The anesthesia
General anesthesia
The nineteenth century, a turning point in medicine. In 1846, J. Warren first used ether as an anesthetic in an operation.
Just a few years earlier, the great French surgeon Velpeau wrote "Avoiding pain during operations is a chimera that can no longer be pursued."
The technique of ether anesthesia spread from America to Europe.
Less than a year after this discovery, chloroform was used in obstetrics. This more volatile inhalation gas, more pleasant than ether, was now the method of choice for surgical procedures.
Despite considerable side effects, the two volatile gases were used by us until the sixties of the last century.
What is general anesthesia?
General anesthesia is the form of anesthesia in which both the wakefulness of the patient and his pain perception are completely switched off.
How does general anesthesia work?
The drugs required for general anesthesia are either injected into a vein, which is called intravenous, or given to the patient through a mask. In the latter case, he absorbs them through the airways, i.e. inhalatively.
The drugs used for general anesthesia work in the central nervous system. This effect is characterized by the following features:
- Freedom from pain
- Loss of consciousness
- Memorylessness
- Damping of the autonomic nerve reactions
None of the available drugs alone can produce all of the components of general anesthesia. Therefore, a combination of different drugs is always used.
Some operations are only possible if complete relaxation of the voluntary muscles is also ensured.
What is general anesthesia used for?
Anesthesia enables all kinds of operations to be carried out.
Its purpose is that the patient does not feel any pain and does not experience the operation. Many types of surgery can only be performed under general anesthesia.
For others, general anesthesia is an alternative to partial anesthesia, known as regional anesthesia.
The achievements of modern surgery would not have been possible without simultaneous developments in anesthetic techniques.
What should be considered before a general anesthetic?
If it is certain that an operation or examination should take place under general anesthesia, the anesthetist will talk to the patient to prepare for the anesthesia. This conversation has several purposes:
- The anesthetist can get an idea of the patient's medical history and state of health.
- The patient is informed about the appropriate form of anesthesia, the procedure and the risks.
- The scope of the examinations is determined to clarify the risk of anesthesia.
- The night before an operation, many patients are understandably excited. It is therefore recommended that the anesthetist prescribe a sedative.
It is particularly important that you, the patient, have been sober for several hours before the anesthesia, i.e. have not eaten, drank or smoked.
How is general anesthesia performed?
On the day of the operation, the patient is taken to the anesthesia preparation room. There he is given intravenous medication via a cannula to prepare himself and to actually fall asleep.
After falling asleep gently, a breathing tube, the tube, is inserted through the mouth into the windpipe, through which the patient receives oxygen and anesthetic gases during the anesthesia. The patient does not feel anything from the insertion of this ventilation tube - this process is called intubation. Intubation can be dispensed with, particularly in the case of brief general anesthesia. The patient is then ventilated through a mask.
After intubation, various drugs are administered to maintain anesthesia for the duration of the operation.
The anesthetist monitors the cardiovascular situation, ventilation and fluid balance of the patient during the entire period. This process is called monitoring. There are other methods of monitoring, depending on the extent of the operation and the patient's health. If they are necessary, the anesthetist will discuss them with the patient before the operation.
The depth of anesthesia is shown in the behavior of blood pressure and pulse and is controlled depending on the operation. When the end of the operation, the anesthetist will also stop administering the anesthetic medication. As a result, the patient begins to wake up just a few minutes after the end of the operation.
The removal of the ventilation tube, the so-called extubation, usually takes place before the patient is fully awake. As a result, the patient does not feel anything of this process.
After extubation, the patient is monitored in the recovery room for a while. He is also already receiving medication for the pain. As soon as his circulation is stable and he himself is free of pain, he can be brought back to the ward.
After major operations or in patients with poor health, it may be necessary to transfer the patient to an intensive care unit after the operation.
In some of these patients, the anesthesia is continued until the body functions are finally stabilized.
The patient wakes up later in the intensive care unit.
What complications can occur with general anesthesia?
When it comes to the risks of general anesthesia, a distinction must be made between general risks that exist with general anesthesia and special risks that arise from the severity of the operation or the patient's state of health.
General risks include, for example:
- Disorders of the cardiovascular system
- Ventilation problems
- Damage to the front teeth during intubation
- Allergic reactions to given anesthetics
These risks rarely occur.
Sensitive people may experience nausea and vomiting in connection with anesthesia. In order to prevent large amounts of stomach contents from flowing into the lungs in this case, you as the patient must be absolutely fasted before the anesthesia.
The dreaded waking up of many patients during the operation without the surgeon or anesthetist noticing it, is very rare. In the cases in which this has occurred, there were predominantly special anesthetic situations.
On the other hand, the special risks resulting from the severity of the operation or from poor health can significantly increase the individual risk of anesthesia.
In order to recognize such complication possibilities and, if necessary, to determine additional monitoring or medication administration during the anesthesia, the anesthetist needs all available information from the patient when preparing for the anesthesia. From this he can estimate the individual risk and discuss the necessary measures.
What are the alternatives to general anesthesia?
For some operations, a local anesthetic, the regional anesthesia, is possible as an alternative. The anesthetist will point out these options during the interview to prepare for the anesthesia, if this alternative makes sense.
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Nausea and vomiting after general anesthesia
The Ruhr University Bochum has now presented the results of a study on nausea and vomiting after surgery under general anesthesia. This aftereffect is known as PONV (English: postoperative nausea and vomiting).
215 patients were asked about their condition before the operation and during the first 24 hours afterwards.
Nausea appeared in 14.9 percent of the cases. 4.7 percent of the patients reported that they vomited.
Women are therefore four to five times more likely to have these after-effects.
Even those who have previously felt nausea after an operation under general anesthesia or suffer from motion sickness may not tolerate general anesthesia so well.
The fear of the operation is also a risk: a third of the patients who stated that they were very afraid of the operation suffered from nausea and vomiting afterwards.
If it is known before the operation that the patient has an increased risk of PONV, another form of anesthesia may be chosen, such as spinal anesthesia. It is also advisable to administer medication to reduce the frequency and severity of the nausea. (Personal note - 2021: I learned from an anesthetist that it is the anesthetic gas that causes 80% nausea in women and 10% in men. Unfortunately, I also belong to this species.)
Operations under general anesthesia are very safe today: in the 1940s, on average, every thousandth patient died of complications from anesthesia; today there are only four out of a million operated on.
Copyright 2003 Qualimedic AG
Anesthesia - safe deep sleep?
Limit of perception
Modern anesthesia controls the wakefulness, freedom from pain and muscle relaxation at the same time
Since the hearing is still partially functional even under anesthesia, noises can help develop gentler anesthesia with less risk. The basic idea sounds simple, but the technical implementation is complicated.
Narcotics have been used for centuries
Stress on the body
Anesthetics have been used for centuries to ensure that people experience as little pain as possible during an operation.
General anesthesia in particular posed serious risks to the body.
Whether ether, chloroform or morphine, the more effective the numbing effect, the more severe the side effects.
Surveillance in the operating room
An anesthetic consists of three parts.
Today, in general anesthesia, many different drugs are used at the same time in order to carry out the various tasks as gently as possible:
First, they suppress pain, second, they make the patient unconscious, and third, they relax the muscles.
In the modern operating theater, these three factors are monitored and regulated at all times.
The fact that the anesthesia wears off too early only happens in extreme individual cases
Every patient's nightmare.
But what happens when the anesthetic wears off too early, the anesthetic fails and the body is paralyzed by the muscle relaxants? Fortunately, this nightmare only happens in extremely rare individual cases.
In a study in which several German clinics were involved, 60 patients who had awakened during an operation were recently examined.
The main focus was on how much people had perceived what was happening, whether they suffered fear or pain in the meantime and what late effects they had suffered from it.
"Intraoperative waking episode" a feeling of paralysis and fear
Limit of consciousness.
All patients were able to hear, and most of them could even remember conversations in the operating room. Many also stated that they had seen something.
According to the study, few patients experienced paralysis, helplessness and fear during the "intraoperative awake episode".
Nevertheless, around half of the patients suffer from long-term effects, even if only a few still need medical treatment. No study can describe the torments they went through.
The patient hears noises through an earphone. At the same time, it is observed whether the EEG shows a change in brain waves.
Recognize the signs!
Protection against intraoperative awakening is made more difficult by the fact that the patient's level of alertness could previously only be determined with certainty by measuring brain waves, pulse, blood pressure, etc.
A simple trick should now ensure complete safety: Clicking noises are played to the patient via an earphone and at the same time it is observed whether there is a change in the EEG (the pattern of electrical activity in the brain).
In fact, even under deep anesthesia, sounds still lead to reactions in the brain, although the patient no longer perceives them.
These EEG changes with different depths of anesthesia are very small, but the researchers can now see the first signs of awakening.
In the future, this procedure will enable anesthetists to take countermeasures even earlier.
Link & Download on the topic
Anaesthesia Antiques Bochum - online Museum
