The Effect of Arterial Curvature on Blood Flow in Arterio-Venous Fistulae: Realistic Geometries and Pulsatile Flow.

Arterio-Venous Fistulae (AVF) are regarded as the "gold standard" method of vascular access for patients with End-Stage Renal Disease (ESRD) who require haemodialysis. However, up to 60% of AVF do not mature, and hence fail, as a result of Intimal Hyperplasia (IH). Unphysiological flow and oxygen transport patterns, associated with the unnatural and often complex geometries of AVF, are believed to be implicated in the development of IH. Previous studies have investigated the effect of arterial curvature on blood flow in AVF using idealized planar AVF configurations and non-pulsatile inflow conditions. The present study takes an important step forwards by extending this work to more realistic non-planar brachiocephalic AVF configurations with pulsatile inflow conditions. Results show that forming an AVF by connecting a vein onto the outer curvature of an arterial bend does not, necessarily, suppress unsteady flow in the artery. This finding is converse to results from a previous more idealized study. However, results also show that forming an AVF by connecting a vein onto the inner curvature of an arterial bend can suppress exposure to regions of low wall shear stress and hypoxia in the artery. This finding is in agreement with results from a previous more idealized study. Finally, results show that forming an AVF by connecting a vein onto the inner curvature of an arterial bend can significantly reduce exposure to high WSS in the vein. The results are important, as they demonstrate that in realistic scenarios arterial curvature can be leveraged to reduce exposure to excessively low/high levels of WSS and regions of hypoxia in AVF. This may in turn reduce rates of IH and hence AVF failure.

The effect of in-plane arterial curvature on blood flow and oxygen transport in arterio-venous fistulae.

Arterio-Venous Fistulae (AVF) are the preferred method of vascular access for patients with end stage renal disease who need hemodialysis. In this study, simulations of blood flow and oxygen transport were undertaken in various idealized AVF configurations. The objective of the study was to understand how arterial curvature affects blood flow and oxygen transport patterns within AVF, with a focus on how curvature alters metrics known to correlate with vascular pathology such as Intimal Hyperplasia (IH). If one subscribes to the hypothesis that unsteady flow causes IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto the outer-curvature of a curved artery. However, if one subscribes to the hypothesis that low wall shear stress and/or low lumen-to-wall oxygen flux (leading to wall hypoxia) cause IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto a straight artery, or the inner-curvature of a curved artery. We note that the recommendations are incompatible-highlighting the importance of ascertaining the exact mechanisms underlying development of IH in AVF. Nonetheless, the results clearly illustrate the important role played by arterial curvature in determining AVF hemodynamics, which to our knowledge has been overlooked in all previous studies.

Helping postpartum rural adolescents visualize future goals.

PIP: An Art Future Image (AFI) intervention was initiated among postpartum adolescent mothers during the hospitalization period in North Carolina. The aim was to improve adolescents self-image and encourage educational goal setting as a means of changing the cycle of poverty. The hope was that mothers would consider alternatives to public assistance. Nursing students were engaged as teachers during their clinical rotation in the postpartum unit. The project involved 9 mothers (8 Black women and 1 White woman). Women ranged in age from 17 to 24 years. 8 women were single, and all had a low socioeconomic status. Each study participant completed a workbook, which reflected future images as a high school or college graduate, an accountant, and other occupations. The study women selected a future role and spoke about their dreams and plans and constraints to achievement of their goal. Instant photos were taken of the mother and the infant following the interview and the faces placed on personalized body images of their choice. Both students and participants were enthusiastic about the project. An evaluation found, however, that time constraints of staff nurses would prohibit the use of this intervention model. The suggestion was made for this module to be incorporated into two 30 minute classes as part of postpartum classes. Mothers wanted only one time slot. Suggestions were made to expand the AFI program at other postpartum check-up times or when counseling on family planning. Other members of the family unit could be included. The long-term impact of AFI needs to be evaluated.^ieng

Nutriquest: a fun way to reinforce nutrition knowledge.

Gaming is an educational strategy that facilitates and reinforces student learning in a stimulating and dynamic format. The authors describe the creation and use of a nutrition review board game. The game, NUTRIQUEST, was used to reinforce the theoretical concepts of nutrition and the principles of dietary management.

Effective teacher characteristics identified by adult learners in nursing.

What characteristics should adult education nursing faculty use to get and maintain the attention and interest of learners? There is a dearth of research or literature available to guide nursing faculty in "grabbing" the learner's interest or attention. Thus, the outcome of this project identified 20 attributes as effective teacher characteristics perceived by learners. Further, these attributes were used to generate a checklist to enhance an educator's ability to hone in on salient characteristics desired by nursing continuing education learners. This checklist, "Be Prepared to Teach," will assist the educator to utilize both professional and personal characteristics perceived as effective by adult learners.

An hour of bright white light in the early morning improves performance and advances sleep and circadian phase during the Antarctic winter.

Previous work has demonstrated that exposure to an hour of bright light in the morning and the evening during the Polar winter has beneficial effects on circadian phase. This study investigated the effect of a single hour of bright white morning light on circadian phase, sleep, alertness and cognitive performance. Nine individuals (eight male, one female, median age 30 years), wintering at Halley Research Station (75°S), Antarctica from 7th May until 6th August 2007, were exposed to bright white light for a fortnight from 08:30 to 09:30 h, with two fortnight control periods on either side. This sequence was performed twice, before and following Midwinter. Light exposure, sleep and alertness were assessed daily by actigraphy, sleep diaries and subjective visual analogue scales. Circadian phase (assessed by urinary 6-sulphatoxymelatonin rhythm) and cognitive performance were evaluated at the end of each fortnight. During light exposure circadian phase was advanced from 4.97 ± 0.96 decimal hours (dh) (mean ± SD) to 4.08 ± 0.68 dh (p = 0.003). Wake-up time was shifted by a similar margin from 8.45 ± 1.83 dh to 7.59 ± 0.78 dh (p < 0.001). Sleep start time was also advanced (p = 0.047) but by a lesser amount, consequently, actual sleep time was slightly reduced. There was no change in objective or subjective measures of sleep quality or subjective measures of alertness. An improvement in cognitive performance was found with both the Single Letter Cancellation Test (p < 0.001) and the Digit Symbol Substitution Test (p = 0.026) with preserved circadian variation. These beneficial effects of a single short duration light treatment may have implications not only for the Antarctic but other remote environments where access to natural light and delayed circadian phase, is problematic. These results require validation in larger studies at varying locations.