Abstract
Introduction: Neurointensive care of traumatic brain injury (TBI) patients is currently based on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targeted protocols. There are reasons to believe that knowledge of brain tissue oxygenation (BtipO2) would add information with the potential of improving patient outcome. The aim of this study was to examine BtipO2 and cerebral metabolism using the Neurovent-PTO probe and cerebral microdialysis (MD) in TBI patients.Methods: Twenty-three severe TBI patients with monitoring of physiological parameters, ICP, CPP, BtipO2, and MD for biomarkers of energy metabolism (glucose, lactate, and pyruvate) and cellular distress (glutamate, glycerol) were included. Patients were grouped according to injury type (focal/diffuse) and placement of the Neurovent-PTO probe and MD catheter (injured/non-injured hemisphere).Results: We observed different patterns in BtipO2 and MD biomarkers in diffuse and focal injury where placement of the probe also influenced the results (ipsilateral/contralateral). In all groups, despite fairly normal levels of ICP and CPP, increased MD levels of glutamate, glycerol, or the L/P ratio were observed at BtipO2 <5 mmHg, indicating increased vulnerability of the brain at this level.Conclusion: Monitoring of BtipO2 adds important information in addition to traditional ICP and CPP surveillance. Because of the different metabolic responses to very low BtipO2 in the individual patient groups we submit that brain tissue oximetry is a complementary tool rather than an alternative to MD monitoring.
Highlights
Neurointensive care of traumatic brain injury (TBI) patients is currently based on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targeted protocols
Despite fairly normal levels of ICP and CPP, increased MD levels of glutamate, glycerol, or the L/P ratio were observed at BtipO2
FOCAL BRAIN INJURY AND PROBE PLACEMENT ON THE CONTRALATERAL SIDE ICP, CPP, and BtipO2 During monitoring ICP mean values ranged between 12 and 17 mmHg and CPP was in the range 70–90 mmHg at BtipO2 levels of ≥10 mmHg
Summary
Neurointensive care of traumatic brain injury (TBI) patients is currently based on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targeted protocols. The aim of this study was to examine BtipO2 and cerebral metabolism using the Neurovent-PTO probe and cerebral microdialysis (MD) in TBI patients. The management of TBI patients is largely based on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) targeted treatment protocols in order to prevent secondary brain injury and to improve patient outcome [3,4,5,6,7]. Multi-modality monitoring of brain tissue oxygenation (BtipO2) and cerebral metabolism [e.g., with microdialysis (MD)], provides information for early detection of brain ischemia and could possibly be used to avoid secondary ischemic brain injury [15]. The secondary objective was to determine if the response pattern differed depending on type of injury and probe localization
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