Towards continuous non-invasive blood pressure measurements-interpretation of the vasculature response to cuff inflation.

Blood pressure (BP) surrogates, such as pulse transit time (PTT) or pulse arrival time (PAT), have been intensively explored with the goal of achieving cuffless, continuous, and accurate BP inference. In order to estimate BP, a one-point calibration strategy between PAT and BP is typically used. Recent research focuses on advanced calibration procedures exploiting the cuff inflation process to improve calibration robustness by active and controlled modulation of peripheral PAT, as measured via plethysmograph (PPG) and electrocardiogram (ECG) combination.

New Hemodynamic Parameters in Peri-Operative and Critical Care-Challenges in Translation.

Hemodynamic monitoring technologies are evolving continuously-a large number of bedside monitoring options are becoming available in the clinic. Methods such as echocardiography, electrical bioimpedance, and calibrated/uncalibrated analysis of pulse contours are becoming increasingly common. This is leading to a decline in the use of highly invasive monitoring and allowing for safer, more accurate, and continuous measurements.

On the value of MRI for improved understanding of cuff-based oscillometric measurements.

Blood pressure (BP) is a key parameter in critical care and in cardiovascular disease management. BP is typically measured via cuff-based oscillometry. This method is highly inaccurate in hypo- and hypertensive patients.

Personalization of pulse arrival time based blood pressure surrogates through single spot check measurements.

Objective: We investigate the effect of selective single parameter personalization on the performance of multi-parameter models for pulse arrival time (PAT) based blood pressure (BP) surrogates.

Methods: Our data set stems from 15 surgery patients, and we selected from each patient 5 segments of 30 min length each. We evaluate the root mean squared BP tracking error of the two models with and without single parameter personalization.

Modulation of pulse travel and blood flow during cuff inflation- An experimental case study.

The blood pressure (BP) cuff can be used to modulate blood flow and propagation of pressure pulse along the artery. In our previous work, we researched methods to adapt cuff modulation techniques for pulse transit time vs. BP calibration and for measurement of other hemodynamic indices of potential interest to critical care, such as arterial compliance.

Modulation of Pulse Propagation and Blood Flow via Cuff Inflation-New Distal Insights.

In standard critical care practice, cuff sphygmomanometry is widely used for intermittent blood pressure (BP) measurements. However, cuff devices offer ample possibility of modulating blood flow and pulse propagation along the artery. We explore underutilized arrangements of sensors involving cuff devices which could be of use in critical care to reveal additional information on compensatory mechanisms.

Optimized non-uniform sampling of blood pressure time series from the operating room.

Objective: We investigate an optimized non-uniform sampling strategy for blood pressure time series from the operating room (OR). Our aim is to obtain an approximate bound on the achievable reconstruction fidelity given an average sampling rate constraint.

Methods: Our data set consists of 117 hours of recordings of continuous invasive blood pressure from 28 surgery patients.

Method for measurement of arterial compliance by fusion of oscillometry and pulse wave velocity.

Up until now estimation of arterial compliance has been performed either by analysis of arterial pressure changes with respect to volume changes or by inference based on pulse wave velocity (PWV). In this study we demonstrate the possibility of an approach to assess arterial compliance by fusing the two information sources namely the pressure/volume relationship obtained from oscillography and PWV data. The goal is to assess arterial properties easily and robustly, enhancing current hemodynamic monitoring.

A modelling framework for assessment of arterial compliance by fusion of oscillometry and pulse wave velocity information.

Background And Objectives: Measurement of arterial compliance is recognized as important for clinical use and for enabling better understanding of circulatory system regulation mechanisms. Estimation of arterial compliance involves either a direct measure of the ratio between arterial volume and pressure changes or an inference from the pulse wave velocity (PWV). In this study we demonstrate an approach to assess arterial compliance by fusion of these two information sources.

Insights into oscillometry: An Experimental Study for Improvement of Cuff-Based Blood Pressure Measurement Technology.

Non-invasive blood pressure (BP) measurements are usually performed by means of an empirical interpretation of arterial oscillations recorded via cuff based oscillometic methods. Extensive effort has been put into development of a theoretical treatment of oscillometry aiming at more accurate BP estimations and measurement of additional hemodynamic parameters. However, oscillometry is still basically a heuristic method for BP inference.

Feasibility of in-vivo estimation of the brachial artery area-pressure relation from CINE and real-time MRI during upper arm cuff inflations.

Objective: We investigate the basic feasibility of estimating the brachial artery area-pressure relationship from MRI data obtained during pressure cuff inflations in-vivo.

Methods: We acquired cross-sectional real-time MR images and cardiac-gated CINE MR images from the upper arm of a single male subject at rest during supra-systolic pressure cuff inflations and deflations. We estimate from the MR images the lumen area changes of the brachial artery, and, simultaneously, from the cuff pressure the systemic blood pressure of the subject.

On detection of spontaneous pulse by photoplethysmography in cardiopulmonary resuscitation.

Objective: This work investigates the potential of photoplethysmography (PPG) to detect a spontaneous pulse from the finger, nose or ear in order to support pulse checks during cardiopulmonary resuscitation (CPR).

Methods: In a prospective single-center cross-sectional study, PPG signals were acquired from cardiac arrest victims who underwent CPR. The PPG signals were analyzed and compared to arterial blood pressure (ABP) signals as a reference during three distranaisco; Date: 2/2/2020; Time:18:44:23inct phases of CPR: compression pauses, on-going compressions and at very low arterial blood pressure.

Sympathetic and Parasympathetic Coactivation Induces Perturbed Heart Rate Dynamics in Patients with Paroxysmal Atrial Fibrillation.

BACKGROUND Recent evidence indicates that sympathetic/parasympathetic coactivation (CoA) is causally linked to changes in heart rate (HR) dynamics. Whether this is relevant for patients with atrial fibrillation (AF) is unknown. MATERIAL AND METHODS In patients with paroxysmal AF (n=26) and age-matched controls, (n=10) we investigated basal autonomic outflow and HR dynamics during separate sympathetic (cold hand immersion) and parasympathetic activation (O2-inhalation), as well as during CoA (cold face test).

Artifact detection in accelerometer signals acquired from the carotid.

Manual pulse palpation is the common procedure to assess pulse in unconscious patients. This is an error prone procedure during cardiopulmonary resuscitation and therefore automatic pulse detection techniques are being investigated. Accelerometry is an interesting sensing modality for this type of applications.

Comparison of pulse wave velocity derived from accelerometer and reflective photo-plethysmography signals placed at the carotid and femoral artery.

Carotid - femoral pulse wave velocity is an established measure to assess cardiovascular risk and an interesting surrogate parameter towards non-invasive continuous blood pressure inference. Due to progress in sensing technologies for wearable wrist worn sensors, there are low cost sensor combinations of photo-plethysmography and high fidelity accelerometers available offering access to pulse information from larger arteries complemented by blood volume changes in the superficial tissue. In this work we compare pulse wave velocities derived from accelerometer and reflective photo-plethysmography signals placed at the carotid and femoral artery.

Cuff-pressure induced PAT changes - modelling and experimental verification towards calibration of blood pressure surrogates.

Arterial Blood Pressure (ABP) is one of the most often measured vital parameters in daily clinical practice. State-of-the-Art non-invasive ABP measurement technologies have obvious limitations and are still mainly based on uncomfortable techniques by complete or partial occlusions of arteries. Additionally, embodiments are bulky, difficult to apply for the layman, or provide only intermittent measurements.

Towards an algorithm for automatic accelerometer-based pulse presence detection during cardiopulmonary resuscitation.

Manual palpation is still the gold standard for assessment of pulse presence during cardiopulmonary resuscitation (CPR) for professional rescuers. However, this method is unreliable, time-consuming and subjective. Therefore, reliable, quick and objectified assessment of pulse presence in cardiac arrest situations to assist professional rescuers is still an unmet need.

Can PPG be used for HRV analysis?

Heart rate variability (HRV) represents one of the most promising markers of the autonomic nervous system (ANS) regulation. However, it requires the acquisition of the ECG signal in order to reliably detect the RR intervals, which is not always easily and comfortably available in personal health applications. Additionally, due to progress in single spot optical sensors, photoplethysmography (PPG) is an interesting alternative for heartbeat interval measurements, since it is a more convenient and a less intrusive measurement technique.

Systolic blood pressure estimation using PPG and ECG during physical exercise.

In this work, a model to estimate systolic blood pressure (SBP) using photoplethysmography (PPG) and electrocardiography (ECG) is proposed. Data from 19 subjects doing a 40 min exercise was analyzed. Reference SBP was measured at the finger based on the volume-clamp principle.

Pulse detection with a single accelerometer placed at the carotid artery: Performance in a real-life diagnostic test during acute hypotension.

Pulse detection via palpation is a basic and essential procedure in daily medical practice. We have been investigating the performance of a single accelerometer placed above the carotid artery, which is one of the recommended locations for manual palpation. A low-cost sensor attached by an adhesive measures accelerations due to carotid dilatations and whole body vibrations.

Assessment of cardiovascular function from multi-Gaussian fitting of a finger photoplethysmogram.

Monitoring of cardiovascular function on a beat-to-beat basis is fundamental for protecting patients in different settings including emergency medicine and interventional cardiology, but still faces technical challenges and several limitations. In the present study, we propose a new method for the extraction of cardiovascular performance surrogates from analysis of the photoplethysmographic (PPG) signal alone.We propose using a multi-Gaussian (MG) model consisting of five Gaussian functions to decompose the PPG pulses into its main physiological components.

Real-Time Prediction of Neurally Mediated Syncope.

Neurally mediated syncope (NMS) patients suffer from sudden loss of consciousness, which is associated with a high rate of falls and hospitalization. NMS negatively impacts a subject's quality of life and is a growing cost issue in our aging society, as its incidence increases with age. In this paper, we present a solution for prediction of NMS, which is based on the analysis of the electrocardiogram (ECG) and photoplethysmogram (PPG) alone.

A novel multi-parametric algorithm for faint prediction integrating indices of cardiac inotropy and vascular tone.

Neurally medicated syncope (NMS) patients suffer from sudden loss of consciousness, which is associated with a high rate of falls and hospitalization. NMS negatively impacts a subject's quality of life and is a growing cost issue for the healthcare systems in particular since mainly elderly are at risk of NMS in our aging societies. In the present paper we present an algorithm for prediction of NMS, which is based on the analysis of the electrocardiogram (ECG) and photoplethysmogram (PPG) signals.

Detection of motion artifact patterns in photoplethysmographic signals based on time and period domain analysis.

The presence of motion artifacts in photoplethysmographic (PPG) signals is one of the major obstacles in the extraction of reliable cardiovascular parameters in continuous monitoring applications. In the current paper we present an algorithm for motion artifact detection based on the analysis of the variations in the time and the period domain characteristics of the PPG signal. The extracted features are ranked using a normalized mutual information feature selection algorithm and the best features are used in a support vector machine classification model to distinguish between clean and corrupted sections of the PPG signal.