Non-invasive Blood Pressure Recordings Research Articles

CardioRVAR: A New R Package and Shiny Application for the Evaluation of Closed-Loop Cardiovascular Interactions.

CardioRVAR is a new R package designed for the complete evaluation of closed-loop cardiovascular interactions and baroreflex sensitivity estimated from continuous non-invasive heart rate and blood pressure recordings. In this work, we highlight the importance of this software tool in the context of human cardiovascular and autonomic neurophysiology. A summary of the main algorithms that CardioRVAR uses are reviewed, and the workflow of this package is also discussed. We present the results obtained from this tool after its application in three clinical settings. These results support the potential clinical and scientific applications of this tool. The open-source tool can be downloaded from a public GitHub repository, as well as its specific Shiny application, CardioRVARapp. The open-source nature of the tool may benefit the future continuation of this work.

Healthy Young POLes – HYPOL database with synchronised beat-to-beat heart rate and blood pressure signals

Data sharing in medical research entails making research data available to other researchers for review, re-use, and collaboration purposes. This paper seeks to describe the HYPOL (Healthy Young POLes) database, which has been prepared for sharing. This database houses the clinical characteristics and beat-to-beat cardiovascular time series of 278 individuals of Polish descent, all aged between 19 and 30 years. The data were collected from healthy volunteers who participated in multiple projects carried out at the Department of Cardiology-Intensive Therapy research laboratory, Poznan University of Medical Sciences, Poznan, Poland. The cardiovascular time series data was obtained from non-invasive continuous finger blood pressure and ECG recordings, with sessions lasting up to 45 minutes. The HYPOL database includes an xls file detailing the main clinical characteristics and text files that capture ECG-derived RR intervals, finger systolic, diastolic, and mean blood pressure values, as well as the duration of interbeat intervals. There are data from 149 women (53.6% of the total) and 129 men. The median age of all participants studied is 24 years, their BMI was <24 kg/m2, pulse rate and blood pressure were normal. The median duration of the recordings was almost 30 minutes. In addition, we summarise selected parameters of heart rate variability (HRV) and heart rate asymmetry (HRA). The HYPOL database is available at hypol.ump.edu.pl. The download of data is free of charge after simple registration. Researchers and engineers can use the database for their purposes, except for selling it. The data can be used for testing various mathematical algorithms for HRV, HRA, blood pressure variability and asymmetry, and baroflex function.

The mechanism of impaired delayed recall verbal memory function in Parkinson's disease with orthostatic hypotension: a multiple imaging study.

Orthostatic hypotension (OH) frequently accompanies autonomic dysfunction and is an important risk factor for cognitive impairment in Parkinson's disease (PD). However, the association between different cognitive functions and OH in PD patients is not yet fully understood. This study aimed to evaluate the scores of different cognitive domains and multiple parameters using different imaging techniques on PD patients with or without OH. A total number of 31 PD patients with OH (n = 20) and without OH (n = 11) were recruited from the Department of Neurology, Beijing Xuanwu Hospital for this study. All patients underwent beat-to-beat non-invasive blood pressure recordings and an active standing test to evaluate neurogenic OH and a global neuropsychological test to assess cognitive function. All patients underwent dynamic cerebral autoregulation (dCA) measurement, brain magnetic resonance imaging (MRI), and brain 18fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). The results showed that OH patients had poor delayed recall verbal memory when compared with the PD patients without OH (1.75 ± 1.59 vs. 3.10 ± 1.73, p = 0.042). The dCA test indicated a significant difference in the right very low-frequency (VLF) gain between two groups (1.27 ± 0.17 vs. 1.10 ± 0.26, p = 0.045) and the brain 18F-FDG PET/CT indicated a significant difference in the SUV (right medial temporal lobe) to SUV (occipital lobe) ratio (0.60 ± 0.08 vs. 0.67 ± 0.11, p = 0.049). Meanwhile, these two imaging parameters were negatively correlated (p < 0.001). Furthermore, the score of a delayed recall verbal memory in the OH group was positively correlated with the right medial temporal lobe to occipital lobe ratio (p < 0.001) and was negatively correlated with the right VLF gain (p = 0.023). PD with OH patients had poor delayed recall memory, which might have been caused by the decreased metabolic dysfunction of specific medial temporal lobe due to the impaired dCA ability.

Which is the best Myocardial Work index for the prediction of coronary artery disease? A data meta-analysis.

Early diagnosis of Coronary Artery Disease (CAD) plays a key role to prevent adverse cardiac events such as myocardial infarction and Left Ventricular (LV) dysfunction. Myocardial Work (MW) indices derived from echocardiographic speckle tracking data in combination with non-invasive blood pressure recordings seems promising to predict CAD even in the absence of impairments of standard echocardiographic parameters. Our aim was to compare the diagnostic accuracy of MW indices to predict CAD and to assess intra- and inter-observer variability of MW through a meta-analysis. Electronic databases were searched for observational studies evaluating the MW indices diagnostic accuracy for predicting CAD and intra- and inter-observer variability of MW indices. Pooled sensitivity, specificity, and Summary Receiver Operating Characteristic (SROC) curves were assessed. Five studies enrolling 501 patients met inclusion criteria. Global Constructive Work (GCW) had the best pooled sensitivity (89%) followed by GLS (84%), Global Work Index (GWI) (82%), Global Work Efficiency (GWE) (80%), and Global Wasted Work (GWW) (75%). GWE had the best pooled specificity (78%) followed by GWI (75%), GCW (70%), GLS (68%), and GWW (61%). GCW had the best accuracy according to SROC curves, with an area under the curve of 0.86 compared to 0.84 for GWI, 0.83 for GWE, 0.79 for GLS, and 0.74 for GWW. All MW indices had an excellent intra- and inter-observer variability. GCW is the best MW index proving best diagnostic accuracy in the prediction of CAD with an excellent reproducibility.

1095 WHICH IS THE BEST MYOCARDIAL WORK INDEX FOR THE PREDICTION OF CORONARY ARTERY DISEASE? A DATA METANALYSIS

Abstract Background Early diagnosis of Coronary Artery Disease (CAD) plays a key role to prevent adverse cardiac events such as myocardial infarction and Left Ventricular (LV) dysfunction. Myocardial Work (MW) indices derived from echocardiographic speckle tracking data in combination with non-invasive blood pressure recordings are able to predict CAD even in the absence of impairments of standard echocardiographic parameters. Our aim was to compare the diagnostic accuracy of MW indices to predict CAD and to assess intra-observer and inter-observer variability of MW through a metanalysis. Methods Electronic databases were searched for observational studies evaluating the MW indices diagnostic accuracy for predicting CAD and intra-observer and inter-observer variability of MW indices. Pooled sensitivity, specificity, and Summary Receiver Operating Characteristic (SROC) curves were assessed. Results 5 studies enrolling 501 patients met inclusion criteria. Global Constructive Work (GCW) had the best pooled sensitivity (89%) followed by GLS (84%), Global Work Index (GWI) (82%), Global Work Efficiency (GWE) (80%) and Global Wasted Work (GWW) (75%). GWE had the best pooled specificity (78%) followed by GWI (75%), GCW (70%), GLS (68%) and GWW (61%). GCW had the best accuracy according to SROC curves, with an Area Under The Curve of 0.86 compared to 0.84 for GWI, 0.83 for GWE, 0.79 for GLS and 0.74 for GWW (Figure 1). All MW indices had an excellent intra-observer and inter-observer variability. Conclusions GCW is the best MW index proving best diagnostic accuracy in the prediction of CAD with an excellent reproducibility. Figure 1: Pooled sensitivity, pooled specificity, SROC curves and AUC of Myocardial Work indices and GLS

PM2.5 increases mouse blood pressure by activating toll-like receptor 3

Background and aimsPlenty of literature has documented that fine particulate matter (PM2.5) exposure is related to blood pressure (BP) elevation. Vascular dysfunction is the initiation of cardiovascular diseases, such as hypertension. This thesis set out to assess the role of Toll-like receptor 3 (TLR3) in the increase in BP induced by PM2.5. MethodsC57BL/6 and TLR3 deficient (TLR3-/-) male mice were randomly allocated to filtered air chamber or real-world inhaled concentrated PM2.5 chamber. BP was evaluated using non-invasive BP recordings. After euthanasia, the aortas and small mesenteric arteries (SMAs) were isolated, and vascular tone was measured using a wire myograph. Leucocytes were detached to assess myeloid-derived suppressor cells using flow cytometry. siRNA transfection was performed to silence TLR3 expression in the human vascular endothelial cells incubated with PM2.5. The gene expression levels of inflammation, adhesion molecules, and oxidative stress in the aortas were assessed by quantitative PCR. ResultsExposure to PM2.5 increased mouse BP, and TLR3 deficiency protected against PM2.5 exposure-induced BP increase. Additionally, the injury of vascular function in the aortas and SMAs was inhibited in TLR3-/- mice. The intercellular adhesion molecule-1 (ICAM-1) was attenuated in TLR3-/- mice, accompanied by the inhibition of inflammatory and oxidized genes of the aortas, such as F4/80, interleukin-6, interleukin-1 beta, and NADPH oxidase 4. In vitro, the enhanced mRNA expression of genes encoding inflammation, oxidative stress, and ICAM-1 by PM2.5 was inhibited by TLR3 silence as well. ConclusionsPM2.5 exposure increased BP via TLR3 activation and impaired vascular function.

Antihyperuricemic, Anti-Inflammatory and Antihypertensive Effect of a Dry Extract from Solidago virgaurea L. (Asteraceae)

Solidago virgaurea L. is a perennial plant used in European traditional medicine as a diuretic or a remedy for inflammatory conditions of the urinary tract but also for gout, especially in the Balkans. The present study was focused on a preclinical, in vivo evaluation of antihyperuricemic, anti-inflammatory, and antihypertensive effects of a dry extract from S. virgaurea L. (ESV). Colorimetric and HPLC–MS techniques were used to identify the main chemical constituents of ESV. Antihyperuricemic effect of ESV was assessed in a rat model of hyperuricemia induced by the administration of potassium oxonate. Antihypertensive effect of ESV was evaluated in hyperuricemic rats by monitoring systolic blood pressure with a non-invasive blood-pressure recording system. The anti-inflammatory effect of ESV was tested using a rat model of paw edema. The main chemical constituents of ESV were rutin and phenolic acids represented by chlorogenic and caffeic acid. ESV demonstrated significant antihyperuricemic effects in rats due to an uricosuric mechanism. Additionally, ESV reduced the progression of arterial hypertension in hyperuricemic rats and also showed anti-inflammatory properties slightly inferior to diclofenac. The results suggest that ESV could be a natural remedy for the treatment of gout and protection against endothelial dysfunction caused by hyperuricemia.

Comparison of global left ventricular myocardial work indices at baseline and after 3 months of st-segment elevation myocardial infarction

Abstract Background Global left ventricular myocardial work indices (GLVMWI) are derived from speckle tracking echocardiographic strain data in combination with non-invasive blood pressure recordings. Global work index (GWI), global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE) are derived from these measures. GLVMWI in ST-segment elevation myocardial infarction (STEMI) remains unexplored and comparison between measures of GLVMWI at index event (baseline) and follow-up is unknown. Purpose To assess the evolution in GLVMWI in STEMI patients from baseline (index infarct) to 3 months' follow-up. Methods This retrospective study included 350 patients (265 men, mean age: 61±10 years) with STEMI treated with primary percutaneous coronary intervention and optimal, guideline-based medical therapy. Clinical variables, echocardiographic measures and GLVMWI were recorded at baseline and 3 months follow-up. Results Left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), GWI, GCW and GWE improved significantly at 3 months follow-up with no significant difference in GWW (Table). These findings suggest that the impaired values of GLVMWI at baseline are related to stunning after STEMI and they recover at 3 months follow-up without further deterioration in GWW, which probably reflects irreversible myocardial damage. Conclusions In STEMI patients treated with primary percutaneous coronary intervention and optimal guideline-based medical therapy, GLVMWI assessed by speckle tracking strain echocardiography are significantly improved at 3 months follow-up, without significant changes in GWW. GLVMWI therefore have the potential to identify reversible and irreversible components of post-infarct myocardial damage. Funding Acknowledgement Type of funding source: Other. Main funding source(s): European Society of Cardiology Research Grant

Regional left ventricular myocardial work index in culprit territory predicts early left ventricular remodelling in patients with st-segment elevation myocardial infarction

Abstract Background The association between left ventricular (LV) myocardial work index (LVMWI) derived from speckle tracking echocardiographic strain data in combination with non-invasive blood pressure recordings and adverse LV dilatation i.e. remodelling has not been evaluated. Purpose To assess the predictive value of regional LVMWI for LV remodelling at baseline echocardiography in patients with ST-segment elevation myocardial infarction (STEMI). Methods This retrospective study included 350 patients (265 men, mean age: 61±10 years) with STEMI treated with primary percutaneous coronary intervention and optimal medical therapy. Clinical variables, conventional echocardiographic parameters, global and segmental measures of LVMWI were recorded at baseline. The primary endpoint was early LV remodelling defined as increase in LV end-diastolic volume (LVEDV) ≥20% at 3 months after the index event. Results Eighty-seven patients (24.9%) presented with early LV remodelling. The global and regional LVMWI in the culprit territory were significantly lower in patients with early LV remodelling. Univariate and multivariate logistic regression analyses were performed to identify predictors of early LV remodelling. At the index event, troponin I peak, LVEDV and LVMWI in the culprit territory were independently associated with early LV remodelling (Table). Conclusions In STEMI patients treated with primary percutaneous coronary intervention and optimal medical therapy, the regional LVMWI in the culprit territory at echocardiography before discharge is independently associated with troponin I peak and LVEDV in predicting early LV remodelling. Funding Acknowledgement Type of funding source: Other. Main funding source(s): European Society of Cardiology

A Novel Automated Blood Pressure Estimation Algorithm Using Sequences of Korotkoff Sounds.

The use of automated non-invasive blood pressure (NIBP) measurement devices is growing, as they can be used without expertise, and BP measurement can be performed by patients at home. Non-invasive cuff-based monitoring is the dominant method for BP measurement. While the oscillometric technique is most common, a few automated NIBP measurement methods have been developed based on the auscultatory technique. Amongst artificial intelligence (AI) techniques, deep learning has received increasing attention in different fields due to its strength in data classification, and feature extraction problems. This paper proposes a novel automated AI-based technique for NIBP estimation from auscultatory waveforms (AWs) based on converting the NIBP estimation problem to a sequence-to-sequence classification problem. To do this, a sequence of segments was first formed by segmenting the AWs, and their corresponding decomposed detail, and approximation parts obtained by wavelet packet decomposition method, and extracting features from each segment. Then, a label was assigned to each segment, i.e. (i) between systolic, and diastolic segments, and (ii) otherwise, and a bidirectional long short term memory recurrent neural network (BiLSTM-RNN) was devised to solve the resulting sequence-to-sequence classification problem. Adopting a 5-fold cross-validation scheme, and using a data base of 350 NIBP recordings gave an average mean absolute error of 1.7±3.7 mmHg for systolic BP (SBP), and 3.4 ±5.0 mmHg for diastolic BP (DBP) relative to reference values. Based on the results achieved, and comparisons made with the existing literature, it is concluded that the proposed automated BP estimation algorithm based on deep learning methods, and auscultatory waveform brings plausible benefits to the field of BP estimation.

Left ventricular myocardial work in the culprit vessel territory and impact on left ventricular remodelling in patients with ST-segment elevation myocardial infarction after primary percutaneous coronary intervention

Adverse left ventricular (LV) remodelling after ST-segment elevation myocardial infarction (STEMI) is associated with poor outcome. Global and regional LV myocardial work (LVMW) derived from speckle tracking echocardiographic strain data in combination with non-invasive blood pressure recordings could provide information for prediction of LV remodelling after STEMI. The aim of the study was to assess the predictive value of global and regional LVMW for LV remodelling before discharge in patients with STEMI. Three-hundred and fifty STEMI patients treated with primary percutaneous coronary intervention (PCI) were included [265 men (76%), mean age: 61 ± 10 years]. Clinical variables, conventional echocardiographic parameters, global and regional measures of myocardial work index (MWI), and myocardial work efficiency were recorded before discharge. The primary endpoint was early LV remodelling defined as increase in LV end-diastolic volume (LVEDV) ≥20% at 3 months after STEMI. Eighty-seven patients (25%) showed early LV remodelling. The global and regional LVMW in the culprit territory were significantly lower in patients with early LV remodelling. Peak troponin I (OR 1.109, 95% CI 1.046-1.177; P = 0.001), LVEDV (OR 0.972, 95% CI 0.959-0.984; P < 0.001) and regional MWI in the culprit vessel territory (OR 0.602, 95% CI 0.383-0.945; P = 0.027) were independently associated with early LV remodelling. In STEMI patients treated with primary PCI and optimal medical therapy, the regional cardiac work index in the culprit vessel territory before discharge is independently associated with early adverse LV remodelling.

Protective Effects of Thymus schimperi and Moringa stenopetala Leaf Extracts on Arterial Blood Pressure and Urine Protein Level in Pre-eclampsia Rat Models

Background: Pre-eclampsia (PE) is a common hypertensive disorder during pregnancy and one of the leading causes of perinatal mortality and morbidity. There is no curative modern drug to treat PE. Therefore, researches done on traditional medications have paramount importance in discovering therapeutic and /or protective agents from plant materials. In Ethiopia, there are claims that some indigenous medicinal plants such as Thymus and Moringa can have potential protective functions against PE. The aim of this study was to prove the claims.&#x0D; Methods: Experiments were performed to investigate the effects of aqueous leaf extracts of Thymus schimperi (ALETS) and Moringa stenopetala (ALEMS) on PE rat models induced by nitro-L-arginine methyl ester (L-NAME); a nitric oxide synthase inhibitor. A non-invasive tail cuff blood pressure recorder (Model 179 Amplifier, IITC INC, Life Science Instruments, Woodland Hills, California) was used to determine the arterial blood pressure from rat tail. Urine analysis to determine protein levels was performed using a dipstick, semi-qualitative method as per manufacturer’s instructions (CYBO DFI Korea).&#x0D; Results: ALETS treated PE rat models showed significantly reduced mean arterial blood pressure (MAP) in mmHg; 108±3 (P&lt;0.05), 105±1 (P&lt;0.01) and 99±2 (P&lt;0.01); also the same pattern of results were seen in ALEMS treated PE groups with MAP of 106±1 (P&lt;0.05), 103±1 (P&lt;0.05) and 101±1 (P&lt;0.05) at daily doses of 250 mg/kg, 500 mg/kg and 1000 mg/kg, respectively, compared to untreated case group that had 123±3.7 mmHg at gestation day (GD) 19 . Untreated PE rat models showed significant proteinuria (2000±20 mg/L) throughout the gestation period; while PE rat models treated with either ALETS or ALEMS had significantly reduced (p&lt;0.05) proteinuria in dose dependent pattern (150±15 mg/L) at a dose of 1 gm/kg for each plant extract at GD 19.&#x0D; Conclusion: Aqueous leaf extracts of either Thymus schimperi or Moringa stenopetala might reduce and control arterial pressure in PE rat models in a dose dependent manner. The extracts also could reduce level of proteinuria in the same pattern. Further investigation should, however, be carried out to confirm their uses in prevention and/or treatment of pregnancy-induced hypertension among human cases.

27 Cerebral Autoregulation Associated with Falls in Older Persons with Orthostatic Hypotension?

Abstract Background It is considered well-established that orthostatic hypotension (OH) is associated with falls, population-based studies have found that a large proportion of community-dwelling older adults fulfill the criteria for OH without experiencing falls. It is therefore postulated that older individuals with OH may only experience fall if cerebral autoregulation, which is the mechanism by which the brain blood flow is maintained constant through a autoregulatory range, is impaired. Objective To evaluate the relationship between cerebral autoregulation and OH in older individuals with and without a history of falls. Method Individuals aged 3 60 years were recruited from medical clinics, by word of mouth, and from existing research registries. Baseline sociodemographics, detailed medical history and medication history were obtained. Bilateral middle cerebral artery (MCA) blood flow were recorded using transcranial Doppler ultrasound (TCD) synchronized with non-invasive continuous blood pressure and ECG recordings. Synchronized brain blood flow signals, heart trace and blood pressure signals were first recorded during 10 minutes’ supine rest. Participants were then be asked to perform a standard set of mathematical calculations, a Valsalva maneuver and to stand up from a seated position. Results 36 participants have been evaluated to date (13 fallers, 23 non-Fallers). There is no statistically significant difference in gender, ethnicity or height and weight between groups. Fluctuations in MCA flow velocity were observed with spontaneous fluctuations in blood pressure at rest and with induced blood pressure changes during the challenge maneuvers. Visual inspection of the signals obtained suggested that changes in MCA flow velocity were more marked among fallers and non-fallers. Conclusion Synchronization of cerebral blood flow and continuous blood pressure signals opens up numerous new possibilities in research and clinical practice. Our preliminary findings suggest that cerebral autoregulation does play a role in determining the presence of symptomats in older individuals with OH.

Blood Pressure Estimation From Time-Domain Features of Oscillometric Waveforms Using Long Short-Term Memory Recurrent Neural Networks

This article presents a novel method for estimating systolic blood pressure (SBP) and diastolic blood pressure (DBP) from time-domain features extracted from oscillometric waveforms (OWs) using a long short-term memory (LSTM) recurrent neural network (RNN) method. First, we extract seven time-domain features from each cycle of OW, including the cuff pressure, the cardiac period, the trough-to-peak amplitude of OW, the time between the trough and the peak of the OW, the slopes of the oscillometric waveform envelope (OWE), and the maximum upslope of individual OWs. Second, we locate each feature vector in an noninvasive blood pressure (NIBP) record in one of three different phases (classes), namely, presystolic (PS), between systolic and diastolic (BSD), and after diastolic (AD), and form a target sequence. Then, we propose an LSTM-RNN approach to effectively learn the complex nonlinear relationship between the feature vector sequences and the target sequence. The SBP and DBP points are then obtained by mapping the beats at which the network output sequence switches from PS phase to BSD phase and from BSD phase to AD phase, respectively, to the deflation curve. Adopting a tenfold cross-validation scheme and using a database of 350 NIBP recordings gave an average mean error of −1.2 ± 5.9 mmHg for SBP and 1.8 ± 8.8 mmHg for DBP relative to reference values derived from a visual method of determining SBP and DBP. The proposed RNN-based approach uses all time-domain features available from each NIBP recording and can outperform traditional methods in blood pressure (BP) estimation.

Prognostic implications of global, left ventricular myocardial work efficiency before cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) restores mechanical efficiency to the failing left ventricular (LV) by resynchronization of contraction. Global, LV myocardial work efficiency (GLVMWE) can be quantified non-invasively with echocardiography. The prognostic implication of GLVMWE remains unexplored, and we therefore related GLVMWE before CRT to long-term prognosis. Data were analysed from an ongoing registry of patients with Class I indications for CRT. GLVMWE was defined as the ratio of constructive work in all LV segments, divided by the sum of constructive and wasted work in all LV segments, as a percentage. It was derived from speckle tracking strain echocardiography and non-invasive blood pressure measurements, taken pre-CRT. Patients were dichotomized according to baseline, median GLVMWE [75%; interquartile range (IQR) 66-81%]. A total of 153 patients (66 ± 10 years, 72% male, 48% ischaemic heart disease) were analysed. After a median follow-up of 57 months (IQR 28-76 months), 31% of patients died. CRT recipients with less efficient baseline energetics (GLVMWE <75%) demonstrated lower event rates than patients with more efficient baseline energetics (GLVMWE ≥75%) (log-rank test, P = 0.029). On multivariable analysis, global LV wasted work ratio <75% pre-CRT was independently associated with a decreased risk of all-cause mortality (hazard ratio 0.48, 95% confidence interval 0.25-0.92; P = 0.027), suggesting that the potential for improvement in LV efficiency is important for CRT benefit. GLVMWE can be derived non-invasively from speckle tracking strain echocardiography and non-invasive blood pressure recordings. A lower GLVMWE before CRT is independently associated with improved long-term outcome.

Blood Pressure Estimation From Beat-by-Beat Time-Domain Features of Oscillometric Waveforms Using Deep-Neural-Network Classification Models

In general, existing machine learning based approaches, developed for systolic and diastolic blood pressure (SBP and DBP) estimation from oscillometric waveforms (OWs), employ features extracted from the OW envelope (OWE) alone and ignore important beat-by-beat (BBB) features which represent fundamental physical properties of the entire non-invasive blood pressure (NIBP) measurement system. Unlike the existing literature, this paper proposes a novel deep-learning based method for BP estimation trained with BBB time-domain features extracted from OWs. First, we extract six time-domain features from each beat of the OW, relative to the preceding beat. Second, using the extracted BBB features along with the corresponding cuff pressures, we form a feature vector for each OW beat and locate it in one of three different classes, namely pre-systolic (PS), between systolic and diastolic (BSD) and after diastolic (AD). We then devise a deep-belief network (DBN)-deep neural network (DNN) classification model as well as a novel artificial feature extraction method for estimating SBP and DBP from feature vectors extracted from OWs and their corresponding deflation curves. The proposed DBN-DNN classification approach can effectively learn the complex nonlinear relationship between the artificial feature vectors and target classes. The SBP and DBP points are then obtained by mapping the beats at which the network output sequence switches from PS phase to BSD phase and from BSD phase to AD phase, respectively, to the deflation curve. Adopting a 5-fold cross-validation scheme and using a data base of 350 NIBP recordings gave an average mean absolute error of 1.1±2.9 mmHg for SBP and 3.0±5.6 mmHg for DBP relative to reference values. We experimentally show that the proposed DBN-DNN-based classification algorithm trained with BBB time-domain features can outperform traditional deep-learning based methods for BP estimation trained with features extracted only from OWEs.

Continuous Non-Invasive Blood Pressure Measurement Using Pulse Transit Time in Children and Adolescents

As an alternative to ambulatory 24-h blood pressure monitors, the continuous, non-invasive blood pressure recording using pulse transit time (PTT) was compared with both oscillometric and intra-arterial measurement. In 144 pediatric patients (9.4±5.2 years) acute blood pressure was determined using three different methods of measurement. In 57 patients (11.4±4.9 years) of the pediatric normal ward, the blood pressure was simultaneously determined continuously by means of PTT compared to the intermittent oscillometric long-term measurement. In 9 patients (9.8±6.8 years) of the pediatric intensive care unit with continuous intra-arterial blood pressure measurement, the blood pressure was measured in parallel by means of PTT. Compared to the gold standard sphygmomanometry, mean systolic blood pressure values were comparable to 2 different oscillometric devices, but in the case of diastolic pressure measurement the pressure values were significantly lower or higher than with sphygmomanometry and auscultation. The results of the non-invasive comparative long-term measurements showed better correlations for systolic rather than diastolic pressure. Similar results were obtained comparing the direct intra-arterial blood pressure measurement with the SOMNOtouch™ NIBP device which measures blood pressure using the PTT. Continuous, indirect blood pressure recording using pulse transit time provides good correlations to the reference measurements for long-term measurement of blood pressure in children and adolescents and appears to be a usable method to measure the blood pressure of children especially at rest.

Beat-to-Beat Variability of Ventricular Action Potential Duration Oscillates at Low Frequency During Sympathetic Provocation in Humans.

Background: The temporal pattern of ventricular repolarization is of critical importance in arrhythmogenesis. Enhanced beat-to-beat variability (BBV) of ventricular action potential duration (APD) is pro-arrhythmic and is increased during sympathetic provocation. Since sympathetic nerve activity characteristically exhibits burst patterning in the low frequency range, we hypothesized that physiologically enhanced sympathetic activity may not only increase BBV of left ventricular APD but also impose a low frequency oscillation which further increases repolarization instability in humans.Methods and Results: Heart failure patients with cardiac resynchronization therapy defibrillator devices (n = 11) had activation recovery intervals (ARI, surrogate for APD) recorded from left ventricular epicardial electrodes alongside simultaneous non-invasive blood pressure and respiratory recordings. Fixed cycle length was achieved by right ventricular pacing. Recordings took place during resting conditions and following an autonomic stimulus (Valsalva). The variability of ARI and the normalized variability of ARI showed significant increases post Valsalva when compared to control (p = 0.019 and p = 0.032, respectively). The oscillatory behavior was quantified by spectral analysis. Significant increases in low frequency (LF) power (p = 0.002) and normalized LF power (p = 0.019) of ARI were seen following Valsalva. The Valsalva did not induce changes in conduction variability nor the LF oscillatory behavior of conduction. However, increases in the LF power of ARI were accompanied by increases in the LF power of systolic blood pressure (SBP) and the rate of systolic pressure increase (dP/dtmax). Positive correlations were found between LF-SBP and LF-dP/dtmax (rs = 0.933, p < 0.001), LF-ARI and LF-SBP (rs = 0.681, p = 0.001) and between LF-ARI and LF-dP/dtmax (rs = 0.623, p = 0.004). There was a strong positive correlation between the variability of ARI and LF power of ARI (rs = 0.679, p < 0.001).Conclusions: In heart failure patients, physiological sympathetic provocation induced low frequency oscillation (~0.1 Hz) of left ventricular APD with a strong positive correlation between the LF power of APD and the BBV of APD. These findings may be of importance in mechanisms underlying stability/instability of repolarization and arrhythmogenesis in humans.

A cross-sectional analytical study on the influence of age in the precision and accuracy of non-invasive blood pressure recording compared to invasive intra-arterial pressure recording

Background: Even after 115 years after the invention of Riva-Rocci Sphygmomanometer, the technique which shows the maximal accuracy of blood pressure (BP) measurement remains elusive. Currently, non-invasive BP (NIBP) recording is commonly done worldwide. Yet, intra-arterial pressure (IAP) recording gives a beat to beat accurate recording of one’s BP. Aims and Objectives: The aims of this study are as follows: (1) To compare NIBP with IAP in various age groups and (2) to study the influence of age in the accuracy of NIBP recording. Materials and Methods: A total of 98 patients aged 30–75 years posted for a coronary angiogram (CAG) were recruited for the study and divided into 3 groups based on age (Group I 30–45, Group II 46–60, and Group III 61–75). Two sets of NIBP and corresponding IAP (radial and aortic arterial pressures) were recorded during CAG. Paired t-test to compare the NIBP with corresponding IAP and ANOVA with post-hoc Bonferroni to check the influence of age with the accuracy of recording were done. Results: NIBP differed significantly with the corresponding IAP when analyzed by paired t-test (P < 0.0001). Multiple comparisons between three age groups and the pressure difference by ANOVA were done. Age Groups I and III (30–45 years and 61–75 years) both systolic NIBPI versus radial artery pressure (P = 0.013) as well as diastolic NIBP II versus arterial blood pressure (ABP) (P = 0.053) pressure comparison were widely different. Age Groups II (46–60 years) and III (61–70 years) varied in the diastolic NIBPII versus ABP comparison with P = 0.050. The results thus indicate that there is discrepancy of manual BP versus IAP with an increasing trend with the advancement of age. Conclusion: Thus, the results indicate that there is a discrepancy of NIBP versus IAP with NIBP showing higher values which widens with advancing age.

P2.08-013 Integrated Complementary ‘Energy' Therapy Improves Patient Experience of a Lung Cancer Diagnosis: Topic: Other

40,000 people were diagnosed with Lung cancer in the UK in 2012. Invasive procedures and repeated clinic visits compound the stress of diagnosis. This study reports a non pharmacological approach to improving patient experience. Energy therapies exist in many medical traditions healing through interaction with the patient’s biofield –the invisible psychophysical entity including the body but extending beyond it in the form of energy. In this case a technique where a trained therapist uses light touch or hands held a short distance from the subject to transfer energy to the recipient and bring a greater sense of well being. 112 patients were invited to receive an ‘Energy therapy’ session alongside their clinic appointment or bronchoscopy. The primary endpoint was reduction in anxiety. Pre and post treatment data was collected from self completed anonamised questionnaires using a 0-10 scale for subjective variables and non-invasive blood pressure recordings. Data was analysed using a students t-test. 83 patients took part in the study. 60% female, mean age 62.69. Table 1 summarises the questionnaire scores. Patients reported statistically significant reduction in anxiety, tension, stress and pain following a session of energy therapy. There was also an improvement in mood and sense of calm.Tabled 1Change in mood scores before and after Energy therapyVariable ( 0= best 10= worst)Pre-treatment mean score N = 80Post-treatment mean score N= 80Degree of change (p)Anxiety (Do you feel anxious)5.452.33.15 (<0.001)Calm (do you feel calm)4.891.713.175 (<0.001)Tension (do you have tension in your body?)5.232.163.062 (<0.001)Stress (do you feel stressed)5.462.093.375 (<0.001)Mood (do you feel low in mood)4.682.352.35 (<0.001)Pain (are you in pain)3.401.731.675 (<0.001)Systolic BP (n=78)135.28131.154.12 (0.007 Open table in a new tab The role of complementary therapy in cancer care has long been recognised internationally and there are reports of Energy therapy used synergistically in palliative care and management of chemotherapy side effects [i]. We believe this is the first study to look at the role of complementary Energy therapy in supporting patients undergoing a cancer diagnosis. Complementary ‘energy’ therapy is a powerful tool to significantly reduce anxiety, tension and boost mood for patients undergoing investigation and treatment for lung cancer [i] Jain S, Mills P: Biofield therapies: Helpful or full of hype? A best evidence synthesis. Int J Behav Med 17:1–16, 2010