High extracellular potassium and its correlates after severe head injury: relationship to high intracranial pressure.

M. Reinert, A. Khaldi, A. Zauner, E. Doppenberg, S. Choi, Ross Bullock

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Disturbed ionic and neurotransmitter homeostasis are now recognized to be probably the most important mechanisms contributing to the development of secondary brain swelling after traumatic brian injury (TBI). Evidence obtained from animal models indicates that posttraumatic neuronal excitation via excitatory amino acids leads to an increase in extracellular potassium, probably due to ion channel activation. The purpose of this study was therefore to measure dialysate potassium in severely head injured patients and to correlate these results with intracranial pressure (ICP), outcome, and also with the levels of dialysate glutamate, lactate, and cerebral blood flow (CBF) so as to determine the role of ischemia in this posttraumatic ionic dysfunction. Eighty-five patients with severe TBI (Glasgow Coma Scale score < 8) were treated according to an intensive ICP management-focused protocol. All patients underwent intracerebral microdialyis. Dialysate potassium levels were analyzed by flame photometry, as were dialysate glutamate and dialysate lactate levels, which were measured using high-performance liquid chromatography and an enzyme-linked amperometric method in 72 and 84 patients respectively. Cerebral blood flow studies (stable Xenon--computerized tomography scanning) were performed in 59 patients. In approximately 20% of the patients, potassium values were increased (dialysate potassium > 1.8 mmol). Mean dialysate potassium (> 2 mmol) was associated with ICP above 30 mm Hg and fatal outcome. Dialysate potassium correlated positively with dialysate glutamate (p < 0.0001) and lactate levels (p < 0.0001). Dialysate potassium was significantly inversely correlated with reduced CBF (p = 0.019). Dialysate potassium was increased after TBI in 20% of measurements. High levels of dialysate potassium were associated with increased ICP and poor outcome. The simultaneous increase of potassium, together with dialysate glutamate and lactate, supports the hypothesis that glutamate induces ionic flux and consequently increases ICP due to astrocytic swelling. Reduced CBF was also significantly correlated with increased levels of dialysate potassium. This may be due to either cell swelling or altered potassium reactivity in cerebral blood vessels after trauma.

Original languageEnglish
JournalNeurosurgical focus [electronic resource].
Volume8
Issue number1
StatePublished - Dec 1 2000
Externally publishedYes

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Dialysis Solutions
Intracranial Pressure
Craniocerebral Trauma
Potassium
Cerebrovascular Circulation
Glutamic Acid
Lactic Acid
Wounds and Injuries
Glasgow Coma Scale
Excitatory Amino Acids
Intracranial Hypertension
Fatal Outcome
Brain Edema
Ion Channels
Neurotransmitter Agents
Blood Vessels
Homeostasis
Ischemia
Animal Models
Head

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High extracellular potassium and its correlates after severe head injury : relationship to high intracranial pressure. / Reinert, M.; Khaldi, A.; Zauner, A.; Doppenberg, E.; Choi, S.; Bullock, Ross.

In: Neurosurgical focus [electronic resource]., Vol. 8, No. 1, 01.12.2000.

Research output: Contribution to journalArticle

Reinert, M. ; Khaldi, A. ; Zauner, A. ; Doppenberg, E. ; Choi, S. ; Bullock, Ross. / High extracellular potassium and its correlates after severe head injury : relationship to high intracranial pressure. In: Neurosurgical focus [electronic resource]. 2000 ; Vol. 8, No. 1.
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