EARLY ISCHEMIA AFTER SEVERE HEAD-INJURY PRELIMINARY-RESULTS IN PATIENTS WITH DIFFUSE BRAIN INJURIES

Ischaemic brain lesions still have a high prevalence in fatally head i njured patients and are the single most important cause of secondary b rain damage. The present study was undertaken to explore the acute pha se of severely head injured patients in order to detect early ischaemi a using Robertson's approach of estimating cerebral blood flow (CBF) f rom calculated arterio-jugular differences of oxygen (AVDO2), lactates (AVDL), and the lactate-oxygen index (LOI). Twenty-eight cases with s evere head injury were included (Glasgow Coma Scale Score below or equ al to 8). All patients but one had a non-missile head injury. All the patients had a diffuse brain injury according to the admission CT scan . ICP measured at the time of admission was below 20 mmHg in 17 cases (61%). All patients were evaluated with the ischaemia score (IS) devis ed in our center to evaluate risk factors for developing ischaemia. Me an time from injury to the first AVDO2/AVDL study was 23.9 +/- 9.9 hou rs. According to Robertson's criteria, 13 patients (46%) had a calcula ted LOI (- AVDL/AVDO2) value above or equal to 0.08 and therefore an i schaemia/infarction pattern in the first 24 hours after the accident. Of the 15 patients without the ischaemia/infarction pattern, in three cases the CBF was below the metabolic demands and therefore in a situa tion of compensated hypoperfusion. No patient in our series had hypera emia. Comparing different variables in ischaemic and non-ischaemic pat ients, only arterial haemoglobin and ischaemia score (IS) was signific antly different in both groups. The ischaemia score had mean of 4.3 +/ - 1.7 in the ischaemic group and 2.7 +/- 1.4 in non-ischaemic patients (p = 0.01). It is concluded that ischaemia is highly prevalent in the early period after severe head injury. Factors potentially responsibl e of early ischaemia are discussed.