Quantitative cerebral blood flow and metabolism determination in the first 48 hours after severe head injury with a new dynamic spect device

Objective: To determine cerebral blood flow (CBF) and metabolism in the acute phase after severe head injury by a new dynamic SPECT device using ¹³³Xenon and to evaluate a possible role of CBF and metabolism in the determination of prognosis. Design: Prospective study. Setting: General intensive care unit in a universitary teaching hospital. Subjects: 23 severely head injured patients having CT scan and CBF determination, intracranial pressure (ICP) and jugular bulb oxygen saturation monitoring in the first 48 hours. Measurements and main results: CBF varied from 18.0 to 60.0 ml/100,g/min. No correlation was found between early CBF and severity of trauma evaluated with the Glasgow Coma Score (GCS) (F = 2.151, p = 0.142) and between CBF and prognosis at 6 months evaluated with Glasgow outcome score (GOS) (F = 0.491, p = 0.622; r(s)= 0.251, p = 0.246). CMRO₂ was depressed in relation to the severity of injury, specifically ranging from 0.9 ± 0.5 ml/ 100 g/min in patients with GCS 3 to 1.7 ± 0.8 ml/100 g/min in patients with GCS 6-7. In no patient with a CMRO₂ less than 0.8 ml/100 g/min was a good outcome observed. A significant correlation was found between GCS and GOS (r(s) = 0.699, p = 0.0002), between CMRO₂ and GOS (F = 4.303, p = 0.031; r(s) = 0.525, p = 0.013) and between AJDO₂ and GOS (F= 3.602, p = 0.046; r(s) = 0.491, p = 0.017). Fronto-occipital ratio (F/O) of CBF distribution lion was significantly lower than normal values (χ²,18.658, p = 0.001) but did not correlate either with prognosis χ² = 1.626, p = 0.443) or with severity (χ² = 1.913, p = 0.384). Conclusions: CBF in the first 48 hours after trauma varies within a large range of values and is not correlated with severity and prognosis. Clinical evaluation with GCS and CMRO₂ are much more reliable indicators of severity of head trauma and have a significant role in the determination of prognosis. F/O ration is significantly altered from normal values confirming 'post-traumatic hypofrontalism' but does not correlate with severity and prognosis.