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Vet Anaesth Analg [journal]
- Pharmacokinetics and pharmacodynamics of propofol with or without 2% benzyl alcohol following a single induction dose administered intravenously in cats. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Oct 20.
To compare the pharmacokinetics and pharmacodynamics of propofol with or without 2% benzyl alcohol administered intravenously (IV) as a single induction dose in cats.Prospective experimental study.Six healthy adult cats, three female intact, three male castrated, weighing 4.8 ± 1.8 kg.Cats received 8 mg kg(-1) IV of propofol (P) or propofol with 2% benzyl alcohol (P28) using a randomized crossover design. Venous blood samples were collected at predetermined time points to 24 hours after drug administration to determine drug plasma concentrations. Physiologic and behavioral variables were also recorded. Propofol and benzyl alcohol concentrations were determined using high pressure liquid chromatography with fluorescence detection. Pharmacokinetic parameters were described using a 2-compartment model. Pharmacokinetic and pharmacodynamic parameters were analyzed using repeated measures anova (p < 0.05).Plasma concentrations of benzyl alcohol were below the lower limits of quantification (LLOQ) at all time points for two of the six cats (33%), and by 30 minutes for the remaining four cats. Propofol pharmacokinetics, with or without 2% benzyl alcohol, were characterized by rapid distribution, a long elimination phase, and a large volume of distribution. No differences were noted between treatments with the exception of clearance from the second compartment (CLD2), which was 23.6 and 38.8 mL kg(-1) minute(-1) in the P and P28 treatments, respectively. Physiologic and behavioral variables were not different between treatments with the exception of heart rate at 4 hours post administration.The addition of 2% benzyl alcohol as a preservative minimally altered the pharmacokinetics and pharmacodynamics of propofol 1% emulsion when administered as a single IV bolus in this group of cats. These data support the cautious use of propofol with 2% benzyl alcohol for induction of anesthesia in healthy cats.
- The volume effect of lidocaine on thoracic epidural anesthesia in conscious Beagle dogs. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Oct 20.
To evaluate the volume effect of local anesthetic solution on thoracic epidural analgesia in dogs.Prospective, experimental trial.Five healthy adult Beagle dogs weighing 9.7 ± 1.3 kg.A catheter was inserted into the seventh thoracic epidural space using a lumbosacral approach, and secured with suture under total intravenous (IV) anesthesia with propofol. Each dog was administered four volume treatments (0.05, 0.10, 0.15 and 0.20 mL kg(-1) ) of 2% lidocaine via the catheter at 12 hour intervals. In every treatment, dogs were re-anesthetized with propofol (6 mg kg(-1) , IV) and isoflurane, and received iohexol at each volume to visualize the epidural distribution (ED) through computed tomography. Three hours after epidurography, when dogs had recovered from anesthesia, the appropriate volume of lidocaine was injected through the catheter, and sensory blockade (SB) in dermatomes was evaluated by pinching with a mosquito forceps. Results were presented as median (range), and the volume effect on ED and SB was analyzed with one-way Kruskal-Wallis anova.In proportion to volumes (0.05, 0.10, 0.15 and 0.20 mL kg(-1) ), there were significant increases in the extent of ED from 7.4 (5.5-9.0) to 10.4 (8.0-12.0), 13.2 (12.5-13.0), and 15.2 (13.0-18.0) vertebrae, respectively, p < 0.001, and in SB from 2.7 (1.0-5.0) to 6.8 (4.5-10.5), 9.9 (6.5-13.0), and 13.1 (11.0-15.0) dermatomes, respectively, p < 0.001. Unilateral ED and SB were observed in all treatments with various grades, and this distribution was more frequent in the low volume treatments. In the high volume treatments, temporary complications including Horner's syndrome, ataxia, paraplegia, depression, stupor, and intermittent cough occurred often.The increase in volume of local anesthetic solution improved SB by resulting in more consistent bilateral dermatome blockade as well as an extended blockade. However, caution should be exerted, as higher volume injections of lidocaine caused side effects in all dogs.
- Abstracts. [Journal Article]
- Vet Anaesth Analg 2014 Nov; 41(6):A40-90.
- Comparison of the effects of propofol or alfaxalone for anaesthesia induction and maintenance on respiration in cats. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Oct 13.
To compare the effects of propofol and alfaxalone on respiration in cats.Randomized, 'blinded', prospective clinical trial.Twenty cats undergoing ovariohysterectomy.After premedication with medetomidine 0.01 mg kg(-1) intramuscularly and meloxicam 0.3 mg kg(-1) subcutaneously, the cats were assigned randomly into two groups: group A (n = 10) were administered alfaxalone 5 mg kg(-1) minute(-1) followed by 10 mg kg(-1) hour(-1) intravenously (IV) and group P (n = 10) were administered propofol 6 mg kg(-1 ) minute(-1) followed by 12 mg kg(-1) hour(-1) IV for induction and maintenance of anaesthesia, respectively. After endotracheal intubation, the tube was connected to a non-rebreathing system delivering 100% oxygen. The anaesthetic maintenance drug rate was adjusted (± 0.5 mg kg(-1) hour(-1) ) every 5 minutes according to a scoring sheet based on physiologic variables and clinical signs. If apnoea > 30 seconds, end-tidal carbon dioxide (Pe'CO2 ) > 7.3 kPa (55 mmHg) or arterial haemoglobin oxygen saturation (SpO2 ) < 90% occurred, manual ventilation was provided. Methadone was administered postoperatively. Data were analyzed using independent-samples t-tests, Fisher's exact test, linear mixed-effects models and binomial test.Manual ventilation was required in two and eight of the cats in group A and P, respectively (p = 0.02). Two cats in both groups showed apnoea. Pe'CO2 > 7.3 kPa was recorded in zero versus four and SpO2 < 90% in zero versus six cats in groups A and P respectively. Induction and maintenance dose rates (mean ± SD) were 11.6 ± 0.3 mg kg(-1) and 10.7 ± 0.8 mg kg(-1) hour(-1) for alfaxalone and 11.7 ± 2.7 mg kg(-1) and 12.4 ± 0.5 mg kg(-1) hour(-1) for propofol.Alfaxalone had less adverse influence on respiration than propofol in cats premedicated with medetomidine. Alfaxalone might be better than propofol for induction and maintenance of anaesthesia when artificial ventilation cannot be provided.
- Comparison of midazolam and diazepam as co-induction agents with ketamine for anaesthesia in sedated ponies undergoing field castration. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Oct 13.
To compare intravenous (IV) midazolam and diazepam administered with ketamine for induction of anaesthesia in ponies, already sedated with detomidine, undergoing field castration.Prospective, randomised, 'blinded', clinical study.Twenty Welsh pony yearlings.After IV injection of detomidine (20 μg kg(-1) ) and phenylbutazone (4.4 mg kg(-1) ) ponies were allocated to receive either IV midazolam (group M) or diazepam (group D) (both 0.06 mg kg(-1) ) with ketamine (2.2 mg kg(-1) ) for induction of anaesthesia. Using simple descriptive scales, quality of sedation, induction, endotracheal intubation, surgical conditions and recovery were scored by observers blinded to treatment. Time from sedation to induction of anaesthesia, IV injection to lateral recumbency, induction to start of surgery, induction to first head lift and to standing, and total surgical time were measured. Cardiorespiratory function was assessed every 5 minutes. Time, number and total quantity of additional IV ketamine as well as any adverse effects were documented. Data were tested for normality and analysed using two-way anova with Bonferroni post hoc tests, unpaired t-tests and Mann-Whitney U tests as appropriate. Significance was set at p < 0.05.There were no significant group differences in any of the measured variables except bodyweight (mean ± SD: group M 163 ± 12 kg; group D 150 ± 7 kg; p = 0.01). One pony in group M required ketamine 15 minutes after induction of anaesthesia. Surgical conditions were good in all cases; time from induction to standing was 50 ± 11 minutes in group M and 48 ± 12 minutes in group D. There were no adverse effects. Recoveries were uneventful with minimal ataxia.Midazolam and diazepam at 0.06 mg kg(-1) can be used interchangeably in combination with ketamine for IV induction of short term anaesthesia in ponies.
- Opioid-induced adverse effects in a Holstein calf. [LETTER]
- Vet Anaesth Analg 2014 Oct 13.
- Comparison of epidural versus intrathecal anaesthesia in dogs undergoing pelvic limb orthopaedic surgery. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Oct 7.
To compare the procedural failure rate (PFR), intraoperative rescue analgesia (iRA) probability and postoperative duration of motor block after epidural and intrathecal anaesthesia in dogs undergoing pelvic limb orthopaedic surgery.Prospective, randomized clinical trial.Ninety-two client-owned dogs.Dogs were assigned randomly to receive either lumbosacral epidural anaesthesia (EA) (bupivacaine 0.5% and morphine 1%) or intrathecal anaesthesia with the same drugs in a hyperbaric solution (HIA). Inaccurate positioning of the needle, assessed by radiographic imaging, and lack of cerebral spinal fluid outflow were considered procedural failures (PFs) of EA and HIA, respectively. Fentanyl (1 μg kg(-1) IV) was provided for intraoperative rescue analgesia, when either the heart rate or the mean arterial pressure increased by 30% above the pre-stimulation value. Its use was recorded as a sign of intraoperative analgesic failure. The motor block resolution was evaluated postoperatively. Variables were compared using Fisher's exact test, the Mann-Whitney U test and the Kaplan-Meier 'survival' analysis as relevant.The PFRs in the EA and HIA groups were 15/47 (32%) and 3/45 (7%), respectively (p = 0.003). Differences in iRA were analysed in 26 and 30 subjects in the EA and HIA groups respectively, using Kaplan-Meier survival analysis. The iRA probability within the first 80 minutes of needle injection (NI) was higher in the EA group (p = 0.045). The incidence of dogs walking within 3 hours of NI was significantly higher in the HIA group (8/20, 40%) than in the EA group (0/17) (p = 0.004).HIA was found to have lower PF, lower intraoperative analgesic failure and faster motor block resolution. In this study HIA was shown to provide some advantages over EA in dogs undergoing commonly performed pelvic limb orthopaedic surgery in a day-hospital regime.
- All in a tangle: a mishap with an oesophagostomy tube in an intubated cat. [LETTER]
- Vet Anaesth Analg 2014 Oct 7.
- Cardiovascular tolerance of intravenous lidocaine in broiler chickens (Gallus gallus domesticus) anesthetized with isoflurane. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Sep 17.
To determine the cardiovascular effects of lidocaine infused intravenously (IV) in broiler chickens.Two phase study: Phase 1, randomized up-and-down study to determine effective dose 50 (ED50 ) for lidocaine; Phase 2, prospective randomized study to determine the cardiovascular effects of lidocaine.Seventeen Ross-708 broiler chickens (Gallus gallus domesticus) [11 chickens (Phase 1) and 6 chickens (Phase 2)], weighing 2.6-4.3 kg.After induction of anesthesia with isoflurane and placement of monitoring equipment including invasive blood pressure, chickens were administered lidocaine IV. During Phase 1, using an up-and-down design, each animal received a variable dose selected based on the response of the previous animal. During Phase 2, each animal was administered 6 mg kg(-1) of lidocaine IV over 2 minutes. Clinically irrelevant cardiovascular effects were defined as a relative decrease of heart rate (HR) and mean blood pressure (MAP) <30% subsequent to IV lidocaine administration. The ED50 was defined as the dose rate that would cause clinically irrelevant cardiovascular depression in 50% of the population.During Phase 1, using an up-and-down study design (n = 11), the ED50 of lidocaine was determined to be 6.30 mg kg(-1) and 6.22 mg kg(-1) (95% confidence interval, 5.30-7.13 mg kg(-1) ), when calculated by Dixon's up-and-down method, and logistic regression, respectively. During Phase 2, following infusion of lidocaine (6 mg kg(-1) ), no clinically relevant effects on HR or MAP were detected in any animal.Previous reports state that the dose of lidocaine used in birds should be ≤4 mg kg(-1) . In this study, 6 mg kg(-1) of lidocaine injected IV was not associated with adverse cardiovascular effects. These results suggest that the dose of 4 mg kg(-1) can be exceeded, at least in chickens, and opens the possibility of other therapeutic uses for lidocaine in birds.
- Comparison of three ultrasound guided approaches to the lumbar plexus in dogs: a cadaveric study. [JOURNAL ARTICLE]
- Vet Anaesth Analg 2014 Sep 4.
To assess the accuracy of contrast material injection and the dispersion of injectate following ultrasound guided injections at the level of L6 and L7, in canine cadavers.Prospective, randomized, experimental study.Twenty nine mixed breed canine cadavers (28.9 ± 6.0 kg).Three ultrasound-guided approaches to the lumbar plexus (LP) were compared: 1) a dorsal pre-iliac approach at the level of L6; 2) a lateral paravertebral approach at mid-L6; and 3) a lateral paravertebral approach at mid-L7. An isovolumic mixture of iodine-based contrast with new methylene blue (0.1 mL kg(-1) ) was injected bilaterally in the juxta-foraminal region along the L6 or L7 nerve root. Computed tomography was performed followed by segmentation and 3D reconstruction of the lumbar spine and contrast material volumes using dedicated software. Distances between contrast material and the fifth through seventh lumbar foraminae, and length of femoral (FN) and obturator (ON) nerve staining were measured and compared between approaches (p < 0.05).Injectate moved cranial and caudal to the site of injection, and dispersed into an ovoid shape between the quadratus lumborum, iliopsoas and psoas minor muscles. Injections at L7 resulted in significantly closer contrast proximity to the L6 and L7 foraminae (p < 0.001). Femoral nerve staining was similar for all approaches, ON staining was more consistent after L7 injections (p < 0.001).An ultrasound-guided lateral paravertebral approach to the LP proved very practical and accurate, with easy visualization of the plexus and associated nerves. To ensure that the ON is covered by injectate, an approach at the level of L7 is recommended. Further studies are necessary to determine if this correlates with clinically effective local anesthesia.