Anesthesia is a fundamental technique for any surgical intervention. The world of modern medicine, and in particular of surgery, would be unthinkable if it weren’t for the different types of anesthesia currently in use, both for gentle procedures like dental filling and for more complex procedures like gastric bypass surgery.
Anesthesiologists use different methods so that the patient does not feel any pain during the surgery. Let’s see what are the main types of anesthesia and what they are used for.
The main types of anesthesia (classified)
Many people, when they hear the word anesthesia, first think that it is a numbing substance, capable of making the person who was administered to it unconscious. This idea is partly true, but it must be said that anesthesia refers to all the techniques and technologies used to prevent pain in the patient both during open heart surgery and to reduce the discomfort that he can have in his daily life, like a burn. sensation in the eyes or sore throat.
Anesthetic substances can be administered by injection, inhalation, topical lotion, aerosols, skin patches or eye drops., and its main purpose is to cause loss of sensitivity, either in a particular area or throughout the body.
In the latter case, the usual thing is that the patient not only does not feel pain in the place of the body, but also loses consciousness.
The type of anesthesia that will be used will depend on different factors, among which we highlight:
- Types of surgery
- Area to operate
- Duration of the operation
- Current and previous clinical picture
- Possible patient allergies
- Pre-anesthetic reactions (both for the patient and his family)
- Medications the patient is taking
- Age, height and weight
We will see what are the main types of anesthesia.
1. Local anesthesia
Local anesthesia is a type of medicine that works only on a small part of the body, and anesthetic medicine is applied to prevent pain. This may be topical anesthesia if the medication is applied as drops (eyes), spray (throat) or paste (skin), or as an infiltration if injected with a syringe and needle into the area. to operate.
The duration of the effects of the local anesthetic will depend on several factors, including:
- Types of anesthetics (for example, bupivacaine, lidocaine …)
- Total dose: in addition the dose acts earlier and lasts longer its effect.
- If adrenaline is added (vasoconstrictor which prolongs the elimination of the drug).
As a rule, the effects of a local anesthetic usually last between half an hour and two hours.
2. Regional anesthesia
Regional anesthesia it affects a larger area compared to local anesthesia. In this case, it involves applying an anesthetic drug that causes numbness in a specific area, such as an arm, a leg, or the lower half of the body.
Depending on the area to be treated, different techniques can be used:
2.1. Anesthesia of the trunk and plexus
If the operation involves 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: trunk and plexus.
The difference between trunk and plexus anesthesia is that in the first the anesthetic is injected into one nerve, while in the second the anesthetic is injected into several nerves involved.
2.2. Spinal and epidural anesthesia
Another regional anesthesia technique used by anesthesiologists it consists of piercing the back and injecting the anesthetic into the area close to the spine, through which nerves enter the spinal cord to send pain sensations to the brain.
The use of this technique blocks the transmission of these sensations and the person does not have the sensation of pain. Within this modality, we find two variants.
Under spinal or intrathecal anesthesia, the needle passes through the dura which is the protective covering of 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 if dissolved substances are found, such as anesthesia, it takes them to the central nervous system.
On another side, in the technique of epidural anesthesia the needle does not cross the dura. In this case, the anesthetic substance remains in the area where the nerves of the spinal cord enter, outside the dura. A catheter is usually introduced which allows for continuous administration of anesthetic, this technique being used in parts and in postoperative pain control.
In all regional anesthesia techniques, also called locoregional anesthesia modalities, the patient is awake. during the procedure. However, you will not feel any pain during the process as you are under the effects of anesthesia that will have been injected into one or another area of your body that will be treated surgically.
3. General anesthesia
When general anesthesia is applied, the person who has been injected he will have a total lack of feeling all over his body temporarily, also accompanied by loss of consciousness. This type of procedure is applied in complex interventions, in which the patient will have to be opened in a canal or which will be operated in several parts simultaneously.
Because general anesthesia involves making the patient fall asleep, there are quite a few patients who are due for surgery who 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 associated with this type of technique are:
- Respiratory problems
Allergic reaction to anesthesia
A striking symptom is delirium after general anesthesia. It is an image in which the patient is confused and does not know what is going on around him.
This type of delirium occurs mostly in patients over the age of 60 who have just had surgery to show puzzling signs for days after surgery. It can also occur in children upon waking from anesthesia.
Another problem with anesthesia is exactly what you want to avoid: being aware during the process. Some people may hear sounds during the operation and others, unfortunately, may experience pain during the operation. Although these are rare situations, going through them is not at all pleasant.
Either way, knowing what we are facing before having the operation will help us be more relaxed, which is why we discuss the different phases of general anesthesia below.
In induction, the anesthesiologist administers the anesthetic drug to achieve hypnosis, analgesia, amnesia and relaxation.
As we mentioned, under general anesthesia consciousness is completely lost, a phenomenon called hypnosis and could be defined as being in a kind of pharmacologically induced coma. However, hypnosis does not mean that you do not feel pain, which is why a certain type of pain reliever, usually derived from morphine, should also be given.
Relaxation is induced by muscle relaxants, which are typically applied when the patient’s muscles need to be relaxed during surgery or a tube needs to be placed inside the trachea to ensure that the operated person can continue to breathe during surgery.
Throughout this phase, the anesthesiologists team monitors the patient’s vital signs to make sure all is well. It basically consists of checking that the patient is still alive and has no seizures, and oxygenation, ventilation and body temperature are assessed among other parameters. For this reason, sensors are placed around the patient’s body that connect to monitors that analyze their physiological signals.
Once the induction phase is finished, comes the maintenance phase. In this necessary drugs continue to be administered so that the operation can be performed safely.
This administration of anesthetic drugs can be done intravenously, what is called TIVA (total intravenous anesthesia for the acronym in English), or by inhalation in which the drugs are applied using the device with which we ventilate the patient. The combination of the two anesthetic techniques is called balanced anesthesia.
3.3. To wake up
Once the operation is completed, the team of anesthesiologists wakes the patient. To achieve this, the drug supply is first cut off by inhalation and, if necessary, anesthetic antagonists are administered, substances which therefore wake the patient instead of lulling the patient.
Once the patient has regained an adequate level of consciousness, the devices used to control ventilation are removed and he goes to the intensive care unit, where the constants will continue to be monitored until he is completely recovered consciousness and functions.
- Bonofillio, FC; Casais, MN (2006). They’re going to numb me. Answers to your questions about anesthesia. Buenos Aires: Editions on the hospital.
- Pinos, T. (1997). Chapter IV: Birth of the queen. Medical facts. Planet. p. 57-66.