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1.
Microcirculation ; 31(5): e12854, 2024 07.
Artigo em Inglês | MEDLINE | ID: mdl-38690631

RESUMO

OBJECTIVE: Designing physiologically adequate microvascular trees is of crucial relevance for bioengineering functional tissues and organs. Yet, currently available methods are poorly suited to replicate the morphological and topological heterogeneity of real microvascular trees because the parameters used to control tree generation are too simplistic to mimic results of the complex angiogenetic and structural adaptation processes in vivo. METHODS: We propose a method to overcome this limitation by integrating a conditional deep convolutional generative adversarial network (cDCGAN) with a local fractal dimension-oriented constrained constructive optimization (LFDO-CCO) strategy. The cDCGAN learns the patterns of real microvascular bifurcations allowing for their artificial replication. The LFDO-CCO strategy connects the generated bifurcations hierarchically to form microvascular trees with a vessel density corresponding to that observed in healthy tissues. RESULTS: The generated artificial microvascular trees are consistent with real microvascular trees regarding characteristics such as fractal dimension, vascular density, and coefficient of variation of diameter, length, and tortuosity. CONCLUSIONS: These results support the adoption of the proposed strategy for the generation of artificial microvascular trees in tissue engineering as well as for computational modeling and simulations of microcirculatory physiology.


Assuntos
Simulação por Computador , Microcirculação , Microvasos , Microvasos/fisiologia , Microvasos/anatomia & histologia , Humanos , Microcirculação/fisiologia , Modelos Cardiovasculares , Fractais
2.
Blood Purif ; 53(9): 704-715, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38865971

RESUMO

INTRODUCTION: Continuous renal replacement therapy (CRRT) is a primary form of renal support for patients with acute kidney injury in an intensive care unit. Making an accurate decision of discontinuation is crucial for the prognosis of patients. Previous research has mostly focused on the univariate and multivariate analysis of factors in CRRT, without the capacity to capture the complexity of the decision-making process. The present study thus developed a dynamic, interpretable decision model for CRRT discontinuation. METHOD: The study adopted a cohort of 1,234 adult patients admitted to an intensive care unit in the MIMIC-IV database. We used the eXtreme Gradient Boosting (XGBoost) machine learning algorithm to construct dynamic discontinuation decision models across 4 time points. SHapley Additive exPlanation (SHAP) analysis was conducted to exhibit the contributions of individual features to the model output. RESULT: Of the 1,234 included patients with CRRT, 596 (48.3%) successfully discontinued CRRT. The dynamic prediction by the XGBoost model produced an area under the curve of 0.848, with accuracy, sensitivity, and specificity of 0.782, 0.786, and 0.776, respectively. The performance of the XGBoost model was far superior to other test models. SHAP demonstrated that the features that contributed most to the model results were the Sequential Organ Failure Assessment score, serum lactate level, and 24-h urine output. CONCLUSION: Dynamic decision models supported by machine learning are capable of dealing with complex factors in CRRT and effectively predicting the outcome of discontinuation.


Assuntos
Injúria Renal Aguda , Terapia de Substituição Renal Contínua , Aprendizado de Máquina , Humanos , Terapia de Substituição Renal Contínua/métodos , Feminino , Masculino , Pessoa de Meia-Idade , Injúria Renal Aguda/terapia , Idoso , Unidades de Terapia Intensiva , Tomada de Decisão Clínica , Algoritmos , Terapia de Substituição Renal/métodos
3.
Microcirculation ; 29(6-7): e12746, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-34897901

RESUMO

OBJECTIVE: To establish methods for providing a comprehensive and detailed description of the spatial distribution of the vascular networks, and to reveal the spatiotemporal pattern of the yolk sac membrane vascular network during the angiogenic procedure. METHODS: Addressing the limitations in the conventional local fractal analysis, an improved approach, named scanning average local fractal dimension, was proposed. This method was conducted on 6 high-resolution vascular images of the yolk sac membrane for 3 eggs at two stages (E3 and E4) to characterize the spatial distribution of the complexity of the vascular network. RESULTS: With the proposed method, the spatial distribution of the complexity of the yolk sac membrane vascular network was visualized. From E3 to E4, the local fractal dimension increased in 3 eggs, 1.80 ± 0.02 vs. 1.85 ± 0.02, 1.72 ± 0.03 vs. 1.83 ± 0.02, and 1.77 ± 0.03 vs. 1.82 ± 0.02, respectively. The mean local fractal dimension in the most distal area from the embryo proper was the lowest at E3 while the highest at E4. At E3, the most peaks of the local fractal dimension were located in the vein territories and shifted to artery territories at E4. CONCLUSIONS: The spatial distribution of the complexity of the yolk sac membrane vascular network exhibited diverse patterns at different stages. In addition from E3 to E4, the increment of complexity at the intersection areas between arteries and sinus terminalis was with the most advance. This is consistent with the physiologic evidence. The present work provides a potential approach for investigating the spatiotemporal pattern of the angiogenic process.


Assuntos
Fractais , Saco Vitelino , Saco Vitelino/irrigação sanguínea , Artérias
4.
Microvasc Res ; 139: 104259, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34624307

RESUMO

Blood flow pulsatility is an important determinant of macro- and microvascular physiology. Pulsatility is damped largely in the microcirculation, but the characteristics of this damping and the factors that regulate it have not been fully elucidated yet. Applying computational approaches to real microvascular network geometry, we examined the pattern of pulsatility damping and the role of potential damping factors, including pulse frequency, vascular viscous resistance, vascular compliance, viscoelastic behavior of the vessel wall, and wave propagation and reflection. To this end, three full rat mesenteric vascular networks were reconstructed from intravital microscopic recordings, a one-dimensional (1D) model was used to reproduce pulsatile properties within the network, and potential damping factors were examined by sensitivity analysis. Results demonstrate that blood flow pulsatility is predominantly damped at the arteriolar side and remains at a low level at the venular side. Damping was sensitive to pulse frequency, vascular viscous resistance and vascular compliance, whereas viscoelasticity of the vessel wall or wave propagation and reflection contributed little to pulsatility damping. The present results contribute to our understanding of mechanical forces and their regulation in the microcirculation.


Assuntos
Arteríolas/fisiologia , Mesentério/irrigação sanguínea , Microcirculação , Modelos Cardiovasculares , Fluxo Pulsátil , Circulação Esplâncnica , Vênulas/fisiologia , Animais , Microscopia Intravital , Masculino , Ratos Wistar , Estresse Mecânico , Fatores de Tempo , Resistência Vascular
5.
Microvasc Res ; 134: 104101, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33166577

RESUMO

The hemodynamic conditions and partial pressure of oxygen in microcirculation generally indicate the status of tissue perfusion, which provides essential information for the assessment and treatment of critical diseases such as sepsis. The human tongue is known to have abundant microcirculation and is an ideal window to observe the microcirculation. At present, the monitoring of sublingual microcirculation is mostly achieved using handheld vital microscopy (HVM). Microcirculation is organized and works as a network. However, HVM can obtain only limited view of few vessels and is not able to acquire information regarding the entire network. In this work, we proposed a method to construct a mathematical network model of sublingual microcirculation to solve the problems. The proposed method is based on fractal analysis to model and simulate the hemodynamic and functional activities of sublingual microcirculation. Specifically, the HVM technology is used to obtain the partial morphological and hemodynamic data of sublingual microcirculation, and fractal analysis is applied thereafter to establish the hemodynamic model of the network based on the data from few vessels. Further, the adaptive regulation mechanism of microcirculation is introduced to enhance the performance of the model. The model was validated by the experimental data and the results are consistent with the characteristics of microcirculation. The work demonstrates the potential of the proposed method in sublingual microcirculation research and for the further assessment of tissue perfusion.


Assuntos
Fractais , Hemodinâmica , Microcirculação , Microvasos/fisiologia , Modelos Cardiovasculares , Língua/irrigação sanguínea , Adaptação Fisiológica , Adulto , Idoso de 80 Anos ou mais , Velocidade do Fluxo Sanguíneo , Simulação por Computador , Feminino , Humanos , Microscopia Intravital , Masculino , Microscopia de Vídeo , Pessoa de Meia-Idade , Fluxo Sanguíneo Regional , Fatores de Tempo
6.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 37(1): 1-9, 2020 Feb 25.
Artigo em Zh | MEDLINE | ID: mdl-32096371

RESUMO

Aiming at the problem that the small samples of critical disease in clinic may lead to prognostic models with poor performance of overfitting, large prediction error and instability, the long short-term memory transferring algorithm (transLSTM) was proposed. Based on the idea of transfer learning, the algorithm leverages the correlation between diseases to transfer information of different disease prognostic models, constructs the effictive model of target disease of small samples with the aid of large data of related diseases, hence improves the prediction performance and reduces the requirement for target training sample quantity. The transLSTM algorithm firstly uses the related disease samples to pretrain partial model parameters, and then further adjusts the whole network with the target training samples. The testing results on MIMIC-Ⅲ database showed that compared with traditional LSTM classification algorithm, the transLSTM algorithm had 0.02-0.07 higher AUROC and 0.05-0.14 larger AUPRC, while its number of training iterations was only 39%-64% of the traditional algorithm. The results of application on sepsis revealed that the transLSTM model of only 100 training samples had comparable mortality prediction performance to the traditional model of 250 training samples. In small sample situations, the transLSTM algorithm has significant advantages with higher prediciton accuracy and faster training speed. It realizes the application of transfer learning in the prognostic model of critical disease with small samples.


Assuntos
Algoritmos , Doença , Aprendizado de Máquina , Prognóstico , Humanos , Modelos Teóricos
7.
Microvasc Res ; 125: 103882, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31075242

RESUMO

Fractal dimension is a robust fractal parameter for estimating the morphology of vascular networks. It reflects the property of vascular networks that may vary and thus, differentiate between individual networks and/or identify physiological and pathological conditions. As such, fractal dimension differs also between arteriolar and venular compartments, yet the underlying reason is so far unclear. In order to understand the mechanisms behind these differences, we quantitatively analyzed the impacts of vessel attributes on the fractal dimension. Fractal dimension and vessel attributes given by vessel density (VD), vessel length density (VL), and diameter index (DI=VD/VL) were analyzed in three microvascular networks of the rat mesentery, which were reconstructed from experimental data. The results show that differences in diameter between arterioles and venules are primarily responsible for arterio-venous differences in fractal dimension. Moreover, multiple linear regression analysis demonstrates that the sensitivity of the variation of fractal dimension to vessel length and diameter varies with the type of the vessels. While the change of vessel length contributes 57.8 ±â€¯3.4% to the variation of arteriolar dimension, vessel diameter contributes 63.9 ±â€¯4.8% to the variation of venular dimension. The present study provides an explanation for the different fractal dimension and dimension variation in arteriolar and venular compartments. It highlights the importance of estimating the fractal dimensions of arterioles and venules separately, which will enhance the ability of feature extraction by fractal analysis in physiological and clinical application.


Assuntos
Arteríolas/anatomia & histologia , Fractais , Processamento de Imagem Assistida por Computador , Mesentério/irrigação sanguínea , Microscopia de Vídeo , Fotografação , Vênulas/anatomia & histologia , Animais , Valor Preditivo dos Testes , Ratos
8.
Microcirculation ; 25(5): e12458, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29729094

RESUMO

OBJECTIVE: PWV is the speed of pulse wave propagation through the circulatory system. mPWV emerges as a novel indicator of hypertension, yet it remains unclear how different vascular properties affect mPWV. We aim to identify the biomechanical determinants of mPWV. METHODS: A 1D model was used to simulate PWV in a rat mesenteric microvascular network and, for comparison, in a human macrovascular arterial network. Sensitivity analysis was performed to assess the relationship between PWV and vascular compliance and resistance. RESULTS: The 1D model enabled adequate simulation of PWV in both micro- and macrovascular networks. Simulated arterial PWV changed as a function of vascular compliance but not resistance, in that arterial PWV varied at a rate of 0.30 m/s and -6.18 × 10-3  m/s per 10% increase in vascular compliance and resistance, respectively. In contrast, mPWV depended on both vascular compliance and resistance, as it varied at a rate of 2.79 and -2.64 cm/s per 10% increase in the respective parameters. CONCLUSIONS: The present study identifies vascular compliance and resistance in microvascular networks as critical determinants of mPWV. We anticipate that mPWV can be utilized as an effective indicator for the assessment of microvascular biomechanical properties.


Assuntos
Microcirculação/fisiologia , Análise de Onda de Pulso , Resistência Vascular/fisiologia , Animais , Fenômenos Biomecânicos , Complacência (Medida de Distensibilidade)/fisiologia , Biologia Computacional , Humanos , Modelos Teóricos , Ratos , Circulação Esplâncnica
9.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 35(1): 45-48, 2018 02 25.
Artigo em Zh | MEDLINE | ID: mdl-29745599

RESUMO

Due to the decline of motor ability and the impact of the diseases, abnormalities in gait is common in the elderly population, which will raise the risk of fall and cause serious injury. This study focuses on the analysis of the gait kinematics parameters of normal adults' gait, aiming to investigate the characteristics of gait parameters in different age groups and to explore the role of gait parameters in motor function assessment and clinical diagnosis. Based on the gait data gained by electronic walkway, the relationship among the toe out angles and their correlation with age and gender etc. were quantitatively analyzed. The results show that most normal subjects walk with positive toe out angles, and the angles increase with age. Such changes are slow in the young and middle age groups. However, the elevations of the left out toe angle and the angles between the feet are statistically significant after entering elder age ( >60 years). The results also suggest that the angle between the feet is a kind of practical gait parameter for varying applications. This study concludes that feet angle analysis is potential to provide a convenient and quantitative tool for the assessment of lower limb motor ability and the diagnosis of knee joint diseases.

10.
Microvasc Res ; 113: 40-49, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28478072

RESUMO

Hemodynamic pulsatility has been reported to regulate microcirculatory function. To quantitatively assess the impact of flow pulsatility on the microvasculature, a mathematical model was first developed to simulate the regulation of NO production by pulsatile flow in the microcirculation. Shear stress and pressure pulsatility were selected as regulators of endothelial NO production and NO-dependent vessel dilation as feedback to control microvascular hemodynamics. The model was then applied to a real microvascular network of the rat mesentery consisting of 546 microvessels. As compared to steady flow conditions, pulsatile flow increased the average NO concentration in arterioles from 256.8±93.1nM to 274.8±101.1nM (P<0.001), with a corresponding increase in vessel dilation by approximately 7% from 27.5±10.6% to 29.4±11.4% (P<0.001). In contrast, NO concentration and vessel size showed a far lesser increase (about 1.7%) in venules under pulsatile flow as compared to steady flow conditions. Network perfusion and flow heterogeneity were improved under pulsatile flow conditions, and vasodilation within the network was more sensitive to heart rate changes than pulse pressure amplitude. The proposed model simulates the role of flow pulsatility in the regulation of a complex microvascular network in terms of NO concentration and hemodynamics under varied physiological conditions.


Assuntos
Mecanotransdução Celular , Mesentério/irrigação sanguínea , Microcirculação , Microvasos/metabolismo , Modelos Cardiovasculares , Óxido Nítrico/metabolismo , Fluxo Pulsátil , Animais , Simulação por Computador , Análise Numérica Assistida por Computador , Ratos , Estresse Mecânico , Fatores de Tempo , Vasodilatação
11.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 34(5): 784-789, 2017 Aug 01.
Artigo em Zh | MEDLINE | ID: mdl-29761967

RESUMO

The vessels in the microcirculation keep adjusting their structure to meet the functional requirements of the different tissues. A previously developed theoretical model can reproduce the process of vascular structural adaptation to help the study of the microcirculatory physiology. However, until now, such model lacks the appropriate methods for its parameter settings with subsequent limitation of further applications. This study proposed an improved quantum-behaved particle swarm optimization (QPSO) algorithm for setting the parameter values in this model. The optimization was performed on a real mesenteric microvascular network of rat. The results showed that the improved QPSO was superior to the standard particle swarm optimization, the standard QPSO and the previously reported Downhill algorithm. We conclude that the improved QPSO leads to a better agreement between mathematical simulation and animal experiment, rendering the model more reliable in future physiological studies.

12.
Zhongguo Yi Liao Qi Xie Za Zhi ; 39(4): 253-6, 2015 Jul.
Artigo em Zh | MEDLINE | ID: mdl-26665943

RESUMO

To solve the problem that mostly gait analysis is independent from the treatment, this work proposes a system that integrates the functions of gait training and assessment for foot drop treatment. The system uses a set of sensors to collect gait parameters and designes multi-mode functional electrical stimulators as actuator. Body area network technology is introduced to coordinate the data communication and execution of the sensors and stimulators, synchronize the gait analysis and foot drop treatment. Bluetooth 4.0 is applied to low the power consumption of the system. The system realizes the synchronization of treatment and gait analysis. It is able to acquire and analyze the dynamic parameters of ankle, knee and hip in real-time, and treat patients by guiding functional electrical stimulation delivery to the specific body locations of patients.


Assuntos
Estimulação Elétrica , Marcha , Terapia por Estimulação Elétrica , Terapia por Exercício , Humanos , Tecnologia sem Fio
13.
J Biomech Eng ; 136(1): 011009, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24190506

RESUMO

Techniques that model microvascular hemodynamics have been developed for decades. While the physiological significance of pressure pulsatility is acknowledged, most of the microcirculatory models use steady flow approaches. To theoretically study the extent and transmission of pulsatility in microcirculation, dynamic models need to be developed. In this paper, we present a one-dimensional model to describe the dynamic behavior of microvascular blood flow. The model is applied to a microvascular network from a rat mesentery. Intravital microscopy was used to record the morphology and flow velocities in individual vessel segments, and boundaries are defined according to the experimental data. The system of governing equations constituting the model is solved numerically using the discontinuous Galerkin method. An implicit integration scheme is adopted to increase computing efficiency. The model allows the simulation of the dynamic properties of blood flow in microcirculatory networks, including the pressure pulsatility (quantified by a pulsatility index) and pulse wave velocity (PWV). From the main input arteriole to the main output venule, the pulsatility index decreases by 66.7%. PWV obtained along arterioles declines with decreasing diameters, with mean values of 77.16, 25.31, and 8.30 cm/s for diameters of 26.84, 17.46, and 13.33 µm, respectively. These results suggest that the 1D model developed is able to simulate the characteristics of pressure pulsatility and wave propagation in complex microvascular networks.


Assuntos
Microcirculação/fisiologia , Microvasos/fisiologia , Modelos Cardiovasculares , Animais , Arteríolas/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Hemodinâmica , Masculino , Fluxo Pulsátil/fisiologia , Ratos , Ratos Wistar , Reologia , Vênulas/fisiologia
14.
Med Biol Eng Comput ; 62(4): 1061-1076, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38141104

RESUMO

Early detection of falls is important for reducing fall injuries. However, existing fall detection strategies mostly focus on reducing impact injuries rather than avoiding falls. This study proposed the concept of identifying "Imbalance Point" to warn the body imbalance, allowing sufficient time to recover balance. And if falling cannot be avoided, an impact sign is released by detecting the "Fall Point" prior to the impact. To achieve this goal, motion prediction model and balance recovery model are integrated into a spatiotemporal framework to analyze dynamic and kinematic features of body motion. Eight healthy young volunteers participated in three sets of experiment: Normal trial, Recovery trial and Fall trial. The body motion in the trials was recorded using Microsoft Azure Kinect. The results show that the developed algorithm for Fall Point detection achieved 100% sensitivity and 98.6% specificity, along with an average lead time of 297 ms. Moreover, Imbalance Point was successfully detected in all Fall trials, and the average time interval between Imbalance Point and Fall Point was 315 ms, longer than reported step reaction time for elderly (approximately 270 ms). The experiment results demonstrate that the developed algorithm have great potential for fall warning and protection in the elderly.


Assuntos
Algoritmos , Humanos , Idoso , Movimento (Física) , Fenômenos Biomecânicos , Voluntários Saudáveis
15.
Artif Intell Med ; 147: 102746, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38184353

RESUMO

BACKGROUND: Sepsis is a syndrome involving multi-organ dysfunction, and the mortality in sepsis patients correlates with the number of lesioned organs. Precise prognosis models play a pivotal role in enabling healthcare practitioners to administer timely and accurate interventions for sepsis, thereby augmenting patient outcomes. Nevertheless, the majority of available models consider the overall physiological attributes of patients, overlooking the asynchronous spatiotemporal interactions among multiple organ systems. These constraints hinder a full application of such models, particularly when dealing with limited clinical data. To surmount these challenges, a comprehensive model, denoted as recurrent Graph Attention Network-multi Gated Recurrent Unit (rGAT-mGRU), was proposed. Taking into account the intricate spatiotemporal interactions among multiple organ systems, the model predicted in-hospital mortality of sepsis using data collected within the 48-hour period post-diagnosis. MATERIAL AND METHODS: Multiple parallel GRU sub-models were formulated to investigate the temporal physiological variations of single organ systems. Meanwhile, a GAT structure featuring a memory unit was constructed to capture spatiotemporal connections among multi-organ systems. Additionally, an attention-injection mechanism was employed to govern the data flowing within the network pertaining to multi-organ systems. The proposed model underwent training and testing using a dataset of 10,181 sepsis cases extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. To evaluate the model's superiority, it was compared with the existing common baseline models. Furthermore, ablation experiments were designed to elucidate the rationale and robustness of the proposed model. RESULTS: Compared with the baseline models for predicting mortality of sepsis, the rGAT-mGRU model demonstrated the largest area under the receiver operating characteristic curve (AUROC) of 0.8777 ± 0.0039 and the maximum area under the precision-recall curve (AUPRC) of 0.5818 ± 0.0071, with sensitivity of 0.8358 ± 0.0302 and specificity of 0.7727 ± 0.0229, respectively. The proposed model was capable of delineating the varying contribution of the involved organ systems at distinct moments, as specifically illustrated by the attention weights. Furthermore, it exhibited consistent performance even in the face of limited clinical data. CONCLUSION: The rGAT-mGRU model has the potential to indicate sepsis prognosis by extracting the dynamic spatiotemporal interplay information inherent in multi-organ systems during critical diseases, thereby providing clinicians with auxiliary decision-making support.


Assuntos
Sepse , Humanos , Sepse/diagnóstico , Área Sob a Curva , Cuidados Críticos , Bases de Dados Factuais , Curva ROC
16.
J Am Coll Emerg Physicians Open ; 5(3): e13190, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38827500

RESUMO

Objective: To analyze the risk factors associated with intubated critically ill patients in the emergency department (ED) and develop a prediction model by machine learning algorithms. Methods: This study was conducted in an academic tertiary hospital in Hangzhou, China. Critically ill patients admitted to the ED were retrospectively analyzed from May 2018 to July 2022. The demographic characteristics, distribution of organ dysfunction, parameters for different organs' examination, and status of mechanical ventilation were recorded. These patients were assigned to the intubation and non-intubation groups according to ventilation support. We used the eXtreme Gradient Boosting (XGBoost) algorithm to develop the prediction model and compared it with other algorithms, such as logistic regression, artificial neural network, and random forest. SHapley Additive exPlanations was used to analyze the risk factors of intubated critically ill patients in the ED. Results: Of 14,589 critically ill patients, 10,212 comprised the training group and 4377 comprised the test group; 2289 intubated patients were obtained from the electronic medical records. The mean age, mean scores of vital signs, parameters of different organs, and blood oxygen examination results differed significantly between the two groups (p < 0.05). The white blood cell count, international normalized ratio, respiratory rate, and pH are the top four risk factors for intubation in critically ill patients. Based on the risk factors in different predictive models, the XGBoost model showed the highest area under the receiver operating characteristic curve (0.84) for predicting ED intubation. Conclusions: For critically ill patients in the ED, the proposed model can predict potential intubation based on the risk factors in the clinically predictive model.

17.
Zhonghua Nei Ke Za Zhi ; 52(3): 181-4, 2013 Mar.
Artigo em Zh | MEDLINE | ID: mdl-23856105

RESUMO

OBJECTIVE: To investigate the association between body mass index (BMI) and exercise capacity in patients with chronic systolic heart failure. METHODS: The elderly patients with chronic systolic heart failure were consecutively recruited from 2008 to 2011 in cardiovascular clinic of Zhejiang Hospital. All the participants underwent height and weight measurements and BMI was calculated with these two parameters. Cardiopulmonary exercise test were performed to achieve peak oxygen uptake (PVO(2)), oxygen uptake to body mass ratio (PKVO(2)), oxygen uptake to heart ratio (VO(2)/HR) and ventilation/carbon dioxide production (VO(2)/VCO(2)). RESULTS: A total of the 273 patients with chronic systolic heart failure included 6 underweight patients (BMI < 18.5 kg/m(2)), 113 normal weight patients (BMI 18.5 - < 24.0 kg/m(2)), 116 overweight patients (BMI 24.0 - < 28.0 kg/m(2)), and 38 obese patients (BMI ≥ 28 kg/m(2)). In both NYHA II and III/IV patients, unadjusted correlation analyses showed that BMI was positively related to PVO(2) and VO(2)/HR, and was inversely related to PKVO(2) and VE/VCO(2) (P < 0.05), respectively. Multiple stepwise regression analyses showed age, sex, BMI (P < 0.05) and left ventricular ejection fraction (LVEF) were independent determinants of PKVO(2), and age and BMI (P < 0.05) were independent determinants of VE/VCO(2). CONCLUSIONS: BMI is significantly associated with exercise capacity in patients with chronic systolic heart failure, and also independent determinant for the PKVO(2) and VE/VCO(2), respectively.


Assuntos
Índice de Massa Corporal , Tolerância ao Exercício , Insuficiência Cardíaca Sistólica , Idoso , Idoso de 80 Anos ou mais , Doença Crônica , Feminino , Humanos , Masculino
18.
Comput Biol Med ; 153: 106459, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36603435

RESUMO

BACKGROUND AND OBJECTIVE: Despite the numerous studies on extubation readiness assessment for patients who are invasively ventilated in the intensive care unit, a 10-15% extubation failure rate persists. Although breathing variability has been proposed as a potential predictor of extubation failure, it is mainly assessed using simple statistical metrics applied to basic respiratory parameters. Therefore, the complex pattern of breathing variability conveyed by continuous ventilation waveforms may be underexplored. METHODS: Here, we aimed to develop novel breathing variability indices to predict extubation failure among invasively ventilated patients. First, breath-to-breath basic and comprehensive respiratory parameters were computed from continuous ventilation waveforms 1 h before extubation. Subsequently, the basic and advanced variability methods were applied to the respiratory parameter sequences to derive comprehensive breathing variability indices, and their role in predicting extubation failure was assessed. Finally, after reducing the feature dimensionality using the forward search method, the combined effect of the indices was evaluated by inputting them into the machine learning models, including logistic regression, random forest, support vector machine, and eXtreme Gradient Boosting (XGBoost). RESULTS: The coefficient of variation of the dynamic mechanical power per breath (CV-MPd[J/breath]) exhibited the highest area under the receiver operating characteristic curve (AUC) of 0.777 among the individual indices. Furthermore, the XGBoost model obtained the best AUC (0.902) by combining multiple selected variability indices. CONCLUSIONS: These results suggest that the proposed novel breathing variability indices can improve extubation failure prediction in invasively ventilated patients.


Assuntos
Respiração Artificial , Desmame do Respirador , Humanos , Desmame do Respirador/métodos , Extubação , Estudos Prospectivos , Respiração
19.
Comput Methods Biomech Biomed Engin ; 26(9): 1044-1054, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35903012

RESUMO

Margin of stability (MOS) is one of the essential indices for evaluating dynamic stability. However, there are indications that MOS was affected by body height and its application in identifying factors on dynamic stability other than body height is restricted. An inverted pendulum model was used to simulate human walking and investigate the relevance between MOS and body height. Eventually, a height-independent index in dynamic stability assessment (named as Angled Margin of Stability, AMOS) was proposed. For testing, fifteen healthy young volunteers performed walking trials with normal arm swing, holding arms, and anti-normal arm swing. Kinematic parameters were recorded using a gait analysis system with a Microsoft Kinect V2.0 and instrumented walkway. Both simulation and test results show that MOS had a significant correlation with height during walking with normal arm swing, while AMOS had no such significant correlation. Walking with normal arm swing produced significantly larger AMOS than holding arms and anti-normal arm swing. However, no significant difference showed up in MOS between normal arm swing and holding arms. The results suggest that AMOS is not affected by body height and has the potential to identify the variations in dynamic stability caused by physiological factors other than body height.


Assuntos
Estatura , Marcha , Humanos , Marcha/fisiologia , Caminhada/fisiologia , Braço/fisiologia , Simulação por Computador , Fenômenos Biomecânicos/fisiologia
20.
IEEE J Biomed Health Inform ; 27(8): 4120-4130, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37159312

RESUMO

Noninvasive ventilation (NIV) has been recognized as a first-line treatment for respiratory failure in patients with chronic obstructive pulmonary disease (COPD) and hypercapnia respiratory failure, which can reduce mortality and burden of intubation. However, during the long-term NIV process, failure to respond to NIV may cause overtreatment or delayed intubation, which is associated with increased mortality or costs. Optimal strategies for switching regime in the course of NIV treatment remain to be explored.For the goal of reducing 28-day mortality of the patients undergoing NIV, Double Dueling Deep Q Network (D3QN) of offline-reinforcement learning algorithm was adopted to develop an optimal regime model for making treatment decisions of discontinuing ventilation, continuing NIV, or intubation. The model was trained and tested using the data from Multi-Parameter Intelligent Monitoring in Intensive Care III (MIMIC-III) and evaluated by the practical strategies. Furthermore, the applicability of the model in majority disease subgroups (Catalogued by International Classification of Diseases, ICD) was investigated. Compared with physician's strategies, the proposed model achieved a higher expected return score (4.25 vs. 2.68) and its recommended treatments reduced the expected mortality from 27.82% to 25.44% in all NIV cases. In particular, for these patients finally received intubation in practice, if the model also supported the regime, it would warn of switching to intubation 13.36 hours earlier than clinicians (8.64 vs. 22 hours after the NIV treatment), granting a 21.7% reduction in estimated mortality. In addition, the model was applicable across various disease groups with distinguished achievement in dealing with respiratory disorders. The proposed model is promising to dynamically provide personalized optimal NIV switching regime for patients undergoing NIV with the potential of improving treatment outcomes.


Assuntos
Ventilação não Invasiva , Doença Pulmonar Obstrutiva Crônica , Insuficiência Respiratória , Humanos , Ventilação não Invasiva/efeitos adversos , Insuficiência Respiratória/terapia , Insuficiência Respiratória/etiologia , Resultado do Tratamento , Cuidados Críticos , Doença Pulmonar Obstrutiva Crônica/terapia , Políticas
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