Cave monitoring in Hungary: An overview

In this study, already published and new monitoring data are compiled from the Baradla and Béke caves in the Aggtelek Karst, from the Vacska Cave in the Pilis Mountains as well as from the Szemlőhegy and Pálvölgy caves in the Buda Hills. Recent investigations (2019–2020) include monitoring of climatological parameters (e.g., temperature, CO2) measured inside and outside the caves, and the chemical, trace element and stable isotopic compositions of drip waters. In the Baradla Cave, the main focus of the investigation was on the stable isotope composition and the temperature measurements of drip water. In the Vacska Cave, which belongs to the Ajándék-Ariadne cave system, CO2 measurements and drip water collection were conducted in order to perform chemical and stable isotope measurements. In the Szemlőhegy and Pálvölgy caves, the chemical and stable isotope compositions of drip waters at six sites were determined. These datasets were used to characterize the studied caves and the hydrological processes taking place in the karst, and to trace anthropogenic influences. Climatological investigation revealed seasonality in CO2 concentration related to outside temperature variation, indicating a variable ventilation regime in the caves. In addition, the contributions of the winter and summer precipitation to the drip water were also estimated, in order to evaluate the main infiltration period. The knowledge of these parameters plays a crucial role in constraining the carbonate precipitation within the cave. Thus, the dataset compiled in this study can provide a basis for the interpretation of speleothem-based proxies.

Benefit of Physiologically Variable Over Pressure-Controlled Ventilation in a Model of Chronic Obstructive Pulmonary Disease: A Randomized Study

IntroductionThe advantages of physiologically variable ventilation (PVV) based on a spontaneous breathing pattern have been demonstrated in several respiratory conditions. However, its potential benefits in chronic obstructive pulmonary disease (COPD) have not yet been characterized. We used an experimental model of COPD to compare respiratory function outcomes after 6 h of PVV versus conventional pressure-controlled ventilation (PCV).Materials and MethodsRabbits received nebulized elastase and lipopolysaccharide throughout 4 weeks. After 30 days, animals were anesthetized, tracheotomized, and randomized to receive 6 h of physiologically variable (n = 8) or conventional PCV (n = 7). Blood gases, respiratory mechanics, and chest fluoroscopy were assessed hourly.ResultsAfter 6 h of ventilation, animals receiving variable ventilation demonstrated significantly higher oxygenation index (PaO2/FiO2 441 ± 37 (mean ± standard deviation) versus 354 ± 61 mmHg, p < 0.001) and lower respiratory elastance (359 ± 36 versus 463 ± 81 cmH2O/L, p < 0.01) than animals receiving PCV. Animals ventilated with the variable mode also presented less lung derecruitment (decrease in lung aerated area, –3.4 ± 9.9 versus –17.9 ± 6.7%, p < 0.01) and intrapulmonary shunt fraction (9.6 ± 4.1 versus 17.0 ± 5.8%, p < 0.01).ConclusionPVV applied to a model of COPD improved oxygenation, respiratory mechanics, lung aeration, and intrapulmonary shunt fraction compared to conventional ventilation. A reduction in alveolar derecruitment and lung tissue stress leading to better aeration and gas exchange may explain the benefits of PVV.

Physiologically variable ventilation reduces regional lung inflammation in a pediatric model of acute respiratory distress syndrome

Background Benefits of variable mechanical ventilation based on the physiological breathing pattern have been observed both in healthy and injured lungs. These benefits have not been characterized in pediatric models and the effect of this ventilation mode on regional distribution of lung inflammation also remains controversial. Here, we compare structural, molecular and functional outcomes reflecting regional inflammation between PVV and conventional pressure-controlled ventilation (PCV) in a pediatric model of healthy lungs and acute respiratory distress syndrome (ARDS). Methods New-Zealand White rabbit pups (n = 36, 670 ± 20 g [half-width 95% confidence interval]), with healthy lungs or after induction of ARDS, were randomized to five hours of mechanical ventilation with PCV or PVV. Regional lung aeration, inflammation and perfusion were assessed using x-ray computed tomography, positron-emission tomography and single-photon emission computed tomography, respectively. Ventilation parameters, blood gases and respiratory tissue elastance were recorded hourly. Results Mechanical ventilation worsened respiratory elastance in healthy and ARDS animals ventilated with PCV (11 ± 8%, 6 ± 3%, p < 0.04), however, this trend was improved by PVV (1 ± 4%, − 6 ± 2%). Animals receiving PVV presented reduced inflammation as assessed by lung normalized [18F]fluorodeoxyglucose uptake in healthy (1.49 ± 0.62 standardized uptake value, SUV) and ARDS animals (1.86 ± 0.47 SUV) compared to PCV (2.33 ± 0.775 and 2.28 ± 0.3 SUV, respectively, p < 0.05), particularly in the well and poorly aerated lung zones. No benefit of PVV could be detected on regional blood perfusion or blood gas parameters. Conclusions Variable ventilation based on a physiological respiratory pattern, compared to conventional pressure-controlled ventilation, reduced global and regional inflammation in both healthy and injured lungs of juvenile rabbits.