Veterinary anaesthesia and analgesia最新文献

Objective: To compare the perioperative analgesic effect of lateral versus latero-ventral quadratus lumborum block (QLB) in dogs undergoing laparoscopic ovariectomy.

Study design: Randomized, blinded clinical study.

Animals: A total of 15 client-owned female dogs undergoing laparoscopic ovariectomy.

Methods: Animals were randomly assigned to receive a bilateral QLB, performed with 0.3 mL kg^-1 ropivacaine 0.5%, either with lateral (group L_QLB, n = 7) or latero-ventral approach (group LV_QLB, n = 7). Dogs were premedicated intramuscularly with methadone 0.2 mg kg^-1 and dexmedetomidine 3 μg kg^-1. General anaesthesia was induced intravenously (IV) with propofol and maintained with isoflurane. Cardiovascular and respiratory variables were continuously monitored and recorded every 5 minutes during surgery. Fentanyl 3 μg kg^-1 was administered IV if there was a 20% increase in heart rate and/or mean arterial pressure from previous values recorded 5 minutes before. Meloxicam 0.2 mg kg^-1 was administered IV to all dogs during recovery. The short-form of the Glasgow Composite Pain Scale was used hourly for 8 hours post-QLB. Methadone 0.2 mg kg^-1 was administered IV when pain score was ≥ 6/24. A chi-square test compared the number of dogs requiring intraoperative rescue fentanyl. A Friedman test with a Dunn's post hoc was used to evaluate the trend in postoperative pain scores within each group, and a Mann-Whitney U test compared scores between the groups at each time point; p < 0.05.

Results: Significantly fewer dogs required intraoperative rescue fentanyl in group L_QLB than in group LV_QLB. No dog required postoperative rescue methadone, and there were no significant differences in pain scores.

Conclusions and clinical relevance: Bilateral QLB performed with lateral approach reduced the number of dogs requiring intraoperative rescue analgesia in comparison with the latero-ventral approach. No differences were detected postoperatively, possibly owing to the confounding effects of methadone, dexmedetomidine and meloxicam.

Objective: To determine the pharmacokinetic profile of methadone after intravenous (IV) and subcutaneous (SC) administration in domestic ferrets (Mustela putorius furo).

Study design: Crossover experimental study.

Animals: A group of eight healthy adult ferrets weighing 1.01 ± 0.23 kg (mean ± standard deviation).

Methods: Methadone hydrochloride (0.3 mg kg^-1) was injected IV or SC to each ferret with a 3 week washout period. Blood samples were collected via a jugular catheter before and 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 240, 360 and 480 minutes after drug administration. Liquid chromatography-tandem mass spectrometry was used to determine plasma methadone concentrations. A nonlinear mixed effects model was used to analyze the data.

Results: After IV injection, systemic clearance (Cl_ss) and volume of distribution (Vd_ss) were 78.9 mL min^-1 kg^-1 and 9.8 L kg^-1, respectively. Elimination half-life was 2.0 hours and SC bioavailability was fixed at 1. The maximum observed plasma concentration after SC injection was 92.1 ± 76.8 ng mL^-1. Behavioral changes were observed after both routes.

Conclusions and clinical relevance: The pharmacokinetic profile of IV methadone was characterized by a high Cl_ss and large Vd_ss, with high bioavailability and absorption rate after SC administration. Half-life was short and mean plasma methadone concentrations stayed above the minimum effective concentration (MEC) reported in humans only after SC administration for 5 minutes, but remained above that reported in dogs for 45 minutes following both routes. Further studies investigating the MEC and pharmacodynamics of methadone in ferrets are warranted.

Objective: To evaluate the effects of wrapping the extremities of small dogs with table leg covers to prevent hypothermia during anesthesia.

Study design: Randomized parallel-group study.

Animals: A total of 60 adult dogs with a body mass <15 kg anesthetized for soft tissue surgery.

Methods: Dogs were randomly assigned to one of two groups. The control group received routine intraoperative thermal support, while the limb-wrapping group had their peripheral limbs covered with table leg covers up to the mid-metacarpal/metatarsal region, in addition to routine thermal support. Rectal temperature during anesthesia was recorded and compared between the two groups. Data analyses were performed using Student's t-test for rectal temperature, Fisher's exact test for hypothermia incidence and analysis of covariance for the effect of limb-wrapping while taking other factors into account.

Results: Thirty dogs were included per group. Rectal temperature did not differ between the groups at the time of intubation, but it was significantly higher in the limb-wrapping group (36.7 ± 1.0 °C) than in the control group (35.9 ± 0.8 °C) at the end of surgery (p = 0.003). The mean difference was 0.81 °C (95% confidence interval of mean difference 0.33-1.29 °C). The incidence of hypothermia (<37.0 °C) was significantly lower in the limb-wrapping group than in the control group (19/30 versus 28/30 dogs, respectively; p = 0.010).

Conclusions: For dogs with body masses <15 kg, limb-wrapping with table leg covers slowed the reduction in intraoperative rectal temperature. Limb-wrapping is inexpensive and easy to perform, making it a practical method for minimizing hypothermia during anesthesia in small dogs undergoing soft tissue surgery.

Clinical relevance: Peripheral warming with table leg covers has the potential to reduce hypothermia during soft tissue surgery in small dogs.

Objective: To compare the sensitivity and specificity of pH with multichannel intraluminal impedance (pH-MII), pH-metry (pH) alone and MII alone to direct observation of GOR by endoscopy in anaesthetized dogs.

Study design: A prospective comparative trial in a live canine model.

Animals: A group of 35 (22 females, 13 males) dogs of various breeds. The mean (range) body weight and age were 31.9 (14-40) kg and 5.6 (0.75-12) years, respectively.

Methods: All dogs were premedicated with medetomidine and morphine, anaesthesia was induced with propofol and maintained on isoflurane in oxygen. A monitoring assembly consisting of an endoscopy camera, endotracheal tube and a disposable flexible pH-MII catheter was used to measure oesophageal pH, MII and directly visualize reflux. Visual reflux score was (0-3) and pH was recorded on a data capture sheet. Reflux was considered to have occurred whenever oesophageal pH was < 4.0 or > 7.5, device software analysing MII data detected fluid or a visual reflux score of 2 or 3 were assigned. Receiver operator curves (ROC) analysis was used to determine sensitivity and specificity for each monitoring method to detect GOR.

Results: Endoscopy identified GOR in 20 dogs (57%), pH-MII in 19 dogs (54%), pH alone in 13 dogs (37%) and MII alone in 12 dogs (24%). ROC analysis showed fair accuracy for pH-MII and pH alone, whereas MII demonstrated low accuracy.

Conclusions and clinical relevance: In conclusion, pH-MII is a reliable method for detecting GOR and emerges as a promising tool for future research. Endoscopy is reliable and provides the ability to subjectively quantify the volume of reflux; however, it lacks the ability to discern the pH of refluxate. pH alone misses reflux events with intermediate pH (4.1-7.4). Incorporation of impedance addresses some of the limitations associated with pH alone and enhances diagnostic accuracy.

Objective: To describe an ultrasound-guided suprazygomatic approach to the trigeminal nerve block in cat cadavers.

Study design: Prospective descriptive study.

Animals: Ten feline cadaver heads.

Methods: A 25:75 methylene blue-iopamidol mixture (0.1 mL cm^-1 cranium length) was injected into 10 cadaver heads using an ultrasound-guided suprazygomatic approach. A computed tomography (CT) scan was performed to identify contrast presence at the orbital fissure, foramen rotundum and ovale, followed by anatomical dissection to identify staining of the pterygopalatine fossa (PPF), extraconal retrobulbar area, mandibular and maxillary nerves. Descriptive statistics were used to summarize results.

Results: A total of 20 injections were performed. Of these, 1/20 misinjection occurred and excluded from further reporting. The volume of injectate was 0.9 (0.9-1.1) mL [median (range)]. Staining of the PPF, extraconal space, maxillary and mandibular nerves over more than 6 mm was achieved in 19/19 (100%), 18/19 (95%), 17/19 (89%) and 19/19 (100%) of injections, respectively. CT showed presence of contrast within 5 mm of the orbital fissure, foramen rotundum and ovale in 18/19 (95%), 19/19 (100%) and 19/19 (100%) of the injections, respectively. No intracranial migration was observed.

Conclusions and clinical relevance: This cadaver study illustrates that the suprazygomatic ultrasound-guided trigeminal nerve injection technique can successfully stain the PPF, retrobulbar cone extraconally, mandibular and maxillary nerves. Consequently, this technique has the potential to be used in vivo in cats to desensitize areas innervated by the trigeminal nerve.

Objective: To characterize the correlation, agreement and concordance of cardiac output (CO) measured with transthoracic ultrasound and the correlation and concordance of aortic blood flow (ABF) minute distance (MD) measured by transesophageal Doppler with CO measured by pulmonary artery thermodilution (PATD) in cats.

Study design: Experimental study.

Animals: A group of six healthy male neutered cats, aged 2-8 years and weighing 5.3 ± 0.3 kg.

Methods: Cats were anesthetized with isoflurane in oxygen. CO was measured by PATD (CO_PATD) and transthoracic echocardiography (CO_ECHO). ABF MD was measured using an esophageal Doppler flow probe aligned with descending ABF. All measurements were made under three conditions: dexmedetomidine (20 μg kg^-1) intravenously; atipamezole (200 μg kg^-1) intramuscularly and atropine (20 μg kg^-1) intravenously as needed to achieve a minimum heart rate of 140 beats minute^-1; and dopamine (20 μg kg^-1 minute^-1) intravenously in that order. Correlation between CO_PATD and CO_ECHO, and CO_PATD and Doppler MD was evaluated using repeated measures correlation. Agreement between CO_PATD and CO_ECHO was evaluated using Bland-Altman method. Differences between consecutive pairs of CO measurements were calculated for concordance analysis.

Results: Correlation between CO_PATD and CO_ECHO and between CO_PATD and MD was significant (p < 0.001), with correlation coefficients greater than 0.92. A bias of > 27% and upper limits of agreement of 66% were found between CO_PATD and CO_ECHO. Concordance rate with CO_PATD was 76-80% for CO_ECHO and 72% for MD.

Conclusions and clinical relevance: Echocardiographic methods for the measurement of CO showed poor agreement and concordance with PATD. MD showed poor concordance with PATD. As such, these methods cannot be used as an alternative to PATD nor can they appropriately track changes in CO in anesthetized cats.

Objective: To develop an ultrasound (US)-guided ventral approach to the brachial plexus (BP) and evaluate nerve anatomy and staining in barred owl cadavers.

Study design: Prospective, cadaveric study.

Animals: Eleven adult male and female barred owl cadavers with a body mass of 0.43-0.98 kg.

Methods: Eleven frozen cadavers were thawed for 48 hours, weighed and assigned a body condition score. Ten cadavers were placed in dorsal recumbency with wings abducted. US-guided visualization of the BP was achieved by placing a 13-6 MHz linear probe over the ventral aspect of the scapulohumeral joint, parallel to the sternum. A 22 gauge, 50 mm insulated needle was advanced in-plane in a caudal-to-cranial direction. In each owl, injection targeting one BP was performed with 0.4 mL kg^-1 of a 1:1 0.5% ropivacaine and 1% methylene blue solution. Dissection was performed 15 minutes postinjection. Nerve staining was deemed successful if ≥ 1 cm of circumferential staining was achieved. The eleventh owl cadaver was injected with a 1:1 solution of 1% methylene blue and 74% ioversol contrast into both wings, and computed tomography (CT) was performed just before and 15 minutes after injection.

Results: The BP was clearly identified ultrasonographically in cadavers weighing > 0.5 kg. An injectate volume of 0.4 mL kg^-1 provided complete staining of the BP branches in all cadavers. CT scan revealed no contrast within the coelomic cavity.

Conclusions and clinical relevance: The US-guided BP injection using a ventral approach was easily performed in barred owl cadavers weighing > 0.5 kg. The injection of 0.4 mL kg^-1 of a ropivacaine-dye solution resulted in complete staining of the BP branches in all wings, suggesting that this technique could provide analgesia for structures distal to the scapulohumeral joint. Clinical studies are necessary to confirm the safety and efficacy of this technique in barred owls and other bird species.