RESUMO
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.
Assuntos
Traumatismos Craniocerebrais/complicações , Traumatismos Craniocerebrais/fisiopatologia , Hipóxia Encefálica/etiologia , Hipóxia Encefálica/fisiopatologia , Telencéfalo/irrigação sanguínea , Adulto , Pressão Sanguínea , Traumatismos Craniocerebrais/metabolismo , Cuidados Críticos/métodos , Estado Terminal , Feminino , Humanos , Hipóxia Encefálica/metabolismo , Masculino , Oxigênio/metabolismo , Estudos Prospectivos , Valores de Referência , Medição de Risco/métodos , Fatores de Risco , Telencéfalo/metabolismoRESUMO
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
