Article
Relationship of hemodynamic and metabolic parameters after traumatic brain injury
Zusammenhang von hämodynamischen und metabolischen Parametern nach Schädel-Hirn-Trauma
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Published: | April 11, 2007 |
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Objective: Monitoring of brain tissue oxygenation (ptiO2) and cerebral blood flow (CBF) is performed to detect impending secondary brain damage after traumatic brain injury (TBI) and critical thresholds have been derived from clinical data previously. The objective of this study was to correlate hemodynamic and metabolic parameters and to evaluate whether the known thresholds are associated with metabolic changes.
Methods: Multiparametric neuromonitoring including ptiO2 (Licox), thermal diffusion CBF (Hemedex) and microdialysis (CMA) was performed continuously in 6 patients for up to 8 days after severe TBI. To correlate the metabolite concentrations with the other parameters, hourly values were calculated. Episodes of hypoxia and hypoperfusion were analyzed for metabolic changes and correlations were assessed using Pearsons correlation coefficient.
Results: Cerebral hypoxia (ptiO2<10mmHg) was associated with increased glutamate concentrations (10.3±9.1 vs. 1.5±1.9µM; p<0.05), an increase in the lactate/pyruvate ratio (56.8±31.3 vs. 22.4±11.5; p<0.05), reduced CBF (14.6±7.6 vs. 23.7±11.4ml/100g/min), reduced CPP and increased ICP. Hypoperfusion (CBF<15ml/100g/min) was associated with increased glutamate levels (2.6±4.0 vs. 1.3±1.5µM, p<0.05), reduced glucose levels, increased lactate/pyruvate ratio, increased ICP and reduced ptiO2. There was a correlation of CBF with concentrations of glucose, glutamate and pyruvate.
Conclusions: Episodes of cerebral hypoxia or hypoperfusion as indicated by neuromonitoring techniques are associated with potentially detrimental metabolic alterations. Thus, neuromonitoring-guided therapy may prove to be beneficial in the management of TBI.