Cerebral energy metabolism following fluid-percussion brain injury in cats

Clinical and experimental evidence suggests that head injury can cause alterations of cerebral energy metabolism. However, the etiology of this metabolic perturbation is not known. The objective of this study was to determine the effect of fluid-percussion trauma on cerebral energy metabolism. Seven ventilated chloralose-anesthetized cats were subjected to a 3.2-atm fluid-percussion brain injury. Before and for 8 hours after trauma, continuous phosphorus-31 magnetic resonance spectrography was obtained to noninvasively monitor tissue pH, phosphocreatine (PCr), and inorganic phosphate (Pi) levels. Measurement of cerebral blood flow (CBF) by the radioactive microsphere technique and calculation of oxygen and glucose consumption (CMRO₂ and CMRGl) were also performed before trauma as well as 30 minutes and 1, 2, 4 and 8 hours after trauma. Tha data showed a moderate decrease in tissue pH from 7.04 to 6.89 at 30 minutes following traum with return to control levels by 3 hours posttrauma. During the 8-hour observation period, CBF, CMRO₂, and CMRGl remained at control levels. Tissue PCr and Pi levels were also unchanged. Fluid-perdcussion trauma at the 3.2-atm level in ventilated cats causes a moderate and transient decrease in tissue pH that returns to control levels after trauma. No other metabolic changes are seen later tahn 30 minutes posttrauma. This indicates that a mild disturbance occurs after trauma in the ventilated animal and quickly returns to normal.