Non-invasive Blood Pressure Measurement Technique Research Articles

Effects of pre-electroacupuncture on blood pressure and cardiac function in high-salt-induced hypertension rats

To observe the effects of pre-electroacupuncture at "Taichong"(LR3), "Neiguan"(PC6) and "Waiguan"(TE5) on blood pressure and cardiac function of high-salt-induced hypertension rats, so as to explore the possible mechanism of pre-electroacupuncture in improving hypertension. Twenty-four SD rats were randomly divided into control group, high-salt group and pre-electroacupuncture group, with 8 rats in each group. The hypertension model was established by feeding high-salt diet for 7 weeks. In the pre-electroacupuncture group, rats received electroacupuncture intervention at bilate-ral LR3, PC6 and TE5 (2 Hz/15 Hz, 2 mA) for 30 min, once a day, from the first day of modeling, for a total of 7 weeks. The blood pressure of rats was monitored by caudal artery noninvasive blood pressure measurement technique before and at the 1st, 3rd, 5th and 7th week of modeling. At the 8th week of the experiment, left ventricular catheterization was performed and biological signal acquisition system was used to detect left ventricular hemodynamics indexes and analyze left ventricular function, the car-diac mass ratio was measured to evaluate the degree of myocardial hypertrophy. The mRNA expressions of atrial natriuretic peptide(ANP), myosin heavy chain 7(MYH7), α-smooth muscle actin(α-SMA), interleukin(IL)-1β, and IL-6 of myocardial tissues were detected by quantitative real-time PCR. Sirius red staining was used to observe the degree of myocardial fibrosis. Compared with the control group, systolic blood pressure, diastolic blood pressure, mean arterial pressure, left ventricular end-diastolic pressure (LVEDP), cardiac mass ratio，and the mRNA expressions of ANP, MYH7, α-SMA, IL-1β, and IL-6, and sirius red staining area of myocardium were all significantly increased(P<0.01,P<0.05)，maximal rate of rise and descent of left ventricular pressure(LVP±dP/dtmax) were decreased (P<0.05,P<0.01) in the high-salt group. Compared with the high-salt group, rats in the pre-electroacupuncture group had lower systolic blood pressure, diastolic blood pressure, mean arterial pressure, LVEDP，cardiac mass ratio，higher LVP±dP/dtmax,down-regulated mRNA expressions of ANP, MYH7, α-SMA, IL-1β, IL-6, and smaller area of sirius red staining(P<0.05, P<0.01). Pre-electroacupuncture tends to lower blood pressure, improve cardiac function and reduce myocardial fibrosis in high-salt-induced hypertension rats, which may be associated with inhibiting inflammatory response.

Feasibility of Precision Medicine in Hypertension Management-Scope and Technological Aspects.

Personalized management of diseases by considering relevant patient features enables optimal treatment, instead of management according to an average patient. Precision management of hypertension is important, because both susceptibility to complications and response to treatment vary between individuals. While the use of genomic and proteomic personal features for widespread precision hypertension management is not practical, other features, such as age, ethnicity, and cardiovascular diseases, have been utilized in guidelines for hypertension management. In precision medicine, more blood-pressure-related clinical and physiological characteristics in the patient's profile can be utilized for the determination of the threshold of hypertension and optimal treatment. Several non-invasive and simple-to-use techniques for the measurement of hypertension-related physiological features are suggested for use in precision management of hypertension. In order to provide precise management of hypertension, accurate measurement of blood pressure is required, but the available non-invasive blood pressure measurement techniques, auscultatory sphygmomanometry and oscillometry, have inherent significant inaccuracy-either functional or technological-limiting the precision of personalized management of hypertension. A novel photoplethysmography-based technique for the measurement of systolic blood pressure that was recently found to be more accurate than the two available techniques can be utilized for more precise and personalized hypertension management.

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.

Cuffless Blood Pressure Measurement Using Linear and Nonlinear Optimized Feature Selection.

The cuffless blood pressure (BP) measurement allows for frequent measurement without discomfort to the patient compared to the cuff inflation measurement. With the availability of a large dataset containing physiological waveforms, now it is possible to use them through different learning algorithms to produce a relationship with changes in BP. In this paper, a novel cuffless noninvasive blood pressure measurement technique has been proposed using optimized features from electrocardiogram and photoplethysmography based on multivariate symmetric uncertainty (MSU). The technique is an improvement over other contemporary methods due to the inclusion of feature optimization depending on both linear and nonlinear relationships with the change of blood pressure. MSU has been used as a selection criterion with algorithms such as the fast correlation and ReliefF algorithms followed by the penalty-based regression technique to make sure the features have maximum relevance as well as minimum redundancy. The result from the technique was compared with the performance of similar techniques using the MIMIC-II dataset. After training and testing, the root mean square error (RMSE) comes as 5.28 mmHg for systolic BP and 5.98 mmHg for diastolic BP. In addition, in terms of mean absolute error, the result improved to 4.27 mmHg for SBP and 5.01 for DBP compared to recent cuffless BP measurement techniques which have used substantially large datasets and feature optimization. According to the British Hypertension Society Standard (BHS), our proposed technique achieved at least grade B in all cumulative criteria for cuffless BP measurement.

Surrogate based continuous noninvasive blood pressure measurement.

Arterial blood pressure is one of the most often measured vital parameters in clinical practice. State-of-the-art noninvasive ABP measurement technologies have noticeable limitations and are mainly based on uncomfortable techniques of complete or partial arterial occlusion by cuffs. Most commonplace devices provide only intermittent measurements, and continuous systems are bulky and difficult to apply correctly for nonprofessionals. Continuous cuffless ABP measurements are still an unmet clinical need and a topic of ongoing research, with only few commercially available devices. This paper discusses surrogate-based noninvasive blood pressure measurement techniques. It covers measurement methods of continuously and noninvasively inferring BP from surrogate signals without applying external pressures, except for reference or initialization purposes. The BP is estimated by processing signal features, so called surrogates, which are modulated by variations of BP. Discussed techniques include well-known approaches such as pulse transit time and pulse arrival time techniques, pulse wave analysis or combinations thereof. Despite a long research history, these methods have not found widespread use in clinical and ambulatory practice, in part due to technical limitations and the lack of a standardized regulatory framework. This work summarizes findings from an invited workshop of experts in the fields covering clinical expertise, engineering aspects, commercialization and standardization issues. The goal is to provide an application driven outlook, starting with clinical needs, and extending to technical actuality. It provides an outline of recommended research directions and includes a detailed overview of clinical use case scenarios for these technologies, opportunities, and limitations.

Cardioprotective Effect of Ulmus wallichiana Planchon in β-Adrenergic Agonist Induced Cardiac Hypertrophy.

Ulmus wallichiana Planchon (Family: Ulmaceae), a traditional medicinal plant, was used in fracture healing in the folk tradition of Uttarakhand, Himalaya, India. The present study investigated the cardioprotective effect of ethanolic extract (EE) and butanolic fraction (BF) of U. wallichiana in isoprenaline (ISO) induced cardiac hypertrophy in Wistar rats. Cardiac hypertrophy was induced by ISO (5 mg/kg/day, subcutaneously) in rats. Treatment was performed by oral administration of EE and BF of U. wallichiana (500 and 50 mg/kg/day). The blood pressure (BP) and heart rate (HR) were measured by non-invasive blood pressure measurement technique. Plasma renin, Ang II, NO, and cGMP level were estimated using an ELISA kit. Angiotensin converting enzyme activity was estimated. BP and HR were significantly increased in ISO group (130.33 ± 1.67 mmHg vs. 111.78 ± 1.62 mmHg, p < 0.001 and 450.51 ± 4.90 beats/min vs. 347.82 ± 6.91 beats/min, respectively, p < 0.001). The BP and HR were significantly reduced (EE: 117.53 ± 2.27 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001, BF: 119.74 ± 3.32 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001); HR: (EE: 390.22 ± 8.24 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001, BF: 345.38 ± 6.79 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001) after the treatment of EE and BF of U. wallichiana, respectively. Plasma renin, Ang II, ACE activity was decreased and NO, cGMP level were increased. The EE and BF of U. wallichiana down regulated the expression of ANP, BNP, TNF-α, IL-6, MMP9, β1-AR, TGFβ1 and up regulated NOS3, ACE2 and Mas expression level, respectively. Thus, this study demonstrated that U. wallichiana has cardioprotective effect against ISO induced cardiac hypertrophy.

Sensitivity of two noninvasive blood pressure measurement techniques compared to telemetry in cynomolgus monkeys and beagle dogs

Introduction Animals are commonly used in toxicological research for the evaluation of drug effects on the cardiovascular system. Accurate and reproducible determination of blood pressure (BP) in conscious, manually restrained monkeys and dogs is a challenge with current non-invasive cuff techniques. The High Definition Oscillometry (HDO) technique enables real time measurements with immediate visual feedback via PC screen on data validity. HDO measurements are considerably faster with a duration of approximately 8 to 15 s than conventional cuff methods that can take several minutes. Methods HDO Memo Diagnostic Model Science and Cardell BP Monitor Model 9401 measurements were compared for accuracy and reliability with simultaneously recorded direct blood pressure data captured via radiotelemetry. Six monkeys and six dogs implanted with DSI PCT telemetry transmitters were used; BP data were collected by all methods under manual constraint and compared. Measurements were performed with HDO and Cardell in the presence of a BP lowering drug (hexamethonium bromide). Systolic, diastolic, mean arterial pressure, and pulse rate were determined before, during and following up to 10 mg/kg hexamethonium administration via intravenous slow bolus injection. Results Drug induced hemodynamic changes could be detected in monkeys and dogs with the HDO method but only in dogs with the Cardell method. Correlation coefficients were generally higher for HDO versus Telemetry than Cardell versus Telemetry comparisons, indicating that this novel, non-invasive technique produces reliable blood pressure data and is able to detect drug-induced hemodynamic changes. Discussion HDO provides an alternative approach for invasive telemetry surgeries to obtain reliable hemodynamic data in animal models for cardiovascular research when invasive techniques are not warranted.

Comparison of Invasive and Non-invasive Measurement of Spontaneous Baroreflex during Anesthesia

Background: Many works have shown that beat-to-beat variations in systolic arterial pressure (SAP) could be used for the assessment of cardiac baroreflex function. The purpose of this study was to evaluate whether Finapres, a non-invasive device to measure systolic arterial pressure, could serve as an acceptable alternative to intra-arterial catheterization for assessing the spontaneous baroreflex during anesthesia. Methods: Thirty ASA class I patients scheduled for surgical hepatic and gastric tumor excisions were enrolled in this study. Spontaneous baroreflex sensitivity (SBR) during anesthesia was calculated by sequence analysis of beat-to-beat variations in systolic arterial pressure and R-R intervals. Data obtained from Finapres were compared with those from standard intra-arterial catheterization technique. Results: SBR values determined by non-invasive and invasive blood pressure measurement technique were precisely correlated (r = 0.96) and the mean difference was about 0.22 ms/mmHg (12.5%). Howevet; the individual data might differ by -0.52 to + 0.96 ms/mmHg (-35% to + 60%). Conclusions: Finapres may trace the changes of SBR during anesthesia and provides similar results as does invasive method but individual variation exists.