Systolic Blood Pressure in Anesthetized Dogs - Agreement between Measurements by Two Noninvasive Monitors

Background: The oscillometric monitor is a noninvasive method used for measuring blood pressure in dogs and cats. Despite widely used, there is a large variability in the accuracy of oscillometric monitors, which may also be influenced by the location of the blood pressure cuff. The Doppler ultrasound is another non-invasive method that was shown to measure blood pressure with good accuracy and precision in small animals. The present study aimed to determine the agreement between systolic arterial pressure (SAP) measured by the Prolife P12 oscillometric monitor with two cuff locations and the Doppler ultrasound in anesthetized dogs.Materials, Methods & Results: Dogs scheduled for routine anesthetic procedures were included in the study, which was carried out in two phases. In Phase 1, SAP values measured by the Doppler were compared with those measured by the Prolife P12 monitor with the cuff placed at the thoracic limb for both methods. In Phase 2, SAP values measured by the Doppler were compared with those measured by the Prolife P12 monitor, with the cuff placed at the thoracic limb for the Doppler and at the base of the tail for the P12. The cuff width corresponded to approximately 40% of limb or tail circumference. On all occasions, three consecutive measurements of SAP were recorded, followed by a single measurement of SAP by the P12, and then other three measurements were performed with the Doppler. The arithmetic mean of the six SAP measurements with the Doppler was compared with the SAP value measured by the P12 monitor (paired measurements). Agreement between SAP values measured by the Doppler and the P12 monitor was analyzed by the Bland Altman method for calculation of the bias (Doppler – P12) and standard deviation (SD) of the bias. The percentages of differences between the methods with an error ≤ 10 mmHg and ≤ 20 mmHg and Pearson’s correlation coefficients were also calculated. Results were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of noninvasive blood pressure methods. A total of 33 dogs were included in Phase 1 and 15 were included in Phase 2. During Phases 1 and 2, 179 and 87 paired measurements were recorded, respectively. Most of the measurements were recorded during normotension (SAP = 90-130 mmHg): 113/179 in Phase 1 and 52/87 in Phase 2. The bias (± SD) for Phases 1 and 2 were -2.7 ± 14.1 mmHg and 7.2 ± 25.8 mmHg. The percentages of differences ≤ 10 mmHg and ≤ 20 mmHg were: Phase 1, 61% and 83%; Phase 2, 41% and 70%. Correlation coefficients were 0.81 and 0.67 for Phases 1 and 2, respectively. According to the ACVIM criteria, maximum values accepted for bias are 10 ± 15 mmHg, the percentages of differences ≤ 10 mmHg and ≤ 20 mmHg should be ³ 50% and ³ 80%, respectively, and the correlation coefficient should be ³ 0.9. Discussion: When the blood pressure cuff was placed at the thoracic limb, SAP values measured by the P12 monitor met most of the ACVIM criteria, demonstrating good agreement with SAP values measured by the Doppler. The only requirement not met was the correlation coefficient which was 0.81 whereas the recommended is ³ 0.9. Conversely, when the cuff was placed at the base of the tail, SAP values measured by the P12 monitor did not meet most of the ACVIM criteria indicating that, in anesthetized dogs, SAP measurements with the P12 monitor should be performed with the cuff placed at the thoracic limb. One limitation of this study was that most measurements fell in the normotensive range and the results should not be extrapolated for hypotensive and hypertensive conditions. In conclusion, the Prolife P12 oscillometric monitor demonstrated good agreement with SAP values measured by the Doppler and provides acceptable values in normotensive anesthetized dogs.Keywords: arterial blood pressure, nonivasive blood pressure, anesthetic monitoring.Título: Pressão arterial sistólica em cães anestesiados - concordância entre mensurações por dois métodos não invasivosDescritores: pressão arterial, pressão arterial não invasiva, monitoração anestésica

Treatment of an atypical case of bilateral nephrolithiasis in a canine

Background: Less than 5% of canine uroliths are found in the kidney and ureter. The decision to remove a nephrolith is controversial and should be considered in cases of refractory infection, hematuria, presence of obstructive uropathy and compression of the renal parenchyma. The aim of this report is to describe an unusual presentation of bilateral nephrolithiasis in a dog, occupying almost the entire renal parenchyma, its clinical and imaging findings, in addition to surgical treatment and its evolution. Case: A 10-year-old male Basset Hound was evaluated at the Veterinary Medical Teaching Hospital (HCV) of the Federal University of Rio Grande do Sul (UFRGS), presenting prostration, anorexia, vomiting, diarrhea and severe hematuria for three days. On physical examination the patient was dehydrated, with pale mucous membranes, uremic breath and abdominal pain. Blood tests showed mild anemia and azotemia. In both kidneys, abdominal ultrasonography exhibited a large hyperechoic structure with deep acoustic shadowing. These same structures were observed in abdominal radiographic examination as radiopaque structures, confirming the diagnosis of bilateral nephrolithiasis. Urine culture was positive for coagulase-negative Staphylococcus sp. The patient was stabilized with fluid therapy, antiemetic, analgesics, antibiotics and whole blood transfusion. Unilateral nephrotomy of the right kidney was performed to remove the urolith. After three months, nephrotomy of the left kidney was performed to remove the other urolith. The patient was clinically stable and with no macroscopic hematuria 12 h after surgery. Two days after discharge, the patient returned prostrated in lateral recumbency, however with no alteration of parameters in physical examination. Blood tests showed anemia, thrombocytopenia, hypoalbuminemia, azotemia and hyperphosphatemia. The dog presented a convulsive episode and died shortly, eight hours later. In the necropsy examination, extensive loss of renal parenchyma was seen in both kidneys and the presence of thrombosis and areas of infarction in several organs such as spleen, liver, lungs and central nervous system. Discussion: Complications of nephrotomy include perirenal hemorrhage, hydronephrosis due to obstruction of blood clots or urine leakage to the abdominal cavity. From the necropsy findings, the surgical site did not present these complications, justifying that the surgical procedure was not directly related to death. Correction of dehydration, blood transfusion, and antibiotic therapy based on urine culture and susceptibility testing was important for initial stabilization, before surgery. However, the presence of advanced chronic kidney disease may have contributed to deterioration of the patient’s clinical condition and death. The presence of thrombus and hemorrhagic areas, observed during necropsy, associated with acute onset of clinical signs and the presence of severe hypoalbuminemia, may suggest that the patient died due to a thromboembolic event, as a consequence of nephrotic syndrome. Studies show that nephrotomy can be performed with few adverse effects on renal function if the surgical technique and anesthetic management are adequate. In this case, nephrotomy was the best option for the treatment of the patient, since it enabled a rapid intervention, controlled the hematuria and allowed the removal of both uroliths without complications related to surgery

Systolic blood pressure in anesthetized dogs : agreement between measurements by two noninvasive monitors

Background: The oscillometric monitor is a noninvasive method used for measuring blood pressure in dogs and cats. Despite widely used, there is a large variability in the accuracy of oscillometric monitors, which may also be influenced by the location of the blood pressure cuff. The Doppler ultrasound is another non-invasive method that was shown to measure blood pressure with good accuracy and precision in small animals. The present study aimed to determine the agreement between systolic arterial pressure (SAP) measured by the Prolife P12 oscillometric monitor with 2 cuff locations and the Doppler ultrasound in anesthetized dogs. Materials, Methods & Results: Dogs scheduled for routine anesthetic procedures were included in the study, which was carried out in 2 phases. In Phase 1, SAP values measured by the Doppler were compared with those measured by the Prolife P12 monitor with the cuff placed at the thoracic limb for both methods. In Phase 2, SAP values measured by the Doppler were compared with those measured by the Prolife P12 monitor, with the cuff placed at the thoracic limb for the Doppler and at the base of the tail for the P12. The cuff width corresponded to approximately 40% of limb or tail circumference. On all occasions, 3 consecutive measurements of SAP were recorded, followed by a single measurement of SAP by the P12, and then other 3 measurements were performed with the Doppler. The arithmetic mean of the 6 SAP measurements with the Doppler was compared with the SAP value measured by the P12 monitor (paired measurements). Agreement between SAP values measured by the Doppler and the P12 monitor was analyzed by the Bland Altman method for calculation of the bias (Doppler - P12) and standard deviation (SD) of the bias. The percentages of differences between the methods with an error ≤ 10 mmHg and ≤ 20 mmHg and Pearson’s correlation coefficients were also calculated. Results were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of noninvasive blood pressure methods. A total of 33 dogs were included in Phase 1 and 15 were included in Phase 2. During Phases 1 and 2, 179 and 87 paired measurements were recorded, respectively. Most of the measurements were recorded during normotension (SAP = 90-130 mmHg): 113/179 in Phase 1 and 52/87 in Phase 2. The bias (± SD) for Phases 1 and 2 were -2.7 ± 14.1 mmHg and 7.2 ± 25.8 mmHg. The percentages of differences ≤ 10 mmHg and ≤ 20 mmHg were: Phase 1, 61% and 83%; Phase 2, 41% and 70%. Correlation coefficients were 0.81 and 0.67 for Phases 1 and 2, respectively. According to the ACVIM criteria, maximum values accepted for bias are 10 ± 15 mmHg, the percentages of differences ≤ 10 mmHg and ≤ 20 mmHg should be ≥ 50% and ≥ 80%, respectively, and the correlation coefficient should be ≥ 0.9. Discussion: When the blood pressure cuff was placed at the thoracic limb, SAP values measured by the P12 monitor met most of the ACVIM criteria, demonstrating good agreement with SAP values measured by the Doppler. The only requirement not met was the correlation coefficient which was 0.81 whereas the recommended is ≥ 0.9. Conversely, when the cuff was placed at the base of the tail, SAP values measured by the P12 monitor did not meet most of the ACVIM criteria indicating that, in anesthetized dogs, SAP measurements with the P12 monitor should be performed with the cuff placed at the thoracic limb. One limitation of this study was that most measurements fell in the normotensive range and the results should not be extrapolated for hypotensive and hypertensive conditions. In conclusion, the Prolife P12 oscillometric monitor demonstrated good agreement with SAP values measured by the Doppler and provides acceptable values in normotensive anesthetized dogs

Sedative and cardiorespiratory effects of methadone, alone or in combination with acepromazine or xylazine, in cats

Seis felinos com peso médio de 3,3±0,3 kg foram aleatoriamente submetidos a 6 tratamentos, com intervalo mínimo de 1 semana. Os animais receberam a administração intramuscular de solução fisiológica (controle), metadona (0,3 mg/kg), acepromazina (0,1 mg/kg), xilazina (1,0 mg/kg), acepromazina (0,05 mg/kg) + metadona (0,3 mg/kg) ou xilazina (0,5 mg/kg) + metadona (0,3 mg/kg). As freqüências cardíaca (FC) e respiratória (FR), a pressão arterial sistólica (PAS), a temperatura retal, o grau de sedação e o reflexo interdigital foram avaliados antes (basal) e após a administração dos tratamentos em intervalos específicos por 90 minutos. Nos animais tratados com xilazina ou xilazina/metadona, houve diminuição em FR, FC e na temperatura retal. Nos mesmos tratamentos, 1/6 e 2/6 animais não apresentaram reflexo interdigital em pelo menos um dos momentos avaliados. Nos animais que receberam a administração de 0,1 mg/kg de acepromazina, houve diminuição em PAS. Os escores de sedação foram mais elevados nos animais que receberam a administração de xilazina ou xilazina associada à metadona. A administração da metadona isolada ou associada à acepromazina resultou em sedação considerada insatisfatória e sinais de excitação em alguns animais. O uso da metadona isolado ou em associação à acepromazina foi considerado ineficaz quando se objetiva sedação moderada à intensa. A associação da metadona à xilazina produz sedação moderada à intensa, sendo esse efeito semelhante àquele observado após a administração da xilazina isoladamente em dose mais elevada.Six cats weighting 3.3±0.3 kg were randomly allocated to 6 treatments, with at least one-week intervals. The cats received intramuscular administration of physiological saline (control), methadone (0.3 mg/kg), acepromazine (0,1 mg/kg), xylazine (1.0 mg/kg), acepromazine (0.05 mg/kg) plus methadone (0.3 mg/kg) or xylazine (0.5 mg/kg) plus methadone (0.3 mg/kg). Heart rate (HR), respiratory rate (RR), indirect systolic arterial pressure (SAP), rectal temperature, sedation score and pedal withdrawal reflex were evaluated before (baseline) and at selected intervals after treatment administration for 90 minutes. Respiratory rate, HR and rectal temperature decreased in cats given xylazine or xylazine plus methadone. In 1 out of 6 cats given xylazine and 2 out of 6 cats given xylazine/methadone, pedal withdrawal reflex was absent. In cats given 0.1 mg/kg of acepromazine, SAP decreased compared to baseline. Sedation scores were greater in cats given xylazine or xylazine plus methadone. Methadone alone or in combination with acepromazine did not produce a satisfactory degree of sedation and resulted in signs of excitement in some of the cats. Methadone alone or combination with acepromazine was not considered an effective protocol when moderate to deep sedation is required in cats. Methadone in combination with xylazine produces moderate to deep sedation, being this effect comparable to that achieved with a higher dose of xylazine alone

Evaluation of the accuracy and precision of the GE Dash 4000 oscillometric monitor for blood pressure measurement in anesthetized female dogs

Background: Indirect measurement of arterial blood pressure, such as the oscillometric method, is the most commonly used in clinical practice of dogs and cats. This method measures blood pressure values that are estimates of direct (invasive) arterial blood pressure values. Oscillometric devices are easy to use even for non-experienced personnel. However, there is considerable variation in accuracy and precision of blood pressure values measured by different oscillometric monitors. The present study aimed to determine the accuracy and precision of the GE Dash 4000 oscillometric monitor for arterial blood pressure measurement in anesthetized female dogs. Materials, Methods & Results: Sixteen healthy adult female dogs received 0.3 mg/kg morphine as premedication and were anesthetized with propofol and isoflurane. A 22-gauge catheter was introduced into the dorsal pedal artery and connected to a rigid tubular system and a pressure transducer filled with heparinized solution to allow direct (invasive) measurement of systolic (SAP), mean (MAP) and diastolic arterial pressure (DAP). A blood pressure cuff was positioned proximal to the carpus and connected to the oscillometric device (GE-DASH 4000 monitor) in order to obtain indirect measurements of SAP, MAP and DAP. Cuff width was 40% of limb circumference. During anesthesia, invasive arterial blood pressure values were measured and recorded simultaneously with the oscillometric method. The Bland Altman method was used to evaluate agreement between the methods by calculating the bias (invasive - oscillometric) and limits of agreement. Percentages of differences between the methods with an error ≤ 10 mmHg and ≤ 20 mmHg were calculated. Results were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of noninvasive blood pressure methods Weight and age of dogs were 7.6 ± 2.2 kg and 20 ± 17 months, respectively. A total of 195 pairs of measurements were obtained from 16 animals. Of these pairs, 146 were classified as normotension (SAP: 90 to 140 mmHg), 28 as hypertension (SAP > 140 mmHg) and 21 as hypotension (SAP < 90 mmHg). Bias values ± SD (95% limits of agreement) were: SAP, 5.0 ± 16.5 mmHg (-27.3 to 37.4 mmHg); MAP, -3.4 ± 14.3 mmHg (-31.4 to 24.6 mmHg); and DAP, 4.2 ± 11.8 mmHg (-18.9 to 27.4 mmHg). According to the ACVIM criteria, maximum values accepted for bias (± SD) are 10 ± 15 mmHg. Percentages of differences ≤ 10 mmHg and ≤ 20 mmHg were: SAP, 41% and 80%; MAP, 54% and 84%; and DAP, 64% and 91%. ACVIM recommendations are ≥ 50% for errors within 10 mmHg and ≥ 80% for errors within 20 mmHg. Discussion: MAP and DAP values obtained by the GE-DASH 4000 monitor matched the ACVIM criteria for validation of noninvasive methods. Conversely, SAP values did not meet all the criteria, and were not considered reliable. Limitations of the study include: a) most dogs were of low weight; b) the ACVIM criteria refer to SAP measurements, but in the present study, the same criteria were applied to MAP and DAP measurements; c) the majority of observations were obtained during normotension. We conclude that MAP and DAP measurements obtained by the GE Dash 4000 monitor met the ACVIM criteria for validation of noninvasive blood pressure monitors. Therefore, this monitor was considered to have adequate accuracy and precision for MAP and DAP measurements in anesthetized normotensive dogs. Under the conditions of this study, SAP measurements obtained by this monitor were not reliable

Evaluation of the Accuracy and Precision of the GE Dash 4000 Oscillometric Monitor for Blood Pressure Measurement in Anesthetized Female Dogs

Background: Indirect measurement of arterial blood pressure, such as the oscillometric method, is the most commonly used in clinical practice of dogs and cats. This method measures blood pressure values that are estimates of direct (invasive) arterial blood pressure values. Oscillometric devices are easy to use even for non-experienced personnel. However, there is considerable variation in accuracy and precision of blood pressure values measured by different oscillometric monitors. The present study aimed to determine the accuracy and precision of the GE Dash 4000 oscillometric monitor for arterial blood pressure measurement in anesthetized female dogs.Materials, Methods & Results: Sixteen healthy adult female dogs received 0.3 mg/kg morphine as premedication and were anesthetized with propofol and isoflurane. A 22-gauge catheter was introduced into the dorsal pedal artery and connected to a rigid tubular system and a pressure transducer filled with heparinized solution to allow direct (invasive) measurement of systolic (SAP), mean (MAP) and diastolic arterial pressure (DAP). A blood pressure cuff was positioned proximal to the carpus and connected to the oscillometric device (GE-DASH 4000 monitor) in order to obtain indirect measurements of SAP, MAP and DAP. Cuff width was 40% of limb circumference. During anesthesia, invasive arterial blood pressure values were measured and recorded simultaneously with the oscillometric method. The Bland Altman method was used to evaluate agreement between the methods by calculating the bias (invasive - oscillometric) and limits of agreement. Percentages of differences between the methods with an error ≤ 10 mmHg and ≤ 20 mmHg were calculated. Results were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of noninvasive blood pressure methods. Weight and age of dogs were 7.6 ± 2.2 kg and 20 ± 17 months, respectively. A total of 195 pairs of measurements were obtained from 16 animals. Of these pairs, 146 were classified as normotension (SAP: 90 to 140 mmHg), 28 as hypertension (SAP > 140 mmHg) and 21 as hypotension (SAP < 90 mmHg). Bias values ± SD (95% limits of agreement) were: SAP, 5.0 ± 16.5 mmHg (-27.3 to 37.4 mmHg); MAP, -3.4 ± 14.3 mmHg (-31.4 to 24.6 mmHg); and DAP, 4.2 ± 11.8 mmHg (-18.9 to 27.4 mmHg). According to the ACVIM criteria, maximum values accepted for bias (± SD) are 10 ± 15 mmHg. Percentages of differences ≤ 10 mmHg and ≤ 20 mmHg were: SAP, 41% and 80%; MAP, 54% and 84%; and DAP, 64% and 91%. ACVIM recommendations are ≥ 50% for errors within 10 mmHg and ≥ 80% for errors within 20 mmHg.Discussion: MAP and DAP values obtained by the GE-DASH 4000 monitor matched the ACVIM criteria for validation of noninvasive methods. Conversely, SAP values did not meet all the criteria, and were not considered reliable. Limitations of the study include: a) most dogs were of low weight; b) the ACVIM criteria refer to SAP measurements, but in the present study, the same criteria were applied to MAP and DAP measurements; c) the majority of observations were obtained during normotension. We conclude that MAP and DAP measurements obtained by the GE Dash 4000 monitor met the ACVIM criteria for validation of noninvasive blood pressure monitors. Therefore, this monitor was considered to have adequate accuracy and precision for MAP and DAP measurements in anesthetized normotensive dogs. Under the conditions of this study, SAP measurements obtained by this monitor were not reliable

Abordagens subzigomática e infraorbitária para o bloqueio do nervo maxilar em cadáver de gatos

This study compared the accuracy of dye placement on the maxillary nerve by using the percutaneous subzigomatic (SBZ) and infraorbitary (IO) approaches in cats’ cadavers. A second aim was to compare the accuracy of dye placement on the maxillary nerve between different untrained anesthetists. This was a prospective, randomized, blinded study, performed in 40 heads obtained from feline cadavers. Three veterinarians (A, B and C) with no previous experience with the IO approach performed the experiments. The SBZ approach was randomly performed on one side of the head and the IO approach was performed in the contralateral side of the same head. For each approach, 0.2ml of 1% methylene blue dye was injected. Scores for length of nerve staining were as follows: 0 (failure), no staining; 1 (moderate), <6mm of nerve stained; and 2 (ideal), ≥6mm of nerve stained. Median scores (interquartile range) for the SBZ and IO approaches were 2.0 (0.3-2.0) and 1.0 (0.0-2.0), respectively. Scores for length of nerve staining were higher with the SBZ approach than the IO approach (P=0.016). Considering the scores for both the SBZ and IO approaches, there was a significant difference among the three veterinarians (P=0.002). Results of this study do not support the IO approach to perform a maxillary nerve block in cats. A greater accuracy of methylene blue dye placement was observed with the SBZ approach. A variable accuracy may exist between different veterinarians when performing a maxillary nerve block employing the SBZ and IO techniques in cats.O objetivo deste estudo foi comparar o acesso do nervo maxilar pela abordagem subzigomática (SBZ) com a abordagem pelo forame infraorbitário (IO) em peças anatômicas de gatos utilizando o corante azul de metileno. Um segundo objetivo foi comparar a acurácia na coloração do nervo maxilar com o azul de metileno entre diferentes anestesistas que não receberam treinamento prévio. Este estudo foi prospectivo, randomizado, cego, realizado em 40 peças anatômicas de cabeças de gatos. Três veterinários (A, B e C), sem experiência prévia da abordagem IO, realizaram o experimento. A abordagem SBZ foi aleatoriamente realizada em um dos lados da cabeça e a abordagem IO foi realizada no lado contralateral da mesma peça anatômica. Para cada abordagem, utilizou-se 0,2mL do corante azul de metileno 1%. Classificou-se o escore de coloração baseado no comprimento do nervo maxilar corado pelo azul de metileno conforme a escala: 0 (falha da técnica), sem coloração; 1 (moderado), <6mm de coloração do nervo maxilar; 2 (ideal), ≥6mm de coloração do nervo maxilar. As medianas (intervalo interquartil) para as abordagens SBZ e IO (dados de todos os veterinários juntos) foram respectivamente 2,0 (0,3-2,0) e 1,0 (0,0-2,0). A abordagem SBZ foi associada a um escore de coloração, significativamente, maior do que a abordagem IO (P=0,016). Considerando os escores de ambas abordagens (SBZ e IO), houve diferença significativa nos escores de coloração do nervo maxilar entre os três veterinários anestesistas (P=0,002). Os resultados deste estudo não sustentam a utilização da abordagem IO para a realização do bloqueio maxilar em gatos. Uma melhor acurácia na coloração do nervo maxilar com o azul de metileno foi observada com a abordagem SBZ. A acurácia da técnica pode variar quando as abordagens SBZ e IO são realizadas por veterinários diferentes, com o objetivo de se obter o bloqueio do nervo maxila