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Aim: Elevating serum ionized calcium levels is known to stabilize blood pressure during and after a hemodialysis session. The data on lowering calcium levels is limited., Subjects and Methods: This study examined the responses to an acute drop in ionized calcium during a four hour hemodialysis session in two subjects who differed in the presence (patient 1) or absence (patient 2) of anti-hypertensive medication and average weight loss of 4 kg (patient 1) or 2 kgs (patient 2) with each dialysis. Parathyroid hormone (PTH) levels were normal (patient 1) or very high (patient 2). A calcium free dialysate was used and the calcium infusion rate distal to the dialyzer was varied to produce either no change in ionized calcium for 10 dialyses, or a fall of at least 0.2 mmol/l for 10 dialyses. The sequence was randomized and was blinded to the observers and patients., Results: The fall in ionized calcium was similar in each individual, 0.37 +/- 0.11 and 0.34 +/- 0.05 mmol/l. PTH rose from 8.6 +/- 1.6 to 24.2 +/- 6.6 pmol/l for patient 1 and 144.6 +/- 59.9 to 234.8 +/- 32.3 pmol/l for patient 2: patient 1 showed a fall in blood pressure after dialysis associated with the fall in calcium. This was most pronounced in the upright position whereas there was no change for Patient 2. For Patient 1 standing mean blood pressure post-dialysis was 104 +/- 6 mmHg when the calcium was stable and 94 +/- 10 mmHg with hypocalcemia p <0.01. Mean blood pressure during dialysis was also lower with hypocalcemia 100 +/- 7 versus 92 +/- 9 p <0.05. There were no significant changes in blood pressure for patient 2. Neither of the patients had any symptoms attributable to hypotension or hypocalcemia., Conclusion: It was concluded that modest falls in ionized calcium were associated with a drop in standing blood pressure only when combined with other factors predisposing to vascular instability. Even so these decreases were small enough to be asymptomatic.

In this prospective controlled study the purpose was to assess the long-term safety of calcium-free dialysate (O Ca) for hemodialysis and to determine the optimum calcium replacement. With this technique there is no calcium in the dialysate and calcium is infused into the drip chamber distal to the dialyzer. We compared the use of a standard bicarbonate dialysate with a calcium free dialysate in two groups of patients. One group (study 1) received 10 mmol/hour Ca replacement, the other (study 2) received 13.3 mmol/hour Ca during dialysis. Each O Ca period lasted six months. This experimental period was compared with the six months preceding and following in the same patient and as well, with a concurrent control group who received standard bicarbonate dialysis either with 1.5 mmol/l calcium in the dialysate in study 1 or 1.75 mmol/l in study 2. Each group had nine to eleven subjects. No adverse effects were seen in either of the studies. With 10 mmol/hour calcium replacement there was a small but not significant rise in the pre-dialysis intact parathyroid hormone level (PTH) whereas in all the other groups it remained the same or fell. There was significantly less rise in the post-dialysis calcium in the same group and this was associated with a small but not significant fall in both pre-dialysis total and ionized calcium. It was concluded that the O Ca technique can be used for long periods and that 13.3 mmol/hour is a satisfactory replacement using Discap 140 dialyzers or their equivalent.

Three patients on long term hemodialysis were found to be hypophosphatemic. They were treated using a calcium-free dialysate to which phosphate was added to give a final concentration of 1 or 2 mmol/l. All corrected their low phosphates. Hypocalcemia developed in two patients when the calcium infusion rate was 15 ml/hour of 10% CaCl2. It is recommended that this should be increased to 20 ml/hour. Under these circumstances, correction of hypophosphatemia is possible with the transfer of approximately 30-35 mmol phosphate over a four-hour dialysis.

To determine the optimal infusion rate for calcium, when using a dialyzate which was calcium free, six patients were treated sequentially, in random order, with six different dialyzates. Three were calcium free and they were infused with replacement calcium at either 10, 15 or 20 ml/hour using 10% CaCl2. The other three used standard bicarbonate dialyzate with either 1.25, 1.5 or 1.75 mmol/l calcium. Ionized calcium and intact parathyroid hormone (Nichols IRMA PTH) were measured at the start and end of each dialysis. Ionized calcium rose slightly with 15 ml/hour calcium infusion and PTH fell 137 +/- 111 pg/ml. These changes were similar to those of 1.5 mmol/l calcium in standard bicarbonate. More PTH suppression and higher end dialysis calcium resulted from 20 ml/hour infusion or 1.75 mmol/l dialyzate calcium. It was concluded that 15 ml/hour is a suitable calcium infusion rate under normal conditions when using calcium-free dialyzate.

Auto-immunity as assessed by rheumatoid factor, anti-DNA, antinuclear, smooth muscle and mitochondrial circulating antibodies was evaluated in 2 groups of 25 patients with end-stage renal disease (ESRD) being maintained either on hemodialysis or on continuous ambulatory peritoneal dialysis (CAPD). In the group of hemodialysis patients, 56% showed at least one serological abnormality on pre-dialysis samples: anti-DNA (8%), antinuclear (8%), smooth muscle (40%) and mitochondrial (4%) antibodies; on post-dialysis samples, 64% of the patients demonstrated abnormalities due to a rise in the incidence of anti-DNA antibodies from 8-24%. In the group of CAPD patients, 44% showed at least one serological abnormality: rheumatoid factor (4%), anti-DNA (16%), antinuclear (24%) and smooth muscle (4%) antibodies. These serological changes were generally scattered randomly within both groups. In the hemodialysis group, 2 abnormalities were present in 1 patient pre-dialysis and in 3 post-dialysis. One CAPD patient had 2 abnormalities. No correlation of these findings with age, sex, duration of dialysis and nature of renal disease could be found. The results are discussed in the context of possible abnormal antigenic stimulation in ESRD patients maintained on either form of dialysis.

Studies were performed in patients on maintenance hemodialysis to evaluate the role of prolonged dialyzer reuse in the management of end-stage renal disease. For this purpose the patients were dialyzed without interruption with the same hollow fiber dialyzers (GambroR 120M) reprocessed with the Lixivitron IIR equipment. The data obtained from in vivo clearances in sixteen patients demonstrate that membrane permeability to small solutes (urea, creatinine, phosphate) is maintained up to thirty dialyzer uses. In vitro studies confirmed this observation and established that clearances of larger solutes (vitamin B12) are also maintained over similar extensive dialyzer reuse. Hematological and blood gas studies were performed serially during dialysis in five additional patients. Although circulating leucocyte and neutrophil counts, hemoglobin concentration as well as arterial pH and partial pressures of oxygen and carbon dioxide changed appropriately during dialysis, there was no observable difference from the first to the twentieth use of the same dialyzer. Thus, these results clearly demonstrate that prolonged dialyzer reuse in end-stage renal disease patients constitutes a stable form of renal replacement therapy provided adequate dialyzer reprocessing is applied.

A calcium-free, bicarbonate-containing concentrate was prepared for hemodialysis, which, after dilution, gave analyzed concentrations of sodium of 146 mmol/l, Cl 110 mmol/l, HCO3 of 35 mmol/l and pH of 8.3. When compared with standard bicarbonate dialysis, no important differences in blood chemistries, symptoms or signs were seen. The solution has been trouble-free in over 300 dialyses. Total amount of calcium lost uncorrected for time, dialyzer or blood flow was 40.6 +/- 1.1 mmol, n = 62. This loss was replaced by a calcium infusion into the venous line giving 40 mmol calcium over 4 h. The dialyzate calcium loss could be accurately predicted by sampling without collecting the total dialyzate volume. The uses of this concentrate for bicarbonate dialysis, citrate anticoagulation and avoidance of hypercalcemia in patients treated with oral calcium for phosphate binding is discussed.

As part of a study to evaluate the safety and efficacy of dialyzer reuse, a comparative study of two methods of dialyzer reprocessing, manual and automated, was conducted. Five stable end-stage renal disease patients on center hemodialysis were evaluated as to hematological and metabolic parameters throughout two series of three consecutive dialyses using first new and then reused dialyzers reprocessed according to each of the two methods. New dialyzers and reused dialyzers following automated reprocessing always induced a profound fall in circulating neutrophil counts shortly after the start of dialysis. Hemodialysis neutropenia was not observed, however, with reused dialyzers reprocessed manually unless the concentration of sodium hypochlorite (bleach) employed was made equal to that required in automated reprocessing by being raised from 1.0 to 4.3%. It would be reasonable to conclude from these results that among the various differences between the two dialyzer reprocessing methods, restoration of the original level of biocompatibility of the reused dialyzer's membrane is related to the concentration of the cleansing agent.

A case of hypophosphatemia-induced hypercalcemia during post-traumatic acute renal failure is described. Proposed causes for the hypophosphatemia include changes in tissue distribution of phosphate associated with hyperalimentation and phosphate losses during hemodialysis. In the absence of hyperparathyroidism the hypercalcemia as well as changes in osteoclast morphology found on bone biopsy are ascribed to a direct effect of hypophosphatemia on bone.

Dialysis patients are at risk for toxicity from formaldehyde used in the reprocessing of dialyzers for reuse; therefore, replacing formaldehyde as a dialyzer sterilant would be advantageous. The potential for RenNew-D as a sterilizing agent was investigated in seven stable in-center hemodialysis patients over 20 consecutive dialyses with cuprammonium cellulose hollow-fiber dialyzers. Treatment with RenNew-D showed no toxicity to patients or dialyzers except for two blood leaks occurring in one patient. The mean number of dialyzer uses was 4.9. In all the dialyzers that passed functional testing small solute clearances were maintained with reuse. The ability of RenNew-D to improve the biocompatibility of reused dialyzers was documented with mean neutrophil counts falling to only 78% of initial values during first reuse of dialyzers processed with RenNew-D compared with a decrease in neutrophil count to 2% of initial values during first use of the same dialyzers. Our results suggest that RenNew-D may be a useful alternative to formaldehyde for the purpose of dialyzer reuse. A reuse procedure that includes processing with RenNew-D is associated with improved biocompatibility, possibly because of maintenance of the blood-derived membrane coating established during prior dialysis.

A dialysis unit's introduction of automated recycling of dialysers is described. The responses of the staff and the patients are outlined, along with the pertinent ethical issues. Suggestions regarding the educational processes necessary with any innovation in long-term medical care are discussed.

Chronic dialysis patients at risk for aluminum osteomalacia in areas of low water-aluminum content are not well identified. We, therefore, studied retrospectively a cohort of 59 patients who underwent bone biopsy at two hospital-based dialysis centers in Montreal (water aluminum content less than 10 micrograms/L). Overall, 25% of patients biopsied had aluminum-related osteomalacia defined by aluminum staining of more than 30% of the trabecular surface and low levels of bone formation as measured by tetracycline labeling. Multiple linear regression analysis showed high predialysis serum creatinine (P less than .05) and the amount of aluminum prescribed per month (P less than .05) as the most important determinants of aluminum staining. We conclude that aluminum-related osteomalacia can be a frequent disease entity in areas of low water-aluminum content. Our findings also suggest predialysis serum creatinine and the amount of aluminum prescribed per month are risk factors for the development of aluminum-related osteomalacia. Though the relationship between serum creatinine and aluminum staining of trabecular bone is unclear, serum creatinine is probably a marker for adequacy of dialysis in these patients.

It is argued that consent by the patient to reuse dialyzers which have been mechanically cleansed is not required provided adequate standards of practice and safety are utilized. Based on medical benefits, administrative order and cost saving we propose that specific informed consent for such reuse should not be mandatory and that it could at times be unhelpful, both to care givers and recipients.

Forty-one PTFE grafts were studied prospectively with measurement of intragraft pressure and flow. As well, cardiac function was assessed by measuring cardiac output, ejection times and ejection fraction. It was shown that graft failure was associated with changes in graft pressures and flow. No untoward effects of graft flows of 1-2L/min were found on cardiac function.

Forty-one patients on our chronic hemodialysis program were assessed for the degree of progression of bone disease over an average period of 46 months. Seven patients were using a fluoridated dialysate. Four of these seven patients developed a marked increase in osteoid as judged by bone biopsy, while in the nonfluoridated group the amount of osteoid remained within normal limits.In the absence of fluoride, although osteitis fibrosa occurred, it was reversible in 10 out of 12 cases by dihydrotachysterol treatment, and overall there was no evidence of progression of bone disease at the end of the study period.

18 months clinical experience with 6 mm polytetrafluorethylene forearm grafts for hemodialysis access has been described. 35 grafts were implanted, all in patients who had unsuitable vessels for construction of a regular Brescia-Cimino forearm fistula. The overall patency was 71% with mean duration of 10.3 months, and at any one time more than 85% of the grafts at risk were functional. Complications, including undesirable flow rates, edema, thrombosis, aneurysm and cardiac failure have been discussed and rational methods of avoidance described. We believe the polytetrafluorethylene (PTFE) graft represents an important advance in hemodialysis access.

Expanded polytetrafluoroethylene (PTFE) is a new material now being used to create subcutaneous arteriovenous anastomoses for vascular access in hemodialysis. The authors have been impressed with the versatility of grafts made from this material and, where failure occurs, the ease with which surgical revision can be carried out. Two cases are described to illustrate the adaptability of this material to reconstruction. The authors' initial impression based on 22 months' experience is that PTFE grafts have appreciably modified the management with respect to vascular access, of many patients on long-term hemodialysis.

Should patients be treated when they have specifically refused treatment? Three competent patients are described with end-stage renal disease who, against the advice of their family, friends and care-givers, refused dialysis. Each was treated and subsequently they acknowledged their satisfaction with the outcome. Guidelines for treating patients when consent is refused are discussed and it is suggested that this is permissible in life-saving situations where the patients' refusal is idiosyncratic and irrational.

A method has been described for the measurement of blood flow in non branching grafts using the isotope dilution principle. The technique is simple, reproducible and consistent and can be performed in less than ten minutes.

Experience with chronic hemodialysis as a definitive form of therapy is described for six children aged 11 to 15 years at the onset. Duration on dialysis in the home has been between one and 4(1/2) years. All patients are alive and rehabilitated without serious complications. It is concluded that although transplantation is the most desirable form of treatment for children, long-term hemodialysis is an alternative acceptable second choice.

In 14 patients over the past three years, "bypass" cannulae have been inserted to relieve obstruction in cannulae used for chronic hemodialyses. Experience with these patients has prompted changes resulting in improved technique.Clotting was the major cause of cannulae failure and infection was the second most important cause. Other causes of failure included: venous atheroma, cannulae extrusion, aneurysms of the vessel at the cannulae tips, obstructive vegetation on the vessel wall, calcium deposits on the vessel wall, and thrombi on the vein walls.The mean survival time was improved from 1.9 months in 1963-1964 to over 9.0 months in 1965-1966. The longest surviving cannula set was two years and the shortest one week.It is considered that the most important factors contributing to increased cannula survival are improved cannula care by patients and staff, the use of angiography for accurate diagnosis, and prompt anticoagulation if atheromatous stenosis of the venous component is encountered.

Three cases of pericarditis with effusion associated with infection and occurring in patients under good biochemical control on hemodialysis are reported. Continuation of hemodialysis, even with regional heparinization, allowed further accumulation of fluid. Peritoneal dialysis was instituted, with subsequent improvement in all three patients. This treatment is recommended in the belief that it hastens the resolution of the condition and may obviate the necessity of establishing permanent or semi-permanent artificial pericardial drainage.