Physiological measurement最新文献

Objective.Obstructive sleep apnea (OSA) is associated with deficits in vigilance. This work explored the temporal patterns of OSA-related events during sleep and vigilance levels measured by the psychomotor vigilance test (PVT) in patients undergoing polysomnography (PSG) for suspected OSA.Approach.The PVT was conducted prior to in-laboratory PSG for 80 patients suspected of having OSA. Three groups were formed based on PVT-RT-outcomes and participants were randomly allocated into Training (n= 55) and Test (n= 25) samples. Sleep epochs of non-rapid-eye movement (NREM) electroencephalographic (EEG) asynchrony data, and REM and NREM data for respiratory, arousal, limb movement and desaturation events were analysed. The data were segmented by sleep stage, by sleep blocks (SB) of stable Stage N2, Stage N3, mixed-stage NREM sleep (NXL), and, by Time of Night (TN) across sleep. Models associating this data with PVT groups were developed and tested.Main Results.Amodel using NREM EEG asynchrony data segmented by SB and TN achieved 81.9% accuracy in the Test Cohort. Models based on interhemispheric asynchrony SB data and OSA data segmented by TN achieved 80.6% and 79.5% respectively.Significance.Novel data segmentation methods via blocks of NXL and TN have improved our understanding of the relationship between sleep, OSA and vigilance.

Objective. Pulse pressure waves contain information about human physiology. There is a need for a simple, accurate way to know cardiovascular health in the clinic, so as to realize the implementation of convenient and effective early health monitoring for patients with arteriosclerosis.Approach. This study proposes an arteriosclerosis assessment method based on fitting a lognormal function, along with improving a conventional electronic sphygmomanometer. During the deflation phase of blood pressure measurement, the cuff pressure was kept constant (40 mmHg) and an additional 10 s of pulse signal was acquired. To derive the pulse pressure waveforms for a single cycle, the acquired pulse data of 101 cases were preprocessed in this study, including filtering for noise removal, onset point identification, removal of baseline drift, and normalization. In this study, an improved pulse resolution algorithm is proposed for the multimodal problem of the pulse wave, combining waveform matching and threshold setting, and finally obtaining the resolution parameters of the lognormal function with an average error less than 1.5%.Main results. According to the correlation analysis, the resolved parametersA₁,W₂,C₂,W₃, andC₃were significantly correlated with brachial-ankle Pulse Wave Velocity, and the absolute correlation range in 0.17-0.53, which can be used as a reference index for arteriosclerosis. An arteriosclerosis assessment model was constructed based on the support vector mechanism, and the prediction accuracy was 91.1%.Significance. This study provides a new solution idea for the arteriosclerosis assessment method as well as the pulse resolution algorithm, which has a greater reference value.

Objective.Sulfur hexafluoride (SF₆) multiple-breath washout (MBW) assesses ventilation inhomogeneity, as an early marker of obstructive respiratory diseases. Primary outcomes are customarily washout-derived, and it is unclear whether the preceding SF₆-washin can provide similar estimates. We aimed to assess comparability of primary SF₆-MBW outcomes between washin and washout phases of infant SF₆-MBW data measured with the WBreath (ndd Medizintechnik AG, Zurich, Switzerland) and Spiroware (Eco Medics AG, Duernten, Switzerland) MBW-setups, respectively.Approach.We assessed mean relative differences in lung clearance index (LCI) and functional residual capacity (FRC) between the washin and washout of existing SF₆-MBW data from healthy infants and infants with cystic fibrosis (CF). We assessed whether these differences exceeded the mean relative within-test between-trial differences of washout-derived outcomes, which can be attributed to natural variability. We also explored non-physiological factors using a pediatric lung simulator.Main results.LCI and FRC from washin and washout were not comparable, for both setups. The mean difference (SD) in LCI between washin and washout was 2.3(10.8)% for WBreath and -9.7(8.0)% for Spiroware, while in FRC it was -4.7(8.4)% for WBreath and -2.3(9.7)% for Spiroware. These differences exceeded the within-test between-trial differences in washout-derived outcomes. Outcomes from washin and washout were also not comparable in a pediatric lung simulator.Significance.Outcomes of the washin and washout were not comparable due to an interplay of physiological and non-physiological factors, and cannot be used interchangeably.

Objective. Pendelluft is the movement of air between lung regions, and electrical impedance tomography (EIT) has shown an ability to detect and monitor it.Approach.In this note, we propose a functional EIT measure which quantifies the reverse airflow seen in pendelluft: theFraction of Reverse Impedance Change(FRIC).MainResults. FRIC measures the fraction of reverse flow in each pixel waveform (as an image) or globally (as a single parameter).Significance. Such a measure is designed to be a more specific measure than previous approaches, to enable comparative studies of the pendelluft, and to help clarify the effect of ventilation strategies.

The radial artery, one of the terminal branches of the forearm, is utilized for vascular access and in various non-invasive measurement method, providing crucial medical insights. Various sensor technologies have been developed, each suited to specific characterization requirements. The work presented in this paper is based on a systematic literature review of the main publications relating to this topic. Analysis of the forearm vascular system complex array of anatomical structures shows that the radial artery can be characterized by its size, position, elasticity, tissue evaluation, blood flow and blood composition. The survey of medical procedures for patient monitoring, diagnosis and pre-operative validation shows the use of measures for pulse wave, blood pressure, heart rate, skin temperature, tissue response,…By exploring sensor technologies used for artery characterization, we produce a synthesis of measurement principles, measured phenomena and measurement accuracy for capacitive, piezoresistive, bioimpedance, thermography, fiber optic based, piezoelectric and photoacoustic sensors. A comparative study is conducted for sensor technologies by considering the metrics of the information to be collected and the associated accuracy as well as the portability, the complexity of the processing, the cost and the mode of contact with the arm. Finally, a comprehensive framework is proposed to facilitate informed decisions in the development of medical devices tailored to specific characterization needs.

Objective.Continuous monitoring of blood pressure (BP) is crucial for daily healthcare. Although invasive methods provide accurate continuous BP measurements, they are not suitable for routine use. Photoplethysmography (PPG), a non-invasive technique that detects changes in blood volume within the microcirculation using light, shows promise for BP measurement. The primary goal of this study is to develop a novel cuffless method based on PPG for accurately estimating continuous BP.Approach.We introduce BP-Diff, an end-to-end method for cuffless continuous BP waveform estimation utilizing a conditional diffusion probability model combined with a U-Net architecture. This approach takes advantage of the stochastic properties of diffusion models and the strong feature representation capabilities of U-Net. It integrates the continuous BP waveform as the initial status and uses the PPG signal and its derivatives as conditions to guide the training and sampling process.Main results.BP-Diff was evaluated using both uncalibrated and calibrated schemes. The results indicate that, when uncalibrated, BP-Diff can accurately track BP dynamics, including peak and valley positions, as well as timing. After calibration, BP-Diff achieved highly accurate BP estimations. The mean absolute error of the estimated BP waveforms, along with the systolic BP, diastolic BP, and mean arterial pressure from the calibrated BP-Diff model, were 2.99 mmHg, 2.6 mmHg, 1.4 mmHg, and 1.44 mmHg, respectively. Consistency tests, including Bland-Altman analysis and Pearson correlation, confirmed its high reliability compared to reference BP. BP-Diff meets the American Association for Medical Instrumentation standards and has achieved a Grade A from the British Hypertension Society.Significance.This study utilizes PPG signals to develop a novel cuffless continuous BP measurement method, demonstrating superiority over existing approaches. The method is suitable for integration into wearable devices, providing a practical solution for continuous BP monitoring in everyday healthcare.

Objective.The accurate temporal analysis of muscle activations is of great importance in several research areas spanning from the assessment of altered muscle activation patterns in orthopaedic and neurological patients to the monitoring of their motor rehabilitation. Several studies have highlighted the challenge of understanding and interpreting muscle activation patterns due to the high cycle-by-cycle variability of the sEMG data. This makes it difficult to interpret results and to use sEMG signals in clinical practice. To overcome this limitation, this study aims at presenting a toolbox to help scientists easily characterize and assess muscle activation patterns during cyclical movements.Approach.CIMAP(Clustering for the Identification of Muscle Activation Patterns) is an open-source Python toolbox based on agglomerative hierarchical clustering that aims at characterizing muscle activation patterns during cyclical movements by grouping movement cycles showing similar muscle activity.Main results.From muscle activation intervals to the graphical representation of the agglomerative hierarchical clustering dendrograms, the proposed toolbox offers a complete analysis framework for enabling the assessment of muscle activation patterns. The toolbox can be flexibly modified to comply with the necessities of the scientist.CIMAPis addressed to scientists of any programming skill level working in different research areas such as biomedical engineering, robotics, sports, clinics, biomechanics, and neuroscience. CIMAP is freely available on GitHub (https://github.com/Biolab-PoliTO/CIMAP).Significance.CIMAPtoolbox offers scientists a standardized method for analyzing muscle activation patterns during cyclical movements.

Objective.Pediatric patients undergoing medical procedures often grapple with preoperative anxiety, which can impact postoperative outcomes. While healthcare providers subjectively assess anxiety, objective quantification tools remain limited. This study aimed to evaluate two objective measures-cardiac index (CI) and heart rate (HR) in comparison with validated subjective assessments, the modified Yale Preoperative Anxiety Scale (mYPAS) and the numeric rating scale (NRS).Approach.In this prospective, observational cohort study, children ages 5-17 undergoing ambulatory endoscopy under general anesthesia underwent simultaneous measurement of objective and subjective measures at various time points: baseline, intravenous placement, two-minutes post-IV placement, when departing the preoperative bay, and one-minute prior to anesthesia induction.Main Results.Of the 86 enrolled patients, 77 had analyzable CI data and were included in the analysis. The median age was 15 years (interquartile range 13, 16), 55% were female, and most were American Society of Anesthesiologists (ASA) Physical Status 2 (64%), and had previous endoscopies (53%). HR and CI correlated overall (r= 0.65, 95% CI: 0.62, 0.69;p< 0.001), as did NRS and mYPAS (r= 0.39, 95% CI: 0.34, 0.44;p< 0.001). The correlation between HR and CI was stronger with NRS (r= 0.24, 95% CI: 0.19, 0.29;p< 0.001; andr= 0.13, 95% CI: 0.07, 0.19;p< 0.001, respectively) than with mYPAS (r= 0.06, 95% CI: 0.00, 0.11;p= 0.046; andr= 0.08, 95% CI: 0.02, 0.14;p= 0.006, respectively). The correlation with mYPAS for both HR and CI varied significantly in both direction and magnitude across the different time points.Significance.A modest yet discernable correlation exists between objective measures (HR and CI) and established subjective anxiety assessments.

Objective.This study examined sex-related differences in fatigability and neuromuscular responses using surface electromyographic (sEMG) and mechanomyographic (sMMG) amplitude (AMP) and frequency (MPF) during fatiguing, maximal, bilateral isometric leg extensions.Approach.Twenty recreationally active males and females with resistance training experience performed continuous, maximal effort, bilateral isometric leg extensions until their force reduced by 50%. Linear mixed effect models analyzed patterns of force, sEMG, and sMMG AMP and MPF responses in the dominant limb. An independent samples t-test compared time-to-task failure (TTF) between sexes.Main Results.There were no significant differences in TTF between males and females. However, males experienced a greater rate of force loss compared to females. Furthermore, sEMG AMP and MPF and sMMG AMP responses followed similar linear trends for both sexes, while sMMG MPF showed non-linear responses with sex-dependent differences.Significance.These data suggest that although TTF was similar, males had a higher rate of force reduction, likely due to greater absolute strength. Furthermore, despite parallel changes in sEMG AMP and MPF, as well as sMMG AMP, the divergent responses observed in sMMG MPF highlight sex-dependent differences in how males and females experience changes in the firing rates of active motor units during sustained maximal contractions.