الفهرس 
IntroductionOnly 14 pages are availabe for public view
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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 to many
individuals after surgery.
The incidence of awareness in general surgical
population has been estimated to be 0.1 to 0.2%. A higher
incidence is reported for obstetric general anesthesia 0.4% 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 unbalanced anesthetic
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.