Intracerebral microdialysis in clinical practice: baseline values for chemical markers during wakefulness, anesthesia, and neurosurgery.
OBJECTIVE
The study was undertaken to measure baseline values for chemical markers in human subjects during wakefulness, anesthesia, and neurosurgery, using intracerebral microdialysis.


METHODS
Microdialysis catheters were inserted into normal posterior frontal cerebral cortex in nine patients who were undergoing surgery to treat benign lesions of the posterior fossa. The perfusion rate was 1.0 microl/min during anesthesia/neurosurgery and the early postoperative course and 0.3 microl/min during the later course. Bedside biochemical analyses of glucose, pyruvate, lactate, glycerol, glutamate, and urea were performed before, during, and after neurosurgery. After the bedside analyses, all samples were frozen for subsequent high-performance liquid chromatographic analyses of amino acids.


RESULTS
The following baseline values were obtained during wakefulness (perfusion rate, 0.3 microl/min): glucose, 1.7+/-0.9 mmol/L; lactate, 2.9+/-0.9 mmol/L; pyruvate, 166+/-47 micromol/L; lactate/pyruvate ratio, 23+/-4; glycerol, 82+/-44 micromol/L; glutamate, 16+/-16 mmol/L; urea, 4.4+/-1.7 mmol/L. Marked increases in the levels of all chemical markers were observed at the beginning and end of anesthesia/surgery.


CONCLUSIONS
The study provides human baseline levels for biochemical markers that can presently be measured at the bedside during neurointensive care. In addition, some changes that occurred under varying physiological conditions are described.
Reinstrup
P
P
Department of Anesthesiology, Lund University Hospital, Sweden.
Ståhl
N
N
Mellergård
P
P
Uski
T
T
Ungerstedt
U
U
Nordström
C H
CH
D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D000768:Anesthesia, General; D001786:Blood Glucose / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D018698:Glutamic Acid / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008577:Meningeal Neoplasms / Q000503:physiopathology / Q000601:surgery*; D008579:Meningioma / Q000503:physiopathology / Q000601:surgery*; D017551:Microdialysis / Q000379:methods*; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009464:Neuroma, Acoustic / Q000503:physiopathology / Q000601:surgery*; D019289:Pyruvic Acid / Q000378:metabolism; D012016:Reference Values; D014508:Urea / Q000378:metabolism; D014851:Wakefulness / Q000502:physiology*
D000596:Amino Acids; D001786:Blood Glucose; D019344:Lactic Acid; D018698:Glutamic Acid; D019289:Pyruvic Acid; D014508:Urea; D005990:Glycerol