Continuous monitoring of PbrO2 in patients with severe head injury
The first Chapter is an introduction to neurotraumatology. The incidence of severe head injury, and its financial burden to society is described. General information is provided on the currently used monitoring modalities in patients with severe head injury. Finally a description is given of the polarographic monitoring method for measuring oxygen tension in brain tissue (PbrO2) used in our studies. The study questions are specified focussing on clinical applicability of PbrO2 measurements in TBI and interpretation of findings. In Chapter 2 preliminary experience with brain tissue PO2 (PbrO2) monitoring in a group of 22 patients with a severe head injury is described. PbrO2 was measured with a polarographic microcatheter. For introduction of the catheter a specially devised intracranial bolt was used. Measurements started as soon as possible after the injury and the study protocol specified an observation period of a maximum of 120 hours post trauma. The rationale for this time period was that during the initial period after trauma low Cerebral Blood Flow (CBF) values have been reported with Xe CT studies, and that vasospasm mostly occurs before day 5 after injury. Both potential ischemic phenomena are covered by the observation period chosen. During the observation period two provocation tests were included in the study protocol performed on a dayly basis. Firstly, an O2 provocation test, by increasing the fraction of inspired oxygen stepwise to 1.0, and secondly a carbon dioxide reactivity test performed by increasing the respiratory minute volume of the patient by 20%. The observation period was preliminary terminated by early death or if clinical improvement of the patient occurred to an extent that ICP monitoring was no longer considered necessary. PbrO2 monitoring was started on average 7.0 hours after trauma with a mean duration of 74.3 hours. The chapter provides an extensive description of all phenomena observed. No complications were seen related to the PbrO2 catheter. The catheters showed a zero display error of 1.2 ± 0.8 mmHg and a sensitivity drift of 9.7 ± 5.3% after the measurement period. The first approach to analyse the PbrO2 value was to average all PO2 values according to the time after injury. Using this method of analysis we observed low average values during the initial 24 hours after injury, increasing toward a peak value during the second 24 hours reaching a plateau value after 36-48 hours after injury. Beyond this time period mean PbrO2 showed no further changes.
|Keywords||hersenbeschadiging, monitoring, neurologie|
|Promotor||Avezaat, C.J.J. (Cees)|
|Sponsor||Medtronic Prof.dr. A.W. Unterberg Prof.dr. J. Klein Prof.dr. C. de Zeeuw Dr. A.I.R. Maas (co-promotor)|
van Santbrink, H.. (2004, March 10). Continuous monitoring of PbrO2 in patients with severe head injury. Retrieved from http://hdl.handle.net/1765/7261