Electrospun fiber - Hydrogel composites for nucleus pulposus tissue engineering

New materials are needed to replace degenerated intervertebral disc tissue and to provide longer-term solutions for chronic back-pain. Replacement tissue potentially could be engineered by seeding cells into a scaffold that mimics the architecture of natural tissue. Many natural tissues, including the nucleus pulposus (the central region of the intervertebral disc) consist of collagen nanofibers embedded in a gel-like matrix. Recently it was shown that electrospun micro- or nano-fiber structures of considerable thickness can be produced by collecting fibers in an ethanol bath. Here, randomly aligned polycaprolactone electrospun fiber structures up to 50 mm thick are backfilled with alginate hydrogels to form novel composite materials that mimic the fiber-reinforced structure of the nucleus pulposus. The composites are characterized using both indentation and tensile testing. The composites are mechanically robust, exhibiting substantial strain-to-failure. The method presented here provides a way to create large biomimetic scaffolds that more closely mimic the composite structure of natural tissue. © 2012 Materials Research Society.

Guidewire retention following central venous catheterisation: a human factors and safe design investigation.

BACKGROUND: Central Venous Catheterisation (CVC) has occasionally been associated with cases of retained guidewires in patients after surgery. In theory, this is a completely avoidable complication; however, as with any human procedure, operator error leading to guidewires being occasionally retained cannot be fully eliminated. OBJECTIVE: The work described here investigated the issue in an attempt to better understand it both from an operator and a systems perspective, and to ultimately recommend appropriate safe design solutions that reduce guidewire retention errors. METHODS: Nine distinct methods were used: observations of the procedure, a literature review, interviewing CVC end-users, task analysis construction, CVC procedural audits, two human reliability assessments, usability heuristics and a comprehensive solution survey with CVC end-users. RESULTS: The three solutions that operators rated most highly, in terms of both practicality and effectiveness, were: making trainees better aware of the potential guidewire complications and strongly emphasising guidewire removal in CVC training, actively checking that the guidewire is present in the waste tray for disposal, and standardising purchase of central line sets so that differences that may affect chances of guidewire loss is minimised. CONCLUSIONS: Further work to eliminate/engineer out the possibility of guidewires being retained is proposed.