Linear correlation between stable intracranial pressure decrease and regional cerebral oxygenation improvement following mannitol administration in severe acute head injury patients.
OBJECTIVES: We investigated the relationship between stable decrease in intracranial pressure (ICP) following mannitol administration and variations in regional oxygenation (PtiO2) in severe traumatic brain injured (STBI) patients. METHODS: Fourteen STBI patients (Glasgow Coma Scale score < or = 8) admitted to the neurointensive care unit during a 12-month period were studied. Multiparameter data, including parenchymal tissue oxygen (PtiO2) and carbon dioxide tension, cerebral perfusion pressure, mean arterial pressure; temperature, pH and pressure reactivity index were measured. Point values from 53 mannitol administrations were extracted every five seconds and divided into five consecutive 30-minute epochs. Mean values and trends were identified. Postadministration epoch with maximum decrease in ICP was selected along with the means of the corresponding variables. These data were compared with baseline to derive the delta values. Mean deltaICP was then compared with deltaPtiO2 in each patient using linear correlation. FINDINGS: In patients with ICP0 > 20 mmHg (group A), PtiO2 increased in 69.6% of samples, whereas in group B (ICP0 < 20 mmHg), PtiO2 increased in only 50% of the samples. There was a significant negative correlation between mean deltaICP and deltaPtiO2 in both groups; Group A: r = -0.79 (P = 0.01); Group B: r = -0.92 (P = 0.01). CONCLUSIONS: There is a strong negative correlation between stable decrease in ICP following mannitol administration and improvement in regional oxygenation around the peri-contusional area. The data suggest a potentially favourable interaction between mannitol therapy and cerebral internal milieu in STBI patients.