RESUMEN
PURPOSE: To determine normative data for the inferior vena cava (VCI) diameter in euvolemic children and its correlation with different somatic parameters in a pediatric population at one center in Europe. MATERIALS AND METHODS: This prospective observational study enrolled healthy children aged 4 weeks to 18y that visited our outpatient clinic. Weight, height, body surface area, and age were recorded. The children were grouped according to weight, as follows (80 children/group): <â10âkg, 10-19.9âkg, 20-29.9âkg, 30-59.9âkg, and 60-90âkg. Children were placed in a supine position and, during quiet respiration, the maximum and minimum VCI diameters were measured with M-mode ultrasonography. The collapsibility index (CI) was also automatically calculated for each subject: CIâ=â[VCI maximum (expiratory) diameter - VCI minimum (inspiratory) diameter]/VCI maximum (expiratory) diameter. RESULTS: From May 2016 through November 2018 we retrieved data for 415 children that underwent VCI diameter evaluations. 400 children were included (mean age: 7.8yâ± 5.8, mean weight: 32âkg ±â24.4, 46â% girls). The VCImax and the VCImin were significantly correlated with age (râ=â0.867, pâ<â0.001, râ=â0.797, pâ<â0.001), height (râ=â0.840, pâ<â0.001, râ=â0.772, pâ<â0.001), weight (râ=â0.858, pâ<â0.001, râ=â0.809, pâ<â0.001), and BSA (râ=â0.878, pâ<â0.001, râ=â0.817, pâ<â0.001). Correlations between the CI and age, weight, height, and BSA were not statistically significant. CONCLUSION: This prospective study provided reference values for sonographic measurements of VCI diameters in euvolemic children and might greatly assist in assessing fluid status in sick children.
Asunto(s)
Vena Cava Inferior , Niño , Europa (Continente) , Femenino , Humanos , Masculino , Estudios Prospectivos , Valores de Referencia , Ultrasonografía , Vena Cava Inferior/diagnóstico por imagenRESUMEN
We present a novel, free-standing low-temperature GaAs (LT-GaAs) photoconductive switch and demonstrate its femtosecond performance. A 1-microm-thick layer of a single-crystal LT-GaAs was patterned into 5-10-microm-wide and 15-30-microm-long bars, separated from their GaAs substrate and, subsequently, placed across gold coplanar transmission lines deposited on a Si substrate, forming a photoconductive switch. The switch was excited with 110-fs-wide optical pulses, and its photoresponse was measured with an electro-optic sampling system. Using 810-nm optical radiation, we recorded an electrical transient as short as 360 fs (1.25 THz, 3-dB bandwidth) and established that the photo-carrier lifetime in our LT-GaAs was 150 fs. Our free-standing devices exhibited quantum efficiency of the order of approximately 7%, and their photoresponse amplitude was a linear function of the applied voltage bias, as well as a linear function of the excitation power, below a well-defined saturation threshold.