IngentaConnect Online assessment of brain tissue oxygen autoregulation in trauma...

Authors: Soehle M.¹; Jaeger M.; Meixensberger J.

Source: Neurological Research, Volume 25, Number 4, June 2003 , pp. 411-417(7)

Abstract:

Monitoring of brain tissue oxygenation (p_tiO₂) enables early diagnosis of secondary cerebral ischemia and may guide a cerebral perfusion pressure (CPP) orientated therapy. The purpose of our study was to explain the concept of p_tiO₂-autoregulation, defined as the ability of the brain to maintain p_tiO despite changes in CPP, and to show the different states of p_tiO₂-autoregulation we found. Microcatheters to assess p_tiO₂ 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 p_tiO₂ and CPP based on a data buffer consisting of 12 h. Depending on the linear regression slope (b_ptiO₂ = Delta

p_tiO₂/

CPP), we defined the state of p_ti₂O-autoregulation as present (0

b_ptiO2

1/6), moderate (1/6 < b_ptiO2

1/3), impaired (b_ptiO2 > 1/3) or inverse (b_ptiO2 < 0). When p_tiO₂-autoregulation is present, an elevation in CPP is ineffective to raise p_tiO₂. In contrast, an increase in CPP elevates p_tiO₂ more pronounced in impaired than in moderate p_tiO₂-autoregulation, but decreases p_tiO₂ in inverse p_tiO₂-autoregulation. We conclude that online assessment of p_tiO₂-autoregulation gives valuable information on which patient will benefit from an increase in CPP and which CPP should be achieved to do so.

Keywords: BRAIN TISSUE OXYGENATION; CEREBRAL AUTOREGULATION; TRAUMATIC BRAIN INJURY; SUBARACHNOID HEMORRHAGE; CEREBRAL PERFUSION PRESSURE; MULTIMODAL CEREBRAL MONITORING

Document Type: Research article

DOI: 10.1179/016164103101201580

Affiliations: 1: Department of Neurosurgery, University of Leipzig, Germany

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Online assessment of brain tissue oxygen autoregulation in traumatic brain injury and subarachnoid hemorrhage