Lidocaine accelerates neuroelectrical recovery after incomplete global ischemia in rabbits

The use of high-dose lidocaine for cerebral protection during ischemia has produced varied results. Our study uses a new, single carotid artery preparation in the rabbit to produce incomplete global ischemia by graded carotid occlusion; specific electroencephalographic changes are used as the end point for the extent of blood flow reduction sustained during 20 minutes. We monitored arterial pressure, intracranial pressure, and internal carotid blood flow that were recorded with an electromagnetic flowmeter after surgical ligation of the opposite internal and the two vertebral arteries, and we studied the electroencephalogram and somatosensory-evoked potentials elicited by stimulation of the sciatic nerve. Low-dose lidocaine (0.2 mg/kg/min) infused throughout the experiment significantly accelerated the time course of the return of electroencephalographic and evoked-potential amplitudes toward control. Deep halothane anesthesia alone elicited the slowest recovery, suggesting that the action of lidocaine was independent of its general anesthetic effect. There were very small differences among the groups in the measured arterial pressure, intracranial pressure, and cerebral blood flow, suggesting that lidocaine changed recovery rate without markedly modifying any characteristic of the postischemic cerebral perfusion. The protective effect of lidocaine may be the result of a specific blockade of Na+ channels or a decrease in excitatory neurotransmitter release, either of which would cause a delay in the onset of the events that lead to neuronal damage during ischemia.