Evaluation of Significance of Bispectral Index As a Monitor of Depth of Anesthesia
HAYTHAM SAEED HANAFI;
Abstract
"Awareness" under general anesthesia can finally be considered as the "invisible scar of surgery". This unexpected and undesirable patient wakefulness under general anesthesia has been considered as a source of pain and torture tomany individuals after surgery.
The incidenceof awareness in general surgical population has been estimated to be0.1 to 0.2%.A higher incidence is reported for obstetric general anesthesia0.4%and can increase up to 1.0 to 1.5% in high-risk cardiac surgical patients and trauma cases.
Risk factors for awareness include:
• Patient related factors (such as unstable hemodynamics, drug addicts and alcoholics).
• Surgical factors (certain types of surgeries such as trauma, obstetric and high risk cardiac surgery) which requires caution in general anesthetic drugs.
• Anesthesia related factors related to unbalancedanesthetic technique.
• Malfunctioning anesthetic equipments especially that responsible for delivering anesthetic gases or vapors lead to insufficient amount of the anesthetic to ensure patient unconsciousness.
• Doctor related factors such as negligence, unchecking of the anesthesia machine to detect any errors in vaporizes and ventilators or unattending the patient throughout the operation to detect early the clinical signs of awareness and adjust the concentrations of anesthetic drugs.
Patients undergoing CS under general anesthesia are at high risk of awareness. This is largely due to the use of low concentrations of volatile agents and the complete avoidance of opioid analgesia prior to delivery of the neonate. Also due to decrease in inhalational anesthetic concentration after delivery for fear of uterine atony.
Emerging evidence has therefore aroused that intraoperative monitoring of "depth of anesthesia" can significantly decrease the risk of awareness especially in high risk patients.
The BIS index is the first approved and reliable monitor that enables assessment of the hypnotic component of anesthesia. The BIS index is a processed EEG parameter calculated from several features of the cortical EEG index. This index uses a dimensionless number scaled from 100 (the awake state) to 0 (deep coma). BIS values of (40 to 60) reflect adequate hypnotic effects and have been established as the proper value for surgical anesthesia.
Other indices similar to BIS index such as the Narcotrend index, the patient state index and the SNAP index also hold a promise for accurate assessment of anesthetic depth. Other monitors also incorporated in DoA monitoring are the auditory evoked potential monitors which is incorporated in the A-line monitor which represent a promising parameter for monitoring DoA.
The aim of the present work To evaluate the significance of bispectral index as a monitor of depth of anesthesia by comparing the bispectral analysis monitor score and stress hormones level and hemodynamic readings at pre-determined intervals throughout the whole surgical procedure.So, if it beneficial we will recommend to widen its use to decrease the incidence of awareness during anesthesia and if not, we will go on searching for other methods to fulfill this target.
The incidenceof awareness in general surgical population has been estimated to be0.1 to 0.2%.A higher incidence is reported for obstetric general anesthesia0.4%and can increase up to 1.0 to 1.5% in high-risk cardiac surgical patients and trauma cases.
Risk factors for awareness include:
• Patient related factors (such as unstable hemodynamics, drug addicts and alcoholics).
• Surgical factors (certain types of surgeries such as trauma, obstetric and high risk cardiac surgery) which requires caution in general anesthetic drugs.
• Anesthesia related factors related to unbalancedanesthetic technique.
• Malfunctioning anesthetic equipments especially that responsible for delivering anesthetic gases or vapors lead to insufficient amount of the anesthetic to ensure patient unconsciousness.
• Doctor related factors such as negligence, unchecking of the anesthesia machine to detect any errors in vaporizes and ventilators or unattending the patient throughout the operation to detect early the clinical signs of awareness and adjust the concentrations of anesthetic drugs.
Patients undergoing CS under general anesthesia are at high risk of awareness. This is largely due to the use of low concentrations of volatile agents and the complete avoidance of opioid analgesia prior to delivery of the neonate. Also due to decrease in inhalational anesthetic concentration after delivery for fear of uterine atony.
Emerging evidence has therefore aroused that intraoperative monitoring of "depth of anesthesia" can significantly decrease the risk of awareness especially in high risk patients.
The BIS index is the first approved and reliable monitor that enables assessment of the hypnotic component of anesthesia. The BIS index is a processed EEG parameter calculated from several features of the cortical EEG index. This index uses a dimensionless number scaled from 100 (the awake state) to 0 (deep coma). BIS values of (40 to 60) reflect adequate hypnotic effects and have been established as the proper value for surgical anesthesia.
Other indices similar to BIS index such as the Narcotrend index, the patient state index and the SNAP index also hold a promise for accurate assessment of anesthetic depth. Other monitors also incorporated in DoA monitoring are the auditory evoked potential monitors which is incorporated in the A-line monitor which represent a promising parameter for monitoring DoA.
The aim of the present work To evaluate the significance of bispectral index as a monitor of depth of anesthesia by comparing the bispectral analysis monitor score and stress hormones level and hemodynamic readings at pre-determined intervals throughout the whole surgical procedure.So, if it beneficial we will recommend to widen its use to decrease the incidence of awareness during anesthesia and if not, we will go on searching for other methods to fulfill this target.
Other data
| Title | Evaluation of Significance of Bispectral Index As a Monitor of Depth of Anesthesia | Other Titles | Evaluation of Significance of Bispectral Index As a Monitor of Depth of Anesthesia | Authors | HAYTHAM SAEED HANAFI | Issue Date | 2015 |
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