Effects of two different topographic approaches for combined sciatic and femoral nerve block in calves, guided by ultrasound and neurostimulation.

To evaluate the sensory and motor effects promoted by a combined sciatic and femoral nerve block in calves using two approaches. Six calves were used, in a crossover study. Ultrasound combined with neurostimulation, was used to perform the following block combinations: the proximal approach (PA), which consisted of the association of the parasacral approach (sciatic nerve block) and ventral to the ilium approach (femoral nerve block); distal approach (DA) consisted of the association of a lateral approach to the pelvic limb approach (sciatic nerve block), and an inguinal approach, underneath the femoral trigone (femoral nerve block). Pressure algometry and motor function of the limb where evaluated. Mechanical nociceptive threshold (MNT) increase, and ataxia duration means were 9.5 ± 0.7 kg and 10.4 ± 3.9 hr for PA and 10.4 ± 3.9 kg and 12.7 ± 1.9 hr for DA, respectively with no significant difference. There was no significant difference between MNT elevation time and the duration of ataxia using the same approach. The DA treatment showed significant MNT elevation in 72% of the tested regions, while the PA treatment showed an elevation in 100% regions tested. Topographic approaches closer to where the spinal nerves emerge produced a larger desensitised area.

Differential blockade, comparative study of different ropivacaine concentrations (0.75%; 0.2%; 0.12%) for ultrasound guided sciatic and femoral nerve blocks in calves: Prospective cross-over study.

Pharmacodynamic understanding of the different local anesthetic concentrations allows adapting their use to diverse clinical/surgical procedures, such as intraoperative and/or postoperative analgesia. A crossover study was performed, where 6 calves (5 male and 1 female), weighing 120 ± 28 Kg, were subjected to combined sciatic and femoral nerve block using three ropivacaine concentrations. The treatments were: R0.75, using 0.75% ropivacaine; R0.2, 0.2% ropivacaine; and R0.12%, 0.12% ropivacaine. All treatments were performed with ultrasound and neurostimulation assistance, and a volume of 0.1 mL/kg of the respective local anesthetic solution was administered in each block point. The sites of mechanical nociceptive threshold (MNT) evaluation were based on the calf pelvic limb dermatomes. The proportion between desensitized areas, MNT elevation time and level of ataxia were registered. Elevation of MNT occurred in 100% of the tested areas in the R0.75 and R0.2 treatments, and in 82% of the R0.12 treatment. Mean MNT elevation times were 9.5 ± 0.7 h for R0.75, 6 ± 0.8 for R.02, and 2.4 ± 2.3 for R0.12, differing significantly between all treatments. No difference was observed between MNT elevation time and ataxia duration time, in each treatment. It is concluded that the duration of sensory-motor effects is dose-dependent, but there was not possible to detect block selectivity as the concentrations was reduced. More desensitized areas and extension were obtained with the use of higher concentrations.

Comparison of two sedation protocols for diagnostic radiography in dogs with hip dysplasia.

Hip dysplasia is an alteration with a high incidence in large dogs. The aim of the study was to compare the association of xylazine or dexmedetomidine with fentanyl for radiography with joint distractor for the diagnosis of hip dysplasia. Fifteen healthy dogs, German Shepherd and Belgian Shepherd, were randomly submitted to treatments 0.2 mg/kg xylazine + 2.5 µg/kg fentanyl (XF) or 2 µg/kg dexmedetomidine + 2.5 µg/kg fentanyl (DF), intravenously. HR, f, SAP, MAP, DAP and TR were evaluated at intervals of 5 min before and after the administration of treatments; pH, PaCO2, PaO2, BE, HCO3-, SaO2, Na+, K+ and Hb at 5 and 15 min after treatment administration; and the quality of sedation at intervals of 5 min after administration of treatments. Latency, duration, and recovery times were also compared. The HR values showed a significant reduction in both groups, as well as pH, PaCO2, PaO2 and SaO2. Latency, duration and recovery times, and quality of sedation did not differ statistically between groups. Xylazine and fentanyl or dexmedetomidine and fentanyl combinations provide adequate sedation and analgesia for performing diagnostic radiographic procedures for hip dysplasia. However, oxygen supplementation is recommended to increase protocol safety.

The clinical effect of intravenous lipid emulsion on rabbits medicated with diazepam.

Intravenous lipid emulsions (ILE) have been increasingly used to reverse a wide range of lipophilic drug intoxications. However, it is still unknown if these emulsions interfere with other lipophilic drugs routinely used while treating intoxicated patients, such as diazepam, one of the main antiepileptic drugs. Therefore, the objective of the present study was to evaluate whether the administration of a 20% ILE interferes with diazepam's clinical effect. We randomly allocated thirty rabbits to five groups. Three of those groups received diazepam (1.0 mg/kg, IV), one of which did not receive any additional treatment, while the two remaining groups were treated with ILE or lactated ringer solution (1.5 mL/kg followed by 0.25 mL/kg/min for 30 min). The fourth group only received lipid emulsion, and the fifth only lactated ringer. Successive neurological exams at 20 min intervals for a total of 100 min were performed to assess the rabbits' neurological state. We concluded that the ILE did not interfere with diazepam's clinical effect but, although unlikely, the possibility of recurrence of a sedative effect should be considered.

Effect of Dexmedetomidine Low Doses with or without Midazolam in Cats: Clinical, Hemodynamic, Blood Gas Analysis, and Echocardiographic Effects.

Objectives: The aim of the study is to compare the sedative, cardiorespiratory, echocardiographic, and blood gas effects of dexmedetomidine and methadone associated or not with midazolam for restraint chemistry in cats. Methods: Eighteen healthy young cats (4.06 ± 0.48 kg) were randomly sedated with two protocols, through the intramuscular route: dexmedetomidine (5 µg.kg-1), methadone (0.3 mg. kg-1) and midazolam (0.3 mg. kg-1) (DMTM, n = 9), or dexmedetomidine (7.5 µg.kg-1) and methadone (0.3 mg. kg-1) (DMT, n = 9). The cardiorespiratory parameters were measured at baseline, 5 and 10 minutes after pharmacological latency. The sedation, analgesia, and muscle relaxation scores were assessed before and 5 minutes after pharmacological latency, while arterial blood gas analysis and echocardiography were assessed before and after 10 or 15 minutes, respectively. Results: There was no difference between the protocols regarding the cardiorespiratory, blood gas, and echocardiographic parameters used. The scores for sedation, analgesia, and muscle relaxation also did not differ between the protocols, with the degree of sedation, analgesia, and myorelaxation considered satisfactory in both groups. A significant decrease in heart rate (HR) was observed after administration of the sedative protocols, reaching a maximum reduction at T10 (46% and 53% reduction in the DMT and DMTM groups, respectively). The reduction in HR had an impact on echocardiographic parameters such as CO, which decreased 53% and 56% in the DMT and DMTM groups, respectively. There was a significant reduction in PaO2, SaO2, ejection fraction, and fractional shortening in both protocols. SpO2 decreased significantly after 5 minutes of sedation in the DMT group, but with a minimum mean SpO2 of 92% in T5. The respiratory rate decreased significantly at 5 and 10 minutes in the DMTM group, while PaCO2 increased in both groups, indicating respiratory depression caused by the drugs. Conclusions and Relevance. The study pointed out that both sedative protocols can be recommended for clinical sedation of young and healthy cats in the doses used. However, both protocols resulted in cardiorespiratory depression in cats and also the particularities of the animals should be evaluated regarding reducing cardiac output by more than 50%.

Comparison of midazolam and butorphanol combined with ketamine or dexmedetomidine for chemical restraint in howler monkeys (Alouatta guariba clamitans) for vasectomy.

BACKGROUND: This study evaluated and compared cardiorespiratory and blood gas parameters, as well as sedation, analgesia and recovery of two protocols: ketamine (10 mg/kg) or dexmedetomidine (10 µg/kg), with midazolam (0.5 mg/kg) and butorphanol (0.3 mg/kg), IM (KBM and DBM, respectively) in brown howler monkeys (Alouatta guariba clamitans). MATERIAL AND METHODS: Twelve brown howler monkeys were selected in two groups and evaluated for cardiorespiratory parameters and sedation, from 5-30 minutes after latency. Blood gas and arterial lactate were taken at 5 and 30 minutes. In the end, time and quality of recovery were evaluated. RESULTS: The HR in DBM group was significantly lower at all times. The sedation score was higher in DBM. Recovery in DBM was faster. All animals had moderate hypoxaemia. CONCLUSION: Both protocols produce satisfactory anaesthesia and analgesia, but DBM provides deeper sedation with faster recovery. Oxygen supplementation is recommended in both due to hypoxaemia.