Evaluation of the agreement between lingual and thoracic limb noninvasive blood pressure with invasive blood pressure measurements in anaesthetized horses.

OBJECTIVE: To evaluate the agreement between noninvasive arterial blood pressure (NIBP) measured from the tongue and thoracic limb with invasive blood pressure (IBP), and to compare NIBP measured from the tongue and thoracic limb in anaesthetized horses. STUDY DESIGN: Prospective clinical study. ANIMALS: A group of eight client-owned healthy horses anaesthetized for scheduled procedures, American Society of Anesthesiologists classification I-II, weighing (mean ± standard deviation) 498 ± 91 kg and aged 7.8 ± 6.75 years. METHODS: Animals were premedicated with intravenous (IV) romifidine (0.04-0.08 mg kg-1) and methadone (0.1 mg kg-1). General anaesthesia was induced IV with ketamine (2.5 mg kg-1) and midazolam (0.05 mg kg-1) and maintained with isoflurane. The facial artery was catheterized for IBP measurements. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded from the NIBPtongue, NIBPlimb and IBP every 20 minutes during the procedure. Agreement between NIBP and IBP was evaluated based on the American College of Veterinary Internal Medicine criteria and American Association for Medical Instrumentation criteria using the Bland-Altman method. RESULTS: The mean bias and precision between IBP and NIBP measured from the tongue met the standards for all pressure ranges (< 10 mmHg and < 15 mmHg, respectively). NIBP measurements from the tongue and thoracic limb tended to underestimate IBP measurements. During hypotension, MAPtongue and DAPtongue overestimated IBP, but both precision and accuracy met the criteria. The overall accuracy and precision of NIBPlimb was poorer than NIBPtongue. The percentage of NIBPtongue that differed from IBP by < 10 mmHg was higher than that recorded with NIBPlimb for SAP (46% versus 25%), MAP (77% versus 28%) and DAP (79% versus 19%). CONCLUSIONS AND CLINICAL RELEVANCE: The tongue is a clinically suitable alternative for assessing arterial blood pressure compared with the thoracic limb and can reliably detect hypotension in healthy anaesthetized horses.

The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses.

OBJECTIVE: To investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses. STUDY DESIGN: Retrospective, single-centre study. ANIMALS: A sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021. METHODS: Horses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recoveries were divided into 'good' and 'bad' based on the available recovery scores. Influence of hypoxaemia [PaO2 < 60 mmHg (7.99 kPa)], hypotension (mean arterial pressure < 70 mmHg for at least 15 minutes) and hypercapnia [PaCO2 > 60 mmHg (7.99 kPa)], anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of procedure, emergency or nonemergency, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery on the assigned recovery score (good/bad) were investigated using generalized linear regression analysis (p < 0.05). RESULTS: Hypoxaemia and prolonged duration of anaesthesia were significantly associated with a bad recovery score. No other factors had a significant influence on recovery quality. CONCLUSION AND CLINICAL RELEVANCE: Hypoxaemia and prolonged anaesthesia duration have a negative effect on quality of anaesthetic recovery in horses. Clinically, this highlights the importance of keeping anaesthetic time as short as possible and to monitor oxygenation and treat hypoxaemia as soon as possible.

The analgesic effects of magnesium in veterinary patients: a qualitative evidence synthesis.

OBJECTIVE: To perform a qualitative evaluation of the analgesic effects of magnesium in domestic animals, including its anaesthetic sparing effects. STUDY DESIGN: All database searches were made using PubMed and Google Scholar. Studies published after 1990, evaluating the use of magnesium and reporting information on analgesia, in dogs, cats, horses, cows, goats and sheep were selected (last search in August 2023). A reference check in the selected papers was performed to identify any study which was omitted. The CERQual (Confidence in Evidence from Reviews of Qualitative research) approach was used to assess confidence and analyse the evidence. RESULTS: A total of 20 studies relevant to the analgesic effects of magnesium in veterinary patients and two reviews were included. All were published after 2006. Of the 20, five studies provided information about analgesia in the postoperative period in dogs with heterogenous results. Magnesium added epidurally increased the duration of the sensory block in several species. Motor block was also observed when added to spinal analgesia. Results regarding volatile agents sparing effect were conflicting. Occasional moderate adverse effects were reported in dogs, such as nausea and vomiting, when administered as a bolus in conscious animals, and hypotension when administered intraperitoneally. Collapse was reported in horses after epidural administration. CONCLUSIONS AND CLINICAL RELEVANCE: The evidence of an analgesic effect of magnesium in veterinary patients remains scarce considering the paucity and low quality of published data. Further research may be helpful to establish the efficacy and indications of magnesium in multimodal analgesia in animals.

Comparison between continuous rate infusion and target-controlled infusion of propofol in dogs: a randomized clinical trial.

OBJECTIVE: To compare a propofol continuous rate infusion (CRI) with a target-controlled infusion (TCI) in dogs. STUDY DESIGN: Randomized prospective double-blinded clinical study. ANIMALS: A total of 38 healthy client-owned dogs. METHODS: Dogs premedicated intramuscularly with acepromazine (0.03 mg kg-1) and an opioid (pethidine 3 mg kg-1, morphine 0.2 mg kg-1 or methadone 0.2 mg kg-1) were allocated to P-CRI group (propofol 4 mg kg-1 intravenously followed by CRI at 0.2 mg kg-1 minute-1), or P-TCI group [propofol predicted plasma concentration (Cp) of 3.5 µg mL-1 for induction and maintenance of anaesthesia via TCI]. Plane of anaesthesia, heart rate, respiratory rate, invasive blood pressure, oxygen haemoglobin saturation, end-tidal carbon dioxide and body temperature were monitored by an anaesthetist blinded to the group. Numerical data were analysed by unpaired t test or Mann-Whitney U test, one-way analysis of variance and Dunnett's post hoc test. Categorical data were analysed with Fisher's exact test. Significance was set for p < 0.005. RESULTS: Overall, propofol induced a significant incidence of relative hypotension (mean arterial pressure 20% below baseline, 45%), apnoea (71%) and haemoglobin desaturation (65%) at induction of anaesthesia, with a higher incidence of hypotension and apnoea in the P-CRI than P-TCI group (68% versus 21%, p = 0.008; 84% versus 58%, p = 0.0151, respectively). Propofol Cp was significantly higher at intubation in the P-CRI than P-TCI group (4.83 versus 3.5 µg mL-1, p < 0.0001), but decreased during infusion, while Cp remained steady in the P-TCI group. Total propofol administered was similar between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Both techniques provided a smooth induction of anaesthesia but caused a high incidence of side effects. Titration of anaesthesia with TCI caused fewer fluctuations in Cp and lower risk of hypotension compared with CRI.

Evaluation of urine specific gravity as a predictor of hypotension during anaesthesia in healthy dogs premedicated with dexmedetomidine.

OBJECTIVE: To investigate the relationship between urine specific gravity (USG) and the risk of arterial hypotension during general anaesthesia (GA) in healthy dogs premedicated with dexmedetomidine and methadone. STUDY DESIGN: Prospective clinical cohort study. ANIMALS: A total of 75 healthy client-owned dogs undergoing GA for elective tibial plateau levelling osteotomy. METHODS: After placing an intravenous catheter, dogs were premedicated with dexmedetomidine (5 µg kg-1) and methadone (0.3 mg kg-1) intravenously. After induction of GA with alfaxalone to effect, the bladder was expressed and USG measured. An arterial catheter was placed, and residual blood was used to measure packed cell volume (PCV) and total protein (TP). GA was maintained with isoflurane vaporised in oxygen and a femoral and sciatic nerve block were performed. Arterial blood pressure < 60 mmHg was defined as hypotension and recorded by the anaesthetist. Treatment for hypotension was performed in a stepwise manner following a flow chart. Frequency of hypotension, treatment and response to treatment were recorded. Logistic regression modelling was used to assess the association between USG, TP and PCV and incidence of perioperative hypotension; p < 0.05. RESULTS: Data from 14 dogs were excluded. Of the 61 dogs, 16 (26%) were hypotensive during GA, 15 dogs needed treatment of which 12 were responsive to a decrease in inhalant vaporiser setting. The logistic regression model was not statistically significant (p = 0.8). There was no significant association between USG (p = 0.6), TP (p = 0.4), PCV (p = 0.8) and arterial hypotension during GA. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs premedicated with dexmedetomidine and methadone and maintained under GA with isoflurane and a femoral and sciatic nerve block, there was no relationship between the specific gravity of urine collected after premedication and intraoperative arterial hypotension.

Effects of intravenous acepromazine and butorphanol on propofol dosage for induction of anesthesia in healthy Beagle dogs.

OBJECTIVE: To determine the effects of intravenous (IV) premedication with acepromazine, butorphanol or their combination, on the propofol anesthetic induction dosage in dogs. STUDY DESIGN: Prospective, blinded, Latin square design. ANIMALS: A total of three male and three female, healthy Beagle dogs, aged 3.79 ± 0.02 years, weighing 10.6 ± 1.1 kg, mean ± standard deviation. METHODS: Each dog was assigned to one of six IV treatments weekly: 0.9% saline (treatment SAL), low-dose acepromazine (0.02 mg kg-1; treatment LDA), high-dose acepromazine (0.04 mg kg-1; treatment HDA), low-dose butorphanol (0.2 mg kg-1; treatment LDB), high-dose butorphanol (0.4 mg kg-1; treatment HDB); and a combination of acepromazine (0.02 mg kg-1) with butorphanol (0.2 mg kg-1; treatment ABC). Physiologic variables and sedation scores were collected at baseline and 10 minutes after premedication. Then propofol was administered at 1 mg kg-1 IV over 15 seconds, followed by boluses (0.5 mg kg-1 over 5 seconds) every 15 seconds until intubation. Propofol dose, physiologic variables, recovery time, recovery score and adverse effects were monitored and recorded. Data were analyzed using mixed-effects anova (p < 0.05). RESULTS: Propofol dosage was lower in all treatments than in treatment SAL (4.4 ± 0.5 mg kg-1); the largest decrease was recorded in treatment ABC (1.7 ± 0.3 mg kg-1). Post induction mean arterial pressures (MAPs) were lower than baseline values of treatments LDA, HDA and ABC. Apnea and hypotension (MAP < 60 mmHg) developed in some dogs in all treatments with the greatest incidence of hypotension in treatment ABC (4/6 dogs). CONCLUSIONS AND CLINICAL RELEVANCE: Although the largest decrease in propofol dosage required for intubation was after IV premedication with acepromazine and butorphanol, hypotension and apnea still occurred.

Effects of dopamine, norepinephrine or phenylephrine on the prevention of hypotension in isoflurane-anesthetized cats administered vatinoxan or vatinoxan and dexmedetomidine.

OBJECTIVE: To determine the dose of phenylephrine, norepinephrine and dopamine necessary to maintain mean arterial pressure (MAP) within 70-80 mmHg during administration of isoflurane, isoflurane and vatinoxan and isoflurane, vatinoxan and dexmedetomidine at three plasma concentrations. STUDY DESIGN: Randomized crossover experimental study. ANIMALS: A group of five adult healthy neutered male cats. METHODS: Instrumentation occurred during anesthesia with isoflurane in oxygen. Isoflurane end-tidal concentration was set to 1.25 × minimum alveolar concentration (MAC). Phenylephrine, norepinephrine or dopamine was administered to maintain MAP 70-80 mmHg. A target-controlled infusion system was used to administer vatinoxan at a target plasma concentration of 1 µg mL-1 and three dexmedetomidine concentrations (5, 10 and 20 ng mL-1). Isoflurane concentration was altered to maintain an equivalent 1.25 MAC. Heart rate, arterial blood pressure, central venous pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, body temperature, arterial and mixed venous blood gas, cardiac output and drug concentrations were measured at baseline (isoflurane alone), during vatinoxan administration, and during administration of vatinoxan and dexmedetomidine at the three target concentrations. RESULTS: MAP < 70 mmHg was observed with vatinoxan alone and in the dopamine treatment with dexmedetomidine concentrations ≤ 10 ng mL-1. Norepinephrine and phenylephrine maintained MAP 70-80 mmHg during vatinoxan and dexmedetomidine ≤ 10 ng mL-1. As the target dexmedetomidine concentration increased, the dose of norepinephrine and phenylephrine needed to maintain MAP 70-80 mmHg decreased; no treatment was necessary to maintain MAP > 70 mmHg at the 20 ng mL-1 target dexmedetomidine concentration in most cats. CONCLUSIONS AND CLINICAL RELEVANCE: Norepinephrine and phenylephrine, but not dopamine, are effective to prevent hypotension in isoflurane-anesthetized cats administered dexmedetomidine and vatinoxan.

Early diagnosis of acute kidney injury subsequent to severe hypotension and fluid resuscitation in anaesthetized dogs.

OBJECTIVES: To document changes in urinary biomarker concentration and conventional diagnostic tests of acute kidney injury (AKI) following hypotension and fluid resuscitation in anaesthetized dogs. STUDY DESIGN: Experimental, repeated measures, prospective study. ANIMALS: A group of six male adult Greyhound dogs. METHODS: Following general anaesthesia, severe hypotension was induced by phlebotomy, maintaining mean arterial blood pressure (MAP) < 40 mmHg for 60 minutes, followed by resuscitation with intravenous gelatine solution to maintain MAP > 60 mmHg for 3 hours. Following euthanasia, renal tissue was examined by light microscopy (LM) and transmission electron microscopy (TEM). Urinary and serum concentrations of neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (CysC), and gamma-glutamyl transpeptidase (GGT), serum creatinine and urine output were measured at baseline and hourly until euthanasia. Data are presented as mean and 95% confidence interval and analysed using repeated measures analysis of variance with Dunnett's adjustment, p < 0.05. RESULTS: Structural damage to proximal renal tubular cells was evident on LM and TEM. Urinary biomarker concentrations were significantly elevated from baseline, peaking 2 hours after haemorrhage at 19.8 (15.1-25.9) ng mL-1 NGAL (p = 0.002), 2.54 (1.64-3.43) mg mL-1 CysC (p = 0.009) and 2043 (790-5458) U L-1 GGT (p < 0.001). Serum creatinine remained within a breed-specific reference interval in all dogs. Urinary protein-creatinine ratio (UPC) was significantly elevated in all dogs from 1 hour following haemorrhage. CONCLUSIONS AND CLINICAL RELEVANCE: Urinary NGAL, CysC and GGT concentrations, and UPC were consistently elevated within 1 hour of severe hypotension, suggesting that proximal renal tubules are damaged in the earliest stage of ischaemia-reperfusion AKI. Measurement of urinary biomarkers may allow early diagnosis of AKI in anaesthetized dogs. Urinary GGT concentration and UPC are particularly useful as they can be measured on standard biochemistry analysers.

Cardiovascular effects of dobutamine, norepinephrine and phenylephrine in isoflurane-anaesthetized dogs administered dexmedetomidine-vatinoxan.

OBJECTIVE: To determine whether dobutamine, norepinephrine or phenylephrine infusions alleviate hypotension in isoflurane-anaesthetized dogs administered dexmedetomidine with vatinoxan. STUDY DESIGN: Balanced, randomized crossover trial. ANIMALS: A total of eight healthy Beagle dogs. METHODS: Each dog was anaesthetized with isoflurane (end-tidal isoflurane 1.3%) and five treatments: dexmedetomidine hydrochloride (2.5 µg kg-1) bolus followed by 0.9% saline infusion (DEX-S); dexmedetomidine and vatinoxan hydrochloride (100 µg kg-1) bolus followed by an infusion of 0.9% saline (DEX-VAT-S), dobutamine (DEX-VAT-D), norepinephrine (DEX-VAT-N) or phenylephrine (DEX-VAT-P). The dexmedetomidine and vatinoxan boluses were administered at baseline (T0) and the treatment infusion was started after 15 minutes (T15) if mean arterial pressure (MAP) was < 90 mmHg. The treatment infusion rate was adjusted every 5 minutes as required. Systemic haemodynamics were recorded at T0 and 10 (T10) and 45 (T45) minutes. A repeated measures analysis of covariance model was used. RESULTS: Most dogs had a MAP < 70 mmHg at T0 before treatment. Treatments DEX-S and DEX-VAT all significantly increased MAP at T10, but systemic vascular resistance index (SVRI) was significantly higher and cardiac index (CI) lower after DEX-S than after DEX-VAT. CI did not significantly differ between DEX-S and DEX-VAT-S at T45, while SVRI remained higher with DEX-S. Normotension was achieved by all vasoactive infusions in every dog, whereas MAP was below baseline with DEX-VAT-S, and higher than baseline with DEX-S at T45. Median infusion rates were 3.75, 0.25 and 0.5 µg kg-1 minute-1 for dobutamine, norepinephrine and phenylephrine, respectively. Dobutamine and norepinephrine increased CI (mean ± standard deviation, 3.35 ± 0.70 and 3.97 ± 1.24 L minute-1 m-2, respectively) and decreased SVRI, whereas phenylephrine had the opposite effect (CI 2.13 ± 0.45 L minute-1 m-2). CONCLUSIONS AND CLINICAL RELEVANCE: Hypotension in isoflurane-anaesthetized dogs administered dexmedetomidine and vatinoxan can be treated with either dobutamine or norepinephrine.

THE USE OF EPHEDRINE TO TREAT ANESTHESIA-ASSOCIATED HYPOTENSION IN PINNIPEDS.

Hypotension is a common adverse effect of general anesthesia that has historically been difficult to measure in pinniped species due to technical challenges. A retrospective case review found seven pinniped cases that demonstrated anesthesia-associated hypotension diagnosed by direct blood pressure measurements during general anesthesia at The Marine Mammal Center (Sausalito, CA) between 2017 and 2019. Cases included five California sea lions (CSL: Zalophus californianus), one Hawaiian monk seal (HMS: Neomonachus schauinslandi), and one northern elephant seal (NES: Mirounga angustirostris). Patients were induced using injectable opioids, benzodiazepines, and anesthetics including propofol and alfaxalone. Excluding the HMS, all patients required supplemental isoflurane with a mask to achieve an anesthetic plane allowing for intubation. Each patient was maintained with inhalant isoflurane in oxygen for the duration of the anesthetic event. Each patient was concurrently administered continuous IV fluids and four patients received fluid boluses prior to administration of ephedrine. All hypotensive anesthetized patients were treated with IV ephedrine (0.05-0.2 mg/kg). The average initial systolic (SAP) and mean (MAP) arterial blood pressures for the CSL prior to ephedrine administration were 71 ± 14 mmHg and 48 ± 12 mmHg respectively. The average SAP and MAP for the CSL increased to 119 ± 32 mmHg and 90 ± 34 mmHg respectively within 5 m of ephedrine administration. The NES initial blood pressure measurement was 59/43 (50) (SAP/diastolic [MAP]) mmHg and increased to 80/51 (62) mmHg within 5 m. The initial HMS blood pressure was 79/68 (73) mmHg and increased to 99/78 (85) mmHg within 5 m following ephedrine administration. All patients recovered from anesthesia. These results support the efficacy of IV ephedrine for the treatment of anesthesia-associated hypotension in pinnipeds.

Review of non-invasive blood pressure measurement in animals: Part 2 - Evaluation of the performance of non-invasive devices.

Arterial blood pressure is a common parameter evaluated in conscious and anesthetized veterinary patients for a variety of reasons. Non-invasive blood pressure measurement techniques, such as Doppler ultrasound and oscillometry, are attractive in certain veterinary patients due to their availability and ease of use. The greatest limitation to non-invasive blood pressure monitoring can be its inaccuracy, particularly in hypotensive or hypertensive patients and in certain species. Part 1 of this 2-part review summarized the current techniques available to non-invasively measure arterial blood pressure in veterinary species and discussed validation of non-invasive devices. Part 2 summarizes the veterinary literature that evaluates the use of non-invasive blood pressure measurement techniques in conscious and anesthetized species and develops general conclusions for proper use and interpretation of non-invasive blood pressure devices.

Mesure de la pression sanguine de manière non-invasive chez les animaux. Partie 2 ­ Évaluation de la performance des équipements non-invasifs. La pression sanguine artérielle est un paramètre fréquemment évalué chez les patients vétérinaires conscients et anesthésiés pour une variété de raisons. Les techniques noninvasives de mesure de la pression sanguine, telles que les ultrasons Doppler et l'oscillométrie, sont intéressantes chez certains patients vétérinaires étant donné leur disponibilité et leur facilité d'utilisation. La principale limitation du suivi de la pression sanguine par des méthodes non-invasives peut être son imprécision, particulièrement chez des patients hypotensifs ou hypertensifs, et chez certaines espèces. La première partie de cette revue en deux parties résumait les techniques présentement disponibles pour mesurer de manière non-invasive la pression sanguine artérielle chez des espèces animales et discutait de la validation des équipements non-invasifs. La deuxième partie résume la littérature vétérinaire qui évalue l'utilisation de techniques non-invasives de mesure de la pression sanguine chez des espèces conscientes et anesthésiées et développe des conclusions générales pour l'utilisation et l'interprétation appropriées des équipements non-invasifs de mesure de la pression sanguine.(Traduit par Dr Serge Messier).

Non-invasive blood pressure measurement in animals: Part 1 - Techniques for measurement and validation of non-invasive devices.

Arterial blood pressure is a common parameter evaluated in conscious and anesthetized veterinary species. Non-invasive blood pressure measurement techniques, such as Doppler ultrasonic flow detector and oscillometry, are attractive in certain animals due to their availability and ease of use. The greatest limitation to non-invasive blood pressure monitoring can be its inaccuracy, particularly in hypotensive or hypertensive patients and in certain species. Part 1 of this 2-part review summarizes the current techniques available to non-invasively measure arterial blood pressure in animals and discusses validation of non-invasive devices. Part 2 summarizes the veterinary literature that evaluates the use of non-invasive blood pressure measurement techniques in conscious and anesthetized species and develops general conclusions for proper use and interpretation of data from non-invasive blood pressure devices.

Mesures de la pression sanguine chez les animaux de manière non-invasive: Partie 1 ­ Techniques pour mesurer et validation d'appareils non-invasifs. La pression sanguine artérielle est un paramètre fréquemment évalué chez les espèces animales conscientes et anesthésiées. Des techniques non-invasives de mesure de la pression sanguine, telles que le détecteur ultra-sonique de flot Doppler et l'oscillométrie, sont attirantes chez certains animaux étant donné leur disponibilité et facilité d'utilisation. La plus grande limitation au suivi non-invasif de la pression sanguine peut être son imprécision, particulièrement chez les patients hypotensifs ou hypertensifs et chez certaines espèces. La partie 1 de cette revue en deux parties résume les techniques présentement disponibles pour mesurer de manière non-invasive la pression sanguine artérielle chez des animaux et discute la validation d'équipements non-invasifs. La partie 2 résume la littérature vétérinaire qui évalue l'utilisation de techniques de mesure non-invasives de la pression sanguine chez des espèces conscientes et anesthésiées et développe des conclusions générales pour l'utilisation appropriée et l'interprétation des données obtenues d'équipements noninvasifs de mesure de la pression sanguine.(Traduit par Dr Serge Messier).

Cardiopulmonary effects of dexmedetomidine, with and without vatinoxan, in isoflurane-anesthetized cats.

OBJECTIVE: To characterize the cardiopulmonary effects of dexmedetomidine, with or without vatinoxan, in isoflurane-anesthetized cats. STUDY DESIGN: Randomized, crossover experimental study. ANIMALS: A group of six adult healthy male neutered cats. METHODS: Cats were instrumented during anesthesia with isoflurane in oxygen. Isoflurane end-tidal concentration was set to 1.25 minimum alveolar concentration (MAC). Dexmedetomidine was administered using a target-controlled infusion system to achieve and maintain 10 target plasma concentrations ranging from 0 to 40 ng mL-1. Furthermore, vatinoxan or an equivalent volume of saline was administered using a target-controlled infusion system to achieve and maintain a target plasma concentration of 4 µg mL-1. Isoflurane concentration was adjusted after each change in dexmedetomidine concentration to maintain a concentration equivalent to 1.25 MAC. Heart rate (HR), arterial blood pressure, central venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary artery occlusion pressure (PAOP), body temperature, cardiac output, arterial and mixed-venous blood gas and pH and drug concentrations were measured. Additional variables were calculated from the measurements. RESULTS: Dexmedetomidine alone resulted in decreased HR, cardiac index, stroke index and oxygen delivery, and increased systolic, mean (MAP) and diastolic arterial pressure, CVP, PAP, PAOP, systemic vascular resistance index, rate-pressure product, left ventricular stroke work index and oxygen extraction ratio. Vatinoxan resulted in severe hypotension at target plasma dexmedetomidine concentrations <10 ng mL-1. Vatinoxan attenuated the cardiovascular effects of dexmedetomidine at the 10 and 20 ng mL-1 targets, but MAP could be maintained above 60 mmHg only when isoflurane concentration was <1.25 MAC. Less improvement in cardiovascular function was seen with vatinoxan at the 40 ng mL-1 target plasma dexmedetomidine concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Vatinoxan, at the plasma concentration maintained in this study, attenuated the cardiovascular effects of dexmedetomidine in isoflurane-anesthetized cats. However, its administration resulted in hypotension, which may limit its clinical usefulness.

Vasopressor use in 41 critically ill cats (2007-2016).

This study describes the use of vasopressors in critically ill cats. Records of 41 cats hospitalized in the ICU were evaluated. Signalment, blood pressure, underlying conditions, evidence of sepsis, type of treatment (surgical versus non-surgical), vasopressor type and duration, adverse events attributed to vasopressors, and survival were recorded. Twenty-one cats (51%) had an underlying disease considered amenable to surgical treatment while 20 (49%) cats did not. Evidence of sepsis was present in 24 (59%) cats. Thirty-four cats developed a Doppler blood pressure (DBP) > 80 mmHg during therapy, and 29 cats became normotensive (DBP > 90 mmHg). Seven cats did not increase their DBP to > 80 mmHg. All cats received dopamine and/or norepinephrine and 6 cats also received other vasopressors. Sixteen cats survived (39%). Surgical intervention was associated with a higher survival (P = 0.004). Critically ill hypotensive cats may benefit from administration of vasopressors.

Utilisation de vasopressine chez 41 chats en état critique (2007­2016). Cette étude décrit l'utilisation de vasopresseurs chez les chats en condition critique. Les dossiers médicaux de 41 chats hospitalisés ont été évalués. Le signalement, pression sanguine, conditions sous-jacentes, évidence de sepsis, type de traitement (chirurgical contre médical), type de vasopresseurs et durée, effets adverses reliés à l'utilisation des vasopresseurs et survie ont été comptabilisés. Vingt et un chats (51 %) avaient une condition sous-jacente susceptible au traitement chirurgical contrairement aux 20 autres chats (49 %). L'évidence de sepsis était présente dans 24 (59 %) chats. Trente-quatre chats ont développé une pression sanguine au Doppler (DBP) > 80 mmHg durant le traitement et 29 chats sont devenus normotensifs (DBP > 90 mmHg). Sept chats n'ont pas eu d'augmentation de leur DBP > 80 mmHg. Tous les chats ont reçu de la dopamine et/ou de la norépinéphrine et 6 chats ont reçus d'autres vasopresseurs. Seize chats ont survécu (39 %). Une intervention chirurgicale est associée à un plus grand taux de survie (P = 0,004). Les chats hypotensifs en condition critique peuvent bénéficier de l'utilisation de vasopresseurs.(Traduit par les auteurs).

Evaluation of an indirect oscillometric blood pressure monitor in anaesthetised dogs at three different anatomical locations.

AIMS: To evaluate the agreement between invasive and non-invasive measurements of blood pressure (BP) using an oscillometer (PetTrust) at three different anatomical locations in anaesthetised dogs under different haemodynamic conditions. METHODS: Eight adult Greyhounds weighing 23.5-36.5 kg were anaesthetised with isoflurane and positioned in dorsal recumbency. Systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) were measured invasively via a dorsal pedal artery and non-invasively using the oscillometer with cuffs placed above the carpus, above the tarsus and around the tail base. Phenylephrine was administered to induce vasoconstriction, dobutamine was used to increase cardiac output and increased end-tidal concentrations of isoflurane were used to induce vasodilation. Correlation between measurements was analysed by linear regression and agreement was analysed using Bland-Altman plots. RESULTS: Seventy two representative measurements were obtained. Mean differences (bias) between invasive and non-invasive measurements were <5 mmHg except for DAP measured on the tail, and SD (precision) were <15 mm Hg except for SAP measured at the pelvic limb. Correlation coefficients were >0.9 except for SAP on the pelvic limb and DAP on the tail. More than 50 and 80% of values measured using oscillometry lay within 10 and 20 mmHg, respectively, of values measured invasively except for SAP on the tail. SAP tended to be overestimated when measured non-invasively at low BP, and be underestimated at high BP. DAP was underestimated during low BP and overestimated during high BP. Hypotension (MAP <60 mmHg) was detected by the oscillometer with a sensitivity ≥83% and specificity ≥98% at all locations. CONCLUSIONS: This oscillometric device met the 2007 American College of Veterinary Internal Medicine guidelines for measurement of BP on the thoracic limb. There was good agreement between the oscillometer and invasive measurement of MAP at all locations. CLINICAL RELEVANCE: MAP is the driving pressure for tissue perfusion, thus MAP measurement is clinically essential. This oscillometric device yields reliable MAP measurements at three anatomical locations over a wide range of BP and can identify hypotension with high sensitivity and specificity.

What is the definition of intraoperative hypotension in dogs? Results from a survey of diplomates of the ACVAA and ECVAA.

OBJECTIVE: Determine arterial blood pressure range that diplomates of the American College of Veterinary Anesthesia and Analgesia (ACVAA) and European College of Veterinary Anaesthesia and Analgesia (ECVAA) use to define intraoperative hypotension in dogs and identify the threshold values used for intervention. STUDY DESIGN: Survey of veterinary anesthesia specialists. POPULATION: Diplomates of the ACVAA and ECVAA. METHODS: ACVAA and ECVAA diplomates (n = 313) were invited to participate in an Internet-based survey regarding anesthetized healthy dogs undergoing two types of procedures (diagnostic or surgical). RESULTS: There were 151 respondents to the survey; 70.2% were ACVAA diplomates and 29.8% were ECVAA diplomates. The majority of the respondents (70.9%) worked in academia while the others were in private practice (19.2%), or research, diagnostic or pharmaceutical fields (9.9%). Hypotension was defined (mean ± SD) by the respondents as systolic arterial blood pressure (SAP) <87 ± 8 mmHg for surgical cases and <87 ± 6 mmHg for diagnostic cases, or mean arterial pressure (MAP) <62 ± 4 mmHg for both types of cases. Arterial pressures reported to prompt treatment were SAP 85 ± 13 mmHg or MAP 61 ± 4 mmHg in surgical cases, and SAP 84 ± 11 mmHg or MAP 63 ± 8 mmHg in diagnostic cases. CONCLUSIONS AND CLINICAL RELEVANCE: There was agreement between ACVAA and ECVAA diplomates on the definition of intraoperative hypotension in dogs during anesthesia. The blood pressures used to define hypotension were similar to the pressures that would prompt diplomates to start treatment. Readers could infer that diplomates define hypotension as a clinical condition that requires treatment at the time of diagnosis.

Association between decreased blood pressure and azotaemia in canine babesiosis.

Acute tubular necrosis (ATN) was described in canine babesiosis. Hypotension is considered as one of the factors which influence the development of hypoxic renal damage. In this study hypotension defined as mean arterial pressure (MAP) < 80 mmHg was detected in 7 out of 48 dogs (14.6%) infected with Babesia canis. Lower systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and MAP were detected in azotaemic dogs infected with B. canis. Statistically significant negative correlations between blood pressures (SAP, DAP and MAP) and serum creatinine and urea concentrations showed the influence of decreased blood pressure on the development of azotaemia and is probably also associated with ATN in canine babesiosis.

What is the best treatment for hypotension in healthy dogs during anaesthesia maintained with isoflurane?

Hypotension is a common and potentially life-threatening complication of general anaesthesia in dogs. Due to the combination of cardiovascular side effects of many anaesthetic, sedative and analgesic drugs used peri-operatively hypotension is frequently reported even in healthy dogs undergoing elective procedures. Several treatment options for hypotension have been advocated. Potential treatments include rapid administration of either crystalloid or colloid fluids; pharmacological treatments to increase cardiac output and/or systemic vascular resistance; or reduction in the delivery of the volatile anaesthetic agents. This critical appraisal considers the current evidence for which treatment is the best option for treating hypotension in healthy euvolemic dogs undergoing general anaesthesia maintained with isoflurane. Fourteen relevant studies were appraised, including 12 laboratory studies and two small clinical trials. One study demonstrated that reduction in the delivery of isoflurane may correct hypotension, but this treatment may not always be feasible. In general, rapid administration of fluids did not increase blood pressure and failed to correct hypotension. Synthetic colloids demonstrated some efficacy, but results were inconsistent between studies and large volumes may be required. Infusion of dopamine appears to be the most reliable pharmacological option consistently increasing blood pressure, cardiac output and correcting hypotension.