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General anesthesia, commonly known as anesthesia, means complete and reversible loss of consciousness caused by the introduction of anesthetic drugs. They induce sleep (hypnosis), amnesia (amnesia), analgesia (analgesia), and inhibition of spinal reflexes (areflexia) and muscle tone. Thanks to this, it is possible to perform painless surgeries.

General anesthesia , colloquiallynarcosis , temporarily inhibits the central nervous system, but keeps the patient alive. The doctor administering anesthesia isanesthesiologist , the drugs administered areanesthetics , and the entire medical specialization is anesthesiology. The following phases of anesthesia are distinguished - introduction, maintenance and removal. They depend on the patient's age, type of surgery, comorbidities, and the experience of the anaesthesiologist.

General anesthesia (narcosis): medications used (anesthetics)

Due to the method of administration, anesthetic drugs are divided intointravenous anestheticsandinhalation anesthetics . Intravenous anesthetics are divided into:

  • hypnotics (benzodiazepines (e.g. midazolam), barbiturates (e.g. thiopental), etomidate, ketamine, propofol)
  • opioids (fentanyl, alfentanil, sufentanil, remifentanil, morphine)
  • muscle relaxants (atracurium, cis-atracurium, pancuronium, rocuronium, vecuronium and succinylcholine)

Inhalation anesthetics include:

  • nitrous oxide
  • desfluran
  • enfluran
  • isoflurane
  • sevofluran
  • halothane

It is worth knowing that an ideal anesthetic should quickly cause unconsciousness, show an analgesic effect, provide stabilization of the circulatory system, relax muscles and not cause respiratory depression and not accumulate in the body.

General anesthesia (narcosis): types

There are inhalation, intravenous and complex anesthesia.

Inhalation anesthesia- anesthetic gases are used for insertion and maintenance. Anesthesia is induced by administering gas - most often sevoflurane, which is not irritating to the respiratory system. On the other hand, an inhalation anesthetic in a mixture of oxygen and air is used to maintain anesthesia.Anesthesiaintravenous- both induction of anesthesia and maintenance of anesthesia are carried out thanks to intravenous drugs. All intravenous anesthetics can be used for the introduction, while propofol is most often used for maintenance. In addition, it is also possible to use hypnotics, analgesics and, if necessary, relaxants.Complex anesthesiais currently the most commonly used anesthesia. To carry out it, it is necessary to use inhaled and intravenous drugs. This allows you to limit their dose, and thus reduce their toxicity and the risk of side effects.

How is general anesthesia (narcosis) going?

  • introduction

Before induction of anesthesia, the patient should be monitored - the electrodes for the ECG, the pulse oximeter (informs about the saturation of arterial blood with oxygen and the pulse) and the blood pressure cuff are placed. Then, for about 2-3 minutes, the patient is administered 100% oxygen through a mask. This is calledpre-oxygenation- it provides the patient with an oxygen reserve in the event of difficult intubation. In the next stage, an intravenous drug is administered (barbiturate, etomidate, propofol), but sevoflurane may also be inhaled.

It is worth remembering that before complex anesthesia, an opioid analgesic is administered beforehand - most often fentanyl. After the ciliary reflex has disappeared, the breath is manually guided through the mask. If it is effective - a relaxant is given. The aim is to relax the muscles of the mandible, pharynx and larynx, which allows the patient to be intubated. Until the muscle relaxant becomes active, a replacement breath is performed manually through the mask. After 1-3 minutes, the patient is intubated. After intubation, the position of the endotracheal tube is determined by auscultation of the lungs and checking the capnography curve. The endotracheal tube is then attached and the patient connected to the ventilator.

  • support

To maintain anesthesia, the anesthetic is administered by inhalation or intravenous injection. In addition, depending on the patient's accompanying diseases and the extent of the procedure, monitoring can be extended to include central venous pressure, invasive blood pressure measurement or insertion of a urinary catheter. Then the patient is placed on the operating table - according to the operation that will be performed. Before the skin operator incision, the anesthesiologist usually deepens the anesthesia - it depends on the individual needs of the patient and the type of surgical stimulus. It's good to know that symptom tooof light anesthesia is tachycardia, increase in blood pressure, self-breathing, sweating, tearing, pupil dilation or spontaneous movements.

  • derivation

At the end of the operation, the administration of intravenous anesthetics is gradually reduced - the concentration of anesthetic gases is also reduced until the supply of anesthetic gases is completely shut off. At the same time, the supply of fresh gases is increased and the patient uses 100% oxygen-controlled breathing. Additionally, in some patients it is necessary to use drugs that reverse the effect of previously administered muscle relaxants. When the patient is already breathing, the excess secretions from the oropharynx are sucked out and the endotracheal tube is removed. After these activities, the patient is transported to the so-called the wake-up room in order to observe him and exclude the presence of possible complications that may threaten his life.

General anesthesia (narcosis): complications

Agentsof general anesthesiaaffect the entire body, so their side effects can be limited or systemic.

The most common complications of general anesthesia include respiratory and circulatory complications.

In the event of respiratory complications,hypoxia (hypoxia)is usually present. It is the result of abnormal breathing on the mask. It is manifested by a decrease in saturation, cyanosis and tachycardia or bradycardia. If left untreated, it leads to death.

Another respiratory complication ischoking(aspiration of gastric contents). Most often it is caused by vomiting during induction of anesthesia. It manifests itself as bronchospasm, a decrease in saturation, and finally pulmonary edema. It is worth remembering that choking can also occur during surgery (asymptomatically), and also during recovery from anesthesia.

The cause of cardiovascular complications is usuallyblood lossand overdosing or underdosing of the medications administered. These complications are most common in the form of a drop in blood pressure, tachycardia, and even asystole.

The next group of complications of general anesthesia are injuries related to the positioning of the patient on the operating table - they usually concern the eyes and the brachial plexus, and may manifest themselves withvisual impairmentandnerve palsy .

In addition, another relatively common complication istooth damageduring intubation.

Don't forgetanaphylaxis , which occurs at a frequency of 1: 6,000 to 1: 20,000 anesthetized patients. It can actually be triggered byany drug, but most often they are caused by muscle relaxants, contrast agents, and also antibiotics. It can manifest itself as hives on the skin, but also as a shock ending in cardiac arrest.

A very serious, but at the same time rare (occurs in 1: 50,000-1: 100,000 adults) complication of general anesthesia is hyperthermiamalignant . This disease is inherited autosomal dominantly and results from a defect in skeletal muscle metabolism, which is associated with a disturbance of the calcium metabolism of the cell. The triggering factor causes all striated muscles to stiffen, to a sharp increase in body temperature and blood pressure, hypoxia, hypercapnia, and finally lactic acidosis and rhabdomyolysis with myoglobinuria and crush syndrome. The mortality rate of this complication is approximately 15%. It is worth remembering that all inhalation anesthetics and succinylcholine, as well as alcohol and other stimulants are among the factors that trigger malignant hyperthermia.

Read also:

  • Local (regional, peripheral) anesthesia
  • Epidural
  • Anesthesia at the dentist's
  • Sedation

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Category:

Neurology