Types of anaesthesia
General anesthesia can be achieved in different ways. The different types of anaesthesia usually differ in the different drugs. Not every drug is suitable for every patient and every procedure.
The duration and type of procedure is decisive, as there are short-acting and long-acting medications. Possible intolerances and allergies of the patient must also be taken into account. For example, a distinction is made between gas anesthesia and total intravenous anesthesia.
The former cannot be used in the case of a certain genetic modification, as this can lead to malignant hyperthermia. Another distinction is the type of ventilation.For short procedures, ventilation with a mask is sometimes sufficient, while for long procedures a ventilation tube is necessary. General anesthesia can therefore be varied at many points and must be planned individually, which makes an exact classification into types almost impossible. This is what makes emergency anesthesia so dangerous, since planning cannot take place.
Anaesthetics
Anaesthesia consists of three different types of medication, as three major bodily functions need to be controlled. These functions are consciousness, pain perception and muscle function. The first group of drugs are sleeping pills or tranquilizers, which switch off consciousness.
These include propofol, thiopental and etomidate, for example. The second group are opioids, which eliminate the sensation of pain. These include fentanyl or ketamine, which have a much stronger effect than morphine.
The last group of drugs are muscle relaxants. These are intended to switch off the patient’s own use of the muscles so that ventilation and also movement of the muscles from the outside works better. Examples of muscle relaxants are succinylcholine or rocuronium.
Most anaesthetic drugs are administered directly via the blood, but anaesthetic gases can also be used. The best known anaesthetic gases are sevoflurane or isoflurane. During anaesthesia, the anaesthetist can additionally control the circulatory functions with medication.
Not every anaesthetic drug is suitable for every patient and every procedure, so the anaesthetist must plan anaesthesia individually. Emergency anesthesia therefore has significantly higher risks than planned procedures. Propofol is one of the strong sleeping pills and sedatives and can therefore be used to eliminate consciousness.
Propofol acts exclusively hypnotically and has no effect on the sensation of pain. The effect occurs very quickly and the half-life in the blood is short, which means that anaesthesia is possible to the minute. Serious side effects are rare.
Pregnancy or a soy allergy are reasons for exclusion from the use of Propofol. Special care must be taken with children. CO2 anesthesia usually does not mean an anesthesia in the classic sense, which is initiated by an anesthesiologist, but a deep unconsciousness due to too much CO2 in the blood.
This can be caused both by the body’s own processes and by external influences. A CO2 narcosis due to the body’s own CO2 can result from poisoning with drugs or medicines, but also from a chest injury or severe overweight. These three causes have in common reduced breathing and thus an accumulation of CO2 in the blood.
Another cause is poorly controlled artificial respiration. This can be caused by various regulatory mechanisms of the body, which have an undesirable influence on ventilation. Especially the high-percentage oxygen supply can influence the CO2 output of the body via different systems.
A poisoning with CO2 from outside can occur through accidents. Examples are the accumulation of CO2 in fermenting cellars or silos. Targeted CO2 narcosis is not used in medicine and is only known from animal slaughter.
Anaesthetic gases, medically also called inhalation anaesthetics, are used to induce and maintain general anaesthesia. The aim of these drugs is to switch off consciousness, pain perception, reflex mechanisms and muscle relaxation. Another effect of the anaesthetic gases is a deliberate memory gap of everything that happens during the administration of the gases (amnesia).
There are several different substances which are used as anaesthetic gases in Germany. Two groups of substances can be distinguished, which differ in their aggregate state at room temperature. Xenon and laughing gas are gaseous at room temperature whereas the so-called volatile anaesthetics are in liquid form and have to be administered via a vaporizer.
The usual agents in this group of substances are isoflurane, sevoflurane and desflurane. The effect of anaesthetic gas can be attributed to a high binding of fatty substances (lipophilicity). This means that the gases can be easily transferred into the blood after inhalation and their concentration can be controlled.
The gases accumulate mainly in fatty tissues, such as the brain.This is advantageous because the mechanisms of consciousness to be controlled are controlled from there, and thus the effect of the anaesthetic gas occurs quickly. The exact mechanism of action of anaesthetic gas is not completely understood. However, reactions at the cell walls and ion channels are discussed and suspected.
In modern anaesthesia, different anaesthetics are usually used to minimize the side effects of one substance by another drug. The side effects of anaesthetic gas cannot be generalized, as they differ from drug to drug. However, all substances have in common that they can cause a life-threatening metabolic derailment with an accompanying rise in body temperature (malignant hyperthermia) as a side effect.
Despite the rarity of this side effect, it is a very dreaded complication of any anesthesia under inhalation anesthetics. Other side effects include dose-dependent damage to the heart muscle, vessels and respiratory tract. Elimination in the liver can also cause liver damage. The anaesthetic gas is removed from the body by breathing out the gas when the operation is finished and the patient is to be awakened again.
