Elevated Intracranial Pressure, Low Cerebral Perfusion Pressure, and Impaired Brain Metabolism Correlate with Fatal Outcome After Severe Brain Injury^[*]

Abstract

Background New brain tissue monitoring techniques (tissue oxymetry, microdialysis) provide direct information about the state of brain oxygenation and brain metabolism in patients with severe traumatic brain injury (TBI). Despite this information being limited to a small region of the brain surrounding the probes, it could be associated with such global parameters as the clinical outcome.

Objective To study the predictive value of monitoring brain oxygenation and metabolism on clinical outcome in patients in the acute phase of severe TBI.

Methods An observational study of 20 patients with a severe TBI was undertaken, utilizing intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygenation, and brain metabolism monitoring. We correlated the clinical outcome of the patients with the following parameters: ICP, CPP, brain tissue oxymetry (PbtO₂), glucose and glycerol levels, and the lactate/pyruvate (LP) ratio. Further, we analyzed the relationship between ICP, CPP, PbtO₂, and the metabolism parameters.

Results We found a correlation of the mean ICP values (8.73 ± 1.18 in group A vs. 26.32 ± 5.01 mmHg in group B, p < 0.005), the mean CPP values (84.82 ± 2.02 in group A vs. 66.62 ± 4.64 mmHg, p < 0.005), the LP ratio (37.36 ± 3.44 vs. 199 ± 87.97, p < 0.05), and glycerol levels (62.07 ± 12.14 vs. 215 ± 46.52 μmol/l, p < 0.05) with the clinical outcome. High ICP correlated with both a high LP ratio (Spearman R = 0.61, p < 0.05), and elevated glycerol concentrations (Spearman R = 0.48, p < 0.05). A low CPP correlated with a high LP ratio (Spearman R = −0.57, p < 0.05), while a low PbtO₂ correlated with a high LP ratio (Spearman R = −0.49, p < 0.05).

Conclusions High ICP, low CPP, an elevated mean LP ratio, and high glycerol concentrations in the acute phase predict fatal outcome 6 months after TBI. Further, high ICP, low CPP, and low PbtO₂ correlate with impaired brain metabolism.

Keywords

head injury - multimodal monitoring - microdialysis - tissue oxymetry - outcome

• References

• 1 Flaada JT, Leibson CL, Mandrekar JN , et al. Relative risk of mortality after traumatic brain injury: a population-based study of the role of age and injury severity. J Neurotrauma 2007; 24: 435-445
• 2 Firsching RJ, Voellger B. Evidence-based indications for ICP recording after head injury. A review. Cen Eur Neurosurg 2010; 71: 134-137
• 3 De Georgia MA, Deogaonkar A. Multimodal monitoring in the neurological intensive care unit. The Neurologist 2005; 11: 45-54
• 4 Stahl N, Schalen W, Ungerstedt U , et al. Bedside biochemical monitoring of the penumbra zone surrounding an evacuated acute subdural haematoma. Acta Neurol Scand 2003; 108: 211-215
• 5 Clausen T, Alves OL, Reinert M , et al. Association between elevated brain tissue glycerol levels and poor outcome following severe traumatic brain injury. J Neurosurg 2005; 103: 233-238
• 6 Valadka AB, Gopinath SP, Contant CF , et al. Relationship of brain tissue PO₂ to outcome after severe head injury. Crit Care Med 1998; 26: 1576-1581
• 7 Li AL, Zhi DS, Wang Q , et al. Extracellular glycerol in patients with severe traumatic brain injury. Chin J Traumatol 2008; 11: 84-88
• 8 van den Brink WA, van Santbrink H, Avezaat CJ , et al. Monitoring brain oxygen tension in severe head injury: the Rotterdam experience. Acta Neurochir Suppl 1998; 71: 190-194
• 9 Zauner A, Doppenberg EM, Woodward JJ , et al. Continuous monitoring of cerebral substrate delivery and clearance: initial experience in 24 patients with severe acute brain injuries. Neurosurgery 1997; 41: 1082-1091 ; discussion 1091–1083
• 10 Meixensberger J, Jaeger M, Väth A , et al. Brain tissue oxygen guided treatment supplementing ICP/CPP therapy after traumatic brain injury. J Neurol Neurosurg Psychiatry 2003; 74: 760-764
• 11 Peerdeman SM, Girbes AR, Polderman KH , et al. Changes in cerebral interstitial glycerol concentration in head-injured patients; correlation with secondary events. Intensive Care Med 2003; 29: 1825-1828
• 12 Reinstrup P, Stahl N, Mellergard P , et al. Intracerebral microdialysis in clinical practice: baseline values for chemical markers during wakefulness, anesthesia, and neurosurgery. Neurosurgery 2000; 47: 701-709 ; discussion 709–710
• 13 Belli A, Sen J, Petzold A , et al. Metabolic failure precedes intracranial pressure rises in traumatic brain injury: a microdialysis study. Acta Neurochir (Wien) 2008; 150: 461-469 ; discussion 470
• 14 Alessandri B, Reinert M, Young HF , et al. Low extracellular (ECF) glucose affects the neurochemical profile in severe head-injured patients. Acta Neurochir Suppl 2000; 76: 425-430
• 15 Van den Berghe G, Wilmer A, Hermans G , et al. Intensive insulin therapy in the medical ICU. N Engl J Med 2006; 354: 449-461
• 16 Oddo M, Schmidt JM, Carrera E , et al. Impact of tight glycemic control on cerebral glucose metabolism after severe brain injury: a microdialysis study. Crit Care Med 2008; 36: 3233-3238
• 17 Bratton SL, Chestnut RM, Ghajar J , et al. Guidelines for the management of severe traumatic brain injury. I. Blood pressure and oxygenation. J Neurotrauma 2007; 24 (Suppl 1) S7-S13