Modular and Portable System Design for 3D Imaging of Breast Tumors Using Electrical Impedance Tomography.

This paper presents a prototype of a portable and modular electrical impedance tomography (EIT) system for breast tumor detection. The proposed system uses MATLAB to generate three-dimensional representations of breast tissue. The modular architecture of the system allows for flexible customization and scalability. It consists of several interconnected modules. Each module can be easily replaced or upgraded, facilitating system maintenance and future enhancements. Testing of the prototype has shown promising results in preliminary screening based on experimental studies. Agar models were used for the experimental stage of this project. The 3D representations provide clinicians with valuable information for accurate diagnosis and treatment planning. Further research and refinement of the system is warranted to validate its performance in future clinical trials.

Effect of Oral Zinc Supplementation on Phase Angle and Bioelectrical Impedance Vector Analysis in Duchenne Muscular Dystrophy: A Non-Randomized Clinical Trial.

Zinc plays a crucial role in cell structure and functionality. Neurodegenerative Duchenne muscular dystrophy (DMD) alters muscle membrane structure, leading to a loss of muscle mass and strength. The objective of this study was to evaluate the changes in phase angle (PA) and bioelectrical impedance vector analysis (BIVA) results in patients with DMD after oral zinc supplementation. This clinical trial included 33 boys aged 5.6 to 24.5 years diagnosed with DMD. They were divided into three groups according to age (G1, G2, and G3) and supplemented with oral zinc. The mean serum zinc concentration was 74 µg/dL, and 29% of patients had concentrations below the reference value. The baseline values (mean (standard deviation)) of the bioelectrical impedance parameters PA, resistance (R), and reactance (Xc) were 2.59° (0.84°), 924.36 (212.31) Ω, and 39.64 (8.41) Ω, respectively. An increase in R and a decrease in PA and lean mass proportional to age were observed, along with a negative correlation (r = -0.614; p < 0.001) between age and PA. The average cell mass in G1 was greater than that in G3 (p = 0.012). There were no significant differences in serum zinc levels or bioelectrical impedance parameters before and after zinc supplementation. We conclude that this population is at risk of zinc deficiency and the proposed dosage of zinc supplementation was not sufficient to alter serum zinc levels, PA and BIVA results.

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.

Exploring the Relationship between Mechanical Properties and Electrical Impedance in Cement-Based Composites Incorporating Gold Nanoparticles.

Structural health monitoring applications have gained significant attention in recent research, particularly in the study of the mechanical-electrical properties of materials such as cement-based composites. While most researchers have focused on the piezoresistive properties of cement-based composites under compressive stress, exploring the electrical impedance of such materials can provide valuable insights into the relationship between their mechanical and electrical characteristics. In this study, we investigated the connection between the mechanical properties and electrical impedance of cement-based composites modified with Au nanoparticles. Cylindrical samples with dimensions of 3 cm in diameter and 6 cm in length were prepared with a ratio of w/c = 0.47. The Au nanoparticles (Au NPs) were synthesized using pulsed laser ablation in liquids, and their size distribution was analyzed through dynamical light scattering. Mechanical properties were evaluated by analyzing the Young modulus derived from strain-stress curves obtained at various force rates. Electrical properties were measured by means of electrical impedance spectroscopy. The experimental results revealed a notable reduction of 91% in the mechanical properties of Au NPs-cement compounds, while their electrical properties demonstrated a significant improvement of 65%. Interestingly, the decrease in mechanical properties resulting from the inclusion of gold nanoparticles in cementitious materials was found to be comparable to that resulting from variations in the water/cement ratios or the hydration reaction.

First real-time imaging of bronchoscopic lung volume reduction by electrical impedance tomography.

BACKGROUND: Bronchoscopic lung volume reduction (BLVR) with one-way endobronchial valves (EBV) has better outcomes when the target lobe has poor collateral ventilation, resulting in complete lobe atelectasis. High-inspired oxygen fraction (FIO2) promotes atelectasis through faster gas absorption after airway occlusion, but its application during BLVR with EBV has been poorly understood. We aimed to investigate the real-time effects of FIO2 on regional lung volumes and regional ventilation/perfusion by electrical impedance tomography (EIT) during BLVR with EBV. METHODS: Six piglets were submitted to left lower lobe occlusion by a balloon-catheter and EBV valves with FIO2 0.5 and 1.0. Regional end-expiratory lung impedances (EELI) and regional ventilation/perfusion were monitored. Local pocket pressure measurements were obtained (balloon occlusion method). One animal underwent simultaneous acquisitions of computed tomography (CT) and EIT. Regions-of-interest (ROIs) were right and left hemithoraces. RESULTS: Following balloon occlusion, a steep decrease in left ROI-EELI with FIO2 1.0 occurred, 3-fold greater than with 0.5 (p < 0.001). Higher FIO2 also enhanced the final volume reduction (ROI-EELI) achieved by each valve (p < 0.01). CT analysis confirmed the denser atelectasis and greater volume reduction achieved by higher FIO2 (1.0) during balloon occlusion or during valve placement. CT and pocket pressure data agreed well with EIT findings, indicating greater strain redistribution with higher FIO2. CONCLUSIONS: EIT demonstrated in real-time a faster and more complete volume reduction in the occluded lung regions under high FIO2 (1.0), as compared to 0.5. Immediate changes in the ventilation and perfusion of ipsilateral non-target lung regions were also detected, providing better estimates of the full impact of each valve in place. TRIAL REGISTRATION: Not applicable.

Impact of extended lung protection during mechanical ventilation on lung recovery in patients with COVID-19 ARDS: a phase II randomized controlled trial.

BACKGROUND: Protective ventilation seems crucial during early Acute Respiratory Distress Syndrome (ARDS), but the optimal duration of lung protection remains undefined. High driving pressures (ΔP) and excessive patient ventilatory drive may hinder lung recovery, resulting in self-inflicted lung injury. The hidden nature of the ΔP generated by patient effort complicates the situation further. Our study aimed to assess the feasibility of an extended lung protection strategy that includes a stepwise protocol to control the patient ventilatory drive, assessing its impact on lung recovery. METHODS: We conducted a single-center randomized study on patients with moderate/severe COVID-19-ARDS with low respiratory system compliance (CRS < 0.6 (mL/Kg)/cmH2O). The intervention group received a ventilation strategy guided by Electrical Impedance Tomography aimed at minimizing ΔP and patient ventilatory drive. The control group received the ARDSNet low-PEEP strategy. The primary outcome was the modified lung injury score (mLIS), a composite measure that integrated daily measurements of CRS, along with oxygen requirements, oxygenation, and X-rays up to day 28. The mLIS score was also hierarchically adjusted for survival and extubation rates. RESULTS: The study ended prematurely after three consecutive months without patient enrollment, attributed to the pandemic subsiding. The intention-to-treat analysis included 76 patients, with 37 randomized to the intervention group. The average mLIS score up to 28 days was not different between groups (P = 0.95, primary outcome). However, the intervention group showed a faster improvement in the mLIS (1.4 vs. 7.2 days to reach 63% of maximum improvement; P < 0.001), driven by oxygenation and sustained improvement of X-ray (P = 0.001). The intervention group demonstrated a sustained increase in CRS up to day 28 (P = 0.009) and also experienced a shorter time from randomization to room-air breathing (P = 0.02). Survival at 28 days and time until liberation from the ventilator were not different between groups. CONCLUSIONS: The implementation of an individualized PEEP strategy alongside extended lung protection appears viable. Promising secondary outcomes suggested a faster lung recovery, endorsing further examination of this strategy in a larger trial. Clinical trial registration This trial was registered with ClinicalTrials.gov (number NCT04497454) on August 04, 2020.

Evaluating Dielectric Properties for Assessing Water Content at Acupuncture Points: New Methodology.

Importance: Understanding acupuncture point microenvironments is vital for optimizing treatment efficacy. Evaluating changes in water content at these points can provide further insights into the effects of acupuncture on tissues. Objective: This study aimed to measure tissue dielectric constant (TDC) and assess changes in water content, specifically at stomach 36 (ST36, Zusanli) and spleen 6 (SP6, Sanyinjiao) acupuncture points. Methods: In a controlled, blinded, randomized trial, 113 healthy volunteers were divided into six groups based on TDC sensor diameters (XS, M, and L): three control groups and three acupuncture groups. They were assessed at three time points: T1, baseline; T2, 20 min post-needle withdrawal; and T3, 40 min post-needle withdrawal. Electrical impedance (EI) was also analyzed. Significance level was set at p < 0.001. Results: TDC at ST36 and SP6 significantly decreased with the XS probe at T2 and T3 compared with that at T1 (F8, 452: 54.61). TDC did not significantly vary between T2 and T3 with M and L probes. EI data indicated that the current passage increased in the SP (F2, 226: 39.32) and ST (F2, 226: 37.32) groups during T2 and T3 compared with that during T1 within their respective groups and controls. Conclusions: and Relevance: This study demonstrated the efficacy of TDC measurements in detecting water content fluctuations at acupuncture points and their responses to needles. TDC measurements, which were validated against EI, provide valuable insights into acupuncture point microenvironments and thus help optimize treatments.

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.

Concordance between dual indirect methods for assessing fat percentage.

In the last decades there is a growing interest in the evaluation of human body composition for being an important part of the integral assessment of individuals. Its use has been extended to different disciplines associated with health care (medicine, nutrition, physiotherapy), and to sports and population fields. Specifically, fat percentage can be related to innumerable diseases. However, there are discrepancies in the results of fat percentage measurement measured by different methods. Objective: To evaluate the concordance between two low-cost and easily accessible double indirect methods, which have been used indistinctly in different studies where access to more accurate methods is not available, and to determine fat percentage and its relationship with age, sex, body mass index (BMI), waist circumference, level of physical activity and sedentary hours. Materials and Method: Twenty-four persons between 18 and 38 years and 28 between 39 and 59 years from a university community were evaluated. Calculations were made: BMI, fat % was estimated by anthropometry with a digital adipometer (Skyndex System I USA) and by Electrical Bioimpedance Analysis - BIA (Biody Expert ZM II FRA), physical activity level and sedentary hours were determined with the short IPAQ questionnaire. Pearson's correlation coefficient, Bland & Altman's graphical method and Lin's concordance correlation index were calculated. The significance level p<0.05 was estimated. Results: The fat percentage by anthropometry was: 30.5% ±8.5 (18-38 years) 35.0% ±6.7 (39-59 years); by BIA 27.0% ±7.3 (18-38 years) and 29.2% ±7.0 (39-59 years). Both techniques showed good correlation, but low degree of concordance (Lin index less than 0.9) except for the group of young persons with moderate level of physical activity (0.95). Conclusions: The doubly indirect methods used in the study showed strong correlation, but low concordance, so their use is not recommended indistinctly for the follow-up of a particular case. According to the study data for this specific population in young people with moderate physical activity, follow-up could be performed with either of the two methods.

Pulmonary strain and end-expiratory lung volume during apnea test: a comparative analysis using electrical impedance tomography.

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 patient from invasive mechanical ventilation (iMV) for approximately 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 tomography (EIT), we observed that continuous positive airway pressure during the apnea test (CPAP-AT) effectively 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.

La prueba de apnea es una técnica diagnóstica ampliamente 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 paciente de la ventilación mecánica invasiva (iVM) durante aproximadamente 8 minutos, manteniendo la oxigenación mediante un catéter de insuflación. Esta prueba respalda el diagnóstico de muerte cerebral cuando se determina un aumento de la PaCO 2 superior a 20 mmHg en comparación con el valor inicial o un nivel de PaCO 2 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 (CPAPAT) mitiga eficazmente el colapso pulmonar. Este enfoque 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.

Low Concentrations of Gold Nanoparticles as Electric Charge Carriers in Piezoelectric Cement-Based Materials.

Piezoelectric cement-based composites could serve to monitor the strain state of structural elements or act as self-powered materials in structural health monitoring (SHM) applications. The incorporation of piezoelectric materials as an active phase within cement matrices has presented a highly attractive avenue until today. However, their application is challenged by the low electrical conductivity of the hydrated cement matrix. Gold nanoparticles (Au NPs) possess substantial potential for elevating the free electrical charge within the matrix, increasing its electrical conductivity between the Au NPs and the cement matrix, thereby enhancing the piezoelectric response of the composite. In this sense, the objective of this study is to investigate the effects of incorporating low concentrations of gold nanoparticles (Au NPs) (442 and 658 ppm) on the electrical and piezoelectric properties of cement-based composites. Additionally, this study considers the effects of such properties when the material is cured under a constant electric field. Electrical impedance spectroscopy was used to evaluate the polarization resistance and piezoresistive properties of the material. Additionally, open-circuit potential measurements were taken alongside the application of mechanical loads to assess the piezoelectric activity of the composites. The findings revealed a notable decrease in the composite's total electrical resistance, reaching a value of 1.5 ± 0.2 kΩ, almost four times lower than the reference specimens. In the realm of piezoelectricity, the piezoelectric voltage parameter g33 exhibited a remarkable advancement, improving by a factor of 57 when compared to reference specimens. This significant enhancement can be attributed to both the concentration of Au NPs and the electrical curing process. In summary, the outcomes of this study underscore the feasibility of creating a highly electrically conductive cement-based matrix, using low concentrations of gold nanoparticles as electric charge carries, and indicate the possible piezoelectric behavior of the studied compposite.

Electrical impedance tomography: Usefulness for respiratory physiotherapy in critical illnesses.

Respiratory physiotherapy, including the management of invasive mechanical ventilation (MV) and noninvasive mechanical ventilation (NIV), is a key supportive intervention for critically ill patients. MV has potential for inducing ventilator-induced lung injury (VILI) as well as long-term complications related to prolonged bed rest, such as post-intensive care syndrome and intensive care unit acquired weakness. Physical and respiratory therapy, developed by the critical care team, in a timely manner, has been shown to prevent these complications. In this pathway, real-time bedside monitoring of changes in pulmonary aeration and alveolar gas distribution associated with postural positioning, respiratory physiotherapy techniques and changes in MV strategies can be crucial in guiding these procedures, providing safe therapy and prevention of potential harm to the patient. Along this path, electrical impedance tomography (EIT) has emerged as a new key non-invasive bedside strategy free of radiation, to allow visualization of lung recruitment. This review article presents the main and potential applications of EIT in relation to physiotherapy techniques in the ICU setting.

Bioelectrical Impedance in Premature Newborns and Its Relationship with Diet Therapy in a Neonatal Intensive Care Unit.

(1) Background: To estimate resistance, reactance, and phase angle values among moderate preterm infants and their variation according to neonatal and maternal characteristics and nutritional intake. (2) Methods: This was a cohort that evaluated 43 moderate preterm infants using bioelectrical impedance analysis. The study variables included resistance, reactance, and phase angle measurements, in addition to classification of nutritional intake. (3) Results: Mean resistance was 602.0 ± 118.2 Ω, reactance was 57.2 Ω (IQR = 42.6-65.2), and phase angle was 522° (IQR = 4.1-6.6). Lower resistance values were found in the presence of risky pregnancy (532.2 ± 111.9 Ω vs. 650.9 ± 97.9 Ω, p < 0.001) and lower reactance values, in the presence of harmful maternal lifestyle habits at both the first (p = 0.01) and second assessments (p = 0.01). Eight preterm infants were considered to have insufficient nutritional intake (23.5%); 17, sufficient (50.0%) and 9, partially sufficient (26.5%). There was less reactance among preterm infants with insufficient nutritional intake (p < 0.001). (4) Conclusions: The bioelectrical impedance analysis measurements were within the range of values reported in other studies. There was an association between full diet and adequate nutritional intake with higher resistance values, while a lower reactance value was associated with the presence of risky pregnancy and harmful maternal lifestyle.

Physiological effect of high flow oxygen therapy measured by electrical impedance tomography in single-lung transplantation.

In patients with chronic obstructive pulmonary disease (COPD), single lung transplantation (SLT) is sometimes performed as an alternative to bilateral lung transplantation due to limited organ availability. However, the postoperative management of SLT presents challenges, including complications related to the distinct compliance 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 distribution 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.

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 postoperatorio del SLT presenta desafíos, incluyendo complicaciones relacionadas con la distinta complacencia de cada pulmón. 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.

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.

Dynamic relative regional lung strain estimated by computed tomography and electrical impedance tomography in ARDS patients.

BACKGROUND: In the acute distress respiratory syndrome (ARDS), specific lung regions can be exposed to excessive strain due to heterogeneous disease, gravity-dependent lung collapse and injurious mechanical ventilation. Computed tomography (CT) is the gold standard for regional strain assessment. An alternative tool could be the electrical impedance tomography (EIT). We aimed to determine whether EIT-based methods can predict the dynamic relative regional strain (DRRS) between two levels of end-expiratory pressure (PEEP) in gravity-non-dependent and dependent lung regions. METHODS: Fourteen ARDS patients underwent CT and EIT acquisitions (at end-inspiratory and end-expiratory) at two levels of PEEP: a low-PEEP based on ARDS-net strategy and a high-PEEP titrated according to EIT. Three EIT-based methods for DRRS were compared to relative CT-based strain: (1) the change of the ratio between EIT ventilation and end-expiratory lung impedance in arbitrary units ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]), (2) the change of ΔZ/EELI ratio calibrated to mL ([ΔZml low-PEEP/EELIml low-PEEP]/[ΔZml high-PEEP/EELIml high-PEEP]) using CT data, and (3) the relative change of ∆ZAU (∆ZAU low-PEEP/∆ZAU high-PEEP). We performed linear regressions analysis and calculated bias and limits of agreement to assess the performance of DRRS by EIT in comparison with CT. RESULTS: The DRRS assessed by (ΔZml low-PEEP/EELIml low-PEEP)/(ΔZml high-PEEP/EELIml high-PEEP) and ∆ZAU low-PEEP/∆ZAU high-PEEP showed good relationship and agreement with the CT method (R2 of 0.9050 and 0.8679, respectively, in non-dependent region; R2 of 0.8373 and 0.6588, respectively, in dependent region; biases ranging from - 0.11 to 0.51 and limits of agreement ranging from - 0.73 to 1.16 for both methods and lung regions). Conversely, DRRS based on EELIAU ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]) exhibited a weak negative relationship and poor agreement with the CT method for both non-dependent and dependent regions (R2 ~ 0.3; bias of 3.11 and 2.08, and limits of agreement of - 2.13 to 8.34 and from - 1.49 to 5.64, respectively). CONCLUSION: Changes in DRRS during a PEEP trial in ARDS patients could be monitored using EIT, based on changes in ΔZmL/EELIml and ∆ZAU. The relative change ∆ZAU offers the advantage of not requiring CT data for calibration.

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

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 hyperinflation 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 process, underwent advanced monitoring in order to find the causes of the failure.

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 resultados negativos. Por lo tanto, las pruebas de respiración espontánea pueden fallar y retrasar el proceso de desvinculación 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.

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.