CQI: hemodialysis vascular access flow monitoring

One of the main ongoing challenges in nephrology is maintaining a good, well-functioning vascular access. Vascular access problems lead to complications such as access recirculation causing decreased adequacy of dialysis as shown by kinetic modelling and access clotting. Access flow measurement using ultrasound dilution technique is an accurate and better indicator of impending access stenosis than recirculation (urea method). The measurement is non-invasive, the procedure simple, and the monitor accessible at the bedside. The Adam Linton Dialysis Unit of the London Health Sciences Centre, Victoria Campus is currently monitoring access flows (Qa) as a continuous quality initiative using ultrasound dilution technique. Access recirculation (AR) is determined and Qa measurements are done bimonthly on all chronic in-centre and self-care dialysis patients with either arteriovenous fistula or Gore-tex grafts. Qa's of <550 ml/min or 20% decrease in flows are investigated by angiography and early intervention is instituted either by angioplasty or fistula repair. Our unit's goal is to be proactive in our investigation and in our nursing and medical interventions. From our experience, the problem with responding to poor clearances by checking for recirculation after the fact is that valuable time is lost for proactive intervention to preserve the access site and may in fact be too late. In four different patient situations we are able to show how our different interventions have improved Qa's and eliminated AR resulting in increased Kt/V. The intent of this article is to show that Qa measurement can be an ideal way to monitor hemodialysis vascular accesses over time. It provides a means to detect impending access dysfunction before the Qa has decreased enough to have induced AR and/or under-dialysis. By early intervention, optimum dialysis efficiency is achieved and the prescribed Kt/V [urea] is delivered.