Auditory evoked potential monitoring with the AAITM-index during spinal surgery: decreased desflurane consumption.
BACKGROUND
The auditory evoked potential (AEP) is sensitive to the depth of anesthesia. The A-line monitor is a novel device that processes the amplitude and latency of the AEP during the mid-latency time window to provide a simple numerical index, the AAItrade mark-index. The hypothesis of the present study was that titration of anesthetic depth (desflurane) by means of the AAItrade mark-index could decrease the consumption of the main anesthetic and shorten emergence times.


METHODS
Thirty ASA I-II patients scheduled for elective open spine surgery under general anesthesia were randomly allocated to two groups. Group I (n=15), the main anesthetic, desflurane, was titrated with a target AAItrade mark-index of 20+/-5. Group II (n=15), desflurane was titrated according to routine clinical signs, including heart rate, blood pressure, sweating and tears. No fixed MAC-multiple was sought. The primary study variable was desflurane consumption; and secondary study variables were time to extubation and orientation.


RESULTS
All patients had an uncomplicated course and no patients showed signs of awareness or had any recall postoperatively. AAItrade mark-index guidance reduced desflurane consumption by 29% and improved emergence. Time until extubation and orientation and ability to state name and date of birth was significantly shortened among AAItrade mark-index titrated patients.


CONCLUSIONS
Titrating depth of desflurane anesthesia using AAItrade mark-index guidance decreased main anesthetic consumption and improved emergence during spine surgery.
Department of Orthopaedics, Sabbatsberg Hospital, Stockholm, Sweden.
H
H
Määttänen
R
R
Anderson
J
J
Uusijärvi
J
J
Jakobsson
D000368:Aged; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D000077335:Desflurane; D005072:Evoked Potentials, Auditory; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage* / Q000031:analogs & derivatives; D016343:Monitoring, Intraoperative; D013131:Spine / Q000601:surgery*
D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane