Accuracy evaluation of mainstream and sidestream end-tidal carbon dioxide monitoring during noninvasive ventilation: a randomized crossover trial (MASCAT-NIV trial).

BACKGROUND: The end-tidal partial pressure of carbon dioxide (PETCO2) can be used to estimate the arterial partial pressure of carbon dioxide (PaCO2) in patients who undergo mechanical ventilation via endotracheal intubation. However, no reliable method for measuring PETCO2 during noninvasive ventilation (NIV) has been established. The purpose of this study was to evaluate the correlation and agreement between PaCO2 and PETCO2 measured by these two methods and to compare them in patients who underwent NIV after extubation. METHODS: This study was a randomized, open-label, crossover trial in a mixed intensive care unit. We included patients who were planned for NIV after extubation and for whom the difference between PETCO2 and PaCO2 was ≤ 5 mmHg. We compared mainstream capnography using an inner cup via face mask (the novel method) with sidestream capnography (the previous method) during NIV. The relationships between PaCO2 and PETCO2 were evaluated by computing the Pearson correlation coefficient, and the agreement between PaCO2 and PETCO2 was estimated using the Bland-Altman method. RESULTS: From April 2020 to October 2021, 60 patients were included to the study. PaCO2 and PETCO2 were well correlated in both methods (the novel methods: r = 0.92, P < 0.001; the previous method: r = 0.79, P < 0.001). Mean bias between PaCO2 and PETCO2 measured using the novel method was 2.70 (95% confidence interval [CI], 2.15-3.26) mmHg with 95% limits of agreement (LoA) ranging from - 1.61 to 7.02 mmHg, similar to the result of measurement during SBT (mean bias, 2.51; 95% CI, 2.00-3.02; 95% LoA, - 1.45 to 6.47 mmHg). In contrast, measurement using the previous method demonstrated a larger difference (mean bias, 6.22; 95% CI, 5.22-7.23; 95% LoA, - 1.54 to 13.99 mmHg). CONCLUSION: The current study demonstrated that the novel PETCO2 measurement was superior to the previous method for PaCO2 prediction. During NIV, the novel method may collect as sufficient exhalation sample as during intubation. Continuous PETCO2 measurement combined with peripheral oxygen saturation monitoring is expected to be useful for early recognition of respiratory failure among high-risk patients after extubation. Trial registration UMIN-CTR UMIN000039459. Registered February 11, 2020.

Changes in Imaging and Cognition in Juvenile Rats After Whole-Brain Irradiation.

PURPOSE: In pediatric cancer survivors treated with whole-brain irradiation (WBI), long-term cognitive deficits and morbidity develop that are poorly understood and for which there is no treatment. We describe similar cognitive defects in juvenile WBI rats and correlate them with alterations in diffusion tensor imaging and magnetic resonance spectroscopy (MRS) during brain development. METHODS AND MATERIALS: Juvenile Fischer rats received clinically relevant fractionated doses of WBI or a high-dose exposure. Diffusion tensor imaging and MRS were performed at the time of WBI and during the subacute (3-month) and late (6-month) phases, before behavioral testing. RESULTS: Fractional anisotropy in the splenium of the corpus callosum increased steadily over the study period, reflecting brain development. WBI did not alter the subacute response, but thereafter there was no further increase in fractional anisotropy, especially in the high-dose group. Similarly, the ratios of various MRS metabolites to creatine increased over the study period, and in general, the most significant changes after WBI were during the late phase and with the higher dose. The most dramatic changes observed were in glutamine-creatine ratios that failed to increase normally between 3 and 6 months after either radiation dose. WBI did not affect the ambulatory response to novel open field testing in the subacute phase, but locomotor habituation was impaired and anxiety-like behaviors increased. As for cognitive measures, the most dramatic impairments were in novel object recognition late after either dose of WBI. CONCLUSIONS: The developing brains of juvenile rats given clinically relevant fractionated doses of WBI show few abnormalities in the subacute phase but marked late cognitive alterations that may be linked with perturbed MRS signals measured in the corpus callosum. This pathomimetic phenotype of clinically relevant cranial irradiation effects may be useful for modeling, mechanistic evaluations, and testing of mitigation approaches.

Proton tunneling in low dimensional cesium silicate LDS-1.

In low dimensional cesium silicate LDS-1 (monoclinic phase of CsHSi2O5), anomalous infrared absorption bands observed at 93, 155, 1210, and 1220 cm(-1) are assigned to the vibrational mode of protons, which contribute to the strong hydrogen bonding between terminal oxygen atoms of silicate chain (O-O distance = 2.45 Å). The integrated absorbance (oscillator strength) for those modes is drastically enhanced at low temperatures. The analysis of integrated absorbance employing two different anharmonic double-minimum potentials makes clear that proton tunneling through the potential barrier yields an energy splitting of the ground state. The absorption bands at 93 and 155 cm(-1), which correspond to the different vibrational modes of protons, are attributed to the optical transition between the splitting levels (excitation from the ground state (n = 0) to the first excited state (n = 1)). Moreover, the absorption bands at 1210 and 1220 cm(-1) are identified as the optical transition from the ground state (n = 0) to the third excited state (n = 3). Weak Coulomb interactions in between the adjacent protons generate two types of vibrational modes: symmetric mode (93 and 1210 cm(-1)) and asymmetric mode (155 and 1220 cm(-1)). The broad absorption at 100-600 cm(-1) reveals an emergence of collective mode due to the vibration of silicate chain coupled not only with the local oscillation of Cs(+) but also with the proton oscillation relevant to the second excited state (n = 2).

Enrichment rescues contextual discrimination deficit associated with immediate shock.

Adult animals continue to modify their behavior throughout life, a process that is highly influenced by past experiences. To shape behavior, specific mechanisms of neural plasticity to learn, remember, and recall information are required. One of the most robust examples of adult plasticity in the brain occurs in the dentate gyrus (DG) of the hippocampus, through the process of adult neurogenesis. Adult neurogenesis is strongly upregulated by external factors such as voluntary wheel running (RUN) and environmental enrichment (EE); however, the functional differences between these two factors remain unclear. Although both manipulations result in increased neurogenesis, RUN dramatically increases the proliferation of newborn cells and EE promotes their survival. We hypothesize that the method by which these newborn neurons are induced influences their functional role. Furthermore, we examine how EE-induced neurons may be primed to encode and recognize features of novel environments due to their previous enrichment experience. Here, we gave mice a challenging contextual fear-conditioning (FC) procedure to tease out the behavioral differences between RUN-induced neurogenesis and EE-induced neurogenesis. Despite the robust increases in neurogenesis seen in the RUN mice, we found that only EE mice were able to discriminate between similar contexts in this task, indicating that EE mice might use a different cognitive strategy when processing contextual information. Furthermore, we showed that this improvement was dependent on EE-induced neurogenesis, suggesting a fundamental functional difference between RUN-induced neurogenesis and EE-induced neurogenesis.