How to monitor anesthesia by electroencephalogram?

The article was professionally approved by Doctor Nguyen Xuan Tinh - Anesthesiologist - Resuscitation at the Department of General Surgery - Vinmec Phu Quoc International General Hospital

Waking up during surgery is a dangerous problem that can lead to neurological dysfunctions of patients after surgery. Therefore, a number of machines to help monitor brain function to assess the depth of anesthesia were born, especially the electroencephalogram (EEG)-based anesthesia monitoring method.

The patient's level of anesthesia will be assessed during both the induction and maintenance phases of anesthesia, specifically as follows:

The doctor will assess the patient's level of sedation and loss of eyelid reflexes based on the MOAAS score of 5 levels:
OASS 5: the patient is fully awake, responding immediately when calling his name in a normal voice OASS 4: patient responds slowly or vaguely to name calling in normal voice OASS 3: patient responds only to loud name calling or repeated repetition OASS 2: patient responds only to loud name calling and gentle shaking OASS 1: Patient responds only to loud name calling and vigorous shaking

This is the time when the patient's anesthesia will be assessed based on the changes in blood pressure, heart rate, sweating, lacrimation (PRST scale) and patient movement. However, if anesthesia is used with muscle relaxants or the patient is in hemodynamic instability, anemia, hemorrhagic shock, etc., the assessment of anesthesia based on the above criteria is no longer accurate. again. In addition, the anesthetic dose for a healthy young patient compared with an elderly, frail, debilitated or comorbid patient is also completely different and it is difficult to achieve the theoretical standard dosage.

Digital EEG Anesthesia monitoring method is a method of using the computer inside the anesthesia monitor to analyze data from the patient's EEG during surgery through the processing of waves. electroencephalogram of the frontal lobe. The patient's brain waves will be digitized into natural numbers from 100-0 respectively from fully awake to very deep sleep. The indices are converted as follows:
BIS from 100-91: awakened patients without pre-anesthesia BIS from 80 to 70: patients with loss of consciousness BIS less than 60: anesthesia status (low memory risk) BIS from 60-40: anesthesia is sufficiently deep BIS less than 40: deep anesthesia BIS less than 20: anesthesia is too deep Accordingly, anesthetics are ideally adjusted so that the BIS index is between 40-60 (the period of anesthesia maintenance). ) during surgery, reduce the dose of anesthetic during the period of anesthesia release and recovery. Monitoring of anesthesia by electroencephalogram will help reduce the cost of anesthetic use, time to recover and reduce the disturbance of hemodynamic, awakening, and recall during anesthesia of the patient.

In fact, there are studies that suggest that BIS and other anesthesia depth monitoring systems are not currently considered the gold standard for preventing patient awakening during surgery or accurately assessing the depth of anesthesia. anesthesia in special patients. In addition, the BIS index is also affected by the choice of anesthetic, for example, a patient with a BIS score of 60 receiving a combination of anesthetics may have a deeper anesthetic than a patient with the same score but causing more pain. anesthesia in combination with other drugs. The BIS also varied greatly from the Glasgow scale in emergency room patients.
Anesthesia monitoring method by EEG is a method of using a computer inside the anesthesia monitor to analyze data from the EEG during surgery through the processing of the brain's electrical waves. frontal lobe.