Noninvasive Blood Pressure Device Research Articles

Comparison of Thames Medical CAT+ Doppler and SunTech Vet 20 oscillometric devices for non-invasive blood pressure measurement in conscious cats.

A comparative assessment of systolic blood pressure (BP) measurement agreement and precision in two commonly used non-invasive BP devices was carried out in conscious cats. Systolic BP measurements were obtained from 50 conscious cats as part of their clinical investigations. All measurements were taken by the same operator and were performed according to the American College of Veterinary Internal Medicine (ACVIM) consensus guidelines. The same cuff location and cuff size were used for paired measurements. The order of device use was randomised, and an arousal score was assigned during each procedure. Precision was assessed using standard deviation and coefficient of variance comparisons. Agreement was assessed using graphical and statistical comparisons of derived 'delta mean' and 'mean of means' data. A total of 50 cats aged between 3 months and 15 years were enrolled (29 domestic shorthair, seven domestic longhair, three British Shorthair, two Ragdoll, two Sphynx, two Persian, one Siamese, one Burmese, one Russian Blue, one Maine Coon and one Oriental) with a body weight in the range of 1.2-6.2 kg. BP measurements were in the range of 95-179 mmHg. Oscillometric measurements were associated with lower arousal scores. The Doppler device demonstrated superior repeatability precision. Body weight, sex, cuff size, cuff location, arousal score and the order in which the devices were used had no significant effect on precision or agreement. Correlation between the two devices was 0.0837 and agreement was considered clinically acceptable (<10 mmHg) in 32/50 (64%) cats. Of the 18 cats with suboptimal agreement, the oscillometric mean BP was higher in 14 (78%) cats. Based on this study sample, suboptimal agreement between paired CAT+ Doppler and SunTech Vet20 oscillometric BP measurements in 36% of conscious cats suggests that these devices should not be used interchangeably. Compared with Doppler, oscillometric measurements were consistently higher, particularly at higher blood pressures. Further studies are required to assess which device has superior accuracy in conscious cats.

Abstract 16382: Inaccuracy of Non-Invasive Brachial Cuff-Measured Blood Pressure During Surgery

Introduction: Blood pressure (BP) is an essential vital sign to be monitored during surgery. BP is measured only by Non-Invasive brachial Cuff-measured Blood Pressure (NICBP) devices in 90% of surgeries in US. However, previous studies demonstrated possible inaccuracy of NICBP. The inaccuracy of BP during surgery is a significant public concern because it can result in missing therapeutic potentials and consequently increasing cardiovascular risks during and after surgery. However, there is no large study to evaluate the accuracy of NICBP measured during surgery. Method: It has been known that invasive intra-arterial blood pressure (IABP) measured by an arterial line catheter is an optimal reference for validation of NICBP accuracy given its highest level of accuracy. Our study collected 2,814,154 pairs of BP measurements between NICBP and IABP which were measured at the same time during surgery from 38,706 patients who received surgeries at University of California, Los Angeles from 2016 through 2023. Result: We evaluated the accuracy of NICBP compared to IABP using Confusion matrix analysis (Fig 1). We defined predicted BP classification when BP is classified by NICBP. We also defined actual BP classification when BP is classified by IABP. We categorized BP according to Mean Arterial Pressure (MAP; mmHg) into 5 groups; MAP&lt;65, 65≤MAP&lt;75, 75≤MAP&lt;95, 95≤MAP&lt;105, and 105≤MAP. True Positive rates of each classification ranged from 36.7% to 66.7% (Fig 1). It was surprising that 49.9% in actual MAP (aMAP)&lt;65, 56.9% in 65≤aMAP&lt;75, 33.9% in 75≤aMAP&lt;95, 63.4% in 95≤aMAP&lt;105, and 50.6% in 105≤ aMAP was misclassified into the incorrect BP classifications by NICBP. Conclusion: Our study demonstrated noticeable inaccuracy of BP by NICBP compared to IABP during surgery. Given high reliability solely on NICBP in measuring BP during the majority of surgery cases, the inaccuracy of NICBP may cause significant public health concerns due to unoptimized BP management during surgery.

KOROTKOFF SOUNDS DO NOT PROVIDE AN ACCURATE ESTIMATE OF SYSTOLIC AND DIASTOLIC PRESSURE IN SPHYGMOMANOMETRY AND CANNOT BE USED AS A CALIBRATION STANDARD FOR NIBP DEVICES

Objective: Noninvasive blood pressure (NIBP) devices are calibrated against validated auscultation sphygmomanometers using Korotkoff sounds. This study aimed to investigate the timing of Korotkoff sounds in relation to pulse appearance in the brachial artery and values of intra-arterial blood pressure. Design and method: Experiments were carried out on 15 participants, (14 males, 64.3 ±10.4 years; one female, 86 yo), undergoing coronary angiography. A conventional (oscillometric) BP cuff, with a microphone for Korotkoff sounds, was placed on the upper arm. Intra-arterial brachial artery pressure (IABP) was measured below the cuff with a fluid-filled catheter inserted via the radial artery and an external transducer. Finger photoplethysmography was used to measure brachial pulse wave velocity (PWV). Korotkoff sounds were processed electronically and custom algorithms identified the cuff pressure (CP) at which the first and last Korotkoff sounds were heard. PWV and max slope of the IABP pressure pulse were recorded to estimate arterial stiffness. Results: The brachial artery closed at a CP of 132.0±17.1 mmHg. Systolic (SBP), and diastolic (DBP) pressure were 147.6±14.3 and 72.7±10.1mmHg; mean pressure (MP, 100.1±10.4 mmHg) was similar to MP derived from the peak of the oscillogram (98.5±13.6 mmHg). Difference between IABP and CP recorded at first and last occurrence of Korotkoff sounds were, SBP: 18.9±8.3 (range 2-29) mmHg, DBP: 4.0±4.3 (range -1.6 -12.4) mmHg. Multiple linear regression showed that differences increase with arterial stiffness and can be compensated for using a prediction equation for calculation of true SBP (tSBP) using heart rate (HR) and Korotkoff derived systolic (SBPk) and diastolic (DBPk), at least over the limited age range for this study cohort. Conclusions: SBP and DBP derived from the onset and termination of Korotkoff sounds can underestimate IABP by up to 29 mmHg. Since Korotkoff sounds are the recommended method mandated by the universal standard for the validation of blood pressure measuring devices, these errors are propagated through to all NIBP measurement devices irrespective of whether they use auscultatory or oscillometric methods thus explaining the well known differences recorded between NIBP measurements and intra-arterial BP measurements.

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.

High spatial and temporal resolution cerebrovascular reactivity for humans and large mammals: A technological description of integrated fNIRS and niABP mapping system.

Introduction: The process of cerebral vessels maintaining cerebral blood flow (CBF) fairly constant over a wide range of arterial blood pressure is referred to as cerebral autoregulation (CA). Cerebrovascular reactivity is the mechanism behind this process, which maintains CBF through constriction and dilation of cerebral vessels. Traditionally CA has been assessed statistically, limited by large, immobile, and costly neuroimaging platforms. However, with recent technology advancement, dynamic autoregulation assessment is able to provide more detailed information on the evolution of CA over long periods of time with continuous assessment. Yet, to date, such continuous assessments have been hampered by low temporal and spatial resolution systems, that are typically reliant on invasive point estimations of pulsatile CBF or cerebral blood volume using commercially available technology. Methods: Using a combination of multi-channel functional near-infrared spectroscopy and non-invasive arterial blood pressure devices, we were able to create a system that visualizes CA metrics by converting them to heat maps drawn on a template of human brain. Results: The custom Python heat map module works in "offline" mode to visually portray the CA index per channel with the use of colourmap. The module was tested on two different mapping grids, 8 channel and 24 channel, using data from two separate recordings and the Python heat map module was able read the CA indices file and represent the data visually at a preselected rate of 10 s. Conclusion: The generation of the heat maps are entirely non-invasive, with high temporal and spatial resolution by leveraging the recent advances in NIRS technology along with niABP. The CA mapping system is in its initial stage and development plans are ready to transform it from "offline" to real-time heat map generation.

GJD Modulates Cardiac/Vascular Inflammation and Decreases Blood Pressure in Hypertensive Rats.

Gedan Jiangya decoction (GJD) (aqueous ethanol extract), a traditional Chinese medicine formula which contain six botanical drugs (Uncaria rhynchophylla (Miq.) Miq., Salvia miltiorrhiza Bunge, Pueraria lobata (Willd.) Ohwi, Eucommia ulmoides Oliv., Prunella vulgaris L., and Achyranthes bidentata Blume) was designed to treat hypertension; however, the underlying mechanism of action is unclear. This study aimed to determine the mechanisms of action of GJD in the treatment of hypertension in spontaneously hypertensive rats (SHR). Male SHRs were randomly divided into five groups: GJD doses were low (1.36 g/kg/d), medium (2.72 g/kg/d), and high (5.44 g/kg/d), captopril (13.5 mg/kg/d), and SHR groups, with Wistar-Kyoto rats (WKY) serving as the control. Every rat was gavaged once a day. The ALC-NIBP, a noninvasive blood pressure device, measured systolic (SBP) and diastolic (DBP) blood pressures. Six weeks following treatment, all rats were anesthetized. The blood samples were obtained from the abdominal aorta and then serum isolated to assess endothelin-1 and angiotensin II, interleukin-1beta, interleukin-6, and TNF-alpha. The left ventricular and thoracic aortas were taken for HE staining, immunohistochemistry, RT-qPCR, and western blot examination. Following GJD therapy, SBP and DBP were significantly lowered, as were serum levels of endothelin-1 and angiotensin II. The thickness of the left ventricular and thoracic aorta walls reduced, as did type I collagen, type III collagen, and alpha-SMA expression in the left ventricular and aortic tissues. The GJD treatment significantly reduced serum levels of the inflammatory markers interleukin-1beta, interleukin-6, and TNF-alpha. Furthermore, interleukin-1 beta, interleukin-6, TNF-alpha, TAK1, and NF-κB/p65 levels were significantly reduced in left ventricular and aortic tissues, whereas IkB-alpha levels were significantly elevated. GJD has a dose-dependent effect on all parameters. In conclusion, GJD has been shown to lower blood pressure, improve cardiovascular remodeling, and reduce inflammation via regulating NF-κB in SHRs.

Proposing a Method to Measure NIBP Parameters Using PPG Signal and Analyzing the Morphology of Oscillometric

The demand for monitoring non-invasive blood pressure (NIBP) parameters in health facilities for medical examination and treatment, specifically self-monitoring at home is significantly increasing. The measurement methods are based on many different techniques. However, the accuracy and stability of the measurement results from these techniques are still controversial. In this study, we proposed a novel method to measure the two most important parameters in NIBP measurement by combining two techniques: observing the Photoplethysmogram (PPG) signal to determine the Systolic Blood Pressure (SBP) and analyzing the changes of the morphology of oscillometric pulses to determine the Mean Arterial Pressure (MAP). The results were attained from 30 volunteers by using the proposed model and two commercial NIBP devices from iChoice and Omron for comparison. The measuring results of the proposed model have shown a good correlation and high stability of SBP, DBP (Diastolic Blood Pressure) and MAP measurements compared to the current techniques, expressed by the correlation of determination R2, the mean difference of proposed model to each commercial device, NIBPP – NIBPiC, NIBPP – NIBPO, and the mean (SD) between measurement results of volunteers.

Systolic blood pressure measurements are unreliable for the management of acute spontaneous intracerebral hemorrhage.

Whether systolic blood pressure (SBP) is reliable in acute spontaneous intracerebral (sICH) by assessing agreement between simultaneous BP measurements obtained from cuff non-invasive blood pressure (NIBP) and radial arterial invasive blood pressure (AIBP) devices. Among 766 prospectively screened sICH subjects, 303 (39.5%) had NIBP and AIBP measurements. During the first 24 h, 2157 simultaneous paired measurement readings were abstracted. Paired NIBP/AIBP measurements were included in a Bland-Altman technique with 95% agreement limits and coefficients from regression analysis derived from a bootstrap procedure. Variance for SBP was 66.1 mmHg, which was larger than the 44.3 mg Hg for diastolic blood pressure (DBP) or the 46.1 mmHg for mean arterial pressure (MAP). Pairwise comparison of mean biases showed a significant difference between SBP when compared to DBP (p < 0.0001) or MAP (p < 0.0001). The mean bias between DBP and MAP was not different (p = 0.68). Regression-based Bland Altman analysis found significant bias (slope -0.16, 95% CI -0.23, -0.09, p < 0.05) over the range of mean SBP. Bias over the range of mean DBP or MAP was not significant. We concluded that SBP is an unreliable blood pressure measurement in patients with sICH.

Oscillometric Waveform Evaluation for Blood Pressure Devices

Most of the noninvasive blood pressure (NIBP) device algorithms have been derived from the clinical trials at various hospitals and human races in developed countries. It is urgent to develop an algorithm for NIBP devices for Indian citizens. In this regard, we have developed a flexible pressure sensor to record the human body's oscillometric waveform (OMW). As we know, assessing human blood pressure (BP) by noninvasive techniques is virtually a revolutionary step in biomedical science and engineering. High blood pressure is one of the most critical risk factors for heart disease and death; therefore, continuous monitoring of BP is necessary. We have obtained the BP pulse waveform by the flexible capacitive pressure sensor and further estimated the systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean blood pressure (MBP) using international guidelines. In this work, the BP simulation was performed on 64 waveforms, combinations of SBP (80–180 mmHg) and DBP (60–170 mmHg) to compute the BP in different health conditions such as hypotension, normal, and hypertension. In addition, an oscillometric waveform was also obtained from the brachial artery of a healthy person and analyzed for its utility as an NIBP waveform recorder. The SBP, DBP, and MBP were calculated from the oscillometric waveform envelope (OMWE) using the maximum amplitude algorithm (MAA) technique. In-house developed capacitive pressure sensors give comparable results when tested against the NIBP simulator and the commercial BP monitor. The pulse rate is also computed using the same OMW. The mean and standard deviation of the error in SBP, DBP, and MBP are within the universal standards' validation protocol for BP devices. The results indicate that the flexible capacitive pressure sensor can measure the BP with acceptable error and replace the commercial BP monitor and recorder sensor. The developed sensors show potential for large-scale clinical trials for blood pressure and pulse rate measurements.

Noninvasive Blood Pressure Measurement Using the NICCI Monitor in Adolescents During Intraoperative Anesthetic Care.

BackgroundThe intermittent measurement of blood pressure (BP) remains the standard of care during anesthesia or procedural sedation. To improve the early identification of hemodynamic compromise, various noninvasive BP devices have been developed which provide a continuous BP reading. The current study evaluates the accuracy of a novel continuous BP device, the NICCI system, in adolescents weighing 40 - 80 kg.MethodsDuring intraoperative anesthetic care, BP readings (systolic, diastolic, and mean) were captured from the arterial cannula and the NICCI device every second.ResultsThe study cohort included 44 pediatric patients undergoing major orthopedic, cardiac, and neurosurgical procedures. A total of 383,126 pairs of systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) values from the arterial cannula and the NICCI device were analyzed. The absolute difference for SBP, DBP, and MAP values from the NICCI monitor and the arterial cannula were 10 ± 8, 9 ± 7, and 9 ± 7 mm Hg, respectively. The difference between the BP values from the NICCI and the arterial cannula was ≤ 10 mm Hg for 60% of the SBP readings, 67% of the DBP readings, and 56% of the MAP readings. Using Bland-Altman analysis, the bias was 2, 3, and 4 mm Hg for the SBP, DBP, and MAP.ConclusionsAlthough there were technical limitations related to patient size that affected its ability to meet the strict accuracy criteria set by the American National Standards Institute/Association for the Advancement of Medical Instrumentation standards for noninvasive BP measurement (ANSI/AAMI SP10), the NICCI system provided a continuous noninvasive beat-to-beat BP measurement which was clinically relevant during a significant portion of intraoperative care.

Identifying Cognitive Impairment in Elderly Using Coupling Functions Between Cerebral Oxyhemoglobin and Arterial Blood Pressure.

BackgroundThis study aimed to assess brain oxygenation status and cerebral autoregulation function in subjects with cognitive dysfunction.MethodsThe Montreal Cognitive Assessment (MoCA) was applied to divide the subjects into three groups: cognitive impairment (Group CI, 72.50 ± 10.93 y), mild cognitive impairment (Group MCI, 72.02 ± 9.90 y), and normal cognition (Group NC, 70.72 ± 7.66 y). Near-infrared spectroscopy technology and a non-invasive blood pressure device were used to simultaneously measure changes in cerebral tissue oxygenation signals in the bilateral prefrontal lobes (LPFC/RPFC) and arterial blood pressure (ABP) signals from subjects in the resting state (15 min). The coupling between ABP and cerebral oxyhemoglobin concentrations (Δ [O2Hb]) was calculated in very-low-frequency (VLF, 0.02–0.07 Hz) and low-frequency (LF, 0.07–0.2 Hz) bands based on the dynamical Bayesian inference approach. Pearson correlation analyses were used to study the relationships between MoCA scores, tissue oxygenation index, and strength of coupling function.ResultsIn the interval VLF, Group CI (p = 0.001) and Group MCI (p = 0.013) exhibited significantly higher coupling strength from ABP to Δ [O2Hb] in the LPFC than Group NC. In the interval LF, coupling strength from ABP to Δ [O2Hb] in the LPFC was significantly higher in Group CI than in Group NC (p = 0.001). Pearson correlation results showed that MoCA scores had a significant positive correlation with the tissue oxygenation index and a significant negative correlation with the coupling strength from ABP to Δ [O2Hb].ConclusionThe significantly increased coupling strength may be evidence of impaired cerebral autoregulation function in subjects with cognitive dysfunction. The Pearson correlation results suggest that indicators of brain oxygenation status and cerebral autoregulation function can reflect cognitive function. This study provides insights into the mechanisms underlying the pathophysiology of cognitive impairment and provides objective indicators for screening cognitive impairment in the elderly population.

An Evaluation of the NICCI Monitor in Providing Continuous, Noninvasive Blood Pressure Readings in Children During Intraoperative Anesthetic Care

BackgroundIn specific clinical scenarios or with patient comorbid conditions, continuous blood pressure (BP) monitoring may be required as it can be expected to provide superior physiologic monitoring to intermittent techniques. However, continuous BP monitoring requires an arterial cannula (AC) placement, which may be time-consuming, technically challenging, or associated with adverse events. Various noninvasive BP devices have been developed which provide a continuous BP reading. The current study evaluates the accuracy of a novel continuous BP device, the NICCI monitor (NM), in pediatric patients weighing 10 - 40 kg.MethodsThe study cohort included pediatric patients weighing between 10 and 40 kg, scheduled for surgery for which placement of an AC was planned. Systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressure readings were captured from the AC and the NM every second during anesthetic care.ResultsThe study cohort included 24 pediatric patients undergoing major orthopedic, cardiac, and neurosurgical procedures. A total of 146,562 pairs of SBP, DBP, and MAP values from the AC and NC were analyzed. The absolute difference for the NM and the AC’s SBP, DBP, and MAP values were 11 ± 9, 10 ± 7, and 10 ± 7 mm Hg, respectively. The difference between the BP values from the NM and the AC was ≤ 10 mm Hg for 57% of the SBP readings, 60% of the DBP readings, and 56% of the MAP readings. The bias was 4, 4, and 6 mm Hg for the SBP, DBP, and MAP, respectively.ConclusionsAlthough there were some technical limitations given patient size, potentially resulting in variation in accuracy, the NM provided a continuous noninvasive BP measurement within clinically useful limits during a significant portion of anesthetic care compared to values obtained from an AC. Ongoing modification of the technology to improve its application in pediatric patients will likely increase its accuracy.

Inflationary noninvasive blood pressure monitoring reduces lower-limb pain during measurement

Objective: This study aimed to investigate whether inflationary noninvasive blood-pressure measurement reduces pain during blood-pressure monitoring with the lower limbs compared to the conventional noninvasive measurement method.Methods: Healthy volunteers aged ≥ 18 years were recruited for the study. After seating the participants, a manchette was fitted onto each limb (upper limbs: YP-713T YAWARA CUFF2 13 cm; lower limbs: YP-715T YAWARA CUFF2 for thigh 19 cm, Nihon Kohden Tokyo, Japan). The inflationary and conventional noninvasive blood-pressure measurement devices (PVM-9901 and PVM-9901, Nihon Kohden, Tokyo, Japan) were connected, and the blood pressure was measured simultaneously at two points in the upper and lower limbs. After the measurement, the participants answered a questionnaire regarding the lower-limb pain, and the intensity of pain was evaluated using the visual analog scale.Results: The study included 111 healthy volunteers. The visual analog scale scores of the upper and lower limbs were significantly lower with the inflationary noninvasive blood pressure measurement device than with the conventional noninvasive blood pressure device (upper limbs: 25.6 ± 23.2 vs. 38.8 ± 27.5, p &lt; .001 and lower limbs: 42.2 ± 25.1 vs. 54.2 ± 26.1, p &lt; .01, respectively).Conclusions: We examined the effect of pain reduction on the lower limbs with inflationary noninvasive blood-pressure measurements in healthy volunteers. We conclude that inflationary noninvasive blood pressure measurement may reduce pain in the lower limbs during blood-pressure monitoring compared to a conventional noninvasive blood pressure measurement.

Blood pressure measurement in the elderly with atrial fibrillation: an observational study comparing different noninvasive sphygmomanometers.

Atrial fibrillation (AF) has affected millions of adults in the world. It is important to monitor and manage blood pressure (BP) in AF patients. The accuracy of BP monitoring in AF patients with noninvasive methods remains questionable, however. To compare the accuracy of different noninvasive BP devices (oscillographic sphygmomanometer and pulse wave device) for BP measurement in elderly patients with AF, with a mercury sphygmomanometer as a reference. This study was an observational study. Patients with AF from the inpatient department of cardiology were included from 1 January to 31 December 2020. BP measurements were performed by two trained nurses using a tee junction connection on the cuff to connect three sphygmomanometers. The Bland-Altman plot analysis was conducted to compare the agreement of BP measurements. We also compared the agreement of BP measurements through metrics such as accuracy, bias, and precision. A total of 202 patients (54.5% female) were included. The Bland-Altman plot analysis showed that the lower and upper limits of agreement (LoAs) of pulse wave/reference were similar to the predefined acceptable clinical limits (10/5 mmHg). The bias and precision in both systolic and diastolic BP were significantly less in pulse wave/reference (a bias of 1.8 and 0.77 mmHg and a precision of 5.20 and 4.66 mmHg, respectively), with corresponding higher accuracy readings (98.51% for P10 in systolic BP and 85.64% for P5 in diastolic BP). A novel noninvasive sphygmomanometer - pulse wave device has a good concordance with a mercury sphygmomanometer in BP monitoring, and may be applicable to perform BP measurements in the elderly with AF.

Evaluation of the tongue for oscillometric measurement of arterial pressure in anesthetized Beagle dogs

ObjectiveTo evaluate the agreement between oscillometric blood pressure (OBP) measured from the tongue and invasive blood pressure (IBP), and to compare OBPs measured from the tongue with OBPs measured from the pelvic limb and tail. Study designProspective experimental study. AnimalsA total of eight adult Beagle dogs weighing 11.1 ± 1.2 kg. MethodsAnimals were premedicated with intravenous (IV) acepromazine (0.005 mg kg–1). Anesthesia was induced with alfaxalone (3 mg kg–1) IV and maintained with isoflurane. The dorsal pedal artery was catheterized for IBP measurements. Systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressure were simultaneously measured from the tongue, pelvic limb and tail. Based on invasive SAP, hypertension (>140 mmHg), normotension (90–140 mmHg) and hypotension (<90 mmHg) were induced by controlling end-tidal isoflurane concentrations and/or dobutamine/dopamine administration. Agreement between paired IBP and OBP measurements was analyzed with reference standards for noninvasive blood pressure devices used in small animals and humans. ResultsRegardless of cuff placement, the mean bias ± standard deviation between IBP and OBP met veterinary (≤10 ± 15 mmHg) and human (<5 ± 8 mmHg) standards for MAP and DAP. SAP measurements provided by the OBP device showed unacceptable agreement with IBP, and the bias between methods increased at higher blood pressures, regardless of cuff site. During hypotension, tongue OBP showed the largest percentage of absolute difference <10 mmHg in relation to IBP for SAP (90%), MAP (97%), and DAP (93%), compared with pelvic limb (60%, 97% and 82%, respectively) and tail OBP (54%, 92% and 77%, respectively). Conclusions and clinical relevanceThe tongue is a clinically useful site for measuring OBP in anesthetized Beagle dogs, providing reliable estimates of MAP and DAP. The tongue could replace other cuff placement sites and may be a relatively suitable site for assessing hypotension.

Antihypertensive Activity of Combination of Anredera cordifolia (Ten.) V. Steenis and Sonchus arvensis L. Leaves on Epinephrine Induced Male Wistar Rat.

In Indonesia, hypertension is a condition that can lead to death through stroke and TB. Herbs have traditionally been used in Indonesia as an alternative medicine for lowering blood pressure. The leaves of Anredera cordifolia and Sonchus arvensis have been investigated for their antihypertensive potential. Based on the number of treatments, rats were randomized into groups. Each group consists of five rats. The test animals were grouping as follows: the positive control group (hypertension induction without treatment), A. cordifolia 50 mg/kg b.w. group, A. cordifolia 100 mg/kg b.w., S. arvensis 50 mg/kg b.w, S. arvensis 100 mg/kg b.w., A. cordifolia 25 mg/kg b.w + S. arvensis 25 mg/kg b.w, A. cordifolia 50 mg/kg b.w + S. arvensis 50 mg/kg b.w, and atenolol 4.5 mg/kg b.w. The rats were given 0.25 mg/kg b.w. of epinephrine intraperitoneally. The initial, after induction, and final blood pressure of the animals were measured using the CODA® noninvasive blood pressure device. All animal test groups at T60 showed a significant difference in systolic and diastolic blood pressures to initial blood pressure (T0), P < 0.05. The combination of A. cordifolia 50 mg/kg b.w and S. arvensis 50 mg/kg b.w showed the highest percent inhibition of systolic and diastolic blood pressure. The combination of A. cordifolia and S. arvensis 50–50 mg/kg b.w showed the best effect of lowering systolic and diastolic blood pressure on the pathway of inhibiting adrenergic receptors.

Influence of noninvasive central blood pressure devices for afterload monitoring with aortic velocity-pressure Loop in anesthetized patients.

Global afterload angle (GALA) is a parameter derived from velocity-pressure loop (VP Loop), for continuous assessment of cardiac afterload in the operating room. It has been validated with invasive measure of central pressure. The aim of this study was to evaluate the feasibility of noninvasive VP Loop obtained with central pressure measured with two different noninvasive tonometers. A prospective, observational, monocentric study was conducted in 51 patients under general anesthesia. Invasive central pressure (cPINV) was measured with a fulfilled intravascular catheter, and noninvasive central pressure signals were obtained with two applanation tonometry devices: radial artery tonometry (cPSHYG: Sphygmocor tonometer) and carotid tonometry (cPCOMP: Complior tonometer). Three VP Loops were built: VP LoopINV, VP LoopSPHYG and VP LoopCOMP. Patients were separated according to cardiovascular risk factors. In the 51 patients under general anesthesia, cPSHYG was adequately obtained in 48 patients (89%) but, compared to cPINV, SBP was underestimated (-4 ± 6 mmHg, P < 0.0001), augmentation index (AIXSPHYG) and a GALASPHYG were overestimated (+13 ± 19%, P = 0.0077 and +4 ± 8°, P = 0.0024, respectively) with large limit of agreement (LOA) (-21 to 47% and -13 to 21° for AIXSPHYG and GALASPHYG, respectively). With the Complior, the failure rate of measurement for cPCOMP was 41%. SBP was similar (3 ± 17 mmHg, P = 0.32), AIXCOMP was underestimated (-11 ± 19%, P = 0.0046) and GALACOMP was similar but with large LOA (-50 to 26% and -20 to 18° for AIXCOMP and GALACOMP, respectively). In anesthetized patient, the reliability of noninvasive central pressure monitoring by tonometry seems too limited to monitor cardiac afterload with VP Loop.

The application of a neural network to predict hypotension and vasopressor requirements non-invasively in obstetric patients having spinal anesthesia for elective cesarean section (C/S)

BackgroundNeural networks are increasingly used to assess physiological processes or pathologies, as well as to predict the increased likelihood of an impending medical crisis, such as hypotension.MethodWe compared the capabilities of a single hidden layer neural network of 12 nodes to those of a discrete-feature discrimination approach with the goal being to predict the likelihood of a given patient developing significant hypotension under spinal anesthesia when undergoing a Cesarean section (C/S). Physiological input information was derived from a non-invasive blood pressure device (Caretaker [CT]) that utilizes a finger cuff to measure blood pressure and other hemodynamic parameters via pulse contour analysis. Receiver-operator-curve/area-under-curve analyses were used to compare performance.ResultsThe results presented here suggest that a neural network approach (Area Under Curve [AUC] = 0.89 [p < 0.001]), at least at the implementation level of a clinically relevant prediction algorithm, may be superior to a discrete feature quantification approach (AUC = 0.87 [p < 0.001]), providing implicit access to a plurality of features and combinations thereof. In addition, the expansion of the approach to include the submission of other physiological data signals, such as heart rate variability, to the network can be readily envisioned.ConclusionThis pilot study has demonstrated that increased coherence in Arterial Stiffness (AS) variability obtained from the pulse wave analysis of a continuous non-invasive blood pressure device appears to be an effective predictor of hypotension after spinal anesthesia in the obstetrics population undergoing C/S.This allowed us to predict specific dosing thresholds of phenylephrine required to maintain systolic blood pressure above 90 mmHg.

Evaluating the impact of motion artifact on noninvasive blood pressure devices.

Most automated sphygmomanometers use oscillometric algorithms. Motion, either patient-based or environmental, will affect the ability of a device to record an accurate blood pressure (BP). Members of the Association for the Advancement of Medical Instrumentation (AAMI) Sphygmomanometer Committee have been studying this problem for more than a decade. The AAMI TIR44 was the first publication to address the challenges of motion tolerance. The concepts described in TIR44 have led to the development of a draft of ISO 81060-4, a new standard for testing devices for which the manufacturer wishes to claim motion tolerance. The current ISO 81060-2 addresses both stress testing and 24-hour ambulatory BP monitoring. Recent publications have reported on testing of devices in response to voluntary and involuntary patient motion. The ISO 81060-4 will address testing in the presence of patient transport by ground, fixed-wing, and rotary (helicopter) ambulances. The protocol will utilize noise profiles recorded under those three conditions. The profiles will be digitally stored on a library with free access. The proposed testing will be performed using patient simulators introducing the noise library files into known BP oscillometric envelopes. The specifications of the data capture and playback devices are specified, as is the evaluation statistical testing. The authors expect that the final draft will be published in 2020.

Validation of the oscillometric blood pressure monitor Vet20 SunTech in anesthetized healthy cats

ObjectiveTo evaluate a veterinary-specific oscillometric noninvasive blood pressure (NIBP) system according to the guidelines of the American College of Veterinary Internal Medicine (ACVIM) Consensus Statement. Study designProspective clinical study. AnimalsA total of 33 client-owned cats (20 females and 13 males). MethodsCats were premedicated with methadone (0.3 mg kg−1) and alfaxalone (2 mg kg−1) intramuscularly. After 15 minutes anesthesia was induced with isoflurane (3%) in 100% oxygen by facemask while breathing spontaneously. A 22 gauge catheter was placed in the median caudal artery and systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures were measured. NIBP measurements were collected by placing the cuff (40% of limb circumference) on the right or left antebrachium. The agreement between the two methods was evaluated with the Bland–Altman methods, and the oscillometric NIBP device was evaluated using the ACVIM guidelines for validation of devices. ResultsData from 30 of the 33 cats were analyzed. Five paired measurements were taken from each cat, totaling 150 paired measurements. Mean bias (limits of agreements) for SAP, DAP and MAP were 2.7 (−22.7 to 28.1), 0.9 (−22.3 to 24.2) and 1.3 (−20.4 to 23.0). The oscillometric NIBP passed all validation criteria, except correlation which was <0.9 for SAP, DAP and MAP. Conclusions and clinical relevanceThe Vet20 did not meet all validation criteria by the ACVIM. However, all criteria except correlation were met.