NN&I - July 2010
National 12 Nephrology News & Issues July 2010Subscribe to our free eNewsletter at www.nephronline.comvascular access sites through planning, coordination of effort, and elective corrective intervention, rather than urgent procedures or replacement. That said, the evidence for a Conditions for Coverage mandate on surveillance is lacking. Anatole Besarab, MD Wayne State University Detroit Gerald Beathard, MD Lifeline Vascular Access Houston Donald Schon, MD (retired) Arizona Kidney Disease and Hypertension Center Phoenix References 1. Multiple authors. Is there a need to mandate access surveillance in the dialysis clinic? Neph News Iss, 2010; June: 29-30 2. Medicare and Medicaid Programs: Conditions for Coverage for End-Stage Renal Disease Facilities; Final Rule: Rules and Regulations, Part II, Department of Health and Human Services, Federal Register, vol 73, April 15, 2008 3. Ram SJ et al. A randomized controlled trial of blood flow and stenosis sur -veillance of hemodialysis grafts. Kidney Int. 2003;64:272 4. Moist LM et al. Regular monitoring of access flow compared with moni- toring of venous pressure fails to improve graft survival. J Am Soc Nephrol 2003;14:2645 5. Lumsden AB et al. Prophylactic balloon angioplasty fails to prolong the patency of expanded polytetrafluoroethylene arteriovenous grafts: results of a prospective randomized study. J Vasc Surg. 1997; 26:382 6. Dember LM et al. Randomized controlled trial of prophylactic repair of hemodialysis arteriovenous graft stenosis. Kidney Int 2006; 66: 390 7. Robbin ML et al. Randomized comparison of ultrasound surveillance and clinical monitoring on arteriovenous graft outcomes. Kidney Int. 2006;69:730 8. Martin LG et al. Prophylactic angioplasty reduces thrombosis in virgin ePTFE arteriovenous dialysis grafts with greater than 50% stenosis: subset analysis of a prospectively randomized study. J Vasc Interv Radiol 1999;10:389 9. Dossabhoy NR, et al. Stenosis surveillance of hemodialysis grafts by duplex ultrasound reduces hospitalizations and cost of care, Semin Dial 2005;18:550 10. Malik J et al. Regular ultrasonographic screening significantly prolongs patency of PTFE grafts. Kidney Int. 2005;67:1554 11. Tessitore N et al. Can blood flow surveillance and pre-emptive repair of subclinical stenosis prolong the useful life of arteriovenous fistulae? A ran-domized controlled study. Nephrol Dial Transplant. 2004; 19:2325 12. Besarab A, Sullivan KL, Ross R, Moritz M. The Utility of intra-access moni- toring in detecting and correcting venous outlet stenoses prior to thrombosis. Kidney Int. 47: 1364-1373, 1995 13. Zasuwa. G et al. Non-invasive derived intravascular access pressure sur -veillance reduces thrombosis rate. Seminars Dial 2010 [In print] 14. Sackett DL et al. Evidence based medicine: what it is and what it isn't. BMJ 1996; 312:71The authors' response Besarab et al. do not support a CMS surveillance require-ment. Nevertheless, in their opinion, surveillance does reduce access thrombosis. They argue that randomized controlled trials (RCTs) looking at surveillance have had inadequate sample sizes. Also, physical examination of accesses is not generally done. Thus, without surveillance, nothing will be done to maintain accesses. Is surveillance better than nothing? Based on how surveillance is usually practiced (one blood flow or derived static venous pressure (VP) measurement/month), no. Hemodynamic variation is large during dialysis, causing many false positive and false negative indications of stenosis. Also, stenosis often pro-gresses rapidly, and mathematical modeling has shown that flow or VP may change so rapidly that the change will not be detected before thrombosis. Thus, monthly surveillance does not accurately predict thrombosis.1,2 In a study of 1,957 flow measurements in 176 patients, flow predicted graft thrombosis with a sensitivity of only 53% at a false positive rate of 21%.2 Thus, a high sensitivity requires a high false positive rate that likely yields many unnecessary interven -tional procedures. Moreover, angioplasty causes an injury to the access that stimulates neointimal hyperplasia,3 so that angioplasty of stable stenotic lesions is probably harmful. Surveillance might improve outcomes if measurements were taken more frequently. This would allow calculation of average values that neutralize hemodynamic variation, and would make it easier to detect rapid changes in flow or VP before thrombosis. Unfortunately, no RCTs have taken this approach. Moreover, flow measurements take significant time, so it is probably impractical to increase measurement frequency. However, online methods are available that facil- itate frequent VP measurements. Standard monthly surveil -lance may not be better than doing nothing, and may even be harmful. Multiple VP measurements/month might be a successful approach. More direct visualization of stenosis by duplex ultrasound might also be successful. However, until properly designed studies are done, these are just speculations. William D. Paulson, MD Charlie Norwood VA Medical Center Medical College of Georgia, Augusta, Ga. References 1. Paulson WD, Work J. Controversial vascular access surveillance mandate. Sem Dial 23: 92-94, 2010 2. Ram SJ, et al. Risk of hemodialysis graft thrombosis: Analysis of monthly flow surveillance. Am J Kidney Dis 52: 930-938, 2008 3. Chang CJ, et al. Highly increased cell proliferation activity in restenotic hemodialysis vascular access after percutaneous transluminal angioplasty. Am J Kidney Dis 43: 74-84, 2004 National_NNI0710_7.indd 12 6/16/10 2:34:06 PM
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