Brain Ischemia Detected by Tissue-PO2 Measurement and the Lactate-Oxygen Index in Head Injury
The aim of the study was to find out whether there is a correlation between the tissue-pO2 (ti-pO2) measurement and the lactate-oxygen index (mLOI). Both methods are to be considered as methods to detect brain ischemia. We studied 7 patients after severe
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© Springer-Verlag 1998
Brain Ischemia Detected by Tissue-PO z Measurement and the Lactate-Oxygen Index in Head Injury M. Holzschuh, C. Metz', C. Woertgen, R. D. Rothorl, and A. Brawanski Department of Neurosurgery and I Department of Anesthesiology, University of Regensburg. Regensburg. Federal Republic of Germany
Summary
Material and Methods
The aim of the study was to find out whether there is a correlation between the tissue-pOl (ti-pO~) measurement and the lactateoxygen index (mLO!). Both methods are to be considered as methods to detect brain ischemia. We studied 7 patients after severe head injury (GCS < 8) with a jugular bulb catheter and a tissue pOl probe. Possible ischemia was defined with ti-pO~ below lOmmHg and mLO! above 0.08. 67 pairs of ti-pO~ and corresponding mLOI were found. In 5 cases out of the 7 cases with a ti-p02 below 10 we found a pathological mLOI above 0.08. In 11 cases with pathological mLO] values. however, we found only 6 cases of decreased ti-p02' The absolute values did not correlate. The sensitivity to predict normal values is above 85% with both methods. The specifity to predict ischemia is low «72%). The reason is the fact. that ti-p02 is a local method in contrast to the mLOI values. In cases of diffuse brain injury without major contusions there should be a correlation between ti-pO~ and the mLOI.
We studied 7 patients after severe head injury with an initial Glasgow-Coma-Scale below 8. All patients were treated in the intensive care unit. They were treated with sedation, mechanically ventilated and they received routinely two jugular bulb catheters and a clark-type electrode (L1COX, GMS, Germany). The L1COX probe was placed in the frontal white matter. Every six hours blood was drawn from both jugular bulb catheters and the mLOI (mLOI = A VOL/CEO) was calculated. Ti-p02 data were stored every 15 seconds on hard disc. We calculated the average of the ti-p02 data that were sampled 30 minutes before the time of the blood drawing for the calculation of the mLOI. For comparison of the data we used the mlOI value of the hemisphere where the ti-p02 probe was inserted. According to the literature possible ischemia was defined with ti-pO~ below 10 mmHg and mlO! above 0.08.
Keywords: Jugular bulb catheters; lactate-oxygen index; secondary brain ischemia; tissue-PO~.
Results
Introduction It is generally accepted that the initial clinical status of the patient after trauma, the age and the type of structural brain damage are important factors of outcome prediction after severe head injury [4]. Additionally, to these primary factors there is increasing evidence that secondary brain ischemia after severe head injury is one of the major causes of poor outcome after brain trauma [1,5,6]. The modified lactate-oxygen index (mLOI)(2) and the brain tissue pOz (ti-pOz) [3,7] have been proposed as indicators of ischemic brain tissue. The aim of the study was to find out whether there is a correlation between these two methods of brain ischemia detection.
We found 67 pairs of ti-pOz and corr
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