Extracellular Brain pH and Outcome following Severe Traumatic Brain Injury.

The ability to measure brain tissue chemistry has led to valuable information regarding pathophysiological changes in patients with traumatic brain injury (TBI). Over the last few years, the focus has been on monitoring changes in brain tissue oxygen to determine thresholds of ischemia that affect outcome. However, the variability of this measurement suggests that it may not be a robust method. We have therefore investigated the relationship of brain tissue pH (pH(b)) and outcome in patients with TBI. We retrospectively analyzed prospectively collected data of 38 patients admitted to the Neurosciences Critical Care Unit with TBI between 1998 and 2003, and who had a multiparameter tissue gas sensor inserted into the brain. All patients were managed using an evidence-based protocol targeting CPP > 70 mm Hg. Physiological variables were averaged over 4 min and analyzed using a generalized least squares random effects model to determine the temporal profile of pH(b) and its association with outcome. Median (IQR) minimum pH(b) was 7.00 (6.89, 7.08), median (IQR) maximum pH(b) was 7.25 (7.18, 7.33), and median (IQR) patient averaged pH(b) was 7.13 (7.07, 7.17). pH(b) was significantly lower in those who did not survive their hospital stay compared to those that survived. In addition, those with unfavorable neurological outcome had lower pH(b) values than those with favorable neurological outcome. pH(b) differentiated between survivors and non-survivors. Measurement of pH(b) may be a useful indicator of outcome in patients with TBI.

Non-neurological organ dysfunction in neurocritical care.

PURPOSE: To determine the incidence of non-neurological organ dysfunction in patients with severe neurological injury. MATERIALS AND METHODS: Modified daily SOFA (mSOFA) scores were retrospectively calculated for 55 consecutive patients with severe head injury or subarachnoid hemorrhage. mSOFA was defined as the sum of the 5 non-neurological component SOFA scores, maximum mSOFA as the sum of the most abnormal non-neurological SOFA component scores and delta mSOFA as the difference between maximum mSOFA and admission mSOFA. Organ failure was defined as a SOFA component score > or =3. RESULTS: Median (IQR) admission, maximum and delta mSOFA scores were 4 (3-6), 8 (6-9), and 2 (1-5), respectively. Respiratory and cardiac failure developed in 80% and 82% of patients, respectively. No patient developed renal or hepatic failure. Three patients developed hematological failure. There was no difference between survivors and nonsurvivors with respect to admission mSOFA (P =.45), maximum mSOFA (P =.54), or delta mSOFA (P =.19). There was no difference between those patients with favorable or unfavorable neurological outcome with respect to admission mSOFA (P =.24), maximum mSOFA (P =.84), or delta mSOFA (P =.20). CONCLUSIONS: Cardiopulmonary failure, as defined by SOFA, is common in intensive care unit patients with severe head injury and subarachnoid hemorrhage. In contrast to other intensive care unit patient populations, the mortality of patients with closed head injury or subarachnoid hemorrhage was not related to the severity of organ dysfunction on admission or its development during the intensive care unit stay.