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1.

Objective

Mitral valve (MV) regurgitation due to degenerative MV disease is the leading cause of cardiac death in dogs. We carried out preliminary experiments to determine the feasibility and short-term effects of beating-heart MV repair using an expanded polytetrafluorethylene (ePTFE) chordal implantation device (Harpoon TSD-5) in dogs.

Animals

This study involved six healthy purpose-bred Beagles (weight range 8.9–11.4 kg).

Material and methods

Following a mini-thoracotomy performed under general anesthesia, the TSD-5 was used to place 1 or 2 artificial ePTFE cords on the anterior MV leaflet or the posterior MV leaflet via a left-ventricular transapical approach. The procedure was guided and monitored by transesophageal echocardiography. Postoperative antithrombotic treatment consisted of clopidogrel or a combination of clopidogrel and apixaban. Dogs were serially evaluated by transthoracic echocardiography at day 1, 7, 14, 21, and 30. The hearts were then examined for evaluation of tissues reactions and to detect signs of endothelialization.

Results

One or two chords were successfully implanted in five dogs. Four dogs completed the 30 days follow-up. One dog died intra-operatively because of aortic perforation. One dog died early post-operatively from a hemorrhagic pleural effusion attributed to overly aggressive antithrombotic treatment. One dog developed a thrombus surrounding both the knot and the synthetic cord. Postmortem exam confirmed secure placement of ePTFE knots in the mitral leaflets in all dogs and the presence of endothelialization of the knots and chords.

Conclusions

These preliminary results demonstrate the feasibility of artificial chordal placement using an ePTFE cordal implantation device in dogs.  相似文献   

2.

Objective

To evaluate the use of an experimental colloid model for teaching veterinary anesthesia residents ultrasound-guided technique for nerve blockade.

Study design

Prospective, blinded and randomized.

Methods

Colloid models were constructed for practice in ultrasound-guided needle location. Nine veterinary anesthesia residents with no prior experience of ultrasound-guided technique for nerve blocks were randomly divided into three groups. Each group received theoretical orientation. Two groups were assigned to practical training using the experimental model: group 1 (G1) received 2 hours of training and group 2 (G2) received 1 hour of training prior to testing with specific tasks. Group 3 (G3) received no practical training. During testing, the time required for task completion (e.g., display of structures and positioning a needle) and the number of failures were recorded.

Results

The average times to completion of the tasks and the number of technical failures were: G1, 47 seconds and 1 failure; G2, 68 seconds and 2 failures; G3, 187 seconds and 7 failures.

Conclusions and clinical relevance

In residents with no prior experience of ultrasound-guided needle placement, using an experimental colloid model and a longer training period was associated with increased accuracy and decreased time to task completion. Based on the results of this study, training with an experimental model can be recommended to improve the speed and accuracy of needle manipulation using ultrasound in clinicians with no prior experience of ultrasound-guided technique.  相似文献   

3.

Objective

To assess the ability to visually detect fade during train-of-four (TOF) or double burst stimulation (DBS) in anesthetized dogs recovering from nondepolarizing neuromuscular block.

Study design

Online anonymous survey.

Population

Data from 112 participants.

Methods

A web-based survey containing 12 videos of the response to ulnar nerve stimulation with TOF and 12 with DBS obtained at different levels of recovery from rocuronium-induced block was distributed to participants of the American College of Veterinary Anesthesia and Analgesia and the Academy of Veterinary Technicians in Anesthesia and Analgesia e-mail lists. Participants were asked to provide their highest training degree in anesthesiology, watch each video no more than twice, and determine whether fade was present. The probability to correctly recognize fade was calculated using binomial general linear models. General linear models and Tukey’s tests were used to assess the effects of level of neuromuscular block, pattern of stimulation, and observers’ training on the probability to detect fade.

Results

The survey was completed by 53 diplomates, 29 licensed veterinary technicians, 24 residents and six doctors of veterinary medicine (DVMs). The probability to detect fade decreased as partial neuromuscular block became more shallow (p < 0.0001). A TOF or DBS ratio of 0.7 had a 50% chance of being detected. DBS was superior to TOF for detecting fade when the ratio was 0.3–0.69. TOF was superior to DBS when the ratio was 0.7–0.9 (p < 0.0001). There were no differences among groups of observers when assessing fade with TOF or DBS.

Conclusions and clinical relevance

Detection of fade from observations of the response to TOF in dogs is unreliable. Advance training in anesthesiology or the use of DBS confers little to no advantage for this subjective test.  相似文献   

4.

Objectives

To describe signalment, clinical characteristics, diagnostic, treatment, and outcome data in a large case series of cats with patent ductus arteriosus (PDA).

Animals

Fifty cats with confirmed PDA.

Methods

Retrospective review of medical records from five referral veterinary hospitals for cats with PDA between 2000 and 2015. Cats were included if a PDA was visualized echocardiographically, during surgery, or on post-mortem examination.

Results

Median age at presentation was 6 months (range: 36 days–9.7 years; n = 50), and sex distribution was approximately equal (27 male, 23 female). Most cats did not have clinical signs (70.2%; 33/47) at the time of presentation. Murmurs were classified as continuous (55%; 22/40) or systolic (45%; 18/40). Echocardiography confirmed left-to-right shunting in 33 cats (82.5%; 33/40) and right-to-left shunting in 7 (17.5%; 7/40). Concurrent cardiac anomalies were identified in 54.5% (18/33) and pulmonary hypertension in 45.7% (16/35). Closure was pursued in 68% (34/50), and complications associated with the procedure occurred in 14.7% (5/34) of cats, including one intraoperative mortality. Long-term follow up was available in 80% (40/50) of cats.

Conclusions

Cats with PDA often do not display clinical signs and may not have the characteristic physical examination findings typical of PDA in dogs. An increased prevalence of concurrent cardiac anomalies and pulmonary hypertension were found relative to previous reports. Thoracic radiographs and echocardiogram may provide the most comprehensive information for making a diagnosis and treatment recommendations. PDA closure was associated with a favorable long-term outcome in cats included in this study.  相似文献   

5.

Objective

To describe a transorbital approach to the maxillary nerve block in dogs and compare it with a traditional approach.

Study design

Prospective, randomized controlled study.

Animals

Heads from 17 euthanized dogs (10 Greyhounds, three Border Collies and four of mixed breed).

Methods

A volume of 1 mL of methylene blue dye was injected by each of two techniques, a traditional percutaneous approach and a transorbital approach to the maxillary nerve block. Both techniques were used on each head, alternating the left and right sides after random assignment to the first head. The heads were dissected to reveal the maxillary nerve and the length of nerve stained was measured.

Results

There was no significant difference (p = 0.67) in the proportion of nerves stained for a length >6 mm by either technique (88.2% transorbital versus 82.3% percutaneous). The mean length of nerve stained did not differ significantly between the techniques (p = 0.26).

Conclusions and clinical relevance

The transorbital approach to the maxillary nerve block described here presents a viable alternative to the traditional percutaneous approach. Further study is required to confirm its efficacy and safety under clinical conditions.  相似文献   

6.

Objective

To describe an ultrasound-guided approach for venous and arterial vascular access and catheterization in anesthetized adult Yorkshire cross-bred pigs.

Study design

Prospective experimental study.

Animals

Ten adult female Yorkshire cross-bred pigs, weighing 78.4 ± 5.6 kg (mean ± standard deviation).

Methods

Using ultrasound guidance and the Seldinger technique, a 7 Fr, 20 cm triple-lumen central venous catheter was placed in the external jugular vein and an 18 gauge, 16 cm catheter was placed in the femoral artery. The success rate of catheterization and the incidence of catheter patency over 24 hours of general anesthesia were recorded.

Results

Catheterization of the external jugular vein was successful in 10 out of 10 pigs and catheterization of the femoral artery was successful in eight out of 10 pigs. A surgical dissection technique on the femoral artery was performed in two pigs. Venous and arterial catheter patency was maintained in all pigs over the 24 hour study period.

Conclusions and clinical relevance

Ultrasound guidance resulted in success rates of 100% for catheterization of the external jugular vein and 80% for catheterization of the femoral artery in anesthetized adult Yorkshire cross-bred pigs. This technique is a noninvasive, easily performed alternative to surgical exposure of the vessels in large pigs undergoing surgical instrumentation for biomedical device testing.  相似文献   

7.

Introduction

The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC).

Animals

A total of 239 horses or ponies were studied, including 65 warmbloods, 33 Standardbreds, 41 Thoroughbreds, 32 Arabian horses, 28 draft horses, and 40 ponies aged from 1 day to 30 years, weighing from 18 to 890 kg, with no evidence of cardiac disease.

Methods

For each horse or pony, a two-dimensional and M-mode echocardiography was performed. Within each breed, the relationships between BW or TC and echocardiographic dimensions were examined using power regression equations. Predictions and their 95% prediction intervals were calculated for the echocardiographic measurements.

Results

Within each breed, all echocardiographic measurements showed a significant and positive relationship with a high coefficient of determination for the estimation of the regression equations using BW and TC as the main explanatory variables. Breed-specific power regression equations as well as the 95% prediction intervals were calculated for each echocardiographic measurement as a function of BW and TC.

Conclusions

In the future, the body size-corrected and breed-specific echocardiographic reference values calculated in the present study could be used to discriminate between normal and abnormal values in a given animal.  相似文献   

8.

Objectives

1) To determine which peripheral artery commonly used for invasive arterial blood pressure (IBP) monitoring yields the least bias when compared with noninvasive blood pressure (NIBP) values obtained at the antebrachium of the dog, and 2) to identify and describe differences in systolic (SAP), mean (MAP) and diastolic arterial pressures (DAP) among different anatomical locations.

Study design

Prospective experimental study.

Animals

Twenty adult hound dogs weighing 24.5 ± 1.1 kg (mean ± standard deviation).

Methods

Four peripheral arteries—dorsal pedal, median caudal, intermediate auricular and superficial palmar arteries—were catheterized with 20 gauge, 3.8 cm catheters. One NIBP cuff was placed in the middle third of the antebrachium. Four sets of IBP and NIBP measurements were simultaneously collected every 2 minutes. A linear mixed model was performed to analyze the collected data.

Results

IBP values varied depending on the arterial catheterization site. The difference was greater for SAP. NIBP measured at the antebrachium had the best agreement with IBP measured at the median caudal artery.

Conclusion and clinical relevance

IBP varies among anatomical locations. The smallest bias and narrowest limits of agreement were obtained at the median caudal artery, providing the best overall agreement with the equipment studied. The median caudal artery may be the preferable anatomical location for clinical comparison studies between IBP and NIBP in dogs when the cuff is on the antebrachium.  相似文献   

9.

Objective

To assess agreement between noninvasive blood pressure (NIBP) oscillometrically-derived values from a multiparameter monitor (Datex Ohmeda S/5 Compact) with those obtained by invasive blood pressure (IBP) measurement in anaesthetised horses undergoing elective surgery.

Study design

Prospective clinical study.

Animals

A total of 40 healthy adult horses.

Methods

Horses were anaesthetised with various anaesthetic protocols (based on clinical requirements). Depending on positioning, cannulation of the facial or lateral metatarsal artery was performed for IBP measurement. The cannula was connected via a transducer to the monitor. An appropriately sized NIBP cuff was placed around the tail base and connected to the same monitor. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial blood pressures were continuously recorded from the invasive system, and at 3 minute intervals from the oscillometric system, throughout the surgical procedure using a Datex iCollect program. An appropriate arithmetic correction factor was applied to the oscillometric results where the cuff was not level with the heart. Assessment of the degree of agreement between invasive and noninvasive readings at each time point was performed using a modified Bland-Altman analysis.

Results

While in many horses there was relatively close correlation between the values obtained over time, there was substantial variability in individual animals which resulted in wide Bland-Altman limits of agreement. The oscillometric device over-reads by approximately 32, 23 and 22 mmHg, and under-reads by 26, 17 and 19 mmHg for SAP, MAP and DAP, respectively, compared with the IBP values. However, using the mean difference and standard deviation, the device conforms to American College of Veterinary Internal Medicine (ACVIM) standards.

Conclusions and clinical relevance

Oscillometric blood pressure measurement using the Datex Ohmeda S/5 Compact multiparameter monitor conforms to ACVIM standards when the NIBP cuff is placed on the tail. However, because of the wide variability in measurements, we cannot recommend this technique to guide therapy in anaesthetised adult horses.  相似文献   

10.

Objective

The evaluation of alfaxalone as a premedication agent and intravenous anaesthetic in pigs.

Study design

Prospective, clinical trial.

Animals

Nine healthy, 6–8-week-old female Landrace pigs weighing 22.2 ± 1.0 kg, undergoing epidural catheter placement.

Methods

All pigs were premedicated with 4 mg kg?1 alfaxalone, 40 μg kg?1 medetomidine and 0.4 mg kg?1 butorphanol administered in the cervical musculature. Sedation was subjectively scored by the same observer from 1 (no sedation) to 10 (profound sedation) prior to induction of anaesthesia with alfaxalone intravenously to effect. All pigs were maintained on alfaxalone infusions with the rate of administration adjusted to maintain appropriate anaesthetic depth. Quality of induction was scored from 1 (poor) to 3 (smooth) and basic cardiorespiratory variables were recorded every 5 minutes during anaesthesia. Results are reported as mean ± standard deviation or median (range) as appropriate.

Results

Sedation scores were 9 (7–10). Inductions were smooth in all pigs and cardiovascular variables remained within normal limits for the duration of anaesthesia. The induction dose of alfaxalone was 0.9 (0.0–2.3) mg kg?1. Three pigs did not require additional alfaxalone after premedication to facilitate intubation.

Conclusions and clinical relevance

Intramuscular alfaxalone in combination with medetomidine and butorphanol produced moderate to deep sedation in pigs. Alfaxalone produced satisfactory induction and maintenance of anaesthesia with minimal cardiovascular side effects. Appropriate monitoring of pigs premedicated with this protocol is required as some pigs may become anaesthetized after intramuscular administration of this combination of drugs.  相似文献   

11.

Objectives

To determine whether the Enterprise point-of-care blood analysis system (EPOC) produces results in agreement with two other blood gas analysers in regular clinical use (i-STAT and Radiometer ABL77) and to investigate the precision of the new machine when used with equine whole blood.

Study design

Prospective, randomized, non-blinded, comparative laboratory analyser study.

Animals

Horses admitted to a university teaching hospital requiring arterial or venous blood gas analysis as part of their routine clinical management.

Methods

One hundred equine blood samples were run immediately, consecutively and in randomized order on three blood gas analysers. Results of variables common to all three analysers were tested for agreement and compared with guidelines used in human medicine. These require 80% of results from the test analyser to fall within a defined range or percentage of results from the comparator devices to achieve acceptability. Additionally, 21 samples were run twice in quick succession on the EPOC analyser to investigate precision.

Results

Agreement targets were not met for haematocrit, haemoglobin and base excess for either i-STAT or ABL77 analysers. EPOC precision targets were not met for partial pressure of carbon dioxide, ionized calcium, haematocrit and haemoglobin. Overall comparative performance of the EPOC was good to excellent for pH, oxygen tension, potassium, bicarbonate and oxygen saturation of haemoglobin, but marginal to poor for other parameters.

Conclusions and clinical relevance

The EPOC may be useful in performing analysis of equine whole blood, but trend analysis of carbon dioxide tension, ionized calcium, haematocrit and haemoglobin should be interpreted with caution. The EPOC should not be used interchangeably with other blood gas analysers.  相似文献   

12.

Objectives

To determine the prevalence of mitral valve regurgitation (MR) in asymptomatic Swedish Norfolk terriers.

Animals

Seventy-nine privately owned Norfolk terriers.

Materials and methods

A prospective observational study was conducted where dogs were recruited via the Swedish Norfolk terrier club. All dogs were examined using the same protocol including physical examination and Doppler echocardiography.

Results

Fifteen dogs (19%) had a murmur at the time of the examination. A total of 35 dogs (44%) had MR, including 23 dogs (29%) with both MR and tricuspid valve regurgitation and 12 dogs (15%) with MR only, identified on Doppler echocardiography. In addition, 7 dogs (9%) had tricuspid valve regurgitation only. The prevalence of MR increased with increasing age (p < 0.0001).

Conclusions

Mitral valve regurgitation is common in asymptomatic Norfolk terriers with and without murmurs and the prevalence increases with age. The impact of MR in this breed on survival remains to be elucidated by a longitudinal study.  相似文献   

13.

Background

False tendons (FTs) are string-like structures in the left ventricle. A FT might produce focal thickening at its insertion region of the left ventricle, which could be mistaken for focal hypertrophic cardiomyopathy.

Objectives

To perform a prospective, echocardiographic follow-up examination of feline FTs and compare the wall thickness at the FT insertion region and a normal region without FTs at both examinations.

Animals

One hundred twenty-eight cats with one or multiple FTs without other cardiac abnormalities or systemic disease.

Methods

Measurements of the interventricular septum at end-diastole at a region with and without FT insertion were performed using two-dimensional echocardiography at both examinations and compared statistically using a Student's t-test.

Results

The follow-up interval ranged from 5 to 110 months (mean, 33 months). Myocardial wall segments with FT insertions were significantly thicker compared with neighboring wall regions in the long axis, but not in the short-axis views obtained. Comparing the wall thickness of follow-up examinations with the initial examination, revealed a significant growth of both FT and non-FT segments. However, differences in growth between the FT region and region without FTs were not statistically different.

Conclusions and clinical importance

Many normal cats have FTs, associated with focal thickening compared with neighboring regions. This thickening can increase over time, proportionate to growth in other (non-FT) segments. The association of such thickening with an FT and the absence of disproportionate growth in this segment over time suggests that these segments are simply thicker related to FT insertion.  相似文献   

14.

Objective

To characterize the cardiovascular effects of dexmedetomidine, with or without MK-467, following intravenous (IV) administration in cats.

Study design

Prospective Latin square experimental study.

Animals

Six healthy adult purpose-bred cats.

Methods

Cats were anesthetized with desflurane in oxygen for instrumentation with a carotid artery catheter and a thermodilution catheter in the pulmonary artery. One hour after discontinuation of desflurane, cats were administered dexmedetomidine (25 μg kg–1), MK-467 (600 μg kg–1), or dexmedetomidine (25 μg kg–1) and MK-467 (600 μg kg–1). All treatments were administered IV as a bolus. Cardiovascular variables were measured prior to drug administration and for 8 hours thereafter. Only data from the dexmedetomidine and dexmedetomidine–MK-467 treatments were analyzed.

Results

Dexmedetomidine produced significant decreases in heart rate, cardiac index and right ventricular stroke work index, and significant increases in arterial blood pressure, central venous pressure, pulmonary artery pressure and systemic vascular resistance index. Dexmedetomidine combined with MK-467 resulted in significant but transient decrease in blood pressure and right ventricular stroke work index.

Conclusion and clinical relevance

Following IV co-administration, MK-467 effectively attenuated dexmedetomidine-induced cardiovascular effects in cats. The drug combination resulted in transient reduction in arterial blood pressure, without causing hypotension.  相似文献   

15.

Objective

To describe a novel ultrasound-guided posterior extraconal block in the dog.

Study design

Prospective experimental cadaveric study.

Animals

A total of 13 Beagle Cross cadaver heads.

Methods

After describing the ultrasound bony landmarks and posterior extraconal local regional technique in one head, 12 heads were used to evaluate the spreading of contrast and evaluate potential complications. A 5–8 MHz microconvex ultrasound probe was positioned caudal to the orbital ligament, with the beam orientated transversely, and then tilted caudally until the orbital fissure was visualized. After identifying the bony structures consistent with the orbital fissure, a needle was advanced using an in-plane technique and 0.5 mL of a 50:50 mixture of iohexol and methylene blue was injected. Computed tomography (CT) and dissection were used to evaluate successful injections and potential complications. The injection was considered successful if radiopaque contrast medium was 5 mm from the orbital fissure. Potential complications were defined as the presence of radiopaque contrast within the globe or the intracalvarial tissues.

Results

The CT images confirmed contrast at the target site in 15/24 (63%) of the injections. Only two injections were found in the temporalis muscle; the rest of the injections were located in the extraconal space. No potential complications such as intracranial spreading of contrast, intravascular or intraocular injection were found.

Conclusions and clinical relevance

The technique can deliver contrast close to the main nerves which provide sensory and motor innervation to the eye. Further studies are needed to evaluate this technique in clinical cases.  相似文献   

16.

Introduction

Transthoracic echocardiography (TTE) is the primary tool for the assessment of cardiac structure and function in dogs but is challenging in English bulldogs due to dorsoventral compression of the thorax, obesity, and narrow intercostal spaces. Multi-detector computed tomography angiography (CTA) may overcome the conformational obstacles of cardiac imaging in this breed.

Animals

Eleven client-owned English bulldogs.

Materials and Methods

Prospective clinical trial with paired analysis of TTE and CTA studies.

Results

Eight of the 25 linear cardiac dimensional measurements were significantly different between TTE and CTA (p<0.033). Intraobserver agreement was strong with average coefficients of variation (CV) of 5.34% for TTE and 2.50% for CTA. Interobserver agreement CV averaged 6.5% for TTE and 8.75% CTA. Ejection fraction, stroke volume, and end-systolic volume were significantly different between modalities (all p<0.002). No significant difference was present between end-diastolic volume for TTE compared with CTA.

Discussion

High-quality cardiac angiographic studies were accomplished using CTA without the use of general anesthesia in English bulldogs. Multi-detector computed tomography angiography and TTE are not interchangeable modalities in the clinical setting.

Conclusion

Multi-detector-CT ECG-gated cardiac angiography is possible in sedated, non-intubated English bulldogs. Differences were found between some cardiac dimensions as measured by TTE in the awake dog and compared with sedated CTA, indicating the two methodologies are not equivalent. Sedated, non-intubated CTA yielded high-quality imaging with strong intraobserver and interobserver measurement repeatability in English bulldogs.  相似文献   

17.

Objective

Measurement of sensory thresholds could represent a complementary tool to behavioural pain scores in cats. The aim of this study was to investigate the feasibility of quantitative sensory testing (QST) with the Electronic von Frey Anesthesiometer (EVF) and von Frey filaments (VFF) in healthy cats, and to assess the limits of agreement (LOA) between the two devices.

Study design

Prospective clinical study.

Animals

A total of 15 client-owned healthy cats.

Methods

Two investigators (A and B) carried out the measurements independently. The EVF and the VFF were applied on the upper lip and at the level of the medial aspect of the stifle. A 1-hour interval was allowed between the sets of measurements taken by investigators A and B; each investigator repeated the entire session of measurements after 24 hours. The LOA between the EVF and the VFF were analysed with the intraclass correlation coefficient (ICC), and with the Bland Altman method.

Results

QST with both the EVF and the VFF was feasible in healthy cats; however, the willingness of the cats to cooperate was negatively affected by the repetition of the measurements on the second day. The presence of the cat owners seemed to facilitate the trial. There was a fair agreement between the EVF and the VFF (ICC = 0.49; 95% confidence interval: 0.13–0.70).

Conclusions

and clinical relevance Our findings indicate that both EVF and VFF may be used for QST in cats. Further trials will be needed to verify the usefulness of QST with EVF and VFF in feline patients suffering from actual chronic pain.  相似文献   

18.

Background

Increased cardiac troponin I (cTnI) concentration has been reported in dogs with atrioventricular (AV) block before and shortly following pacemaker implantation. The role of AV dyssynchrony, age, or concurrent cardiac disease on cTnI concentration remains unknown.

Objectives

To investigate change in cTnI concentration following dual-chamber pacemaker implantation on short- and long-term follow-up and to compare cTnI values to a case-matched control group.

Animals

Thirty-eight client-owned dogs with permanent AV block and 38 matched control dogs.

Methods

Retrospective review of medical records. Pacemaker group consisted of dogs with AV block and dual-chamber pacing. Control group matched the study population in age and cardiac disease. cTnI was compared between pacemaker and control group on short- and long-term follow-up. Different lead types and influence of arrhythmia on cTnI were tested.

Results

cTnI was high at presentation (median 0.66 ng/ml; range 0.03–18.6) and showed a significant reduction over time after pacemaker implantation (p < 0.0001). Median cTnI values were significantly different between pacemaker and control group on short-term (p = 0.0004; 0.11 ng/ml, range 0.03–1.36 versus 0.06 ng/ml, range 0.03–0.46), but not on long-term follow-up (p = 0.0547; 0.14 ng/ml, range 0.03–0.73 versus 0.07 ng/ml, range 0.03–0.46). Lead type and severity of arrhythmia did not show a significant correlation to cTnI concentration.

Conclusions

On long-term follow-up, cTnI remained mildly elevated in some of the pacemaker dogs but was not significantly different to the matched control group.  相似文献   

19.

Objective

To characterize the pharmacokinetics of dexmedetomidine when administered as a short intravenous (IV) infusion to isoflurane-anesthetized rabbits.

Study design

Experimental study.

Animals

A total of six healthy adult female New Zealand White rabbits.

Methods

Rabbits were anesthetized with isoflurane in oxygen. Following determination of isoflurane minimum alveolar concentration (MAC), the anesthetic dose was reduced to 0.7 × MAC, and dexmedetomidine hydrochloride (20 μg kg?1) was infused IV over 5 minutes. Arterial blood samples were obtained immediately before and at 1, 2, 5, 6, 7, 10, 15, 30, 60, 90, 120, 240 and 360 minutes following termination of the infusion. Samples were transferred into tubes containing ethylenediaminetetraacetic acid and centrifuged immediately. The plasma was harvested and stored at –80 °C until analyzed. Concentrations of dexmedetomidine in plasma were determined by liquid chromatography mass spectrometry. Compartment models were fitted to the time and concentration data using nonlinear regression.

Results

A three-compartment model best fit the data set. Median volume of distribution at steady state and terminal half-life were 3169 mL kg?1 (range, 2182–3859 mL kg?1) and 80 minutes (range, 72–88 minutes), respectively.

Conclusions and clinical relevance

The pharmacokinetics of dexmedetomidine in isoflurane-anesthetized, healthy, New Zealand White rabbits were characterized in this study. Data from this study can be used to determine dosing regimens for dexmedetomidine in isoflurane-anesthetized rabbits.  相似文献   

20.

Objective

To describe ultrasound-visualized anatomy and the spread characteristics of a dye injected in the thoracic paravertebral (TPV) space under ultrasound guidance.

Study design

Anatomic cadaver study.

Animals

Seven dog cadavers.

Methods

One cadaver was used to observe, identify, and describe the relevant TPV anatomy. In the remaining six, the left fifth TPV space was randomly assigned to be injected with either a low volume (LV; 0.05 mL kg?1) or high volume (HV; 0.15 mL kg?1) of dye. Subsequently, the contralateral side was injected with the alternative volume. Anatomic dissections were conducted to determine the incidence of complete spinal nerve staining (>1 cm circumferential coverage), number of contiguous spinal nerves dyed and the absence or presence of solution in particular locations.

Results

The ultrasound-visualized anatomy of the TPV space was defined as the intercostal space abaxial to the vertebral body, delimited by the parietal pleura ventrally and the internal intercostal membrane dorsally. The endothoracic fascia divides the paravertebral space into dorsal and ventral compartments. The target nerve was completely dyed in five of six and six of six injections in the LV and HV conditions, respectively. In one LV injection, the nerve was partially dyed. No multisegmental spread affecting contiguous spinal nerves was found in either treatment. Multisegmental spread was found in the ventral compartment of the TPV space, affecting the sympathetic trunk on 3 (0–3) and 3.5 (1–6) vertebral spinal levels in the LV and HV conditions, respectively, but differences between volumes were not significant. No intrapleural, ventral mediastinal or epidural migration was observed.

Conclusions and clinical relevance

Ultrasound-guided TPV block is a potentially reliable technique. The LV appeared sufficient to dye a single spinal nerve and multiple sympathetic trunk vertebral levels. Multiple TPV injections may be needed to provide adequate thoracic analgesia in dogs undergoing thoracic surgery.  相似文献   

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