Blood pressure control in dialysis patients: importance of the lag phenomenon.

Failure by the world dialysis community to understand and use the dry-weight method of blood pressure (BP) control has resulted in an increasing incidence of treatment-resistant hypertension, which remains the principal cause of cardiovascular morbidity and mortality. This failure may in part be because the relationship between the extracellular volume (ECV) and BP is not simple and linear, but complex, because of a lag of several weeks between the normalization of the time-averaged ECV and the decrease in BP. Another cause for this failure may be the unwillingness to taper and stop all antihypertensive medications during the transition from hypertension to normotension. In this report, we describe in detail the lag phenomenon, document its presence during treatment in other populations, and describe how this knowledge is used in the application of the dry-weight method of drug-free BP control in the dialysis population.

Hypertension and a digoxin-like substance in the plasma of dialysis patients: possible marker for a natriuretic hormone.

Maintenance hemodialysis patients were randomly assigned to two groups based on the presence or absence of predialysis hypertension. Clinical profiles of the patients in the two groups were comparable except that there were more Blacks in the hypertensive group and that all the patients in this group received antihypertensive medications. Despite not taking any digitalis preparations, 10 of 12 hypertensives had measurable digoxin-like immunoreactive substance (DLIS) in their plasma. None of the 11 normotensives had detectable DLIS. Significantly higher (p less than 0.03) systemic vascular resistance was noted in hypertensives with DLIS compared to normotensives and hypertensives without DLIS. We propose that DLIS itself may be or may represent a marker for some vasopressive substance, possibly natriuretic hormone.

Long-term blood access by catheters implanted into arteriovenous fistulas of sheep.

Reliable long-term blood access in sheep was provided by implanting one or two catheters into the high velocity blood flow in the vein draining an arteriovenous fistula created in the neck. Thrombosis of the catheterized vein occurred in only one of 31 cases in which a catheter with rounded intravascular tip was used, as compared with seven in 10 cases using a sharp-tipped catheter. The mean duration of placement for all rounded-tip catheters was 228.6 days. Extrusion from the vessel occurred with 3 of 8 short catheters (2 cm intravascular length), but only after a period of more than seven months of implantation. Using a program of trice-weekly disinfection of the skin exit site, exterior portion of the catheter, and catheter lumen resulted in failure of only two catheters due to infection. Rounded-tip catheters with 5 cm intravascular length had 75% life table functional rate at 15 months. Implantation of two catheters permitted extracorporeal circulation at flows of up to 300 ml/min using a blood pump to withdraw blood from one catheter while simultaneously returning it through the second.

Subjective assessment of patient outcomes of home parenteral nutrition.

The medical, financial and psychosocial impact of home parenteral nutrition (HPN) therapy on patients' lives was assessed. A questionnaire that solicited patient characteristics and therapeutic outcomes of HPN therapy, such as number of hospital admissions, physiological complaints, and psychosocial interferences, was sent to 49 patients currently participating in a HPN program based at a university hospital. Questionnaires were returned by 42 patients. HPN-related complications were responsible for 39% of all reported hospital admissions during the previous year; of these, 27% were related to HPN catheters. Patients reported few physiological complaints, except for cramping in the hands and feet. Patients who complained of diarrhea had significantly more physiological complaints and psychosocial interferences than those who did not. The majority of patients had medical insurance coverage, but 26% had to pay at least part of the costs of HPN therapy. Only 25% of patients who were able to work did so. Most patients believed that HPN therapy had a very positive effect on their lives. The majority of patients in this HPN program appear to have a reasonable quality of life.

Pharmacy department costs and patient charges associated with a home parenteral nutrition program.

The pharmacy department costs of a home parenteral nutrition (HPN) program were identified, and the patient charges for HPN were compared with the charges for hospitalization for parenteral nutrition. Ten patients were randomly selected from 55 patients active in the HPN program at the University of Washington Hospital. Cost identification included quantification of supplies, personnel, equipment, freight, miscellaneous, and indirect costs. Patient charges were identified through billing documents. Charges included clinic visits and laboratory tests. Inpatient charges were identified in a similar manner and included a standard daily hospital charge. Average yearly costs to the pharmacy department were nearly +9000 per HPN patient. Patient charges for HPN were +48.19 per infusion day compared with +205.68 per infusion day for the hospitalized patient. The cost savings of HPN to the patient and the hospital were clearly demonstrated.

Clinical studies of a continuous extracorporeal cyanate treatment system for patients with sickle cell disease.

An extracorporeal carbamylation system was evaluated in two patients with sickle cell disease. Access was achieved with existing veins in one patient and an AV fistula in the second. Modifications in the treatment procedure were made as experience indicated. Levels of carbamylation of greater than 1 mol/mol of hemoglobin tetramer were achieved with 4 to 6 hr of treatment every 2 weeks. Cyanate returned to the patient averaged 68.5 mg per treatment. As expected, P50 values decreased and hemoglobin levels increased as the treatment progressed. Patterns of cyanate distribution among the red cell population were those predicted by computer calculations. These observations document the safety and reliability of the treatment system but do not permit conclusions as to efficacy.