A Universal Noninvasive Continuous Blood Pressure Measurement System for Remote Healthcare Monitoring.

BACKGROUND: The effectiveness of any remote healthcare monitoring system depends on how much accurate, patient-friendly, versatile, and cost-effective measurement it is delivering. There has always been a huge demand for such a long-term noninvasive remote blood pressure (BP) measurement system, which could be used worldwide in the remote healthcare industry. Thus, noninvasive continuous BP measurement and remote monitoring have become an emerging area in the remote healthcare industry. INTRODUCTION: Photoplethysmography-based (PPG) BP measurement is a continuous, unobtrusive, patient-friendly, and cost-effective solution. However, BP measurements through PPG sensors are not much reliable and accurate due to some major limitations like pressure disturbance, motion artifacts, and variations in human skin tone. MATERIALS AND METHODS: A novel reflective PPG sensor has been developed to eliminate the abovementioned pressure disturbance and motion artifacts during the BP measurement. Considering the variations of the human skin tone across demography, a novel algorithm has been developed to make the BP measurement accurate and reliable. The training dataset captured 186 subjects' data and the trial dataset captured another new 102 subjects' data. RESULTS AND DISCUSSION: The overall accuracy achieved by using the proposed method is nearly 98%. Thus, demonstrating the efficacy of the proposed method. CONCLUSIONS: The developed BP monitoring system is quite accurate, reliable, cost-effective, handy, and user friendly. It is also expected that this system would be quite useful to monitor the BP of infants, elderly people, patients having wounds, burn injury, or in the intensive care unit environment.

A Literature Review on Current and Proposed Technologies of Noninvasive Blood Pressure Measurement.

BACKGROUND: Noninvasive continuous blood pressure (BP) measurement has become an evolving topic in the field of remote healthcare. The classical noninvasive BP measurement techniques provide spontaneous values of systolic and diastolic BP. On the other hand, intrusive type BP measurement techniques provide continuous values of systolic and diastolic BP. However, these techniques are very painful, cannot be used for long-term monitoring, and are obtainable only in an intensive care unit environment. With the advancement of the remote healthcare industry, there is a growing demand for noninvasive continuous BP monitoring. OBJECTIVE: The objective of this research was to present a compact literature review on the various prospective approaches of noninvasive continuous BP measurement techniques. MATERIALS & METHODS: The most contemporary and advanced technologies on noninvasive continuous BP measurement are Tactile Sensing, Vascular Unloading Technique, Pulse Transit Time, Photoplethysmography, Ultrasound-based BP measurement, BP measurement from image processing, etc. The literature search based on these technologies was conducted in EMBASE, Web of Science, IEEE, PubMed, and Ovid MEDLINE databases. In this study, each selected approach was evaluated and characterized using the following criteria: (1) accuracy; (2) cost; (3) portability; (4) comfort and convenience of use; (5) clinical health and safety; and (6) ability to integrate with the remote healthcare system. RESULTS: A detailed technical analysis was done to determine the advantages and limitations of each technique in the context of the abovementioned parameters. It was observed that BP measurement, using photoplethysmography (using camera or sensor or both), perhaps was the most promising technique among all. CONCLUSION: The study emphasized the fact that the noninvasive, continuous BP measurement technique needs to evolve further to make it reliable, accurate, and user-friendly. Lastly, a possible direction toward a more reliable and comfortable noninvasive continuous BP measurement technique has been discussed.

Flow mediated dilation with photoplethysmography as a substitute for ultrasonic imaging.

Flow mediated dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic devices prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD Index. To this end, a conventional ultrasound FMD test was carried out whereas PPG and ECG were simultaneously recorded from 20 healthy volunteers (13 M, 7 F) in the age range of 23-32 years. Our results show a significant correlation between our proposed index and ultrasound FMD when using the ECG in conjunction with the PPG (R = 0.77, p < 0.000 01). Using the PPG alone produces a lower correlation (R = 0.72, p < 0.0001). Compared to conventional FMD, the proposed method is low cost and does not require any special operator skills. Hence it may be easily utilized as a screening tool in locations deprived of high-end ultrasound imaging devices.

Use of ambient light in remote photoplethysmographic systems: comparison between a high-performance camera and a low-cost webcam.

Imaging photoplethysmography (PPG) is able to capture useful physiological data remotely from a wide range of anatomical locations. Recent imaging PPG studies have concentrated on two broad research directions involving either high-performance cameras and or webcam-based systems. However, little has been reported about the difference between these two techniques, particularly in terms of their performance under illumination with ambient light. We explore these two imaging PPG approaches through the simultaneous measurement of the cardiac pulse acquired from the face of 10 male subjects and the spectral characteristics of ambient light. Measurements are made before and after a period of cycling exercise. The physiological pulse waves extracted from both imaging PPG systems using the smoothed pseudo-Wigner-Ville distribution yield functional characteristics comparable to those acquired using gold standard contact PPG sensors. The influence of ambient light intensity on the physiological information is considered, where results reveal an independent relationship between the ambient light intensity and the normalized plethysmographic signals. This provides further support for imaging PPG as a means for practical noncontact physiological assessment with clear applications in several domains, including telemedicine and homecare.

Can photoplethysmography variability serve as an alternative approach to obtain heart rate variability information?

Heart rate variability (HRV), extracted from an electrocardiogram, is known to be a noninvasive indicator reflecting the dynamic interplay between perturbations to cardiovascular function and the dynamic response of the cardiovascular regulatory system. Photoplethysmography (PPG) is a noninvasive method to monitor arterial oxygen saturation on a continuous basis. Given the rich cardiovascular information in the PPG signal, and the ubiquity and simplicity of pulse oximetry, we are investigating the feasibility of acquiring dynamics pertaining to the autonomic nervous system from PPG waveforms. To do this, we are quantifying PPG variability (PPGV). Detailed algorithmic approaches for extracting accurate PPGV signals are presented. We compare PPGV to HRV by computing time and frequency domain parameters often associated with HRV measurements, as well as approximate entropy calculations. Our results demonstrate that the parameters of PPGV are highly correlated with the parameters of HRV. Thus, our results indicate that PPGV could be used as an alternative measurement of HRV.

[New noninvasive methods of cardiovascular system function assessment]. / Nowe nieinwazyjne metody oceny funkcji ukladu krazenia.

Increasing development of noninvasive methods of the cardiovascular system assessment as a consequence of increasing experience and technological progress cause more increasing aviability and interest of this techniques from the side of clinicians and scientists. The aim of this study was to present two noninvasive techniques: photoplethysmography and impedance cardiography with explanations of the basis of action, possibilities and limitations. Employment of this two methods opening new perspectives in haemodynamic assessment in many clinical situations for instance: shock, pulmonary edema, heart insufficiency, arterial hypertension and eclampsia. These methods could optimize farmacotherapy or stimulation parameters in patients with heart stimulation as well as to come to know and understand correlations between autonomic nervous system activity and haemodynamic changes. Noninvasivity and low costs of these procedures cause that impedance cardiography and photoplethysmographic blood pressure measurement will become wide use and acceptable methods all over the world.