Simultaneous measurement of cortical potassium, calcium, and magnesium levels measured in head injured patients using microdialysis with ion chromatography.

Potassium, calcium and magnesium were measured in 3717 microdialysate samples in 43 patients with head injury experiencing refractory increased ICP, episodes of jugular venous oxygen desaturation and brain death. Cation analysis was performed with 'ion chromatography'. Potassium levels remained stable until severe physiological deterioration occurred, whereupon they increased 100-400%, usually associated with release of amino-acids including glutamate, aspartate, and taurine into the extracellular space. The magnesium and calcium levels remained unchanged, regardless of the severity of physiological deterioration.