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.

Using EEG total energy as a noninvasively tracking of intracranial (and cerebral perfussion) pressure in an animal model: A pilot study.

PURPOSE: This study aims to describe the total EEG energy during episodes of intracranial hypertension (IH) and evaluate its potential as a classification feature for IH. NEW METHODS: We computed the sample correlation coefficient between intracranial pressure (ICP) and the total EEG energy. Additionally, a generalized additive model was employed to assess the relationship between arterial blood pressure (ABP), total EEG energy, and the odds of IH. RESULTS: The median sample cross-correlation between total EEG energy and ICP was 0.7, and for cerebral perfusion pressure (CPP) was 0.55. Moreover, the proposed model exhibited an accuracy of 0.70, sensitivity of 0.53, specificity of 0.79, precision of 0.54, F1-score of 0.54, and an AUC of 0.7. COMPARISON WITH EXISTING METHODS: The only existing comparable methods, up to our knowledge, use 13 variables as predictor of IH, our model uses only 3, our model, as it is an extension of the generalized model is interpretable and it achieves the same performance. CONCLUSION: These findings hold promise for the advancement of multimodal monitoring systems in neurocritical care and the development of a non-invasive ICP monitoring tool, particularly in resource-constrained environments.

Severe thrombocytopenia associated to bevacizumab in a patient with scleroderma, gastrointestinal angiodysplasias and refractory gastrointestinal bleeding.

This case report discusses the medical history of a 64-year-old woman diagnosed with scleroderma and diffuse gastrointestinal angiodysplasia. The patient received bevacizumab (BVZ) therapy to address gastrointestinal bleeding that was unresponsive to endoscopic treatment. Subsequently, she developed severe thrombocytopenia. Although there were suspicions of an immune-mediated mechanism resulting from BVZ treatment, the laboratory results did not provide conclusive evidence. The patient underwent transfusions, received gamma globulin, and was treated with Romiplostim. Over time, her platelet levels gradually improved, and the bleeding was successfully controlled. It's worth noting that BVZ-induced thrombocytopenia is a relatively rare yet severe adverse effect. Recognizing and understanding the mechanisms behind thrombocytopenia is essential for developing safer treatment approaches. Further research is required to identify potential risk factors associated with this condition.

Novel EEG Metric Correlates with Intracranial Pressure in an Animal Model.

BACKGROUND: Intracranial pressure (ICP) can be continuously and reliably measured using invasive monitoring through an external ventricular catheter or an intraparenchymal probe. We explore electroencephalography (EEG) to identify a reliable real-time noninvasive ICP correlate. METHODS: Using a previously described porcine model of intracranial hypertension, we examined the cross correlation between ICP time series and the slope of the EEG power spectral density as described by ϕ. We calculated ϕ as tan-1 (slope of power spectral density) and normalized it by π, where slope is that of the power-law fit (log frequency vs. log power) to the power spectral density of the EEG signal. Additionally, we explored the relationship between the ϕ time series and cerebral perfusion pressure. A total of 11 intracranial hypertension episodes across three different animals were studied. RESULTS: The mean correlation between ϕ angle and ICP was - 0.85 (0.15); the mean correlation with cerebral perfusion pressure was 0.92 (0.02). Significant correlation occurred at zero lag. In the absence of intracranial hypertension, the absolute value of the ϕ angle was greater than 0.9 (mean 0.936 radians). However, during extreme intracranial hypertension causing cerebral circulatory arrest, the ϕ angle is on average below 0.9 radians (mean 0.855 radians). CONCLUSIONS: EEG ϕ angle is a promising real-time noninvasive measure of ICP/cerebral perfusion using surface electroencephalography.

Permutation Entropy Analysis to Intracranial Hypertension from a Porcine Model.

Intracranial pressure (ICP) monitoring is commonly used in the follow-up of patients in intensive care units, but only a small part of the information available in the ICP time series is exploited. One of the most important features to guide patient follow-up and treatment is intracranial compliance. We propose using permutation entropy (PE) as a method to extract non-obvious information from the ICP curve. We analyzed the results of a pig experiment with sliding windows of 3600 samples and 1000 displacement samples, and estimated their respective PEs, their associated probability distributions, and the number of missing patterns (NMP). We observed that the behavior of PE is inverse to that of ICP, in addition to the fact that NMP appears as a surrogate for intracranial compliance. In lesion-free periods, PE is usually greater than 0.3, and normalized NMP is less than 90% and p(s1)>p(s720). Any deviation from these values could be a possible warning of altered neurophysiology. In the terminal phases of the lesion, the normalized NMP is higher than 95%, and PE is not sensitive to changes in ICP and p(s720)>p(s1). The results show that it could be used for real-time patient monitoring or as input for a machine learning tool.

Minimally Invasive Drainage of Intracerebral Hemorrhage. A South American Experience with the MISTIE Procedure.

BACKGROUND: Intracerebral hemorrhage (ICH) is the second most common subtype of stroke but is associated with greater rates of disability or mortality. One of the factors of a poor prognosis is large hematoma volume. The MISTIE III trial with the aim of decreasing clot size showed that the greater the ICH reduction, the higher likelihood of lower mortality without a net increase in the proportion of patients with severe disability. Our aim is to describe our experience with treating selective patients with ICH per the MISTIE trial protocol in a university hospital in Argentina during 4 years. METHODS: A retrospective analysis was performed of consecutive patients with ICH treated at a single university tertiary-care center from 2017 to 2021 with the MISTIE protocol. RESULTS: We deployed this procedure in 7 patients with a median age of 61 years, median National Institutes of Health Stroke Scale score of 14, an ICH volume of 35 mL and median ICH score of 2. Five of 7 patients achieved the target goal of hematoma reduction; 4 of the patients had a total independence level and 1 needed minimal help at 12 months after discharge. Five patients had a good functional outcome (modified Rankin Scale score 0-3 and extended Glasgow Outcome Scale score 4-8) and 2 patients had died but neither because of consequences of thrombolysis of the intracerebral hemorrhage. We did not find bleeding complications during catheter placement, alteplase infusion, or after catheter removal. CONCLUSIONS: The procedure can be carried out safely in Latin American centers that have experience in managing neurocritical patients.

[Percutaneous tracheostomy guided by bronchoscopy: experience in 235 procedures]. / Traqueostomía percutánea guiada por broncoscopía: experiencia en 235 procedimientos.

Objetivo: Medición de la eficacia y relevamiento de las complicaciones asociadas a la a realización de traqueostomía percutánea (TP) guiada por videobroncoscopia en un hospital universitario de alta complejidad. Materiales y métodos: Estudio observacional retrospectivo realizado entre mayo de 2017 y agosto de 2019. El criterio para la indicación de TP fue desvinculación prolongada de la ventilación mecánica en todos los casos. Incluyó pacientes mayores de 18 años en que se realizó TP electiva guiada por videobroncoscopia. Se registraron variables demográficas, APACHE II y días de ventilación mecánica previos a la TP. La eficacia del procedimiento fue evaluada en base a la tasa de éxito en la ejecución, la necesidad de conversión a técnica abierta. Asimismo, se registraron las complicaciones observadas. Resultados: Se evaluaron 235 procedimientos (149 hombres y 86 mujeres) en pacientes con edad media de 61 años ± 19, un score APACHE II 18 ± 8. La TP pudo ser ejecutada en forma rápida y satisfactoria en todos los pacientes sin requerimiento de conversión a técnica abierta. Se presentaron complicaciones tempranas en el 3,8% (9) de los casos. El sangrado menor fue la complicación más frecuentemente observada en 5 casos (2,1%), hipotensión en 3 casos (1,3%) e hipoxemia transitoria en un caso (0,4%). Asimismo el 2,1% (5) de los casos registró complicaciones tardías. Conclusión: La realización de TP mediante la técnica de dilatador único guiada por videobroncoscopia se describe como un procedimiento efectivo y seguro, que puede realizarse en unidades de cuidados intensivos con baja tasa de complicaciones. Objective: Measurement of the efficacy and complications associated with performing percutaneous tracheostomy (PT) guided by video bronchoscopy. Materials and methods: Retrospective observational study conducted between May 2017 and August 2019. Adult patients who underwent elective PT guided by video bronchoscopy were included. The criteria for the indication of PT was prolonged weaning from mechanical ventilation in all cases. Demographic variables, APACHE II score and days of mechanical ventilation prior to PT were recorded. The efficacy of the procedure was evaluated based on the success rate in the execution, the need for conversion to open technique. Also complications observed were recorded. Results: 235 procedures (149 men and 86 women) were evaluated in patients with an average age of 61 years ± 19 and APACHE II score 18 ± 8. The PT was performed quickly and satisfactorily in all patients without conversion to open technique in any case. Complications occurred in 3.8% (9) of the cases. Minor bleeding was the most frequently observed complication in 5 cases (2.1%), hypotension in 3 cases (1.3%), and transient hypoxemia in one patient (0.4%). Also, 2,1% (5) of the cases presented late complications. Conclusion: Performing PT guided by video bronchoscopy is described as an effective and safe procedure that can be done in intensive care units with a low rate of complications.

Objetivo: Medición de la eficacia y relevamiento de las complicaciones asociadas a la a realización de traqueostomía percutánea (TP) guiada por videobroncoscopia en un hospital universitario de alta complejidad. Materiales y métodos: Estudio observacional retrospectivo realizado entre mayo de 2017 y agosto de 2019. El criterio para la indicación de TP fue desvinculación prolongada de la ventilación mecánica en todos los casos. Incluyó pacientes mayores de 18 años en que se realizó TP electiva guiada por videobroncoscopia. Se registraron variables demográficas, APACHE II y días de ventilación mecánica previos a la TP. La eficacia del procedimiento fue evaluada en base a la tasa de éxito en la ejecución, la necesidad de conversión a técnica abierta. Asimismo, se registraron las complicaciones observadas. Resultados: Se evaluaron 235 procedimientos (149 hombres y 86 mujeres) en pacientes con edad media de 61 años ± 19, un score APACHE II 18 ± 8. La TP pudo ser ejecutada en forma rápida y satisfactoria en todos los pacientes sin requerimiento de conversión a técnica abierta. Se presentaron complicaciones tempranas en el 3,8% (9) de los casos. El sangrado menor fue la complicación más frecuentemente observada en 5 casos (2,1%), hipotensión en 3 casos (1,3%) e hipoxemia transitoria en un caso (0,4%). Asimismo el 2,1% (5) de los casos registró complicaciones tardías. Conclusión: La realización de TP mediante la técnica de dilatador único guiada por videobroncoscopia se describe como un procedimiento efectivo y seguro, que puede realizarse en unidades de cuidados intensivos con baja tasa de complicaciones.

An iterative approach for the optimization of pavement maintenance management at the network level.

Pavement maintenance is one of the major issues of public agencies. Insufficient investment or inefficient maintenance strategies lead to high economic expenses in the long term. Under budgetary restrictions, the optimal allocation of resources becomes a crucial aspect. Two traditional approaches (sequential and holistic) and four classes of optimization methods (selection based on ranking, mathematical optimization, near optimization, and other methods) have been applied to solve this problem. They vary in the number of alternatives considered and how the selection process is performed. Therefore, a previous understanding of the problem is mandatory to identify the most suitable approach and method for a particular network. This study aims to assist highway agencies, researchers, and practitioners on when and how to apply available methods based on a comparative analysis of the current state of the practice. Holistic approach tackles the problem considering the overall network condition, while the sequential approach is easier to implement and understand, but may lead to solutions far from optimal. Scenarios defining the suitability of these approaches are defined. Finally, an iterative approach gathering the advantages of traditional approaches is proposed and applied in a case study. The proposed approach considers the overall network condition in a simpler and more intuitive manner than the holistic approach.