The effects of cervical epidural anesthesia on epidural somatosensory evoked potentials and phrenic nerve activities
Kasaba, T.; Inoue, T.
Masui. Japanese Journal of Anesthesiology 46(3): 321-325
1997
ISSN/ISBN: 0021-4892 PMID: 9095602 Document Number: 475396
We have investigated the effects of cervical epidural anesthesia on phrenic nerve activity (PNA), and epidural somatosensory evoked potential (SSEP) elicited by stimulation of the radial nerve in pentobarbital anesthetized cats. PNA was suppressed significantly to 72% of control value 10 min after injection of 1% lidocaine and recovered to control value within 30 min. Following 2% lidocaine injection, PNA tended to be more suppressed than with 1% lidocaine to 57% and recovered to control value within 30 min. Peak latencies of P1, N1, P2, N2, and P3 before injection of 1% lidocaine were 1.05 (0.24), 1.20 (0.11), 1.51 (0.20), 1.56 (0.34), 2.71 (0.33) (msec (SD)), respectively. Though these latencies did not increase after injection of 1% lidocaine, injection of 2% lidocaine increased them significantly and these elevations continued for 120 min. The amplitude of N2 increased significantly after injection of 1% lidocaine and the amplitude of N2 and N2-P3 increased after injection of 2% lidocaine. These results indicate that 2% lidocaine blocked the sensory nerve and the effects continued much longer than the depression of PNA by cervical epidural anesthesia.