Artikel
Online assessment of brain tissue oxygen pressure reactivity in traumatic brain injury and subarachnoid hemorrhage
Online-Erfassung der zerebralen Gewebesauerstoff-Druckreaktivität bei Schädel-Hirn-Trauma und Subarachnoidalblutung
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Autoren
Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
Monitoring of brain tissue oxygenation (ptiO2) enables early diagnosis of secondary cerebral ischemia and may guide a cerebral perfusion pressure (CPP)-orientated therapy. The aim of our study was to explain the concept of ptiO2 pressure reactivity, defined as the ability of the brain to maintain ptiO2 despite changes in CPP, and to show the different states of ptiO2 pressure reactivity we found.
Methods
Microcatheters to assess ptiO2 and intracranial pressure were implanted into cerebral 'tissue at risk' of patients suffering from traumatic brain injury or subarachnoid hemorrhage. By using a multimodal neuromonitoring setup and in-house built software we assessed and displayed online the relationship between ptiO2 and CPP based on a data buffer consisting of 12 hours.
Results
Depending on the linear regression slope (bptiO2=Δ ptiO2/Δ CPP), we defined the state of ptiO2 pressure reactivity as preserved (0?bptiO2?1/6), moderate (1/6<bptiO2?1/3) or inverse (bptiO2<0). In preserved ptiO2 pressure reactivity, an elevation in CPP is ineffective to raise ptiO2. In contrast, an increase in CPP elevates ptiO2 more pronounced in impaired than in moderate ptiO2 pressure reactivity, but decreases ptiO2 in inverse ptiO2 pressure reactivity.
Conclusions
Online assessment of ptiO2 pressure reactivity gives valuable information on which patient will benefit from an increase in CPP and which CPP should be achieved to do so.