title: Cold saline injection attenuates motor-evoked potential in the spinal cord by cortical electrical stimulation in the dog.
abstract: Changes in the motor-evoked potential of the spinal cord with transcranial stimulation are monitored for spinal cord function during thoracoabdominal aortic aneurysm surgeries. We examined the effects of changes in motor-evoked potential with cold saline injected into the clamped segment of the aorta, and compared the effects to lidocaine and warm saline injection. Eighteen dogs were divided into three groups according to the injected agents: Warm saline group (37 degrees C, 20 ml), Cold saline group (4 degrees C, 20 ml), and Lidocaine group (5.0 mg/kg of lidocaine in 20 ml of warm saline), (n=6, each group). Changes in the peak-to-peak MEP amplitude and the indirect wave (I wave) amplitude were measured during aortic cross-clamping. In the peak-to-peak MEP amplitude, the cold saline and lidocaine groups attenuated to 80% of the control value but were not significantly changed. In the I wave amplitude, the cold saline group showed a significant attenuation 1 min after injection (p<0.0001) and the lidocaine group 4 min after injection (p=0.0230), when compared with the warm saline group. Attenuation of the I wave amplitude in the cold saline group was significantly larger than that in the lidocaine group (p=0.0003). Changes in the I wave amplitude appeared within 4 min in both the cold saline and lidocaine groups. Cold saline injection into the clamped segment of the aorta is a diagnostic procedure for determining presiding critical arteries in the segment without experiencing the pharmacological side effects observed with lidocaine injection.
authors.affiliation: Department of Surgery, Division of Clinical Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Minami-ku, Hiroshima, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kumagai
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sugawara
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Isaka
authors.forename: Kenji
authors.initials: K
authors.lastname: Okada
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Orihashi
authors.forename: Taijiro
authors.initials: T
authors.lastname: Sueda
mesh_terms: D000818:Animals; D001014:Aortic Aneurysm / Q000601:surgery; D003080:Cold Temperature; D004285:Dogs; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D008012:Lidocaine; D008991:Monitoring, Physiologic; D012965:Sodium Chloride / Q000008:administration & dosage; D013116:Spinal Cord / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000175:diagnosis / Q000503:physiopathology; D020760:Spinal Cord Ischemia / Q000175:diagnosis / Q000503:physiopathology
chemical_list: D012965:Sodium Chloride; D008012:Lidocaine