Wireless wearable photoplethysmography sensors for continuous blood pressure monitoring

Abstract

Abstract-Blood Pressure (BP) is a crucial vital sign taken into consideration for the general assessment of patient's condition: patients with hypertension or hypotension are advised to record their BP routinely. Particularly, hypertension is emphasized by stress, diabetic neuropathy and coronary heart diseases and could lead to stroke. Therefore, routine and long-term monitoring can enable early detection of symptoms and prevent life-threatening events. The gold standard method for measuring BP is the use of a stethoscope and sphygmomanometer to detect systolic and diastolic pressures. However, only discrete measurements are taken. To enable pervasive and continuous monitoring of BP, recent methods have been proposed: pulse arrival time (PAT) or PAT difference (PATD) between different body parts are based on the combination of electrocardiogram (ECG) and photoplethysmography (PPG) sensors. Nevertheless, this technique could be quite obtrusive as in addition to at least two contacts/electrodes to measure the differential voltage across the left arm/leg/chest and the right arm/leg/chest, ECG measurements are easily corrupted by motion artefacts. Although such devices are small, wearable and relatively convenient to use, most devices are not designed for continuous BP measurements. This paper introduces a novel PPG-based pervasive sensing platform for continuous measurements of BP. Based on the principle of using PAT to estimate BP, two PPG sensors are used to measure the PATD between the earlobe and the wrist to measure BP. The device is compared with a gold standard PPG sensor and validation of the concept is conducted with a preliminary study involving 9 healthy subjects. Results show that the mean BP and PATD are correlated with a 0.3 factor. This preliminary study shows the feasibility of continuous monitoring of BP using a pair of PPG placed on the ear lobe and wrist with PATD measurements is possible.

Preliminary study for hemodynamics monitoring using a wearable device network

“…A wireless wearable PPG device has been developed [9], [10]. Using Bluetooth low energy communication, the data are remotely sent to a mobile application on a smart device.…”

“…Composed of a red (740nm) LED and a photodetector (TEMD5010X01 from Vishay), the compact device is 11x18mm 2 (see figure 1). The embedded software is similar to that previously described [9], [10]. Ethical approval was obtained from the NHS South East London Research Ethics Committee 3 in December 2010 (10/H0808/124).…”

“…The protocol consisted in: 1) 5 minutes holding in a given posture P i 2) DBP, SBP and HR measurement while in posture P i 3) 5 minutes data acquisition holding in posture P i 4) DBP, SBP and HR measurement while in posture P i 5) 2 minutes holding in posture P i 6) DBP, SBP and HR measurement while in posture P i 7) change to posture P i+1 with i, the posture ID number, i={1,2,3}; it was therefore repeated 3 times, for each posture. The data was then analysed to retrieve PAT measurements following this process [10] (see figure 2): 1) Time synchronisation: using data time stamp, the signals are synchronised with each other. 2) Data filtering: a low pass filter is applied on each acquired signal.…”

Intelligent COVID-19 Forecasting, Diagnoses and Monitoring Systems: A Survey

“…Internet of Thing (IoT) technology alongside its wearable sensor nodes and vision based technology (cameras) have effectively been utilized in monitoring and diagnosing constant illnesses, for example, patients experiencing Parkinson [35] and Alzheimer's [36] disease, monitoring of blood-glucose levels in diabetic patients [37], Respiratory rate [38], blood pressure [39] [40] [41] [42] [42] [43], and detecting cardiovascular failure [44] 1 . Based on the advantages and the suitability of IoTs in healthcare systems, we have explored several research efforts towards developing IoT based COVID-19 monitoring and diagnosis healthcare systems.…”

Opportunities and Challenges of Integrating Internet of Things (IOT) With Infrastructure of Healthcare Units

“…A significant number of works [31] [32] have attempted to obtain an accurate estimate of BP through calculation of pulse transit time (PTT) -the time taken between pulse at the heart and pulse at another location, such as the earlobe or radial artery. Another work endeavored to measure this property between the ear and wrist [33], while another looked to calculate it between the palm and the fingertip of a hand [34]. PTT is known to be inversely proportional to systolic blood pressure (SBP), and is typically determined using an electrocardiogram on the chest and a PPG sensor on the ear, wrist, or alternate location.…”