Using the Bland-Altman method to measure agreement with repeated measures

Assessment of the long RR intervals using convolutional neural networks in single-lead long-term Holter electrocardiogram recordings

Advancements in medical technology have extended long-term electrocardiogram (ECG) monitoring from the traditional 24 h to 7-14 days, significantly enriching ECG data. However, this poses unprecedented challenges for physicians in analyzing these extensive datasets. While artificial neural networks have shown great potential in the automatic recognition of arrhythmias and are gradually being adopted widely, their effectiveness still requires rigorous evaluation in clinical applications. Although there have been many research on the evaluation of atrial fibrillation recognition performance, systematic evaluation of automatic detection algorithms for prolonged RR interval(RRI) remains lacking. This study aims to comprehensively evaluate these algorithms based on convolutional neural networks (CNN). We collected 480 single-lead long-term dynamic ECG records from our hospital, all from patients with prolonged RRI. Both CNN algorithms and manual analysis methods were used to analyze the ECGs, with manual analysis serving as the gold standard for performance evaluation. Results indicated that the CNN algorithm achieved an average recall rate of 98.41%, an average precision of 98.68%, and an average F1 score of 98.54%. These metrics demonstrate that CNN algorithms can meet the clinical demands for recognizing prolonged RRI, thereby enhancing physicians' confidence, especially when dealing with large volumes of RRI data. AI provides invaluable support for quantitative analysis and significantly improves diagnostic efficiency. This evaluation offers a reliable basis for deploying single-lead intelligent monitoring devices in households, communities, nursing homes, and other settings.

Validity, reliability, and measurement error of the Japanese version of the Freezing of Gait Questionnaire for patients with Parkinson's disease

BACKGROUND

The Freezing of Gait Questionnaire has been translated into several languages. However, it has not been translated into Japanese and its measurement error remains unclear.Objectives: This study aimed to translate the Freezing of Gait Questionnaire into Japanese, investigate its validity and reliability, and calculate its measurement errors.

METHODS

Thirty-five patients with Parkinson's disease participated in the study. The Freezing of Gait Questionnaire was translated into Japanese using a forward - backward translation method. Convergent validity was assessed using the Freezing of Gait Questionnaire and Unified Parkinson's Disease Rating Scale Part II(item 14-freezing). The content validity index was calculated using the Freezing of Gait Questionnaire score using correlation coefficients. Internal consistency was measured using Cronbach's alpha. The test - retest reliability was evaluated using the intraclass correlation coefficient(1,1). The Bland - Altman analysis was performed to detect the limits of agreement.

RESULTS

The mean Freezing of Gait Questionnaire score was 9.1 (5.0) points. Convergent validity was 0.655 and content validity index was 0.958. Cronbach's alpha was 0.958, intraclass correlation coefficient(1,1) was 0.951, and the limits of agreement ranged from - 4.9 to3.2 points.

CONCLUSIONS

The Japanese version of the Freezing of Gait Questionnaire is a valid and useful tool to evaluate patients with Parkinson's disease.

Validation of a novel approach to assess metabolic flexibility to a high-fat meal in a whole-body room calorimeter

OBJECTIVE

Metabolic inflexibility to Western high-fat diets may contribute to the obesity epidemic. However, validated methods for assessing metabolic flexibility (MetFlex) to high-fat meals are currently lacking. The purpose of this study was to evaluate the reliability of a novel approach for determining MetFlex to a high-fat meal and to compare it with the gold standard for measuring MetFlex to high-carbohydrate loads.

METHODS

Eight healthy adults were enrolled in our study, which consisted of the following two assessments of MetFlex: 1) MetFlex to fat, via two overnight stays in a metabolic chamber separated by 5 to 7 days; and 2) Metflex to carbohydrates, via a two-step hyperinsulinemic-euglycemic clamp measured >5 days later.

RESULTS

Participants were predominantly White and male, with mean (SD) age of 29.4 (6.3) years and BMI of 25.4 (4.1) kg/m2. MetFlex to fat displayed satisfactory test-retest reliability (intraclass correlation coefficient > 0.70) for several outcomes but showed no correlation to MetFlex measured during the clamp.

CONCLUSIONS

Overnight changes in substrate oxidation following a high-fat dinner meal represent a unique aspect of MetFlex that cannot be captured using more conventional methods. Our findings warrant prospective studies to determine whether these parameters are predictive of the development of obesity or metabolic dysfunction.

Reliability of an all-in-one wearable sensor for continuous vital signs monitoring in high-risk patients: the NIGHTINGALE clinical validation study

Continuous vital signs monitoring with wearable systems may improve early recognition of patient deterioration on hospital wards. The objective of this study was to determine whether the wearable Checkpoint Cardio's CPC12S, can accurately measure heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), blood pressure (BP) and temperature continuously. In an observational multicenter method comparison study of 70 high-risk surgical patients admitted to high-dependency wards; HR, RR, SpO2, BP and temperature were simultaneously measured with the CPC12S system and with ICU-grade monitoring systems in four European hospitals. Outcome measures were bias and 95% limits of agreement (LoA). Clinical accuracy was assessed with Clarke Error Grid analyses for HR and RR. A total of 3,212 h of vital signs data (on average 26 h per patient) were analyzed. For HR, bias (95% LoA) of the pooled analysis was 0.0 (-3.5 to 3.4), for RR 1.5 (-3.7 to 7.5) and for SpO2 0.4 (-3.1 to 4.0). The CPC12S system overestimated BP, with a bias of 8.9 and wide LoA (-23.3 to 41.2). Temperature was underestimated with a bias of -0.6 and LoA of -1.7 to 0.6. Clarke Error Grid analyses showed that adequate treatment decisions regarding changes in HR and RR would have been made in 99.2% and 92.0% of cases respectively. The CPC12S system showed high accuracy for measurements of HR. The accuracy of RR, SpO2 were slightly overestimated and core temperature underestimated, with LoA outside the predefined clinical acceptable range. The accuracy of BP was unacceptably low.

Real-world evidence for passive video-based cardiac monitoring from smartphones used by patients with a history of AF

Passive cardiac monitoring has become synonymous with wearable technologies, necessitating patients to incorporate new devices into their daily routines. While this requirement may not be a burden for many, it is a constraint for individuals with chronic diseases who already have their daily routine. In this study, we introduce an innovative technology that harnesses the front-facing camera of smartphones to capture pulsatile signals discreetly when users engage in other activities on their device. We conducted a clinical study to gather real world evidence that passive video-based cardiac monitoring is feasible and it can be used to gather daily information about cardiac status of patients with a history of atrial fibrillation (AF). The study involved 16 patients who used an application called HealthKam AFib (HK) on their Android smartphone for a period of 14 days. They also wore an ECG patch during the first 7 days that was used as a reference device. Subjects were asked to also perform self testing procedures using video selfies twice a day, but measurements were also collected in the background during normal device usage. The 16 subjects had the HK app installed on their device during an average time period of 12.8±2.3 days. On average, the measurement rate was 2.1±1.6 measurements per hour of utilization of the smartphone. Heart rate measurements were found to be highly accurate, with a mean error equal to -0.3 bpm. The study revealed that passive facial video monitoring collected reliable data in real-world conditions.

Validation of Ultrasound for Quantification of Knee Meniscal Tissue: A Cadaveric Study

Background: While MRI is the gold standard for meniscal assessment, its cost and accessibility limitations have led to growing interest in ultrasound, though its validity for quantifying meniscal tissue remains unclear. To validate the use of ultrasound in quantifying meniscal tissue across the anterior, middle, and posterior regions of both menisci (medial and lateral) in longitudinal and transverse planes by comparison with cadaveric dissection. Methods: A cross-sectional study was conducted on ten cryopreserved anatomical donors, obtaining a total of 120 ultrasound scans from the different meniscal regions. Following ultrasound imaging, cadaveric dissection was performed to facilitate photometric measurements, thereby enabling validation of the ultrasound findings. The intra-examiner reliability of the ultrasound measurements was also assessed. Results: The intra-examiner reliability of ultrasound measurements ranged from moderate to excellent. A strong and statistically significant positive correlation was observed between ultrasound and photometric measurements across all meniscal regions (r > 0.821; p < 0.05). In the medial meniscus, ultrasound visualized 99.1% of the anterior region (8.71 mm with ultrasound; 8.64 mm with photometry), 96.3% of the middle region (9.09 mm with ultrasound; 9.39 mm with photometry), and 98.5% of the posterior region (10.54 mm with ultrasound; 10.61 mm with photometry). In the lateral meniscus, ultrasound visualized 107.1% of the anterior region, 105.1% of the middle region, and 97.8% of the posterior region. The observed excess in tissue visualization in some regions likely reflects the inclusion of adjacent connective tissue, indistinguishable from meniscal tissue on ultrasound. Conclusions: Ultrasound is a valid and reliable modality for visualizing most meniscal tissue across regions, with a measurement discrepancy under 0.7 mm compared to anatomical dissection. However, caution is advised as adjacent connective tissue may sometimes be misidentified as meniscal tissue during evaluations.

Real-world smartphone-based point-of-care diagnostics in primary health care to monitor HbA1c levels in people with diabetes

BACKGROUND

The lack of accurate and affordable monitoring of glycated hemoglobin (HbA1c) is a common issue among patients with diabetes in low- and middle-income countries. We aimed to test a tablet- and smartphone-based point-of-care (TSB POC) device against a local laboratory-based measure of HbA1c for monitoring diabetes under real-world conditions.

METHODS

For this cross-sectional clinical method applicability study, capillary and venous blood was collected in duplicate and analyzed at local primary health care centers. For a heterogeneity test, the tests were performed by an expert, and by a team of local nurses. The study was conducted in a multicenter design in rural and urban Aceh, Indonesia in 2019, and included a total of 533 adults. We mainly used Bland-Altman plots to assess the number of readings within the 95%-limits of agreement (LoA) and Deming regressions.

RESULTS

The results show a mean difference between capillary HbA1c on the test device and the reference method of -0.54 [CI0.95 = -1.6933; 0.6048] with 5.21% of measurements outside the LoA and a Pearson's r = 0.91 in the Deming Regression. There is no significant difference in test concordance between local nurses and the expert (4.23% versus 5.13% results outside the LoA [CI0.95 = -0.0331; 0.0511]).

CONCLUSIONS

TSB POC for analysis of HbA1c is an acceptable alternative for accessible monitoring of diabetes patients under these conditions. This method could provide access to high-quality diagnostic decisions through regular and cost-effective HbA1c monitoring directly in healthcare facilities, thus providing better access to essential health services.

Performance of Hemochron ACT-LR and ACT+ Test Cuvettes in Monitoring Low to Moderate Heparin Concentrations: An In Vitro Study

OBJECTIVES

According to the manufacturer, the Hemochron ACT-LR cuvette is designated for heparin concentrations of 0 to 2.5 IU/mL, while the optimal concentration range for the ACT+ cartridge is 1 to 6 IU/mL. We hypothesized that at low to moderate heparin concentrations, the ACT-LR is more reliable than the ACT+.

DESIGN

An in vitro study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Twenty healthy adult volunteers.

INTERVENTIONS

Donor blood samples were spiked with unfractionated heparin to concentrations of 0, 0.5, 1.0, 1.5, 2.0, and 2.5 IU/mL. From each concentration, 3 measurements were made with each test cassette using 3 different Hemochron Signature Elite devices, for a total of 720 ACT tests. The Bland-Altman method and intraclass correlation coefficients were used to analyze the data.

MEASUREMENTS AND MAIN RESULTS

All 360 ACT+ tests yielded a result. Of 360, 38 (11%) ACT-LR tests ran above the upper measurement range; of these, 36 were from the 120 measurements at heparin concentrations ≥2.0 IU/mL. The bias between all ACT-LR and ACT+ measurements ​​was 52 (95% CI, 48-56) celite seconds, and the limits of agreement were wide. Based on the intraclass correlation coefficients, the reliability of ACT+ was better than or equal to that of ACT-LR.

CONCLUSIONS

The performance of ACT+ is equal to that of ACT-LR up to a concentration of 0.5 IU/mL, above which ACT+ is superior to ACT-LR, questioning the rationale for a specific low-range test. However, there is a significant bias between ACT-LR and ACT+ measurements that needs to be considered if switching from one test to the other.

Agreement of zero-heat-flux thermometry compared with infrared tympanic temperature monitoring in adults undergoing major surgery

The patient's body temperature significantly fluctuates, affected by factors, including anesthesia. The ideal temperature monitoring method that is suitable for perioperative application is of great significance for identifying hypothermia and malignant hyperthermia early, as well as for guiding intraoperative temperature protection. This study aims to compare the cutaneous zero-heat-flux (ZHF) thermometer application in general anesthesia using the infrared tympanic measurement as a reference. We conducted a prospective observational study and enrolled 130 patients scheduled for major surgery with general anesthesia. A forehead ZHF sensor (Tzhf) and an infrared tympanic thermometer (Ttym) were used to continuously measure core temperature. We assessed the agreement using Bland-Altman analysis and concordance correlation coefficient, comparing the paired measurement of Tzhf and Ttym. We further calculated the percentage of difference within 0.5 ℃ between the two devices. Sensitivity, specificity, and predictive values were estimated to interpret the performance of the ZHF thermometer in detecting hypothermia and hyperthermia. The analysis involved 1626 pairs of measurements for the comparison. The mean difference between the ZHF and the tympanic measurements was 0.11 ℃ ± 0.27 ℃, 93.5% of the measurements differences fell within ± 0.5 ℃. Tzhf was significantly correlated with Ttym (r = 0.90). The ZHF thermometry detected the presence of Ttym hypothermia with sensitivity and specificity of 0.89 and 0.88, respectively. Temperature monitoring with the ZHF thermometer indicates a good agreement with the infrared tympanic measurement and a high performance for detecting intraoperative hypothermia.

Multi-Planar Cervical Motion Dataset: IMU Measurements and Goniometer

This data descriptor presents a comprehensive and replicable dataset and method for calculating the cervical range of motion (CROM) utilizing quaternion-based orientation analysis from Delsys inertial measurement unit (IMU) sensors. This study was conducted with 14 participants and analyzed 504 cervical movements in the Sagittal, Frontal and Horizontal planes. Validated against a Universal Goniometer and tested for reliability and reproducibility. Analysis showed strong validity in the sagittal plane (R = 0.828 ± 0.051) and moderate in the frontal (R = 0.573 ± 0.138), with limitations in the horizontal plane (R = 0.353 ± 0.122). Reliability was high across all planes (Sagittal: ICC = 0.855 ± 0.065, Frontal: ICC = 0.855 ± 0.015, Horizontal: ICC = 0.945 ± 0.005). Our model for CROM measurements is a valuable tool aiding diagnosis, treatment planning, and monitoring of cervical spine conditions. This study presents an accessible analysis process for biomechanical assessments in cervical and spinal fields. The dataset herein serves as a benchmark for state-of-the-art machine learning models predicting head/neck position, analyzing smoothness of movements, measuring standard motion patterns, and calibrating drift based on movement comparisons.

The concurrent validity of a portable ultrasound probe for muscle thickness measurements

Ultrasound imaging is extensively used by both practitioners and researchers in assessing muscle thickness (MT); however, its use in the field is constrained by the transportability of stationary devices. New portable ultrasound probes pose as a cost-effective and transportable alternative for field-based assessments. This study evaluated the concurrent validity of a portable probe (Lumify) against a laboratory-based device (Vivid S5) in measuring MT. Eighteen participants (nine males and nine females) visited the laboratory and their MT measurements were collected using each device at five different sites (anterior and posterior arm, anterior and posterior thigh, and posterior lower leg). Bland-Altman plots (systematic and proportional bias, random error, and 95% limits of agreement), Pearson's product-moment correlation coefficient (r), and paired samples t-tests with Cohen's d effect sizes (ES) were used to assess the concurrent validity of the Lumify device. Systematic bias was low at all sites ( ≤ 0.11 cm) while proportional bias was detected only at the posterior lower leg (r2 = 0.217 [r = 0.466]). The difference in MT between devices was significant only at the anterior thigh (p < 0.05); however, ES for all sites were considered trivial (ES ≤ 0.131). Linear associations were found between the devices at each site of measurement (r ≥ 0.95). These results highlight that the Lumify probe can be used interchangeably with the Vivid S5 for MT measurements, providing practitioners and researchers with a more cost-effective and portable alternative for field-based assessments.

Comparison of the Watson formula and bioimpedance spectroscopy for measuring body volume and calculating kt/V in patients with peritoneal dialysis

CONCLUSION

There were significant differences between Vwat and Vbis and between Kt/Vwat and Kt/Vbis. Kt/Vwat may underestimate small-solute dialysis adequacy in most cases. Kt/Vbis instead of Kt/Vwat could be accounted for in creating individualized dialysis prescriptions if the patient has no obvious clinical symptoms.

Determining cold strain in cold air: a comparison of two methods of partitional calorimetry to calculate heat storage and debt in cold air with mild hypothermia

We compared two methods of partitional calorimetry to calculate heat storage and heat debt during cold air (0°C) exposure causing mild core cooling. Twelve participants performed a 5 min baseline in thermoneutral conditions (∼22.0°C, ∼50% relative humidity) followed by cold air exposure (∼0°C) until rectal temperature was reduced by ∆-0.5°C. Partitional calorimetry was used to calculate avenues of heat exchange (radiative, convective, and evaporative), heat storage, and heat debt continuously throughout cold exposure. We compared deriving these variables using prediction equations based on environmental and participant characteristics (PCALEquation Method) versus using measurement tools such as humidity sensors and heat flux discs (PCALHeat Flux Method). There were significant differences between methods (all p ≤ 0.001) for determining heat exchange, heat storage, and heat debt. At ∆-0.5°C, PCALHeat Flux Method had greater levels of radiative and convective heat exchange (PCALHeat Flux Method: -143.0 ± 16.8 W∙m2 vs PCALEquation Method: -123.0 ± 12.9 W∙m2, p ≤ 0.001), evaporative heat exchange (PCALHeat Flux Method: -9.0 ± 1.7 W∙m2 vs PCALEquation Method: -4.1 ± 0.0 W∙m2, p ≤ 0.001), heat storage (PCALHeat Flux Method: -15.0 ± 31.0 W∙m2 vs PCALEquation Method: +6.0 ± 25.9 W∙m2, p = 0.020), and heat debt (PCALHeat Flux Method: -692.0 ± 315.0 kJ vs PCALEquation Method: -422.0 ± 136.0 kJ, p ≤ 0.001). Overall, this study found the largest discrepancies between the two methods were when the environmental conditions and skin temperature were in high flux, as well as when core temperature was reduced by ∆-0.5°C. The use of PCALHeat Flux Method may be more advantageous to use in the cold to provide a higher resolution measurement of cold strain.

Using the Indonesian Computer-Based Game Prototype as a Computer-Based Game Inventory for Executive Function in Children and Adolescents: A Confirmatory Factor Analysis and Concurrent Validity Study

Executive function influences children's learning abilities and organizes their cognitive processes, behaviors, and emotions. This cross-sectional study examined whether an Indonesian Computer-Based Game (ICbG) prototype could be used as a Computer-Based Game Inventory for Executive Function (CGIEF) in children and adolescents. The study was conducted with 200 children, adolescents, and their parents. The parents completed the Behavior Rating Inventory of Executive Functioning (BRIEF) questionnaire, and the children and adolescents completed the CGIEF. Confirmatory factor analysis (CFA) and structural equation modeling (SEM) were performed using LISREL Version 8.80. The construct of CGIEF was valid/fit with normal theory-weighted least squares = 15.75 (p > .05). SEM analysis showed that the theoretical construct of the CGIEF was a valid predictor of executive function. The critical t value of the pathway was 2.45, and normal theory-weighted least squares was 5.74 (p > .05). The construct reliability (CR) for CGIEF was 0.91. Concurrent validity was assessed using the Bland-Altman plot, and the coefficient of repeatability (bias/mean) was nearly zero between the t scores of total executive functions of the CGIEF and BRIEF. This preliminary study showed that the CGIEF can be useful as a screening tool for executive dysfunction, metacognitive deficits, and behavioral regulation problems among children and adolescents in clinical samples.

Comparison of marker-less and marker-based motion capture for baseball pitching kinematics

The purpose of this study was to compare baseball pitching kinematics measured with marker-less and marker-based motion capture. Two hundred and seventy-five fastball pitches were captured at 240 Hz simultaneously with a 9-camera marker-less system and a 12-camera marker system. The pitches were thrown by 30 baseball pitchers (age 17.1 ± 3.1 years). Data for each trial were time-synchronised between the two systems using the instant of ball release. Coefficients of Multiple Correlations (CMC) were computed to assess the similarity of waveforms between the two systems. Discrete measurements at foot contact, during arm cocking, and at ball release were compared between the systems using Bland-Altman plots and descriptive statistics. CMC values for the five time series analysed ranged from 0.88 to 0.97, indicating consistency in movement patterns between systems. Biases for discrete measurements ranged in magnitude from 0 to 16 degrees. Standard deviations of the differences between systems ranged from 0 to 14 degrees, while intraclass correlations ranged from 0.64 to 0.92. Thus, the marker-based and marker-less motion capture systems produced similar patterns for baseball pitching kinematics. However, based on the variations between the systems, it is recommended that a database of normative ranges be established for each system.

A prototype photoplethysmography-based cuffless device shows promising results in tracking changes in blood pressure

Introduction

Non-invasive cuffless blood pressure devices have shown promising results in accurately estimating blood pressure when comparing measurements at rest. However, none of commercially available or prototype cuffless devices have yet been validated according to the appropriate standards. The aim of the present study was to bridge this gap and evaluate the ability of a prototype cuffless device, developed by Aidee Health AS, to track changes in blood pressure compared to a non-invasive, continuous blood pressure monitor (Human NIBP or Nexfin) in a laboratory set up. The performance was evaluated according to the metrics and statistical methodology described in the ISO 81060-3:2022 standard. However, the present study is not a validation study and thus the study was not conducted according to the ISO 81060-3:2022 protocol, e.g., non-invasive reference and distribution of age not fulfilled.

Method

Data were sampled continuously, beat-to-beat, from both the cuffless and the reference device. The cuffless device was calibrated once using the reference BP measurement. Three different techniques (isometric exercise, mental stress, and cold pressor test) were used to induce blood pressure changes in 38 healthy adults.

Results

The mean difference (standard deviation) was 0.3 (8.7) mmHg for systolic blood pressure, 0.04 (6.6) mmHg for diastolic blood pressure, and 0.8 (7.9) mmHg for mean arterial pressure, meeting the Accuracy requirement of ISO 81060-3:2022 (≤6.0 (10.0) mmHg). The corresponding results for the Stability criteria were 1.9 (9.2) mmHg, 2.9 (8.1) mmHg and 2.5 (9.5) mmHg. The acceptance criteria for the Change requirement were achieved for the 85th percentile of ≤50% error for diastolic blood pressure and mean arterial pressure but were higher than the limit for systolic blood pressure (56% vs. ≤50%) and for all parameters for the 50th percentile (32%-39% vs. ≤25%).

Conclusions

The present study demonstrated that the cuffless device could track blood pressure changes in healthy adults across different activities and showed promising results in achieving the acceptance criteria from ISO 81060-3:2022.

Agreement between three noninvasive temperature monitoring devices during spinal anaesthesia for caesarean delivery: a prospective observational study

Hypothermia during obstetric spinal anaesthesia is a common and important problem, yet temperature monitoring is often not performed due to the lack of a suitable, cost-effective monitor. This study aimed to compare a noninvasive core temperature monitor with two readily available peripheral temperature monitors during obstetric spinal anaesthesia. We undertook a prospective observational study including elective and emergency caesarean deliveries, to determine the agreement between affordable reusable surface temperature monitors (Welch Allyn SureTemp® Plus oral thermometer and the Braun 3-in-1 No Touch infrared thermometer) and the Dräger T-core© (using dual-sensor heat flux technology), in detecting thermoregulatory changes during obstetric spinal anaesthesia. Predetermined clinically relevant limits of agreement (LOA) were set at ± 0.5 °C. We included 166 patients in our analysis. Hypothermia (heat flux temperature < 36 °C) occurred in 67% (95% CI 49 to 78%). There was poor agreement between devices. In the Bland-Altman analysis, LOA for the heat flux monitor vs. oral thermometer were 1.8 °C (CI 1.7 to 2.0 °C; bias 0.5 °C), for heat flux monitor vs. infrared thermometer LOA were 2.3 °C (CI 2.1 to 2.4 °C; bias 0.4 °C) and for infrared vs. oral thermometer, LOA were 2.0 °C (CI 1.9 to 2.2 °C; bias 0.1 °C). Error grid analysis highlighted a large amount of clinical disagreement between methods. While monitoring of core temperature during obstetric spinal anaesthesia is clinically important, agreement between monitors was below clinically acceptable limits. Future research with gold-standard temperature monitors and exploration of causes of sensor divergence is needed.

Comparative analysis of different methods for protein quantification in donated human milk

Background

Human milk is the best option for feeding newborns, especially premature infants. In the absence of breast milk, milk from a human milk bank can be a suitable alternative. However, the nutritional content of human milk may be insufficient to meet these high requirements and milk fortification is needed. To facilitate the implementation of simpler and faster analyzers in neonatal healthcare facilities, this study focuses on the concordance analysis of two different analyzers, one based on mid-infrared and the other on ultrasound, in comparison to the Bradford method for determining protein concentration in human milk.

Methods

Mature milk samples from donor mothers were collected and pasteurized at the Human Milk Bank of Barcelona and protein quantification was performed using mid-infrared (MIRIS-HMA), ultrasound (MilkoScope Julie27), and the classical Bradford reference methods. The intraclass correlation coefficient (ICC) with 95% confidence interval and Bland-Altman plots were used to assess the agreement between methods.

Results

The mean protein concentration of 142 milk samples calculated using MIRIS-HMA, MilkoScope, and the Bradford assay were 1.38, 1.15, and 1.19 g/100 ml, respectively. The ICC was 0.70 for MIRIS-HMA vs. Bradford and 0.37 for MilkoScope vs. Bradford.

Conclusion

MIRIS-HMA obtained a better agreement with the Bradford technique and is a promising method for developing new devices based on MIR transmission spectroscopy principles. This study confirms how MIRIS-HMA can be used to accurately calculate the protein concentration of human milk.

Validity and Reliability of the Japanese Version of the Frontal Assessment Battery in Patients with Stroke

BACKGROUND

The Frontal Assessment Battery (FAB), which is used to assess executive function, has been translated into several languages and shown to be valid and reliable. However, the validity and reliability of the Japanese version in patients with stroke are unknown. This study aimed to investigate the validity and reliability of the Japanese version of the FAB in patients with stroke.

METHODS

The Japanese version of the FAB for dementia was modified and evaluated in 52 patients with stroke. FAB measurements were obtained twice over a 10-day period. Convergent validity was assessed using the Stroop Color Word Test (SCWT) and the Trail Making Test (TMT) part B. Internal consistency was measured using Cronbach's alpha (Cα). Test-retest evaluations were performed using intraclass correlation coefficient [ICC (2.1)] measurements, and limits of agreement (LOA) were calculated using the total FAB score.

RESULTS

The mean total FAB score was 13.4 ± 2.8 points, the ICC (2.1) was 0.856, and Cα was 0.92. The total FAB score was correlated with SCWT scores for parts I through IV (r = 0.70 to 0.77) and the TMT score for part B (ρ = -0.53). The LOA were -1.7 to 2.9 points.

CONCLUSIONS

The Japanese version of the FAB had higher validity and reliability in patients with stroke.

Feasibility and Accuracy of Wrist-Worn Sensors for Perioperative Monitoring During and After Major Abdominal Surgery: An Observational Study

INTRODUCTION

Continuous, ambulatory perioperative monitoring using wearable devices has shown promise for earlier detection of physiological deterioration and postoperative complications, preventing 'failure-to-rescue'. This study aimed to compare the accuracy of vital signs measured by wrist-based wearables with gold standard measurements from vital signs monitors or nurse assessments in major abdominal surgery.

METHODS

Adult patients were eligible for inclusion in this prospective observational study validating the Empatica E4 wrist sensor intraoperatively and postoperatively. The primary outcomes were the 95% limits of agreement (LoA) between manual and device recordings of heart rate (HR) and temperature evaluated via Bland-Altman analysis. Secondary analysis was conducted using Clarke-Error grid analysis.

RESULTS

Overall, 31 patients were recruited, and 27 patients completed the study. The median duration of recording per patient was 70.3 h, and a total of 2112 h of data recording were completed. Wrist-based HR measurement was accurate and moderately precise (bias: 0.3 bpm; 95% LoA -15.5 to 17.1), but temperature measurement was neither accurate nor precise (bias -2.2°C; 95% LoA -6.0 to 1.6). On Clarke-Error grid analysis, 74.5% and 29.6% of HR and temperature measurements, respectively, fell within the acceptable range of reference standards.

CONCLUSIONS

Continuous perioperative monitoring of HR and temperature after major abdominal surgery using wrist-based sensors is feasible but was limited in this study by low precision. While wrist-based devices offer promise for the continuous monitoring of high-risk surgical patients, current technology is inadequate. Ongoing device hardware and software innovation with robust validation is required before such technologies can be routinely adopted in clinical practice.

A validation study demonstrating portable motion capture cameras accurately characterize gait metrics when compared to a pressure-sensitive walkway

Digital quantification of gait can be used to measure aging- and disease-related decline in mobility. Gait performance also predicts prognosis, disease progression, and response to therapies. Most gait analysis systems require large amounts of space, resources, and expertise to implement and are not widely accessible. Thus, there is a need for a portable system that accurately characterizes gait. Here, depth video from two portable cameras accurately reconstructed gait metrics comparable to those reported by a pressure-sensitive walkway. 392 research participants walked across a four-meter pressure-sensitive walkway while depth video was recorded. Gait speed, cadence, and step and stride durations and lengths strongly correlated (r > 0.9) between modalities, with root-mean-squared-errors (RMSE) of 0.04 m/s, 2.3 steps/min, 0.03 s, and 0.05-0.08 m for speed, cadence, step/stride duration, and step/stride length, respectively. Step, stance, and double support durations (gait cycle percentage) significantly correlated (r > 0.6) between modalities, with 5% RMSE for step and stance and 10% RMSE for double support. In an exploratory analysis, gait speed from both modalities significantly related to healthy, mild, moderate, or severe categorizations of Charleson Comorbidity Indices (ANOVA, Tukey's HSD, p < 0.0125). These findings demonstrate the viability of using depth video to expand access to quantitative gait assessments.

Carbohydrate Estimation Accuracy of Two Commercially Available Smartphone Applications vs Estimation by Individuals With Type 1 Diabetes: A Comparative Study

BACKGROUND

Despite remarkable progress in diabetes technology, most systems still require estimating meal carbohydrate (CHO) content for meal-time insulin delivery. Emerging smartphone applications may obviate this need, but performance data in relation to patient estimates remain scarce.

OBJECTIVE

The objective is to assess the accuracy of two commercial CHO estimation applications, SNAQ and Calorie Mama, and compare their performance with the estimation accuracy of people with type 1 diabetes (T1D).

METHODS

Carbohydrate estimates of 53 individuals with T1D (aged ≥16 years) were compared with those of SNAQ (food recognition + quantification) and Calorie Mama (food recognition + adjustable standard portion size). Twenty-six cooked meals were prepared at the hospital kitchen. Each participant estimated the CHO content of two meals in three different sizes without assistance. Participants then used SNAQ for CHO quantification in one meal and Calorie Mama for the other (all three sizes). Accuracy was the estimate's deviation from ground-truth CHO content (weight multiplied by nutritional facts from recipe database). Furthermore, the applications were rated using the Mars-G questionnaire.

RESULTS

Participants' mean ± standard deviation (SD) absolute error was 21 ± 21.5 g (71 ± 72.7%). Calorie Mama had a mean absolute error of 24 ± 36.5 g (81.2 ± 123.4%). With a mean absolute error of 13.1 ± 11.3 g (44.3 ± 38.2%), SNAQ outperformed the estimation accuracy of patients and Calorie Mama (both P > .05). Error consistency (quantified by the within-participant SD) did not significantly differ between the methods.

CONCLUSIONS

SNAQ may provide effective CHO estimation support for people with T1D, particularly those with large or inconsistent CHO estimation errors. Its impact on glucose control remains to be evaluated.

Perioperative estimations of oxygen consumption from LiDCO™plus-derived cardiac output and Ca-cvO2 difference: Relationship with measurements by indirect calorimetry in elderly patients undergoing major abdominal surgery

BACKGROUND

Feasible estimations of perioperative changes in oxygen consumption (VO2) could enable larger studies of its role in postoperative outcomes. Current methods, either by reverse Fick calculations using pulmonary artery catheterisation or metabolic by breathing gas analysis, are often deemed too invasive or technically requiring. In addition, reverse Fick calculations report generally lower values of oxygen consumption.

METHODS

We investigated the relationship between perioperative estimations of VO2 (EVO2), from LiDCO™plus-derived (LiDCO Ltd, Cambridge, UK) cardiac output and arterial-central venous oxygen content difference (Ca-cvO2), with indirect calorimetry (GVO2) by QuarkRMR (COSMED srl. Italy), using data collected 2017-2018 during a prospective observational study on perioperative oxygen transport in 20 patients >65 years during epidural and general anaesthesia for open pancreatic or liver resection surgery. Eighty-five simultaneous intra- and postoperative measurements at different perioperative stages were analysed for prediction, parallelity and by traditional agreement assessment.

RESULTS

Unadjusted bias between GVO2 and EVO2 indexed for body surface area was 26 (95% CI 20 to 32) with limits of agreement (1.96SD) of -32 to 85 ml min-1m-2. Correlation adjusted for the bias was moderate, intraclass coefficient(A,1) 0.51(95% CI 0.34 to 0.65) [F (84,84) = 3.07, P<0.001]. There was an overall association between GVO2 and EVO2, in a random coefficient model [GVO2 = 73(95% CI 62 to 83) + 0.45(95% CI 0.29 to 0.61) EVO2 ml min-1m-2, P<0.0001]. GVO2 and EVO2 changed in parallel intra- and postoperatively when normalised to their respective overall means.

CONCLUSION

Based on this data, estimations from LiDCO™plus-derived cardiac output and Ca-cvO2 are not reliable as a surrogate for perioperative VO2. Results were in line with previous studies comparing Fick-based and metabolic measurements but limited by variability of data and possible underpowering. The parallelity at different perioperative stages and the prediction model can provide useful guidance and methodological tools for future studies on similar methods in larger samples.

Day-to-day reliability of basal heart rate and short-term and ultra short-term heart rate variability assessment by the Equivital eq02+ LifeMonitor in US Army soldiers

INTRODUCTION

The present study determined the (1) day-to-day reliability of basal heart rate (HR) and HR variability (HRV) measured by the Equivital eq02+ LifeMonitor and (2) agreement of ultra short-term HRV compared with short-term HRV.

METHODS

Twenty-three active-duty US Army Soldiers (5 females, 18 males) completed two experimental visits separated by >48 hours with restrictions consistent with basal monitoring (eg, exercise, dietary), with measurements after supine rest at minutes 20-21 (ultra short-term) and minutes 20-25 (short-term). HRV was assessed as the SD of R-R intervals (SDNN) and the square root of the mean squared differences between consecutive R-R intervals (RMSSD).

RESULTS

The day-to-day reliability (intraclass correlation coefficient (ICC)) using linear-mixed model approach was good for HR (0.849, 95% CI: 0.689 to 0.933) and RMSSD (ICC: 0.823, 95% CI: 0.623 to 0.920). SDNN had moderate day-to-day reliability with greater variation (ICC: 0.689, 95% CI: 0.428 to 0.858). The reliability of RMSSD was slightly improved when considering the effect of respiration (ICC: 0.821, 95% CI: 0.672 to 0.944). There was no bias for HR measured for 1 min versus 5 min (p=0.511). For 1 min measurements versus 5 min, there was a very modest mean bias of -4 ms for SDNN and -1 ms for RMSSD (p≤0.023).

CONCLUSION

When preceded by a 20 min stabilisation period using restrictions consistent with basal monitoring and measuring respiration, military personnel can rely on the eq02+ for basal HR and RMSSD monitoring but should be more cautious using SDNN. These data also support using ultra short-term measurements when following these procedures.

How well global dietary intake estimates agree: a case of sodium consumption

Global dietary data repositories are key components of nutrition surveillance. The two most comprehensive databases, the Global Dietary Database (GDD) and the Global Burden Disease (GBD), provide national dietary intake estimates but use different data sources and models to generate estimates. To explore the agreement between GDD and GBD estimates, we compared country-specific average daily sodium intakes in 169 countries over a 28-year period using descriptive statistics, the Bland-Altman method, and prevalence exceeding the intake reference level of 2.3 g/day. We detected a staggering 36% difference between GDD and GBD estimates of global mean intakes (2.68 ± 0.74 vs. 3.88 ± 1.15 g/day, respectively; p < 0.0001). As 104 (61.5%) countries reported to have over-consumed sodium by both databases, the development of standardized approaches for national dietary intake estimation is critical for monitoring global sodium intake in a systematic and comprehensive way and for implementing global strategies to reduce sodium intake.

Noninvasive hemoglobin monitoring for maintaining hemoglobin concentration within the target range during major noncardiac surgery: A randomized controlled trial

STUDY OBJECTIVE

The effect of noninvasive CO-oximetry hemoglobin (SpHb) monitoring on the clinical outcomes of patients undergoing surgery remains unclear. This trial aimed to evaluate whether SpHb monitoring helps maintain hemoglobin levels within a predefined target range during major noncardiac surgeries with a potential risk of intraoperative hemorrhage.

DESIGN

A single-center, prospective, randomized controlled trial.

SETTING

University hospital.

PATIENTS

One hundred and thirty patients undergoing elective noncardiac surgery with a potential risk of hemorrhage.

INTERVENTIONS

Patients were randomly allocated to undergo either SpHb-guided management (SpHb group) or usual care (control group).

MEASUREMENTS

The primary outcome was the rate of deviation of the total hemoglobin concentration (determined from laboratory testing) from a pre-specified target range (8-14 g/dL). This was defined as the number of laboratory tests revealing such deviations divided by the total number of laboratory tests performed during the surgery.

MAIN RESULTS

The primary outcome occurred significantly less frequently in the SpHb group as compared to that in the control group (15/555 [2.7%]) vs. 68/598 [11.4%]; relative risk, 0.24; 95% confidence interval, 0.13-0.41; P < 0.001). Fewer point-of-care blood tests were performed in the SpHb group than in the control group (median [interquartile range], 2 [1-4] vs. 4 [2-5]; P < 0.001). There were no significant intergroup differences in the number of patients who received red blood cell transfusions during surgery (SpHb vs. control, 33.8% vs. 46.2%; P = 0.201). The incidence of unnecessary red blood cell preparation (>2 units) was lower in the SpHb group than in the control group (3.1% vs. 16.9%; P = 0.024).

CONCLUSIONS

Compared with routine care, SpHb-guided management resulted in significantly lower rates of hemoglobin deviation outside the target range intraoperatively in patients undergoing major noncardiac surgeries with a potential risk of hemorrhage.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT03816514).

Augmenting authenticity for non-invasive in vivo detection of random blood glucose with photoacoustic spectroscopy using Kernel-based ridge regression

Photoacoustic Spectroscopy (PAS) is a potential method for the noninvasive detection of blood glucose. However random blood glucose testing can help to diagnose diabetes at an early stage and is crucial for managing and preventing complications with diabetes. In order to improve the diagnosis, control, and treatment of Diabetes Mellitus, an appropriate approach of noninvasive random blood glucose is required for glucose monitoring. A polynomial kernel-based ridge regression is proposed in this paper to detect random blood glucose accurately using PAS. Additionally, we explored the impact of the biological parameter BMI on the regulation of blood glucose, as it serves as the primary source of energy for the body's cells. The kernel function plays a pivotal role in kernel ridge regression as it enables the algorithm to capture intricate non-linear associations between input and output variables. Using a Pulsed Laser source with a wavelength of 905 nm, a noninvasive portable device has been developed to collect the Photoacoustic (PA) signal from a finger. A collection of 105 individual random blood glucose samples was obtained and their accuracy was assessed using three metrics: Root Mean Square Error (RMSE), Mean Absolute Difference (MAD), and Mean Absolute Relative Difference (MARD). The respective values for these metrics were found to be 10.94 (mg/dl), 10.15 (mg/dl), and 8.86%. The performance of the readings was evaluated through Clarke Error Grid Analysis and Bland Altman Plot, demonstrating that the obtained readings outperformed the previously reported state-of-the-art approaches. To conclude the proposed IoT-based PAS random blood glucose monitoring system using kernel-based ridge regression is reported for the first time with more accuracy.

Minimal detectable change of gait and balance measures in older neurological patients: estimating the standard error of the measurement from before-after rehabilitation data thanks to the linear mixed-effects models

BACKGROUND

Tracking gait and balance impairment in time is paramount in the care of older neurological patients. The Minimal Detectable Change (MDC), built upon the Standard Error of the Measurement (SEM), is the smallest modification of a measure exceeding the measurement error. Here, a novel method based on linear mixed-effects models (LMMs) is applied to estimate the standard error of the measurement from data collected before and after rehabilitation and calculate the MDC of gait and balance measures.

METHODS

One hundred nine older adults with a gait impairment due to neurological disease (66 stroke patients) completed two assessment sessions before and after inpatient rehabilitation. In each session, two trials of the 10-meter walking test and the Timed Up and Go (TUG) test, instrumented with inertial sensors, have been collected. The 95% MDC was calculated for the gait speed, TUG test duration (TTD) and other measures from the TUG test, including the angular velocity peak (ωpeak) in the TUG test's turning phase. Random intercepts and slopes LMMs with sessions as fixed effects were used to estimate SEM. LMMs assumptions (residuals normality and homoscedasticity) were checked, and the predictor variable ln-transformed if needed.

RESULTS

The MDC of gait speed was 0.13 m/s. The TTD MDC, ln-transformed and then expressed as a percentage of the baseline value to meet LMMs' assumptions, was 15%, i.e. TTD should be < 85% of the baseline value to conclude the patient's improvement. ωpeak MDC, also ln-transformed and expressed as the baseline percentage change, was 25%.

CONCLUSIONS

LMMs allowed calculating the MDC of gait and balance measures even if the test-retest steady-state assumption did not hold. The MDC of gait speed, TTD and ωpeak from the TUG test with an inertial sensor have been provided. These indices allow monitoring of the gait and balance impairment, which is central for patients with an increased falling risk, such as neurological old persons.

TRIAL REGISTRATION

NA.

Heart Rate Variability and Pulse Rate Variability: Do Anatomical Location and Sampling Rate Matter?

Wearable technology and neuroimaging equipment using photoplethysmography (PPG) have become increasingly popularized in recent years. Several investigations deriving pulse rate variability (PRV) from PPG have demonstrated that a slight bias exists compared to concurrent heart rate variability (HRV) estimates. PPG devices commonly sample at ~20-100 Hz, where the minimum sampling frequency to derive valid PRV metrics is unknown. Further, due to different autonomic innervation, it is unknown if PRV metrics are harmonious between the cerebral and peripheral vasculature. Cardiac activity via electrocardiography (ECG) and PPG were obtained concurrently in 54 participants (29 females) in an upright orthostatic position. PPG data were collected at three anatomical locations: left third phalanx, middle cerebral artery, and posterior cerebral artery using a Finapres NOVA device and transcranial Doppler ultrasound. Data were sampled for five minutes at 1000 Hz and downsampled to frequencies ranging from 20 to 500 Hz. HRV (via ECG) and PRV (via PPG) were quantified and compared at 1000 Hz using Bland-Altman plots and coefficient of variation (CoV). A sampling frequency of ~100-200 Hz was required to produce PRV metrics with a bias of less than 2%, while a sampling rate of ~40-50 Hz elicited a bias smaller than 20%. At 1000 Hz, time- and frequency-domain PRV measures were slightly elevated compared to those derived from HRV (mean bias: ~1-8%). In conjunction with previous reports, PRV and HRV were not surrogate biomarkers due to the different nature of the collected waveforms. Nevertheless, PRV estimates displayed greater validity at a lower sampling rate compared to HRV estimates.

Imageless robotic total knee arthroplasty determines similar coronal plane alignment of the knee (CPAK) parameters to long leg radiographs

BACKGROUND

The coronal plane alignment of the knee (CPAK) classification was first developed using long leg radiographs (LLR) and has since been reported using image-based and imageless robotic total knee arthroplasty (TKA) systems. However, the correspondence between imageless robotics and LLR-derived CPAK parameters has yet to be investigated. This study therefore examined the differences in CPAK parameters determined with LLR and imageless robotic navigation using either generic or optimized cartilage wear assumptions.

METHODS

Medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were determined from the intraoperative registration data of 61 imageless robotic TKAs using either a generic 2 mm literature-based wear assumption (Navlit) or an optimized wear assumption (Navopt) found using an error minimization algorithm. MPTA and LDFA were also measured from preoperative LLR by two observers and intraclass correlation coefficients (ICCs) were calculated. MPTA, LDFA, joint line obliquity (JLO), and arithmetic hip-knee-ankle angle (aHKA) were compared between the robotic and the average LLR measurements over the two observers.

RESULTS

ICCs between observers for LLR were over 0.95 for MPTA, LDFA, JLO, and aHKA, indicating excellent agreement. Mean CPAK differences were not significant between LLR and Navlit (all differences within 0.6°, P > 0.1) or Navopt (all within 0.1°, P > 0.83). Mean absolute errors (MAE) between LLR and Navlit were: LDFA = 1.4°, MPTA = 2.0°, JLO = 2.1°, and aHKA = 2.7°. Compared to LLR, the generic wear classified 88% and the optimized wear classified 94% of knees within one CPAK group. Bland-Altman comparisons reported good agreement for LLR vs. Navlit and Navopt, with > 95% and > 91.8% of measurements within the limits of agreement across all CPAK parameters, respectively.

CONCLUSIONS

Imageless robotic navigation data can be used to calculate CPAK parameters for arthritic knees undergoing TKA with good agreement to LLR. Generic wear assumptions determined MPTA and LDFA with MAE within 2° and optimizing wear assumptions showed negligible improvement.

MyFitnessPal smartphone application: relative validity and intercoder reliability among dietitians in assessing energy and macronutrient intakes of selected Filipino adults with obesity

This study aimed to explore the validity of energy and macronutrient intake estimates provided by a popular nutrition tracking smartphone application. 37 obese Filipino adults and 3 nutritionist-dietitians participated in this study. Participants used MyFitnessPal to log their food intake for 5 days. They also completed paper-based food record forms at the same time. Dietitians then referred to each of the participants' completed food record forms to log the participants' food intakes and generated estimates of energy and nutrient intake using the same app. The researcher also referred to the participants' completed food record forms and generated energy and nutrient intake data using the Food Composition Tables (FCT)-the Philippine reference standard for estimating calorie and nutrient intakes. T-tests showed no statistical difference in energy and macronutrient data generated between participants and dietitians using MyFitnessPal app but Bland-Altman plots showed very weak to moderate agreements. T-tests revealed statistically significant difference between using the MyFitnessPal app and FCT in estimating energy, protein and fat intakes and Bland-Altman plots showed very weak to moderate agreement between MyFitnessPal and FCT. MyFitnessPal was found to underestimate the values for energy, carbohydrates and fat and overestimate values for protein when compared with estimates using FCT. Analysis of variance showed good intercoder reliability among dietitians, with the exception of fat intake estimates. The Goldberg approach showed very low likelihood of misreporting energy intake among the participants in this study. In this study, MyFitnessPal showed poor validity among Filipinos with obesity but with good reliability when used by dietitians. It also showed poor validity relative to the FCT. Prior nutrition knowledge is a factor in ensuring the accuracy of energy and nutrient intake data generated using MyFitnessPal app. It is recommended that users consult with dietitians for guidance on how to use these apps in weight management interventions.

Use of focus point for plane acquisition to improve reproducibility in fetal biometry

OBJECTIVE

To assess the reproducibility of ultrasound measurements of fetal biometry using a 'focus point' to assist the acquisition of the relevant plane.

METHODS

This was a study of 80 women with a singleton non-anomalous pregnancy who attended University College London Hospital, London, UK, between 18 and 37 weeks' gestation. Planes to measure head circumference (HC), abdominal circumference (AC) and femur length (FL) were obtained four times by two different sonographers with different levels of experience, who were blinded to one another; the first set of images was obtained with reference to a standard image, and the second set of images was obtained using the focus point technique. The focus point was defined as a unique fetal anatomical landmark in each plane (cavum septi pellucidi for HC, two-thirds of the umbilical vein for AC and one of the two extremities of the diaphysis for FL). Once identified, the focus point was maintained in view while the sonographer rotated the probe along three axes (x, y, z) to acquire the relevant plane. Sonographers were either in training or had > 3000 scans worth of experience. Intra- and interobserver reproducibility were assessed using Bland-Altman plots, and absolute values and percentages for mean difference and 95% limits of agreement (LoA) were reported.

RESULTS

Overall reproducibility was good, with all 95% LoA < 8%. Reproducibility was improved by use of the focus point compared with the standard technique for both intraobserver comparison (95% LoA, < 4% vs < 6%) and interobserver comparison (95% LoA, < 7% vs < 8%). These findings were independent of sonographer seniority and plane acquired.

CONCLUSIONS

Reproducibility of fetal biometry assessment is improved with use of the focus point for plane acquisition, regardless of sonographer experience. We propose that this method should be implemented in clinical practice and training programs in fetal biometry. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Agreement of zero-heat-flux thermometry with the oesophageal and tympanic core temperature measurement in patient receiving major surgery

To identify and prevent perioperative hypothermia, most surgical patients require a non-invasive, accurate, convenient, and continuous core temperature method, especially for patients undergoing major surgery. This study validated the precision and accuracy of a cutaneous zero-heat-flux thermometer and its performance in detecting intraoperative hypothermia. Adults undergoing major non-cardiac surgeries with general anaesthesia were enrolled in the study. Core temperatures were measured with a zero-heat-flux thermometer, infrared tympanic membrane thermometer, and oesophagal monitoring at 15-minute intervals. Taking the average value of temperature measured in the tympanic membrane and oesophagus as a reference, we assessed the agreement using the Bland-Altman analysis and linear regression methods. Sensitivity, specificity, and predictive values of detecting hypothermia were estimated. 103 patients and one thousand sixty-eight sets of paired temperatures were analyzed. The mean difference between zero-heat-flux and the referenced measurements was -0.03 ± 0.25 °C, with 95% limits of agreement (-0.52 °C, 0.47 °C) was narrow, with 94.5% of the differences within 0.5 °C. Lin's concordance correlation coefficient was 0.90 (95%CI 0.89-0.92). The zero-heat-flux thermometry detected hypothermia with a sensitivity of 82% and a specificity of 90%. The zero-heat-flux thermometer is in good agreement with the reference core temperature based on tympanic and oesophagal temperature monitoring in patients undergoing major surgeries, and appears high performance in detecting hypothermia.

CG02N Analyzer Accurately Measures Fibrinogen Level in Whole Blood in the Presence of Low- or High-Dose Heparin

Rapid fibrinogen (Fbg) evaluation is important in patients with massive bleeding during severe trauma and those undergoing major surgery. However, there are only a few studies on the point-of-care Fbg analyzer. In this study, we aimed to investigate the accuracy of Fbg level measured using CG02N, with whole blood contained in lithium-heparinized syringes with two different concentrations of heparin. Blood samples were collected in lithium-heparinized tubes, namely PREZA-PAK®II (low-dose heparin group [LG], 7 IU/mL) and Pro-Vent® Plus (high-dose heparin group [HG], 70.5 IU/mL). The Fbg levels in LG and HG were compared with those of citrated plasma Fbg (standard-Fbg). Strong correlations with respect to the Fbg level were observed between standard-Fbg and LG or HG (r = 0.968, p < 0.0001; r = 0.970, p < 0.0001, respectively). We demonstrated that the Fbg level in whole-blood samples was accurately assessed by CG02N and not affected by low- or high-dose heparin.

Discordance Between Invasive and NonInvasive Oxygen Saturation in Critically Ill COVID-19 Patients

OBJECTIVES

To investigate discordance in oxy-hemoglobin saturation measured both by pulse oximetry (SpO2) and arterial blood gas (ABG, SaO2) among critically ill coronavirus disease 2019 (COVID-19(+)) patients compared to COVID-19(-) patients.

METHODS

Paired SpO2 and SaO2 readings were collected retrospectively from consecutive adult admissions to four critical care units in the United States between March and May 2020. The primary outcome was the rate of discordance (|SaO2-SpO2|>4%) in COVID-19(+) versus COVID-19(-) patients. The odds each cohort could have been incorrectly categorized as having a PaO2/FiO2 above or below 150 by their SpO2: Fractional inhaled oxygen ratio (pulse oximetry-derived oxyhemoglobin saturation:fraction of inspired oxygen ratio [SF]) was examined. A multivariate regression analysis assessed confounding by clinical differences between cohorts including pH, body temperature, renal replacement therapy at time of blood draw, and self-identified race.

RESULTS

There were 263 patients (173 COVID-19(+)) included. The rate of saturation discordance between SaO2 and SpO2 in COVID-19(+) patients was higher than in COVID-19(-) patients (27.9% vs 16.7%, odds ratio [OR] 1.94, 95% confidence interval [CI]: 1.11 to 2.27). The average difference between SaO2 and SpO2 for COVID-19(+) patients was -1.24% (limits of agreement, -13.6 to 11.1) versus -0.11 [-10.3 to 10.1] for COVID-19(-) patients. COVID-19(+) patients had higher odds (OR: 2.61, 95% CI: 1.14-5.98) of having an SF that misclassified that patient as having a PaO2:FiO2 ratio above or below 150. There was not an association between discordance and the confounders of pH, body temperature, or renal replacement therapy at time of blood draw. After controlling for self-identified race, the association between COVID-19 status and discordance was lost.

CONCLUSIONS

Pulse oximetry was discordant with ABG more often in critically ill COVID-19(+) than COVID-19(-) patients. However, these findings appear to be driven by racial differences between cohorts.

Accuracy and User Acceptability of 24-hour Ambulatory Blood Pressure Monitoring by a Prototype Cuffless Multi-Sensor Device Compared to a Conventional Oscillometric Device

OBJECTIVE

24-hour ambulatory blood pressure monitoring (24ABPM) is state of the art in out-of-office blood pressure (BP) monitoring. Due to discomfort and technical limitations related to cuff-based 24ABPM devices, methods for non-invasive and continuous estimation of BP without the need for a cuff have gained interest. The main aims of the present study were to compare accuracy of a pulse arrival time (PAT) based BP-model and user acceptability of a prototype cuffless multi-sensor device (cuffless device), developed by Aidee Health AS, with a conventional cuff-based oscillometric device (ReferenceBP) during 24ABPM.

METHODS

Ninety-five normotensive and hypertensive adults underwent simultaneous 24ABPM with the cuffless device on the chest and a conventional cuff-based oscillometric device on the non-dominant arm. PAT was calculated using the electrocardiogram (ECG) and photoplethysmography (PPG) sensors incorporated in the chest-worn device. The cuffless device recorded continuously, while ReferenceBP measurements were taken every 20 minutes during daytime and every 30 minutes during nighttime. Two-minute PAT-based BP predictions corresponding to the ReferenceBP measurements were compared with ReferenceBP measurements using paired t-tests, bias, and limits of agreement.

RESULTS

Mean (SD) of ReferenceBP compared to PAT-based daytime and nighttime systolic BP (SBP) were 129.7 (13.8) mmHg versus 133.6 (20.9) mmHg and 113.1 (16.5) mmHg versus 131.9 (23.4) mmHg. Ninety-five % limits of agreements were [-26.7, 34.6 mmHg] and [-20.9, 58.4 mmHg] for daytime and nighttime SBP respectively. The cuffless device was reported to be significantly more comfortable and less disturbing than the ReferenceBP device during 24ABPM.

CONCLUSIONS

In the present study, we demonstrated that a general PAT-based BP model had unsatisfactory agreement with ambulatory BP during 24ABPM, especially during nighttime. If sufficient accuracy can be achieved, cuffless BP devices have promising potential for clinical assessment of BP due to the opportunities provided by continuous BP measurements during real-life conditions and high user acceptability.

Estimating Metabolic Energy Expenditure During Level Running in Healthy, Military-Age Women and Men

ABSTRACT

Looney, DP, Hoogkamer, W, Kram, R, Arellano, CJ, and Spiering, BA. Estimating metabolic energy expenditure during level running in healthy, military-age women and men. J Strength Cond Res 37(12): 2496-2503, 2023-Quantifying the rate of metabolic energy expenditure (Ṁ) of varied aerobic exercise modalities is important for optimizing fueling and performance and maintaining safety in military personnel operating in extreme conditions. However, although equations exist for estimating oxygen uptake during running, surprisingly, there are no general equations that estimate Ṁ. Our purpose was to generate a general equation for estimating Ṁ during level running in healthy, military-age (18-44 years) women and men. We compiled indirect calorimetry data collected during treadmill running from 3 types of sources: original individual subject data (n = 45), published individual subject data (30 studies; n = 421), and published group mean data (20 studies, n = 619). Linear and quadratic equations were fit on the aggregated data set using a mixed-effects modeling approach. A chi-squared (χ2) difference test was conducted to determine whether the more complex quadratic equation was justified (p < 0.05). Our primary indicator of model goodness-of-fit was the root-mean-square deviation (RMSD). We also examined whether individual characteristics (age, height, body mass, and maximal oxygen uptake [V̇O2max]) could minimize prediction errors. The compiled data set exhibited considerable variability in Ṁ (14.54 ± 3.52 W·kg-1), respiratory exchange ratios (0.89 ± 0.06), and running speeds (3.50 ± 0.86 m·s-1). The quadratic regression equation had reduced residual sum of squares compared with the linear fit (χ2, 3,484; p < 0.001), with higher combined accuracy and precision (RMSD, 1.31 vs. 1.33 W·kg-1). Age (p = 0.034), height (p = 0.026), and body mass (p = 0.019) were associated with the magnitude of under and overestimation, which was not the case for V̇O2max (p = 0.898). The newly derived running energy expenditure estimation (RE3) model accurately predicts level running Ṁ at speeds from 1.78 to 5.70 m·s-1 in healthy, military-age women and men. Users can rely on the following equations for improved predictions of running Ṁ as a function of running speed (S, m·s-1) in either watts (W·kg-1 = 4.43 + 1.51·S + 0.37·S2) or kilocalories per minute (kcal·kg-1·min-1 = 308.8 + 105.2·S + 25.58·S2).

[Adaptation of the Standardized Patient Evaluation of Eye Dryness Questionnaire to European Portuguese (SPEED-Vp) in a Non-Clinical Sample]

INTRODUCTION

The aim of this study was to translate and adapt the Standardized Patient Evaluation of Eye Dryness questionnaire to European Portuguese, as well as assess the psychometric performance of the translated version, including repeatability and agreement.

MATERIAL AND METHODS

The original Standardized Patient Evaluation of Eye Dryness - SPEED questionnaire was translated and adapted to the Portuguese cultural context by following a scientifically valid methodology commonly used in the process of adapting tools to other cultures and languages. The questionnaire resulting from the translation into the new language was subject to a pre-test where the comments of the participants were written and considered for the final version of the questionnaire. For the scale validation of the final version of the translated questionnaire, 89 subjects from a non-clinical population, aged 18 to 84 years, were asked to answer the questionnaire (61% were women). One week later, the same questionnaire was repeated by 63 subjects. The internal reliability of the questionnaire was analyzed by Cronbach's alpha, temporal stability by test-retest, and analysis of agreement between measures by the Bland-Altman method.

RESULTS

The internal consistency of the translated questionnaire, SPEED-vP was high (α = 0.871) and all questionnaire items contributed to an increase in this index. This consistency was also confirmed to be high in the retest (α = 0.856) and when the sample was stratified by age and sex. The SPEED-complete questionnaire also showed high consistency (α = 0.88). The repeatability of the instrument was high (ICC 0.933; 95% CI: 0.899 and 0.960) and the Bland-Altman plot revealed good agreement between measures.

CONCLUSION

The Standardized Patient Evaluation of Eye Dryness in Portuguese (SPEED-vP) showed good psychometric properties for the Portuguese population. Therefore, the translated version of the SPEED-vP questionnaire could be used to quantitatively measure the presence of dry eye symptoms in the Portuguese population.

Pulse rate variability: An alternative to heart rate variability in adults with spinal cord injury

Pulse rate variability (PRV) is often used as an alternative to heart rate variability (HRV) to measure psychophysiological function. However, its validity to do so is unclear, especially in adults with spinal cord injury (SCI). This study compared PRV and HRV in adults with higher-level SCI (SCI-H, n = 23), lower-level SCI (SCI-L, n = 22), and able-bodied participants (AB n = 44), in a seated position as a function of performance in a reactivity task (Oxford Sleep Resistance Test: OSLER). PRV and HRV was measured using reflective finger-based photoplethysmography (PPG) and electrocardiography, respectively, at baseline, immediately post-OSLER, and after five-minute recovery. Agreement between PRV and HRV was determined by Bland-Altman analysis and differences between PRV and HRV over time by linear mixed effects model (LMM) analysis. Concurrent validity was assessed through correlation analyses between PRV and HRV. Additional correlation analyses were performed with psychosocial factors. Results indicated insufficient to moderate agreement between PRV and HRV. LMM analyses indicated no differences over time for standard deviation of normal-to-normal intervals and low-frequency power but significant differences for root mean square of successive differences and high frequency power. Nevertheless, PRV and HRV were highly correlated (Median r = .878 (.675-.990)) during all assessment periods suggesting sufficient concurrent validity. Similar correlation patterns were also found for PRV and HRV with psychosocial outcomes. While differences existed, results suggest PRV derived from reflective finger-based PPG is a valid proxy of HRV in tracking psychophysiological function in adults with SCI and could therefore be used as a more accessible monitoring tool.

Fast in vivo assay of creatine kinase activity in the human brain by 31 P magnetic resonance fingerprinting

A new and efficient magnetisation transfer 31 P magnetic resonance fingerprinting (MT-31 P-MRF) approach is introduced to measure the creatine kinase metabolic ratek CK between phosphocreatine (PCr) and adenosine triphosphate (ATP) in human brain. The MRF framework is extended to overcome challenges in conventional 31 P measurement methods in the human brain, enabling reduced acquisition time and specific absorption rate (SAR). To address the challenge of creating and matching large multiparametric dictionaries in an MRF scheme, a nested iteration interpolation method (NIIM) is introduced. As the number of parameters to estimate increases, the size of the dictionary grows exponentially. NIIM can reduce the computational load by breaking dictionary matching into subsolutions of linear computational order. MT-31 P-MRF combined with NIIM providesT 1 PCr ,T 1 ATP andk CK estimates in good agreement with those obtained by the exchange kinetics by band inversion transfer (EBIT) method and literature values. Furthermore, the test-retest reproducibility results showed that MT-31 P-MRF achieves a similar or better coefficient of variation (<12%) forT 1 ATP andk CK measurements in 4 min 15 s, than EBIT with 17 min 4 s scan time, enabling a fourfold reduction in scan time. We conclude that MT-31 P-MRF in combination with NIIM is a fast, accurate, and reproducible approach for in vivok CK assays in the human brain, which enables the potential to investigate energy metabolism in a clinical setting.

Validation of the Body Scan®, a new device to detect small fiber neuropathy by assessment of the sudomotor function: agreement with the Sudoscan®

Background

Sudomotor dysfunction is one of the earliest manifestations of small fiber neuropathy (SFN), reflecting the alteration of sympathetic C fiber innervation of the sweat glands. Among other techniques, such innervation can be assessed by measuring electrochemical skin conductance (ESC) in microsiemens (μS). In this study, ESC was measured at the feet to detect distal SFN. For this objective, the performance of a new device, the Body Scan® (Withings, France), intended for home use, was compared with that of a reference device, the Sudoscan® (Impeto Medical, France), which requires a hospital setting.

Methods

In patients with diabetes with or without neuropathy or non-diabetic patients with lower-limb neuropathy, the diagnostic performance of the Body Scan® measurement was assessed by calculating its sensitivity (Se) and specificity (Sp) to detect at least moderate SFN (Se70 and Sp70), defined by a value of feet ESC ≤ 70 μS and > 50 μS on the Sudoscan® measure, or severe SFN (Se50 and Sp50), defined by a value of feet ESC ≤ 50 μS on the Sudoscan® measure. The agreement between the two devices was assessed with the analysis of Bland-Altman plots, mean absolute error (MAE), and root mean squared error (RMSE) calculations. The repeatability of the measurements was also compared between the two devices.

Results

A total of 147 patients (52% men, mean age 59 years old, 76% diabetic) were included in the analysis. The sensitivity and specificity to detect at least moderate or severe SFN were: Se70 = 0.91 ([0.83, 0.96]), Sp70 = 0.97 ([0.88, 0.99]), Se50 = 0.91 ([0.80, 0.98]), and Sp50 = 0.99 ([0.94, 1]), respectively. The bias and 95% limits of agreement were 1.5 [-5.4, 8.4]. The MAE was 2.9 and the RMSE 3.8. The intra-sample variability was 2.0 for the Body Scan® and 2.3 for the Sudoscan®.

Conclusion

The ESC measurements provided by the Body Scan® were in almost perfect agreement with those provided by the reference device, the Sudoscan®, which validates the accuracy of the Body Scan® for the detection of SFN. By enabling simple, rapid, and autonomous use by the patient at home, this new technique will facilitate screening and monitoring of SFN in daily practice.

Clinical trial registration

ClinicalTrials.gov, identifier NCT05178459.

Comparative analysis between different volumetric methods on measuring intracranial hemorrhage incorporating roundness index

Intracranial hematoma (ICH) volume is considered a predictor of clinical outcome and mortality rate in ICH patients with traumatic brain injury (TBI). The ABC/2 method for ICH volume is the standard method used to date, however, its level of accuracy has been questioned in some studies. This study compared the performance of the ABC/2 method with planimetry and truncated pyramidal methods to highlight the potential of the planimetry method applied with automatic segmentation for evaluation of epidural hematoma (EDH) and intraparenchymal hematoma (IPH) volume. Six different phantoms were designed to evaluate the accuracy of volume estimation methods. 221 hematoma regions extracted from CT scans of 125 patients with head injury were also used to analyze the efficiency. The roundness index was utilized for the quantification of the ellipsoid-like shape. Regions of EDH and IPH on the CT scans were annotated by radiologists. The estimation errors for each method were statistically analyzed and compared. In addition, the relationship between the errors and roundness index was examined. The planimetry method showed the lowest relative error on phantom data. In the case of the CT scan data, the truncated pyramidal method resulted in the underestimation of the volumes of EDH and IPH. Meanwhile, the ABC/2, through principal component analysis (PCA) in the two-dimensional and PCA in the three-dimensional methods, resulted in a significant overestimation. In addition, both these approaches produced relative errors that showed a correlation with the roundness indexes for IPH. In comparison to other methods, the planimetry method had the lowest level of error with regards to calculation of the volume and it was also independent of the hematoma shape. The planimetry method, therefore, has the potential to serve as a useful tool for the assessment of ICH volume in TBI patients by using a deep learning system.

Utility of continuous pulse CO-oximetry for hemoglobin monitoring in pediatric patients with solid organ injuries at level 1 trauma centers: A pilot study

INTRODUCTION

Hemorrhage is a major cause of preventable death in injured children. Monitoring after admission often requires multiple blood draws, which have been shown to be stressful in pediatric patients. The Rainbow-7 device is a continuous pulse CO-oximeter that measures multiple wavelengths of light, permitting continuous estimation of the total hemoglobin (Hb) level. The purpose of this study was to evaluate the utility of the noninvasive Hb measurement for monitoring pediatric trauma patients admitted with solid organ injury.

METHODS

This is a prospective, dual-center, observational trial for patients younger than age 18 years admitted to a Level I pediatric trauma center. Following admission, blood was routinely measured as per current solid organ injury protocols. Noninvasive Hb monitoring was initiated after admission. Time-synced data for Hb levels were compared with that taken using blood draws. Data were evaluated using bivariate correlation, linear regression, and Bland-Altman analysis.

RESULTS

Over a 1-year period, 39 patients were enrolled. The mean ± SD age was 11 ± 3.8 years. Forty-six percent (n = 18) of patients were male. The mean ± SD Injury Severity Score was 19 ± 13. The average change in Hb levels between laboratory measurements was -0.34 ± 0.95 g/dL, and the average change in noninvasive Hb was -0.12 ± 1.0 g/dL per measurement. Noninvasive Hb values were significantly correlated with laboratory measurements ( p < 0.001). Trends in laboratory Hb measurements were highly correlated with changes in noninvasive levels ( p < 0.001). Bland-Altman analysis demonstrated similar deviation from the mean throughout the range of Hb values, but the differences between measurements were increased by anemia, African American race, and elevated shock index, pediatric age-adjusted score and Injury Severity Score.

CONCLUSION

Noninvasive Hb values demonstrated correlation with measured Hb concentration as isolated measurements and trends, although results were affected by skin pigmentation, shock, and injury severity. Given the rapid availability of results and the lack of requirement of venipuncture, noninvasive Hb monitoring may be a valuable adjunct for pediatric solid organ injury protocols. Further study is required to determine its role in management.

LEVEL OF EVIDENCE

Dianostic Test or Criteria; Level III.

Evaluation of Rapid Multiplex Reverse Transcription-Quantitative Polymerase Chain Reaction Assays for SARS-CoV-2 Detection in Individual and Pooled Samples

Although coronavirus disease 2019 (COVID-19) is no longer a Public Health Emergency of International Concern (PHEIC), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has had a vast impact to date. Hence, continuous management is required, given the uncertainty caused by the potential evolution of SARS-CoV-2. Reverse transcription-quantitative PCR (RT-qPCR) diagnosis has been fundamental in overcoming this issue. In this study, the performances of two rapid RT-qPCR assays (Real-Q Direct SARS-CoV-2 Detection Kit and Allplex™ SARS-CoV-2 fast PCR Assay) with short PCR times were comparatively evaluated using a STANDARD M nCoV Real-Time Detection Kit (STANDARD M, conventional RT-qPCR assay). All kits showed a limit of detection values (102-103 copies/reaction). The evaluation showed that the two rapid assay tests had ≥97.89% sensitivity and ≥99.51% specificity (κ = 0.98) for individual samples and ≥97.32% sensitivity and ≥97.67% specificity for pooled samples compared to STANDARD M. These results indicate that the two rapid RT-qPCR kits, which showed significant time reduction in performance, are as effective as a conventional RT-qPCR assay. They are likely to increase not only the number of tests that can be performed but also the efficiency of sustainable management of COVID-19 in the long term.

Standing Pelvic Tilt Is Associated With Dynamic Pelvic Tilt During Running When Measured by 3-Dimensional Motion Capture

Standing pelvic tilt (PT) is related to biomechanics linked with increased risk of injury such as dynamic knee valgus. However, there is limited evidence on how standing PT relates to dynamic PT and whether the palpation meter (PALM), a tool to measure standing PT, is valid against 3-dimensional (3D) motion analysis. The purposes of this study were to (1) determine the criterion validity of the PALM for measuring standing PT and (2) identify the relationship between standing PT and dynamic PT during running. Participants (n = 25; 10 males and 15 females) had their standing PT measured by the PALM and 3D motion analysis. Dynamic PT variables were defined at initial contact and toe off. No relationship between the 2 tools was found. Significant large positive relationships between standing PT and PT at initial contact (r = .751, N = 25, P < .001) and PT at toe off (r = .761, N = 25, P < .001) were found. Since no relationship was found between standing PT measured by the PALM and 3D motion analysis, the PALM is not a valid alternative to 3D motion analysis. Clinicians may be able to measure standing PT and gain valuable information on dynamic PT, allowing clinicians to quickly assess whether further biomechanical testing is needed.

Assessment of a Novel Semi-Automated Algorithm for the Quantification of the Parafoveal Capillary Network

Introduction

We present a novel semi-automated computerized method for the detection and quantification of parafoveal capillary network (PCN) in fluorescein angiography (FA) images.

Material and Methods

An algorithm detecting the superficial parafoveal capillary bed in high-resolution grayscale FA images and creating a one-pixel-wide PCN skeleton was developed using MatLab software. In addition to PCN detection, capillary density and branch point density in two circular areas centered on the center of the foveal avascular zone of 500μm and 750μm radius was calculated by the algorithm. Three consecutive FA images with distinguishable PCN from 56 eyes from 56 subjects were used for analysis. Both manual and semi-automated detection of the PCN and branch points was performed and compared. Three different intensity thresholds were used for the PCN detection to optimize the method defined as mean(I)+0.05*SD(I), mean(I) and mean(I)-0.05*SD(I), where I is the grayscale intensity of each image and SD the standard deviation. Limits of agreement (LoA), intraclass correlation coefficient (ICC) and Pearson's correlation coefficient (r) were calculated.

Results

Using mean(I)-0.05*SD(I) as threshold the average difference in PCN density between semi-automated and manual method was 0.197 (0.316) deg^-1 at 500μm radius and 0.409 (0.562) deg^-1 at 750μm radius. The LoA were -0.421 to 0.817 and -0.693 to 1.510 deg^-1, respectively. The average difference of branch point density between semi-automated and manual method was zero for both areas; LoA were -0.001 to 0.002 and -0.001 to 0.001 branch points/degrees², respectively. The other two intensity thresholds provided wider LoA for both metrics. The semi-automated algorithm showed great repeatability (ICC>0.91 in the 500μm radius and ICC>0.84 in the 750μm radius) for both metrics.

Conclusion

This semi-automated algorithm seems to provide readings in agreement with those of manual capillary tracing in FA. Larger prospective studies are needed to confirm the utility of the algorithm in clinical practice.

Unsupervised Gait Event Identification with a Single Wearable Accelerometer and/or Gyroscope: A Comparison of Methods across Running Speeds, Surfaces, and Foot Strike Patterns

We evaluated 18 methods capable of identifying initial contact (IC) and terminal contact (TC) gait events during human running using data from a single wearable sensor on the shank or sacrum. We adapted or created code to automatically execute each method, then applied it to identify gait events from 74 runners across different foot strike angles, surfaces, and speeds. To quantify error, estimated gait events were compared to ground truth events from a time-synchronized force plate. Based on our findings, to identify gait events with a wearable on the shank, we recommend the Purcell or Fadillioglu method for IC (biases +17.4 and -24.3 ms; LOAs -96.8 to +131.6 and -137.0 to +88.4 ms) and the Purcell method for TC (bias +3.5 ms; LOAs -143.9 to +150.9 ms). To identify gait events with a wearable on the sacrum, we recommend the Auvinet or Reenalda method for IC (biases -30.4 and +29.0 ms; LOAs -149.2 to +88.5 and -83.3 to +141.3 ms) and the Auvinet method for TC (bias -2.8 ms; LOAs -152.7 to +147.2 ms). Finally, to identify the foot in contact with the ground when using a wearable on the sacrum, we recommend the Lee method (81.9% accuracy).

Comparison between Capillary and Serum Lactate Levels in Predicting Short-Term Mortality of Septic Patients at the Emergency Department

Sepsis is a time-dependent and life-threating condition related to macro- and micro-circulatory impairment leading to anaerobic metabolism and lactate increase. We assessed the prognostic accuracy of capillary lactates (CLs) vs. serum ones (SLs) on 48-h and 7-day mortality in patients with suspected sepsis. This observational, prospective, single-centre study was conducted between October 2021 and May 2022. Inclusion criteria were: (i) suspect of infection; (ii) qSOFA ≥ 2; (iii) age ≥ 18 years; (iv) signed informed consent. CLs were assessed with LactateProTM2^®. 203 patients were included: 19 (9.3%) died within 48 h from admission to the Emergency Department, while 28 (13.8%) within 7 days. Patients deceased within 48 h (vs. survived) had higher CLs (19.3 vs. 5 mmol/L, p < 0.001) and SLs (6.5 vs. 1.1 mmol/L, p = 0.001). The best CLs predictive cut-off for 48-h mortality was 16.8 mmol/L (72.22% sensitivity, 94.02% specificity). Patients within 7 days had higher CLs (11.5 vs. 5 mmol/L, p = 0.020) than SLs (2.75 vs. 1.1 mmol/L, p < 0.001). The multivariate analysis confirmed CLs and SLs as independent predictors of 48-h and 7-day mortality. CLs can be a reliable tool for their inexpensiveness, rapidity and reliability in identifying septic patients at high risk of short-term mortality.

Wearable cardiorespiratory monitoring with stretchable elastomer optical fiber

This work presents a stretchable elastomer optical fiber sensor incorporated into a belt for respiratory rate (RR) and heart rate (HR) monitoring. Different materials and shapes of prototypes designed were tested in terms of performance and the best choice was identified. The optimal sensor was tested by 10 volunteers to evaluate the performance. The proposed elastomer optical fiber sensor can achieve simultaneous measurement of RR and HR in different body positions, and also ballistocardiography (BCG) signal measurement in the lying position. The sensor has good accuracy and stability, with maximum errors of 1 bpm and 3 bpm for RR and HR, respectively, and average weighted mean absolute percentage error (MAPE) of 5.25% and root mean square error (RMSE) of 1.28 bpm. Moreover, the results of the Bland-Altman method showed good agreement of the sensor with manual counting of RR and with electrocardiogram (ECG) measurements of HR.

Prospective Validation of 2B-Cool : Integrating Wearables and Individualized Predictive Analytics to Reduce Heat Injuries

INTRODUCTION

An uncontrollably rising core body temperature (T C ) is an indicator of an impending exertional heat illness. However, measuring T C invasively in field settings is challenging. By contrast, wearable sensors combined with machine-learning algorithms can continuously monitor T C nonintrusively. Here, we prospectively validated 2B-Cool , a hardware/software system that automatically learns how individuals respond to heat stress and provides individualized estimates of T C , 20-min ahead predictions, and early warning of a rising T C .

METHODS

We performed a crossover heat stress study in an environmental chamber, involving 11 men and 11 women (mean ± SD age = 20 ± 2 yr) who performed three bouts of varying physical activities on a treadmill over a 7.5-h trial, each under four different clothing and environmental conditions. Subjects wore the 2B-Cool system, consisting of a smartwatch, which collected vital signs, and a paired smartphone, which housed machine-learning algorithms and used the vital sign data to make individualized real-time forecasts. Subjects also wore a chest strap heart rate sensor and a rectal probe for comparison purposes.

RESULTS

We observed very good agreement between the 2B-Cool forecasts and the measured T C , with a mean bias of 0.16°C for T C estimates and nearly 75% of measurements falling within the 95% prediction intervals of ±0.62°C for the 20-min predictions. The early-warning system results for a 38.50°C threshold yielded a 98% sensitivity, an 81% specificity, a prediction horizon of 35 min, and a false alarm rate of 0.12 events per hour. We observed no sex differences in the measured or predicted peak T C .

CONCLUSION

2B-Cool provides early warning of a rising T C with a sufficient lead time to enable clinical interventions and to help reduce the risk of exertional heat illness.