Accuracy and Consistency of Respiratory Inductive Plethysmography for Overnight Tidal Volume Measurement

To validate the accuracy and consistency of respiratory inductive plethysmography (RIP) in measuring tidal volume after an overnight sleep, tidal volumes of 18 patients with suspected sleep disordered breathing and 8 normal volunteers were measured simultaneously with RIP (V TRIP ) and with an ultrasonic airflow meter (V TUFM ) before and after an unstrained overnight sleep on supine and lateral decubitus. The bias of the V TRIP was expressed as (V TRIP V TUFM )/ V TUFM ·100 %, limits of agreement between V TRIP and V TUFM was measured by averaged bias ±2 s . Results showed that in normal subjects, the bias of RIP before and after overnight sleep was precise and consistent in both supine (0.7 % and -1.6 %) and lateral decubitus (3.7 % and -0.56 %). In these patients, the bias of RIP before and after sleep in supine also remained small (1.9 % and 1.7 %), but it became larger in lateral decubitus (24.5 % and 20.4 %) and 11.5 % exceeded the limits of agreement observed in the evening. The patients′ body mass indices (BMI) were higher than those of normal subjects (median 34.2 vs. 27.8 kg/m 2). Pooled data showed that the bias of V TRIP in the morning on lateral decubitus but not on supine was correlated to BMI (Spearman R=0.32, n =52, P =0.02). Thus, we were led to conclude that the accuracy of V TRIP overnight was precise and consistent in normal subjects, but the deviation of V TRIP measured on lateral decubitus in patients especially in those with excessive obesity was greater, thus, the method should not be used for quantitative determination.

Development of forearm impedance plethysmography for the minimally invasive monitoring of cardiac pumping function

It is essential to continuously and non-invasively monitor the cardiac pumping function in clinical setting. Thus, the study aimed to explore a regional impedance phethysmographic method to assess the changes in stroke volume. To do this, we developed a plethysmographic device that was capable of delivering a single-frequency current with constant amplitude and of recording electrical impedance signals of biological tissue. The electrical impedance plethy- smographic waveform form the lower arm was measured with the impedance plethysmographic device, and simultaneously the end-systolic and end- diastolic volumes of the left ventricle were obtained with a two-dimension echocardiographic system in fourteen healthy subjects before and immediately after a thirty-second breath-hold maneuver. For the 14 subjects, a linear correlation coefficient of 0.79 (p < 0.001) was obtained between the changes in peak amplitude of the forearm impedance waveform and the changes in stroke volume before and just after the breath-hold test. In addition, the changes in the mean area under the impedance curve and the change in stroke volume were also correlated linearly (r = 0.71, p < 0.005). In summary, the forearm impedance plethysmography may be employed to evaluate the beat-to-beat alteration in cardiac stroke volume, suggesting its potential for long-term monitoring cardiac pumping performance.

Cuffless Blood Pressure Estimation Based on Both Artificial and Data-Driven Features from Plethysmography

Blood pressure(BP)is an important indicator of individuals’health conditions for the prevention or treatment of cardiovascular disease.However,conventional measurements require inconvenient cuffbased instruments and are not able to detect continuous blood pressure.Advanced methods utilize machine learning to estimate BP by constructing artificial features in plethysmography(PPG)or using an end-to-end deep learning framework to estimate BP directly.Empirical features are limited by current research on cardiovascular disease and are not sufficient to express BP variability,while data-driven approaches neglect expert knowledge and lack interpretability.To address this issue,in this paper we propose a method for continuous BP estimation that extracts both artificial and data-driven features from PPG to take advantage of expert knowledge and deep learning at the same time.Then a deep residual neural network is designed to reduce information redundancy in the gathered features and refine high-level features for BP estimation.The results show that our proposed methods outperforms the compared methods in three commonly used metrics.

Altered heart rate variability and pulse-wave velocity after spinal cord injury

BACKGROUND Heart rate variability(HRV) and pulse-wave velocity(PWV),indicators of cardiac function,are altered in patients with spinal cord injury(SCI),suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients.No study has simultaneously investigated HRV and PWV in the same patients.AIM To evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.METHODS In this cross-sectional pilot study,patients with(n = 60) and without SCI(n = 60) were recruited from December 7,2019 to January 21,2020.Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000 P.Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.RESULTS We observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals,square root of the mean sum of squared successive risk ratio interval differences,physical stress index,total power,very-low frequency,low frequency,high frequency,and arterial elasticity.CONCLUSION Patients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without,suggesting that SCI may increase cardiac function loading.

One approach to circulation and blood flow in the critical care unit

Evaluating and managing circulatory failure is one of the most challenging tasks for medical practitioners involved in critical care medicine.Understanding the applicability of some of the basic but,at the same time,complex physiological processes occurring during a state of illness is sometimes neglected and/or presented to the practitioners as point-of-care protocols to follow.Furthermore,managing hemodynamic shock has shown us that the human body is designed to fight to sustain life and that the compensatory mechanisms within organ systems are extraordinary.In this review article,we have created a minimalistic guide to the clinical information relevant when assessing critically ill patients with failing circulation.Measures such as organ blood flow,circulating volume,and hemodynamic biomarkers of shock are described.In addition,we will describe historical scientific events that led to some of our current medical practices and its validation for clinical decision making,and we present clinical advice for patient care and medical training.

Is obesity related to the lung function of non-asthmatic children?

Overweight and obesity are highly prevalent in developed and developing countries among children and adolescents. During the last two decades, it became evident that excess weight is adversely related to respiratory health in childhood and adolescence mainly in terms of asthma occurrence. Additionally, there is a mounting body of evidence that overweight/obesity may also affect lung function in non-asthmatic subjects. The aim of this review was to present and discuss the studies that investigated this issue in non-asthmatic children and adolescents. Only a few studies have evaluated the impact of excess weight on static volumes and their results point towards an inverse relationship between overweight/obesity and functional residual capacity. More studies have been conducted on the impact of excess weight on dynamic lung volumes with inconsistent, however, results. Nevertheless, a relatively consistent finding was that the ratio of forced expiratory volume in 1 s/forced vital capacity was significantly lower among overweight/obese children compared to their counterparts with normal weight. The underlying mechanisms of these observations have not been adequately elucidated but it is believed to result from complex interaction of mechanical, developmental, and metabolic causes. There is a need for more welldesigned studies in order to clarify the impact of excess weight on lung function in non-asthmatic subjects, as well as to explore the contribution of factors such as duration and degree of obesity, and fat distribution. Despite the absence of conclusive data, there are stillconvincing evidence to be communicated to the children and their families as part of the arguments to encourage them to adopt a healthier lifestyle.

Electrical impedance tomography based image reconstruction and feto-maternal monitoring in pregnancy

Standard methods of monitoring the fetus and maternal health during labor are cardioto-cogram, tocography, ultrasound and magneto-cardiograpghy. These methods have some limi-tations in real time continuous monitoring and cause some degree of inconvenience to the pa-tient and demand special attendance of the ob-stetrician also these methods cannot be used for continuous monitoring of the fetal well being. To overcome the limitations of above techniques, a non-invasive bioimpedance measuring method is proposed. This technique helps in monitoring and recording of the electrical field distribution of a closed object. The output variation on the outer surface is likely to provide information because of fetal movements and related physio-logical parameters. It will also help in the de-velopment of Electrical Impedance Tomography based imaging technique for a closed body system with special reference to fetal monitor-ing in-utero during pregnancy and labor. Also we have developed the data acquisition system of 16 electrodes with software for image recon-struction.

Eliminating Forgers Based on Intra Trial Variability in Online Signature Verification Using Handglove and Photometric Signals

The novel reinforcement to the data glove based dynamic signature verification system, using the Photometric measurement values collected simultaneously from photo plethysmography (PPG) during the signing process is the emerging technology. Skilled forgers try to attempt the genuine signatures in many numbers of trials. The wide gap in the Euclidian distances between forgers and the genuine template features prohibits them from successful forging. This has been proved by our repeated experiments on various subjects using the above combinational features. In addition the intra trial features captured during the forge attempts also differs widely in the case of forgers and are not consistent that of a genuine signature. This is caused by the pulse characteristics and degree of bilateral hand dimensional similarity, and the degrees of pulse delay. Since this economical and simple optical-based technology is offering an improved biometric security, it is essential to look for other reinforcements such the variability factor considerations which we proved of worth considering.

Should We Measure the FEV1 or the Specific Resistance of the Airways? An Evaluation in Patients with Either COPD, Chronic Dyspnea or Chronic Cough

Background: The purpose of this study was to evaluate the relative contribution of measuring the forced expiratory volume in one second (FEV1) or the specific resistance of the airways (sRaw) in adults referred for chronic obstructive pulmonary disease (COPD), chronic dyspnea or chronic cough. Methods: This was a prospective study of 321 subjects referred for lung function testing, in a setting of routine clinical management, for suspicion of COPD (or follow-up of known COPD), chronic dyspnea or chronic cough. The proportions of FEV1 values below the normal range and of sRaw values above the normal range were compared using a Chi-square exact test of Fisher. Results: In the COPD and chronic dyspnea groups, sRaw was as frequently abnormal as FEV1. In the chronic cough group, sRaw was increased in 56.5% of subjects, while FEV1 was decreased in solely 34.8% (p = 0.059). Conclusions: This study suggests that sRaw may be a better tool than FEV1 to detect bronchial obstruction in patients presenting with chronic cough.

Non-Contact Blood Pressure Measurement Based on IPPG

Blood pressure is an important physiological parameter to reflect human vital signs.In order to achieve the non-contact dynamic blood pressure acquisition based on ordinary optical camera,a theoretical understanding of the functional relationship between blood pressure and pulse wave signal conduction time.And through imaging photoelectric plethysmography(IPPG),pulse wave signal conduction time of forehead and hand was obtained with ordinary optical camera.First,the pulse wave conduction time was obtained by recording the video with an ordinary optical camera.Second,real-time blood pressure values were collected.Finally,based on the relationship between blood pressure and pulse wave conduction time,a non-contact blood pressure measurement prediction model was obtained through neural network fitting.So that non-contact blood pressure measurement with optical camera could be completed.The method in this paper has several advantages,such as low requirements on measuring equipment,low cost,and simple operation.It can let people get rid of the discomfort caused by measuring equipment such as cuff and can measure blood pressure at any time.The predicted blood pressure results were compared with an Omron wrist electronic sphygmomanometer.The calculated error of systolic blood pressure is-9.28%~3.16%,and the error of diastolic blood pressure is-9.84~4.35%.