Utilidad de la tomografía de impedancia eléctrica para la programación del ventilador mecánico en paciente crítico pediátrico, una alternativa dinámica y no invasiva: revisión de dos casos clínicos / Utility of electrical impedance tomography for mechanical ventilator programming in pediatric critical patients, a dynamic and non-invasive alternative: a review of two clinical cases

La tomografía por impedancia eléctrica (TIE) es una modalidad de monitorización funcional respiratoria por imagen, no invasiva y libre de radiación, que permite visualizar en tiempo real la ventilación pulmonar regional y global en pacientes adultos y pediátricos conectados a Ventilación Mecánica (VM). OBJETIVO: Se describe la utilidad de la TIE en dos pacientes críticos pediátricos, en quienes no fue factible realizar medición de mecánica pulmonar, como herramienta para el ajuste de parámetros ventilatorios. CASOS CLÍNICOS: Se presentan dos pacientes pediátricos de 27 y 11 meses con condiciones clínicas diferentes, conectados a VM, en quienes se utilizó la TIE como método de monitoreo de la distribución pulmonar y titulación de la presión positiva al final de la espiración (PEEP) óptima, con el objetivo de obtener una ventilación pulmonar más homogénea. Se presentan mediciones funcionales con diferentes niveles de PEEP y valores de distribución en las distintas regiones de interés (ROI), además de un flujograma de situaciones en las que la TIE podría resultar útil para el ajuste ventilatorio. CONCLUSIÓN: La información funcional proporcionada por la TIE, permitió monitorizar de forma dinámica la VM y optimizar los parámetros ventilatorios, facilitando la implementación de estrategias de protección pulmonar en ambos pacientes, imposibilitados de realizar una medición estática de la mecánica respiratoria.

The Electrical Impedance Tomography (EIT) is a non-invasive and radiation-free respiratory functional imaging monitoring modality that allows real-time visualization of regional and global lung ventilation in adult and pediatric patients connected to mechanical ventilation (MV). OBJECTIVE: This paper describes the utility of EIT in two critical pediatric patients for whom measuring pulmonary mechanics was not feasible. EIT is used as a tool for adjusting ventilatory parameters. CLINICAL CASES: Two pediatric patients aged 27 and 11 months, with different clinical conditions, connected to MV are presented. EIT was used to monitor lung distribution and titrate the optimal Positive End-Expiratory Pressure (PEEP), to achieve more homogeneous lung ventilation. Functional measurements are presented with different PEEP levels and distribution values in different regions of interest (ROI), along with a flowchart illustrating situations where EIT could be useful for ventilatory adjustment. CONCLUSION: The functional information provided by EIT, allowed dynamic monitoring of MV, optimizing ventilatory parameters and facilitating the implementation of lung protective strategies in both patients, unable to undergo static respiratory mechanics measurements.

Pulmonary strain and end-expiratory lung volume during apnea test: a comparative analysis using electrical impedance tomography / Stress pulmonar y volumen pulmonar de fin de es piración durante el test de apnea: estudio compara tivo utilizando tomografía por impedancia eléctrica

Abstract The apnea test, employed for brain death assessment, aims to demonstrate the absence of respiratory drive due to hypercapnia. The tracheal oxygen insufflation apnea test mode (I-AT) involves disconnecting the pa tient from invasive mechanical ventilation (iMV) for ap proximately 8 minutes while maintaining oxygenation. This test supports the diagnosis of brain death based on a specified increase in PaCO2. Common complications include hypoxemia and hemodynamic instability, and lung collapse-induced reduction in end-expiratory lung volume (EELV). In our case series utilizing electrical impedance to mography (EIT), we observed that continuous positive airway pressure during the apnea test (CPAP-AT) effec tively mitigated lung collapse. This resulted in improved pulmonary strain compared to the disconnection of iMV. These findings suggest the potential benefits of routine CPAP-AT, particularly for potential lung donors, emphasizing the relevance of our study in providing quantitative insights into EELV loss and its association with pulmonary strain and potential lung injury.

Resumen La prueba de apnea es una técnica diagnóstica am pliamente utilizada para la evaluación de la muerte cerebral, con el objetivo de demostrar la ausencia de impulso respiratorio debido a la hipercapnia. La variante de la prueba de apnea con insuflación de oxígeno traqueal (I-AT) implica desconectar al pacien te de la ventilación mecánica invasiva (iVM) durante aproximadamente 8 minutos, manteniendo la oxigena ción mediante un catéter de insuflación. Esta prueba respalda el diagnóstico de muerte cerebral cuando se determina un aumento de la PaCO2 superior a 20 mmHg en comparación con el valor inicial o un nivel de PaCO2 superior a 60 mmHg al final de la prueba. En nuestra serie de casos, la implementación de la tomografía de impedancia eléctrica (EIT) reveló que la prueba de apnea con presión positiva continua (CPAP-AT) mitiga eficazmente el colapso pulmonar. Este enfo que resulta en una mejora en la tensión pulmonar en comparación con la desconexión de iMV, demostrando su relevancia en el contexto de potenciales donantes de pulmones.

Pyloric EndoFlip and Its Clinical Use in Gastroparesis / EndoFLIP pilórico y su utilidad clínica en gastroparesia

Abstract Gastroparesis is a chronic disorder of gastric motility that results in marked impairment of quality of life and significant costs to health care systems. Medical therapies are limited in their management, thus, the reason for a growing enthusiasm for pylorus-targeted therapies. The functional luminal imaging probe (FLIP) is a useful diagnostic tool for assessing pylorus characteristics, especially in refractory cases, which could lead to a better management strategy and, in many cases, predict clinical response.

Resumen La gastroparesia es un trastorno crónico de la motilidad gástrica que genera un deterioro marcado de la calidad de vida y costos significativos en los sistemas de salud. Las terapias médicas son limitadas para su manejo, por lo cual ha surgido un entusiasmo creciente en las terapias dirigidas al píloro. La sonda de imagen luminal funcional (FLIP) ha demostrado ser una herramienta diagnóstica útil para evaluar las características del píloro, especialmente en casos refractarios, en los que podría guiar hacia una mejor estrategia de manejo y, en muchos casos, predecir la respuesta clínica.

A Sensor for Detection of Breast Tumor with Three-dimensional Electrical Impedance Tomography / 分析化学

An intensive breast array sensor was designed based on three-dimensional electrical impedance tomography in this work.Firstly,an electrical impedance sensor for detection of breast cancer was developed.The sensor adopted the integrated design of excitation electrode array and ground electrode to achieve structural simplification.It realized electric field densification through conical matrix and double-layer circumferentially arranged electrode array and improved the detection accuracy of target object through taper optimization.Secondly,the imaging system was designed,and the sensor was optimized by numerical simulation.The simulation results showed that halving the number of electrodes did not affect imaging accuracy of the sensor,but could improve the imaging speed.Finally,the performance of the sensor was verified by experiment.The signal-to-noise ratio and channel consistency of the system were at a good level.The sensor was used to reconstruct three-dimensional image of the experimental model with relative volume of the detection field of 0.4%.The image correlation coefficient of the single target imaging was above 0.6 and the position of the double target object could be clearly identified,and thus the visual detection of breast cancer was realized.

Research progress of electrical impedance tomography in positive end-expiratory pressure titration / 临床麻醉学杂志

Appropriate positive end-expiratory pressure(PEEP)level is an important component of protective lung ventilation strategy.PEEP can maintain the openness of alveoli and reduce lung collapse in-jury.Although individualized PEEP application has been increasingly recognized by clinical physicians,the optimal PEEP titration method is still controversial.Electrical impedance tomography(EIT)is a non-inva-sive and radiation-free imaging technique that can be used to dynamically assess lung function at the bedside.EIT presents changes in impedance during ventilation as dynamic images,which can reflect altera-tions in ventilation and gas distribution before and after PEEP adjustments.Therefore,EIT can be utilized to tailor individualized PEEP.This article provides a brief overview of the basic principles and monitoring pa-rameters of EIT.It elucidates the PEEP titration method under the guidance of EIT in clinical applications(PEEPEIT),aiming at enhancing the understanding of the advantages and limitations of EIT and providing reference for the setting of individualized PEEP.

Evaluation of Clinical Efficacy of Modified Houpo Dahuangtang in Moderate and Severe ARDS Patients Based on Electrical Impedance Tomography / 中国实验方剂学杂志

ObjectiveTo evaluate the clinical efficacy of modified Houpo Dahuangtang in moderate and severe acute respiratory distress syndrome （ARDS） patients with phlegm-heat accumulation，and monitor the pulmonary ventilation changes of patients before and after treatment by electrical impedance tomography（EIT）. MethodThe 62 cases of moderate and severe ARDS patients with phlegm-heat accumulation who required mechanical ventilation in the department of intensive care unit （ICU） in Chongqing Hospital of Traditional Chinese Medicine from September 2021 to June 2022 were selected，and divided into an experimental group（31 cases）and a control group（31 cases）using a random number table. On the basis of regular Western medicine treatment，the experimental group received modified Houpo Dahuangtang and the control group received warm water by a nasogastric tube for seven days. The changes in the clinical efficacy of traditional Chinese medicine（TCM），the oxygenation index［arterial oxygen partial pressure （PaO2）/fractional inspired oxygen（FiO2），P/F］，lactic acid（Lac），acute physiology and chronic health evaluation Ⅱ（APACHE Ⅱ） score，compliance，plateau pressure，gas distribution parameters monitored by EIT（Z1，Z2，Z3 and Z4），inflammatory factors［interleukin-6 （IL-6），IL-10， tumor necrosis factor-α （TNF-α） and C-reactive protein （CRP）］ of both groups before and after treatment were recorded. Besides， the mechanical ventilation time， length of stay in ICU， 28-day mortality and incidence of adverse reactions（delirium，abdominal pain and diarrhea）in the two groups were also observed. ResultThere was no significant difference in the baseline indexes of patients in the two groups，and thus the two groups were comparable. After treatment for one week， the total effective rate for TCM syndromes in the experimental group was 90.30%（28/31）， higher than the 67.74%（21/31）in the control group（Z=-2.415，P<0.05）.Compared with the same group before treatment， the plateau pressure and Lac decreased （P<0.01）and the compliance and P/F increased （P<0.01） in experimental group， while the Lac decreased （P<0.05）and the P/F increased （P<0.05）， and the compliance and plateau pressure did not change significantly in the control group. After treatment，the plateau pressure and inflammatory factors in the experimental group were lower than those in the control group（P<0.05）， but the compliance and P/F in the experimental group were higher than those in the control group（P<0.05）， and the gas distribution parameters Z1，Z2，Z3，Z4，Z1+Z2，and Z3+Z4 monitored by EIT in the experimental group were all higher than those in the control group （P<0.05）. There was no significant difference in mechanical ventilation time， ICU hospitalization time， 28-day mortality， delirium， abdominal pain， diarrhea and other adverse reactions between the two groups. ConclusionModified Houpo Dahuangtang can significantly improve the P/F，pulmonary ventilation in gravity-dependent regions and pulmonary compliance，reduce the release of inflammatory factors in moderate and severe ARDS patients. Compared with conventional methods，EIT can timely monitor the pulmonary ventilation changes in ARDS patients，which suggests its clinical feasibility.

Bioactive Determination of Anfibatide / 医药导报

Objective To screen and establish a method for determining the biological activity of anfibatide.Meth-ods Three methods of light transmittance aggregometry(LTA),whole blood electrical impedance aggregometry,and continuous platelet count method were compared and studied.And the constant platelet counting method was chosen and verified to detect the biological activity of anfibatide.Results The RSD values of anfibatide biological activity detected by LTA,whole blood electri-cal impedance aggregometry,and continuous platelet count method were 10.3%,14.0%,and 3.6%,respectively.RSD of repeat-ability of 6 parallel test articles was 11.0%.The RSD of intermediate precision of 12 test articles for different personnel was 9.8%,and the inhibition rate of anfibatide was linear in the range of 0.3-0.5 U.The correlation coefficient was more than 0.990.The ac-tivity of three batches of anfibatide was determined,and the inhibition rate was 49.9%～53.6%.Conclusion The continuous platelet count method for determining anfibatide activity was established and verified,which can be used for quality control for an-fibatide activity since the precision and detection limit of the method met the requirement for activity assay of biological products.

Physiological effect of high flow oxygen therapy measured by electrical impedance tomography in single-lung transplantation / Efectos fisiológicos del alto flujo de oxígeno medido por tomografía de impedancia eléctrica en trasplante unipulmonar

Abstract In patients with chronic obstructive pulmonary dis ease (COPD), single lung transplantation (SLT) is some times performed as an alternative to bilateral lung trans plantation due to limited organ availability. However, the postoperative management of SLT presents challenges, including complications related to the distinct compli ance of each lung. This case report presents the case of a 65-year-old male patient who underwent SLT and was in the weaning period from mechanical ventilation. High-flow oxygen therapy (HFOT) was administered, and the physiological effects were measured using electrical impedance tomography (EIT). The results demonstrated that the application of HFOT increased air trapping and overdistention in the native lung without benefiting the transplanted lung. HFOT through a tracheostomy tube or nasal cannula resulted in a more heterogeneous distri bution of ventilation, with increased end expiratory lung impedance, prolonged expiratory time constants, and an increase in silent spaces. The drop in tidal impedance after applying HFOT did not indicate hypoventilation but rather overdistention and air trapping in the native lung, while the transplanted lung showed evidence of hypoventilation. These findings suggest that HFOT may not be beneficial for SLT patients and could potentially worsen outcomes. However, due to the limited scope of this case report, further prospective studies with larger patient cohorts are needed to confirm these results.

Resumen En pacientes con enfermedad pulmonar obstructiva crónica (EPOC), el trasplante pulmonar unilateral (SLT, por sus siglas en inglés) se realiza como alternativa a la disponibilidad limitada de donantes para el trasplante pulmonar bilateral. Sin embargo, el manejo postoperato rio del SLT presenta desafíos, incluyendo complicaciones relacionadas con la distinta complacencia de cada pul món. Este reporte presenta el caso de un paciente varón de 65 años que fue sometido a un SLT y se encontraba en el proceso de destete de la ventilación mecánica. Se administró terapia de oxígeno de alto flujo (HFOT, por sus siglas en inglés) y se midieron los efectos fisiológicos utilizando la tomografía de impedancia eléctrica (EIT, por sus siglas en inglés). Los resultados demostraron que la aplicación de HFOT aumentó la retención de aire y la hiperinflación en el pulmón nativo sin beneficiar al pulmón trasplantado. Tanto la HFOT a través de un tubo de traqueostomía como a través de cánula nasal resultaron en una distribución más heterogénea de la ventilación, con un aumento en la impedancia pulmonar al final de la espiración, prolongación de las constantes de tiempo espiratorias y un aumento en los espacios silentes. La disminución de la impedancia tidal después de aplicar HFOT no indicó hipoventilación, sino más bien hiperinsuflación y retención de gas en el pulmón nativo, mientras que el pulmón trasplantado mostró evidencia de hipoventilación. Estos hallazgos sugieren que el HFOT puede no ser beneficioso para los pacientes con SLT y podría empeorar los resultados. Sin embargo, debido al alcance limitado de este informe de caso, se necesitan estudios prospectivos con cohortes de pacientes más amplias para confirmar estos resultados.

Monitorización avanzada durante la desvinculación de la ventilación mecánica invasiva en el trasplante unipulmonar / Advanced monitoring during weaning of invasive me chanical ventilation in single-lung transplantation

Resumen El trasplante de pulmón bilateral es el tratamiento de las enfermedades pulmonares en su etapa terminal. Sin embargo, a veces se realiza el trasplante de un solo pulmón. La técnica no está exenta de complicaciones como la hiperinsuflación aguda del pulmón nativo y cambios en el diafragma, predisponiendo a atelectasias e insuficiencia respiratoria que pueden derivar en resul tados negativos. Por lo tanto, las pruebas de respiración espontánea pueden fallar y retrasar el proceso de des vinculación de la ventilación mecánica. La combinación de herramientas de monitorización avanzadas, como la tomografía por impedancia eléctrica y la ecografía, para diagnosticar la causa de este fallo, reconociendo y cuantificando la distribución del volumen pulmonar y su comportamiento dinámico, podría ser crucial para mejorar los resultados. Presentamos el caso de un paciente con trasplante unipulmonar y ventilación prolongada que falla en repetidas ocasiones durante la desvinculación de la ventilación mecánica, donde utilizamos herramientas de monitoreo avanzado para detectar la causa de la falla.

Abstract Bilateral lung transplantation is the treatment of end-stage lung diseases. However, sometimes a single lung transplant is performed. The technique is not exempt from complications such as acute hyperinfla tion of the native lung and changes in the diaphragm, predisposing to atelectasis and respiratory failure that can lead to negative results. Therefore, spontaneous breathing trials may fail and delay the weaning process. The combination of advanced monitoring tools, such as electrical impedance tomography and ultrasonography, to diagnose the cause of this failure, recognizing and quantifying the distribution of lung volume and its dynamic behavior could be crucial to improve outcomes. We present the case of a patient with a one-lung transplant and prolonged mechanical ventilation who, after presenting successive failures in the weaning pro cess, underwent advanced monitoring in order to find the causes of the failure.

Associação entre força de preensão manual e ângulo de fase em idosos da Estratégia Saúde da Família: um estudo transversal / Association between handgrip strength and phase angle in older adults from the Family Health Strategy: a cross-sectional study

Introdução: a Força de Preensão Manual (FPM) é um indicador de saúde e funcionalidade do idoso, que diminui com o passar do tempo, impactada por aspectos como mudanças na composição corporal. Objetivo: investigar a associação entre o Ângulo de Fase Padronizado (AFP) e FPM em idosos comunitários da Atenção Primária à Saúde (APS). Metodologia: estudo transversal, com pessoas de 60 anos ou mais, atendidos na APS. A variável dependente foi a FPM medida com dinamômetro e a independente principal foi o AFP com base no sexo e faixa etária, calculado a partir do ângulo de fase obtido pela bioimpedância. Foi realizada a regressão logística com entrada por bloco, sendo incluídas no modelo as variáveis que apresentaram associação com nível crítico menor do que 10%. Resultados: dos 296 indivíduos avaliados, 28,0% exibiram baixa FPM e 15,9% apresentaram AFP < ­ 1,65°. As variáveis inseridas no modelo final de regressão logística, juntamente com o AFP, foram sexo, faixa etária, Índice de Massa Corporal (IMC) e Circunferência da Panturrilha (CP). A análise mostrou que o AFP < ­ 1,65° aumenta a chance do idoso apresentar baixa FPM, tanto na análise sem ajuste (OR = 2,71; IC 95% 1,43-5,15), quanto no modelo final (OR = 2,35; IC 95% 1,14-4,87). Conclusão: o AFP mostrou-se associado à FPM, independentemente da interação com sexo, faixa etária, IMC e CP. A sua utilização pode contribuir na avaliação de idosos, especialmente quando a aferição da FPM não for possível.

Introduction: Handgrip Strength (HGS) is an indicator of health and functionality of the older adults, which decreases over time, impacted by aspects including changes in body composition. Objective: to investigate the association between the Standardized Phase Angle (SPA ) and HGS in community-dwelling older adults in Primary Health Care (PHC). Methodology: cross-sectional study, with people aged 60 or over, assisted in the PHC. The dependent variable was the HGS measured using a dynamometer. The main independent variable was the SPA based on gender and age range, calculated from the phase angle obtained by bioimpedance. Block-by-block logistic regression was performed, including variables that were associated with a critical level lower than 10% in the model. Results: of the 296 individuals assessed, 28.0% had low HGS and 15.9% had SPA < ­ 1.65°. The variables inserted in the final logistic regression model, together with the SPA , were gender, age group, Body Mass Index (BMI) and Calf Circumference (CC). The analysis showed that SPA < ­ 1.65° increases the chance of the older adults having low HGS, both in the unadjusted analysis (OR = 2.71; 95% CI 1.43-5.15) and in the final model (OR = 2.35; 95%CI 1.14-4.87). Conclusion: the SPA was associated with HGS, regardless of the interaction with sex, age group, BMI and CC. Its use can contribute to the evaluation of the older adults, especially when HGS measurement is not possible.

Research progress on electrical impedance tomography in pulmonary perfusion / 生物医学工程学杂志

Electrical impedance tomography (EIT) is an emerging technology for real-time monitoring based on the impedance differences of different tissues and organs in the human body. It has been initially applied in clinical research as well as disease diagnosis and treatment. Lung perfusion refers to the blood flow perfusion function of lung tissue, and the occurrence and development of many diseases are closely related to lung perfusion. Therefore, real-time monitoring of lung perfusion is particularly important. The application and development of EIT further promote the monitoring of lung perfusion, and related research has made great progress. This article reviews the principles of EIT imaging, lung perfusion imaging methods, and their clinical applications in recent years, with the aim of providing assistance to clinical and scientific researchers.

Prediction method for weaning outcomes based on machine learning and electrical impedance tomography / 医疗卫生装备

Objective To propose a method for predicting weaning outcomes based on machine learning and electrical impedance tomography(EIT).Methods Firstly,EIT image features were extracted from a total of 84 samples from 30 patients,and the important features screened with the extreme gradient boosting(XGBoost)algorithm were used as inputs to the model.Secondly,the prediction model was built with six machine learning methods,namely random forest(RF),support vector machines(SVM),XGBoost,gradient boosting decision tree(GBDT),logistic regression(LR)and decision tree(tree).Then the prediction model had its prediction performance evaluated by AUC,accuracy,sensitivity and specificity under imbalanced dataset,over-sampling balanced dataset and random under-sampling balanced dataset.Results In terms of AUC,accuracy and specificity,the model under the over-sampling balanced dataset and the random under-sampling balanced dataset behaved better than that under the imbalanced dataset(P＜0.05);in terms of sensitivity,the difference in model performance between the over-sampling balanced dataset and the imbalanced dataset was not statistically significant(P＞0.05),and the model performance under the random under-sampling balanced dataset decreased when compared with that under the imbalanced dataset(P＜0.05).There were no significant differences between the model performance under the over-sampling balanced dataset and that under the random under-sampling balanced dataset(P＞0.05).The model based on XGBoost behaved the best under the over-sampling balanced dataset,with an AUC of 0.769,an accuracy of 0.808,a sensitivity of 0.938 and a specificity of 0.600.Conclusion The method based on machine learning and EIT predicts weaning outcomes of patients with prolonged mechanical ventilation,and thus can be used for auxiliary decision support for clinicians to determine the appropriate timing of weaning.[Chinese Medical Equipment Journal,2023,44(10):1-6]

Vaginal Electrical Impedance Detects the Fertile Window in Healthy Women: a Pilot Study / La Impedancia Eléctrica Vaginal Detecta la Ventana Fértil en Mujeres Sanas: un Estudio Piloto

ABSTRACT This work analyzes the electrical impedance (EI) measurement of cervical mucus (CM) using a device to determine the fertile window. In this prospective and longitudinal study, fourteen healthy women aged 18 to 44 were enrolled to evaluate three menstrual cycles. EI was measured through a medical device inserted into the vagina for two minutes daily. Patients were monitored by urine luteinizing hormone (LH) strip, blood collection, and vaginal ultrasound to visualize the dominant follicle. Finally, the predictive EI capacity was validated by the receiver operating characteristic (ROC) of anovulatory vs. ovulatory impedances. The peak of LH was 35.7 (±4.5) mUI/ml and the dominant follicle size was 15.45 mm (±0.559). There were statistical differences in EI measurements between the follicular and luteal phases vs. the ovulation phase (p<0.0361 and p<0.0160). After data normalization, an area under the ROC curve (AUC) of 0.713 (P value= 0.0253), a Youden J index of 0.4545Ω, a sensitivity of 63.6%, and a specificity of 81.8% were found. Low EI in the ovulatory period belongs to the LH ovulatory peak and follicular release. EI can be used for ovulation monitoring, birth control, or promoting pregnancy as a safe and innocuous method.

RESUMEN Este trabajo analiza la medición de la impedancia eléctrica (IE) del moco cervical (MC) mediante un dispositivo para determinar la ventana fértil. En este estudio prospectivo y longitudinal, se incluyeron 14 mujeres sanas de 18 a 44 años para evaluar tres ciclos menstruales. La IE se midió a través de un dispositivo médico colocado en la vagina durante dos minutos diarios. Las pacientes fueron monitoreadas con una tira de hormona luteinizante (LH) en orina, recolección de sangre y ultrasonido vaginal para visualizar el folículo dominante. Finalmente, la capacidad predictiva de IE fue validada por la curva ROC (receiver operating characteristic) de impedancias anovulatorias vs. ovulatorias. El pico de LH fue de 35.7(±4.5) mUI/ml; el folículo de tamaño dominante fue de 15.45 mm (±0.559). Se encontraron diferencias estadísticas para la medición de la IE de las fases folicular y lútea versus la fase de ovulación (p<0.0361 y p<0.0160). Después de la normalización de los datos, se encontró un área bajo la curva ROC (AUC) de 0.713 (valor de P = 0.0253), un índice de Youden J de 0.4545 Ω, sensibilidad del 63.6 % y especificidad del 81.8 %. La IE baja en el período ovulatorio que pertenece al pico ovulatorio de LH y liberación folicular. La IE se puede utilizar para el control de la ovulación, el control de la natalidad o la promoción del embarazo como método seguro e inocuo.

Electrical Impedance Tomography to Measure Spirometry Parameters in Chronic Obstructive Pulmonary Disease Patients / Tomografía por Impedancia Eléctrica para Medir Parámetros de Espirometría en Pacientes con Enfermedad Pulmonar Obstructiva Crónica

ABSTRACT Spirometry is a test for the diagnosis of chronic obstructive pulmonary disease. It is a technique that can be intolerant due to the essential use of a mouthpiece and a clamp. This study proposes the use of electrical impedance tomogra phy to measure respiratory parameters. Patients underwent spirometry and three respiratory exercises. The imped ance signals were convolved, and the resultant was analyzed by fast Fourier transform. The frequency spectrum was divided into seven segments (R1 to R7). Each segment was represented in terms of quartiles (Q25%, Q50%, Q75%). Each quartile of each segment was correlated with the spirometric parameters to obtain a fitting equation. FVC was correlated 70% with the 3 quartiles of R7, 3 equations were obtained with a fit of 60%. FEV1 correlated 70% with the Q50% of R7, obtaining an equation with a fit of 40%. FEV1/FVC correlated 69% with Q75% of R2, obtaining an equation with a fit of 60%. Spirometric parameters can be estimated from the implied carrier frequency components of the ventilatory impedance signal.

RESUMEN La espirometría es una prueba para el diagnóstico de enfermedad pulmonar obstructiva crónica. Es una técnica que puede resultar intolerante debido al uso imprescindible de una boquilla y una de pinza. Este estudio propone el uso de la tomografía de impedancia eléctrica para medir los parámetros respiratorios. Los pacientes realizaron una espi rometría y tres ejercicios respiratorios. Las señales de impedancia fueron convolucionadas, y la resultante se analizó mediante una transformada rápida de Fourier. El espectro en frecuencias se dividió en siete segmentos (R1 a R7). Cada segmento se representó en términos de cuartiles (Q25%, Q50%, Q75%). Cada cuartil de cada segmento se co rrelacionó con los parámetros espirométricos para obtener una ecuación de ajuste. La FVC se correlacionó en un 70% con los 3 cuartiles de R7, se obtuvieron 3 ecuaciones con un ajuste del 60%. El FEV1 se correlacionó en un 70% con el Q50% de R7, obteniéndose una ecuación con un ajuste del 40%. El FEV1/FVC se correlacionó en un 69% con el Q75% de R2, obteniéndose una ecuación con un ajuste del 60%. Los parámetros espirométricos pueden ser estimados a partir de los componentes de frecuencia portadora implícitos de la señal de impedancia ventilatoria.

Research progress in pulmonary electrical impedance tomography for ventilation functional evaluation following multiple rib fracture / 中华创伤杂志

Multiple rib fracture is a common chest injury that can cause severe pain and seriously affect life quality of the patients. The traditional pulmonary function test can only assess changes in total lung volume and ventilation of the multiple rib fracture, but fails to reveal regional ventilation status in rib fracture area and ventilation differences within the whole lung. Instead, pulmonary electrical impedance tomography (EIT), as a novel bedside technique for ventilation monitoring, has advantages of non-invasiveness, non-use of radiative rays and dynamic visualization of regional ventilation, enabling to quantify ventilation defects and heterogeneity in space and time. Starting with the assessment of ventilation changes and research status of ventilation function in multiple rib fracture and the characteristics of EIT, the authors review the research progress in the evaluation of ventilation function following multiple rib fracture based on EIT, with the aim to provide new insight into the research on ventilation changes after multiple rib fracture.

Ângulo de fase como potencial marcador do estado nutricional de pacientes em terapia intensiva / Phase angle as a potential marker of nutritional status of intensive care patients / El ángulo de fase como posible marcador del estado nutricional de los pacientes de cuidados intensivos

RESUMO Objetivo: verificar associação do ângulo de fase com estado nutricional, tempo de internação e óbito de pacientes críticos. Métodos: estudo longitudinal com 57 pacientes críticos avaliados na admissão em unidade de terapia intensiva durante o ano de 2019, no interior de São Paulo - BR. O ângulo de fase foi obtido por bioimpedância elétrica, e a avaliação nutricional, pelo instrumento de avaliação subjetiva global e antropometria. Os dados foram associados ao tempo de internação e óbito. Para a análise, utilizaram-se testes de Mann-Whitney e Qui-quadrado de Pearson. Resultados: na avaliação subjetiva global, 59,6% dos pacientes apresentavam risco nutricional, e em 91,2% o ângulo de fase estava baixo. A desnutrição foi associada ao maior tempo de internação hospitalar (p=0,001) em unidade de terapia intensiva (p =0,023). Verificou-se tendência ao óbito no grupo com risco nutricional (p=0,054). Conclusão: o ângulo de fase pode contribuir para melhor acurácia da avaliação nutricional, principalmente, quando combinado com outros métodos de avaliação.

ABSTRACT Objective: to verify the association of phase angle with nutritional status, length of hospitalization and death in critically ill patients. Methods: longitudinal study with 57 critically ill patients evaluated upon admission to an intensive care unit during the year 2019, in the countryside of São Paulo - BR. The phase angle was obtained by electrical bioimpedance, and nutritional assessment, by the global subjective assessment instrument and anthropometry. The data were associated with the time of hospitalization and death. For the analysis, Mann-Whitney and Pearson's chi-square tests were used. Results: in the global subjective evaluation, 59.6% of the patients presented nutritional risk, and in 91.2% the phase angle was low. Malnutrition was associated with longer hospital stay (p=0.001) in intensive care unit (p=0.023). There was a tendency to death in the group with nutritional risk (p=0.054). Conclusion: The phase angle can contribute to a better accuracy in nutritional assessment, especially when combined with other assessment methods.

RESUMEN Objetivo: Verificar la asociación del ángulo de fase con el estado nutricional, la duración de la estancia hospitalaria y la muerte en pacientes críticos. Métodos: estudio longitudinal con 57 pacientes críticos evaluados al ingreso en la unidad de cuidados intensivos durante el año 2019, en el interior de São Paulo - BR. El ángulo de fase se obtuvo mediante bioimpedancia eléctrica, y la valoración nutricional, mediante el instrumento de valoración subjetiva global y la antropometría. Los datos se asociaron al momento de la hospitalización y a la muerte. Para el análisis se utilizaron las pruebas de Mann-Whitney y Chi-cuadrado de Pearson. Resultados: en la evaluación subjetiva global, el 59,6% de los pacientes presentó riesgo nutricional, y en el 91,2% el ángulo de fase fue bajo. La desnutrición se asoció a una mayor estancia hospitalaria (p=0,001) en la unidad de cuidados intensivos (p=0,023). Hubo una tendencia a la muerte en el grupo con riesgo nutricional (p=0,054). Conclusión: el ángulo de fase puede contribuir a una mayor precisión en la evaluación nutricional, especialmente cuando se combina con otros métodos de evaluación.

Espectroscopia de impedancia eléctrica, una herramienta para aplicaciones biotecnológicas con Lactobacillus casei ATCC 393 / Electrical impedance spectroscopy, a tool for biotechnological applications with Lactobacillus casei ATCC 393

RESUMEN La aplicación de espectroscopia de impedancia eléctrica (EIE), es una técnica que se utiliza para monitorear, detectar y cuantificar microorganismos de interés biotecnológico, con la medición de parámetros eléctricos de respuesta rápida de un medio inoculado a temperatura y agitación constante mediante electrodos sumergidos. Realizando una comparación del modelo de crecimiento y el recuento en placa con los parámetros eléctricos de respuesta, se puede dar una correlación para romper la barrera tecnológica entre la microbiología clásica y los métodos rápidos de detección. La comparación de ambas técnicas fue realizada para determinar el máximo crecimiento de Lactobacillus casei (L. casei) ATCC 393. Se encontró que tras la inoculación, después de 24 h en condiciones microaerofílicas (37 °C), el máximo crecimiento microbiano fue registrado por medio de la EIE, mediante los parámetros -Z- (29,1057) y Deg-Deg0 (24,555°). En contraste con la técnica de conteo en placa, el crecimiento máximo se estimó a las 9 h. Los datos experimentales obtenidos mediante la EIE fueron ajustados por un circuito RC en serie, posteriormente, las curvas generadas fueron ajustadas a los modelos de crecimiento de Gompertz y Boltzman. Usando la técnica de EIE, la impedancia del medio resultó el parámetro más eficiente para la estimación del pico máximo exponencial de crecimiento de L. casei. Se demostró que la EIE constituye una alternativa para la detección rápida de la concentración microbiana en procesos de producción de biomasa para la elaboración de productos alimenticios probióticos.

ABSTRACT The application of electrical impedance spectroscopy (EIS) is a technique used to monitor, detect and quantify microorganisms of biotechnological interest, with the measurement of electrical parameters of rapid response of a medium inoculated at temperature and constant agitation by submerged electrodes. By making a comparison of the growth model and the plate count with the electrical response parameters, a correlation can be made to break the technological barrier between classical microbiology and rapid detection methods. The comparison of both techniques was performed to determine the maximum growth of Lactobacillus casei (L. casei) ATCC 393. It was found that after inoculation, after 24 h under microaerophilic conditions (37 °C), the maximum microbial growth was recorded by medium of the EIE, using the parameters -Z- (29,1057) and Deg-Deg0 (24,555°). In contrast to the plate count technique, maximum growth was estimated at 9 h. The experimental data obtained through the EIE were adjusted by a series RC circuit; later, the generated curves were adjusted to the growth models of Gompertz and Boltzman. Using the EIE technique, the impedance of the medium was the most efficient parameter for the estimation of the maximum exponential growth peak of L. casei. It was demonstrated that the EIE constitutes an alternative for the rapid detection of the microbial concentration in biomass production processes for the elaboration of probiotic food products.

Ângulo de fase para avaliar risco ou cicatrização de lesões: revisão sistemática / Phase angle for assessing lesion risk or healing: a systematic review / Ángulo de fase para evaluar el riesgo o la cicatrización de lesiones: revisión sistemática

OBJETIVO: Avaliar a efetividade do ângulo de fase medido por bioimpedância elétrica como preditor para avaliação de cicatrização em pacientes com lesões cutâneas ou risco de desenvolvê-las. MÉTODO: Revisão sistemática operacionalizada segundo metodologia Joanna Briggs Institute, recomendações checklist PRISMA. A amostra contemplou pacientes acima de 18 anos com lesões cutâneas variadas. RESULTADOS: Quatro estudos demonstraram o uso do ângulo de fase para o desfecho cicatrização e um estudo apontou uma possível relação do ângulo de fase com previsão de surgimento e risco de lesão por pressão. Foram obtidos pontos de cortes para determinadas lesões. Por não ter sido possível metanálise, se propõe a realização de estudos primários sobre o tema deste estudo. CONCLUSÃO: Apesar de serem poucos os trabalhos científicos com o tema proposto, foi possível demonstrar evidência moderada para o desfecho "cicatrização" e baixa para o desfecho "risco de lesão". Registro no PROSPERO com número CRD420201549.

OBJECTIVE: To assess the effectiveness of the phase angle measured by electrical bioimpedance as a predictor for healing evaluation in patients with skin lesions or risk of developing them. METHOD: A systematic review operationalized according to Joanna Briggs Institute methodology, PRISMA checklist recommendations. The sample included patients over 18 years old with varied skin lesions. RESULTS: Four studies demonstrated the use of phase angle for the healing outcome and one study indicated a possible relationship between phase angle and the prediction of the onset and risk of pressure ulcer. Cut-off points were obtained for certain lesions. As it was not possible to perform a meta-analysis, it is proposed to conduct primary studies on the theme of this study. CONCLUSION: Although there are few scientific papers with the theme proposed, it was possible to demonstrate moderate evidence for the "healing" outcome and low evidence for the "risk of lesion" outcome. Registration in PROSPERO with number CRD420201549.

OBJETIVO: Evaluar la efectividad del ángulo de fase medido por bioimpedancia eléctrica como predictor para la evaluación de la cicatrización en pacientes con lesiones cutáneas o riesgo de desarrollarlas. MÉTODO: Revisión sistemática realizada según la metodología del Joanna Briggs Institute, recomendaciones checklist PRISMA. La muestra incluyó a pacientes mayores de 18 años con diferentes lesiones cutáneas. RESULTADOS: Cuatro estudios demostraron el uso del ángulo de fase para el resultado cicatrización y un estudio señaló una posible relación entre el ángulo de fase y la previsión de la aparición y el riesgo de lesión por presión. Se obtuvieron puntos de corte para ciertas lesiones. Como no fue posible realizar un metaanálisis, se propone realizar estudios primarios sobre el tema de este estudio. CONCLUSIÓN: Aunque hay pocos estudios científicos sobre el tema propuesto, fue posible demostrar evidencia moderada para el resultado "cicatrización" y baja para el resultado "riesgo de lesión". Inscripción en PROSPERO con número CRD420201549.

Pendelluft volume during double-triggered asynchronous breaths under pressure support ventilation: a prospective physiological study / 中华危重病急救医学

Objective:To investigate the relationship between double-triggering and abnormal movement of air in the lungs (pendelluft phenomenon) under pressure support ventilation (PSV).Methods:A prospective observational study was conducted, postoperative patients admitted to department of critical care medicine of Beijing Tiantan Hospital, Capital Medical University from April 1, 2019 to August 31, 2020 and received invasive mechanical ventilation with PSV mode were enrolled. Electrical impedance tomography (EIT) monitoring was performed. Airway pressure-time, flow-time, global and regional impedance-time curves were synchronously collected and analyzed offline. The volume of abnormal movement of air in the lungs at the beginning of inspiration was measured and defined as pendelluft volume. Double-triggered breaths were identified by trained researchers. Pendelluft volume during double-triggering was measured including the first triggered breath, the double-triggered breath, and the breath immediately following the double-triggered breath. Pendelluft volume was also measured for normal breath during the study. According to the frequency of double-triggering, patients were divided into severe (≥1 time/min) and non-severe double-triggering group. Pendelluft volume, parameters of respiratory mechanics, and clinical outcomes between the two groups were compared.Results:In 40 enrolled patients, a total of 9 711 breaths [(243±63) breaths/patient] were collected and analyzed, among which 222 breaths (2.3%) were identified as double-triggering. The Kappa of interobserver reliability to detect double-triggering was 0.964 [95% confidence interval (95% CI) was 0.946-0.982]. In 222 double-triggered breaths, pendelluft volume could not be measured in 7 breaths (3.2%), but the pendelluft phenomenon did exist as shown by opposite regional impedance change at the beginning of double-triggered inspiration. Finally, pendelluft volume was measured in 215 double-triggered breaths. Meanwhile, 400 normal breaths (10 normal breaths randomly selected for each patient) were identified as control. Compared with normal breath, pendelluft volume significantly increased in the first breath, the double-triggered breath, and the following normal breath [mL: 3.0 (1.4, 6.4), 8.3 (3.6, 13.2), 4.3 (1.9, 9.1) vs. 1.4 (0.7, 2.8), all P < 0.05]. Patients in severe double-triggering, pendelluft volume of normal breath and double-triggered breath were significantly higher than those in non-severe double-triggering group [mL: 1.8 (0.9, 3.2) vs. 1.1 (0.5, 2.1), P < 0.001; 8.5 (3.9, 13.4) vs. 2.0 (0.6, 9.1), P = 0.008]. Patients in severe double-triggering group had significantly higher respiratory rate than that in the non-severe double-triggering group (breaths/min: 20.9±3.5 vs. 15.2±3.7, P < 0.001). There were no significant differences in other respiratory mechanics parameters and main clinical outcomes between the two groups. Conclusions:During PSV, the abnormal movement of air in the lungs (pendelluft phenomenon) was more likely to occur in double-triggering especially in double-triggered breath. The more frequent the double-triggering occurred, the more serious the pendelluft phenomenon was. A higher pendelluft volume of normal breath and a higher respiratory rate were related to severity of double-triggering.

Uso da CPAP como alternativa para realização do teste de apneia durante determinação da morte encefálica em pacientes hipoxêmicos. Relato de dois casos / Use of CPAP as an alternative to the apnea test during the determination of brain death in hypoxemic patients. Report of two cases

RESUMO O teste de apneia com desconexão do ventilador mecânico representa riscos durante a determinação da morte encefálica, especialmente em pacientes hipoxêmicos. Descrevemos a realização do teste de apneia sem desconexão do ventilador mecânico em dois pacientes. O primeiro caso é o de um menino de 8 anos, admitido com hipoxemia grave por pneumonia. Apresentou parada cardiorrespiratória, seguida de coma não responsivo por encefalopatia hipóxico-isquêmica. Dois exames clínicos constataram ausência de reflexos de tronco, e o Doppler transcraniano revelou parada circulatória encefálica. Realizaram-se três tentativas de teste de apneia, que foram interrompidas por hipoxemia, sendo então realizado teste de apneia sem desconexão do ventilador mecânico, ajustando a pressão contínua nas vias aéreas em 10cmH2O e fração inspirada de oxigênio em 100%. A saturação de oxigênio manteve-se em 100% por 10 minutos. A gasometria pós-teste foi a seguinte: pH de 6,90, pressão parcial de oxigênio em 284,0mmHg, pressão parcial de dióxido de carbono em 94,0mmHg e saturação de oxigênio em 100%. O segundo caso é de uma mulher de 43 anos, admitida com hemorragia subaracnóidea (Hunt-Hess V e Fisher IV). Dois exames clínicos constataram coma não responsivo e ausência de todos os reflexos de tronco. A cintilografia cerebral evidenciou ausência de captação de radioisótopos no parênquima cerebral. A primeira tentativa do teste de apneia foi interrompida após 5 minutos por hipotermia (34,9oC). Após reaquecimento, o teste de apneia foi repetido sem desconexão do ventilador mecânico, evidenciando-se manutenção do volume residual funcional com tomografia de bioimpedância elétrica. Gasometria pós-teste de apneia apresentava pH em 7,01, pressão parcial de oxigênio em 232,0mmHg, pressão parcial de dióxido de carbono 66,9mmHg e saturação de oxigênio em 99,0%. O teste de apneia sem desconexão do ventilador mecânico permitiu a preservação da oxigenação em ambos os casos. O uso de pressão contínua nas vias aéreas durante o teste de apneia parece ser uma alternativa segura para manter o recrutamento alveolar e a oxigenação durante determinação da morte encefálica.

ABSTRACT The apnea test, which involves disconnection from the mechanical ventilator, presents risks during the determination of brain death, especially in hypoxemic patients. We describe the performance of the apnea test without disconnection from the mechanical ventilator in two patients. The first case involved an 8-year-old boy admitted with severe hypoxemia due to pneumonia. He presented with cardiorespiratory arrest, followed by unresponsive coma due to hypoxic-ischemic encephalopathy. Two clinical exams revealed the absence of brainstem reflexes, and transcranial Doppler ultrasound revealed brain circulatory arrest. Three attempts were made to perform the apnea test, which were interrupted by hypoxemia; therefore, the apnea test was performed without disconnection from the mechanical ventilator, adjusting the continuous airway pressure to 10cmH2O and the inspired fraction of oxygen to 100%. The oxygen saturation was maintained at 100% for 10 minutes. Posttest blood gas analysis results were as follows: pH, 6.90; partial pressure of oxygen, 284.0mmHg; partial pressure of carbon dioxide, 94.0mmHg; and oxygen saturation, 100%. The second case involved a 43-year-old woman admitted with subarachnoid hemorrhage (Hunt-Hess V and Fisher IV). Two clinical exams revealed unresponsive coma and absence of all brainstem reflexes. Brain scintigraphy showed no radioisotope uptake into the brain parenchyma. The first attempt at the apnea test was stopped after 5 minutes due to hypothermia (34.9°C). After rewarming, the apnea test was repeated without disconnection from the mechanical ventilator, showing maintenance of the functional residual volume with electrical bioimpedance. Posttest blood gas analysis results were as follows: pH, 7.01; partial pressure of oxygen, 232.0mmHg; partial pressure of carbon dioxide, 66.9mmHg; and oxygen saturation, 99.0%. The apnea test without disconnection from the mechanical ventilator allowed the preservation of oxygenation in both cases. The use of continuous airway pressure during the apnea test seems to be a safe alternative in order to maintain alveolar recruitment and oxygenation during brain death determination.