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

SummaryObjective To determine cerebral blood flow (CBF) and metabolism in the acute phase after severe head injury by a new dynamic SPECT device using¹³³Xenon and to evaluate a possible role of CBF and metabolism in the determination of prognosis.Design Prospective studySetting General intensive care unit in a universitary teaching hospitalSubjects 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 was significantly lower than normal values (²=18.658, p = 0.001) but did not correlate either with prognosis (² = 1.626, p = 0.443) or with severity (² = 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.