Assessment of Postnatal Pulmonary Adaption in Bovine Neonates Using Electric Impedance Tomography (EIT)

Several aspects of postnatal pulmonary adaption in the bovine neonate remain unclear, particularly the dynamics and regional ventilation of the lungs. We used electric impedance tomography (EIT) to measure changes in ventilation in the first 3 weeks of life in 20 non-sedated neonatal calves born without difficulty in sternal recumbency. Arterial blood gas variables were determined in the first 24 h after birth. Immediately after birth, dorsal parts of the lungs had 4.53% ± 2.82% nondependent silent spaces (NSS), and ventral parts had 5.23% ± 2.66% dependent silent spaces (DSS). The latter increased in the first hour, presumably because of gravity-driven ventral movement of residual amniotic fluid. The remaining lung regions had good ventilation immediately after birth, and the percentage of lung regions with high ventilation increased significantly during the study period. The centre of ventilation was always dorsal to and on the right of the theoretical centre of ventilation. The right lung was responsible for a significantly larger proportion of ventilation (63.84% ± 12.74%, p < 0.00001) compared with the left lung. In the right lung, the centrodorsal lung area was the most ventilated, whereas, in the left lung, it was the centroventral area. Tidal impedance changes, serving as a surrogate for tidal volume, increased in the first 3 weeks of life (p < 0.00001). This study shows the dynamic changes in lung ventilation in the bovine neonate according to EIT measurements. The findings form a basis for the recognition of structural and functional lung disorders in neonatal calves.

Feasibility of Using Electrical Impedance Spectroscopy for Assessing Biological Cell Damage during Freezing and Thawing

This study was performed to test bioimpedance as a tool to detect the effect of different thawing methods on meat quality to aid in the eventual creation of an electric impedance-based food quality monitoring system. The electric impedance was measured for fresh pork, thawed pork, and during quick and slow thawing. A clear difference was observed between fresh and thawed samples for both impedance parameters. Impedance was different between the fresh and the frozen-thawed samples, but there were no impedance differences between frozen-thawed samples and the ones that were frozen-thawed and then stored at +3 °C for an additional 16 h after thawing. The phase angle was also different between fresh and the frozen-thawed samples. At high frequency, there were small, but clear phase angle differences between frozen-thawed samples and the samples that were frozen-thawed and subsequently stored for more than 16 h at +3 °C. Furthermore, the deep learning model LSTM-RNN (long short-term memory recurrent neural network) was found to be a promising way to classify the different methods of thawing.

Neurally Adjusted Ventilatory Assistance and Synchronized Intermittend Mandatory Ventilation in Children Assessed by Electrical Impedance Segmentography: A Prospective Randomized Case-Control Crossover Trial

Background: Assessing relative differences of integrated impedance as a surrogate of volume changes between neurally adjusted ventilatory assist (NAVA) and synchronized intermittent mandatory ventilation (SIMV) by using electric impedance segmentography in children.Methods: Performed as a prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. The children were randomized in two groups; one that was started on neurally adjusted ventilatory assist and the other on synchronized intermittent mandatory ventilation. During ventilation, electric impedance segmentography measurements were recorded.Results: The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p=0.04) and second crossover (median 0.50, IQR 0-0.88, p=0.05) as well as across total impedance (0.52 IQR 0-0.87; p=0.002). During neurally adjusted ventilatory assist children showed a shift of impedance towards caudal lung segments, compared to synchronized intermittent mandatory ventilation.Conclusion: Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. Segmental measurements, however, were of low reproducibility due to various limiting factors in its application. For further evaluation, larger prospective clinical trials are necessary.