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1.

Objective

To compare the effects of two balanced anaesthetic protocols (isoflurane–dexmedetomidine versus medetomidine) on sedation, cardiopulmonary function and recovery in horses.

Study design

Prospective, blinded, randomized clinical study.

Animals

Sixty healthy adult warm blood horses undergoing elective surgery.

Methods

Thirty horses each were sedated with dexmedetomidine 3.5 μg kg?1 (group DEX) or medetomidine 7 μg kg?1 (group MED) intravenously. After assessing and supplementing sedation if necessary, anaesthesia was induced with ketamine/diazepam and maintained with isoflurane in oxygen/air and dexmedetomidine 1.75 μg kg?1 hour?1 or medetomidine 3.5 μg kg?1 hour?1. Ringer's lactate (7–10 mL kg?1 hour?1) and dobutamine were administered to maintain normotension. Controlled mechanical ventilation maintained end-tidal expired carbon dioxide pressures at 40–50 mmHg (5.3–6.7 kPa). Heart rate, invasive arterial blood pressure, inspired and expired gas composition and arterial blood gases were measured. Dexmedetomidine 1 μg kg?1 or medetomidine 2 μg kg?1 was administered for timed and scored recovery phase. Data were analysed using two-way repeated-measures analysis of variance and chi-square test. Significance was considered when p  0.05.

Results

In group DEX, significantly more horses (n = 18) did not fulfil the sedation criteria prior to induction and received one or more supplemental doses, whereas in group MED only two horses needed one additional bolus. Median (range) total sedation doses were dexmedetomidine 4 (4–9) μg kg?1 or medetomidine 7 (7–9) μg kg?1. During general anaesthesia, cardiopulmonary parameters did not differ significantly between groups. Recovery scores in group DEX were significantly better than in group MED.

Conclusions and clinical relevance

Horses administered dexmedetomidine required more than 50% of the medetomidine dose to reach equivalent sedation. During isoflurane anaesthesia, cardiopulmonary function was comparable between the two groups. Recovery scores following dexmedetomidine were better compared to medetomidine.  相似文献   

2.

Objective

To determine the effects of low and high dose infusions of dexmedetomidine and a peripheral α2-adrenoceptor antagonist, MK-467, on sevoflurane minimum alveolar concentration (MAC) in dogs.

Study design

Crossover experimental study.

Animals

Six healthy, adult Beagle dogs weighing 12.6 ± 0.9 kg (mean ± standard deviation).

Methods

Dogs were anesthetized with sevoflurane in oxygen. After a 60-minute instrumentation and equilibration period, the MAC of sevoflurane was determined in triplicate using the tail clamp technique. PaCO2 and temperature were maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa) and 38 ± 0.5 ºC, respectively. After baseline MAC determination, dogs were administered two incremental loading and infusion doses of either dexmedetomidine (1.5 μg kg?1 then 1.5 μg kg?1 hour?1 and 4.5 μg kg?1 then 4.5 μg kg?1 hour?1) or MK-467 (90 μg kg?1 then 90 μg kg?1 hour?1 and 180 μg kg?1 then 180 μg kg?1 hour?1); loading doses were administered over 10 minutes. MAC was redetermined in duplicate starting 30 minutes after the start of drug administration at each dose. End-tidal sevoflurane concentrations were corrected for calibration and adjusted to sea level. A repeated-measures analysis was performed and comparisons between doses were conducted using Tukey's method. Statistical significance was considered at p < 0.05.

Results

Sevoflurane MAC decreased significantly from 1.86 ± 0.3% to 1.04 ± 0.1% and 0.57 ± 0.1% with incremental doses of dexmedetomidine. Sevoflurane MAC significantly increased with high dose MK-467, from 1.93 ± 0.3% to 2.29 ± 0.5%.

Conclusions and clinical relevance

Dexmedetomidine caused a dose-dependent decrease in sevoflurane MAC, whereas MK-467 caused an increase in MAC at the higher infusion dose. Further studies evaluating the combined effects of dexmedetomidine and MK-467 on MAC and cardiovascular function may elucidate potential benefits of the addition of a peripheral α2-adrenergic antagonist to inhalation anesthesia in dogs.  相似文献   

3.

Objective

Influence of detomidine or romifidine constant rate infusion (CRI) on plasma lactate concentration and isoflurane requirements in horses undergoing elective surgery.

Study design

Prospective, randomised, blinded, clinical trial.

Animals

A total of 24 adult healthy horses.

Methods

All horses were administered intramuscular acepromazine (0.02 mg kg?1) and either intravenous detomidine (0.02 mg kg?1) (group D), romifidine (0.08 mg kg?1) (group R) or xylazine (1.0 mg kg?1) (group C) prior to anaesthesia. Group D was administered detomidine CRI (10 μg kg?1 hour?1) in lactated Ringer's solution (LRS), group R romifidine CRI (40 μg kg?1 hour?1) in LRS and group C an equivalent amount of LRS intraoperatively. Anaesthesia was induced with ketamine and diazepam and maintained with isoflurane in oxygen. Plasma lactate samples were taken prior to anaesthesia (baseline), intraoperatively (three samples at 30 minute intervals) and in recovery (at 10 minutes, once standing and 3 hours after end of anaesthesia). End-tidal isoflurane percentage (Fe′Iso) was analysed by allocating values into three periods: Prep (15 minutes after the start anaesthesia–start surgery); Surgery 1 (start surgery–30 minutes later); and Surgery 2 (end Surgery 1–end anaesthesia). A linear mixed model was used to analyse the data. A value of p < 0.05 was considered significant.

Results

There was a difference in plasma lactate between ‘baseline’ and ‘once standing’ in all three groups (p < 0.01); values did not differ significantly between groups. In groups D and R, Fe′Iso decreased significantly by 18% (to 1.03%) and by 15% (to 1.07%), respectively, during Surgery 2 compared with group C (1.26%); p < 0.006, p < 0.02, respectively.

Conclusions and clinical relevance

Intraoperative detomidine or romifidine CRI in horses did not result in a clinically significant increase in plasma lactate compared with control group. Detomidine and romifidine infusions decreased isoflurane requirements during surgery.  相似文献   

4.

Objective

To determine the effects of two dexmedetomidine continuous rate infusions on the minimum infusion rate of alfaxalone for total intravenous anaesthesia (TIVA), and subsequent haemodynamic and recovery effects in Greyhounds undergoing laparoscopic ovariohysterectomy.

Study design

Prospective, randomized and blinded clinical study.

Animals

Twenty-four female Greyhounds.

Methods

Dogs were premedicated with dexmedetomidine 3 μg kg?1 and methadone 0.3 mg kg?1 intramuscularly. Anaesthesia was induced with IV alfaxalone to effect and maintained with a TIVA mixture of alfaxalone in combination with two different doses of dexmedetomidine (0.5 μg kg?1 hour?1 or 1 μg kg?1 hour?1; groups DEX0.5 and DEX1, respectively). The alfaxalone starting dose rate was 0.07 mg kg?1 minute?1 and was adjusted (± 0.02 mg kg?1 minute?1) every 5 minutes to maintain a suitable depth of anaesthesia. A rescue alfaxalone bolus (0.5 mg kg?1 IV) was administered if dogs moved or swallowed. The number of rescue boluses was recorded. Heart rate, arterial blood pressure and arterial blood gas were monitored. Qualities of sedation, induction and recovery were scored. Differences between groups were tested for statistical significance using a Student’s t test or Mann–Whitney U test as appropriate.

Results

There were no differences between groups in sedation, induction and recovery quality, the median (range) induction dose of alfaxalone [DEX0.5: 2.2 (1.9–2.5) mg kg?1; DEX1: 1.8 (1.2–2.9) mg kg?1], total dose of alfaxalone rescue boluses [DEX0.5: 21.0 (12.5–38.8) mg; DEX1: 22.5 (15.5–30.6) mg] or rate of alfaxalone (DEX0.5: 0.12 ± 0.04 mg kg?1 minute?1; DEX1: 0.12 ± 0.03 mg kg?1 minute?1).

Conclusions and clinical relevance

Co-administration of dexmedetomidine 1 μg kg?1 hour?1 failed to reduce the dose rate of alfaxalone compared with dexmedetomidine 0.5 μg kg?1 hour?1 in Greyhounds undergoing laparoscopic ovariohysterectomy. The authors recommend an alfaxalone starting dose rate of 0.1 mg kg?1 minute?1. Recovery quality was good in the majority of dogs.  相似文献   

5.

Objective

To evaluate intraoperative and postoperative efficacy of ultrasound (US)-guided femoral (FN) and obturator (ON) nerves block, in the iliopsoas muscle compartment (IPM), using an in-plane technique.

Study design

Anatomical research and randomized, prospective, ‘blinded’ clinical study.

Animals

Six dog cadavers and 20 client-owned dogs undergoing tibial plateau levelling osteotomy (TPLO) surgery.

Methods

In phase 1, anatomical dissections and US imaging of the IPM were performed to design an US-guided nerve block involving the FN and ON simultaneously. The technique was considered successful if new methylene blue solution injection (0.1 mL kg?1) stained FN–ON for ≥2 cm. In phase 2, the US-guided nerve block designed in phase 1, combined with US-guided sciatic nerve (ScN) block, was performed in 20 dogs undergoing TPLO surgery. Patients were assigned randomly to one of two treatment groups: ropivacaine 0.3% (R3, n = 10) and ropivacaine 0.5% (R5, n = 10) at a volume of 0.1 mL kg?1 for each nerve block. Intraoperative success rate (fentanyl requirement < 2.1 mcg kg?1 hour?1) and postoperative pain score [Short Form-Glasgow Composite Measure Pain Scale (SF-GCMPS) ≥ 5/20] were evaluated.

Results

In phase 1, the US image of FN–ON was detected between L6 and L7. In-plane needling technique produced a staining of >4 cm in six of six cases. No abdominal or epidural dye spread was found. In phase 2, median fentanyl infusion rates were 0.5 (0.0–0.9) μg kg?1 hour?1 for R3 and 0.6 (0.0–2.2) μg kg?1 hour?1 for R5. At 9 and 11 hours after the peripheral nerve blocks, an SF-GCMPS ≥ 5 was observed for R3 and R5, respectively.

Conclusions and clinical relevance

The US-guided FN–ON block in the IPM, using an in-plane technique, combined with US-guided ScN block, provided sufficient analgesia to minimize the use of fentanyl during TPLO surgery. A longer postoperative analgesia was observed in group R5 compared with R3.  相似文献   

6.

Objective

To study the effects of MK-467, a peripheral α2-adrenoceptor antagonist, on sedation, heart rate and blood pressure after intramuscular (IM) coadministration with 25 μg kg?1 of dexmedetomidine in cats.

Study design

Prospective, randomized, controlled, blinded, cross-over, experimental study.

Animals

A total of eight healthy, adult, neutered male cats.

Methods

Cats were administered five IM treatments at least 2 weeks apart, consisting of dexmedetomidine 25 μg kg?1 (D25), MK-467 600 μg kg?1 (M600) and D25 combined with 300, 600 and 1200 μg kg?1 of MK-467 (D25M300, D25M600 and D25M1200, respectively). Heart rate and direct arterial blood pressure were recorded via telemetry and sedation assessed prior to treatments and at intervals for 8 hours thereafter.

Results

Heart rate decreased significantly after all treatments with dexmedetomidine and remained below baseline up to 240 (D25), 20 (D25M300) and 3 minutes (D25M600 and D25M1200). Mean arterial pressure (MAP) increased with D25, remained unchanged with M600 and decreased over time with all combination treatments. The highest and lowest MAP after each treatment were 168 ± 17 and 100 ± 14 (D25), 157 ± 18 and 79 ± 11 (D25M300), 153 ± 11 and 74 ± 10 (D25M600), 144 ± 12 and 69 ± 7 (D25M1200) and 136 ± 9 and 104 ± 13 mmHg (M600). All treatments with dexmedetomidine produced sedation although its duration was significantly reduced by the addition of MK-467.

Conclusions and clinical relevance

Dexmedetomidine induced bradycardia and hypertension, which were attenuated by all three doses of MK-467. The duration of sedation was reduced by MK-467. MK-467 may improve the cardiovascular tolerance of IM dexmedetomidine in cats.  相似文献   

7.

Objective

To assess the temporal effects of a single fentanyl intravenous (IV) bolus on the minimum anesthetic concentration (MAC) of isoflurane in chickens and to evaluate the effects of this combination on heart rate (HR) and rhythm, systemic arterial pressures (sAP) and ventilation.

Study design

Prospective experimental trial.

Animals

Seventeen adult chickens weighing 1.8 ± 0.2 kg.

Methods

Individual isoflurane MAC for 17 chickens was previously determined using the bracketing method. Chickens were anesthetized with isoflurane to evaluate the effects of a single IV fentanyl bolus (10 or 30 μg kg?1) on isoflurane MAC over time using the up-and-down method. Ventilation was controlled. The isoflurane MAC reduction was estimated by logistic regression at 5 and 15 minutes after fentanyl administration. In the second phase, seven chickens were anesthetized with isoflurane, and fentanyl was administered (30 μg kg?1) IV over 1 minute during spontaneous ventilation and HR and rhythm, sAP and ventilation variables were measured.

Results

At 5 minutes after IV administration of fentanyl (10 or 30 μg kg?1), isoflurane MAC was significantly reduced by 17.6% (6.1–29.1%) [logistic regression estimate (95% Wald confidence interval)] and 42.6% (13.3–71.9%), respectively. Isoflurane MAC reduction at 15 minutes after IV administration of fentanyl (10 or 30 μg kg?1) was 6.2% (?0.6 to 12.9%) and 13.2% (?0.9 to 27.3%), respectively; however, this reduction was not significant. No clinically significant cardiopulmonary changes or arrhythmias were detected after the administration of fentanyl (30 μg kg?1).

Conclusions and clinical relevance

Administration of a single fentanyl bolus induced a dose-dependent and short-lasting reduction in isoflurane MAC. The higher dose induced no significant cardiopulmonary depression in isoflurane-anesthetized chickens during spontaneous ventilation. In chickens anesthetized with isoflurane, the clinical usefulness of a single fentanyl bolus is limited by its short duration of effect.  相似文献   

8.

Objective

The aim of the study was to evaluate the influence of tramadol on acute nociception in dogs.

Study design

Experimental, blinded, randomized, crossover study.

Animals

Six healthy laboratory Beagle dogs.

Methods

Dogs received three treatments intravenously (IV): isotonic saline placebo (P), tramadol 1 mg kg?1 (T1) and tramadol 4 mg kg?1 (T4). Thermal thresholds were determined by ramped contact heat stimulation (0.6 °C second?1) at the lateral thoracic wall. Mechanical thresholds (MT) were measured using a probe containing three blunted pins which were constantly advanced over the radial bone, using a rate of force increase of 0.8 N second?1. Stimulation end points were defined responses (e.g. skin twitch, head turn, repositioning, vocalization) or pre-set cut-out values (55 °C, 20 N). Thresholds were determined before treatment and at predetermined time points up to 24 hours after treatment. At each measurement point, blood was collected for determination of O-desmethyltramadol concentrations. The degree of sedation and behavioural side effects were recorded. Data were analysed by one-way anova and two-way anova for repeated measurements.

Results

Thermal nociception was not influenced by drug treatment. Mechanical nociception was significantly increased between P and T1 at 120 and 240 minutes, and between P and T4 at 30, 60, 240 and 420 minutes. T1 and T4 did not differ. O-desmethyltramadol (M1) maximum plasma concentrations (Cmax) were 4.2 ± 0.8 ng mL?1 and 14.3 ± 2.8 ng mL?1 for T1 and T4, respectively. Times to reach maximum plasma concentrations (Tmax) were 27.6 ± 6.3 minutes for T1 and 32.1 ± 7.8 minutes for T4. No sedation occurred. There were signs of nausea and mild to moderate salivation in both groups.

Conclusion and clinical relevance

Tramadol was metabolized marginally to O-desmethyltramadol and failed to produce clinically relevant acute antinociception. Therefore, the use of tramadol for acute nociceptive pain is questionable in dogs.  相似文献   

9.

Objective

To investigate the pharmacokinetics of buprenorphine and its main active metabolite, norbuprenorphine, after administration of an intravenous loading dose followed by constant rate infusion (CRI) in dogs.

Study design

Prospective, clinical study.

Animals

A total of seven healthy dogs undergoing elective ovariectomy.

Methods

Buprenorphine was administered as a loading dose (intravenous bolus of 15 μg kg?1) followed by CRI (2.5 μg kg?1 hour?1 for 6 hours). Moreover, intraoperative analgesia was supplemented by an intramuscular carprofen (4 mg kg?1) injection, administered prior to surgery, and by lidocaine, administrated through subcutaneous infiltration and through a splash on the ovarian vascular pedicle during surgery. Pain and sedation were scored for all animals throughout the 24-hour study period and rescue analgesia was administered when a visual analogue scale score was > 40 mm. Blood samples were collected from a jugular catheter at regular intervals, and plasma concentrations of buprenorphine and norbuprenorphine were determined by a validated liquid chromatography–tandem mass spectrometry method.

Results

Buprenorphine showed a two-compartment kinetic profile. Maximum concentration was 23.92 ± 8.64 ng mL?1 at 1 minute (maximum time); elimination half-life was 41.87 ± 17.35 minutes; area under the curve was 486.68 ± 125.66 minutes ng?1 mL?1; clearance was 33.61 ± 13.01 mL minute?1 kg?1, and volume of distribution at steady state was 1.77 ± 0.50 L kg?1. In no case was rescue analgesia required. Norbuprenorphine resulted below the lower limit of quantification in almost all samples.

Conclusions and clinical relevance

The results suggest that a buprenorphine CRI can be a useful tool for providing analgesia in postoperative patients, considering its minor side effects and the advantages of a CRI compared to frequent boluses. The negligible contribution of norbuprenorphine to the therapeutic effect was confirmed.  相似文献   

10.

Objective

To determine the effect of fentanyl on the induction dose of propofol and minimum infusion rate required to prevent movement in response to noxious stimulation (MIRNM) in dogs.

Study design

Crossover experimental design.

Animals

Six healthy, adult intact male Beagle dogs, mean ± standard deviation 12.6 ± 0.4 kg.

Methods

Dogs were administered 0.9% saline (treatment P), fentanyl (5 μg kg?1) (treatment PLDF) or fentanyl (10 μg kg?1) (treatment PHDF) intravenously over 5 minutes. Five minutes later, anesthesia was induced with propofol (2 mg kg?1, followed by 1 mg kg?1 every 15 seconds to achieve intubation) and maintained for 90 minutes by constant rate infusions (CRIs) of propofol alone or with fentanyl: P, propofol (0.5 mg kg?1 minute?1); PLDF, propofol (0.35 mg kg?1 minute?1) and fentanyl (0.1 μg kg?1 minute?1); PHDF, propofol (0.3 mg kg?1 minute?1) and fentanyl (0.2 μg kg?1 minute?1). Propofol CRI was increased or decreased based on the response to stimulation (50 V, 50 Hz, 10 mA), with 20 minutes between adjustments. Data were analyzed using a mixed-model anova and presented as mean ± standard error.

Results

ropofol induction doses were 6.16 ± 0.31, 3.67 ± 0.21 and 3.33 ± 0.42 mg kg?1 for P, PLDF and PHDF, respectively. Doses for PLDF and PHDF were significantly decreased from P (p < 0.05) but not different between treatments. Propofol MIRNM was 0.60 ± 0.04, 0.29 ± 0.02 and 0.22 ± 0.02 mg kg?1 minute?1 for P, PLDF and PHDF, respectively. MIRNM in PLDF and PHDF was significantly decreased from P. MIRNM in PLDF and PHDF were not different, but their respective percent decreases of 51 ± 3 and 63 ± 2% differed (p = 0.035).

Conclusions and clinical relevance

Fentanyl, at the doses studied, caused statistically significant and clinically important decreases in the propofol induction dose and MIRNM.  相似文献   

11.
12.

Objective

The combination of butorphanol, azaperone and medetomidine (BAM) with subsequent antagonism by naltrexone–yohimbine or naltrexone–atipamezole was evaluated for reversible immobilization of captive African lions (Panthea leo).

Study design

Prospective, clinical trial.

Animals

Twenty lions, 11 males and nine females, weighing 38–284 kg were immobilized in South Africa.

Methods

The BAM volume dose rate administered was 0.005–0.008 mL kg?1 (0.6 mL 100 kg?1). Physiologic variables were recorded every 5 minutes. Four arterial blood samples were collected from all animals at 20, 30, 40 and 50 minutes after immobilization for analysis of blood-gases and acid-base status.

Results

The actual doses administered were as follows: butorphanol, 0.18 ± 0.03 mg kg?1; azaperone, 0.07 ± 0.01 mg kg?1; and medetomidine, 0.07 ± 0.01 mg kg?1. The inductions were calm and smooth, and induction time ranged from 4 to 10 minutes (7 ± 2 minutes). The amount of time needed to work with each lion was 70 minutes, and no additional drug doses were needed. Heart rate (40 ± 8 beats minute?1) and respiratory frequency (15 ± 4 breaths minute?1) were stable throughout immobilization. The mean arterial blood pressure of all animals was stable but elevated (142 ± 16 mmHg). The rectal temperature slightly increased over time but remained within acceptable range. The recovery time was significantly shorter when using naltrexone and atipamezole (9 ± 1 minutes) compared to using naltrexone and yohimbine (22 ± 7 minutes).

Conclusion and clinical relevance

The BAM combination proved to be reliable for general veterinary anaesthesia in lions. During anaesthesia, minor veterinary procedures such a blood collection, intubation, vaccination and collaring could safely be performed with no additional dosing required.  相似文献   

13.

Objective

We investigated the plasma concentrations and cardiovascular effects of intramuscularly (IM) administered medetomidine, administered alone or with three different doses of MK-467.

Study design

Prospective, randomized, open, crossover trial.

Animals

Eight purpose-bred healthy Beagle dogs.

Methods

Each dog was administered four treatments: medetomidine 20 μg kg–1 IM alone or mixed in the same syringe with MK-467 (200 μg kg–1, 400 μg kg–1 or 600 μg kg–1). Instrumentation was performed under standardized anaesthesia. The dogs were allowed to recover before measurement of baseline values. Composite sedation scores, cardiovascular variables, i.e., heart rate (HR), cardiac output (CO), mean arterial and central venous blood pressures (MAP and CVP) and arterial blood gases were recorded at baseline and for 60 minutes after treatment. Drug concentrations in venous plasma were analysed. Generalized linear mixed models for repeated measures with post hoc Bonferroni correction were used with statistical significance level set at α = 0.05.

Results

All treatments initially demonstrated the effects of medetomidine: HR and CO decreased and CVP increased. MAP transiently increased and then significantly decreased from baseline with the two highest MK-467 doses. The cardiovascular effects of medetomidine disappeared more rapidly with MK-467 than with medetomidine alone. With medetomidine alone, sedation scores remained high until the end of the 60 minute follow-up. Maximum concentrations of medetomidine were more rapidly achieved and were higher with MK-467.

Conclusions and clinical relevance

Initial haemodynamic effects of medetomidine were not prevented by MK-467, but these effects were attenuated and their duration shortened by MK-467, independently of dose. Absorption of medetomidine was accelerated by MK-467, when administered concomitantly IM, resulting in faster sedation; addition of MK-467 shortened the sedative effect of medetomidine.  相似文献   

14.

Objective

To characterise, as a clinical study, the pharmacokinetics and pharmacodynamics and describe the hypnotic effect of the neurosteroid alfaxalone (3α-hydroxy-5 α-pregnane-11, 20-dione) formulated with 2-hydroxypropyl-β-cyclodextrin in male and female rats.

Study design

Prospective, experimental laboratory study.

Animals

A total of 12 (six male and six female) adult, aged-matched Sprague Dawley rats.

Methods

Surgery and instrumentation was performed under isoflurane anaesthesia in an oxygen/nitrous oxide mixture (1:2) and local anaesthetic infiltration. All animals received a loading dose (1.67 mg kg?1 minute?1) for 2.5 minutes followed by a constant rate infusion (0.75 mg kg?1 minute?1) for 120 minutes of alfaxalone. Isoflurane and nitrous oxide was discontinued 2.5 minutes after the alfaxalone infusion started. Cardiorespiratory variables (heart rate, respiratory rate, arterial blood pressure and end tidal carbon dioxide tension) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Carotid artery blood samples were collected at strategic time points for blood gas analysis, haematology, biochemistry, and plasma concentrations of alfaxalone. Plasma samples were assayed using liquid chromatography-mass spectrometry.

Results

There were significant differences between the sexes for plasma clearance (p = 0.0008), half-life (p = 0.0268) and mean residence time (p = 0.027). Mean arterial blood pressure was significantly higher in the male rats (p = 0.0255).

Conclusions and clinical relevance

This study confirms that alfaxalone solubilised in 2-hydroxypropyl-β-cyclodextrin provides excellent total intravenous anaesthesia in rats. Sex-based differences in pharmacokinetics and pharmacodynamics were demonstrated and must be considered when designing biomedical research models using alfaxalone.  相似文献   

15.

Objective

To determine the dose of cis-atracurium needed to produce a moderate neuromuscular blockade (NMB) in pigs.

Study design

Prospective experimental study.

Animals

Seven pigs [five females and two males; median (range) body weight: 47 (36–64) kg].

Methods

Pigs were premedicated with intramuscular midazolam (0.3 mg kg?1) and ketamine (7 mg kg?1). Anaesthesia was induced with intravenous (IV) propofol 3 (1–4) mg kg?1 and maintained with isoflurane in oxygen. Based on a preliminary study, the subjects were administered 0.3 mg kg?1 cis-atracurium followed by 0.48 mg kg?1 hour?1 constant rate infusion (CRI) IV. A moderate NMB was defined as a train-of-four (TOF) count of ≤2 by acceleromyography. When the TOF count was >2, 0.1 mg kg?1 cis-atracurium was administered and the CRI was increased. The cis-atracurium CRI was decreased when the TOF count was under 2 for more than 15 minutes. The total dose of cis-atracurium required to maintain a moderate NMB was calculated as the total amount of cis-atracurium used (both CRI and supplementary boluses) divided by the administration time.

Results

The cis-atracurium CRI lasted for 87 (76–151) minutes. To induce and maintain a moderate neuromuscular blockade, the initial dose of cis-atracurium was 0.3 (0.3– 0.5) mg kg?1 and the CRI was 0.71 (0.37–0.98) mg kg?1 hour?1.

Conclusions and clinical relevance

The doses described in our study may help researchers obtain a moderate NMB using cis-atracurium in pigs.  相似文献   

16.

Objective

To assess the efficacy of psoas compartment and sacral plexus block for pelvic limb amputation in dogs.

Study design

Prospective clinical study.

Animals

A total of 16 dogs aged 8 ± 3 years and weighing 35 ± 14 kg (mean ± standard deviation).

Methods

Dogs were administered morphine (0.5 mg kg?1) and atropine (0.02 mg kg?1); anesthesia was induced with propofol and maintained with isoflurane. Regional blocks were performed before surgery in eight dogs with bupivacaine (2.2 mg kg?1) and eight dogs were administered an equivalent volume of saline. The lumbar plexus within the psoas compartment was identified using electrolocation lateral to the lumbar vertebrae at the fourth–fifth, fifth–sixth and sixth–seventh vertebral interspaces. The sacral plexus, ventrolateral to the sacrum, was identified using electrolocation. Anesthesia was monitored using heart rate (HR), invasive blood pressure, electrocardiography, expired gases, respiratory frequency and esophageal temperature by an investigator unaware of the group allocation. Pelvic limb amputation by coxofemoral disarticulation was performed. Dogs that responded to surgical stimulation (>10% increase in HR or arterial pressure) were administered fentanyl (2 μg kg?1) intravenously for rescue analgesia. Postoperative pain was assessed at extubation; 30, 60 and 120 minutes; and the morning after surgery using a visual analog scale (VAS).

Results

The number of intraoperative fentanyl doses was fewer in the bupivacaine group (2.7 ± 1.1 versus 6.0 ± 2.2; p < 0.01). Differences in physiologic variables were not clinically significant. VAS scores were lower in bupivacaine dogs at extubation (0.8 ± 1.9 versus 3.8 ± 2.5) and at 30 minutes (1.0 ± 1.4 versus 4.3 ± 2.1; p < 0.05).

Conclusions and clinical relevance

Psoas compartment (lumbar plexus) and sacral plexus block provided analgesia during pelvic limb amputation in dogs.  相似文献   

17.

Objective

To evaluate skin temperature increase as an early predictive measure for evaluating epidural and femoral-sciatic block success in dogs.

Study design

Prospective clinical trial.

Animals

A total of 29 dogs undergoing orthopaedic surgery on one hindlimb.

Methods

Dogs were anaesthetized and placed into lateral recumbency with the affected limb uppermost and the coat was clipped. Baseline infrared thermographic images (T0) of the affected limb, of the paw pad of the affected leg and of the ipsilateral paw pad were taken. Subsequently, dogs were administered either an epidural (EPI; n = 11) or a femoral–sciatic block (FS; n = 18) using bupivacaine 1 mg kg?1. Then, 2 minutes after placement of the block, thermographic images were obtained every 3 minutes for a total of four measurements (T1–T4) and surgery was commenced. Rescue analgesia consisting of fentanyl 1 μg kg?1 was administered if needed. A regional block was considered successful if the dose of fentanyl administered was less than the lower 95% confidence interval of the geometric mean of the total fentanyl used in each group. A ≥ 1 °C increase of skin temperature was considered as the minimum increase required for detection of a successful block.

Results

A total of 12 out of 18 blocks in the FS and eight of 11 in the EPI group were considered successful based on fentanyl consumption. Out of these, only four of 12 in the FS and one of eight in the EPI group developed an increase in temperature of ≥ 1 °C. Contrarily, four of six of the nonsuccessful cases in the FS and three of three in the EPI group developed an increase in temperature of ≥ 1 °C.

Conclusions and clinical relevance

Contrary to reports in humans, thermography did not indicate regional block success prior to surgery in dogs. However further studies under more controlled conditions are needed to determine whether thermography can be used to indicate failure of regional blockade.  相似文献   

18.

Objective

To evaluate the effect of hyaluronidase on uptake, duration and speed of elimination of xylazine–tiletamine–zolazepam administered in the subcutaneous fat over the dorsal lumbar region of swine.

Study design

Blinded, randomized, crossover study.

Animals

Six healthy Landrace/Large White pigs weighing 132 ± 24 kg (mean ± standard deviation).

Methods

Animals were administered xylazine (1 mg kg?1) and tiletamine–zolazepam (8 mg kg?1) (control treatment, CON), or xylazine–tiletamine–zolazepam at the same doses with hyaluronidase (400 IU) (treatment HYA). The treatments were administered into the dorsal lumbar adipose tissue, 2.5–3.0 cm laterally from the spinous process of the second lumbar vertebra. The latency, anesthesia and recovery periods were measured. Heart rate, noninvasive systolic, diastolic, and mean arterial pressures, respiratory rate, hemoglobin oxygen saturation and rectal temperature were recorded every 10 minutes for up to 50 minutes.

Results

One animal in CON and one animal in HYA were responsive to stimulation and did not allow safe handling. No significant difference was found between treatments for latency (CON 11.3 ± 5.9 minutes, HYA 7.4 ± 5.1 minutes) and anesthesia (CON 53 ± 53 minutes, HYA 49 ± 38 minutes) periods. Recovery period was shorter in HYA (9 ± 6 minutes) than in CON (32 ± 16 minutes) (p < 0.05). Physiological variables were not significantly changed over time and were within accepted normal clinical limits for the species in both treatments.

Conclusion and clinical relevance

Hyaluronidase (400 IU) administered into adipose tissue in pigs did not reduce the latency and duration of dissociative anesthesia, but was associated with faster recovery.  相似文献   

19.

Objective

To evaluate the onset, magnitude and duration of thermal antinociception after oral administration of two doses of tapentadol in cats.

Study design

Prospective, randomized, blinded, experimental study.

Animals

Six healthy adult cats weighing 4.4 ± 0.4 kg.

Methods

Skin temperature (ST) and thermal threshold (TT) were evaluated using a wireless TT device up to 12 hours after treatment. Treatments included placebo (PBO, 50 mg dextrose anhydrase orally), buprenorphine (BUP, 0.02 mg kg?1) administered intramuscularly, low-dose tapentadol (LowTAP, 25 mg orally; mean 5.7 mg kg?1) and high-dose tapentadol (HighTAP, 50 mg orally; mean 11.4 mg kg?1) in a blinded crossover design with 7 day intervals. Statistical analysis was performed using anova with appropriate post hoc test (p ≤ 0.05).

Results

Salivation was observed immediately following 11 out of 12 treatments with tapentadol. The ST was significantly increased at various time points in the opioid treatments. Hyperthermia (≥ 39.5 °C) was not observed. Baseline TT was 45.4 ± 1.4 °C for all treatments. Maximum TT values were 48.8 ± 4.8 °C at 1 hour in LowTAP, 48.5 ± 3.0 °C at 2 hours in HighTAP and 50.2 ± 5.3 °C at 1 hour in BUP. TT significantly increased after LowTAP at 1 hour, after HighTAP at 1–2 hours, and after BUP at 1–2 hours compared with baseline values. TTs were significantly increased in BUP at 1–2 hours compared with PBO.

Conclusion and clinical relevance

Oral administration of tapentadol increased ST and TT in cats. The durations of thermal antinociception were similar between HighTAP and BUP, both of which were twice as long as that in LowTAP. Studies of different formulations may be necessary before tapentadol can be accepted into feline practice.  相似文献   

20.

Objective

To evaluate the ability of a noninvasive cardiac output monitoring system with electrical velocimetry (EV) for predicting fluid responsiveness in dogs undergoing cardiac surgery.

Study design

Prospective experimental trial.

Animals

A total of 30 adult Beagle dogs.

Methods

Stroke volume (SV), stroke volume variation (SVV) and cardiac index were measured using the EV device in sevoflurane-anaesthetized, mechanically ventilated dogs undergoing thoracotomies for experimental creation of right ventricular failure. The dogs were considered fluid responsive if stroke volume (SVI; indexed to body weight), measured using pulmonary artery thermodilution, increased by 10% or more after volume loading (10 mL kg–1). Relationships of SVV, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) with SVI were analysed to estimate fluid responsiveness.

Results

Better prediction of fluid responsiveness, with a significant area under the receiver operating characteristic curve, was observed for SVV (0.85 ± 0.07; p = 0.0016) in comparison with CVP (0.65 ± 0.11; p = 0.17) or PAOP (0.60 ± 0.12; p = 0.35), with a cut-off value of 13.5% (84% specificity and 73% sensitivity).

Conclusions and clinical relevance

SVV derived from EV is useful for identification of dogs that are likely to respond to fluids, providing valuable information on volume status under cardiothoracic anaesthesia.  相似文献   

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