Cerebral perfusion pressure and risk of brain hypoxia in severe head injury: a prospective observational study.

INTRODUCTION: Higher and lower cerebral perfusion pressure (CPP) thresholds have been proposed to improve brain tissue oxygen pressure (PtiO2) and outcome. We study the distribution of hypoxic PtiO2 samples at different CPP thresholds, using prospective multimodality monitoring in patients with severe traumatic brain injury. METHODS: This is a prospective observational study of 22 severely head injured patients admitted to a neurosurgical critical care unit from whom multimodality data was collected during standard management directed at improving intracranial pressure, CPP and PtiO2. Local PtiO2 was continuously measured in uninjured areas and snapshot samples were collected hourly and analyzed in relation to simultaneous CPP. Other variables that influence tissue oxygen availability, mainly arterial oxygen saturation, end tidal carbon dioxide, body temperature and effective hemoglobin, were also monitored to keep them stable in order to avoid non-ischemic hypoxia. RESULTS: Our main results indicate that half of PtiO2 samples were at risk of hypoxia (defined by a PtiO2 equal to or less than 15 mmHg) when CPP was below 60 mmHg, and that this percentage decreased to 25% and 10% when CPP was between 60 and 70 mmHg and above 70 mmHg, respectively (p < 0.01). CONCLUSION: Our study indicates that the risk of brain tissue hypoxia in severely head injured patients could be really high when CPP is below the normally recommended threshold of 60 mmHg, is still elevated when CPP is slightly over it, but decreases at CPP values above it.

Acute community-acquired bacterial meningitis in adults admitted to the intensive care unit: clinical manifestations, management and prognostic factors.

OBJECTIVE: To study the clinical features, management and prognostic factors associated with adverse clinical outcome in a series of patients with acute community-acquired bacterial meningitis admitted to the intensive care unit (ICU). DESIGN AND SETTING: Descriptive, prospective study at two ICUs of a university hospital over a 6-year period. PATIENTS: Sixty-four episodes in 62 adults with acute community-acquired bacterial meningitis admitted to the ICU. RESULTS: Most of the patients (95.3%) were admitted to the ICU presenting with altered mental status (the median value of Glasgow Coma Scale (GCS) was 11). Overall mortality rate was 10.9% (7 patients) and 11 (17.1%) developed adverse clinical outcome (death or severe neurologic deficit). The features associated with adverse clinical outcome were: age over 50 years, seizures or focal neurologic signs at admission, a GCS score of 10 or less and an APACHE II score more than 13 at admission to the ICU. Only the severity of the disease determined according to the APACHE II scale was independently associated with adverse clinical outcome after a multivariate analysis was performed (adjusted odds ratio =8.74; 95% CI =1.70-44.77; p=0.009). All patients were empirically treated with third-generation cephalosporins and dexamethasone was used in 40 cases (62.5%). Ten patients (15.6%) received mannitol, nine of them after a transcranial Doppler sonography recording had been performed. CONCLUSIONS: In adult patients with acute community-acquired bacterial meningitis admitted to the ICU, the overall severity of the disease within 24 h of admission may be the major indicator of adverse in-hospital clinical outcome.

Impact of ventilator-associated pneumonia in patients with severe head injury.

BACKGROUND: The impact of ventilator-associated pneumonia (VAP) on outcome seems to vary depending on the critically ill patients we analyze. Our objective, therefore, has been to evaluate the influence of VAP on the mortality and morbidity in patients with severe head injury (Glasgow Coma Scale score