Sentinel vascular access monitoring after endovascular intervention predicts access outcome

Reassessing the utility of access recirculation and Kt/V for the prediction of arteriovenous fistula failure using online clearance monitoring: the SHUNT STUDY

BACKGROUND

The arteriovenous fistula (AVF) is prone to thrombosis which can be avoided by use of monitoring and surveillance programmes. Although surveillance imaging techniques have been shown to be more sensitive and specific than clinical monitoring during dialysis, monitoring may have significant advantages in terms of cost and time saving. In this study we evaluate the yield of two monitoring techniques [blood temperature monitoring (BTM) access recirculation (AR) and Kt/V via online-clearance-monitoring (OCM)].

METHODS

In this single-centre prospective observational study, 101 patients were followed-up for one year. The primary outcome measure was a composite of AVF failure. OCM-Kt/V and BTM-AR were recorded at every dialysis session.

RESULTS

Of all baseline characteristics only a prior history of percutaneous transluminal angioplasty (PTA) to the AVF conferred a significant change in AVF survival (failure events/100 pt years with prior PTA vs. without = 64.0 vs. 17.3, log-rank p = 0.0014; unadjusted hazard ratio (HR) 3.74 (95% CI 1.56-8.94) p = 0.003). Participants with baseline AR < 10% vs. > 15% had poorer AVF survival (p = 0.0002) and HR for baseline AR 10-15% group vs. AR > 15% group = 4.5 (95% CI 1.55-13.05). There was no combination of change in (Δ) AR, ΔKt/V or its presence over any number of dialysis sessions that provided an acceptable combination of sensitivity and specificity or discrimination for AVF failure.

CONCLUSIONS

BTM-AR and OCM-Kt/V are specific but insufficiently sensitive tools for the prediction of AVF failure. BTM-AR and OCM-Kt/V use at every dialysis session appears to add little to the traditional, infrequent use of these evaluations.

Getting the basics right: the monitoring of arteriovenous fistulae, a review of the evidence

PURPOSE OF REVIEW

Despite being the preferred vascular access for haemodialysis, the arteriovenous fistula (AVF) remains prone to a number of complications, the most common of these being thrombosis secondary to stenosis. This has resulted in the widespread use of monitoring and surveillance programmes. Surveillance uses more resources than monitoring and has not been convincingly shown to improve outcomes. The evidence supporting the use of the various monitoring tools has been relatively neglected and has not been the focus of literature review. This narrative review is the first to appraise the evidence for the use of physical examination, access recirculation, Kt/V and dynamic venous pressures (DVP) as monitoring tools in mature AVF.

RECENT FINDINGS

The vastly increased number of data points for access recirculation, Kt/V and DVP produced as standard by online clearance monitoring (OCM) on modern dialysis machines is likely to have significantly changed the utility of these metrics in the prediction of AVF failure. Algorithms have been developed to highlight those of highest risk of failure.

SUMMARY

The evidence supporting the use of monitoring in the prediction of AVF failure is predominantly observational, underpowered and more than 20 years old. Access recirculation and Kt/V appears to have higher utility in AVF than in arteriovenous grafts. We suggest that the development of OCM necessitates the reevaluation of these tools.