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Does nitrous oxide antagonize isoflurane-induced suppression of learning?
B S Chortkoff1, H L Bennett, E I Eger
1Department of Anesthesia, University of California, San Francisco 94143-0648.
Anesthesiology
|October 1, 1993
Summary
Nitrous oxide and isoflurane show slight antagonism, meaning they slightly counteract each other
Area of Science:
- Anesthesiology
- Neuroscience
- Pharmacology
Background:
- Nitrous oxide (N2O) and isoflurane have different potencies in suppressing consciousness and learning.
- N2O's potential to increase sympathetic activity may influence its interaction with isoflurane.
- This study investigated if N2O antagonizes isoflurane's learning suppression.
Purpose of the Study:
- To test the hypothesis that nitrous oxide antagonizes isoflurane's suppression of learning.
- To evaluate the combined effects of subanesthetic concentrations of N2O and isoflurane on cognitive function.
Main Methods:
- 24 healthy male volunteers received combinations of isoflurane and N2O at three subanesthetic concentrations.
- Learning was assessed using trivia questions and a category-example task.
- Response to verbal commands was also measured (MAC-awake).
Main Results:
- The combination of isoflurane and N2O showed antagonism for suppressing response to verbal commands (MAC-awake was higher than predicted).
- Antagonism was also observed for learning suppression, with significantly more learning occurring than predicted.
- No learning was detected in the category or behavior tasks at high concentrations.
Conclusions:
- Results support antagonism between nitrous oxide and isoflurane.
- The observed antagonism between these anesthetics is small in magnitude.