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October 22, 2005
9:00:00 AM - 11:00:00 AM
Hall C4
Quality of Recovery after AEP-Guided Anesthesia. Results of a Randomized Trial
Matthew T. Chan, F.A.N.Z.C.A., Tony Gin, M.D., Bassanio Law, F.A.N.Z.C.A., K.K. Liu, F.A.N.Z.C.A.
Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, Hong Kong
Background: Monitoring of anesthetic depth has been shown to reduce recovery times. However, it is unclear whether such monitoring technique can improve patient outcome. The objective of this study is to evaluate the impact of auditory evoked potential (AEP) monitoring on the rate and quality of recovery.

Methods: After obtaining ethics committee approval and written informed consent, 1,068 patients scheduled for elective non-cardiac surgery were randomly assigned to receive either AEP-guided anesthesia or routine care. Patients were also randomized to receive either target controlled propofol infusion or sevoflurane anesthesia. In the AEP group, anesthesia was adjusted to maintain an A-Line ARX index (AAI, Danmeter, Odense, Demark) between 15-25 during surgery. In the routine care group, anesthesia was adjusted according to traditional clinical signs. Quality of Recovery was measured regularly by a validated QoR scale.1 Recovery times and perioperative complications were recorded. Health related quality of life was also measured by the short-form health survey (SF-36) one month after surgery. Changes in QoR scores were analyzed by a generalized linear model. Recovery times and incidence of complications were compared among groups using Kruskal Wallis tests and logistic regression model, respectively.

Results: The average (±SD) AAI values during maintenance period of anesthesia were significantly lower in the control group (9±7) compared with the AEP group (20±11, P<0.001). The end-tidal sevoflurane and targeted plasma propofol concentration were reduced with AEP monitoring by 29% and 16%, respectively. This was associated with a decrease in the incidence of nausea and vomiting (48% vs 20%, P=0.001) or other complications (including hemodynamic, respiratory or infection, 36% vs 16%, P=0.002) in the AEP group compared with controls. After surgery, patients receiving AEP monitoring consistently rated their quality of recovery higher than the controls (Figure 1). Emergence from anesthesia in the AEP group was also faster than the controls and patients were discharged home earlier (6.9±5.2 vs 9.1±8.1 days, P=0.01). One month after surgery, the global SF-36 scores were higher in the AEP group (447±138) compared with the controls (440±129), P=0.02. Choice of anesthetic agent did not affect recovery profiles.

Conclusions: AEP monitoring improves anesthetic titration, leading to an improved recovery profile after surgery.

Reference: 1. Anesth Analg 1999;88:83-90.[figure1]

Anesthesiology 2005; 103: A48
Figure 1