ABSTRACT
BACKGROUND: Point of care ultrasound (PoCUS) is a useful tool for the early diagnosis of thrombosis related to the central venous catheter for dialysis (TR-CVCd). However, the application of PoCUS is still not common as a bedside imaging examination and TR-CVCd remains often underdiagnosed in the routine practice. The aim of this study was to investigate if a compression technique for the diagnosis of TR-CVCd blindly performed by PoCUS experts and medical students is accurate when compared to a Doppler study. METHODS: Two medical students without prior knowledge in PoCUS received a short theoretical-practical training to evaluate TR-CVCd of the internal jugular vein by means of the ultrasound compression technique. After the training phase, patients with central venous catheter for dialysis (CVCd) were evaluated by the students in a private hemodialysis clinic. The results were compared to those obtained on the same population by doctors with solid experience in PoCUS, using both the compression technique and the color Doppler. RESULTS: Eighty-one patients were eligible for the study and the prevalence of TR-CVCd diagnosed by Doppler was 28.4%. The compression technique performed by the students and by experts presented, respectively, a sensitivity of 59.2% (CI 51.6-66.8) vs 100% and a specificity of 89.6% (CI 84.9-94.3) vs 94.8% (CI 91.4-98.2). CONCLUSION: The compression technique in the hands of PoCUS experts demonstrated high accuracy in the diagnosis of TR-CVCd and should represent a standard in the routine examination of dialytic patients. The training of PoCUS inexperienced students for the diagnosis of TR-CVCd is feasible but did not lead to a sufficient level of sensitivity.
ABSTRACT
Although sludge piles from drinking water treatment plants can contain harmful substances, in many countries, their disposal methods are still unregulated. Besides aluminum, which is a major constituent in these residues, many other contaminants-like trace metals-can be present and may result from the quality of the raw materials used for water treatment. The application of these chemicals for the treatment of drinking water can generate toxic sludge and contaminate the produced water. In the present work, mercury contamination in the sludge piles of two drinking water treatment plants located along the margins of the Juturnaíba Reservoir, Southeast Brazil, was evaluated to verify whether contaminants are incorporated during water treatment. In the summer 2012, five cores were collected from the piles, and were analyzed for Eh, granulometry, total carbon, total nitrogen, and total mercury. The results indicated an anoxic environment, reflecting composition of the suspended matter. Carbon and nitrogen presented elevated concentrations, but also seemed to reproduce the characteristics of the suspended matter in the raw water. The concentrations of mercury were extremely variable but presented unexpectedly high values in some of the layers, reaching 18,484 ng g-1. On the other hand, concentrations ten times lower than those observed in the natural system (8 ng g-1) could be observed. It was concluded that the only possible source for the contamination of the sludge was the chemicals used for water treatment.