R.A. Baillod

Outcome in patients on continuous ambulatory peritoneal dialysis and haemodialysis: 4-year analysis of a prospective multicentre study

In a study in seven large renal units in England, the morbidity and mortality of all patients starting continuous ambulatory peritoneal dialysis (CAPD) and haemodialysis during 1983-85 were monitored prospectively over a 4-year period and related to reasons for choice of therapy and potential risk factors. 610 new patients (median age 52 years, range 3-80 years) started CAPD; 16% had diabetes mellitus and 21% cerebrovascular or cardiovascular disease. 329 patients (median age 48 years, range 5-77 years) started haemodialysis; 7% had diabetes mellitus and 17% cerebrovascular or cardiovascular disease. The Kaplan-Meier patient survival estimates at 4 years were 74% for haemodialysis and 62% for CAPD; technique survival figures for the same period were 91% for haemodialysis and 61% for CAPD. Coxs proportional hazards regression analysis showed that cerebrovascular/cardiovascular disease, age over 60 years, and diabetes mellitus were important predictors for survival in CAPD patients; there were no risk factors associated with permanent change to haemodialysis. In the haemodialysis group early change to CAPD was associated with presence of cerebrovascular or cardiovascular disease. The major cause of drop-out in both groups was transplantation. The mean length of hospital admission was 14.8 days per patient-year for CAPD and 12.4 days per patient-year for haemodialysis.

HYPOPHOSPHATAEMIC OSTEOMALACIA AFTER CADAVERIC RENAL TRANSPLANTATION

Abstract Seven patients with functioning renal transplants were found to have serum-inorganic-phosphate levels below normal, and five of them had X-ray evidence of osteomalacia Evidence for a phosphate leak came from abnormal high values for phosphate clearance and correspondingly low values for tubular reabsorption of phosphate. There was a slight metabolic acidosis. The cause of the phosphate leak is uncertain, but it could be that in these patients the proximal tubule is unduly sensitive to normal levels of parathyroid hormone.

Vitamin A toxicity and hypercalcaemia in chronic renal failure.

Serum vitamin A concentrations were measured in 38 patients undergoing haemodialysis, 24 of whom were taking multivitamin preparations containing vitamin A. Vitamin A concentrations were significantly higher in patients undergoing haemodialysis than in 28 normal controls (p less than 0.001). Patients taking vitamin A supplements had significantly higher vitamin A concentrations than those not taking them (p less than 0.05), and hypercalcaemic patients had higher concentrations than normocalcaemic patients (p less than 0.005). Withdrawal of vitamin A supplements in seven patients caused significant falls in serum vitamin A concentrations and plasma calcium concentrations (p less than 0.01 at two and three months in both cases) and in plasma alkaline phosphatase concentrations (p less than 0.01 at two months). Vitamin A toxicity can contribute to hypercalcaemia in patients undergoing haemodialysis, probably by an osteolytic effect. Multivitamin preparations containing vitamin A should therefore be prescribed with caution in these patients.

THREE YEARS' EXPERIENCE OF CONTINUOUS AMBULATORY PERITONEAL DIALYSIS

Patients on continuous ambulatory peritoneal dialysis (CAPD) were studied for three years. 29 of them who had been on CAPD for six months or more were compared with patients on intermittent peritoneal dialysis (IPD) and on haemodialysis (HD). CAPD patients had significantly higher levels of HDL-cholesterol than HD patients. Urea, potassium, phosphate, and urate levels were significantly lower, and haemoglobin levels significantly higher, than in the IPD and HD groups. 43 CAPD patients studied had a peritonitis rate of 2.22 episodes per patient-year. CAPD offers an alternative form of dialysis to those unsuitable for HD, but until peritonitis rates can be reduced CAPD cannot rival HD as a long-term treatment.

PERSISTENT HYPOPHOSPHATÆMIA AND OSTEOMALACIA IN DIALYSIS PATIENTS NOT ON ORAL PHOSPHATE-BINDERS: RESPONSE TO DIHYDROTACHYSTEROL THERAPY

Four patients who had been on regular haemodialysis for periods of 3 1/2 to 7 years became hypophosphataemic with plasma-phosphate concentrations of 2.5 mg/dl or less before dialysis. None of them had been taking oral phosphate-binders for 2 years or more. Histologically all the patients had an excess of osteoid on bone biopsy. Intestinal absorption of phosphate and calcium was impaired, despite normal or high serum-25-hydroxycholecaliferol concentrations. Treatment with oral dihydrotachysterol resulted in corrections of the phosphate malabsorption and increases in plasma-phosphate concentration. The initial low plasma-phosphate values in these patients before dialysis probably reflected a state of phosphate depletion caused by the combination of malabsorption, loss during dialysis, and a low dietary intake.

Survival Rates of Patients Treated by Home and Hospital Dialysis and Cadaveric Renal Transplantation

Of 109 patients admitted to the renal failure programme of the Royal Free Hospital 80·7% were surviving after six years. For patients on home dialysis the four-year rate was 86·2%, more deaths occurring in women than in men. The short-term survival rate of all patients was high—namely, 96·3% at six months and 94·4% at 12 months. Hence large increases in the rate of acceptance of patients as well as successful transplantation are necessary to balance acceptance and loss from this programme.

Plasma lecithin-cholesterol acyltransferase activities in uraemic patients

Plasma lecithin-cholesterol acyltransferase (LCAT) activity was measured in 43 haemodialysis and 15 peritoneal dialysis (CAPD) patients. LCAT activities in both groups of patients were significantly lower than those of normal subjects and did not correlate with any of the other biochemical parameters studied. The effect of intravenous administration of 100 U/kg of heparin on LCAT activity was examined in 21 haemodialysis patients and 19 normal subjects. Heparin inhibited LCAT activity by increasing plasma free fatty acid concentrations. LCAT remained inhibited throughout a dialysis session and returned towards pre-dialysis levels an hour after haemodialysis was discontinued. The cause of the low LCAT activities in the patients was not certain, but did not appear to be due to the presence of inhibitors in the uraemic plasma. The significance of these findings is discussed.

Fat clearance before and after heparin in chronic renal failure—Haemodialysis reduces post-heparin fractional clearance rates of intralipid

The effect of heparin on the kinetics of fat removal was studied in 15 subjects and it became apparent that the fat tolerance test could be performed after the administration of heparin. Therefore, fractional clearance rates of Intralipid were determined before and after heparin in three groups of patients: 18 in chronic renal failure, 11 on peritoneal dialysis and 17 on haemodialysis. Patients on peritoneal dialysis and on haemodialysis had similar serum triglyceride concentrations and comparable fractional clearance rates of Intralipid before heparin was given. However, the latter had significantly smaller increases in fractional rates of Intralipid clearance after the administration of heparin. Either gradual diminution of releasable releasable enzymes by regular heparinisation or activator concentrations becoming rate-limiting could be responsible for the low post-heparin fractional clearance rates observed in haemodialysis patients.

Effects of Age, Sex, and Polycystic Disease on Progressive Bone Disease of Renal Failure

A study of 150 patients undergoing haemodialysis has shown that age had a striking effect on the radiological presentation of renal bone disease, erosions being common in the young and uncommon in older patients and vascular calcification showing opposite trends to this. Men aged 20 to 59 years had a greater tendency to develop erosions than did women in this age range. Examination of a group of 53 patients over a period of five years showed that the half time for the development of vascular calcification was 4·6 years, erosions 26·7 years, and fractures 6·9 years. Nine out of 16 polycystic patients matched for age and sex with 50 controls did not develop erosions and had consistently less vascular calcification than the controls when examined over a six-year period.

Cefuroxime Pharmacokinetics in Continuous and Intermittent Peritoneal Dialysis

Pharmacokinetics of cefuroxime was studied in patients on continuous ambulatory or intermittent peritoneal dialysis. A single intravenous bolus (15 mg/kg) of cefuroxime provided a mean serum concentration of 86 mg/litre 5 min, 40 mg/litre 1 h, 163 mg/litre 24 h after the injection. The peritoneal clearance of cefuroxime varied widely among different individuals, ranging from 1.45 to 6.17 ml/min with a mean of 3.59 ml/min during 4-hour exchanges, and from 0,52 to 11.3 ml/min during 2-hour exchanges. A single injection (15 mg/kg) of the antibiotic could not provide satisfactory antibiotic concentrations in peritoneal effluent during peritoneal lavage. When cefuroxime had been added to peritoneal dialysis solution before the solution was instilled into the peritoneal cavity, a significant decrease in cefuroxime concentration occurred in the peritoneal effluent even after a short equilibration time. Furthermore, cefuroxime concentrations measured in residual dialysis solutions in the plastic bags ranged from 44.3 to 1,351% of the concentration of cefuroxime calculated from the added doses, indicating that despite great care, mixing of the antibiotic with dialysis solutions in plastic bags was far from uniform.