Color Doppler ultrasound evaluation of arteriovenous grafts for hemodialysis.

Although arteriovenous fistula (AVF) continues to be the vascular access of choice for the hemodialysis, arteriovenous graft (AVG) can be the best choice in certain categories of patients and could have several advantages over AVF in a "patient centered approach" to vascular access. In the clinical management of prosthetic fistulas, color Doppler ultrasound (CDU) is the imaging method of choice for identifying stenosis and other AVG complications. In this review, besides highlighting the pivotal role of CDU in the diagnosis of AVG complications, we will underline the key role that ultrasound can play in identifying those stenosis most likely to cause AVG thrombosis. Furthermore, we will emphasize the support that CDU can play in distinguishing the different types of grafts and prosthetic devices such as stent-grafts, in identifying AVG with lower survival, CDU utilities and limitations in the evaluation of freshly-implanted grafts, the different sites available for AVG volume flow measurement and their use based on the configuration of the prosthesis, the time interval elapsed from the surgical intervention and the integrity of the prosthetic walls.

When Are Children Most Physically Active? An Analysis of Preschool Age Children's Physical Activity Levels.

The levels of physical activity (PA) in the population have decreased, especially at an early age. The aims of the study were: to evaluate the percentage of children meeting PA recommendations for both genders, and to measure steps and PA level at different time intervals during the week. This was an observational cross-sectional study. Seventy-three schoolchildren (36 boys and 37 girls), aged two years (2.12 ± 0.46), were selected to participate in this study. Participants wore an "Actigraph GT3X" accelerometer for seven days to measure the minutes engaged in moderate-to-vigorous physical activity (MVPA) and step volume. The results show 100% of the children studied met the recommended 60 min/day of MVPA, and 50% achieved 120 min/day MVPA and 13,000 steps per day. No gender differences were found. The results of the analysis show a propensity for higher step volumes and PA values from Monday to Friday. In addition, subjects achieved higher step volumes and PA values during "School Time" than "Out-of-School Time". Given that during "School Time" children showed higher PA and step values, schools represent an important place to help facilitate PA milestones. This study shows the need for further studies and interventions aimed at understanding and improving children's PA levels at an early age.

[Assessment of correct positioning and complications after insertion of central venous catheters using chest radiography]. / La radiografia del torace nella valutazione del corretto posizionamento e delle complicanze del catetere venoso centrale.

The central venous catheter (CVC) is a very common procedure in the daily medical practice. In fact the CVCs are used to administer liquids and chemotherapeutics, the parenteral nutrition management, the measurement of the central venous pressure, the administration of hemodialysis. The international guidelines recommends always verifying the correct positioning of the tip of the CVC and to identify possible complications before his use. In the clinical practice the radiography of the chest represents the technique used more diffusedly for the control of the positioning and the possible precocious complications of the temporary and permanent CVCs positioned in the central veins. The integrated use of conventional radiology, above all digital of last generation, spiral computed tomography and ultrasounds allows to nearly have in every situation the answers for a correct diagnosis. The nephrologist, necessarily brought to deal with CVC, cannot refuse from a knowledge of such tools.

[Color-Doppler imaging and arteriovenous fistula: preoperative evaluation and surveillance]. / Eco-color-Doppler e fistola artero-venosa: utilizzo pre e post-chirurgico.

The native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because of the lower incidence of complications and longer survival in comparison to grafts and central venous catheters. The use of color-Doppler sonography in the surgery of vascular accesses has increased the number of patients that are eligible for AVF as it allows to optimize the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color-Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist. This aspect is undoubtedly an additional value. Here we present a survey of the applications of CDI in the surgery and followup of AVF, with particular reference to preoperative mapping, AVF maturation and surveillance.

[Use of ECG-EC in the positioning of central venous catheters]. / Elettrocardiografia endocavitaria nel posizionamento dei cateteri venosi centrali.

Central venous catheters (CVC) are widely used in clinical practice for the administration of chemotherapy, parental nutrition, hemodynamic monitoring, and hemodialysis. International guidelines have defined the right internal jugular vein as the preferred site of CVC insertion and underline that accurate positioning of the catheter tip is essential to maximize the blood flow and reduce long-term complications. Endocavitary electrocardiography (EC-ECG) improves the accuracy of catheter tip positioning without increasing the placement time by the recognition of typical P wave patterns during catheter insertion:the normally shaped P wave identifies the mid to upper superior vena cava, the widest P wave may be used to place the CVC tip at the superior vena cava-right atrium junction, and biphasic P waves identify the location of the right atrium. Because of its simplicity and safety, EC-ECG should always be considered during CVC placement, especially if other means of verifying correct CVC insertion are not available.