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

Evaluation of the accuracy of the Delta Life DL 1000 oscillometric monitor for blood pressure measurement in anesthetized dogs of different weight ranges

Background: Arterial blood pressure is one of the most commonly variables monitored during anesthetic procedures in veterinary patients. The most reliable method for measuring arterial blood pressure in dogs and cats is the direct (invasive) method. However, the oscillometric method is less complex and more practical for clinical routine in small animals. Nevertheless, oscillometric monitors present great variability in accuracy. The present study aimed to determine the accuracy of the Delta Life DL 1000 oscillometric monitor for measurement of systolic, mean and diastolic blood pressures (SAP, MAP and DAP, respectively) in anesthetized dogs of different weight ranges. Materials, Methods & Results: This study was approved by the Institutional Ethics Committee of Animal Use. Fifteen female dogs of different breeds, weighing 11.6 ± 10.0 kg and with a mean age of 48 ± 51 months were used. All animals were scheduled for elective surgery under general anesthesia in the Institution Veterinary Hospital. Dogs were anesthetized with morphine, propofol and isoflurane and had a 20 or 22 gauge catheter introduced into the dorsal pedal artery for continuous, invasive monitoring of SAP, MAP and DAP. A blood pressure cuff was positioned over the middle third of the radius and connected to Delta Life DL 1000 monitor. Oscillometric readings of SAP, MAP and DAP were registered every 5 minutes, and invasive values were simultaneously recorded. Values obtained with both methods were compared (invasive versus oscillometric) by use of the Bland Altman method to determine the bias, standard deviation of bias and 95% limits of agreement. The percentages of errors between the methods within 10 mmHg and within 20 mmHg were calculated. The results obtained were compared with the criteria from the American College of Veterinary Internal Medicine (ACVIM) for validation of indirect methods of arterial blood pressure measurement. Data were stratified into two groups according to the weight: 140 mmHg). Bias (± SD) values in Group 1 were as follows: SAP, 5.2 ± 18.1 mmHg; MAP, -3.4 ± 17.2 mmHg; and DAP, 12.0 ± 17.5 mmHg. The percentages of errors within 10 mmHg were 40.3% for SAP; 45.4% for MAP and 28.6% for DAP. The percentages of errors within 20 mmHg were 72.3% for SAP, 84.0% for MAP and 68.1% for DAP. In Group 2, 66 paired measurements were obtained, nine of which classified as hypotension, 56 as normotension and one as hypertension. Bias (± SD) in Group 2 were as follows: SAP, 13.6 ± 14.3 mmHg; MAP, -1.1 ± 13.5 mmHg; and DAP, 8.2 ± 16.0 mmHg. The percentages of errors within 10 mmHg were 33.3% for SAP, 77.3% for MAP and 33.3% for DAP. The percentages of errors within 20 mmHg were 65.1% for SAP, 92.4% for MAP and 83.4% for DAP. Discussion: Based on the results of this study and reference criteria from the ACVIM, the Delta Life DL 1000 monitor had a poor accuracy for SAP, MAP and DAP and did not meet the criteria from the ACVIM in anesthetized dogs under 10 kg. Measurements of MAP in dogs ≥ 10 kg met the ACVIM criteria, but measurements of SAP and DAP did not. Based on the findings in this study, the DL 1000 oscillometric monitor is not recommended for blood pressure measurement in anesthetized dogs < 10 kg. In dogs ≥ 10 kg, measurements of MAP yielded acceptable values, but SAP and DAP measurements did not