Cerebral Effects of Propofol following Bolus Administration in Sheep

Abstract

The effects of bolus administration of propofol (50 mg, 100 mg and 200 mg) on cerebral blood flow and cerebral metabolic rate for oxygen were examined in a chronically catheterized sheep preparation. Depth of anaesthesia was simultaneously measured using a withdrawal response to a noxious electrical stimulus and it was demonstrated that the 100 mg dose induced moderate sedation while the 200 mg dose induced relatively deep anaesthesia. Propofol caused transient dose-dependent decreases in cerebral blood flow, despite minimal changes in blood pressure. These were accompanied by parallel decreases in cerebral metabolic rate but no change in cerebral oxygen extraction. As cerebrovascular responses in the sheep appear similar to those in man, the parallel changes in cerebral blood flow and metabolic rate demonstrated in this study supports the suitability of propofol as a neuroanaesthetic agent.

Regional cerebral blood flow and glucose metabolism during propofol anaesthesia in healthy subjects studied with positron emission tomography

“…Studies in human and animal subjects have demonstrated that propofol induces dose‐dependent decreases in cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO 2 ) and intracranial pressure Neuronal activation in the brain is assumed to be coupled by parallel changes in regional metabolism and CBF . However, regarding regional changes, the total CMRO 2 is a fairly insensitive indicator of varying neuronal activity .…”

Total intraven�se An�sthesie

“…Die rasche Injektion von Propofol führt aber zu hohen Plasmaspitzenkonzentrationen [69]. Hohe Plasmapeaks von Propofol sind Ursache kurzzeitiger Abfälle des Herzminutenvolumens [117] bzw.…”

Propofol: Effects on the Central Nervous System

“…Ludbrook et al [9] evaluated the effects of bolus doses of propofol on CBF and CMRO 2 in a chronically instrumented sheep model. CBF was measured by a Doppler transducer placed through a burr hole directly over the superior sagittal sinus using the venous outflow method.…”

“…Its effect on ICP is greater than that of hyperventilation and control of ICP with propofol restored SEPs in an animal model of intracranial hypertension [8]. Animal models have also demonstrated that propofol decreases both CBF and CMRO 2 [9,10,12]. The decrease in CBF and SCBF are greater in the forebrain than in the hindbrain or the spinal cord [12–14].…”

“…The decrease in CBF and SCBF are greater in the forebrain than in the hindbrain or the spinal cord [12–14]. The decrease in CBF is linked to decreases in CMRO 2 [9] as well as the cerebral metabolic rate for glucose [13,14]. Some of the initial animal studies have suggested that the decrease in CBF is greater than the decrease in CMRO 2 [10,17]; however, these findings have been attributed to the concomitant use of other anesthetic agents and/or decreases in the MAP [9].…”