title: Evaluation of bispectral index (BIS) as an indicator of central nervous system depression in horses anesthetized with propofol.
abstract: The bispectral index (BIS) was evaluated as an indicator of central nervous system (CNS) depression in horses anesthetized with propofol. Five non-premedicated horses were anesthetized with 7 mg/kg, IV propofol and the minimum infusion rate (MIR) of propofol required to maintain anesthesia was determined during intermittent positive pressure ventilation in each horse. The BIS was determined 20 min later and after stabilization at 2.0 MIR, 1.5 MIR, and 1.0 MIR. The BIS was also recorded after the cessation of propofol infusion when the horses regained spontaneous breathing and swallowing reflex. The MIR and plasma concentration (Cp) of propofol were 0.20 +/- 0.03 mg/kg/min and 17.5 +/- 4.0 microg/ml, respectively. The BIS value and Cp were 59 +/- 13 and 26.7 +/- 8.6 microg/ml at 2.0 MIR, 63 +/- 9 and 22.9 +/- 9.7 microg/ml at 1.5 MIR, 64 +/- 13 and 20.1 +/- 5.9 microg/ml at 1.0 MIR, 64 +/- 24 and 13.0 +/- 2.8 microg/ml at return of spontaneous breathing, and 91 +/- 4 and 11.0 +/- 3.4 microg/ml when the swallowing reflex returned, respectively. The BIS value was significantly less in anesthetized horses compared to horses once swallowing returned (p=0.025). The BIS value was significantly correlated with the propofol Cp (r=-0.625, p=0.001). There was not a significant difference in the BIS values during the MIR multiples of propofol. The BIS was a useful indicator of awakening but did not indicate the degree of CNS depression during propofol-anesthesia in horses.
authors: Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Faculty of Environment Systems, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
authors: Kazuto
authors: K
authors: YAMASHITA
authors: Natsuki
authors: N
authors: AKASHI
authors: Yumiko
authors: Y
authors: KATAYAMA
authors: Yosuke
authors: Y
authors: UCHIDA
authors: Mohammed A
authors: MA
authors: UMAR
authors: Takaharu
authors: T
authors: ITAMI
authors: Hiroki
authors: H
authors: INOUE
authors: Richard A
authors: RA
authors: SAMS
authors: William W
authors: WW
authors: MUIR
mesh_terms: D000768:Anesthesia, General / Q000662:veterinary*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D002490:Central Nervous System / Q000187:drug effects*; D056805:Consciousness Monitors / Q000662:veterinary*; D005260:Female; D006736:Horses; D008297:Male; D015742:Propofol / Q000494:pharmacology*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol