Non-invasive Blood Pressure Measurement Research Articles

On the assessment of the ability of measurements, nowcasts, and forecasts to track changes.

Measurements, nowcasts, or forecasts ideally should correctly reflect changes in the values of interest. In this article, we focus on how to assess the ability of measurements, nowcasts, or forecasts to correctly predict the direction of changes in values - which we refer to as the ability to track changes (ATC). We review and develop visual techniques and quantitative measures to assess ATC. Extensions for noisy data and estimation uncertainty are implemented using bootstrap confidence intervals and exclusion areas. We exemplarily illustrate the proposed methods to assess the ability to track changes for nowcasting during the COVID-19 pandemic, patient admissions to an emergency department, and non-invasive blood pressure measurements. The proposed methods effectively evaluate ATC across different applications. The developed ATC assessment methods offer a comprehensive toolkit for evaluating the ATC of measurements, nowcasts, and forecasts. These techniques provide valuable insights into model performance, complementing traditional accuracy measures and enabling more informed decision-making in various fields, including public health, healthcare management, and medical diagnostics.

Abstract 4115642: Resonance Sonomanometry in an Early Prototype Device Effectively Measures Continuous, Noninvasive Blood Pressure

Background: Nearly half of American adults have hypertension; however, reliable, continuous, noninvasive blood pressure (BP) measurement (cNIBP) for inpatient and outpatient use is not currently available. This study evaluated a new method for cNIBP measurement called resonance sonomanometry (RSM). RSM derives blood pressure using first-principles physics, is applicable to any artery, and requires no calibration, blood vessel deformation, or dependence on demographic inputs. Methods: A prospective, observational feasibility study was undertaken to compare carotid artery BP measurements with a prototype ultrasound-based cNIBP device incorporating RSM, to arterial catheter BP measurements in the radial arteries of 60 test subjects. Catheter measurements were obtained from a distal peripheral artery (radial), oscillometric cuff from the brachial artery, and RSM was obtained from a central artery (carotid). This study was the first-in-human study for the RSM method in comparison to arterial catheters. Results: RSM-induced arterial resonance was observed in all tested subjects. For each of the subjects, the arterial resonant frequency increased with increasing BP during systole, and decreased with diastole (consistent with the cardiac cycle), as predicted by the physical model. RSM-derived BP traces were qualitatively similar to catheter data, exhibiting features such as the dicrotic notch. The RSM method yielded similar diastolic BP (DBP), but lower systolic BP (SBP) compared to the arterial catheter, likely due to expected peripheral pulse amplification. RSM DBP was not significantly different from the catheter (+1.5mmHg, p = 0.187), while BP cuff DBP was significantly different from the catheter (−4.3mmHg, p=0.002). There were significant differences in the catheter to RSM SBP (34.1 mmHg, p < 0.01), consistent with the aforementioned expectations from a central-versus-peripheral continuous pressure measurement. Conclusions: RSM is a novel BP measurement technique that could enable cNIBP measurements with accuracy required in hospitals. While the data are promising, significant future work remains. The study was meant to test the RSM method, not the device or form factor. Consequently, the form factor will need to be improved prior to clinical use. The prototype was designed for manual operation; thus, future work will also be needed to enhance the ability of the device to autonomously locate and track the artery for ease of use.

Cuff-less wearable biosensor in continuous noninvasive human radial artery pulse waveform and blood pressure measurement using self-mixing interferometry

In this paper, we propose a compact, wearable biosensor for the noninvasive measurement of human radial artery pulse waveform curve (PWC) and blood pressure (BP). In this system, self-mixing interferometry (SMI) technology is employed to measure the weak arterial vascular deformation, enabling accurate PWC retrieval. Based on the reconstructed PWC features, BP values are precisely estimated by means of deep learning method. Here continuous wavelet transform (CWT), enabling visualization of the relationship between the SMI signal temporal frequency components and the PWC characteristics, is highlighted for PWC flipping points seeking and convolutional neural network (CNN) input parameter acquisition. For the first time, a novel deep learning network preprocessing method is proposed that allows direct feature extraction from the CWT scalogram of SMI signal without the complicated PWC reconstruction algorithm. The robustness and accuracy of our device are validated by a series of clinical measurements, mean absolute error (MAE) and standard deviation (STD) values are calculated and compared with the existing models. We approach minimal BP estimation results (MAE ± STD) of 1.41 ± 1.89 mmHg for systolic blood pressure (SBP) and 1.78 ± 2.01 mmHg for diastolic blood pressure (DBP), respectively. The luxuriant novelties and remarkable performance clearly demonstrate our wearable sensor’s great potential in BP monitoring, and other clinical applications.

Valve unit instead of intensive care unit admission after transcatheter edge-to-edge tricuspid valve repair

Abstract Background Standardization of periprocedural pathways reduces the length of hospital stay and thus healthcare costs and increases patient safety. Post-procedure admission to the intensive care unit (ICU) after transcatheter edge-to-edge tricuspid valve repair (T-TEER) has been the standard of care. Due to the COVID-19 pandemic related decline in high-care hospital beds, our center established primary admission to a dedicated general cardiologic care ward, the valve unit (VU). Aim To assess benefits and risks of admission to the VU instead of ICU after T-TEER. Methods This retrospective observational study included 270 consecutive patients who underwent T-TEER between March 2017 and June 2023 at our university hospital. Patients were admitted to the ICU post-procedure up to April 9th 2020 as standard (ICU-group, n = 53). Subsequent patients were planned for admission to a dedicated VU (VU-group, n = 217). We compared the groups and assessed length of hospital stay and in-hospital complications. In the VU-group, we examined unplanned transfer to the ICU (cross-over) and its predictors. Results Monitoring at the VU included continuous telemetric ECG-recording, oxygen saturation assessment, periodical blood pressure measurements and 24-hours physician presence. In contrast to the ICU, only non-invasive blood pressure measurements, less frequent laboratory controls and less intense fluid monitoring took place. The postinterventional hospital stay of patients with planned VU admission was significantly shorter compared to patients with planned ICU admission (median 4 (interquartile range (IQR) 3 - 5) vs. 4 (IQR 4 - 5) days, p = 0.030). Remarkably, overall complication rates were low and cardiogenic shock, infections, bleeding, vascular complications, delirium and acute kidney injury requiring dialysis were similar in both groups. 37 patients that were planned for VU had to cross over to unplanned ICU admission (17.1 %). Patients that had crossed over to unplanned ICU treatment had significantly higher risk for acute kidney injury (20.0 vs. 10.0%, p = 0.039) and in-hospital mortality (5.6 vs. 0%, p = 0.045). Higher systolic pulmonary artery pressure (sPAP) (OR 1.048, 95 %-CI 1.015 – 1.082, p = 0.003), NYHA functional class >= III (OR 9.176, 95 % CI 1.141 – 74.396, p = 0.037), and pre-interventional tricuspid regurgitation (TR) grade V (OR 2.941, 95 % CI 1.089 – 7.970, p = 0.033) were found to independently predict cross-over to unplanned ICU treatment. Conclusion Postinterventional admission to the VU instead of ICU after T-TEER shortens postprocedural hospital stay. A small proportion of had an unplanned transfer to ICU, which was accompanied by slightly higher complication rates. This cross-over affects patients with more advanced disease indicated by high pulmonary pressures, NYHA class and TR grade. Thus, admission to a valve unit is favorable for most patients after T-TEER, but those with advanced disease should be monitored more closely.

Evaluation of myocardial work indexes in patients with cardiac sarcoidosis

Abstract Background Cardiac involvement is associated with worse prognosis and mortality in sarcoidosis. Diagnosis often requires expensive and less available tests. Purpose The aim of this study is to evaluate whether non-invasive measurement of myocardial work by transthoracic echocardiogram has incremental value in the diagnosis of cardiac involvement compared to left ventricular (LV) global longitudinal strain (GLS). Methods This is a cross-sectional, non-blinded, single-center pilot study. Patients of both genders > 18 years old, with confirmed diagnosis of cardiac sarcoidosis according to the Heart Rhythm Society criteria, and controls consisting of individuals diagnosed with systemic sarcoidosis without cardiac involvement, were included. Patients with obesity grade 2 or higher , moderate or severe primary heart valve disease, myocardial diseases of other etiologies, established coronary artery disease, and inadequate acoustic window were excluded. All patients underwent transthoracic echocardiography and non-invasive blood pressure measurement, followed by subsequent analysis involving the construction of a pression-strain curve. The following LV indexes were calculated: GLS, global work index, global constructive work, global wasted work, and global work efficiency. ROC curves were calculated for all variables using the EasyROC online tool (v 1.3.1), and these were later compared to GLS. Confidence intervals were established by the DeLong method, and curves were compared by the Bonferroni method. A two-tailed p value of 0.05 was considered significant. Results Twenty patients with cardiac involvement and twenty patients without cardiac involvement were evaluated. The results of the variables are presented in table 1. Conclusions With exception of wasted work, all other LV myocardial work variables showed statistical correlation with cardiac involvement in sarcoidosis patients. However, there was no incremental value of myocardial work indexes compared to the isolated use of GLS.

Incorporating intrathoracic pressure fluctuation can improve noninvasive prediction of left ventricular end-diastolic pressure

Abstract Introduction Heart failure (HF) is a leading cause of mortality and morbidity, with a prevalence above 10% in elderly population (1). Left ventricular end-diastolic pressure (LVEDP) is a known indicator for all types of HF. An invasive pressure catheter is the gold standard for measuring LVEDP (2). However, it involves an in-hospital procedure and is costly, which limits the accessibility. A noninvasive strategy would improve early diagnosis and reduce the burden on secondary care. Several noninvasive classifiers are able to detect elevated LVEDP (3-5), with some receiving FDA clearance (6). While beneficial for triaging patients, these classifiers cannot quantify the severity and track disease progression. Developing a noninvasive LVEDP regression model requires accounting for respiration dynamics. Even invasively, the dynamics make measuring LVEDP challenging. This study uses an error metric from ANSI/AAMI/ISO 81060-2:2019 (AAMI) (7) to evaluate the effect of respiration on noninvasive LVEDP regression results. Methods The dataset (147 patients, 21+ yrs old, mean 65 ± 10 yrs; 68% male) consisted of patients referred for nonemergent left heart catheterisation inclusive of direct assessment of LVEDP. Noninvasive data was collected by a modified brachial cuff with a single-lead electrocardiogram (ECG). Invasive data was acquired using a Millar pressure catheter. LVEDP was derived based on the time of the R-wave of the ECG (8). For each patient, 40 secs of noninvasive data with synchronised catheter signals were analysed to build an LVEDP regression model. Inputs were generated from the ECG and brachial pressure waves based on fiducials identified in both signals. Leave-one-subject-out cross-validation (LOSO CV) was used to train and test the algorithm. The impact of respirophasic variation on the model was analysed by comparing the prediction with the mean LVEDP and the range of the mean ± standard deviation (std) (i.e. AAMI error metric). Results The results, evaluated using Bland-Altman and correlation analysis, showed a decrease in the mean absolute error (MAE) from 3.6 mmHg to 1.4 mmHg, the std from 4.9 mmHg to 3.0 mmHg, and the correlation (r) from 0.57 to 0.77 when incorporating intrathoracic pressure swings (Fig.1 and Fig.2). A Levene test on the residuals of the two error determinations showed a significant difference (p-value < 0.01). Conclusion Irrespective of the error metric, the model performance meets the AAMI standard for blood pressure (BP) measurement. Moreover, when respiratory motion is included, agreement with invasive LVEDP improves considerably. From a clinical perspective, this emphasises the importance of targeting end-expiratory LVEDP. With respect to noninvasive BP measurement, it suggests that both brachial BP evaluation and LVEDP prediction should attempt to quantify fluctuations. While the challenge remains, these results indicate that noninvasive LVEDP prediction could be realised in the near future.Fig.1 Prediction vs mean LVEDP.Fig. 2 Prediction vs mean +/- std.

Non-invasive blood pressure measurement in conscious rabbits: A comparison of Doppler ultrasonic and oscillometric devices.

This study aimed to compare Doppler (the most commonly used technique for non-invasive indirect blood pressure [NIBP] measurement in rabbits) and oscillometric devices for NIBP measurements in conscious rabbits. Blood pressure (BP) measurements were obtained for49 conscious rabbits using the Doppler and oscillometric devices. Each measurement was repeated in triplicate. Three rabbits were excluded from the study because it was not possible to obtain BP measurements using the oscillometric device. The American College of Veterinary Internal Medicine (ACVIM) guidelines were followed to compare the results obtained with the two devices. A total of 164 systolic BP measurements were obtained with the Doppler device and 182 were obtained with the oscillometric technique. The mean of the three values obtained for each animal with each device was used for statistical analysis. The analysis demonstrated a poor level of agreement between the measurements obtained with the two devices. Oscillometric devices rely on built-in software algorithms to perform calculations and produce their measurements. However, the oscillometric devices currently available only have the software for dogs and cats installed. Therefore, these conclusions should be revised when a device with software specifically for rabbits is commercialised. This study indicates that oscillometric devices should not be used as a substitute for the Doppler technique when measuring BP in rabbits.

In silico data-based comparison of the accuracy and error source of various methods for noninvasively estimating central aortic blood pressure

Background and objectivesThe higher clinical significance of central aortic blood pressure (CABP) compared to peripheral blood pressures has been extensively demonstrated. Accordingly, many methods for noninvasively estimating CABP have been proposed. However, there still lacks a systematic comparison of existing methods, especially in terms of how they differ in the ability to tolerate individual differences or measurement errors. The present study was designed to address this gap. MethodsA large-scale ‘virtual subject’ dataset (n = 600) was created using a computational model of the cardiovascular system, and applied to examine several classical CABP estimation methods, including the direct method, generalized transfer function (GTF) method, n-point moving average (NPMA) method, second systolic pressure of periphery (SBP2) method, physical model-based wave analysis (MBWA) method, and suprasystolic cuff-based waveform reconstruction (SCWR) method. The errors of CABP estimation were analyzed and compared among methods with respect to the magnitude/distribution, correlations with physiological/hemodynamic factors, and sensitivities to noninvasive measurement errors. ResultsThe errors of CABP estimation exhibited evident inter-method differences in terms of the mean and standard deviation (SD). Relatively, the estimation errors of the methods adopting pre-trained algorithms (i.e., the GTF and SCWR methods) were overall smaller and less sensitive to variations in physiological/hemodynamic conditions and random errors in noninvasive measurement of brachial arterial blood pressure (used for calibrating peripheral pulse wave). The performances of all the methods worsened following the introduction of random errors to peripheral pulse wave (used for deriving CABP), as characterized by the enlarged SD and/or increased mean of the estimation errors. Notably, the GTF and SCWR methods did not exhibit a better capability of tolerating pulse wave errors in comparison with other methods. ConclusionsClassical noninvasive methods for estimating CABP were found to differ considerably in both the accuracy and error source, which provided theoretical evidence for understanding the specific advantages and disadvantages of each method. Knowledge about the method-specific error source and sensitivities of errors to different physiological/hemodynamic factors may contribute as theoretical references for interpreting clinical observations and exploring factors underlying large estimation errors, or provide guidance for optimizing existing methods or developing new methods.

Agreement of Doppler Ultrasound and Visual Sphygmomanometer Needle Oscillation with Invasive Blood Pressure in Anaesthetised Dogs.

Visual sphygmomanometer needle oscillation (SNO) can occur before audible return of pulsatile flow (ARPF) when measuring blood pressure by Doppler ultrasound. The aim was to assess the agreement of SNO and ARPF with invasive blood pressure (iABP) in a clinical population of anaesthetised dogs. A total of 35 dogs undergoing surgery in dorsal recumbency necessitating arterial cannulation were included. Paired measurements of iABP and SNO, and iABP and ARPF, were collected. The agreement of non-invasive blood pressure (NIBP) and iABP measurements was analysed with concordance correlation coefficients (CCCs) and Bland-Altman plots. The proportions of SNO and ARPF measurements between 10 and 20 mmHg of iABP were compared. Both SNO and ARPF demonstrated greater agreement with invasive systolic (iSAP) than invasive mean (iMAP) pressures, and SNO demonstrated greater agreement with iSAP than ARPF measurements. The mean differences (95% limits of agreement) for SNO and APRF were -9.7 mmHg (-51.3-31.9) and -13.1 mmHg (-62.2-35.9), respectively. The CCC (95% CI) for SNO was 0.5 (0.36-0.64) and ARPF was 0.4 (0.26-0.54). A significantly greater proportion of SNO measurements were within 20 mmHg of iSAP compared to ARPF. Both NIBP techniques performed more poorly than veterinary consensus recommendations for device validation. Caution should be used clinically when interpreting values obtained by Doppler ultrasound in anaesthetised dogs.

The Role of Downsizing of Large-Bore Percutaneous Femoral Access for Pelvic and Lower Limb Perfusion in Transfemoral Branched Endovascular Aortic Repair.

Background: Transfemoral access (TFA) is a valuable alternative to upper extremity access (UEA) for branched endovascular aortic repair (bEVAR). However, TFA requires large introducer sheaths, which can reduce blood flow to lower limbs and the pelvis. This study aimed to evaluate the efficacy of sheath downsizing to maintain lower limb perfusion during TFA-bEVAR. Methods: A single-center retrospective review was conducted including patients managed with TFA-performed bEVAR between December 2020 and May 2021. Intra-operative lower limb perfusion was assessed using non-invasive ankle blood pressure measurements and great toe pulse oximetry, with measurements being taken prior to puncture (baseline), one minute after 10F-sheath insertion, three minutes after the main body delivery system insertion, and three minutes after downsizing to a 14F sheath. Outcomes included the incidence of limb perfusion reduction (LPR), defined as a drop in the ankle-brachial index (ABI) < 0.5 or peripheral oxygen saturation (SpO2) < 90%. Results: Out of 47 patients, 24 met the inclusion criteria. LPR occurred in 4.2% of cases after 10F-sheath placement, and 87.5% after main body delivery system placement, and decreased to 12.6% after downsizing to a 14F sheath. No periprocedural major bleeding occurred. Two patients required revision for inadequate hemostasis post-operatively. SCI occurred in 16% of patients, all recovered by discharge. Pre-operative hypogastric artery occlusion was related to persistent LPR after downsizing (100% vs. 16%, p = 0.009). Conclusions: Downsizing the introducer sheath during bEVAR is feasible and safe to restore lower limb and pelvic perfusion. Further research is needed to clarify the access downsizing value during bEVAR.

Abstract P195: Vascular MAPK/ERK Activation in sFTL-1-Induced Preeclampsia In Vivo

Vascular endothelial growth factor (VEGF) inhibition is linked to the development of hypertension and proteinuria in preeclampsia. This occurs as anti-angiogenic factors from the placenta contribute to pregnancy-related hypertension disorder. Soluble VEGF receptor fms-like tyrosine kinase-1 (sFLT-1) is an anti-angiogenic factor that counteracts VEGF. Levels of sFLT-1 are three times higher in preeclamptic placentas compared to those from normotensive pregnancies, and plasma sFLT-1 levels increase with the severity of preeclampsia. Infusing sFLT-1 in rodents induces hypertension, proteinuria, and glomerular endotheliosis, resembling the human condition of preeclampsia. Currently, there is no effective pharmacological treatment of preeclampsia, and in severe cases, early delivery is often the only effective treatment. In this study, we aim to determine how sFLT-1 exposure affects the activation of the vascular MAPK/ERK pathway and the contractility of the aorta ex-vivo using wire myography, to assess if the MAPK/ERK pathway can be a therapeutic target in preeclampsia. To this end, we treated pregnant female C57BL/6 mice from embryonic day E7.5 to E18.5 with either sFLT-1 (3.7mg/kg/day) or vehicle (phosphate-buffered saline) delivered by osmotic minipumps (intraperitoneal) and carried out non-invasive tail-cuff blood pressure measurements. After sacrifice, we isolated descending thoracic aorta for isometric tension measurements in a wire myograph. Infusion of sFLT-1 resulted in marked systolic blood pressure (SBP) elevation (D increase of 14 mmHg, P=0.0003) and augmented aortic phosphorylated-ERK activation (2-fold increase, P=0.040) by western blot and displayed impaired acetylcholine-induced endothelial relaxation in thoracic aortic segments (P&lt;0.05), providing in vivo evidence of increased vascular p-ERK activation, accompanied by higher SBP and endothelial dysfunction in sFLT-1 - indued mouse model of preeclampsia. Future experiments are aimed to test the effect of pharmacological ERK inhibition in sFLT-1 infusion in vivo . We hypothesize that sFLT-1-induced rise in SBP and vascular p-ERK could be prevented in vivo by treatment with the pharmacological ERK inhibitor.

Hallazgos bioquímicos y ecográficos en caninos obesos

The aim of this study was to identify comorbidities in obese canines attending Centro de Veterinaria y Zootecnia CES, Medellín, Colombia. Thirty canines with a body condition of 7/9 to 9/9 were evaluated. Those with signs of systemic disease or endocrinopathy were excluded. An evaluation of body condition, abdominal ultrasound (with emphasis on pancreas, liver and adrenal glands), non-invasive blood pressure measurement and blood analysis of cholesterol, triglycerides, glucose and canine-specific pancreatic lipase (cPLI) were performed. The results showed that 19 individuals presented hypertriglyceridemia, and those with higher triglyceride values presented ultrasound findings of vacuolar liver disease (p&lt;0.01). Systolic blood pressure, cholesterol, glucose and cPLI were found within normal ranges and without differences between body condition ranges. The importance of including abdominal ultrasound in the diagnosis of obese patients is highlighted. It is concluded that hypertriglyceridemia associated with obesity leads to the accumulation of hepatic fatty infiltrates and vacuolar liver disease.

Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements

BackgroundBlood pressure monitoring is important in the pre-hospital management of critically ill patients. Non-invasive blood pressure (NIBP) measurements are commonly used but the accuracy of standard oscillometric cuff devices may be affected by extremes of physiology and adverse conditions (e.g. vibration) during transport. This study aimed to quantify the accuracy of NIBP measurements amongst patients requiring pre-hospital critical care.MethodsA retrospective cohort study was undertaken using data from patients treated by a pre-hospital critical team between 1st May 2020 and 30th April 2023 that had NIBP measured concurrently with invasive blood pressure (IBP) arterial manometry. An acceptable difference was determined a priori to be < 20mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP), and < 10mmHg for mean arterial pressure (MAP). The primary outcome was “pairwise agreement”, i.e. the proportion of paired observations that fell within this range of acceptability. Bland-Altman plots were constructed together with 95% limits of agreement to visualise differences between pairs of data. Associations with patient age, reason for critical care, transport status, haemodynamic shock, severe hypertension, and arterial catheter position were explored in univariate analyses and by fitting multivariable logistic regression models.ResultsThere were 2,359 paired measurements from 221 individual patients with a median age of 57. The most frequent reason for transport was cardiac arrest (79, 35.7%). Bland-Altman analyses suggested unacceptably wide limits of agreement with NIBP overestimating both SBP and MAP during hypotension and underestimating these values during hypertension. Haemodynamic shock (SBP < 90mmHg) was independently associated with reduced pairwise agreement for SBP (adjusted odds ratio [aOR] 0.52, 95% CI 0.35 to 0.77), DBP (aOR 0.65, 95% CI 0.42 to 0.99) and MAP (aOR 0.53, 95% CI 0.36 to 0.78) and severe hypertension (SBP > 160mmHg) with reduced pairwise agreement for SBP (aOR 0.17, 95% CI 0.11 to 0.27). There was no association between patient transport and agreement between the methods for SBP, DBP, or MAP.ConclusionsNon-invasive blood pressure measurements are often inaccurate in the pre-hospital critical care setting, particularly in patients with haemodynamic instability. Clinicians should be cautious when interpreting NIBP measurements and consider direct arterial pressure monitoring when circumstances allow.

Effects of acupuncture on endothelial active factors and related autonomic neurotransmitters in spontaneous hypertension rats

To observe the effects of acupuncture at "antihypertensive acupoint prescription" on endothelial active factors and related autonomic neurotransmitters in spontaneous hypertension rats, and explore the vascular regulation and central regulation mechanisms of acupuncture for anti-hypertension. Thirty SPF grade male spontaneous hypertension rats were randomly divided into a model group (15 rats) and an acupuncture group (15 rats). Besides, 15 Wistar Kyoto rats were collected as a blank control group (normal group). In the acupuncture group, acupuncture was delivered at the "antihypertensive acupoint prescription" (bilateral "Renying" [ST 9], "Quchi" [LI 11], "Zusanli" [ST 36], "Taichong" [LR 3] and "Neiguan" [PC 6]), with needles retained for 30 min, once daily. The duration of intervention was 28 days. Every week, using the the irritation scale, the sign of sympathetic irritation was evaluated dynamically. The arterial blood pressure of the rats tail was determined, using non-invasive blood pressure measurement system. ELISA was adopted to detect the levels of calcitonin gene-related peptide (CGRP), nitric oxide (NO), endothelin-1 (ET-1), neuropeptide Y (NPY) in the serum. DAB chromogenic in situ hybridization (CISH) was provided to detect the mRNA expression of endothelial nitric oxide synthase (eNOS) in the internal carotid artery and the arcuate nucleus (ARC), and that of CGRP in the paraventricular nucleus posterior (PVP) and the ventrolateral medulla (VLM). Liquid chromatography-mass spectrometry (LC-MS) was used to detect the levels of epinephrine (E) and norepinephrine (NE) in the paraventricular nucleus anterior (PVA). Compared with the normal group, the irritation scores, systolic blood pressure and diastolic blood pressure were increased at each time point in the model group (P<0.05). When compared with the model group, the irritation scores after the intervention for 3 and 4 weeks, and systolic and diastolic blood pressure after intervention for 2, 3 and 4 weeks were reduced in the acupuncture group (P<0.05). In comparison with the normal group, the serum CGRP and NO levels of the rats were decreased (P<0.05), and the serum ET-1 and NPY levels, as well as E and EN levels in PVA were increased (P<0.05) in the model group. The levels of serum CGRP and NO were elevated (P<0.05), and the serum ET-1 and NPY levels, as well as E and EN levels of PVA were reduced (P<0.05) in the acupuncture group when compared with those of the model group. In the model group, the media of internal carotid artery exhibited thickening and remodeling, while the neuron volume in ARC was small. In the acupuncture group, every layer of internal carotid artery was acceptably arranged, and the parvicellular neuron of ARC was moderate in volume. For the in situ hybridization of eNOS mRNA for the rats of each group, the smooth muscle cells were predominantly expressed in each layer of the internal carotid artery, whereas the expression of parvicellular neurons was dominated in ARC. In the model group, the large and small neurosecretory cells were distributed sparsely in the nerves of PVP; in the acupuncture group, the cells of these two species were distributed regularly; and there were few species of glial cell in the VLM of either the model group or the acupuncture group. In each group, for the in situ hybridization of CGRP mRNA, the small neurosecretory cells were expressed predominately in the PVP, while, the expression of glial cell nuclei and the cell cytoplasm was dominated in the VLM. Compared with the normal group, the mRNA expression of eNOS in the internal carotid artery and ARC and that of CGRP mRNA in the PVP and VLM was decreased in the model group (P<0.05). In the acupuncture group, when compared with the model group, the mRNA expression of eNOS in the internal carotid artery and ARC and that of CGRP in the PVP and VLM was increased in the acupuncture group (P<0.05). Acupuncture at "antihypertensive acupoint prescription" can upregulate the level of vascular relaxing factors, downregulate the level of contracting factors, enhance the response of relaxing factors in targeting blood vessels and regulating the center. The mechanism may be related to the modulation of the sympathetic-adrenergic autonomic neurotransmitters in the paraventricular nucleus in spontaneous hypertension rats.

Non-invasive blood pressure measurement from the finger using an optical system based on dynamic light scattering

Non-invasive blood pressure measurement from the finger using an optical system based on dynamic light scattering

Comparação da monitorização invasiva e não invasiva da pressão arterial em Cuniculus paca (Paca)

Cuniculus paca, a South American wild rodent with zootechnical potential, requires anesthesia for management procedures. However, limited information is available regarding safe monitoring of this animal under anesthesia. This study aimed to compare with gold standard invasive method and validate non-invasive blood pressure measurements using an oscillometric monitor in Cuniculus paca. Eight healthy adult females undergoing general anesthesia for follicular aspiration were included. Systolic, diastolic, and mean arterial pressures were measured simultaneous using, oscillometric non-invasive monitor with its cuff placed on the radial artery and an invasive catheter placed in the dorsal metatarsal artery. Measurements were compared using the t-test, correlated by Pearson test, and analyzed using the Bland-Altman concordance test. The results indicated that only systolic pressure measured by non-invasive oscillometric methos was similar to the pressure measurement by invasive method (P=0.6372, r=0.5969, bias 0.59±20.9 mmHg); while mean and diastolic pressures were underestimated by the non-invasive method. In conclusion, non-invasive oscillometric monitor provides a valid and reliable method for systolic blood pressure measurement in Cuniculus paca under general anesthesia.

A comparative study of ProRithm and standard monitoring techniques for non-invasive blood pressure measurement using photoplethysmography and electrocardiography signals through artificial intelligence/machine learning methods

Background: Multi-parameter monitoring devices are essential for providing real-time patient data, which is crucial for effective healthcare interventions. This clinical trial evaluated the accuracy of the ProRithm beat-to-beat cuffless device for arterial blood pressure monitoring, comparing it with a standard sphygmomanometer. Methods: This observational study included 30 subjects aged 18 and above. Systolic and diastolic blood pressure measurements from both the ProRithm device and the Philips Monitor were compared using statistical analysis. Results: The analysis revealed no statistically significant differences between the ProRithm device and the manual method. In comparison with manual measurements using a sphygmomanometer, the mean systolic blood pressure was 131.2 mmHg with ProRithm it was 129.3 mmHg. Similarly, with the manual method, while the mean diastolic blood pressure was 76.2 mmHg and with ProRithm it was 75.9 mmHg. Conclusions: This study indicates that portable, small-sized devices like ProRithm, which facilitate remote monitoring, are effective for real-time blood pressure assessment in clinical settings.

Comparison of invasive blood pressure monitoring vs. non-invasive blood pressure monitoring in critically ill children receiving vasoactive agents-a prospective observational study.

The primary aim of this study was to compare non-invasive blood pressure (NIBP) measurement using the automated oscillometric method with invasive blood pressure (IBP) measurement using peripheral arterial line insertion in critically ill children receiving vasoactive agents. Single-centre, prospective cohort study. Tertiary care 15 bedded Pediatric ICU in Urban Indian city. All critically ill children between the ages of 1 month to 16 years with shock on vasoactive medications and with IBP monitoring. Forty children with 1,072 paired BP measurements were incorporated in the final analysis. Among all normotensive children (Total number of paired measurements = 623) receiving vasoactive agents, Bland-Altman analysis revealed an acceptable agreement between Invasive mean blood pressure (MBP) and non-invasive MBP with a bias of -2.10 mmHg (SD 11.35). The 95% limits of agreement were from -24.34 to 20.14 mmHg. In children with hypotension (Total number of paired measurements = 449), Bland-Altman analysis showed disagreement between Invasive MBP and non-invasive MBP i.e., a bias of -8.44 mmHg (SD 9.62). The 95% limits of agreement were from -27.29 to 10.41 mmHg. A limited agreement exists between invasive blood pressure (IBP) and non-invasive blood pressure (NIBP) measurements in critically ill children requiring vasoactive agents. This discrepancy can lead to either an underestimation or an overestimation of blood pressure. While NIBP can serve as a screening tool for hemodynamically stable children, those who are hemodynamically unstable and necessitate the initiation of vasoactive agents should undergo IBP monitoring.

Validation of oscillometric ratio and maximum gradient methods for non-invasive blood pressure measurement with intra-arterial blood pressure measurements as reference.

Most non-invasive blood pressure (BP) measurements are carried out using instruments which implement either the Ratio or the Maximum Gradient oscillometric method, mostly during cuff deflation, but more rarely during cuff inflation. Yet, there is little published literature on the relative advantages and accuracy of these two methods. In this study of 40 lightly sedated individuals aged 64.1 ± 9.6 years, we evaluate and compare the performance of the oscillometric ratio (K) and gradient (Grad) methods for the non-invasive estimation of mean pressure, SBP and DBP with reference to invasive intra-arterial values. There was no significant difference between intra-arterial estimates of mean pressure made via Korotkoff sounds (MP-OWE) or the gradient method (MP-Grad). However, 17.7% of MP-OWE and 15% of MP-Grad were in error by more than 10 mmHg. SBP-K and SBP-Grad underestimated SBP by 14 and 18 mmHg, whilst accurately estimating DBP with mean errors of 0.4 ± 5.0 and 1.7 ± 6.1 mmHg, respectively. Relative to the reference standard SBP-K, SBP-Grad and DBP-Grad were estimated with a mean error of -4.5 ± 6.6 and 1.4 ± 5.6 mmHg, respectively, noting that using the full range of recommended ratios introduces errors of 12 and 7 mmHg in SBP and DBP, respectively. We also show that it is possible to find ratios which minimize the root mean square error (RMSE) and the mean error for any particular individual cohort. We developed linear models for estimating SBP and SBP-K from a range of demographic and non-invasive OWE variables with resulting mean errors of 0.15 ± 5.6 and 0.3 ± 5.7 mmHg, acceptable according to the Universal standard.

Atrial fibrillation ablation performed under general anesthesia is associated with significantly low arterial blood pressure and higher incidence of hypotensive events

Abstract Introduction Catheter ablation is a pivotal treatment for atrial fibrillation (AF). When performed under general anesthesia (GA), it may be associated to hypotensive events, with unclear prevalence and prognostic impact. Continuous non-invasive blood pressure (CNBP) measurement is a validated and reliable tool for intraprocedural beat-to-beat advanced hemodynamic monitoring. Purpose To assess and compare the hemodynamic impact of GA during AF ablation using a CNBP (ClearSight) system. Methods In an observational single large volume center study we prospectively enrolled all patients undergoing AF ablation at our institution with CNBP monitoring, as per local practice. Patients were assigned to deep sedation (DS) or general anesthesia (GA) group according to the chosen sedation regimen. The following parameters were compared between the two strategies: systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), cardiac output (CO), cardiac index (CI), stroke volume (SV), stroke volume index (SVI). Hypotension events (HE) (MAP &amp;lt; 65 mmHg) were counted and compared between groups. Results Two hundred patients were enrolled from September 2022 to August 2023. 170 patients underwent AF ablation under DS (76,7% male, mean age 56,77±15,76), while 30 patients were treated under GA (70% male, mean age 60,72±13,79). A total of 117709 measurements were analyzed and compared, for an overall monitoring time of 39293,66 minutes. Patients treated under GA had significantly lower average SBP (104,83±21,48 mmHg vs 138,05±22,09 mmHg, p&amp;lt;0,001), DBP (59,59±11,89 mmHg vs 76,12±12,75 mmHg, p&amp;lt;0,001), MAP (74,96±15,02 mmHg vs 97,12±15,38 mmHg, p&amp;lt;0,001). We also observed significantly lower CO (4,40±1,47 L/min vs 5,16±1,62 L/min, p&amp;lt;0,001), CI (2,22±0,71 L/min/m2 vs 2,61±0,78 L/min/m2, p&amp;lt;0,001) SV (62,37±18,04 mL/beat vs 70,65±24,95 mL/beat, p&amp;lt;0,001) and SVI (31,40±8,54 mL/beat/m2 vs 35,80±12,07 mL/beat/m2, p&amp;lt;0,001). Patients treated under GA witnessed a higher number of per-patient HE (10,53±9,16 vs 0,61±2,07, p&amp;lt;0,001), and higher HE duration (4,8±6,62 min vs 2,82±3,66, p&amp;lt;0,001). Conclusion AF ablation performed under general anesthesia is associated with significantly lower systolic, diastolic, and mean arterial pressure, reduced cardiac output, stroke volume and stroke volume index when compared to deep sedation. Patients undergoing AF ablation under GA witness higher incidence and duration of hypotensive events. CNBP is a valid tool for beat-to-beat procedural hemodynamic assessment and can help identifying and treat hypotensive events. Further studies are needed to assess the potential prognostic impact of intraprocedural hypotension during AF ablation.