Cerebral state index during anaesthetic induction: a comparative study with propofol or nitrous oxide.
BACKGROUND
Confidently predicting the depth of anaesthesia for the individual patient and independently of drug(s) type using EEG-based monitors has proven difficult. This open, randomized, explorative study of day surgical patients evaluates the ability of the Cerebral State Monitor (Danmeter AB, Odense, Denmark) of anaesthetic depth to identify loss of response (LOR) using either propofol or N(2)0 for induction.


METHODS
In this open, randomized study, day surgical patients (n=10 in each group) were studied using the Cerebral State Index Monitor. After baseline measurements, induction to LOR was achieved with either repeated 30-mg boluses of propofol every second minute or with N(2)0 (after premedication 5 min before with 30 mg propofol) increased every other minute in 15% increments (max. 75%). Sedation level was evaluated every other minute using the Observer's Assessment of Alertness/Sedation scale.


RESULTS
Baseline values were 91 (82-98) and 94 (82-100) for N(2)0 and propofol patients, respectively. During induction CSI decreased with increasing sedation in patients given propofol (P<0.001) but not in patients given nitrous oxide. Median value at LOR was 56 (40-76) and 95 (87-100) for the propofol and nitrous oxide group of patients, respectively.


CONCLUSIONS
The Cerebral State Index(trade mark) behaves as other depth of anaesthesia monitors with a progressive decrease during propofol induction but loss of consciousness with N(2)0 results in no change in CSI.
Anderson
R E
RE
Department of Cardiothoracic Anaesthetics and Intensive Care, Karolinska Hospital, Stockholm, Sweden.
Barr
G
G
Jakobsson
J G
JG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000556:Ambulatory Surgical Procedures; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009609:Nitrous Oxide; D015742:Propofol; D011446:Prospective Studies; D012018:Reflex / Q000187:drug effects
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D009609:Nitrous Oxide; D015742:Propofol