Measures to determine anesthesia

The article is expertly consulted by an Anesthesiologist, anesthesiologist, anesthesiologist - Department of General Surgery & Anesthesia - Vinmec Hai Phong International General Hospital.

Determining the level of anesthesia is an important job during anesthesia to ensure safety in surgery and the life of the patient. This procedure is determined mainly by clinical observation, EEG and anesthetic concentration measurement.

Anesthesia is a procedure applied to help patients relieve pain during painful procedures that normal people cannot tolerate, especially surgery. Anesthesia is performed by injecting anesthetic into the body until the patient loses consciousness, then gradually reducing the drug concentration when the surgery is completed.
In 1846, after presenting the anesthetic effect of ether, Morton was recognized as the first inventor of anesthetic therapy. In 1847, after applying ether to surgery, Plomley described the three stages of anesthesia as poisoning, stimulation, and deep anesthesia. Seven years later, John Snow described five periods of anesthesia with ether and chloroform with signs of conjunctival reflexes, breathing patterns, eyeball movements, and intercostal muscle suppression.
In the early 1900s, premedication was introduced. In 1937, Guedel published the clinical signs of ether anesthesia including smooth muscle tone, respiratory pattern, and ocular signs into four periods.
In 1942, the introduction of muscle relaxants. In 1954, Arturio extended Guedel's period I to 3 degrees with the name of grade 1 respectively, the patient did not lose consciousness and relieve pain; Grade 2 is a patient with total loss of consciousness and local pain relief, grade 3 is a patient with complete loss of consciousness and analgesia.
In 1987, Prys-Roberts defined anesthesia as a state in which the patient is not aware or recalls harmful stimuli during anesthesia. Loss of consciousness is a threshold, all-or-nothing rule.

There are 3 methods applied in determining anesthesia including:
Clinical observation EEG Measurement of anesthetic concentration

To determine the level of anesthesia, the patient is monitored for changes in the body's physiological response from the moment of superficial anesthesia to deep anesthesia. Arrange the reactions in successive phases corresponding to anesthesia. This technique is considered the simplest and easiest to perform.

During anesthesia, the patient is fitted with an electroencephalogram (EEG). By observing the indicators on the screen of the EEG meter, especially the bi-spectral index BIS, it is possible to assess the patient's level of awakening or coma. BIS runs from 0 - 99, BIS = 0, EEG is quiet, BIS = 99, the patient is awake, it is best that the patient should be maintained BIS = 40 to 60. This technique is quite complicated and expensive, so it is not widely used.

The patient's anesthesia is determined by checking the anesthetic concentration in the arterial blood or by the last breath exhaled. However, each patient with the same anesthetic concentration has different physiological responses. Therefore, this technique is complicated, difficult to define and time consuming, and is not widely applied.

The signs and duration of Guedel's anaesthesia are described as follows:
Stage I: Analgesia
The period of this sedation lasts from induction of anesthesia until the patient loses consciousness. Although it is called the analgesia, the patient still feels pain.
Stage II: Delirium
The sign to determine the level of anesthesia in stage II is that the patient begins with a state of excitement, struggling and ends when breathing becomes regular, loss of eyelid reflexes and pharynx. throat (vomiting state persists). Absolutely should not stimulate the patient during this period.
Stage III: Surgery
The surgical period is divided into 4 stages with 4 different levels of anesthesia:
Grade 1: Determined by observing dilated peripheral veins, vomiting reflex vomiting fades away. This phase lasts from the end of period II until the eyeball is in the middle of the eye.
Level 2: This stage lasts from when the eyeball stops moving to when the intercostal muscles stop working, the patient breathes in the chest. At grade 2, when the patient loses the reflex to constrict the larynx, the doctor begins to make an incision in the skin for surgery. As anesthesia deepens, muscle tone will continue to decrease. However, muscle tone can also be increased when there is a lack of oxygen, an excess of carbon dioxide.
3: The patient is rarely maintained at this level of anesthesia. Grade 3 is started from decreased intercostal muscle activity to complete loss of activity, the patient breathes by abdominal breathing.
4: At grade 4, the patient has complete paralysis of the intercostal muscles, spontaneous breathing stops and tracheal traction occurs due to the deep anesthesia.
Stage IV: Poisoning
This period starts from spontaneous apnea to circulatory collapse, all reflexes are lost. The patient should be resuscitated by reducing the concentration of anesthetic in the blood and lungs immediately.

Determining the level of anesthesia is an important job during anesthesia to ensure safety during surgery, as well as the life of the patient. Therefore, before performing surgical anesthesia for examination and treatment, patients should choose reputable medical facilities with a system of modern medical supplies.
Vinmec International General Hospital has applied anesthesia techniques in examination, diagnosis, and surgical treatment of many diseases. Before administering anesthesia on the patient, the medical team at Vinmec always perform the full procedure, the steps of pre-anesthesia examination, medical history,... During the surgery, monitoring can be done. integrated on modern ventilator anesthesia machine can assess the level of anesthesia in anesthesia practice. Therefore, most cases of surgical anesthesia at Vinmec minimize the unwanted reactions.
Thanks to modern facilities, a team of experienced and qualified medical professionals will bring the highest satisfaction to customers using services at Vinmec.
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