient is being ventilated. The combination of both anesthetic techniques is called balanced anesthesia.

3.3. Awakening

Once the operation has been completed, the anesthesiological team wakes the patient up.. To achieve this, the inhalation drug supply is first cut off and, if necessary, anesthetic antagonists are administered, substances which therefore awaken the patient instead of numbing him or her.

Once the patient has regained an adequate level of consciousness, the devices used to control ventilation are removed and the patient is transferred to the Resuscitation Unit, where his or her vital signs will continue to be monitored until full consciousness and function have been recovered.