[Auditory evoked potentials index for monitoring the depth of desflurane anesthesia in the elderly].
OBJECTIVE
To observe the changes of auditory evoked potentials (AEP) index, mean arterial blood pressure (MAP) and heart rate (HR) undergoing desflurane anesthesia in the elderly and to evaluate the use of AEP index for monitoring the depth of desflurane anesthesia in the elderly.


METHODS
Forty patients classified as ASA physical status I-III undergoing general anesthesia were divided into 2 groups with 20 patients in each group: Group elderly (> or =65 years) and Group youth (18-55 years). Anesthesia was induced with propofol and vecuronium. After the endotracheal intubation, the lungs were ventilated with desflurane in oxygen. End-tidal concentration of desflurane was maintained at 0.6 MAC, 1.0 MAC and 1.3 MAC for 20 min, respectively. The changes of MAP, HR and AEP index were recorded simultaneously.


RESULTS
During the anesthesia of desflurane, MAP decreased significantly compared with those at preanesthesia in both groups. And HR decreased significantly compared with those at preanesthesia only in Group elderly (P < 0.05). The changes of MAP and HR had no statistical difference with increasing end-tidal desflurane concentration from 0.6 MAC to 1.3 MAC in both groups (P > 0.05). During the anesthesia of desflurane, AEP index decreased significantly compared with those at preanesthesia in both groups (P < 0.05). In the periods of increasing concentration of desflurane, AEP index decreased gradually. In Group elderly, AEP index decreased significantly 1.0 MAC and 1.3 MAC of desflurane compared with those of 0.6 MAC (P < 0.05). In Group youth, the changes of AEP index had no statistical difference with increasing end-tidal desflurane concentration from 0. 6 MAC to 1.3 MAC (P > 0.05). At the same concentration of desflurane, AEP index in the Group elderly were less than those in Group youth (P < 0.05). AEP index correlated with the end-tidal desflurane concentration significantly. The coefficient of product-moment correlation (r) were -0.983 and -0.980, respectively in Group elderly and Group youth (P < 0.05).


CONCLUSIONS
AEP index correlates well with the end-tidal desflurane concentration which is valuable for monitoring the depth of desflurane anesthesia in the elderly. AEP index can show the different depth of anesthesia at the same end-tidal desflurane concentration between the elderly and youth.
Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, China. caijin713@yahoo.com.cn
Jin
J
Cai
Qu-lian
QL
Guo
Zhao-hui
ZH
Tang
Wang-yuan
WY
Zhou
D000368:Aged; D018685:Anesthetics, Inhalation; D000077335:Desflurane; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000031:analogs & derivatives*; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*
D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane