کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5797770 | 1111760 | 2014 | 9 صفحه PDF | دانلود رایگان |
- Horses were administered dexmedetomidine and lignocaine constant rate infusions.
- Antinociception was tested by electrically evoked nociceptive withdrawal reflexes.
- Lignocaine at 40âµg/kg/min induced robust antinociception.
- Dexmedetomidine at 4âµg/kg/h induced robust antinociception.
Dexmedetomidine and lignocaine IV are used clinically to provide analgesia in horses. The aims of this study were to investigate the antinociceptive effects, plasma concentrations and sedative effects of 2, 4 and 6âµg/kg/h dexmedetomidine IV, with a bolus of 0.96âµg/kg preceding each continuous rate infusion (CRI), and 20, 40 and 60âµg/kg/min lignocaine IV, with a bolus of 550âµg/kg preceding each CRI, in 10 Swiss Warmblood horses. Electrically elicited nociceptive withdrawal reflexes were evaluated by deltoid muscle electromyography. Nociceptive threshold and tolerance were determined by electromyography and behaviour following single and repeated stimulation. Plasma concentrations of drugs were determined by liquid chromatography and mass spectrometry. Sedation was scored on a visual analogue scale. Dexmedetomidine increased nociceptive threshold to single and repeated stimulation for all CRIs, except at 2âµg/kg/h, where no increase in single stimulation nociceptive threshold was observed. Dexmedetomidine increased nociceptive tolerance to single and repeated stimulation at all CRIs. There was large individual variability in dexmedetomidine plasma concentrations and levels of sedation; the median plasma concentration providing antinociceptive effects to all recorded parameters was 0.15âng/mL, with a range fromâ<0.02âng/mL (below the lower limit of quantification) to 0.25âng/mL. Lignocaine increased nociceptive threshold and tolerance to single and repeated stimulation at CRIs of 40 and 60âµg/kg/min, corresponding to plasma lignocaine concentrationsâ>600âng/mL. Only nociceptive tolerance to repeated stimulation increased at 20âµg/kg/min lignocaine. Lignocaine at 40âµg/kg/min and dexmedetomidine at 4âµg/kg/h were the lowest CRIs resulting in consistent antinociception. Lignocaine did not induce significant sedation.
Journal: The Veterinary Journal - Volume 202, Issue 3, December 2014, Pages 489-497