Comparison of Recovery Quality Following Medetomidine versus Xylazine Balanced Isoflurane Anaesthesia in Horses: A Retrospective Analysis

Medetomidine partial intravenous anaesthesia (PIVA) has not been compared to xylazine PIVA regarding quality of recovery. This clinical retrospective study compared recoveries following isoflurane anaesthesia balanced with medetomidine or xylazine. The following standard protocol was used: sedation with 7 µg·kg−1 medetomidine or 1.1 mg·kg−1 xylazine, anaesthesia induction with ketamine/diazepam, maintenance with isoflurane and 3.5 µg·kg−1·h−1 medetomidine or 0.7 mg·kg−1·h−1 xylazine, and sedation after anaesthesia with 2 µg·kg−1 medetomidine or 0.3 mg·kg−1 xylazine. Recovery was timed and, using video recordings, numerically scored by two blinded observers. Influence of demographics, procedure, peri-anaesthetic drugs, and intraoperative complications (hypotension, hypoxemia, and tachycardia) on recovery were analysed using regression analysis (p < 0.05). A total of 470 recoveries (medetomidine 279, xylazine 191) were finally included. Following medetomidine, recoveries were significantly longer (median (interquartile range): 57 (43–71) min) than xylazine (43 (32–59) min) (p < 0.001). However, the number of attempts to stand was similar (medetomidine and xylazine: 2 (1–3)). Poorer scores were seen with increased pre-anaesthetic dose of xylazine, intraoperative tetrastarch, or salbutamol. However, use of medetomidine or xylazine did not influence recovery score, concluding that, following medetomidine–isoflurane PIVA, recovery is longer, but of similar quality compared to xylazine.

Electrocorticography based monitoring of anaesthetic depth in mice

To improve animal welfare and data quality and reproducibility during research conducted under anaesthesia, anaesthetic depth in laboratory animals must be precisely monitored and controlled. While a variety of methods have been developed to estimate the depth of anaesthesia in humans, such tools for monitoring anaesthetic depth in laboratory animals remain limited. Here we propose an epidural electrocorticogram-based monitoring system that accurately tracks the depth of anesthesia in mice receiving inhalable isoflurane anaesthesia. Several features of the electrocorticogram signals exhibit robust modulation by the concentration of the administered anesthetic, notably, corticocortical coherence serves as an excellent indicator of anaesthetic depth. We developed a gradient boosting regressor framework that utilizes the extracted features to accurately estimate the depth of anaesthesia. Our method for feature extraction and estimation is conducted with a latency of only ten seconds, establishing a system for the real-time tracking of anaesthetic depth in mice.

Effect of temperament on recovery in isoflurane-anaesthetised horses

Background: Recovery is a crucial phase of equine anaesthesia and factors influencing recovery quality are an active area of research. Aim: To investigate the effect of temperament on recovery score after isoflurane-anaesthesia in 30 adult horses undergoing elective surgery. Methods: Two veterinarians used a numerical rating scale to score each horse's response to five tests as a gauge of temperament. Owners used a numerical rating scale to score their horse's temperament according to seven behaviour-related questions. Horses underwent elective surgery under general anaesthesia using a standardised protocol. Recovery was recorded and scored by a blinded assessor using the simple descriptive scale for scoring recovery (R1) and the Edinburgh system (R2). Findings: There was no correlation between veterinarian or owner-assessed temperament and recovery score. Veterinary-assessed temperament score was negatively correlated with pre-induction romifidine and total romifidine dose. Both recovery scores were negatively correlated with anaesthetic duration and R1 was positively correlated with time to first movement in recovery. Conclusions: Temperament did not influence recovery score in our population of horses.

Cardiopulmonary Functions in Dogs under Propofol, Ketamine and Isoflurane Anaesthesia Premedicated with Glycopyrrolate, Dexmedetomidine and Butorphanol

Background: The study was conducted to evaluate the cardiopulmonary functions in dog under propofol, ketamine and isoflurane anaesthesia premedicated with dexmedetomidine and butorphanol.Methods: Four groups of dogs (A,B,C and D) comprising of six animals in each groups were premedicated with glycopyrrolate @ 0.01 mg/kg, dexmedetomidine @5ìg/kg IV and Butorphanol @ 0.1mg/kg IV. Induction was done with propofol (A and B) and with ketamine (C and D). The anaesthesia was maintained with isoflurane (A and C), propofol (B) and ketamine (D). The cardiopulmonary functions were recorded at 0 minute (before premedication) and 20 minutes, 40 minutes and 60 minutes. Result: The heart rate decreased significantly in Group B while there was a significant gradual increase in heart rate in Group D. A significant decrease in respiratory rate was observed in all the groups with a lowest value in group D. The systolic pressure decreased significantly in Group A, B and C but in Group D, the systolic pressure decreased initially at 20 minute. The diastolic pressure decreased significantly in Group A and Group B and but in group D, the diastolic pressure decreased at 20 minute. A significant decrease in mean arterial pressure was recorded in Group A, B and C. In Group D, a decrease in the mean arterial pressure was noticed at 20 minute. The SpO2 level remained near the base line values with slight variation in Group A and C where as the values remained at lower level from the base line value in Group B and D. The EtCO2 level showed non-significant changes in Group A and C. In Group B and D, the EtCO2 levels increased non-significantly with the highest value recorded in Group D. The ECG parameters remained within the normal limit with slight variation according to the heart rate.

Neurotoxicity of different amyloid beta subspecies in mice and their interaction with isoflurane anaesthesia

Background The aim of this study was to assess different amyloid beta subspecies’ effects on behaviour and cognition in mice and their interaction with isoflurane anaesthesia. Methods After governmental approval, cannulas were implanted in the lateral cerebral ventricle. After 14 days the mice were randomly intracerebroventricularly injected with Aβ 1–40 (Aβ40), Aβ 1–42 (Aβ42), 3NTyr10-Aβ (Aβ nitro), AβpE3-42 (Aβ pyro), or phosphate buffered saline. Four days after the injection, 30 mice (6 animals per subgroup) underwent general anaesthesia with isoflurane. A “sham” anaesthetic procedure was performed in another 30 mice (6 animals per subgroup, 10 subgroups in total). During the next eight consecutive days a blinded assessor evaluated behavioural and cognitive performance using the modified hole-board test. Following the testing we investigated 2 brains per subgroup for insoluble amyloid deposits using methoxy staining. We used western blotting in 4 brains per subgroup for analysis of tumour-necrosis factor alpha, caspase 3, glutamate receptors NR2B, and mGlu5. Data were analysed using general linear modelling and analysis of variance. Results Aβ pyro improved overall cognitive performance (p = 0.038). This cognitive improvement was reversed by isoflurane anaesthesia (p = 0.007), presumably mediated by decreased exploratory behaviour (p = 0.022 and p = 0.037). Injection of Aβ42 was associated with increased anxiety (p = 0.079). Explorative analysis on a limited number of brains did not reveal insoluble amyloid deposits or differences in the expression of tumour-necrosis factor alpha, NR2B, mGlu5, or caspase 3. Conclusions Testing cognitive performance after intracerebroventricular injection of different amyloid beta subspecies revealed that Aβ pyro might be less harmful, which was reversed by isoflurane anaesthesia. There is minor evidence for Aβ42-mediated neurotoxicity. Preliminary molecular analysis of biomarkers did not clarify pathophysiological mechanisms.