RESUMEN
OBJECTIVE: To understand practices of umbilical venous catheter (UVC) insertion in tertiary level neonatal intensive care units (NICU) and investigate the outcomes of subsequent attempts following a failed initial attempt. STUDY DESIGN: Prospective, multi-center observational study of UVC insertions at tertiary level NICUs between March 2019 and January 2020. RESULTS: Of the 101 UVCs inserted at 4 centers, seventy-two (71%) were central at the first attempt and 50% were central at subsequent attempts. Patients with at least 1 failed attempt at insertion were less likely to have a centrally placed UVC (p = .009). Manipulations were less likely to be required when UVC was centrally placed during the first attempt. Maneuvers such as posterior liver mobilization used during insertion were likely to be associated with successful central placement of UVC (p = .0243). The time to complete the procedure was significantly less when the UVC was central at the first attempt (34.2 ± 20.2 vs 46.9 ± 33.8) (p = .0292). Gestational age, birth weight, and age of the baby at the insertion of the UVC, experience of the provider, and type of catheter were comparable among groups. The Shukla formula was most commonly used by providers to measure the depth of UVC placement. CONCLUSION: Repetitive attempts and manipulations were less likely to be beneficial in the successful central placement of UVC in neonates. Additionally, repetitive attempts at insertion prolonged the overall duration of the procedure.
Asunto(s)
Cateterismo Venoso Central , Cateterismo Periférico , Recién Nacido , Humanos , Cateterismo Periférico/métodos , Estudios Prospectivos , Venas Umbilicales , Peso al Nacer , CatéteresRESUMEN
Low-permeability (unconventional) hydrocarbon reservoirs exhibit a complex nanopore structure and micro (µm) -scale variability in composition which control fluid distribution, displacement and transport processes. Conventional methods for characterizing fluid-rock interaction are however typically performed at a macro (mm) -scale on rock sample surfaces. In this work, innovative methods for the quantification of micro-scale variations in wettability and fluid distribution in a low-permeability oil reservoir was enabled by using an environmental scanning electron microscope. Live imaging of controlled water condensation/evaporation experiments allowed micro-droplet contact angles to be evaluated, while imaging combined with x-ray mapping of cryogenically frozen samples facilitated the evaluation of oil and water micro-droplet contact angles after successive fluid injection. For the first time, live imaging of fluids injected through a micro-injection system has enabled quantification of sessile and dynamic micro-droplet contact angles. Application of these combined methods has revealed dramatic spatial changes in fluid contact angles at the micro-scale, calling into question the applicability of macro-scale observations of fluid-rock interaction.
RESUMEN
Segmentation of the tumor in neuroblastoma is complicated by the fact that the mass is almost always heterogeneous in nature; furthermore, viable tumor, necrosis, and normal tissue are often intermixed. Tumor definition and diagnosis require the analysis of the spatial distribution and Hounsfield unit (HU) values of voxels in computed tomography (CT) images, coupled with a knowledge of normal anatomy. Segmentation and analysis of the tissue composition of the tumor can assist in quantitative assessment of the response to therapy and in the planning of the delayed surgery for resection of the tumor. We propose methods to achieve 3-dimensional segmentation of the neuroblastic tumor. In our scheme, some of the normal structures expected in abdominal CT images are delineated and removed from further consideration; the remaining parts of the image volume are then examined for tumor mass. Mathematical morphology, fuzzy connectivity, and other image processing tools are deployed for this purpose. Expert knowledge provided by a radiologist in the form of the expected structures and their shapes, HU values, and radiological characteristics are incorporated into the segmentation algorithm. In this preliminary study, the methods were tested with 10 CT exams of four cases from the Alberta Children's Hospital. False-negative error rates of less than 12% were obtained in eight of 10 exams; however, seven of the exams had false-positive error rates of more than 20% with respect to manual segmentation of the tumor by a radiologist.