Frank R. Prosl

Adjunctive antibiotic/anticoagulant lock therapy in the treatment of bacteremia associated with the use of a subcutaneously implanted Hemodialysis Access device

To improve vascular access for hemodialysis, a new device (Dialock Hemodialysis Access System, Biolink Corporation, Middleboro, MA) has been developed. Implanted subcutaneously, the device is accessed by percutaneous puncture. Attached to the device are two catheters that are implanted into the superior vena cava or right atrium. Clinical results thus far have been promising. However, use of this device is not free from infectious complications. In the present pilot study, 25 maintenance hemodialysis patients were implanted with 26 Dialock devices. The incidence of bacteremia was 2.9/1,000 catheter days. In 14 episodes of bacteremia in 8 patients the infection was successfully treated with a combination of systemic antibiotic treatment and adjunctive antibiotic/anticoagulant lock therapy. The lock therapy entailed the instillation of both an antibiotic and an anticoagulant into the device. We believe that the antibiotic/anticoagulant lock technique is an effective, adjunctive therapeutic modality in the treatment of infections related to the use of indwelling vascular access devices.

NEW ACCESS DEVICE FOR HEMODIALYSIS

A new subcutaneous device (Dialock; Biolink Corp., Middleboro, MA) provides vascular access to patients who currently require hemodialysis (HD). The device consists of a port-like valve, implanted subcutaneously below the clavicle, which provides a linear flow passage to two catheters placed in the right atrium via the jugular vein. The valve is accessed percutaneously with needle-cannulas that functionally convert the device to twin catheters for connecting the patient to the HD lines. Interdialytic patency is maintained using a standard heparin lock. The device has been implanted in 10 outpatients under local anesthesia, with almost immediate use for HD (median, 3 days) and has functioned successfully for more than 6 months (mean +/- SD, 4.0 +/- 1.7; > 400 dialysis sessions). Blood flows over 300 ml/min were consistently achieved (average, 320 +/- 50) with venous and arterial pressures of 197 +/- 42 mmHg and -241 +/- 31 mmHg, respectively. After 40 patient-months, condition of the needle puncture sites remains satisfactory. Four systemic infections have occurred in three patients; all have resolved without the need for device removal. There have been no infections at the puncture sites. One patient whose heparin lock was not changed for 23 days (for reasons unrelated to the device) required fibrin sheath stripping of his catheters. Patient and nurse acceptance has been excellent. The device may offer substantial improvement over conventional devices for HD access.

Dialock: Pilot Trial of a New Vascular Port Access Device for Hemodialysis

Vascular access (VA), an essential tool for end stage renal disease (ESRD) patients, remains a weak component of extracorporeal renal replacement therapy (RRT) (1, 2). VA related problems are the primary cause of hospitalization accounting for most of the morbidity cost in ESRD patients (3, 4). Native and/or prosthetic arteriovenous fistulas (AVF), considered the “gold standard” for permanent VA in dialysis, have some limitations (5, 6). AVF may not be functional or usable on short notice in newly recruited or late referred ESRD patients (7). Dysfunction of mature AVF may occur for several reasons: stenosis; thrombosis; low flow or high recirculation. AVF may also be contraindicated in patients with severe heart failure or peripheral arteritis (8). Infection is another condition that compromises the use of native or prosthetic AVF. Permanent catheters, proposed as an alternative to AVF in these conditions (9, 10), are associated with a significantly higher risk of infection (11–16). Whatever the causes of catheter infection (patientor staff-related), one of the main predisposing factors is the external location of the catheter. First, the catheter breaks the skin integrity and facilitates the migration of bacteria in the subcutaneous tunnel. Second, the catheter gives a permanent access to blood stream facilitating the bacteria contamination and migration from the internal lumen. Third, the tubing is made of synthetic elastomer, a foreign material facilitating the adhesion and the proliferation of bacteria (17, 18). A totally implantable device, in keeping with the permanent port concept, appears highly desirable. It has been shown that the VA port used for chemotherapy significantly reduced the risk of infection (19). To satisfy blood flow requirements of extra-corporeal renal replacement therapy (high flow, low resistance) a new subcutaneous port device (Dialock®) has been developed (20). This hemodialysis VA device consists of a metallic port-like valve implanted subcutaneously in the chest area and connected to a dual silastic right jugular vein catheter. This study reports additional results of the international pilot trial clinical trial with the Dialock hemodialysis access device (21).

New Hemodialysis Access System

A new blood access system for hemodialysis (HD) addresses the major shortcomings of current accessing techniques and helps overcome patient adversity with available choices. The system uses new methods, devices and compositions comprising several novel elements: (1) totally implanted port, elementally simple in design, small and robust with improved safety features, (2) engineered transcutaneous tissue tract (TTT) to precisely guide a tubular conduit to engage the implanted port, (3) viscoelastic gel prophylaxis for internal passages and surface interfaces of the port and TTT, (4) the tool kit aligns the TTT with the port and initiates TTT formation at the time of port placement, (5) an integrated external bloodline circuit comprising the interface between the implanted port and HD machine which can be reused for several treatment sessions. The system provides bloodless, painless, and fail-safe connections with redundant sealing along the complete blood path. It is substantially more robust than current access options and more convenient to use. TTT construct is durable, permanently aligned and fixed to the port enabling non-compromised tissue integrity during access penetration. A bullet-pointed tubular assembly enters and passes through the TTT confining the tubular device to advance towards the port and entering it to engage a solid tactually sensed stop indicating the correct position. The system may be used within a few days of port placement. The access is unobtrusive and preserves patient self-image.