Influence of acute normovolemic hemodilution on bispectral index monitoring - A clinical study

Abstract

Background: Recently with cognitive function tests was shown that ANH, a blood procurement technique, results in an increased reaction time and memory alterations. This significant impairment of cognitive function can be detected with EEG and consequently with BIS, an EEG derived parameter. Methods: We explored whether ANH has an effect on BIS monitoring before induction and during maintenance of propofol TCI anesthesia and whether ANH has an influence on the required propofol dose. The 45 unmedicated patients were randomly allocated in one of three groups: the ANH with oxygen insufflation, the ANH with air insufflation and the control group. BIS was recorded during the whole process. Results: In the ANH groups a significant BIS decline after ANH could be observed but returns to baseline value by breathing 100% oxygen before induction of anesthesia. During maintenance of narcosis no significant differences between the ANH and the control group could be detected. Furthermore in the ANH group a lower dose of propofol was necessary for achieving LOC what was followed by significantly higher BIS values. Conclusion: The briefly decreased BIS value after ANH could be returned to baseline by breathing oxygen. The transient enhancement of propofol hypnotic potency through ANH during induction of anesthesia cant be observed during maintenance of porpofol narcosis.

Date of Award	2011
Original language	English
Awarding Institution	Medical University Graz
Supervisor	Helfried Metzler (Supervisor)