Importance of Metabolic Monitoring Systems as an Early Prognostic Indicator in Severe Head Injured Patients

Summary

We have analyzed and evaluated what is the best metabolic monitoring system to determine the prognosis for maintenance of neurological function in severe head injured patients. Acute subdural hematoma (ASDH) was recognized in fifteen of 22 patients and cerebral contusion in seven in this series. Intracranial pressure (ICP), jugular venous pH and jugular bulb venous oxygen saturation (SJO₂) were continuously monitored as soon as possible following stabilization. The measurement of cerebral blood flow (CBF) was carried out using a stable Xenon-computerized tomography (Xe-CT). After measuring CBF, 3% carbon dioxide (CO₂) loading was conducted to determine CO₂ responses (ΔCBF/ACO₂). In patients who died (D), jugular venous pH showed evidence of acidosis (6.3–7.2) with ACBF/ACO₂ < 1 and cerebral metabolic rate of oxygen (CMRO₂) < 1.21 within several hours of the trauma. On the other hand, arterial pH was shown to be within the normal range. In vegetative state (VS) and severe disability (SD) patients, jugular venous pH was shown to be within normal range, with ΔCBF/ACO₂ < 1 and 1.44 < CMRO₂ < 1.79. In all of moderate disability (MD) and good recovery (GR) patients, jugular venous pH was shown to be within the normal range, with ACBF/ACO₂ > 1 and 1.65 < CMRO₂ < 1.85. These results suggest that jugular venous pH, CO₂ response and CMRO₂, were useful as early prognostic indicators in the maintenance of neurological function.