title: The value of noninvasive testing before and after hemodialysis access in the prevention and management of complications.
abstract: The relative value of and selective indications for specific applications of noninvasive testing and imaging in hemodialysis access patients are reviewed. Preoperatively, clinical arterial assessment, including an Allen's test, should be done routinely. This should be augmented by interrogating the ulnar and radial arteries with a Doppler probe, using collateral compression testing, in complex cases, particularly in patients with a history of previous failed fistulas or radial artery cannulations for blood pressure or blood gas monitoring. Vein mapping, using a duplex scan, is valuable in any patient in whom the superficial veins are not easily visible and distend nicely with tourniquet application. Patients who have previously had chronic cannulation of the subclavian or jugular veins, for hemodialysis or other reasons, should have proximal venous outflow obstruction ruled out by a duplex study. Postoperatively, baseline and serial noninvasive monitoring of the arteriovenous fistula (AVF) or shunt cannot be justified as a routine, but study is indicated if a thrill over the venous outflow cannot be detected postoperatively, veins do not become progressively distended after creation of a fistula, or good flows cannot be achieved during hemodialysis. However, in current practice, a dysfunctional, failing, or failed fistula or shunt is usually identified by the observations of the dialysis technician, and the patient is directly referred to the angiography suite, not the vascular diagnostic laboratory. The true identity and extent of such local complications as hematoma, seroma, abscess, cellulitis with phlegmon, or pseudoaneurysm may be difficult to define without the help of ultrasound imaging, which also can direct diagnostic aspiration. Finally, noninvasive testing, consisting of monitoring digital pressures and plethysmography, and their response to compression of the fistula, its venous outflow, the feeding artery proximally and distally, and the companion artery, is a key initial step in evaluating patients with disabling hand symptoms, distinguishing distal steal from focal ischemia, or, by elimination, pointing to venous congestion or secondary carpal tunnel syndrome.
authors.affiliation: Department of Surgery, University of Colorado School of Medicine, Boulder, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Rutherford
mesh_terms: D003955:Diagnostic Tests, Routine / Q000379:methods*; D006801:Humans; D011183:Postoperative Complications / Q000517:prevention & control*; D006435:Renal Dialysis / Q000009:adverse effects; D012680:Sensitivity and Specificity