gms | German Medical Science

62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

07. - 11. Mai 2011, Hamburg

Measuring cerebrovascular autoregulation using the oxygen reactivity index (ORX) – does the probe type matter?

Meeting Abstract

  • J. Dengler - Klinik für Neurochirurgie, Charité - Universitätsmedizin Berlin
  • C. Frenzel - Klinik für Neurochirurgie, Charité - Universitätsmedizin Berlin
  • P. Vajkoczy - Klinik für Neurochirurgie, Charité - Universitätsmedizin Berlin
  • P. Horn - Klinik für Neurochirurgie, Charité - Universitätsmedizin Berlin
  • S. Wolf - Klinik für Neurochirurgie, Charité - Universitätsmedizin Berlin

Deutsche Gesellschaft für Neurochirurgie. Polnische Gesellschaft für Neurochirurgen. 62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH). Hamburg, 07.-11.05.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. DocMO.06.07

DOI: 10.3205/11dgnc035, URN: urn:nbn:de:0183-11dgnc0350

Veröffentlicht: 28. April 2011

© 2011 Dengler et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: The newly proposed oxygen reactivity index (ORX) has been shown to be linked to neurological outcome after traumatic brain injury and subarachnoid haemorrhage. Currently, the main debate focuses on whether ORX correlates with the established pressure reactivity index (PRX). Furthermore, there still is no consensus on which exact cerebral tissue oxygenation (ptiO2) measurement probe should be applied to calculate ORX. We therefore conducted a prospective trial to compare ORX values from two different ptiO2 probes (Licox (LX), CC1.SB, Integra Neuroscience, France and Raumedic (NV), Neurovent-PTO, Raumedic, Germany) to each other and to other indices measuring AR.

Methods: 12 patients (7 males, mean age 57 ± 8 years) with an indication for intraparenchymal ptiO2 measurement during intensive care treatment were included. Each patient received a Licox and a Raumedic probe side by side into the same cerebrovascular region. ORX values, which by definition range from –1 to +1, from both probes were calculated continuously using online ptiO2 and cerebral perfusion pressure (CPP). They were compared to each other and to cerebral blood flow (CBF), measured by an intraparenchymal thermodiffusion probe (Hemedex, Cambridge, USA), CPP, PRX and the recently suggested flow reactivity index (FRX). Correlations were quantified using Pearson’s correlation as well as the method proposed by Bland and Altman with correction for repeated measurements.

Results: Mean monitoring time per patient was 7.2 ± 2.5 days. ORX values from both probes showed a negligible mean difference of 0.05, but wide limits of agreement (95% CI) ranging from –0.56 to +0.67. No significant correlation was found when each probe’s ORX values were compared to the PRX. Neither did both probes’ ORX values did not correlate with CBF, CPP or FRX.

Conclusions: This study shows that ORX strongly depends on which specific ptiO2 probe is used for its calculation. None of the probes proved to be superior when ORX was compared to the established PRX. Both probes’ ORX values failed to display correlation not only to PRX but also to CBF, CPP and FRX. Our data therefore support the view that different studies on the topic of ORX can only be compared if corresponding ptiO2 probes are applied and that ORX cannot easily be correlated to PRX, CBF and CPP.