The Dialock device offers a new and interesting vascular access alternative for haemodialysis bridging the 'gap' between permanent catheters and arteriovenous fistulae. Dialock's place in the vascular access strategy for haemodialysis patients deserves further long-term clinical studies.

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 Infusaid implantable infusion pump with a single delivery rate has maintained chronic intravenous heparin infusion in man for greater than 35 mo and for greater than 5 yr in the dog. Intra-arterial infuson of fluorodeoxyuridine has been maintained for greater than 8 mo in man. In a pilot study using a commercially available, transcutaneously controllable, magnetically activated valve for baseline superimposed bolus insulin infusion, the feasibility of maintaining near normal serum glucose in diabetic dogs was demonstrated. The effect of long-term intravenous cannulation was investigated; it was found that the intimal tissues of the vena cava surrounding the cannulae were largely unaltered and microemboli could not be detected in the lungs of the animals studied. Cannula plugging, which occurred on several occasions due to thrombus formation in the final centimeter of the cannula, has been solved by changes in pump design and refilling procedures. The problem of insulin precipitation in flow passages of the pump remains unsolved, but there are indications that substances entering the cannula from the blood may be involved. A new pump design for modulated insulin infusion is described.

The device represents a positive improvement in the area of HD access.