The cause and incidence of secondary insults in severely head-injured adults and children.

The cause and incidence of reductions in cerebral perfusion pressure, and rises in intracranial pressure have been examined in a series of patients with severe head injury defined as an initial Glasgow Coma Sum of less than or equal to 8. Two-hundred-and-seven adults (aged over 16 years) and 84 children admitted to Newcastle General Hospital, who had intracranial pressure monitoring as part of their routine management, were studied. Intracranial pressure (ICP), arterial pressure and cerebral perfusion pressure (CPP) were sampled and recorded every 2 min. Patients' CT findings were classified into distinct groups using the method described by Marshall. Secondary insults were defined using the Edinburgh University Secondary Insult Grades (EUSIG) and the incidence and cause (raised ICP, reduced CPP or a combination of the two) was established. Outcome was assessed at 6 months using the Glasgow Outcome Scale. In the majority of adults with head injury it is the combination of reduced arterial pressure and raised ICP that contributes to the reduction in cerebral perfusion pressure. This was not the case for Diffuse Injury Type I. In children similar characteristics were found across each of the CT classifications. The vast majority of falls in CPP down to 60 mmHg were caused by reduced arterial pressure. Reductions below 50 mmHg were almost always due to a combination of both reduced arterial pressure and raised ICP. The results in adults were similar, but not identical, to those of the paediatric cases. Diffuse Injury Type I stood out from all the other categories as the only one where reductions in perfusion pressure were almost exclusively due to reductions in arterial pressure and not to increases in ICP. The management of these patients should ensure the adequacy of perfusion pressure by maintaining arterial pressure at a satisfactory level. These results suggest that vigilant monitoring of both intracranial pressure and arterial pressure is required to lower the incidence of secondary insults.