Guilherme M. Mendes

Assessment of brachial plexus blockade in chickens by an axillary approach

OBJECTIVE To assess the brachial plexus block in chickens by an axillary approach and using a peripheral nerve stimulator. STUDY DESIGN Prospective, randomized, double-blinded study. ANIMALS Six, 84-week old, female chickens. METHODS Midazolam (1 mg kg(-1)) and butorphanol (1 mg kg(-1)) were administered into the pectoralis muscle. Fifteen minutes later, the birds were positioned in lateral recumbency and following palpation of the anatomic landmarks, a catheter was inserted using an axillary approach to the brachial plexus. Lidocaine or bupivacaine (1 mL kg(-1)) was injected after plexus localization by the nerve stimulator. Sensory function was tested before and after blockade (carpus, radius/ulna, humerus and pectoralis muscle) in the blocked and unblocked wings. The latency to onset of motor and sensory block and the duration of sensory block were recorded. A Friedman nonparametric one-way repeated-measures ANOVA was used to compare scores from baseline values over time and to compare the differences between wings at each time point. RESULTS A total of 18 blocks were performed with a success rate of 66.6% (12/18). The latency for motor block was 2.8 +/- 1.1 and 3.2 +/- 0.4 minutes for lidocaine and bupivacaine, respectively. The latencies for and durations of the sensory block were 6.0 +/- 2.5 and 64.0 +/- 18.0 and 7.8 +/- 5.8 and 91.6 +/- 61.7 minutes for lidocaine and bupivacaine, respectively. There was no statistical difference between these times for lidocaine or bupivacaine. Sensory function was not abolished in nonblocked wings. CONCLUSIONS AND CLINICAL RELEVANCE The brachial plexus block was an easy technique to perform but had a high failure rate. It might be useful for providing anesthesia or postoperative analgesia of the wing in chickens and exotic avian species that have similar wing anatomy.

Clinical use of dexmedetomidine as premedicant in cats undergoing propofol–sevoflurane anaesthesia

The purpose of this report was to evaluate the cardiorespiratory effects and efficacy of dexmedetomidine as a premedicant agent in cats undergoing ovariohysterectomy anaesthetized with propofol–sevoflurane. Cats were randomly divided into two groups of eight animals each. Dexmedetomidine (0.01 mg/kg) or 0.9% saline was administered intravenously (D and S, respectively). After 5 min, propofol was administered intravenously and anaesthesia was maintained with sevoflurane. Heart and respiratory rates, arterial blood pressure, oxygen saturation, rectal temperature and the amount of propofol needed for induction were measured. Premedication with dexmedetomidine reduced the requirement of propofol (6.7±3.8 mg/kg), but induced bradycardia, compared with the administration of saline (15.1±5.1 mg/kg). Recovery quality was significantly better in D but no significant difference in time to return of swallowing reflex was observed between groups (D=2.5±0.5 min;S=3.2±1.8 min). In conclusion, dexmedetomidine is a safe and effective agent for premedication in cats undergoing propofol–sevoflurane anaesthesia with minimal adverse effects.

INTRAOCULAR PRESSURE DETERMINATION IN CLINICALLY NORMAL RED-FOOTED TORTOISE (GEOCHELONE CARBONARIA)

Abstract Intraocular pressure (IOP) reflects a balance between aqueous humor production and outflow and is often an essential ophthalmic diagnostic procedure in animals. The objective of this study was to estimate IOP in clinically normal red-footed tortoises (Geochelone carbonaria) of various sizes by using applanation tonometry. Intraocular pressures were estimated for 25 captive red-footed tortoises (10 males, 10 females, and 5 animals of unknown sex) by using an applanation tonometer after topical anesthesia. Body length ranged from 5.1 to 54.9 cm, measured from nuchal to anal scutes. Five measurements from each eye were obtained by a single observer in an ambient temperature of approximately 30°C. Observers reliability was good (intraclass r = 0.75), and IOP did not change over the ordered sequence of five replicate measurements. For individual tortoises the correlation for IOP between the left and right eyes was low (r = 0.20). The paired t-test did not show any statistical effect (P = 0.426) for the difference in IOP between the left and right eyes. Mean IOP determined for 10 confirmed males and 10 confirmed females did not differ between sexes (P = 0.244). The mean IOP of five small tortoises (<10 cm long) was not significantly different (P = 0.244) from that of 20 large tortoises (>10 cm long). In red-footed tortoises there does not appear to be any relation between carapace length and IOP.

Infusão contínua de propofol em gatos pré-medicados com cetamina-midazolam

Anesthetic and cardiorespiratory effects of two different infusion rates of propofol were studied in cats premedicated with ketamine-midazolam. Fourteen cats were assigned to one of the two groups (TX1 or TX3). Ketamine (3.0mg/kg) and midazolam (0.3mg/kg) were administered intramuscularly. After 5 minutes, anesthesia was induced by propofol (5.0mg/kg) and maintained by a continuous infusion of propofol (0.1 and 0.3mg/kg/min, TX1 and TX3, respectively). Heart and respiratory rate, rectal temperature, oxygen hemoglobin saturation, end-tidal carbon dioxide and arterial pressure were recorded. Adequate anesthesia was observed in TX3, while animals in TX1 were only lightly sedated. A greater decrease in heart rate, arterial pressure and elevation of end-tidal dioxide carbon was observed in TX3 compared to TX1. It was concluded that administration of propofol at infusion rate of 0.3mg/kg/min provides satisfatory anesthesia, but it results in bradycardia, depression of respiratory function and arterial pressure.

O butorfanol na anestesia pela romifidina-tiletamina-zolazepam em gatos

The effect of butorphanol was investigated in six adult cats anesthetized with romifidine-tiletamine-zolazepam. Cats were given romifidine (40µg.kg-1) tiletamine (7mg.kg-1) and zolazepam (7mg.kg-1) (RTZ) intramuscularly, or RTZ and butorphanol (0.2mg.kg-1) (RTZB). Heart rate, respiratory rate, oscillometric systolic blood pressure, diastolic blood pressure and mean blood pressure, oxihemoglobin saturation and rectal temperature were determined for 120 minutes and compared to baseline values. Anesthetic effects were evaluated using a score system. Time of induction, anesthesia and recovery were also determined for comparison. Induction time and anesthetic time were significantly longer in RTZB. In the RTZB group a significant decrease in respiratory rate was observed while in the RTZ group this was transitory. Heart rate did not change in the RTZ group until 60 minutes and decreased significantly in the RTZB group from the time of injection. It is concluded that RTZ is an effective anesthetic combination with minimal cardiovascular side effects and that addition of butorphanol to this combination prolongs the anesthetic time and induces analgesia for a longer period, but causes a decrease in heart and respiratory rate in cats.

Efeitos cardiovasculares do butorfanol na anestesia por romifidina/midazolam/cetamina em gatos

Estudaram-se os efeitos cardiovasculares induzidos pelo .butorfanol em seis gatos anastesiados com romifidina/midazolam/cetamina. Administrou-se por via intramuscular, ao grupo RMK, 0,04 mg/kg de romifidina, O, 1 mg/kg de midazolam e 8 mg/kgc!e cetamina e no grupo RMKB adicionou-se 0,2 mg/kg .de butorfanol. Aferiram-se as frequencias cardiaca (FC) e respiratoria(FR), pressao arterial sistolica (PAS), diastolica (PAD) e media (PAM), saturacao parcial de oxi~hemoglobina (Sp02) e temperaturaretal (TR) durante· 60 minutos. O grau de sedacao, analgesia, miorrelaxamento, reflexo de endireitamento e respostaauditiva foram tambem subjetivamente avaliados. O grupo RMKB apresentou aumento no periodo habil anestesico, melhorsedacao e miorrelaxamento aos cinco minutos, analgesia aos dez minutos, resposta auditiva e recuperacao do reflexo deendireitamento aos 60 minutos. A reducao na FR foi similar, porem foi observada diminuicao da FC, no grupo RMKB, commanutencao da pressao arterial. Conclui-se que a adicao do butorfanol a associacao romifidina/midazolam/cetamina prolongao tempo e a qualidade de anestesia, porem reduz a frequencia cardiaca,

Alterações eletrocardiográficas em cães pré-medicados com levomepromazina e submetidos à anestesia por propofol e sevoflurano

The electrocardiographic changes were evaluated in 16 clinically healthy adult dogs, males and females, under sevoflurane anesthesia, with a mean body weight of 15±3.5kg. Levomepromazine (1.0 mg/kg) was administered intravenously, followed by induction with propofol (5.0 mg/kg). Dogs were then intubated and sevoflurane diluted in oxygen was administered using a semi-closed circuit, at a final concentration of 3.5V%. Heart and respiratory rates, pulse oximetry, capnometry, systolic, diastolic and mean arterial pressures and electrocardiographic variables were determined immediately before levomepromazine administration, 15 minutes later and immediately before induction with propofol, 15 minutes after administration of sevoflurane and thereafter every 20 minutes. After levomepromazine and sevoflurane administration there was a decrease in both systolic and mean arterial pressures. Levomepromazine caused a QT interval prolongation. Sevoflurane caused prolongation and increase in amplitude of the P wave at 70 and 130 minutes, respectively, as well as a prolongation of the QT interval. It is concluded that sevoflurane anesthesia, as done herein, caused a prolonged QT interval, with no detectable arrhythmias.