Both the routine and selective use of preoperative duplex ultrasound for planning hemodialysis access have been associated with an increase in the use of autogenous accesses relative to the various institutional experiences pre-DOQI. Although the anatomic criteria for defining a suitable vein conduit and preferences for access location/configuration vary somewhat between reports, the techniques of noninvasive testing and imaging remain similar. Our protocol was developed at the University of South Florida in 1998 and is described below. In addition to the existing CPT code (93990) for duplex imaging of functioning prosthetic and autogenous accesses, a new code (G0365) has been created in 2005 for pre-operative vessel (arterial and venous) mapping before first-time construction of a fistula in a limb without prior access creation. Consistency of reimbursement for use of this code remains to be determined.

The noninvasive testing should be performed in a warm room and begins with an upper-extremity arterial study using continuous wave Doppler ultrasound and selected blood pressure measurements. Notably, the nondominant extremity is used preferentially due to the small but real potential to compromise the dominant hand by the ultimate access procedure. Brachial artery pressures are measured and the corresponding velocity waveforms at the brachial (antecubital), radial (wrist), and ulnar (wrist) arteries recorded. Formal blood pressure measurements in the radial and ulnar arteries are not obtained due to the frequent presence of calcification within the vessel wall that precludes accurate assessment. A photoplethysmographic (PPG) waveform and pressure are recorded for the third digit using the appropriate sensor and a digital cuff, respectively. A pressure gradient of ≥15 mmHg between the brachial arteries and/or the absence of a triphasic velocity waveform (at the brachial artery) suggest a hemodynamically significant inflow stenosis. Similarly, a pressure gradient of ≥30 mmHg between the ipsilateral brachial artery and the third digit and/or a diminution in the corresponding velocity waveforms suggests the presence of significant occlusive disease distal to the antecubital fossa (outflow). An Allen test is performed to assess the relative contributions of the radial and ulnar artery to the digital/palmar perfusion using the digital PPG waveform. Further noninvasive testing beyond this point is only performed if there is no evidence of hemodynamically significant arterial occlusive disease in the inflow/outflow vessels and the absolute digital pressures exceed 80 mmHg. Notably, these strict criteria were imposed in an attempt to reduce the incidence of postoperative hand ischemia or the “steal” phenomenon. Arterial testing is completed with transverse imaging of the
distal radial and brachial arteries using a high-resolution duplex scanner (Philips/ATL HDI 3000 or 5000, Bothell, WA) and L 7-4 MHz or CL 10-5 MHz transducer probe. An arterial diameter of ≥2.0 mm without extensive calcification is considered adequate as the inflow site for the access (Fig. 83-1).

Venous duplex imaging of the central veins is then performed on the arm deemed suitable for an autogenous access based upon the arterial studies. The patient is positioned supine on a stretcher with head elevated while the arm is extended and placed on a pillow. The subclavian, brachial, and axillary veins are evaluated for both acute and chronic venous obstruction using color duplex imaging (L 7-4 MHz probe) and the standard augmentation maneuvers. The internal jugular vein is examined in patients with a previous, ipsilateral dialysis access catheter and those with abnormal studies in the axially/subclavian vein. The contralateral upper extremity is examined in patients with a suspected central venous stenosis (Figs. 83-2 and 83-3).

The superficial veins (cephalic and basilic) of the forearm are examined using a CL 10-5 MHz transducer in the extremity deemed acceptable based upon the arterial and central venous studies. Starting at the wrist and moving cephalad, the veins in the forearm are evaluated at multiple sites (usually 3 to 4 different sites). The examination includes determination of the diameter (outer wall to outer wall on transverse imaging) and depth beneath the skin, in addition to an assessment of compressibility and quality (wall thickening and fibrosis). Wrapping the extremity in a warm towel, having the patient perform repetitive hand exercises, and/or applying a tourniquet below the antecubital fossa, may augment the venous distention and facilitate identification of the veins that lie deep to the skin. Vein diameters of ≥2.5 mm are considered adequate for autogenous access construction. The segments of the cephalic and basilic veins spanning the antecubital fossa are then examined for the forearm veins that are deemed adequate. This occasionally necessitates moving the tourniquet more proximal on the arm. The superficial veins in the arm or upper arm (i.e., cephalic to the deltopectoral groove, basilic to its axillary confluence) are similarly examined if the forearm veins are <2.5 mm. If no suitable superficial vein is identified in the nondominant arm, then the contralateral arm is studied, presuming the results of the arterial and central vein studies are acceptable (Figs. 83-4 and 83-5). A summary of our noninvasive arterial and venous criteria for selecting suitable locations for autogenous accesses is shown in Table 83-1.