Effects of detomidine or romifidine during maintenance and recovery from isoflurane anaesthesia in horses.

OBJECTIVE: To evaluate the effects of detomidine or romifidine on cardiovascular function, isoflurane requirements and recovery quality in horses undergoing isoflurane anaesthesia. STUDY DESIGN: Prospective, randomized, blinded, clinical study. ANIMALS: A total of 63 healthy horses undergoing elective surgery during general anaesthesia. METHODS: Horses were randomly allocated to three groups of 21 animals each. In group R, horses were given romifidine intravenously (IV) for premedication (80 µg kg-1), maintenance (40 µg kg-1 hour-1) and before recovery (20 µg kg-1). In group D2.5, horses were given detomidine IV for premedication (15 µg kg-1), maintenance (5 µg kg-1 hour-1) and before recovery (2.5 µg kg-1). In group D5, horses were given the same doses of detomidine IV for premedication and maintenance but 5 µg kg-1 prior to recovery. Premedication was combined with morphine IV (0.1 mg kg-1) in all groups. Cardiovascular and blood gas variables, expired fraction of isoflurane (Fe'Iso), dobutamine or ketamine requirements, recovery times, recovery events scores (from sternal to standing position) and visual analogue scale (VAS) were compared between groups using either anova followed by Tukey, Kruskal-Wallis followed by Bonferroni or chi-square tests, as appropriate (p < 0.05). RESULTS: No significant differences were observed between groups for Fe'Iso, dobutamine or ketamine requirements and recovery times. Cardiovascular and blood gas measurements remained within physiological ranges for all groups. Group D5 horses had significantly worse scores for balance and coordination (p = 0.002), overall impression (p = 0.021) and final score (p = 0.008) than group R horses and significantly worse mean scores for VAS than the other groups (p = 0.002). CONCLUSIONS AND CLINICAL RELEVANCE: Detomidine or romifidine constant rate infusion provided similar conditions for maintenance of anaesthesia. Higher doses of detomidine at the end of anaesthesia might decrease the recovery quality.

Description of different ultrasound guided transversus abdominis plane block in pig cadavers - A pilot study.

OBJECTIVE: To develop an ultrasound (US)-guided transversus abdominis plane (TAP) block in pigs. STUDY DESIGN: Prospective, descriptive, experimental study. ANIMALS: A total of 26 hemi-abdomens belonging to 13 Seghers Hybrid cadavers. METHODS: The study consisted of two parts. In part 1, a preliminary anatomical understanding of the abdominal wall innervation in pigs was established (two hemi-abdomens of one pig). Part 2 was divided into three phases, and a US-guided TAP technique using methylene blue dye (0.3 mL kg-1 for each hemi-abdomen) was developed. In chronological order, a pilot study (phase I) was conducted to establish good injection points (four hemi-abdomens). In phase II a two-point injection technique (10 hemi-abdomens) was performed. A cranial injection was made at two-thirds of the distance between the xyphoid process and the iliac crest, immediately ventral to the rib arch. A caudal injection was performed ventral to the last rib. In phase III a three-point injection technique was performed (10 hemi-abdomens) with an extra injection point halfway between the cranial and caudal injection point. Staining of the different nerves was recorded during dissection. RESULTS: In part 1 the nerves innervating the pig's abdominal wall, thoracic vertebrae 12-16 (T12-16) and lumbar vertebrae 1-3 (L1-3), were identified. In part 2, data from the pilot study, adequate nerve staining with the two- or three-point injection technique, were obtained in T12 (29 versus 45% respectively), T13 (29 versus 100%), T14 (73 versus 45%), T15 (75 versus 78%), T16 (58 versus 78%), L1 (100 versus 75%), L2 (88 versus 84%) and L3 (23 versus 0%). CONCLUSIONS AND CLINICAL RELEVANCE: US-guided TAP block can be used in swine but only a moderate success rate for adequate nerve staining was achieved in this study. Further studies are necessary to determine a correct injection volume and assess clinical intra- and postoperative efficacy.

How to score sedation and adjust the administration rate of sedatives in horses: a literature review and introduction of the Ghent Sedation Algorithm.

OBJECTIVE: To summarize the different methods used to assess sedation and/or adjust the dose or administration rate of alpha-2 agonists in horses and to propose an algorithm to adjust the administration rate of a constant rate infusion of an alpha-2 agonist in horses. DATABASES USED: PubMed and Web of Science; search terms: horse, sedation and score. CONCLUSIONS: Most authors distinguish between sedation depth, sedation quality and degree of ataxia. These three features are evaluated using scoring systems similar to those classically used to assess pain, i.e. simple descriptive scales, numerical rating scales (NRS), visual analogue scales and/or multifactorial sedation scales. In addition, head height above the ground is often used as a measure of the depth of sedation. Very few authors have described how to adjust the administration rate or dose of alpha-2 agonists. Based on the available literature, the Ghent Sedation Algorithm was developed, which assigns scores (NRS) for degree of ataxia, sedation depth and surgical conditions, and uses these to prescribe changes in the administration rate of constant rate infusions of alpha-2 agonists. Studies are needed to validate this algorithm.