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Absence of implicit and explicit memory during propofol/remifentanil anaesthesia.
P Y Lequeux1, C E Velghe-Lenelle, F Cantraine
1Erasmus Hospital, Department of Anaesthesiology, ULB, Brussels, Belgium.
European Journal of Anaesthesiology
|May 28, 2005
Summary
High doses of remifentanil combined with low-dose propofol anesthesia did not result in implicit or explicit memory in patients. This anesthetic technique, commonly used, was evaluated for its impact on postoperative memory recall.
Area of Science:
- Anesthesiology
- Neuroscience
- Pharmacology
Background:
- High-dose opioid and low-dose hypnotic anesthesia, utilizing remifentanil, is increasingly common.
- This anesthetic approach may potentially increase the incidence of implicit memory.
Purpose of the Study:
- To investigate the incidence of implicit and explicit memory in patients receiving remifentanil and propofol anesthesia.
- To assess memory formation at low propofol concentrations associated with loss of consciousness.
Main Methods:
- Ten patients received target-controlled infusions of remifentanil and propofol.
- Propofol infusion was gradually increased to loss of consciousness, with word lists presented during anesthesia.
- Bispectral Index (BIS) was monitored, and postoperative memory tests were conducted.
Main Results:
- Loss of consciousness was achieved at a mean propofol plasma concentration of 1.3 ± 0.4 μg/mL.
- No implicit or explicit memory was detected in any of the three postoperative memory tests.
- The median BIS value during word presentation was 93 (range 80-98).
Conclusions:
- In young, healthy patients (ASA I/II), anesthesia with high-dose remifentanil and low-dose propofol did not induce explicit or implicit memory.
- The findings suggest that memory formation is unlikely at propofol concentrations causing loss of consciousness with high BIS values under this anesthetic regimen.