Intraperitoneal and incisional ropivacaine did not improve postoperative analgesia after multimodal anaesthesia compared with saline in dogs undergoing ovariohysterectomy.

INTRODUCTION: Intraperitoneal administration of local anaesthetics may reduce postoperative pain after ovariohysterectomy in dogs. The aim of this prospective, randomised, blinded, placebo-controlled clinical trial was to compare postoperative analgesia and opioid requirements after intraperitoneal and incisional administration of ropivacaine versus 0,9 % NaCl (saline). Forty-three client-owned dogs were enrolled in the study and anaesthetised using a standardized protocol that included premedication with acepromazine (0,03-0,05 mg/kg) and dexmedetomidine (0,01 mg/kg) intramuscularly. Anaesthesia was induced with propofol titrated to effect and ketamine (1 mg/kg) intravenously and maintained with isoflurane in oxygen. The analgesic regimen included carprofen (4 mg/kg) subcutaneously and morphine (0,2 mg/kg) intravenously. Depending on group assignment, each dog received either an intraperitoneal and incisional splash with ropivacaine (2 mg/kg and 1 mg/kg, respectively) (group R), or an equal volume of saline (group S). Buprenorphine (0,02 mg/kg) was administered intramuscularly once the uterus was removed. Sedation and pain were assessed 0,5, 1, 2, 4, 6 and 8 hours after extubation using a sedation scale, the short form of the Glasgow Composite Pain Scale (CMPS-SF) and a dynamic interactive visual analogue scale (DIVAS). Postoperatively, buprenorphine (0,01 mg/kg) was administered intravenously if dogs scored 6/24 on CMPS-SF. The ordinal mixed model showed no difference in pain scores between groups. Fisher's exact test showed no significant difference in postoperative buprenorphine requirements between group S (3/22 dogs) and group R (1/21 dogs) at the doses used. In addition, lower sedation scores were associated with higher DIVAS scores. In this multimodal analgesic protocol, ropivacaine could not improve analgesia compared to saline.

INTRODUCTION: L'administration intrapéritonéale d'anesthésiques locaux peut réduire la douleur postopératoire après une ovariohystérectomie chez la chienne. L'objectif de cet essai clinique prospectif, randomisé, en aveugle et contrôlé par placebo était de comparer l'analgésie postopératoire et les besoins en opioïdes après l'administration intrapéritonéale et incisionnelle de ropivacaïne par rapport à du NaCl 0,9 % (sérum physiologique). Quarante-trois chiennes appartenant à des clients ont été enrôlés dans l'étude et anesthésiés selon un protocole standardisé comprenant une prémédication par acépromazine (0,03 - 0,05 mg/kg) et dexmedetomidine (0,01 mg/kg) par voie intramusculaire. L'anesthésie a été induite avec du propofol dosé à l'effet et de la kétamine (1 mg/kg) par voie intraveineuse et maintenue avec de l'isoflurane dans de l'oxygène. Le traitement analgésique comprenait du carprofène (4 mg/kg) par voie sous-cutanée et de la morphine (0,2 mg/kg) par voie intraveineuse. En fonction de son affectation à un groupe, chaque chien a reçu soit une injection intrapéritonéale et incisionnelle de ropivacaïne (2 mg/kg et 1 mg/kg, respectivement) (groupe R), soit un volume égal de solution saline (groupe S). La buprénorphine (0,02 mg/kg) a été administrée par voie intramusculaire après l'ablation de l'utérus. La sédation et la douleur ont été évaluées 0,5, 1, 2, 4, 6 et 8 heures après l'extubation à l'aide d'une échelle de sédation, de la forme courte de l'échelle composite de douleur de Glasgow (CMPS-SF) et d'une échelle visuelle analogique interactive dynamique (DIVAS). En postopératoire, de la buprénorphine (0,01 mg/kg) a été administrée par voie intraveineuse si les chiens obtenaient un score de 6/24 sur l'échelle CMPS-SF. Le modèle mixte ordinal n'a montré aucune différence dans les scores de douleur entre les groupes. Le test exact de Fisher n'a pas montré de différence significative dans les besoins postopératoires en buprénorphine entre le groupe S (3/22 chiens) et le groupe R (1/21 chiens) aux doses utilisées. De plus, des scores de sédation plus faibles étaient associés à des scores DIVAS plus élevés. Dans ce protocole d'analgésie multimodale, la ropivacaïne n'a pas permis d'améliorer l'analgésie par rapport au sérum physiologique.

Endotoxic kidney injury in Beagle dogs assessed by serum creatinine and symmetric dimethylarginine, and urinary neutrophil gelatinase-associated lipocalin and clusterin.

Sepsis of Gram negative bacterial origin results in lipopolysaccharide-induced endotoxemia. This often leads to acute kidney injury (AKI) and its recognition remains a challenge and delays treatment. As renal damage occurs before a rise in serum creatinine is detected, new early biomarkers of kidney injury need to be explored. The aim of this study was to determine changes in serum parameters of renal function and urine biomarkers of renal injury. This was a descriptive study. Endotoxemia was induced intravenously in six anaesthetized Beagles (T1). To achieve normotension, dogs received fluids (T2), followed by a continuous infusion of noradrenaline and dexmedetomidine or 0.9% NaCl (T3). Ten minutes later, the dogs received fluids (T4) and noradrenaline and dexmedetomidine or 0.9% NaCl in a crossover manner (T5). At each timepoint, blood and urine were collected for serum creatinine, urea, symmetric dimethylarginine, urine protein/creatinine (UPC) ratio, urine neutrophil-gelatinase-associated lipocalin (U-NGAL), U-NGAL/creatinine ratio, urine clusterin (U-clusterin) and U-clusterin/creatinine ratio. Data were analyzed using a mixed-effect model taking into account time and stage of veterinary AKI (VAKI). Three of six dogs had a VAKI stage ≥1; one with anuria and elevated creatinine. Serum creatinine (P < 0.001), U-NGAL/creatinine ratio (P = 0.01) and U-clusterin/creatinine ratio increased over time (P < 0.01). The UPC ratio (mean (range) 0.68 (0.35-2.3) versus 0.39 (0.15-0.71) P < 0.01) and U-NGAL (3164 pg/mL (100-147,555) versus 100 (100-14,524), P = 0.01) were higher in VAKI stage ≥1 versus stage 0, respectively. Endotoxemia induced VAKI stage ≥1 in half of the dogs. Repeated measurement of selected parameters could detect AKI early.

Effect of early administration of tranexamic acid on ongoing haemorrhage in dogs with non-surgically treated haemoabdomen.

INTRODUCTION: Tranexamic acid (TXA) is an antifibrinolytic drug used for the prophylaxis and treatment of haemorrhage of various origin. This retrospective study investigated the effect of TXA on ongoing bleeding in dogs with nonsurgically treated haemoabdomen. The study population consisted of 48 dogs treated in the period 2009-2020 at the Small Animal Clinic of the Vetsuisse Faculty of Zurich. Twenty-eight of 48 dogs were treated with 20 mg/kg TXA IV within 3h of diagnosis of haemoabdomen. Dogs treated with and without TXA were monitored over 48 hours for signs of ongoing haemorrhage. Ongoing haemorrhage was defined as an increase in abdominal fluid accumulation, a decrease in haematocrit of >5% over time or need for surgical exploration after at least 12 hours of medical treatment. Transfusion requirements, cumulative amount of fluid therapy, heart rate, respiratory rate, temperature, systolic and mean arterial pressure, estimate of abdominal fluid identified by FAST analysis, venous haematocrit, abdominal haematocrit, serum albumin, serum lactate and thrombocyte count were extracted from patient records at 6, 12, 24 and 48 hours after diagnosis of haemoabdomen. Groups were comparable at presentation, however dogs of the TXA group showed a significantly lower abdominal haematocrit at presentation (37 vs 45%, P=0,034) and a higher fluid accumulation (P=0,019), both persisting over time. None of the outcome parameters for ongoing haemorrhage was significantly different between groups. Transfusion requirement was low and similar in both groups. Of interest, none of the 16 dogs undergoing thromboelastometry showed hyperfibrinolysis at presentation. We conclude that other mechanisms than antifibrinolytic therapy was responsible for cessation of bleeding in the majority of patients.

INTRODUCTION: L'acide tranexamique (TXA) est un médicament anti fibrinolytique utilisé pour la prophylaxie et le traitement des hémorragies d'origines diverses. Cette étude rétrospective a examiné l'effet du TXA sur les saignements en cours chez les chiens présentant un hémoabdomen traité sans chirurgie. La population étudiée était composée de 48 chiens traités entre 2009 et 2020 à la clinique pour petits animaux de la faculté Vetsuisse de Zurich. Vingt-huit des 48 chiens ont été traités avec 20 mg/kg de TXA IV dans les 3 heures suivant le diagnostic de l'hémoabdomen. Les chiens traités avec et sans TXA ont été surveillés pendant 48 heures pour détecter les signes d'hémorragie en cours. L'hémorragie en cours a été définie comme une augmentation de l'accumulation de liquide abdominal, une diminution de l'hématocrite de >5% dans le temps ou la nécessité d'une exploration chirurgicale après au moins 12 heures de traitement médical. Les besoins transfusionnels, la quantité cumulative de traitement liquidien, la fréquence cardiaque, la fréquence respiratoire, la température, la pression artérielle systolique et moyenne, l'estimation du liquide abdominal identifié par l'analyse FAST, l'hématocrite veineux, l'hématocrite abdominal, l'albumine sérique, le lactate sérique et la numération des thrombocytes ont été extraits des dossiers des patients à 6, 12, 24 et 48 heures après le diagnostic d'hémoabdomen. Les groupes étaient comparables à la présentation, mais les chiens du groupe TXA présentaient un hématocrite abdominal significativement plus faible à la présentation (37 vs 45 %, P=0,034) et une accumulation de liquide plus importante (P=0,019), ces deux phénomènes persistant dans le temps. Aucun des paramètres de résultat pour l'hémorragie en cours n'était significativement différent entre les groupes. Les besoins en transfusion étaient faibles et similaires dans les deux groupes. Il est intéressant de noter qu'aucun des 16 chiens soumis à la thromboélastométrie ne montrait d'hyperfibrinolyse à la présentation. Nous concluons que d'autres mécanismes que le traitement anti fibrinolytique étaient responsables de l'arrêt des saignements chez la majorité des patients.

Rotational thromboelastometry (ROTEM) parameters in dogs with haemoperitoneum and their associations with clinical and laboratory signs.

INTRODUCTION: Rotational thromboelastometry (ROTEM) is a viscoelastic coagulation test that allows the evaluation of haemostasis from clot formation to clot dissolution. The aim of this retrospective study was to describe the changes in haemostasis using ROTEM parameters in dogs presenting with spontaneous or traumatic haemoperitoneum and to evaluate any associations between clinical and laboratory parameters at presentation with the ROTEM. We hypothesized that the dogs would show signs of hypocoagulability and hyperfibrinolysis and that these changes would correlate with the degree of hypoperfusion. Clinical records were searched for a period of 5 years for dogs presenting with a haemoperitoneum und for whom a -ROTEM analysis at presentation was carried out. Forty dogs were identified, and various clinical and laboratory parameter (heart rate, blood pressure, blood glucose, lactate, serum albumin concentration, PCV (venous and abdominal), ionized calcium, pH and base excess) were retrieved. The following ROTEM parameters were analysed: extrinsic clotting time (ExTEM CT), clot formation time (ExTEM CFT), clot firmness (ExTEM MCF) and maximum lysis (ExTEM ML), as well as fibrinogen (FibTEM) CT and MCF. Compared to institutional reference intervals, dogs with haemoabdomen showed prolongation of ExTEM and FibTEM CT, ExTEM CFT and 50% were hypocoagulable and 62% thrombocytopenic. No hyperfibrinolysis could be detected. Multiple linear regression models showed an association between decreased base excess, trauma and ROTEM signs for hypocoagulability. Furthermore, age was associated with a stronger fibrin clot. In conclusion, 50% of the dogs presented hypocoagulable and changes in ROTEM parameters are similar to those seen with consumption coagulopathy. Base excess and trauma were associated with hypocoagulability, while increasing age was associated with a stronger fibrin clot.

INTRODUCTION: La thromboélastométrie rotationnelle (ROTEM) est un test de coagulation viscoélastique qui permet d'évaluer l'hémostase depuis la formation du caillot jusqu'à sa dissolution. Le but de cette étude rétrospective était de décrire les changements de l'hémostase à l'aide des paramètres ROTEM chez des chiens présentant un hémopéritoine spontané ou traumatique et d'évaluer d'éventuelles association entre les paramètres cliniques et de laboratoire lors de la présentation avec le ROTEM. Nous avons émis l'hypothèse que les chiens montreraient des signes d'hypocoagulabilité et d'hyperfibrinolyse et que ces changements seraient en corrélation avec le degré d'hypoperfusion. Les dossiers cliniques ont été recherchés surune période de 5 ans pour les chiens présentant un hémopéritoine et pour lesquels une analyse ROTEM à la présentation avait été effectuée. Quarante chiens ont été identifiés et divers paramètres cliniques et de laboratoire (fréquence cardiaque, tension artérielle, glycémie, lactate, concentration d'albumine sérique, PCV (veineux et abdominal), calcium ionisé, pH et excès basique) ont été relevés. Les paramètres ­ROTEM suivants ont été analysés: temps de coagulation extrinsèque (ExTEM CT), temps de formation de caillot (ExTEM CFT), fermeté du caillot (ExTEM MCF) et lyse maximale (ExTEM ML), ainsi que fibrinogène ­(FibTEM) CT et MCF. Par rapport aux intervalles de référence admis, les chiens avec hémoabdomen ont montré une prolongation d'ExTEM et FibTEM CT, ExTEM CFT, 50% étaient hypocoagulables et 62% thrombocytopéniques. Aucune hyperfibrinolyse n'a pu être détectée. Plusieurs modèles de régression linéaire ont montré une association entre une diminution de l'excès basique, des traumatismes et des signes ROTEM d'hypocoagulabilité. De plus, l'âge était associé à un caillot de fibrine plus fort. En conclusion, 50% des chiens présentaient une hypocoagulabilité et les changements dans les paramètres ROTEM sont similaires à ceux observés lors de coagulopathie de consommation. Un excès basique et un traumatisme étaient associés à une hypocoagulabilité, tandis qu'une augmentation de l'âge était associée à un caillot de fibrine plus fort.

Effect of 50 mg/kg intravenous tranexamic acid on coagulation assessed by rotational thromboelastometry (ROTEM) in healthy Beagle dogs.

INTRODUCTION: In people, the antifibrinolytic drug tranexamic acid reduces bleeding and the need for blood products with both normal and exaggerated fibrinolysis without increasing the number of thromboembolic events. In dogs, in addition to prevention and treatment of bleeding, higher doses of tranexamic acid can be used to induce vomiting. The objective of this study was to evaluate the effect of a high dose of tranexamic acid on the coagulation of healthy Beagle dogs. A prospective trial was conducted in eight healthy Beagles receiving tranexamic acid for a concurrent trial evaluating different antiemetics. Rotational thromboelastometry (ROTEM) analysis (EXTEM, APTEM, FIBTEM, INTEM) was performed before and 30 minutes after intravenous administration of 50 mg/kg tranexamic acid. ROTEM parameters before and after tranexamic acid administration and between EXTEM and APTEM were compared with Wilcoxon matched-pairs signed rank test and data is presented as median (range). After tranexamic acid administration, FIBTEM clotting time became significantly shorter (p=0.03) from 37 s (28-124 s) to 33 s (27-40 s) and INTEM clot formation time significantly decreased (p=0.02) from 82 s (47-132 s) to 60 s (43-107 s). After tranexamic acid APTEM MCF was significantly weaker (p=0.01) with 45 mm (30-63 mm) than EXTEM MCF with 55 mm (43-69 mm) and than APTEM MCF before tranexamic acid with 55 mm (43-69 mm) (p=0.02). All other analysed parameters including maximum lysis did not change after administration of tranexamic acid. The administration of 50 mg/kg intravenous tranexamic acid resulted in small changes in ROTEM profiles without inducing a hypercoagulable clot. In conclusion, tranexamic acid can safely be administered to healthy dogs with normal coagulation profiles. As an additional finding, APTEM parameters measured in the current study do not support the use of this test in dogs.

INTRODUCTION: Chez l'homme présentant une fibrinolyse normale et exagérée, l'acide tranexamique, un agent antifibrinolytique, réduit les saignements et le besoin de produits sanguins sans augmenter le nombre d'événements thromboemboliques. Chez les chiens, en plus de la prévention et du traitement des saignements, des doses plus élevées d'acide tranexamique peuvent être utilisées pour provoquer des vomissements. L'objectif de cette étude était d'évaluer l'effet d'une dose élevée d'acide tranexamique sur la coagulation de chiens Beagle en bonne santé. Un essai prospectif a été mené chez huit Beagles en bonne santé recevant de l'acide tranexamique dans le cadre d'un essai simultané évaluant différents antiémétiques. Une analyse de la thromboélastométrie rotationnelle (ROTEM) (EXTEM, APTEM, FIBTEM, INTEM) a été réalisée avant et 30 minutes après l'administration intraveineuse de 50 mg/kg d'acide tranexamique. Les paramètres ROTEM avant et après l'administration d'acide tranexamique et entre EXTEM et APTEM ont été comparés au test de rang de Wilcoxon à paires appariées et les données sont présentées sous forme de médiane. Après administration de l'acide tranexamique, le temps de coagulation de FIBTEM est devenu significativement plus court (p = 0,03) de 37 s (28-124 s) à 33 s (27-40 s) et le temps de formation du caillot INTEM a été significativement réduit (p = 0,02) de 82 s (47-132 s) à 60 s (43-107 s). Après l'acide tranexamique, APTEM MCF était significativement plus faible (p = 0,01) avec 45 mm (30-63 mm) que EXTEM MCF avec 55 mm (43-69 mm) et qu'APTEM MCF avant l'acide tranexamique avec 55 mm (43-69 mm) (p = 0,02). Tous les autres paramètres analysés, y compris la lyse maximale, n'ont pas changé après l'administration d'acide tranexamique. L'administration de 50 mg/kg d'acide tranexamique par voie intraveineuse a entraîné de légers changements dans les profils ROTEM sans induire de caillot hypercoagulable. En conclusion, l'acide tranexamique peut être administré en toute sécurité à des chiens en bonne santé présentant des profils de coagulation normaux. Autre constatation supplémentaire, les paramètres APTEM mesurés dans la présente étude n'appuient pas l'utilisation de ce test chez le chien.

Characteristics of hyperfibrinolysis in dogs and cats demonstrated by rotational thromboelastometry (ROTEM).

Hyperfibrinolysis (HFL) is a pathophysiological mechanism that has not been described in dogs or cats extensively. The aim of this study was to describe rotational thromboelastometry (ROTEM) parameters and underlying diagnosis in dogs and cats with HFL and evaluate association with bleeding diathesis. The ROTEM database was retrospectively searched for EXTEM (ROTEM activated with proprietary tissue factor) tracings with maximum lysis at 60min ≥15%. Concurrent ROTEM and plasma coagulation tests, thrombocyte number, diagnosis and survival to hospital discharge were extracted from medical records. Analysis of differences between dogs and cats and of factors associated with bleeding, fulminant HFL (clot breakdown within 30min) and survival to hospital discharge were performed. Hyperfibrinolysis was detected in eight cats presenting with haemoabdomen or haemothorax (n=4/8, 50%) and trauma (n=3/8, 38%) and in 36 dogs with angiostrongylosis (n=12, 33%), neoplasia (n=7, 19%), liver disease (n=4, 11%) and others including apparently healthy dogs (n=3, 8%). Hyperfibrinolysis was associated with prolonged EXTEM and APTEM (EXTEM with added apoprotein for inhibition of HFL) clotting time and decreased FIBTEM (EXTEM with added cytochalasin D for inhibition of thrombocytes) maximum clot firmness (MCF) in dogs and cats and with decreased EXTEM MCF in dogs. Bleeding dogs had significantly hypocoagulable EXTEM tracings. Fulminant HFL was associated with severe hypofibrinogenaemia in dogs (P=0.005) and was not associated with survival to hospital discharge. Evidence of HFL was demonstrated in dogs and cats with bleeding, trauma, parasitic and neoplastic disease. HFL is associated with late and weak clot formation.

Determination of reference intervals and comparison of venous blood gas parameters using a standard and nonstandard collection method in 51 dogs.

INTRODUCTION: The aim of this study was to determine reference intervals (RI) for venous blood parameters determined with the RAPIDPoint 500 (RP500) blood gas analyzer using blood gas syringes (BGS) and to determine whether immediate analysis of venous blood collected into lithium heparin (LH) tubes can replace anaerobic blood sampling into BGS. The null hypothesis was that canine venous blood samples collected in BGS and in LH tubes are comparable. Jugular blood was collected from 51 healthy dogs into a BGS and a LH tube. The BGS was immediately analyzed followed by the LH tube. The RI were calculated from BGS results. The BGS and LH tubes results were compared using paired t-test or Wilcoxon matched-pairs signed-rank test and Bland-Altman analysis. To assess clinical relevance, the bias between BGS and LH tubes was compared with the allowable total error (TEa). Values derived from LH tubes showed no significant difference for standard bicarbonate (HCO3std), whole blood base excess (BE B), Na, K, Cl, glucose and hemoglobin (tHb). The pH, partial pressure of carbon dioxide and oxygen, actual bicarbonate, extracellular base excess, ionized Ca, anion gap and lactate were significantly (p.

INTRODUCTION: Le but de la présente étude était de déterminer l'intervalle de référence (RI) de l'analyseur de gaz du sang RAPIDPoint 500 (RP500) pour du sang veineux prélevé dans des seringues pour gaz du sang (BGS) ainsi que de voir si une analyse immédiate du sang collecté dans des tubes à l'héparine de lithium (LH) pouvait remplacer la collecte anaérobe dans des seringues BGS. L'hypothèse était que les échantillons sanguins dans les seringues BGS et dans les tubes LH sont comparables. On a prélevé du sang de la veine jugulaire sur BGS et LH chez 51 chiens en bonne santé, on l'a analysé immédiatement avec l'analyseur RP500 et on a calculé les intervalles de référence pour les résultats des prélèvements sur BGS. Les résultats des prélèvements sur BGS et sur LH ont été comparés au moyen de t-test appariés ou d'un test de Wilcoxon signé ainsi que par une analyse de Bland-Altman. Pour juger de la signification clinique, on a comparé le biais entre BGS et LH avec une erreur globale admissible (TEa). Il n'y avait pas de différence significative entre BGS et LH en ce qui concerne le bicarbonate standard, l'excès basique du sang total, le sodium, le potassium, le glucose et l'hémoglobine. Le pH, les pressions partielles de gaz carbonique et d'oxygène, le bicarbonate effectif, l'excès basique extracellulaire, le calcium ionisé, le trou anionique et le lactate étaient significativement (p.

Hyperfibrinolysis and Hypofibrinogenemia Diagnosed With Rotational Thromboelastometry in Dogs Naturally Infected With Angiostrongylus vasorum.

BACKGROUND: The pathomechanism of Angiostrongylus vasorum infection-associated bleeding diathesis in dogs is not fully understood. OBJECTIVE: To describe rotational thromboelastometry (ROTEM) parameters in dogs naturally infected with A. vasorum and to compare ROTEM parameters between infected dogs with and without clinical signs of bleeding. ANIMALS: A total of 21 dogs presented between 2013 and 2016. METHODS: Dogs with A. vasorum infection and ROTEM evaluation were retrospectively identified. Thrombocyte counts, ROTEM parameters, clinical signs of bleeding, therapy, and survival to discharge were retrospectively retrieved from patient records and compared between dogs with and without clinical signs of bleeding. RESULTS: Evaluation by ROTEM showed hyperfibrinolysis in 8 of 12 (67%; 95% CI, 40-86%) dogs with and 1 of 9 (11%; 95% CI, 2-44%) dogs without clinical signs of bleeding (P = .016). Hyperfibrinolysis was associated with severe hypofibrinogenemia in 6 of 10 (60%; 95% CI, 31-83%) of the cases. Hyperfibrinolysis decreased or resolved after treatment with 10-80 mg/kg tranexamic acid. Fresh frozen plasma (range, 14-60 mL/kg) normalized follow-up fibrinogen function ROTEM (FIBTEM) maximal clot firmness in 6 of 8 dogs (75%; 95% CI, 41-93%). Survival to discharge was 67% (14/21 dogs; 95% CI, 46-83%) and was not different between dogs with and without clinical signs of bleeding (P = .379). CONCLUSION AND CLINICAL IMPORTANCE: Hyperfibrinolysis and hypofibrinogenemia were identified as an important pathomechanism in angiostrongylosis-associated bleeding in dogs. Hyperfibrinolysis and hypofibrinogenemia were normalized by treatment with tranexamic acid and plasma transfusions, respectively.

Femoral and sciatic nerve blockades and incision site infiltration in rabbits undergoing stifle joint arthrotomy.

This study was designed to determine whether perineural injections of local anaesthetics decreases intraoperative nociception and improves postoperative analgesia in New Zealand White rabbits undergoing experimental stifle arthrotomy. All animals were anaesthetized using isoflurane and received morphine intramuscularly. The sciatic and femoral nerves of the leg to be operated on were located using a nerve stimulator (1 Hz, 0.5 mA). Rabbits were assigned to a treatment group (LB; n = 12) or a placebo group (P; n = 12) in a randomized blinded fashion. Group LB received lidocaine 2% (1 mg/kg) combined with bupivacaine 0.5% (0.25 mg/kg) injections around the sciatic and femoral nerves (0.1 mL/kg total volume per site) and subcutaneous infiltration of the incision site with lidocaine 1% (1.25 mg/kg). Group P received the same volume of 0.9% NaCl. Rabbits in group P required higher doses of intraoperative fentanyl and propofol to reduce heart rate and suppress increase in systolic blood pressure, and maintain an adequate anaesthetic plane. Interventional analgesia (buprenorphine and carprofen) was required significantly earlier in rabbits in group P (2 and 6 h after the first nerve blockade, respectively) based on assessment of their pain-related behaviour and range of motion. Using a visual analogue scale (0 mm= no pain to 100 mm= maximal possible pain), rabbits in group LB were judged to show significantly less pain compared with rabbits in group P (14 ± 10 mm and 37 ± 25 mm, respectively) 2 h after nerve blockade. In conclusion, this technique of perineural analgesia combined with incision site infiltration reduced intraoperative fentanyl requirements and improved postoperative analgesia in rabbits.

[Bupivacaine toxicity and propofol anesthesia : animal study on intravascular bupivacaine injection]. / Bupivacaintoxizität und Propofolanästhesie : Tierstudie zur intravasalen Bupivacaininjektion.

BACKGROUND: Several reports have confirmed the efficacy of Intralipid® (containing soya bean oil, egg phospholipids, glycerin and water) in the therapy of systemic local anesthetic intoxication. Pretreatment with Intralipid® shifted the dose-response to bupivacaine-induced asystole in rats. Whether intravenous anesthesia with propofol in the widely used medium chain triglyceride lipid emulsion increases the therapeutic range of systemically administered bupivacaine or not is unknown and was investigated in this study. METHODS: A total of 30 piglets aged 2-6 weeks and weighing 4.5-6.5 kg were randomized into 2 groups and anesthetized with sevoflurane (group S) alone or with propofol 10 mg/kg body weight (BW)/h plus sevoflurane (group PS). After 60 min of steady state anesthesia arterial blood was sampled for assessment of blood gases, acid-base state and triglyceride plasma concentrations. Thereafter bupivacaine 0.125% was continuously infused by an infusion syringe pump through a central venous line at a rate of 4 mg/kg BW/min until invasively measured mean arterial pressure (MAP) was reduced by 50% of initial value. The bupivacaine infusion was stopped, blood for assessment of bupivacaine plasma concentration was drawn and the spontaneous hemodynamic course was observed. Resuscitation was not attempted. Results are presented as median and range. The Mann-Whitney U-test was used to assess differences between the two groups for triglyceride as well as for bupivacaine plasma concentrations measured at MAP 50%. A p-value≤0.05 was considered to be significant. RESULTS: Baseline conditions (arterial blood pH, plasma protein and triglyceride plasma concentrations) did not differ significantly between the two groups. After 1 h of anesthesia, triglyceride plasma concentrations were significantly increased in group PS (median 0.69 mmol/l) compared to the corresponding baseline values (median 0.14 mmol/l; p<0.001) and to the 1 h values of group S (median 0.16 mmol/l; p<0.001). The total amount of bupivacaine administered was 9 mg/kg BW in both groups (6-13 mg/kg BW in group S, 5-13 mg/kg BW in group PS). Resulting bupivacaine plasma concentrations were 180 µmol/l (83-686 µmol/l) in group S and 185 µmol/l (130-465 µmol/l) in group PS. However, the total amount of bupivacaine administered and bupivacaine plasma concentrations at MAP 50% did not reveal statistically significant differences between the two groups but a huge variability of both parameters within each group was observed. None of the 30 piglets spontaneously recovered and they died from pulseless electrical activity or from asystolic cardiac arrest. The time from MAP 50% until cardiac arrest demonstrated a large variability but did not reveal significant differences between the two groups. The time to cardiac arrest was similar in both groups. CONCLUSION: Medium/long chain triglyceride lipid emulsion (50:50) as widely used in propofol solutions did not increase therapeutic safety in cases of intravascular bupivacaine administration in this piglet model.

Enhanced creaming of milk fat globules in milk emulsions by the application of ultrasound and detection by means of optical methods.

The effects of application of ultrasonic waves to recombined milk emulsions (3.5% fat, 7% total solids) and raw milk on fat destabilization and creaming were examined. Coarse and fine recombined emulsions (D[4,3]=9.3 µm and 2.7 µm, respectively) and raw milk (D[4,3]=4.9 µm) were subjected to ultrasound for 5 min at 35°C and 400 kHz or 1.6 MHz (using a single transducer) or 400 kHz (where the emulsion was sandwiched between two transducers). Creaming, as calculated from Turbiscan measurements, was more evident in the coarse recombined emulsion and raw milk compared to that of the recombined fine emulsion. Micrographs confirmed that there was flocculation and coalescence in creamed layer of emulsion. Coalescence was confirmed by particle size measurement. These results imply that ultrasound has potential to pre-dispose fat particles in milk emulsions to creaming in standing wave systems and in systems with inhomogeneous sound distributions.

Electrocardiographic changes during continuous intravenous application of bupivacaine in neonatal pigs.

BACKGROUND: It is controversial as to whether T-wave elevation is caused by local anaesthetics, epinephrine, or their combination. It has been shown that T-elevation after intravascular injection of a small bupivacaine test dose is caused by epinephrine and not by bupivacaine. The aim of this study was to investigate ECG changes with higher doses of i.v. bupivacaine. METHODS: Thirty neonatal pigs were anaesthetized with sevoflurane and their tracheas intubated and artificially ventilated. Under steady-state conditions, bupivacaine was continuously infused (flow rate 3.2 ml kg(-1) min(-1)) by a syringe infusion pump through a central venous catheter. Group 1 received bupivacaine 0.125%, Group 2 bupivacaine 0.5%. The ECG was continuously printed and subsequently analysed for alterations in heart rate, ventricular de- and repolarization, and arrhythmias at 1.25, 2.5, and 5 mg kg(-1) bupivacaine infused. RESULTS: Sinus rhythm persisted in all pigs. Heart rate decreased progressively in both groups, but this was significantly more pronounced in Group 1. T-wave elevation occurred in 40% and 0% (Groups 1 and 2) at 1.25 mg kg(-1), in 80% and 0% at 2.5 mg kg(-1), and in 93% and 80% at 5 mg kg(-1) bupivacaine infused. There were significant differences between the two groups at 1.25 and 2.5 mg kg(-1) infused. CONCLUSIONS: Higher doses of i.v. infused bupivacaine can cause T-elevation. With slower injection technique, T-elevation can already be detected at lower bupivacaine doses administered.

Electrocardiographic alterations during intravascular application of three different test doses of bupivacaine and epinephrine: experimental study in neonatal pigs.

BACKGROUND: Origin of electrocardiographic (ECG) alterations during intravascular injection of local anaesthetic solutions is controversial. The aim of this study was to elucidate whether epinephrine, bupivacaine or their combination is responsible for ECG alteration. METHODS: Forty-five piglets were randomized into three groups. After induction of general anaesthesia using sevoflurane and peripheral venous cannulation, the trachea was intubated, the lungs were artificially ventilated, and anaesthesia was maintained by sevoflurane. Under steady state 0.2 ml kg(-1) and after 10 min 0.4 ml kg(-1) of one of the following three test solutions was administered i.v.: bupivacaine 0.125% (Group 1), bupivacaine 0.125%+epinephrine 1:200 000 (Group 2), and plain epinephrine 1:200,000 (Group 3). The ECG was analysed for alterations in heart rate and T-elevation. RESULTS: After injection of 0.2 or 0.4 ml kg(-1) test solution, an increase in heart rate of at least 10% was found in none of Group 1 and in all of Groups 2 and 3. After application of 0.2 ml kg(-1) test solution, T-elevation was found in 7% of Group 1 and in 93% of Groups 2 and 3. The injection of 0.4 ml kg(-1) revealed a T-elevation in 27%, 100%, and 100%, respectively, in Groups 1, 2, and 3. CONCLUSIONS: This animal model demonstrated that increases in heart rate and T-elevation in the ECG during i.v. application of a common test dose (0.2 ml kg(-1)) of bupivacaine are caused by epinephrine addition. Whether higher doses of bupivacaine alone can cause similar ECG changes or not requires further studies.

Respiratory and cardiovascular effects of doxapram and theophylline for the treatment of asphyxia in neonatal calves.

Respiratory stimulants are widely used in asphyxic neonatal calves despite a lack of data about their effectiveness and indications of possible side effects. The effect of doxapram and theophylline on respiratory, cardiovascular, and acid-base variables was investigated in 10 healthy neonatal calves (Bos Taurus). A venous, a peripheral arterial, and a pulmonary arterial catheter were placed, and central venous, pulmonary, and systemic blood pressures and cardiac output were measured using thermodilution technique. Doxapram, but not theophylline, led to an immediate increase in respiratory rate (P

Cardiopulmonary effects of dexmedetomidine in goats and sheep anaesthetised with sevoflurane.

In sheep, alpha(2)-agonists can induce severe hypoxaemia. In goats, reports on changes in oxygenation are inconsistent. The aim of this study was to compare the cardiopulmonary effects of dexmedetomidine in six goats and four sheep anaesthetised with sevoflurane and maintained at approximately 1 minimal alveolar concentration. The animals were ventilated mechanically and held in an upright position to minimise the influence of positioning on pulmonary function. After baseline cardiopulmonary measures, 2 microg/kg dexmedetomidine was injected intravenously over one minute, and measurements were made for 120 minutes. In both species, respiratory resistance, alveolar dead space and shunt fraction increased and thoracic compliance decreased significantly; arterial, pulmonary arterial, pulmonary capillary wedge and central venous pressures increased and heart rate and cardiac output decreased significantly. Arterial oxygen tension decreased significantly, with no significant difference between the goats and sheep. Wide interindividual differences were observed in both the goats (mean [sd] 144 [149.1] mmHg, range 54.8 to 443.7 mmHg) and sheep (mean [sd] 129.8 [132.1] mmHg, range 33.7 to 352.8 mmHg), but the cardiovascular and respiratory changes were similar in the two species.

Changes in subchondral bone in cartilage resurfacing--an experimental study in sheep using different types of osteochondral grafts.

OBJECTIVE: This article addresses the subchondral bone integrity in cartilage resurfacing by comparing fresh, untreated auto-, xeno-, and photooxidized osteochondral allo- and xenografts. Photooxidation was expected to improve mechanical stability of the osteochondral grafts through an improved linkage of the collagen fibers within the bone matrix. DESIGN: Untreated auto- and xenografts and with photooxidation pretreated allo- and xenografts were surgically implanted in femoral condyles of sheep (n=40). After 2, 6, 12 and 18 months results were evaluated histologically using non-decalcified bone embedded in acrylic resin. Qualitative evaluation was performed with emphasis on bone matrix, biomechanical stability of graft anchorage, formation of cystic lesions, and bone resorption and formation. Quantitative evaluation of the total subchondral bone area was conducted histomorphometrically. Statistical analysis (factorial ANOVA test) was used to compare differences between groups with respect to the percentage of bone matrix and fibrous tissue per section. RESULTS: Subchondral bone resorption was fastest in untreated, fresh autografts, followed by photooxidized allografts, untreated, fresh xenografts and last pretreated photooxidized xenografts. Cystic lesions were seen in all types of grafts, but were most pronounced at 6 months in autografts and least in photooxidized grafts. Cyst-like lesions had subsided substantially in the untreated auto- and photooxidized xenografts, if no graft dislocation occurred during the healing period. Mononuclear cell infiltration and an increase in the presence of multinuclear cells were observed at 2 months, mostly in untreated autografts, followed by photooxidized allo- and untreated xenografts. They were much higher in numbers compared to photooxidized grafts, at least in the early specimens at 2 months. Graft stability was linked to the rate of bone resorption. CONCLUSION: Substantial resorption of the subchondral bone, involving the development of cyst-like lesions, lead to dislocation and finally to cartilage matrix degradation of the grafts. The process of photooxidation decreased the speed of bone resorption in osteochondral grafts and, thus, improved graft stability and cartilage survival. These results suggest that the remodeling of the subchondral bone of the host and the graft within the first 6 months is an important factor in graft stability and overall results of cartilage resurfacing.

Clinical comparison of preanaesthetic intramuscular medetomidine and dexmedetomidine in domestic sheep.

Medetomidine and its active d-enantiomer, dexmedetomidine, are highly selective alpha-2 agonists with potent sedative, anaesthetic-sparing and analgesic effects. These properties make them an ideal pre-anaesthetic medication for noxious surgical procedures. However, sheep can develop adverse hypoxaemic effects after intravenous alpha-2 agonists. Objective of the present study was to compare intramuscular injection of medetomidine or dexmedetomidine at equipotent doses as preanaesthetic medication prior to isoflurane anaesthesia in sheep. Nineteen healthy, adult, non-pregnant, female sheep of various breeds were used. The study was carried out as a randomised, blind trial. Group A received 15 micrograms/kg bwt dexmedetomidine and group B received 30 micrograms/kg bwt medetomidine intramuscularly (i.m.) 30 minutes prior to induction of anaesthesia. Anaesthesia was induced with ketamine (2.0 mg/kg bwt i.v.) and maintained with isoflurane in 100% oxygen. End expired anaesthetic concentration (FEiso), respiratory frequency (fR), direct arterial blood pressures and heart rates (HR) were measured. Arterial blood samples were taken at intervals. Data were averaged over time (sum of measurements/number of measurements) and tested for differences between groups by independent t-tests, and ANOVA for repeated measures followed by Bonferroni corrected t-tests. There were no differences in demographic data between the groups. Duration of anaesthesia [A: 170 (42) minutes, B: 144 (33) minutes] and duration of surgery [A: 92 (32) minutes, B: 85 (31) minutes] were similar in both groups. Average FEiso concentrations required to maintain a surgical plane of anaesthesia were not significantly different between groups [A: 0.82 (0.14)%; B: 1.00 (0.25)%]. Mean average fR, did not differ between groups [A: 31 (14), B: 37 (15)]. Heart rates were significantly lower in group B over the course of the anaesthesia. Mean arterial blood pressures (MAP) were not significantly different between the groups. The PaO2 was less variable in group A than in group B. Individual minimum values were 19.1 kPa and 7.9 kPa in group A and B, respectively. There were no significant differences in PaCO2 and paH between the groups and over time. In conclusion, intramuscular application of dexmedetomidine at 15 micrograms/kg bwt and medetomidine at 30 micrograms/kg bwt prior to isoflurane anaesthesia induced similar changes in clinically monitored cardiorespiratory parameters. The observed differences (heart rates, PaO2) between dexmedetomidine and medetomidine at the chosen dose relationship can be considered clinically not significant. At the chosen dose rates individual animals responded with a transient drop in blood oxygenation, therefore careful monitoring is required. In addition, in compromised sheep medetomidine and dexmedetomidine should be used carefully.