Abstract
Although ultrasound is useful as an adjunctive method for diagnosing peritoneal dialysis catheter tunnel infection, precise ultrasound images of catheters have not been published. In order to obtain precise ultrasound images and clarify scanning techniques, a simulation study was performed. To simulate a catheter without infection, a catheter was placed horizontally in a gelatin simulator and observed using an ultrasound machine with a linear probe. The tube of the catheter was visualized as four dots or arches with a short-axis view, and four parallel lines with a long-axis view. The cuff of the catheter was visualized as a hyper-echoic crescent with a short-axis view, and a bold line with a long-axis view with a prominent acoustic shadow beneath it. To simulate tunnel infection, a layer of water was added around the catheter, creating a surrounding hypo-echoic area. When the probe was angled at approximately 12 degrees, the hypo-echoic area became almost unidentifiable. The area, however, became visible again by adjusting the ultrasound beam to be perpendicular to the catheter with a short-axis view. Similar findings were observed in patients with or without tunnel infection. As detecting any hypo-echoic area around the catheter is crucial for the sonographic diagnosis of tunnel infection, it is necessary to adjust the angle of the ultrasound probe with a short-axis view. Although further reports should be accumulated to determine the sonographic criteria for tunnel infection, the simulation was useful for clarifying basic ultrasound images of the peritoneal dialysis catheter.
