Abstract
A stethoscope can be to evaluate arteriovenous access (AVA) to determine flow and the presence of stenosis. However, the usefulness and limitation of this approach have not been fully investigated. We used a simple method of auscultation to examine AVA. The chest-piece of the stethoscope was removed, and we listened to an AVA using the tip of the tube placed perpendicularly on the skin. We called this maneuver, the “tube auscultation method”, and compared the bruit of AVA obtained by this new method with that by the conventional method using an ordinary stethoscope. A fast Fournier transform was used to evaluate differences of the bruit. In an AVA with mild upstream stenosis, a low-pitched bruit was audible throughout the entire length of the vein, but it was difficult to detect the stenotic site by the conventional auscultation method. In contrast, using the tube auscultation method, a remarkable change in the pitch of the bruit was detected. The pitch of the bruit rose at the stenotic site, and gradually decreased beyond the stenosis. In a pulsating AVA with severe downstream stenosis, low-pitched bruit was heard along the entire length of the vein by the conventional method. Using the tube method, localized bruit was heard at the point of venous stenosis. The retrograde spread of bruit from the downstream stenotic site was the origin of the bruit heard with the conventional auscultation method. This retrograde spread of bruit could be eliminated with the tube method. We could localize stenosis exactly with the tube auscultation, but sometimes not with the conventional stethoscope. The tube auscultation method is a simple, inexpensive and very useful method for the examination of AVA.
