Reconfigurable multiband concurrent RF system for non-invasive human vital sign detection

Huge hospital information system databases can be mined for knowledge discovery and decision support, but artifact in stored non-invasive vital sign (VS) high-frequency data streams limits its use. We used machine-learning (ML) algorithms trained on expert-labeled VS data streams to automatically classify VS alerts as real or artifact, thereby "cleaning" such data for future modeling. 634 admissions to a step-down unit had recorded continuous noninvasive VS monitoring data [heart rate (HR), respiratory rate (RR), peripheral arterial oxygen saturation (SpO2) at 1/20Hz, and noninvasive oscillometric blood pressure (BP)]. Time data were across stability thresholds defined VS event epochs. Data were divided Block 1 as the ML training/cross-validation set and Block 2 the test set. Expert clinicians annotated Block 1 events as perceived real or artifact. After feature extraction, ML algorithms were trained to create and validate models automatically classifying events as real or artifact. The models were then tested on Block 2. Block 1 yielded 812 VS events, with 214 (26%) judged by experts as artifact (RR 43%, SpO2 40%, BP 15%, HR 2%). ML algorithms applied to the Block 1 training/cross-validation set (tenfold cross-validation) gave area under the curve (AUC) scores of 0.97 RR, 0.91 BP and 0.76 SpO2. Performance when applied to Block 2 test data was AUC 0.94 RR, 0.84 BP and 0.72 SpO2. ML-defined algorithms applied to archived multi-signal continuous VS monitoring data allowed accurate automated classification of VS alerts as real or artifact, and could support data mining for future model building.

Complications occur in a third of patients after major noncardiac surgery and are often preceded by vital sign deviations undetected by current vital sign monitoring practice, despite major advances in surgical and perioperative care. Continuous wireless vital sign monitoring with real-time alerts may allow for a reduction of vital sign abnormalities and complications. Adult patients undergoing major noncardiac surgery were included and randomized to either standard of care (manual intermittent vital sign monitoring) vs standard of care plus continuous wireless vital sign monitoring with real-time vital sign alerts to staff smartphones at the general postoperative ward. The primary outcome was cumulative duration of severe vital sign deviations, including desaturation, tachy- and bradycardia, tachy- and bradypnea, hypo- and hypertension. Secondary outcomes included adverse events within 30 days. Patients and outcome assessors were blinded to the randomization. Four hundred patients were randomized, with 200 in the intervention and 200 in the control group, respectively. Median [interquartile range (IQR)] duration of severely deviating vital signs was 60 [25-136] vs 76 [28-192] min/d in the intervention versus control group, respectively ( P = .19). Duration of Sp o2 <88% had a mean reduction of 47 minutes per day (95% confidence interval [CI], 18-80, P = .02). Adverse events occurred in 42.5% vs 31.5% of patients within 30 days ( P = .02), and serious adverse events in 34.5% vs 29.5% ( P = .39). Continuous vital sign monitoring with real-time staff alerts did not significantly reduce cumulative severe vital sign deviations in this setup. Significant reductions in desaturations and adverse events were found, giving evidence to future studies in the use of continuous vital sign monitoring to improve patient outcomes.

Recent developments make the continuous monitoring of vital signs outside the critical care setting feasible, and may provide a benefit in terms of improved patient outcomes and cost efficiency. A meta-aggregative systematic review was conducted to provide an overview of the experiences of nurses working with continuous monitoring of vital signs in patients admitted to a hospital general ward. All study designs describing nurses' experiences in a qualitative manner were included. Relevant studies were identified by searching the electronic databases Pubmed, Cinahl and Embase from 2017 up to September 2024. The search strategy combined 'nurses', 'continuous monitoring/measuring', 'vital signs', and 'hospital/(general) wards' as well as synonyms. Of 3066 articles found, nine were included. Four themes were synthesized: 1) Emotional and practical advantages, e.g., patients feel safer and nurses feel more secure, as continuous monitoring detects patients deterioration earlier; 2) practical disadvantages, e.g., reduced nurse-patient interaction and stress related to changing vital signs, potential over-monitoring and data overloading; 3) important aspects related to the implementation process, e.g., training and coaching, properly working technical infrastructure; and 4) alarm strategies and clinical assessment, e.g., reducing unnecessary alarms. We conclude that nurses report varying experiences in working with continuous monitoring of vital signs on the general ward. The advantages of continuous monitoring seem to justify investing in further development of the systems and sensors in order to reduce the practical disadvantages. The findings may facilitate optimal implementation of continuous monitoring of vital signs.

Photonic implementation of a highly reconfigurable wideband RF spectral shaper

Continuous and wireless vital sign (VS) monitoring on hospital wards is superior to intermittent VS monitoring at detecting VS abnormalities; however, the impact on clinical outcomes remains to be confirmed. A recent propensity-matched study of primary surgical patients found decreased odds of intensive care unit (ICU) admission and mortality in patients receiving continuous monitoring. Primary surgical patients are inherently different from their medical counterparts who typically have high morbidity, including frailty. Continuous monitoring research has been limited in primary medical patients. This study aims to evaluate the clinical outcomes of primary medical patients who received either continuous or, as a contemporaneous control, intermittent vital monitoring as the standard of care using propensity matching. Propensity-matched analysis of a population-based sample of 7971 patients admitted to the medical wards between January 2018 and December 2019 at a single, tertiary United States medical center. The continuous monitoring device measures oxygen saturation, heart rate, respiratory rate, continuous noninvasive blood pressure, and either 3-lead or 5-lead electrocardiogram. Patients received either 12 hours or more of continuous and wireless VS monitoring (n=1450) or intermittent VS monitoring (n=6521). The primary outcome was the odds of a composite of in-hospital mortality or ICU transfer during hospitalization. Secondary outcomes were the odds of individual components of the primary outcome, as well as heart failure (HF), myocardial infarction (MI), acute kidney injury (AKI), and rapid response team (RRT) activations. Those who received intermittent VS monitoring had greater odds of a composite of in-hospital mortality or ICU admission (odds ratio [OR] 2.79, 95% CI 1.89-4.25; P<.001) compared with those who had continuous and wireless VS monitoring. The odds of HF (OR 1.03, 95% CI 0.83-1.28; P=.77), MI (OR 1.58, 95% CI 0.77-3.47; P=.23), AKI (OR 0.74, 95% CI 0.62-1.02; P=.06), and RRT activation (OR 0.94, 95% CI 0.75-1.19; P=.62) were similar in both groups. In this propensity-matched study, medical ward patients who received standard of care intermittent VS monitoring were at nearly 3 times greater odds of transfer to the ICU or death compared with those who received continuous VS monitoring.Our study was primarily limited by the inability to match patients on admission diagnosis due to limitations in electronic health record data. Other limitations included the number of and reasons for false alarms, which can be challenging with continuous monitoring strategies. Given the limitations of this work, these observations need to be confirmed with prospective interventional trials.

In order to solve the problem of the null detection point in the vital signs detection based on continuous wave(CW) Doppler radar, a novel dual-band hybrid down-conversion radar transceiver system is proposed. The proposed radar system operating frequency is 2.05 GHz and 1.64 GHz. Correlation between signals can improve the overall performance of the system. At λ/4 distance, the single-band single-channel detection has the problem of null detection point, and the proposed dual-band double-channel detection can solve the null detection point. On the other hand, at the non-λ/4 distance, the results of the dual-band detection double-channel can be mutually verified, ensuring the detection accuracy of the vital sign detection system. The simulation results prove the feasibility of the radar system. Regardless of whether the detected distance is at the λ/4 distance, the proposed vital sign detection system can always obtain the vital sign.

Within an increasingly connected world, the exponential growth in the deployment of Internet of Things (IoT) applications presents a significant challenge in power and data transfer optimisation. Currently, the maximization of Radio Frequency (RF) system power gain depends on the design of efficient, commercial chips, and on the integration of these chips by using complex RF simulations to verify bespoke configurations. However, even if a standard 50Ω transmitter’s chip has an efficiency of 90%, the overall power efficiency of the RF system can be reduced by 10% if coupled with a standard antenna of 72Ω. Hence, it is necessary for scalable IoT networks to have optimal RF system design for every transceiver: for example, impedance mismatching between a transmitter’s antenna and chip leads to a significant reduction of the corresponding RF system’s overall power efficiency. This work presents a versatile design framework, based on well-known theoretical methods (i.e., transducer gain, power wave approach, transmission line theory), for the optimal design in terms of power delivered to a load of a typical RF system, which consists of an antenna, a matching network, a load (e.g., integrated circuit) and transmission lines which connect all these parts. The aim of this design framework is not only to reduce the computational effort needed for the design and prototyping of power efficient RF systems, but also to increase the accuracy of the analysis, based on the explanatory analysis within our design framework. Simulated and measured results verify the accuracy of this proposed design framework over a 0–4 GHz spectrum. Finally, a case study based on the design of an RF system for Bluetooth applications demonstrates the benefits of this RF design framework.

Validation of a radio frequency identification system for monitoring the feeding patterns of feedlot cattle

The noninvasive measurement and sensing of vital bio signs, such as respiration and cardiopulmonary parameters, has become an essential part of the evaluation of a patient’s physiological condition. The demand for new technologies that facilitate remote and noninvasive techniques for such measurements continues to grow. While previous research has made strides in the continuous monitoring of vital bio signs using lasers, this paper introduces a novel technique for remote noncontact measurements based on radio frequencies. Unlike laser-based methods, this innovative approach offers the advantage of penetrating through walls and tissues, enabling the measurement of respiration and heart rate. Our method, diverging from traditional radar systems, introduces a unique sensing concept that enables the detection of micro-movements in all directions, including those parallel to the antenna surface. The main goal of this work is to present a novel, simple, and cost-effective measurement tool capable of indicating changes in a subject’s condition. By leveraging the unique properties of radio frequencies, this technique allows for the noninvasive monitoring of vital bio signs without the need for physical contact or invasive procedures. Moreover, the ability to penetrate barriers such as walls and tissues opens new possibilities for remote monitoring in various settings, including home healthcare, hospital environments, and even search and rescue operations. In order to validate the effectiveness of this technique, a series of experiments were conducted using a prototype device. The results demonstrated the feasibility of accurately measuring respiration patterns and heart rate remotely, showcasing the potential for real-time monitoring of a patient’s physiological parameters. Furthermore, the simplicity and low-cost nature of the proposed measurement tool make it accessible to a wide range of users, including healthcare professionals, caregivers, and individuals seeking to monitor their own health.

Continuous monitoring of vital signs including heart rates, blood pressures, respiration rates and breath efforts is critical for eHealth. Current approaches are limited in accuracy, convenience and sensing capabilities. Some methods such as electrocardiogram (ECG) is difficult for long-term applications due to the requirement of direct skin contact, which is uncomfortable to wearers, restricts body motion and disrupts circadian rhythms. Meanwhile accurate measurement of the inter-heartbeat timing features is important for wellness monitoring and human emotion studies. In this paper, we introduce a new method to modulate the external and internal mechanical motion of the wearer body directly onto multiplexed radio frequency (RF) signals by near- field coherent sensing (NCS). To minimize the deployment and maintenance cost of NCS vital-sign monitoring, passive RF identification (RFID) tags can be integrated into garments at the chest and wrist areas. The unique ID of each tag helps discriminate its signal against interferences from ambient interferences and other tags. NCS utilizes both amplitude and phase of the electromagnetic field to couple the motion, which significantly increases the signal quality in comparison to methods based solely on signal strength. The tag backscattering signal is then processed with spectral equalization to amplify the high frequency components to recover not only the waveform details originally submerged in the low-frequency components but also the sharp peaks for precise heartbeat intervals with improved peak detection certainty. The derived heartbeat interval shows improved stability in comparison with synchronous ECG.

ObjectiveThis study aimed to determine the potential cost-savings for implementing continuous vital sign monitoring in a hospital’s medical-surgical units.MethodsA cost-savings analysis was designed to calculate potential cost-savings for an average-sized U.S. community hospital (153 total beds) over a 1-year time horizon. Analysis parameters were extracted from national databases and previous studies that compared outcomes for patients receiving continuous vital sign monitoring (SpO2, HR, and RR) or standard of care (intermittent vital sign measurements) in medical-surgical units based on a targeted literature review. Clinical parameters and associated costs served as analysis inputs. The analysis outputs were costs and potential cost-savings using a 50% and 100% adoption rate of continuous monitoring technologies across the medical-surgical unit.ResultsPotential annual cost-savings for in-hospital medical-surgical stays were estimated at $3,414,709 (2022 USD) and $6,829,418 for a 50% and 100% adoption rate, respectively. The cost-savings for an adoption rate of 100% equated to a ∼14% reduction in the overall annual cost of medical-surgical unit stays for an average-sized hospital. The largest contribution to potential cost-savings came from patients that avoided serious adverse events that require transfer to the intensive care unit; this resulted in annual cost-savings from reduced average length of stay between $1,756,613 and $3,513,226 (50% and 100% adoption rate, respectively). Additional cost-savings can be attained from reductions in in-hospital cardiac arrest-associated hospitalizations and decreased rapid response team activation.ConclusionsOur findings demonstrate that there is the potential for cost-savings of over $6.8 million dollars per year in an average-sized US community hospital by improving patient outcomes through implementation of continuous monitoring technologies in medical-surgical units. Continuous vital sign monitoring technologies that increase patient mobility and facilitate recovery may further contribute to cost-savings and should be considered for economic analyses. Future research is needed to explore these health-related outcomes.

Active harmonic EU cavity: Commissioning and operation with beam

ObjectiveMortality risk prediction (MRP) enhances healthcare resource allocations and end-of-life care. High prediction accuracy has been reported for MRP in intensive care units (ICUs). However, there have been fewer studies on the use of MRP in care facilities, which lack laboratory test data and continuous vital signs monitoring. Among related studies, vital signs-based therapy (VSbT), common in hospitals and care facilities, can dramatically affect vital signs, but VSbT effect has not been considered in related studies. This lack of consideration might cause lower prediction accuracy.MethodsThe purpose of this study was to explore the feasibility of using MRP in care facilities, but with sparse vital signs measurements from nurseChart, part of an open ICU database. To make clear the effect of VSbT on MRP, the authors proposed a feature-exploring algorithm for identifying the VSbT-related features and thereby identify a classifier for vital signs-based MRP. Moreover, appropriate vital signs measurement intervals were investigated using the data of continuous vital signs contained in the database as reference.ResultsThis study shows that of all the vital signs, temperature is strongly subject to VSbT effects. Moreover, with sparse vital signs data and certain personal information, the classifier with the proposed VSbT-related features could outperform those reported so far (G-mean: 0.6462 vs. 0.6307). Moreover, for each vital sign, the appropriate measurement interval was determined for care facility scenarios.ConclusionUsing sparse data from an open ICU database, this study shows the feasibility of vital sign-based MRP use at care facilities, which is a big step towards the practical use of the MRP in those facilities.

The use of the noninvasive microwave method for measuring changes in lung water content has been previously reported and validated in animal experiments. The approach is based on measuring the transmission coefficient across the thorax and correlating results with changes in lung water content. In this letter, we extend this technique to the monitoring of multiple vital signs including heart rate and breathing as well as the changes of lung water content from a single transmission coefficient measurement. Using a short-time Fourier transform-based digital signal processing method, it is shown that these vital signs can be accurately detected and extracted from a single microwave transmission coefficient measurement. Experimental measurements were made on a thorax phantom model, and the obtained data confirmed the validity and accuracy of the proposed approach. The radiation bio-safety aspects of this approach were evaluated using a DASY4 near-field scanner, often used for certifying cell phones. Obtained results for a 30-mW input power show that the specific absorption rate (SAR) values are about one third of the FCC safety standard at the operating frequency of 915 MHz. The microwave applicator design together with the experimental procedure and the extracted vital signs results are presented, and avenues for future clinical implementation are discussed.

ObjectiveTo determine feasibility, in terms of acceptability and system fidelity, of continuous vital signs monitoring in abdominal surgery patients on a general ward.DesignObservational cohort study.SettingTertiary teaching hospital.ParticipantsPostoperative abdominal surgical patients...