On severe traumatic brain injury : aspects of an intra cranial pressure-targeted therapy based on the Lund concept
Abstract: Severe Traumatic Brain Injury (sTBI) is a major cause of mortality and morbidity. At the Department of Neurosurgery Umeå University Hospital subjects with sTBI are treated with an intracranial pressure (ICP) guided therapy based on physiological principles, aiming to optimise the microcirculation of the brain so avoiding secondary brain injuries. The investigations in this thesis are unique in the sense that all patients with sTBI were treated according to the guidelines of an ICP targeted therapy based on the “Lund concept”.As the treatment is based on normalisation of the ICP, the accuracy and reliability of the measuring device is of outmost importance. Therefore the accuracy, drift, and complications related to the measuring device was prospectively studied (n=128). The drift was 0,9 ± 0,2 mmHg during a mean of 7,2 ± 0,4 days and the accuracy high. No clinical significant complications were noted.In 1997 uni- or bilateral decompressive hemi-craniectomy (DC) was introduced into the treatment guidelines. The effect of DC on the ICP and outcome was retrospectively analysed for subjects with sTBI treated 1998-2001. In the subjects who underwent DC the ICP was 36,4 mmHg immediately before and 12,6 mmHg immediately after the DC. The ICP then levelled out at just above 20 mmHg. The ICP was significant lower during the 72 hours following DC. The outcome did not differ between subjects who had undergone DC or not.Subclinical electroencephalographic seizures and status epilepticus have been reported to be common in subjects treated for traumatic brain injury (TBI). This can negatively influence the outcome giving rise to secondary brain injuries. The occurrence of seizures in subjects treated for TBI using continuous EEG monitoring was therefore prospectively studied. During 7334 hours of EEG recording in 47 patients no electroencephalographic seizures were observed.Theoretically, and based on animal studies, prostacyclin (PGI2) can improve the microcirculation of the brain, decreasing the risk for secondary ischaemic brain injury. PGI2 was introduced to the treatment in a prospective randomised double blinded study (epoprostenol 0,5 ng/kg/min). The effect of PGI1 pkt was analysed using the lactate/pyruvate ratio (L/P) measured by cerebral microdialysis in order to study the energy metabolism in the brain. The outcome was measured as Glasgow Outcome Scale (GOS) at 3 months follow-up. Forty-eight subjects were included. The L/P was pathological high during the first day, thereafter decreasing. There was no significant difference in L/P or outcome between the treated and non-treated group. At 3 months the mortality was 12,5% (95,8% was discharged alive from the ICU), and favourable outcome (GOS 4-5) was 52%.In the same study the brain injury biomarkers S-100B and NSE were followed twice a day for five days to evaluate brain injury and investigate the possible use of these biomarkers for outcome prediction. Initially the biomarkers were elevated to pathological levels which decreased over time. The biomarkers were significant elevated in subjects with Glasgow Coma Scale 3 (GCS) and GOS 1 compared with subjects with GCS 4-8 and GOS 2–5, respectively. A correlation to outcome was found but this correlation could not be used to predict clinical outcome.It is concluded that the ICP measurements are valid and the treatment protocol is a safe and solid protocol, yielding among the best reported results in the world, in regard to favourable outcome as well as in regard to mortality. Epoprostenol in the given dose was not shown to have any effects on the microdialysis parameters nor the clinical outcome. In sTBI L/P and brain injury biomarkers can not be used to predict the final outcome.
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