Effects of isoflurane anesthesia on F-waves in the sciatic nerve of the adult rat.

INTRODUCTION: Nerve conduction studies provide insights into the functional consequences of axonal and myelin pathology in peripheral neuropathies. We investigated whether isoflurane inhalation anesthesia alters F-wave latencies and F-persistence in the sciatic nerve of adult rats. METHODS: Ten rats were investigated at 3 different isoflurane concentrations followed by ketamine-xylazine injection anesthesia. To assess F-wave latencies, a stimulation paradigm was chosen to minimize H-reflex masking of F-waves. RESULTS: F-wave persistence rates were reduced with 3.5% isoflurane concentration at 4 and 10 Hz supramaximal stimulation and marginally reduced with 2.5% isoflurane when compared with ketamine-xylazine. F-wave amplitudes decreased progressively with rising stimulus frequency in all types of anesthesia and most at 3.5% isoflurane concentration. CONCLUSIONS: The type of anesthesia and the stimulus repetition rate have an impact on some F-wave parameters. Higher isoflurane concentrations and repetition rates are not recommended in experimental studies using rat neuropathy models where F-waves are of interest.