The effect of sevoflurane on somatically induced sympathetic reflexes.

The effects of various inspiratory concentrations of sevoflurane anesthetics on the sympathetic reflex responses evoked in the left inferior cardiac nerve branch following an electrical stimulation to the ipsilateral superficial peroneal nerve were investigated in cats. At a 2.0% inspiratory concentration of sevoflurane, two components of the somato-sympathetic reflexes with two different latencies were recorded. The early component was due to an activation of myelinated A afferent fibers (referred to as the A-reflex), while the late component was due to an activation of unmyelinated C afferent fibers (referred to as the C-reflex). The increase in the concentration of sevoflurane from 2.0% to 3.0% resulted in about 50% attenuation of both the A- and C-reflexes. A further increase in the concentration of sevoflurane to 4.0% resulted in further suppression of both reflexes.