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Lack of correlation among intracerebral cytokines, intracranial pressure, and brain tissue oxygenation in patients with traumatic brain injury and diffuse lesions*

Objectives:To determine the evolution of cytokine patterns using microdialysis in patients with traumatic brain injury with diffuse lesions and to study the relationship between cytokines and intracranial pressure, brain tissue oxygenation and lesion type on the computed cranial tomography scan (patients with and without brain swelling). Design:Prospective and observational study. Setting:Third-level university hospital. Patients:Patients between 15 and 65 yrs with severe traumatic brain injury and a diffuse lesion requiring intracranial pressure and brain tissue oxygenation monitoring were eligible. Interventions:Microdialysis catheters with a high-cutoff membrane of 100 kDa were inserted. Results:Sixteen patients were included in the analysis. There was a substantial interindividual variability between cytokine values. The highest concentrations for the interleukin-1&bgr;, interleukin-6, and interleukin-8 were measured during the first 24 hrs followed by a gradual decline. The average concentration for interleukin-10 did not vary over time. This pattern is the most frequent in patients with traumatic brain injury with diffuse lesions. The intracranial pressure–cytokines correlation coefficients for the 16 patients varied substantially: interleukin-1&bgr;–intracranial pressure (−0.76 to 0.63); interleukin-6–intracranial pressure (−0.83 to 0.78); interleukin-8–intracranial pressure (−0.86 to 0.84); and interleukin-10–intracranial pressure (−0.36 to 0.65). The brain tissue oxygenation–cytokine correlation coefficients, like with intracranial pressure, also varied between patients: interleukin-1&bgr;–brain tissue oxygenation (−0.49 to 0.68), interleukin-6–brain tissue oxygenation (−0.99 to 0.84); interleukin-8–brain tissue oxygenation (−0.65 to 0.74); and interleukin-10–brain tissue oxygenation (−0.34 to 0.52). Similarly, we found no difference in the cytokine values inpatient microdialysis with and without swelling in the computed tomographic scan. Conclusions:No clear relationship was found between the temporal pattern of cytokines and the behavior of the intracranial pressure, brain tissue oxygenation, and the presence or absence of swelling in the computed tomography scan. This study demonstrates the feasibility of microdialysis in recovering cytokines for a prolonged time, although there may be some nonresolved methodologic problems with this technique when we try to study the inflammation during traumatic brain injury that could affect the results and make interpretation of microdialysis data prone to difficulties.