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Unconscious learning during surgery with propofol anaesthesia.
C Deeprose1, J Andrade, S Varma
1Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TP, UK. c.deeprose@shef.ac.uk
British Journal of Anaesthesia
|January 15, 2004
Summary
Learning during anesthesia may occur during surgical stimulation, not before. This implicit memory formation during anesthesia suggests surgical stimuli facilitate learning, independent of anesthetic depth.
Area of Science:
- Anesthesiology
- Cognitive Neuroscience
- Neuroscience
Background:
- Learning during anesthesia is documented, but conditions promoting it are unclear.
- This study tested if learning occurs during, not before, surgical stimulation.
Purpose of the Study:
- To determine if surgical stimulation influences learning during propofol anesthesia.
- To investigate the timing of learning relative to surgical stimuli.
Main Methods:
- 64 patients received auditory word stimuli during propofol anesthesia, either before or during surgery.
- Memory was assessed post-anesthesia using word stem completion and recognition tests.
- Anesthetic depth was monitored using Bispectral Index (BIS).
Main Results:
- Patients receiving stimuli during surgery showed significant implicit memory (P<0.02).
- No explicit memory or awareness was detected in either group.
- Anesthetic depth (BIS) and vital signs were comparable, but propofol infusion and ventilation were higher during stimulation.
Conclusions:
- Learning during anesthesia is more likely during surgical stimulation than before, at similar anesthetic depths.
- Surgical stimulation may facilitate learning during anesthesia independently of anesthetic depth.