Alan Dubrow

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.

The Changing Spectrum of Heroin-Associated Nephropathy

Thirty-five renal biopsies were performed on heroin abusers at our institution between January 1977 and June 1983 as part of the evaluation of unexplained heavy proteinuria. Twenty-eight patients (80%) had histopathologic diagnoses of either focal segmental glomerulosclerosis or renal amyloidosis. Patients having a diagnosis of renal amyloidosis were older (P = 0.025), had a longer history of heroin abuse (P = 0.05), and 13/14 demonstrated clear evidence of chronic subcutaneous suppurative lesions. The remaining seven patients demonstrated a spectrum of disease similar to that seen in the nonaddicted population. We compared the clinical and biopsy characteristics of patients evaluated between 1977 and 1980 with those seen between 1981 and 1983. The relative incidences of renal amyloidosis and focal glomerulosclerosis changed significantly (P = 0.025). Whereas 29% of patients in the early series had renal amyloidosis and 57% had focal glomerulosclerosis, the relative incidences in the later series were 48% and 29%, respectively. The development of renal amyloidosis in our patients appears to be related to a longer duration of heroin abuse with increased incidence of subcutaneous injection of the narcotic. Chronic, suppurative skin ulcerations tend to occur at the site of injection, resulting in a persistent acute-phase inflammatory state important for the initiation and potentiation of secondary amyloidosis.

Epoprostenol (PGI2, prostacyclin) during high-risk hemodialysis: preventing further bleeding complications.

The frequency of hemodialysis‐associated hemorrhage was studied prospectively in two successive, parallel, heparin‐controlled studies using epoprostenol (PGI2; average dose, 4.1 ng/kg‐min) as the sole antithrombotic agent. Sixty‐three patients with active or recently active Weeding underwent 163 hemodialysis treatments in each of which prospective Weeding risk was assessed. PGI2 was associated with up to 50% overall reduction in the frequency of Weeding, particularly in the highest risk circumstances. PGI2 also allowed successful completion of the full, prospectively prescribed hemodialysis time in the most treatments (82% versus 93% with heparin). Furthermore, the efficiency of hemodialysis using PG12, as indicated by the reduction in concentration of blood urea nitrogen and serum creatinine, was equal to that using heparin, even though there was a tendency toward modest reduction in residual volume of the hollow fiber dialyzer and slightly more frequent early termination of treatment from dialyzer clotting with PGI2. No severe vasodilatory side effects of PGI2 were observed during these studies. Hypotension was equally frequent during hemodialysis with heparin as with PGI2. The current results suggest that PGI2 should be considered as a substitute for heparin during high‐risk hemodialysis because PGI2 may reduce the incidence of dialysis‐associated Weeding without severe adverse side effects.

Interventional Nephrology and Dialysis: Continuous Flow Peritoneal Dialysis: Principles and Applications

Continuous flow peritoneal dialysis (CFPD) is a technique of renal replacement therapy (RRT) dating back to the 1960s. Its essential features are a fixed intraperitoneal volume and rapid, continuous movement of dialysis solution into and out of the peritoneal cavity. Inlet and outlet catheters and a means of generating a large volume of sterile dialysate are required. External regeneration of dialysate via conventional hemodialysis (HD) equipment or sorbent technology mitigates the need for large volumes of sterile fluid and makes the technique feasible. Clearance depends on the peritoneal mass transfer coefficient, rate of dialysate flow, and efficiency of external regeneration. Studies to date all demonstrate small solute clearances three to eight times greater than conventional automated peritoneal dialysis (PD). Catheter design is crucial to the clinical success of the technique and will be discussed. Potential applications include daily home dialysis, treatment of acute renal failure in the intensive care unit (ICU), and ultrafiltration of ascites. Clinical experience with the latter will be presented in detail.

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).

The 2006 K/DOQI Guidelines for Peritoneal Dialysis Adequacy Are Not Adequate

The 2006 National Kidney Foundation K/DOQI guidelines have lowered the peritoneal dialysis adequacy standard of Kt/Vurea from 2.1 to 1.7 in anuric patients, largely based on the patient survival results of 2 clinical trials in Mexico and Hong Kong. It is our contention that the guidelines may be misleading since they have chosen to ignore the bias in these trials and have ignored the adverse outcomes in control groups in the trials on which the guidelines are based, as well as the body size of the subjects in these trials. Body size has changed in the US and Canada over the last few decades and there are similar changes worldwide. We suggest that the minimum targets for peritoneal dialysis be reinstituted at the previous standard Kt/Vurea of 2.0.