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Impaired explicit memory after recovery from propofol/sufentanil anaesthesia is related to changes in the midlatency
I Rundshagen1, K Schnabel, J Schulte am Esch
1Department of Anaesthesiology, University Hospital Charité, Campus Charité Mitte, Schumannstrasse 20/21, D-10117 Berlin, Germany.
Background:
Midlatency auditory evoked responses (MLAER) can distinguish different stages of anaesthesia. We studied MLAER during emergence from propofol/sufentanil anaesthesia in relation to recovery of explicit memory.
Methods:
MLAER were recorded in 29 healthy patients before and during anaesthesia and during emergence until the patients opened their eyes spontaneously. After a structured interview the next day, patients were classified into those with and without explicit memory of the recovery period. Latencies Na, Pa and Nb and the peak-to-peak amplitudes NaPa and PaNb were compared between the groups by multivariate analysis of variance. Results are mean (SD).
Results:
At eye opening (37 (12) min after the end of anaesthesia) the latency Nb (47 (5) compared with 41 (5) ms; P < 0.001) was prolonged and the amplitude PaNb (1.3 (0.8) compared with I (0.5) ms; P = 0.012) was greater than the baseline value, respectively. The Nb latency was significantly shorter in patients with explicit memory (49 (2) ms compared with 45 (I); P = 0.041).
Conclusions:
Large intra- and inter-individual variability in the MLAER values limited their ability to predict memory responses in individual patients during emergence from propofol/sufentanil anaesthesia.
Insights
Midlatency auditory evoked responses (MLAER) showed variability during anesthesia emergence. While MLAER could not reliably predict individual memory recovery, changes in Nb latency were noted.
Area of Science:
- Neuroscience
- Anesthesiology
- Auditory Evoked Potentials
Background:
- Midlatency auditory evoked responses (MLAER) are known to differentiate anesthesia stages.
- Investigating MLAER during emergence from propofol/sufentanil anesthesia in relation to explicit memory recovery.
Purpose of the Study:
- To assess the utility of MLAER in predicting explicit memory during emergence from propofol/sufentanil anesthesia.
- To analyze MLAER parameters (Na, Pa, Nb latencies; NaPa, PaNb amplitudes) in relation to memory recall.
Main Methods:
- MLAER recorded in 29 patients pre-anesthesia, during anesthesia, and emergence until eye-opening.
- Patients classified post-anesthesia into groups with and without explicit memory via interview.
- Multivariate analysis of variance used to compare MLAER between groups.
Main Results:
- At eye-opening, Nb latency was prolonged (47 vs. 41 ms) and PaNb amplitude increased (1.3 vs. 1.0 ms) compared to baseline.
- Nb latency was significantly shorter in patients with explicit memory (49 vs. 45 ms).
Conclusions:
- Significant intra- and inter-individual variability in MLAER values was observed.
- This variability limited the predictive ability of MLAER for individual memory responses during emergence.
- MLAER may not be a reliable sole predictor of memory during this anesthetic recovery phase.