Objective: The study presented evaluated the first clinical use of a new multiparameter catheter measuring intracranial pressure (ICP), partial pressure of brain tissue oxygen (ptiO2), and brain temperature (TBr) (Neurovent PTO). To assess the validity of measured ptiO2 a second probe, which represents the current golden standard of ptiO2 measurement, was implanted (Licox system).
Methods: Thirty patients with indicated invasive measurement of ICP under intensive care unit conditions were included. Using a double lumen bolt, ptiO2 was measured simultaneously with Licox and Neurovent PTO. Ex vivo tests on both probes were conducted independently by the manufacturer of the Neurovent PTO (Raumedic AG, Germany).
Results: The average of individual mean ptiO2 measurements showed no relevant differences between the Licox (19.5+/-7.1) and Neurovent multiparameter probe (21.7+/-9.5). Twenty-eight Licox probes out of 30 showed proper functioning over the desired monitoring period. Raumedic multiparameter probes displayed a higher malfunction/handling error frequency (2 device errors, 11 handling errors). A comparison of the ptiO2 data between the Licox and Raumedic systems according to Bland and Altman was possible in 18 out of 30 patients and showed acceptable results (mean difference -1.24 mm Hg; limits of agreement: -25.1 to +22.6 mm Hg). A total of 95.2% of 96,083 recordings was within the calculated limits of agreement. Ex vivo tests of the probes after explantation revealed stable ICP and TBr function of the Raumedic probe. Precision of Zero ptiO2 did not differ between the probes, whereas precision of the 150 mm Hg ptiO2 was greater in the Raumedic probes.
Conclusions: Combining 3 different neuromonitoring functions in 1 probe might ease monitoring by making a second (ptiO2) probe unnecessary. Interpretation of our data is limited by several factors: (1) monocentric study; (2) reduced mechanical probe stability, handling difficulties with the double lumen bolt; (3) design changes to improve mechanical stability will require further study; (4) conflict of interest with Raumedic because of its support for the study. The conclusion drawn from our study is that the new multiparameter probe evaluated does measure ICP, TBr, and ptiO2. But all the initial data given in this paper have to be interpreted cautiously. A new study will be necessary when the mechanical stability of the new probe has been improved.