A study comparing invasive versus oscillometric techniques for the measurement of arterial blood pressure was carried out in 4 anaesthetised sows undergoing laparoscopy. Regression analysis was used to determine the correlation coefficient.
Bias was 19.2 for systolic, 20.6 for mean and 18.8 for diastolic. Both bias and precision showed a consistent underestimation of blood pressure values recorded by oscillometry.
These results do not support the use of the oscillometric method when accurate figures for blood pressure are required in sows.
The reversal of detomidine-induced sedation with iv atipamezole was studied in 6 horses. All horses were injected iv with 10 μg and 20 μg/kg bwt detomidine and 15 min later this was followed by 6-, 8- and 10-fold doses of iv atipamezole. Atipamezole caused a quick arousal in all horses with minor side effects. Bradycardia, rhythm disturbances and head ptosis caused by detomidine were not abolished completely at the end of the 15 min observation period, even with the highest atipamezole doses. All horses remained slightly sedated but without ataxia. There were no significant differences in head height, heart rate and sedation score between the different doses of atipamezole for either dose of detomidine. According to the degree of sedation, doses of 100 μg to 160 μg/kg bwt atipamezole are adequate to antagonise detomidine-induced sedation in the horse.
Nine horses were each anaesthetised for 40 min using SufentaniVhalothane. No surgery was performed. After premedication (detomidine 5 pgkg bwt iv) induction of anaesthesia was achieved by a combination of guaiphenesinlthiopentone. Anaesthesia was maintained by inhalation of halothane (0.8%) in oxygen. Six horses (Group 1) received 1 pgkg bwt sufentanil followed by a second injection (1 pg/kg bwt) after 20 min. Three horses (Group 2) received 2 pg/kg bwt sufentanil also followed by a second injection (2 pg/kg bwt) after 20 min. Each sufentanil injection produced a slight decrease in mean arterial blood pressure with a gradual return to the initial pressure. Bradycardia was also observed. Sufentanil injection induced apnoea needing artificial ventilation. Arterial blood was sampled for analysis during the anaesthetic procedure. At the end of anaesthesia, 1 h and 24 h after rising, venous blood was sampled to determine concentrations of lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and creatine phosphokinase (CPK). Values obtained were compared with values in blood taken before premedication. Plasma glucose and lactate concentrations just before sufentanil administration, at the end of anaesthesia and 1 h after rising were compared to control values. Plasma glucose concentration increased significantly during anaesthesia but returned to normal values 1 h after rising. All other parameters stayed within physiological ranges. In both groups spontaneous respiration returned 20–25 min after the second sufentanil injection. Recovery was uneventful.
The dissociative anaesthetic ketamine is reported to provide potent analgesia after administration of subanaesthetic doses in human beings. To evaluate the analgesic effects of ketamine as an adjunct to inhalation anaesthesia in horses, haemodynamic and electroencephalographic changes were recorded for 10 min after injection of ketamine (0.5 mg/kg iv; n=7) or equal volumes of 0.9% NaCl solution (n=5) in surgically stimulated horses anaesthetised at approximately 1.3% end-tidal concentration of isoflurane. Neither the haemodynamic variables (mean arterial blood pressure and heart rate) nor the quantitated EEG variables (theta/delta ratio, alpha/delta ratio, beta/delta ratio, median power frequency) and 80% spectral edge frequency were affected significantly by the ketamine dose used. Comparing data obtained from both groups of horses, our results suggest that iv administration of 0.5 mg/kg bwt of ketamine was ineffective in suppressing haemodynamic and electroencephalographic responses to surgical stimulation.