Artikel
Can we assess cerebrovascular autoregulation after head injury using brain tissue oxygen pressure reactivity?
Ist die Einschätzung der zerebrovaskulären Autoregulation nach SHT mittels Hirngewebssauerstoffdruckreaktivität möglich?
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
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Objective
The aim of this study was to investigate whether two newly developed indices of brain tissue oxygen (PtiO2) pressure reactivity, named ORx and bPtiO2, allow an estimation of the status of cerebrovascular autoregulation after head injury? This was accomplished by validating these new indices against an established parameter of autoregulation, the cerebrovascular pressure reactivity index (PRx).
Methods
In 27 patients continuous monitoring of mean arterial blood pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), and partial pressure of brain tissue oxygen (PtiO2) was performed for an average period of 6.5 days. ORx was calculated as a moving correlation coefficient between values of CPP and PtiO2. The bPtiO2 was calculated as a moving value of the slope of the linear regression function between CPP and PtiO2. PRx was calculated as a moving correlation coefficient between values for ICP and MAP. Outcome was assessed at six months after trauma (Glasgow Outcome Scale).
Results
ORx and bPtiO2 correlated significantly with PRx (r = 0.55 for ORx, r=0.53 for bPtiO2, p<0.01). PRx and ORx showed a significantly negative correlation to the monitored PtiO2 values (r=-0.42 for PRx, r=-0.41 for ORx, p<0.05) and outcome (r=-0.52 for PRx, r=-0.62 for ORx, p<0.01), whereas bPtiO2 did not. ICP and CPP showed no correlation to outcome.
Conclusions
ORx and, to a lesser extent, bPtiO2 correlated with the autoregulatory marker PRx. This indicates that these new indices offer additional information on the status of cerebrovascular autoregulation after head injury. The data also suggested that patients with impaired autoregulation are at increased risk for secondary cerebral hypoxia and worse outcome.