4.1 Monitoring the access:
- 4.1.1 Access patency should be ensured before each treatment before any attempts to cannulate the access.
- 4.1.2 All caregivers, including fellows in training, should learn and master the methods for examining a vascular access.
- 4.1.3 Access characteristics, such as pulsatility and presence of thrill, as well as flow and pressure, should be recorded and tracked in a medical record and be available to all caregivers of the VAT.
4.2 Frequency of measurement is dependent on the method used:
- 4.2.1 It is not clear that access flow measurements performed at a monthly frequency provide sufficient data stability to make decisions. Until additional studies are performed to determine the optimal frequency, more frequent measurements are recommended.
- 4.2.2 Static pressure measurements require less technology and should be made more frequently than flow measurements. Direct measurements of static pressure ratios should be made every 2 weeks. Less-direct measurements should be made weekly. Dynamic pressures, if used (see CPG 4.2.3), should be measured with each dialysis treatment, but derivation of a static pressure should be attempted, rather than using the raw numbers.
- 4.2.3 Measurement of recirculation is not recommended as a surveillance technique in grafts.
4.3 Frequency of measurement for access complications:
- 4.3.1 Thrombosis in fistulae develops more slowly than in grafts. Flow measurements performed at a monthly frequency appear to be adequate. Until additional studies are performed to determine the optimal frequency, less frequent measurements are not recommended.
- 4.3.2 Because static pressure measurements are inherently less accurate in detecting access stenosis in fistulae, the frequency should not be less than in grafts. Direct measurements of static pressure ratios should be made every 2 weeks. Less-direct measurements should be made weekly. Dynamic pressures should be measured with each dialysis. Increased recirculation can indicate reduced effective blood pump flow, resulting in inadequate dialysis.
4.4 Diagnostic testing:
- 4.4.1 Characteristics of access (see CPR 4.1), as well as blood pump flow and pressure performance, should be recorded and tracked in medical records.
- 4.4.2 Data should be analyzed at least monthly to evaluate access dysfunction.
- 4.4.3 After intervention, the surveillance parameter should be restored to normal.
- 4.4.4 Data should be analyzed to improve success rates and ensure that interventions are appropriately assessed. For example, PTA and surgical revision rates, recurrence rates, and number of procedures per patient year should be systematically analyzed in a CQI process.
- 4.4.5 A multidisciplinary team should be involved.
- 4.4.6 Preemptive correction of hemodynamically significant stenoses should remain the standard of care.
There is considerable debate concerning whether PTA interventions improve long-term outcomes. Until sufficiently powered clinical studies are performed, the rationale for monitoring and surveillance are provided in CPG 4. It is the belief of the Work Group that physical examination and clinical evaluation are forgotten skills that, if restored, could be as valuable as any surveillance method.
The utility of any method develops on sequential assessment and evaluation. This requires collection and storage of observations and/or data. Because stenoses evolve over time, observations and data should change over time. Because observers may change, data must be available to all caretakers.
Quality and outcome improvement cannot be determined without analyses of data.