High Definition Oscillometry Research Articles

Pulse-wave analysis during routine blood pressure measurement shows potential to distinguish between sinus and nonsinus rhythm.

To investigate whether pulse-wave analysis (PWA) performed by trained evaluators facilitates detection of nonsinus rhythm. Same-day, high-definition oscillometry pulse-wave data and ECG results of 155 animals (144 dogs and 11 cats) were analyzed. In this cross-sectional study, we enrolled 18 participants from various backgrounds, all of whom received PWA training. The ability to distinguish between sinus and nonsinus rhythms was assessed using receiver operating characteristic curve analysis. The pulse-wave datasets were divided into 5 ECG categories. Agreement between ECG diagnoses and PWA-based arrhythmia detection was evaluated using Cohen κ values, and the correlation between the academic year of veterinary students and their κ values was assessed. All cardiology researchers demonstrated satisfactory accuracy in distinguishing pathological rhythms using PWA (area under the curve, 0.704 to 0.761), with the highest accuracy in detecting atrial fibrillation (area under the curve, 0.811 to 0.845). Fair agreement with ECG categorization was achieved by all 3 cardiology researchers, 2 of 5 general practitioners, and 3 of 10 veterinary undergraduates. The veterinary undergraduates' years of study were correlated with their diagnostic performance (Spearman ρ = 0.658; P = .019). PWA during routine noninvasive blood pressure measurement showed significant potential for the detection of pathological arrhythmias, notably atrial fibrillation. This approach yielded improved effectiveness when it was used by veterinarians with cardiology experience. Thus, introducing hands-on training courses, particularly those focused on cardiology and interactive workshops, may enable frontline veterinarians to promptly identify arrhythmias using PWA, facilitating timely ECG examinations or referrals.

Comparison of Doppler ultrasonic sphygmomanometry, oscillometry and high-definition oscillometry for non-invasive blood pressure measurement in conscious cats.

Systemic arterial hypertension is a common occurrence and can have serious adverse consequences in cats. Therefore, measuring blood pressure is very important. There are many indirect blood pressure measurement devices available. This study compared Doppler, oscillometric (petMAP Graphic II, SunTech Vet20, the Cardell Insight-X0000) and high-definition oscillometry devices for the non-invasive measurement of blood pressure in conscious cats. In this prospective study, blood pressure was measured in 32 cats using the different devices according to the recommendations of the American College of Veterinary Internal Medicine Consensus Statement. Blood pressures (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP]), time to complete measurements, number of attempts needed, coefficient of variation (CV) between the blood pressure measurements of the different devices, ease of completing measurements and apparent stress level of the cat were assessed. There was a significant difference between devices in the time taken to obtain blood pressure readings and the number of attempts necessary to obtain six reliable measurements. The CV of the Doppler device was significantly smaller than that of the rest of the devices, but there were no other differences between the devices. The mean SBP, DBP and MAP measured by the petMAP device were significantly higher than the measurements from the other devices. The perceived ease of measurement was not significantly different between the various machines. The perceived level of stress of measurement with the Doppler device was significantly higher compared with the other devices but did not lead to an increased SBP. Using a Doppler device to measure blood pressure in conscious cats is fast, relatively easy and gives reliable results. A disadvantage is that the Doppler device can only measure SBP, while oscillometric devices also provide DBP and MAP. However, in veterinary medicine, systolic hypertension is considered the most relevant.

Systolic blood pressure measurements with Doppler ultrasonic flow detector and high-definition oscillometry are comparable on population level but show large intra-individual differences in apparently healthy elderly dogs.

Agreement of systolic blood pressure measurements (SBP) between noninvasive blood pressure devices in conscious dogs is poorly studied. Situational hypertension is expected in clinics, but studies are lacking. This study aimed to compare SBP measurements obtained with Doppler ultrasonic flow detector (Doppler) versus high-definition oscillometry (HDO) in clinics and at home and to estimate the prevalence of situational hypertension in conscious, apparently healthy elderly dogs. 122 apparently healthy elderly or geriatric dogs were prospectively recruited. Systolic blood pressure was obtained consecutively with Doppler and HDO techniques in a randomized order per dog, following a standardized protocol. An at-home measurement was advised for in-clinic hypertensive dogs (SBP ≥ 160 mmHg), also using both devices. Dual measurements were available in 102 dogs. Median SBP was 147.3 mmHg (range, 105 to 239 mmHg) for Doppler and 152.3 mmHg (range, 113 to 221 mmHg) for HDO. Forty-six percent (56/122) were hypertensive, of which 9% (11/122) were hypertensive with both methods. No significant difference was found between the 2 devices in the global study population or within the group of hypertensive dogs. Repeated at-home measurements were performed in 20/56 (35.7%) hypertensive dogs, resulting in a 10 and 26 mmHg lower median SBP value for Doppler and HDO, respectively (P > .05). In-clinic situational hypertension was presumed in 8/20 (40%) dogs. The choice of the noninvasive blood pressure device did not significantly impact SBP results, but large interindividual differences in SBP between techniques occurred. Situational hypertension was frequently observed in clinic.

Agreement of high-definition oscillometry at two cuff locations with invasively measured arterial blood pressures in anaesthetised cheetahs

ObjectivesTo evaluate the agreement between high-definition oscillometry (HDO) used on the metatarsus or tail base with invasive arterial blood pressures measured in the dorsal pedal artery in anaesthetised cheetahs. Study DesignProspective clinical study. AnimalsA group of 13 captive adult cheetahs. MethodsCheetahs were immobilised with medetomidine (32–45 μg kg–1) and tiletamine/zolazepam (0.93–1.39 mg kg–1) administered intramuscularly, and anaesthesia was maintained with either isoflurane in oxygen or continuous propofol infusion. Invasive blood pressure was measured via a 20 gauge intra-arterial catheter in the dorsal pedal artery in the metatarsus and used as a reference method for pressures simultaneously estimated using HDO on the contralateral metatarsus and tail base. Bland–Altman plots (for repeated measurements) and criteria defined by the American College of Veterinary Internal Medicine (ACVIM) were used to compare agreement according to the anatomical location of the cuff, the anaesthetic maintenance agent and magnitude of the blood pressure. ResultsA total of 147 paired measurements were obtained with HDO on the metatarsus and 135 on the tail. Agreement with invasive pressures was better when HDO was used on the tail (rather than on the metatarsus) with all ACVIM criteria being met. Mean bias (a positive bias meaning that HDO overestimated the invasively measured pressures) ± standard deviation of differences for systolic, diastolic and mean arterial pressures were –7.0 ± 13.9, 4.2 ±12.1 and 4.6 ±11.2 mmHg, respectively, for HDO on the tail, and –11.9 ±15.1, 2.8 ±16.5 and 2.1 ±13.2 mmHg, respectively, for HDO on the metatarsus. Agreement was better during isoflurane anaesthesia than propofol, and at lower blood pressures than at higher. Conclusions and clinical relevanceWhen used on the tail base of anaesthetised cheetahs, HDO met the ACVIM validation criteria for a noninvasive device, as compared to invasively measured pressures in the dorsal pedal artery.

A Pilot Assessment of Inosine Effects on Blood Pressure in Vervet Monkeys

ObjectivesInosine, a purine metabolite, has been shown to have anti-inflammatory and cardioprotective effects. Studies in rodent models have shown conflicting effects of inosine on blood pressure, a key risk factor for cardiovascular disease (CVD). Vervet monkeys (Chlorocebus aethiops sabaeus) are genetically and physiologically similar to humans. Thus, they are excellent models to study CVD or related risk factors. Our aim in this pilot study was to determine the effects of inosine on blood pressure in in a cohort of 16 Vervet monkeys. MethodsEight monkeys (50% female) were randomly assigned to be orally gavaged 250 mg/kg of inosine (mixed in Ensure® nutrition shake) for 7 days while the other eight (50% female) were given just the nutrition shake (control). Anthropometric and biochemical measures were obtained at baseline, post-treatment (7 days) and post-wash out period (14 days). Blood pressure was measured using high definition Oscillometry at both time points. Statistical analysis was conducted using STATA (Stata/BE 17.0). ResultsAt baseline, males had higher body weight than females (7.86 ±1.1 vs. 5.95 ± 1.2 kg, p = 0.005) whereas blood pressure and waist circumference were not significantly different between them. There was a significant decrease in body weight in females (–0.26±0.05 kg, p < 0.02) in the treatment group as compared to males (0.14±0.06 kg) or females in the control group (0.16 ± 0.06 kg). Sex-specific changes in systolic blood pressure were also observed. Systolic blood pressure increased in control group as compared to the treatment group (20 ± 6.6 mmHg vs. 6.8 ±2.8 mmHg, p < 0.06, respectively) in males and (10.1 ± 5.5 mmHg vs. 1.3±17 mmHg, p = .16, respectively) in females. Similar results were found for mean arterial pressure. Changes in waist circumference or diastolic blood pressure were not significantly different either between sexes or treatment groups. ConclusionsResults of this pilot study are promising as inosine seems to have a stronger effect on body weight and systolic blood pressure as compared to the control group. However, more in-depth investigations are required to confirm and validate these initial findings. Funding SourcesA pilot grant from Nutrition Research Institute, University of North Carolina at Chapel Hill to VSV.

Use of a human wrist blood pressure monitor for arterial blood pressure measurements in normotensive conscious dogs in comparison to veterinary high-definition oscillometry.

BackgroundThe gold standard in canine blood pressure (BP) measurement is the invasive method; however, non‐invasive blood pressure measurement techniques (NIBP) are more commonly used. The lack of small, lightweight, cheap, fast and portable NIBP still remains a point to improve in the emergency setting.Key FindingsA human wrist blood pressure (WBP) device was evaluated in comparison with the veterinary high‐definition oscillometry (HDO) in conscious normotensive dogs. Systolic and diastolic BPs were evaluated in two groups of dogs. The bias, the limits of agreement and correlation between variables were calculated. Twenty‐five and 36 dogs were, respectively, included in Study No. 1 (dogs weighting ≥10 kg) and 2 (dogs weighting ≥20 kg). In both studies, correlation between the two devices was moderate. A better agreement was displayed for diastolic pressure and poor precision for both systolic and diastolic pressures measurements (as determined by wide limits of agreement). The WBP method underestimated both the systolic and diastolic BP with respect to the HDO method. The inclusion of bigger dogs (Study No. 2) with limb circumference more like to human limb dimension did not improve the agreement between considered methods.SignificanceThe human WBP monitor considered is not suitable to replace the commonly used veterinary HDO for in‐clinic BP monitoring in normotensive conscious dogs.

Agreement of High-Definition Oscillometry (HDO) and Invasive Blood Pressure Measurements at a Metatarsal Artery in Isoflurane-Anaesthetised Horses.

Simple SummaryIn equine anaesthesia, valid and reliable blood pressure monitoring is crucial for adequate blood pressure management. Various non-invasive blood pressure monitors have been studied with varying results. High-definition oscillometry (HDO) promises greater accuracy than conventional oscillometric devices. With the cuff placed at the tail, the monitor gives satisfactory readings in normotensive anaesthetised horses, while for measuring low and high blood pressure, reliability was inadequate. To date, high-definition oscillometry has not been evaluated at the easily accessible equine metatarsal area. Therefore, the objective of this study was to assess agreement between HDO and invasive blood pressure, both obtained at a metatarsal artery at different blood pressure ranges in anaesthetised horses. Additionally, compliance with the American College of Veterinary Internal Medicine consensus guidelines was assessed. Agreement of HDO and invasive blood pressure was acceptable for mean arterial blood pressure during normotension only. During hypotension and hypertension, measurements were not valid. The monitor failed to meet most of the consensus validation criteria. Consequently, invasive blood pressure measurement remains preferable in haemodynamically unstable patients.High-definition oscillometry (HDO) over the metatarsal artery (MA) in anaesthetised horses has not yet been evaluated. This study aimed to assess agreement between HDO and invasive blood pressure (IBP) at the metatarsal artery, and to evaluate compliance with the American College of Veterinary Internal Medicine (ACVIM) consensus guidelines. In this experimental study, 11 horses underwent general anaesthesia for an unrelated, terminal surgical trial. Instrumentation included an IBP catheter in one and an HDO cuff placed over the contralateral MA, as well as thermodilution catheters. Systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), and cardiac output were measured simultaneously. Normotension (MAP 61–119 mmHg) was maintained during the surgical study. Subsequently, hypotension (MAP ≤ 60 mmHg) and hypertension (MAP ≥ 120 mmHg) were induced pharmacologically. For MAP, the agreement between HDO and IBP was acceptable during normotension, while during hypotension and hypertension, IBP was overestimated and underestimated by HDO, respectively. The monitor failed to meet most ACVIM validation criteria. Consequently, if haemodynamic compromise or rapid blood pressure changes are anticipated, IBP remains preferable.

Influence of clinical setting and cat characteristics on indirectly measured blood pressure and pulse rate in healthy Birman, Norwegian Forest, and Domestic Shorthair cats.

BackgroundMeasured indirect blood pressure (BP) results in cats in a clinical environment might be affected by stress and characteristics of the cats.HypothesisTo investigate the influence of clinical setting, cat characteristics, and life situation on BP and pulse rate (PR) in healthy cats.AnimalsNinety‐four healthy Domestic Shorthair, Birman and Norwegian Forest cats.MethodsBlood pressure measured by high‐definition oscillometry in 3 settings: cat placed in its own carrier with veterinarian present; cat placed in carrier with owner alone present; and cat placed on table with veterinarian present. Statistical analyses were performed using mixed linear models.ResultsSystolic BP (SBP) did not differ among settings. Higher mean arterial pressure (MAP), diastolic BP (DBP), and PR were found when measurements were performed with cat placed on table, rather than in carrier. Coefficients of variation (CVs) higher for SBP, MAP, DBP, and PR when measured with cat placed on table than in carrier. Birman cats had lower BP than other breeds. Systolic BP, MAP, DBP, and PR increased with age. Cats allowed outdoors had lower PR than cats living strictly indoors.Conclusion and Clinical ImportanceNo difference in SBP was found among settings, but measuring BP with the cat placed on the examination table gave higher MAP, DBP, PR, and CV than measuring BP with the cat in its carrier. Breed affected BP, with lower BP in Birman cats than other breeds. Blood pressure increased with age. Pulse rate was lower in cats allowed outdoors than cats living strictly indoors.

Physical rehabilitation in idiopathic paroxysmal atrial fibrillation

Physical rehabilitation a promising approach in the treatment of idiopathic paroxysmal atrial fibrillation which is a important medical problem. Study objective : To develop and scientifically substantiate reflexology and physical training methods for the treatment and prevention of regulatory functional cardiac disorders in idiopathic paroxysmal atrial fibrillation. Materials and methods . The study involved 90 patients with idiopathic atrial fibrillation (IAF), who were divided into 2 groups: 45 patients with adrenergic (AAFF) and 45 patients with vagotonic (VAFF) forms. The patients received a complex treatment consisting of reflexology and dosed walking. The treatment efficacy evaluation involved clinical, functional and instrumental examinations, psychological tests, psychophysiological stress-test, 24h ECG monitoring to identify the standard deviation of the normal-to-normal RR intervals (SDNN); echocardiography, high-definition oscillometry, and biochemical tests. Results . We found that the complex of reflexology and dosed walking in both groups produced an antiarrhythmic effect resulting in reliable normalization of the cardiovascular system autonomic regulation. Conclusions . The complex normalizes the heart rate autonomic regulation and hemodynamic parameters, improves the psychological and emotional state and the quality of life. The proposed treatment demonstrated high efficiency.

Plasma homocysteine in a non-rodent model of cardiovascular diseases: Establishment of a reference interval and assessment of biological variations in cats

Cats are a relevant small animal model for several spontaneous cardiovascular diseases, such as hypertrophic cardiomyopathy and systemic hypertension. In people, homocysteine is an independent risk factor for cardiovascular diseases. Cats are obligate carnivores and have numerous metabolic peculiarities that may predispose them to alterations of homocysteine. The purpose of this study was to determine a reference interval and to assess biological variations for plasma homocysteine in healthy privately-owned cats. All participating cats underwent a complete physical examination, urinalysis and blood testing to rule out any signs of disease. Systemic arterial blood pressure was measured by use of high-definition oscillometry. Plasma homocysteine was measured in healthy cats with a high-performance liquid chromatography – tandem mass spectrometry method. Of 111 cats evaluated, 4 cats showed at least one significant abnormality on physical examination and 16 cats were not included due to a fractious behavior. Ninety-one cats completed the study and 14 of them were excluded due to at least one significant abnormality on blood work or urinalysis. The nonparametric reference interval for plasma homocysteine in 77 healthy cats was 6.1–52.8 μmol/L. There was no influence of the breed, age, sex and body condition score. The reference interval for plasma homocysteine is much wider in the feline population than in humans. Contrary to what is described in people, plasma homocysteine in cats is not higher in males than in females and does not increase with age. The role of environmental factors, such as dietary considerations, on plasma homocysteine will be studied. The impact of plasma homocysteine on systemic arterial blood pressure will also be discussed.

Non-invasive blood pressure measurement in ferrets (Mustela putorius furo) using high definition oscillometry

This study was conducted to validate the use of high definition oscillometry (HDO) for non-invasive blood pressure (NIBP) measurements in ferrets and to establish reference ranges for NIBP in minimally sedated, healthy, young adult ferrets (<4years of age). The bias, limits of agreement and correlation for HDO compared to direct arterial blood pressure (DABP) measurement were established in 14 anaesthetised ferrets. Measurements were performed at the forelimb, hind limb and tail under hypo- (<110mmHg), normo- (110–170mmHg) and hypertensive (>170mmHg) conditions. Although HDO correlated well with DABP (r>0.90), it showed significant proportional bias, whereby HDO generally underestimated DABP with hyper- and normotensive conditions, and overestimated DABP with hypotensive conditions. Measurements obtained from the hind limb showed higher bias than those obtained from the tail or forelimb (P<0.001). Based on the above, and for practical reasons, the tail was selected as the preferred site of cuff placement in ferrets. Subsequently, a cross-over study was performed in 10 ferrets to establish the minimum dose of butorphanol and midazolam needed to successfully obtain NIBP in 100% of cases. Using this dose (0.2mg/kg IM, each), reference intervals for NIBP from 63 healthy, young adult ferrets were established at 95–155mmHg (systolic), 69–109mmHg (mean) and 51–87mmHg (diastolic) arterial pressures.

The effect of anesthetic drug choice on accuracy of high-definition oscillometry in laterally recumbent horses

ObjectiveTo determine the accuracy of high-definition oscillometry (HDO) for arterial pressure measurement during injectable or inhalation anesthesia in horses. Study designProspective, clinical study. AnimalsTwenty-four horses anesthetized for procedures requiring lateral recumbency. MethodsHorses were premedicated with xylazine, and anesthesia induced with diazepam–ketamine. Anesthesia was maintained with xylazine–ketamine–guaifenesin combination [TripleDrip (TD; n = 12) or isoflurane (ISO; n = 12)]. HDO was used to obtain systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, and heart rate (HR) using an 8-cm-wide cuff around the proximal tail. Invasive blood pressure (IBP), SAP, MAP, DAP and HR were recorded during HDO cycling. Bland–Altman analysis for repeated measures was used to compare HDO and IBP for all measurements. The generalized additive model was used to determine if means in the differences between HDO and IBP were similar between anesthetic protocols for all measurements. ResultsThere were >110 paired samples for each variable. There was no effect of anesthetic choice on HDO performance, but more variability was present in TD compared with ISO. Skewed data required log-transformation for statistical comparison. Using raw data and standard Bland–Altman analysis, HDO overestimated SAP (TD, 3.8 ± 28.3 mmHg; ISO, 3.5 ± 13.6 mmHg), MAP (TD, 4.0 ± 23.3 mmHg; ISO, 6.3 ± 10.0 mmHg) and DAP (TD, 4.0 ± 21.2 mmHg; ISO, 7.8 ± 13.6 mmHg). In TD, 26–40% HDO measurements were within 10 mmHg of IBP, compared with 60–74% in ISO. Differences between HDO and IBP for all measurements were similar between anesthetic protocols. The numerical difference between IBP and HDO measurements for SAP, MAP and DAP significantly decreased as cuff width:tail girth ratio increased toward 40%. Conclusion and clinical relevanceMore variability in HDO occurred during TD. The cuff width:tail girth ratio is important for accuracy of HDO.

Die systemische Hypertension bei der Katze – Diagnostik und Behandlung

Systemic is a common medical condition in older cats, which is mostly caused by an underlying disease such as chronic kidney disease, hyperthyroidism, diabetes mellitus (predominantly diastolic hypertension) or hyperaldosteronism. Target organ damage can occur if the blood pressure is elevated. Affected organs are the eye, kidney, brain and heart. If the blood pressure exceeds 180/120 mmHg there is a high risk for the development of target organ damage. Whenever a disease with a high prevalence of is diagnosed or target organ damage is suspected, measurement of blood pressure should be performed. Indirect techniques to measure blood pressure are the Doppler sonography and the high definition oscillometry (HDO). A reliable assessment of the blood pressure can be achieved if a standardized protocol is followed. Especially the problem of ,,white coat hypertension should be eliminated. If is diagnosed, further decisions will be made based on the severity of the and possible target organ damage. If the latter is present, medical therapy should be immediately started. If target organ damage is absent, blood pressure measurement is at first repeated to verify hypertension. The first choice medical agent is independent of the causative disease amlodipin. The treatment goal is to permanently lower the blood pressure to < 160/100 mmHg. With this approach the development of progression of target organ damage can be prevented. In most cases of affected cats, systemic and the causative disease have to be treated and monitored lifelong.

Systolic arterial blood pressure estimated by mitral regurgitation velocity, high definition oscillometry, and Doppler ultrasonography in dogs with naturally occurring degenerative mitral valve disease

IntroductionTo determine if systolic blood pressure estimated by mitral regurgitation (MR) velocity can be used interchangeably with that estimated by high definition oscillometry (HDO) and Doppler ultrasonography (DU) in dogs with naturally occurring mitral valve disease (MVD). AnimalsForty-nine client-owned dogs with naturally occurring MVD. Materials and MethodsThis is a retrospective study. Medical records were reviewed and dogs with MR caused by degenerative MVD were included if systolic blood pressure was estimated from MR velocity determined by continuous wave Doppler (CW), DU and HDO at the same visit. A Pearson product moment correlation coefficient was determined for each combination of measures and tested for significance with a paired t-test. Limits of agreement between 2 measures were determined by the 95% confidence interval of the average difference of the means and illustrated by Bland–Altman plots. ResultsSystolic pressure estimated from CW was significantly but only moderately correlated to DU (r = 0.42, p=0.0015) and HDO (r = 0.40, p=0.0021). Pressure estimated from DU was significantly but only moderately correlated to HDO (r = 0.57, p≤0.0001). Limits of agreement were wide for all measures including DU and CW (−61.9to 44.6 mmHg), HDO and CW (−65.2to 26.9 mmHg), and HDO and DU (−63.1 to 42.06 mmHg). DiscussionSystolic blood pressure estimated by CW cannot be used interchangeably with HDO or DU in dogs with naturally occurring MVD.

COMPARISON OF HIGH-DEFINITION OSCILLOMETRIC AND DIRECT ARTERIAL BLOOD PRESSURE MEASUREMENT IN ANESTHETIZED CHEETAHS (ACINONYX JUBATUS).

Blood pressure measurement reveals important insights into the health of conscious and anesthetized individuals. This is of particular interest in cheetahs (Acinonyx jubatus), which in captivity are known to suffer from chronic diseases that may be associated with hypertension and which often require immobilization for transport or veterinary treatment. Invasive testing methods are considered the gold standard but are not practical in many settings. Consequently, it is important to evaluate the use of noninvasive methods in this species. Measurements for systolic, diastolic, and mean arterial pressure obtained using high-definition oscillometry (HDO) at the coccygeal artery were compared to simultaneous direct measurements obtained via catheterization of the femoral or dorsal pedal artery in eight anesthetized captive cheetahs during nine anesthetic events. Overall, HDO and direct measurements agreed most closely for mean arterial pressure, and the poorest agreement was observed for systolic pressure. There was a tendency for low diastolic pressures to be underestimated and for high diastolic pressures to be overestimated. Across all three parameters, HDO measurements from the tail overestimated directly measured pressures in the femoral artery and underestimated those in the dorsal pedal artery. HDO agreed most closely with directly measured dorsal pedal pressures. Mean arterial pressure showed the greatest precision (standard deviation of 10.2 mm Hg) and lowest bias (-1.2 mm Hg), with 75.9% of readings within 10 mm Hg of the direct dorsal pedal pressure. Agreement with systolic pressure was hindered by a high bias (-10.4 mm Hg), but if a correction factor of +10 mm Hg was applied to all systolic measurements, agreement was improved and 65.7% of readings were within 10 mm Hg of the direct pressure. When compared to criteria defined by the American College of Veterinary Internal Medicine for validation of blood pressure devices, results were favorable, but a limited sample size prevented formal validation.

Agreement of high definition oscillometry with direct arterial blood pressure measurement at different blood pressure ranges in horses under general anaesthesia

ObjectiveTo determine the agreement of high definition oscillometry (HDO) with direct arterial blood pressure measurements in normotensive, hypotensive and hypertensive horses during general anaesthesia. Study designExperimental study. AnimalsSeven healthy warmblood horses, aged 3–11 years, weighing 470–565 kg. MethodsMeasurements from a HDO device with the cuff placed around the base of the tail were compared with pressures measured invasively from the facial artery. High blood pressures were induced by intravenous (IV) administration of dobutamine (5 μg kg−1 minute−1) over ten minutes followed by norepinephrine (0.1 mg kg−1 IV) and low pressures by increasing the inspired fraction of isoflurane and administration of nitroglycerine (0.05 mg kg−1 IV). For analysis three pressure levels were determined: high (MAP>110 mmHg), normal (60 mmHg<MAP<110 mmHg) and low (MAP< 60 mmHg). Bland-Altman analysis was used for comparison between non-invasive and invasive measurements. ResultsA total of 245 paired measurements of systolic (SAP), mean (MAP) and diastolic (DAP) pressures were obtained. The HDO device underestimated blood pressure at hypertensive and normotensive levels and overestimated blood pressure at hypotensive levels. Best agreement was obtained for SAP and MAP within normotensive limits. At normotension, bias ± standard deviation for SAP, MAP and DAP were 0.1 ± 19.4 mmHg, 0.5 ± 14.0, 4.7 ± 15.6, respectively. At high pressure levels bias and SD were 26.1 ± 37.3 (SAP), 4.2 ± 19.4 (MAP), 1.5 ± 16.8 (DAP) and at low pressures -20.0 ± 20.9 (SAP), -11.4 ± 19.6 (MAP), -4.7 ± 20.1 (DAP), with HDO measurements at a MAP <50 mmHg often failing. Conclusion and clinical relevanceGood agreement with invasive arterial blood pressures was obtained with HDO at normotensive levels in horses. At high and low pressure ranges HDO was unreliable. Therefore, if haemodynamic instability is expected, invasive measurement remains preferable.

Randomized placebo-controlled clinical trial of a chewable formulation of amlodipine for the treatment of hypertension in client-owned cats.

BackgroundThere is an unmet clinical need for a cat‐specific formulation of amlodipine to treat hypertensive cats.ObjectivesTo assess the efficacy of chewable amlodipine tablets in reducing systolic blood pressure (SBP) in cats diagnosed with systemic arterial hypertension.AnimalsSeventy‐seven client‐owned cats with systemic hypertension were included (median age 14 years).MethodsThe study was randomized, double‐blinded, and placebo‐controlled. Forty‐two cats received 0.125–0.50 mg/kg amlodipine once daily for 28 days; 35 cats received placebo. After 28 days all cats continued with amlodipine for 2–3 months in an open‐label phase. Blood pressure was measured using high definition oscillometry. A responder was defined as a cat showing a decrease of SBP to <150 mmHg at 28 days or a decrease from baseline ≥15%.ResultsSixty‐one cats completed the study. The responder rate was 63% in amlodipine group and 18% in placebo group. Cats receiving amlodipine were 7.9 (95% CI 2.6–24.1) times more likely to be classified as responders when compared to those receiving placebo (P < .001). From a mean (±SD) baseline value of 181 (±12) mmHg, SBP decreased to 154 (±17) mmHg with amlodipine and to 170 (±21) mmHg with placebo (P < .001). The voluntary acceptance rate of amlodipine formulation was 73%.Conclusions and Clinical ImportanceThe chewable amlodipine tablet effectively reduced SBP compared with placebo in hypertensive cats, and was well‐tolerated. It can be used concomitantly with angiotensin‐converting enzyme inhibitors and in cats with chronic kidney disease.

High Definition Oscillometry: Non-invasive Blood Pressure Measurement and Pulse Wave Analysis.

Non-invasive monitoring of blood pressure has become increasingly important in research. High-Definition Oscillometry (HDO) delivers not only accurate, reproducible and thus reliable blood pressure but also visualises the pulse waves on screen. This allows for on-screen feedback in real time on data validity but even more on additional parameters like systemic vascular resistance (SVR), stroke volume (SV), stroke volume variances (SVV), rhythm and dysrhythmia. Since complex information on drug effects are delivered within a short period of time, almost stress-free and visible in real time, it makes HDO a valuable technology in safety pharmacology and toxicology within a variety of fields like but not limited to cardiovascular, renal or metabolic research.

Non-invasive blood pressure measurement: values, problems and applicability in the common marmoset (Callithrix jacchus).

The common marmoset (Callithrix jacchus, C. j.) is an established primate model in biomedical research and for human-related diseases. Monitoring of cardiovascular parameters including blood pressure (BP) is important for the health surveillance of these experimental animals and the quantification of diseases or pharmaceutical substances influencing BP. Measurement guidelines for C. j. do not exist yet; therefore, the present study was carried out to establish a practicable protocol based on recommendations of the American College of Veterinary Internal Medicine (ACVIM). Furthermore, BP data of 49 marmosets (13.8-202.4 months of age) were obtained via high-definition oscillometry to further knowledge of physiological parameters and gender-related differences in this primate. The thighs proved to be the most suitable measurement localization, since systolic values were less variable (left 4.03 ± 2.90%, right 5.96 ± 2.77%) compared with the tail (12.7 ± 6.96%). BP values were similar in the morning and in the afternoon (P > 0.05). Data were highly reproducible within and between several sessions on three consecutive days (P > 0.05) as well as over the course of 20 months (P > 0.05). Furthermore, the measurement time for females was significantly shorter than for males (5:14 ± 1:59 min versus 6:50 ± 1:58 min, P = 0.007). Measurement recommendations for the common marmoset were successfully established. Standardized values enabled a reliable comparison of BP parameters, e.g. for cardiovascular, toxicological or metabolic research.

Comparison of HDO® (high definition oscillometry), a novel noninvasive technology for arterial blood pressure measurement, to a direct invasive method using radiotelemetric equipment in awake healthy cats

Comparison of HDO® (high definition oscillometry), a novel noninvasive technology for arterial blood pressure measurement, to a direct invasive method using radiotelemetric equipment in awake healthy cats