A Tactile-Pattern-Integrated Sensing Window for More Consistent Photoplethysmography (PPG) Measurements.

We have demonstrated a tactile-pattern-integrated sensing window for more consistent photoplethysmogram (PPG) measurements. The pattern is composed of two tiny bumps that measure 500μm in diameter and 300μm in height and allow users to position their finger pulps more consistently on the sensing window over different measurement occasions, simply by following their tactile sensation. We experimentally compared the tactile pattern window to a flat window (without any bumps) for 5 test subjects and found that the sensing window with the tactile pattern significantly helped users obtain more consistent PPG signals than the flat window (p < 0.

Posture-Dependent Variability in Wrist Ballistocardiogram-Photoplethysmogram Pulse Transit Time: Implication to Cuff-Less Blood Pressure Tracking.

Objective: Toward the ultimate goal of robust cuff-less blood pressure (BP) tracking with wrist wearables against postural changes, the goal of this work was to investigate posture-dependent variability in pulse transit time (PTT) measured with ballistocardiogram (BCG) and photoplethysmogram (PPG) signal pair at the wrist.

Methods: BCG and PPG signals were acquired from 25 subjects under the combination of 3 body (standing, sitting, and supine) and 3 arm (vertical in head-to-foot direction, placed on the chest, and holding a shoulder) postures. PTT was computed as the time interval between the BCG J wave and the PPG foot, and the impact of the 9 postures on PTT was analyzed by invoking an array of possible physical mechanisms.

A Unified Approach to Wearable Ballistocardiogram Gating and Wave Localization.

Objective: Toward the ultimate goal of cuff-less blood pressure (BP) trend tracking via pulse transit time (PTT) using wearable ballistocardiogram (BCG) signals, we present a unified approach to the gating of wearable BCG and the localization of wearable BCG waves.

Methods: We present a unified approach to localize wearable BCG waves suited to various gating and localization reference signals. Our approach gates individual wearable BCG beats and identifies candidate waves in each wearable BCG beat using a fiducial point in a reference signal, and exploits a pre-specified probability distribution of the time interval between the BCG wave and the fiducial point in the reference signal to accurately localize the wave in each wearable BCG beat.

The Potential of Wearable Limb Ballistocardiogram in Blood Pressure Monitoring via Pulse Transit Time.

The goal of this study was to investigate the potential of wearable limb ballistocardiography (BCG) to enable cuff-less blood pressure (BP) monitoring, by investigating the association between wearable limb BCG-based pulse transit time (PTT) and BP. A wearable BCG-based PTT was calculated using the BCG and photoplethysmogram (PPG) signals acquired by a wristband as proximal and distal timing reference (called the wrist PTT). Its efficacy as surrogate of BP was examined in comparison with PTT calculated using the whole-body BCG acquired by a customized weighing scale (scale PTT) as well as pulse arrival time (PAT) using the experimental data collected from 22 young healthy participants under multiple BP-perturbing interventions.

Physiological Association between Limb Ballistocardiogram and Arterial Blood Pressure Waveforms: A Mathematical Model-Based Analysis.

By virtue of its direct association with the cardiovascular (CV) functions and compatibility to unobtrusive measurement during daily activities, the limb ballistocardiogram (BCG) is receiving an increasing interest as a viable means for ultra-convenient CV health and disease monitoring. However, limited insights on its physical implications have hampered disciplined interpretation of the BCG and systematic development of the BCG-based approaches for CV health monitoring. In this study, a mathematical model that can predict the limb BCG in responses to the arterial blood pressure (BP) waves in the aorta was developed and experimentally validated.

Efficient Design of Real Time Bio-Signal Preprocessing for Wearable Devices.

Wearable devices for body-status monitoring require various signal processing such as ambient noise filtering and signal quality evaluation. While wearable devices are very limited in resource, conventional noise filtering and signal quality evaluating methods consume considerable amount of processing power. Moreover, these conventional methods are not suitable for processing bio-signals in terms of its performance.

Data mining investigation of the association between a limb ballistocardiogram and blood pressure.

Objective: To investigate the association between a limb ballistocardiogram (BCG) and blood pressure (BP) based on data mining.

Approach: During four BP-perturbing interventions, the BCG and reference BP were measured from 23 young, healthy volunteers using a custom-manufactured wristband equipped with a MEMS accelerometer and a commercial continuous BP measurement device. Both timing and amplitude features in the wrist BCG waveform were extracted, and significant features predictive of diastolic (DP) and systolic (SP) BP were selected using stepwise linear regression analysis.

Development of an anaerobic threshold (HRLT, HRVT) estimation equation using the heart rate threshold (HRT) during the treadmill incremental exercise test.

Purpose: The purpose of this study was to develop a regression model to estimate the heart rate at the lactate threshold (HRLT) and the heart rate at the ventilatory threshold (HRVT) using the heart rate threshold (HRT), and to test the validity of the regression model.

Methods: We performed a graded exercise test with a treadmill in 220 normal individuals (men: 112, women: 108) aged 20-59 years. HRT, HRLT, and HRVT were measured in all subjects.

Estimation of Thermal Sensation Based on Wrist Skin Temperatures.

Thermal comfort is an essential environmental factor related to quality of life and work effectiveness. We assessed the feasibility of wrist skin temperature monitoring for estimating subjective thermal sensation. We invented a wrist band that simultaneously monitors skin temperatures from the wrist (i.

Evaluation of Radiographic Instability of the Trapeziometacarpal Joint in Women With Carpal Tunnel Syndrome.

Purpose: To determine whether median nerve dysfunction measured by electrophysiologic studies in carpal tunnel syndrome (CTS) is associated with thumb trapeziometacarpal (TMC) joint instability.

Methods: We evaluated 71 women with CTS and 31 asymptomatic control women. Patients with generalized laxity or TMC joint osteoarthritis were excluded.

Clinical correlates of Hachinski ischemic score and vascular factors in cognitive function of elderly.

The aim of this study is to investigate the relationship between Hachinski ischemic score (HIS) and vascular factors as well as between HIS and the cognitive function in elderly community. Demographic characteristics, such as sex, age, education, history of drinking and smoking, family history of dementia and stroke, diabetes mellitus, hypertension, hyperlipidemia, cardiovascular disease, stroke, and dementia, were surveyed. Neurological examination was administered to every subject and HIS was checked by a neurologist.

Flexible capacitive electrodes for minimizing motion artifacts in ambulatory electrocardiograms.

This study proposes the use of flexible capacitive electrodes for reducing motion artifacts in a wearable electrocardiogram (ECG) device. The capacitive electrodes have conductive foam on their surface, a shield, an optimal input bias resistor, and guarding feedback. The electrodes are integrated in a chest belt, and the acquired signals are transmitted wirelessly for ambulatory heart rate monitoring.

Motion artifact reduction in electrocardiogram using adaptive filtering based on half cell potential monitoring.

The electrocardiogram (ECG) is the main measurement parameter for effectively diagnosing chronic disease and guiding cardio-fitness therapy. ECGs contaminated by noise or artifacts disrupt the normal functioning of the automatic analysis algorithm. The objective of this study is to evaluate a method of measuring the HCP variation in motion artifacts through direct monitoring.

Effect of pressurization methods on the accuracy of wrist blood pressure measurement.

In developing a wrist blood pressure monitor of high and reliable accuracy, the effect of different pressurization methods on the accuracy of blood pressure measurement at the wrist using oscillometry is investigated in this paper. 30 volunteers are recruited and blood pressure readings are taken with three different methods of pressurizing the wrist. It was found that measurement of mean arterial pressure (MAP) is more accurate when the wrist is locally compressed directly over the radial artery (-2.

Factors affecting the accuracy of volume-oscillometric blood pressure measurement during partial pressurization of the wrist.

We compared the volume-oscillometric responses of the airbag pressure sensor and the contact force sensor across and along the radial artery on the wrist during partial pressurization by an airbag. Because of the anatomic structure and non-uniform pressurization pressure distribution, elongated and shifted oscillometric pressure waveform envelope variations are observed. For the contact force sensors directly above the radial artery, S-shaped pressurization curves can be seen possibly due to temporal softening of the radial artery stiffness at near zero transmural pressure.

Clinical features and treatment outcomes of upper gastrointestinal bleeding in patients with cirrhosis.

With recent progress in treatment modalities, mortality from upper gastrointestinal (UGI) bleeding has decreased appreciably. The aim of this study was to establish how UGI bleeds are managed in Korean patients with cirrhosis and to evaluate treatment outcomes. A total of 479 episodes of acute UGI bleeding in 464 patients with cirrhosis were included during a six-month period at nine tertiary medical centers.

The preliminary study on the clinical application of the WHAM (Wearable Heart Activity Monitor).

In this paper, we investigated the validity of the WHAM (wearable heart activity monitor) in the clinical applications, which has been implemented as a wearable ambulatory device for continuously and long-term monitoring user's cardiac conditions. To this end, using the WHAM and the conventional Holter monitor the ECG signals over 24 hours were recorded during daily activities. The signal from the WHAM was compared with that from the conventional Holter monitor in terms of the readability of the signal, the quality of the signal, and the accuracy of arrhythmia detection.

[Clinical features of pseudoaneurysms complicating pancreatitis: single center experience and review of Korean literature].

Background/aims: Pseudoaneurysm is a life-threatening complication of chronic or acute pancreatitis. This study was undertaken to evaluate the clinical features of pseudoaneurysm complicating pancreatitis.

Methods: We reviewed the medical records of 7 patients diagnosed as pseudoaneurysms with chronic pancreatitis in Korea University Guro and Anam Hospital from January 1995 to March 2006 and analyzed their demographics, clinical courses and outcomes.

[A case of vasculitis in chronic hepatitis C patient treated with pegylated interferon alpha-2a and ribavirin].

There has been an increase in the number of patients treated with pegylated interferon (PEG-IFN) and ribavirin due to the better antiviral efficacy. The main serious adverse events of PEG-IFN plus ribavirin combination therapy are bone marrow suppression and hemolytic anemia. However, there are few reports of vasculitis occurring during PEG-IFN therapy.

Implementation of Measuring Bio-signals Simultaneously using Time-Sharing Method.

In this paper, we propose a measuring device implementation to measure ECG, 50KHz BIA for getting BIA/Respiration, and 10~50Hz GSR for measuring electrical characteristics of skin. To this end, BIA signal is separated by line filter and high impedance element and the interference between signals could be minimized by switching in time domain to separate ECG and GSR signals having the similar frequency range. ECG, heart rate and respiration are measured by the simulator based on the implemented circuit and BIA and GSR impedance are verified using standard resistance.

WHAM: A novel, wearable heart activity monitor based on Laplacian potential mapping.

In this paper, a novel, wearable cardiac monitor (hereafter called WHAM) is proposed which allows a continuous and real-time monitoring of user's cardiac conditions. The proposed device is composed of 3 main components: a disposable electrode, a controller, and personal gateway (e.g.

[A prospective study comparing the efficacy of early administration of terlipressin and somatostatin for the control of acute variceal bleeding in patients with cirrhosis].

Background/aims: Terlipressin and somatostatin decrease portal venous pressure and they are used for the treatment of variceal bleeding. However, only a few studies have compared the efficacy of these drugs in combination with other procedures for hemostasis. Therefore, we performed a prospective study to compare the efficacy of terlipressin and somatostatin for controlling acute variceal bleeding when used in combination with other procedures for hemostasis.

[Spontaneous resolution of vanishing bile duct syndrome in Hodgkin's lymphoma].

Cholestasis in a patient with Hodgkin's disease is uncommon, and the causes of cholestasis are mainly direct tumor involvement of the liver, hepatotoxic effects of drugs, viral hepatitis, sepsis and opportunistic infections. Vanishing bile duct syndrome (VBDS) represents a very rare cause for cholestasis in this disease. We report here on a case of a 45-year-old man who developed VBDS during the complete remission stage of Hodgkin's lymphoma.