Online assessment of brain tissue oxygen autoregulation in traumatic brain injury and subarachnoid hemorrhage.
Monitoring of brain tissue oxygenation (ptiO2) 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 ptiO2-autoregulation, defined as the ability of the brain to maintain ptiO2 despite changes in CPP, and to show the different states of ptiO2-autoregulation we found. 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 h. Depending on the linear regression slope (bptiO2 = delta ptiO2/delta CPP), we defined the state of ptiO2-autoregulation as present (0 < or = bptiO2 < or = 1/6), moderate (1/6 < bptiO2 < or = 1/3), impaired (bptiO2 > 1/3) or inverse (bptiO2 < 0). When ptiO2-autoregulation is present, 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- autoregulation, but decreases ptiO2 in inverse ptiO2-autoregulation. We conclude that online assessment of ptiO2-autoregulation gives valuable information on which patient will benefit from an increase in CPP and which CPP should be achieved to do so.
Soehle
Martin
M
Department of Neurosurgery, University of Leipzig, Johannisallee 34, 04103 Leipzig, Germany.
Jaeger
Matthias
M
Meixensberger
Jürgen
J
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001921:Brain / Q000378:metabolism*; D001929:Brain Edema / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism; D001930:Brain Injuries / Q000150:complications / Q000378:metabolism*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D002534:Hypoxia, Brain / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000378:metabolism*; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000378:metabolism*
D010100:Oxygen