Intravenous anesthesia is a state of inhibition of the central nervous system caused artificially by introducing narcotic drugs into the human body, accompanied by a loss of consciousness, relaxation of the skeletal muscles, weakening or switching off of some reflexes and the disappearance of pain.
Used during surgery. In Israeli clinics, specialists use the latest generation of drugs that provide the necessary effect on the patient’s body.
Effect of intravenous anesthesia
The main advantage of this type of general anesthesia, compared to other types, is its immediate effect, which is practically not accompanied by a stage of excitement, and the same rapid recovery of the patient from the effects of the drugs administered to him.
Depending on the drug administered, one dose of the drug, on average, renders a person unconscious for 20 minutes. Based on this, if the operation is carried out over a long period of time, the anesthesiologist gradually adds the required amount of medication to prolong the patient’s unconscious state.
Intravenous anesthesia, from a technical point of view, is a very simple procedure that provides a very fast and reliable result. But in this case, complete relaxation of the muscular system cannot be achieved and the risk of drug overdose is quite high. Based on this, during long-term operations, a combined anesthesia of several types is mainly used. Intravenous is an introductory one, bringing the operated person into an unconscious state without the occurrence of a stage of excitation. Intravenous mononarcosis is used extremely rarely.
Features and Benefits
The tolerability of different types of anesthesia is individual, therefore, based on the specific characteristics and depending on the condition, the type of general anesthesia is selected separately for each patient. Also, the type of anesthesia depends on the type and size of the surgical procedure. For example, in gynecology, for short-term manipulation lasting 15-20 minutes, it is preferable to use intravenous anesthesia. Its advantage is that the introduction of anesthesia occurs quickly, without unpleasant sensations or consequences on the part of the patient. Awakening after such anesthesia occurs within a few minutes and is easier to tolerate. Unlike the mask type, there is no excitation phase, which simplifies the work with the patient. The effect of such anesthesia is short-lived (about 15 minutes), so if there is an unscheduled increase in the operation time, it is necessary to increase the dose of anesthetics.
Intravenous anesthesia
Please note: the most common types of surgical operations in gynecology are curettage of the uterine cavity and abortions. They take from 20 to 40 minutes. For long-term operations, combined anesthesia is used, which consists of mask and intravenous anesthesia.
For long-term surgical procedures, it is better to use combined anesthesia, which may include parenteral anesthesia and inhalation. So, intramuscular and mask anesthesia can be used simultaneously.
Intravenous anesthesia indications
Almost any patient's condition that requires immediate (emergency) or planned surgical intervention is an indication for the use of intravenous anesthesia. Preference is given to operations that do not take much time. Otherwise, the type of anesthesia is selected individually, taking into account the patient’s condition.
Use of general anesthesia if there are contraindications
General anesthesia can hardly be called harmless, since it has a systemic effect on the body and can provoke serious complications in the functioning of the cardiovascular system in a person, causing nausea, headache and other unpleasant symptoms. But there is no need to be afraid of it if the anesthesiologist, despite the presence of contraindications, allowed the patient to undergo surgery.
An experienced doctor can minimize the harm from the effects of general anesthesia on the body, so the patient can and should trust him and not worry about anything. Refusal to undergo surgery can lead to more disastrous consequences than the effects of anesthesia.
The above restrictions on the use of general anesthesia do not apply to emergency cases when a person’s life depends on a timely operation. In such a situation, surgery using general anesthesia is carried out regardless of whether the patient has contraindications to it or not.
Contraindications to the use of intravenous anesthesia
If emergency surgery is necessary, there are no absolute contraindications for intravenous anesthesia. Israeli anesthesiologists will select the type of medications that will have the most gentle effect on each individual organism.
Read! What is an anesthesia card?
In the case of a planned operation, there are several contraindications to this type of anesthesia:
- Disruption of the cardiovascular system - severe heart rhythm disturbances, myocardial infarction, if little time has passed since the onset of its development (less than a month), stable or unstable angina, characterized by a severe form of the course, heart failure (uncompensated).
- Acute diseases of the nervous system.
- Acute infectious diseases of the respiratory tract, in particular bronchial asthma during exacerbation, pneumonia, acute bronchitis or chronic bronchitis in the acute stage.
- Infectious diseases.
In addition to contraindications of this nature, there are also contraindications to the use of one or another drug used during anesthesia. Each drug has its own. Individual intolerance of an individual organism to barbiturates administered as an anesthetic should not be excluded. If there is one, a disruption of the cardiovascular system or the functioning of the respiratory system may develop. Based on this, during each operation there are all the necessary drugs and devices to normalize the functioning of the patient’s organs and ventilation of the lungs.
Disadvantages and contraindications
For intravascular anesthesia, narcotic drugs are used, for example, derivatives of barbituric acid; their long-term use is unacceptable, as it causes severe respiratory depression. They are administered in small doses (100 ml of 1% solution) and normally act for a short time (15-20 minutes). In view of this, it is necessary to have a ventilator available for use in case of apnea. The use of barbiturates is contraindicated if there is a risk of shock, collapse, severe respiratory failure and anemia. Other drugs such as: sodium hydroxybutyrate (10-15 g/kg), sombrevin (10mg/kg), ketaral (2-5 mg/kg) and Viadryl (15 mg/kg) are dangerous due to the development of such consequences as phlebitis and thrombophlebitis, hypotension and hallucinosis. The main contraindication is an allergic reaction to the components of the drugs. However, in gynecology it is better to give preference to intravascular anesthesia over local anesthesia.
Important: before surgery, if it is not an emergency, it is necessary to undergo an examination of organ systems. The type of anesthesia will depend on the functional state of your body.
General contraindications for anesthesia are acute untreated conditions and depletion of body systems. Such conditions include acute infectious diseases, severe rickets, acute neurological conditions, exacerbations of chronic pulmonary diseases and others. Even a short-term effect of drugs can critically aggravate the patient’s condition and lead to serious consequences. In gynecology, intravenous anesthesia is more often used than mask anesthesia. Intra-arterial administration of anesthetics leads to quick results, but in a certain situation, contraindications carry more weight and it is better to protect yourself and the patient from serious consequences.
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Drugs used for intravenous anesthesia
To carry out this type of anesthesia, various intravenous anesthetics are used: natural brain metabolites, steroids, barbiturates and their derivatives:
- propanidide;
- Viadryl;
- ketamine;
- sodium hydroxybutyrate.
All types of intravenous anesthesia have a pronounced hypnotic effect on the patient’s body, as well as a narcotic effect with a weakly expressed analgesic effect. They provide a quick and pleasant sleep for the patient and do not cause arousal. Therefore, they are an ideal option for induction of anesthesia. If their concentration exceeds the required norms, the respiratory center is depressed and a depressive state develops.
When this group of drugs is administered intravenously, only 1/3 of the drug has a narcotic effect on the patient’s body. The remaining 2/3 binds to plasma proteins. Based on this, patients characterized by hypoproteinemia may develop too deep anesthesia. Protein binding depends on how quickly barbiturates enter the blood. The faster their introduction, the greater the connection with proteins. Therefore, in order to avoid complications of intravenous anesthesia, such drugs are administered extremely slowly.
Read! Advantages of endotracheal anesthesia
Features of drugs used for intravenous anesthesia
- Barbiturates (metahexitone, sodium thiopental, hexonal). They are used to obtain basic anesthesia. Undesirable consequences of the administration of these drugs include inhibition of the patient’s cardiac and respiratory activity.
- Ketamines. They have clear advantages over other drugs, namely the absence of a depressing effect on the cardiac and respiratory systems. Used by anesthesiologists for both introductory and main anesthesia. During the patient's recovery from anesthesia, loss of coordination of movements and severe hallucinations may occur.
- Viadryl, sodium hydroxybutyrate, propanidide. These drugs are mainly used for induction of anesthesia with the use of other drugs.
How is intravenous anesthesia done?
Carrying out intravenous anesthesia is a simple, from a technical point of view, procedure that gives an almost immediate effect. The patient falls asleep calmly, bypassing the stage of excitement. But such anesthesia does not provide complete muscle relaxation, which increases the risk of overdose. One dose of the drug turns off the patient's consciousness for about 20 minutes, so if the surgery lasts longer, then an additional dose is required. Typically, for long operations, intravenous anesthesia is used in combination with inhalational anesthesia in order to initially calmly immerse the patient in an unconscious state without the stage of excitement.
Preparing for intravenous anesthesia
Before administering anesthesia, the patient must be prepared. In order for the anesthesia to be of high quality and without consequences, the following measures must be taken:
- conversation with the patient about how the procedure will take place (if any questions arise, it is better to clarify all points in advance);
- for a certain period of time before the operation, the patient is limited in the consumption of food and drinks;
- hygienic procedures (sometimes a cleansing enema, at the request of the doctor);
- premedication on the eve of the intervention is carried out to reduce the patient’s anxiety and reduce the likelihood of allergic reactions.
Classification of intravenous anesthesia
There are 3 types of this type of anesthesia, each with its own characteristics:
- Central analgesia is produced by administering a combination of narcotic analgesics; it provides a good degree of pain relief, but at high doses respiratory depression occurs, so the use of mechanical ventilation is often required.
- Neuroleptanalgesia provides neurovegetative inhibition, loss of pain sensitivity and psychological peace, but the patient is conscious.
- Ataralgesia is usually used as a component of combined anesthesia, based on the use of analgesics in combination with tranquilizers.
Depending on the type of surgery, the patient’s condition and some other factors, a certain type of intravenous anesthesia is used.
Carrying out intravenous anesthesia
Intravenous anesthesia is carried out after completion of all preparatory measures, immediately before the start of surgery. The patient is placed on the operating table, a vein is punctured and an anesthetic drug is slowly injected. After administering the first 3-5 ml, pause for about 30 seconds, while observing the reaction and condition of the patient, then continue administering the drug until the ciliary reflex disappears. The consumption of anesthetic depends on many factors:
- patient weight;
- floor;
- age;
- general condition and nature of the underlying disease;
- size of fat depots;
- liver condition, etc.
The anesthesiologist calculates the dose of the drug in each case individually, having carefully studied the patient's medical history and condition.
Throughout the anesthesia, the patient is constantly monitored and breathing, pulse rate, and blood pressure are monitored. After waking up the patient, the doctor must assess his condition: check his reflexes, make sure that the patient is conscious. Then the patient enters secondary sleep, which is why it is so important for the doctor to record the patient’s recovery from the state of anesthesia. During this period, dizziness, nausea, and vomiting may sometimes occur.
