Anesthesia has been used to aid the performance of surgery for a very long time. By the middle of the 20th century, doctors had begun to get a clear idea of the side effects of different types of anesthesia and had begun discouraging the use of others such as cocaine. However, there was still some blur when it comes to answering the question 'How does anesthesia work?'. Up to the late 18th century, operations were carried out with the patient being wide awake, and many would either die from the pain or resulting infections.
Modern anesthesia is safe as long as it is used in the right way and ideally by a professional. The purpose of anesthesia is to make the patient insensitive to pain, incapable of remembering the procedure (induced amnesia), able to relax and have muscle paralysis to prevent movement during the procedure.
How does Anesthesia Work?
The nervous system is a system of communication, and this is mostly disorganized. The use of anesthesia calms the nervous system and creates a kind of organization in the communication process of the system. Of course, this is also because some signals are being blocked and part of the normal nervous communication procedure is hindered. In this state, it is much easier to fall asleep as there is less ‘noise’ in the body.
The use of anesthesia on young children is discouraged as it can result in neurodegeneration. It can also result in the development of learning disorders in children.
Types of Anesthesia and How They Work Differently
Anesthesia enables patients to go through medical procedures that would otherwise involve intolerable pain. How does anesthesia work? Now you know it works by numbing the nervous system, but does all anesthesia work the same way? Doctors who use anesthesia on patients have to be thoroughly trained on how to administer the drugs as a slight miscalculation can result in death. The drugs are generally administered in a combination of three anesthesia agents: regional, inhalation and intravenous anesthesia.
Regional Anesthesia
Regional or local anesthesia simply blocks signals from the nervous system from reaching a certain part of the body. The drug may be administered through a nerve or bundle of nerves to block a small and specific part of the body supplied by the nerves, from being sensitive. It could also be administered on nerves near the spinal cord to block sensations in a whole region of the body such as the lower part of the body. This type of regional anesthesia, known as spinal anesthesia, needs to be administered very carefully and the patient must be closely watched as it can result in infection or damage of the nerves. The patient under this type of anesthesia is usually wide awake but desensitized on a part of the body.
Inhalation Anesthesia
Inhalation anesthesia is any drug that can be administered as an inhalant and usually affects the whole nervous system. The anesthetic is targeted at the brain. These are delivered through a mask or tube connected to a vaporizer and the anesthesia delivery system. Patients going through major surgeries are usually placed under inhalation anesthesia since these possess the properties of general anesthesia.
Intravenous Anesthesia
Intravenous anesthesia is a type of general anesthesia that is administered through injection. These drugs are usually used together with other types of anesthesia. Common intravenous anesthesia include propofol, ketamine, etomidate and barbiturates. Some barbiturates work for a very short time, and do not provide any relief from pain. However, they still make a patient unconscious. For this reason, they must be used together with other anesthetics.
Ketamine is less frequently used as it has some unpleasant side effects on patients after recovery. These could be vivid dreaming and having illusions.
Intravenous anesthesia are usually used to induce and maintain general anesthesia. General anesthesia affects the transmission of signals in the central nervous system.
Stages of General Anesthesia
How does anesthesia work? Does it make you fall asleep immediately? Not really, there're 4 stages of general anesthesia. Arthur Earnest Guedel, an American anesthesiologist, described the four stages of anesthesia in 1937. Though anesthesia has developed over all these years, the overall stages remain relatively the same. These stages are:
1. Induction
This is the stage where the patient develops amnesia. It is the period between the administration of the drug and the loss of consciousness.
2. Excitement
At this stage, the patient is fully unconscious. It involves a lot of excitement from the patient and the breathing rate might increase and decrease irregularly. Also, the patient’s body activity is delirious. Heart rate will similarly increase at this stage of excitement. This is the most dangerous stage of anesthesia as a patient experiences irregular breathing patterns. The real risk lies in the fact that the patient is likely to vomit and in the process of breathing irregularly, patients could easily get choked. Because of this, modern medicine has come up with strategies to reduce the amount of time spent in this stage of anesthesia.
3. Surgical Anesthesia
This is the stage where the patient starts experiencing a slowdown in his/her system. The patient first rolls the eyes and then has them in a fixed position. Pupils will dilate and the light reflex is lost. Breathing rate and heart rate go down, muscles are relaxed and body movements stop. The patient also stops vomiting.This is the stage at which the patient can be operated on. The goal of the surgeon is to get patients to this stage as soon as possible, and keep them there for the rest of the time that the operation will be done.
4. Overdose
At this point, the patient has had too much of the drug and experiences a collapse in the medulla or brain. Respiration and cardiovascular functions are also collapsed at this stage.
What to Expect after Anesthesia
After the surgery, the doctor will not ingest any more of the drug into your system. You will awaken soon after in the recovery room or in the operating room, and will likely be confused since you were unaware of any activities happening during the operation. You may also experience side effects and this will vary depending on the individual and the type of anesthesia used. The type of surgery that you went through will also determine the side effects you will experience.
Normally, you should experience nausea, vomiting, sore throat, drowsiness, shivering and hoarseness. Your mouth may also feel dry. Body pains are also common after anesthesia. Your doctor will prescribe medications for the side effects that you will experience.