Modern medicine is unthinkable without anesthesia. Even such a seemingly simple procedure as tooth extraction, without it, can cause real suffering to a person, and is even fraught with painful shock, not to mention more complex operations. But anesthesia appeared relatively recently – only in the 40s of the 19th century did one dentist demonstrate that ethereal gas can be used to make a person “pass out” before surgery and not feel pain. Until this moment, our ancestors had a hard time, because it is known that complex surgical interventions began to be performed thousands of years ago. Currently, there are many different types of anesthesia, and they act in different ways. However, scientists still do not fully understand the effects of many of them.
Modern medicine cannot be imagined without anesthesia, but its effect on humans is not fully known
< p class="toc_title">Contents
- 1 What is local anesthesia
- 2 What is general anesthesia
- 2.1 How does general anesthesia work
- 2.2 Consequences of general anesthesia
- 3 What is spinal anesthesia
What is local anesthesia
As you know, there are two types of anesthesia – local and general. True, there is another type of anesthesia that can be classified as a separate type – spinal, but we’ll talk about it separately. For minor operations, local anesthesia or sedation is most often used. For example, it is especially common in dentistry.
Unlike general anesthesia, local anesthesia does not put a person to sleep, but leads to numbness of a certain part of the body, while the person is conscious. The principle of action of local anesthetics is quite simple – they do not allow nerve cells to send signals to the brain. To do this, drugs stop the flow of sodium ions through channels in nerve cells.
This flow of ions, when intense enough, causes the neuron to send a signal to neighboring neurons. As a result, a chain of neurons sends signals to the brain. It must be said that the blocking of ions occurs gradually. The smallest nerve fibers are blocked first, and then the larger ones. For this reason, first a person stops feeling pain, and then the feeling of pressure.
Local anesthesia leads to loss of sensation in certain parts of the body where it is injected
Local anesthetic is considered the safest, but if too much of it is injected, convulsions, respiratory arrest and even coma can occur. In addition, some people may experience an allergic reaction.
What is general anesthesia
General anesthetics are used when performing complex operations. They are usually administered either intravenously as liquid medications or inhaled as a gas. The doctor chooses the anesthesia option himself, taking into account various factors. For example, inhalational anesthetics are often more suitable for children. In adults, the gas acts much more slowly, so drugs are used.
Often, when an adult loses consciousness after being given drugs, an inhalational anesthetic is used to maintain the necessary state of anesthesia. However, sometimes they do without gas at all.
How general anesthesia works
General anesthesia leads to loss of consciousness, immobility, blocking of pain, and amnesia regarding the details of the procedure. Although general anesthesia is widespread and has been used for a long time, the exact mechanisms of its action are poorly understood, which is why research is still ongoing.
General anesthesia leads to loss of consciousness
Most likely, blocking pain and discomfort is associated with molecular mechanisms. Depending on the type of drug, their principle of action may vary, but they all act on key receptors in the brain that have an anesthetic and sedative effect.
One of the most widely used anesthetics is propofol. It works by increasing the activity of a chemical neurotransmitter known as gamma-aminobutyric acid (GABA). GABA inhibits the neurons it connects to. By enhancing the effect of GABA in various parts of the brain, the drug leads to loss of consciousness.
Chloroform and isoflurane work differently. A study conducted on fruit flies showed that these drugs kill the insects by destroying fatty deposits in the membranes of their brain cells. At the same time, proteins are released that trigger various chain reactions inside the cells. One of these proteins suppresses the electrical and chemical activity of cells, rendering the brain unconscious. Presumably, these drugs have a similar effect on humans.
Scientists are working on creating drugs that quickly bring a person out of anesthesia
At the same time To this day, it is not completely known how general anesthesia causes a person to fall asleep, as well as how nerve circuits resume their work after anesthesia. However, it is known that anesthesia affects not only people, but also plants.
Effects of general anesthesia
The most common effects of general anesthesia are respiratory depression, memory impairment, sleep disturbances, headaches, hallucinations, hearing and speech impairment. Many of them persist only in the first hours after waking up. But there are more dangerous complications. For example, we also previously talked about how the use of anesthesia during childbirth can provoke mental illness.
The most dangerous complication from anesthesia is cardiac arrest during surgery. True, there is no complete proof that it is anesthesia that causes cardiac arrest. However, one study showed that statistically the risk of cardiac arrest does not depend on the type of anesthesia, but it is higher when using general anesthesia.
The most dangerous complication from anesthesia is cardiac arrest
When a patient is put under anesthesia, blood pressure decreases and remains low throughout the duration of the anesthesia. An overdose of anesthetic provokes a drop in pressure to a critically low level. In addition, anesthesia can cause various life-threatening changes in the functioning of the heart. However, in order to reduce the risk of dangerous consequences, doctors use an electrocardiograph to monitor the functioning of the organ and, if necessary, take the necessary measures in a timely manner, for example, reducing the dose of the substance.
But the risk of not waking up after anesthesia is a myth, since this cannot happen due to anesthesia. Tragic consequences are possible, but they arise for other reasons. As a rule, coma is caused by impaired oxygen delivery to the brain.
What is spinal anesthesia
Spinal anesthesia is a compromise between general and local anesthesia. It allows you to perform complex operations, but at the same time has a number of advantages – the person is conscious, he does not require observation in the post-anesthesia period, in addition, it has fewer contraindications and negative consequences.
Spinal anesthesia is safer than general anesthesia. Photo source: 24health.by
Spinal anesthesia is carried out by injecting a certain dose of local anesthetic into the cerebrospinal fluid. As a result, impulse transmission is blocked at the level of the spinal nerve roots. In this case, the person is actually paralyzed in the lower torso and lower extremities.
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For this reason, the use of spinal anesthesia is greatly limited. It is used when surgery needs to be performed on the lower torso, such as during a caesarean section. Perhaps further research in the field of anesthesia will make anesthesia even less dangerous and harmful. But for this, scientists need to fully understand how existing drugs work.