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

Anesthesia is a fundamental technique for all surgical intervention. The world of modern medicine, and especially that of surgery, would be unthinkable if there were no different types of anesthesia that are used today, both for mild interventions such as a dental filling and for more complex ones, such as a by-pass gastric.

Anesthesiologists use different methods to make the patient pain-free while undergoing an operation. Let's see what the main types of anesthesia are and what they are used for.

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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 causing the person to whom it has been administered to lose consciousness. This idea is partly true, but it can be said that anesthesia refers to the set of techniques and technologies used to prevent pain in the patient both during open heart surgery and to reduce the discomfort they may have in their day to day, such as itching in the eyes or bad de throat.

Anesthetic substances can be given by injection, inhalation, topical lotion, sprays, skin patches, or eye drops., and its main objective is to cause a loss of sensitivity, either in a specific area or throughout the body.

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

The type of anesthesia that will 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 in the patient and in 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 medicine that only acts on a small part of the body, applying an anesthetic drug over it to prevent pain. It can be topical anesthesia if the drug is applied in drops (eyes), spray (throat) or paste (skin), or infiltrations if injected with a syringe and needle in the area to be intervened.

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

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

As a rule, the effects of a local anesthetic 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 is a question of applying an anesthetic drug that makes a specific region, such as an arm, a leg or the lower half of the body, numb.

Depending on the area to be treated, different techniques can be used:

2.1. Truncal and plexus anesthesia

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

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

2.2. Spinal and epidural anesthesia

Another regional anesthesia technique used by anesthesiologists consists of puncturing the back and injecting the anesthetic in the area near the spine, where 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 we find two variants.

Using spinal or intrathecal anesthesia, the needle passes through the dura mater which is the protective covering of the spinal cord., and the anesthetic is injected into the space through which the cerebrospinal fluid (LCR). This substance bathes and protects the spinal cord and if dissolved substances are found in them, such as anesthesia, it takes them to the central nervous system.

Secondly, in the epidural anesthesia technique, the needle does not pass through the dura mater. In this case, the anesthetic substance remains in the area of ​​entry of the spinal nerves, outside the dura. A catheter is usually introduced that allows continuous administration of the anesthetic, this technique being used in deliveries and in the control of postoperative pain.

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

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3. General anesthesia

When general anesthesia is applied, the person who has been injected You will have a total absence of sensation in your whole body temporarily, accompanied also by loss of consciousness. This type of procedure is applied in complex interventions, in which it will be necessary to open the channel to the patient or that will be operated on several parts simultaneously.

As general anesthesia implies that the patient falls asleep in an induced way, not a few patients who have to undergo surgery are afraid of this procedure. Generally, anesthesia is safe, but it is true that it carries certain risks, especially in the case of general anesthesia. Among the problems that this type of technique brings with it we have:

• Arrhythmia
• Respiratory problems
• Allergic reaction to anesthesia

A striking symptom is delirium after general anesthesia. It is a picture in which the patient is confused, not knowing what is happening around him.

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 exactly what it is intended to avoid: being aware during the process. Some people can hear sounds while they are operated on and others, unfortunately, may feel pain during the operation. Although they are rare situations, living them is not pleasant at all.

Whatever the case, knowing what we are dealing with before undergoing surgery will help us to be calmer, and that is why below we mention the different phases of general anesthesia.

3.1. Induction

During induction, the anesthesiologist administers anesthetic medicine to achieve hypnosis, analgesia, amnesia, and relaxation.

As we have commented, in general anesthesia, consciousness is totally lost, a phenomenon that is calls it hypnosis and could be defined as being in a kind of coma induced via pharmacological. However, hypnosis does not mean that you do not feel pain, which is why it is necessary to also administer some type of pain reliever, usually derived from morphine.

Relaxation is induced by muscle relaxants, which are usually applied when the surgical intervention is going to require the patient's muscles to be relaxed or You have to put a tube into the windpipe to make sure that the person with surgery can continue to breathe while having it. operate.

Throughout this phase, the anesthesiologist team monitors the patient's vital signs to make sure everything is going well. It basically consists of verifying that the patient is still alive and does not have any seizures, evaluating oxygenation, ventilation and body temperature, among other parameters. To do this, sensors are placed on the patient's body that connect with monitors that analyze her physiological signals.

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3.2. Maintenance

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

This administration of anesthetic drugs can be done through the vein, which is called T.I.V.A (total intravenous anesthesia for its acronym in English), or also by inhaled route in which the drugs are applied through the device with which the patient is ventilating. patient. The combination of both anesthetic techniques is called balanced anesthesia.

3.3. Wake

Once the intervention has finished, the anesthesiologist team wakes up the patient. To achieve this, the supply of drugs by inhalation is first cut off and, if necessary, administer antagonists of anesthetics, substances that therefore instead of making the patient sleepy they wake up.

Once the patient has regained an adequate level of consciousness, the devices that have been used to control the ventilation and goes to the Resuscitation Unit, where her constant monitoring will continue until she has fully recovered her consciousness and functions.