Atrial thrombus and central venous dialysis catheters.

A native arteriovenous fistula is the first choice for hemodialysis access. Despite improved catheter designs and the use of internal jugular veins, thrombotic complications still occur when tunneled central venous catheters are used as an alternative. Although right atrial thrombus (RAT) is a well-characterized complication of long-term central venous cannulation, particularly when used for parenteral nutrition and chemotherapy in pediatric practice, only 9 reported cases previously have been associated with the long-term use of central venous catheters for hemodialysis. We report five cases of RAT seen at our unit between 1994 and 1998 in patients who had been dialyzed using tunneled catheters. In four of five cases, the diagnosis was made during the investigation of hemoptysis or dyspnea. In the fifth case, a screening transthoracic echocardiogram revealed the thrombus. Three of five of the patients suffered pulmonary emboli, and a fourth patient had an unexplained electromechanical dissociation cardiac arrest without definite evidence of pulmonary embolus. Our experience suggests that anticoagulated patients with RAT remain at risk of pulmonary embolism. One of our patients successfully underwent atrial thrombectomy. In four of five of our cases and four of nine cases in the literature, the central venous catheter tip was within the right atrium. Positioning of the central venous catheter tip low down in the superior vena cava or in the right atrium has been advocated to improve dialysis adequacy and to reduce the incidence of catheter thrombosis. However, placement of the catheter tip within the right atrium may be associated with an increased risk of RAT.

Home dialysis: lessons in patient education.

The concept of home haemodialysis for the regular treatment of renal failure was first put into practice in 1964, 30 years ago. It proved extremely successful. This paper describes the epidemiology of renal failure, the reasons for home haemodialysis and the educational role necessary to ensure its success. Continuous ambulatory peritoneal dialysis (CAPD), or autonomous dialysis, is a self-care peritoneal treatment which developed after 1978 for a wider age range of patients. Its rapid expansion needed a professional approach to patient education. Also discussed are the problems patients encounter with conceptual skills, as opposed to the easy acquirement of practical skills and the paper demonstrates how persons, without formal medical and nursing education, can master complex treatment skills.

Studies of aluminium mobilization in renal dialysis patients using the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one.

The oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1, deferiprone, CAS 30652-11-0) has been tested in 11 renal dialysis patients, 10 for aluminium and 1 for iron mobilization. L1 was administered just after the patients were placed on the haemodialyser and blood samples were collected before haemodialysis at 1 h and for some patients at longer intervals. Plasma aluminium levels before treatment ranged from 12 to 264 micrograms/l. A mean increase of 90% was observed within the first hour of oral administration in 6 patients who received a dose of L1 of 40-60 mg/kg. Plasma aluminium levels then progressively decreased after this period. Three patients with plasma aluminium of 30-66 micrograms/l who received a dose of L1 of less than 30 mg/kg had no significant changes in their plasma aluminium. In 2 other cases administration of L1 resulted in an over 30-fold increase of aluminium concentration in the dialysate of a continuous ambulatory peritoneal dialysis patient and of over 3 times the iron concentration in the dialysate of an iron loaded haemodialysis patient. In the last patient HPLC analysis of the dialysate samples obtained from the haemodialyser has shown complete clearance of L1 within 4 h but not of its glucuronide metabolite within 6.5 h of the L1 administration. No toxic side effects were observed in any of the 11 patients who received oral L1. These are the first clinical trials of an oral chelator in renal dialysis patients which suggest that oral L1 and possibly other alpha-ketohydroxypyridine chelators may have a use in the treatment of patients with aluminium overload.

Calcium set point progressively worsens in hemodialysis patients despite conventional oral 1-alpha hydroxycholecalciferol supplementation.

Calcium set point was measured in 12 patients on chronic hemodialysis. Dialysate calcium concentration was 1.65 mmol/l. Calcium carbonate (CaCO3) was used as the phosphate binder and oral 1-alpha hydroxycholecalciferol (alfacalcidol) was administered in a dose of 0.25-1.0 micrograms/day for 12 months. Comparing base line and post study values, there were no significant changes in ionized calcium (ICa++), intact immunoreactive parathyroid hormone (iPTH), plasma total calcium (TCa++), plasma phosphate (P), alkaline phosphatase (ALP), or aluminum (Al). However, the relative calcium set point significantly worsened (shifted to the right). Three patients developed hypercalcemia (25%) with a total calcium > 2.65 mmol/l. Total bone mineral content (BMC) fell suggesting demineralization. We conclude that this dose of oral alfacalcidol, CaCO3, and a dialysate calcium concentration of 1.65 mmol/l are not sufficient to halt the progression of secondary hyperparathyroidism in chronic hemodialysis patients. Measurement of calcium set point may be the best early measure of failure to prevent worsening of hyperparathyroidism.

Amyloidosis and other musculoskeletal complications of long-term regular haemodialysis.

Regular haemodialysis for at least five years is associated with musculoskeletal symptoms. Many of these are caused by a newly recognized disease, haemodialysis amyloidosis. Eighty-three patients who have dialysed for at least 10 years have been reviewed and their symptoms and treatment documented. As yet no cure for this crippling complication is available.

Musculoskeletal manifestations of amyloidosis. A review of 83 patients on haemodialysis for at least 10 years.

Long-term regular haemodialysis for chronic renal failure is associated with amyloidosis. In this condition excess amounts of the unexcretable plasma protein beta-microglobulin are laid down in tendons, joints and bones. Amyloidosis presents with various musculoskeletal disorders only after several years of dialysis. We reviewed 83 patients who had been dialysed for at least 10 years. The commonest complaint was severe joint pain in the absence of radiological changes of arthritis (41%), the shoulders usually being the most affected (33%). Carpal tunnel syndrome had developed in 26 patients, and was bilateral in 14 of them; at operation the presence of amyloid was confirmed. Six of these patients had recurrent symptoms after a further two to three years and required another decompression. Other manifestations of amyloidosis included trigger finger, flexor tendon contracture, spontaneous tendon rupture and pathological fracture through amyloid bone cysts. The frequency of symptoms was proportional to the duration of dialysis: all 13 patients on dialysis for over 20 years were affected. Symptoms developed earlier in older patients.

Apolipoprotein B turnover in dialysis patients: its relationship to pathogenesis of hyperlipidemia.

Exogenously labelled Iodine-125-VLDL (very low density lipoprotein) was given intravenously to twelve dialysis patients and four normal controls. Specific activities of I-125-VLDL apoB (apolipoprotein B) and I-125-IDLapoB (intermediate density lipoprotein apolipoprotein B) were measured for forty-eight hours. Synthesis rates (flux) and fractional catabolic rates (FCRs) of VLDLapoB and IDLapoB for hyperlipidemic (n = 8), normolipidemic (n = 4) dialysis patients and controls (n = 4) were calculated. Dialysis patients had lower VLDLapoB FCRs than controls (p less than 0.05); hyperlipidemic dialysis patients had marginally raised VLDLapoB flux over normolipidemics (p = 0.0508), suggesting apoB production might play a greater role in the pathogenesis of hyperlipidemia. Hyperlipidemics had lower IDLapoB FCRs than controls (p = 0.01). IDLapoB flux was similar in all three groups. The discrepancy in VLDLapoB fluxes between hyperlipidemics and normolipidemics with similar IDLapoB fluxes suggested that VLDLapoB could be directly catabolized in hyperlipidemics. ApoB concentration was increased in VLDL, IDL of hyperlipidemics when compared with normolipidemics (p less than 0.05) and controls (p = 0.01). Hyperlipidemic VLDL plasma levels were relatively enriched with cholesterol when compared with controls, p less than 0.01, and normolipidemics, p less than 0.05. These factors might all contribute towards accelerated atherogenesis in hyperlipidemic dialysis patients.

Efficacy and safety of teicoplanin in gram-positive peritonitis in patients on peritoneal dialysis.

Twelve cases of peritonitis caused by Gram-positive bacteria in 11 dialysis patients were treated with teicoplanin. Treatment, which was continued for three weeks, consisted of the addition of teicoplanin to the dialysis fluid. Six patients who were febrile on admission were also given a single intravenous dose of 400 mg teicoplanin. For patients on continuous ambulatory peritoneal dialysis 20 mg teicoplanin per litre was added to each dialysis bag during the first week of treatment, to alternate bags during the second week, and only to the overnight dwell bag in the third week. For patients on intermittent peritoneal dialysis, 20 mg/l teicoplanin was added at each dialysis session. Resolution of peritonitis occurred in all patients within one to five days (mean 2.2); nine were discharged within this period and the patients continued to treat themselves at home. The other two patients were kept in hospital for reasons unconnected with the peritonitis. Nine patients have remained well at follow-up 2-13 months (mean 6.3) later. Two patients, both of whom had Staphylococcus aureus peritonitis, relapsed three months after the end of treatment. Mean serum teicoplanin concentrations were less than 10 mg/l, except in one patient who was re-treated when he relapsed. No adverse effects were recorded; one patient who developed a conductive hearing loss was found to have otitis media and obstruction due to wax. We conclude that teicoplanin is safe and effective in treating peritonitis in patients on peritoneal dialysis.

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.

Hyperlipidemia in patients on maintenance hemo- and peritoneal dialysis: the relative pathogenetic roles of triglyceride production and triglyceride removal.

A study was undertaken in 76 patients on maintenance hemodialysis and 26 patients on maintenance peritoneal dialysis to elucidate the pathogenesis of hyperlipidemia in these patients. A high prevalence of hypertriglyceridemia and low concentrations of high density lipoprotein cholesterol was found. Hemodialysis patients had low or normal total cholesterol concentrations which were significantly lower than those on peritoneal dialysis. The length of treatment did not affect the prevalence of the lipid abnormalities. Both pre- and post-heparin fractional clearance rates of Intralipid were markedly reduced in both groups of dialysis patients and were correlated inversely with serum triglyceride concentrations. However, when compared with normal subjects with similar fractional clearance rates of Intralipid, both groups of dialysis patients had higher serum triglyceride concentrations, probably reflecting increased triglyceride production. Serum triglyceride concentrations in both groups of dialysis patients were positively correlated with plasma immunoreactive insulin levels. Furthermore, a significant inverse correlation was observed between plasma immunoreactive insulin levels and post-heparin fractional clearance rates of intralipid. It was concluded that insulin resistance probably caused the defective triglyceride removal, and that both decreased removal and increased production of triglycerides contributed to the hyperlipidemia in dialysis patients.

Hypophosphataemia after parathyroidectomy in chronic renal failure.

Out of 24 patients receiving haemodialysis who were subjected to parathyroidectomy, 13 developed hypophosphataemia; this persisted for 3-52 weeks (mean 10.6 weeks). Before operation these 13 patients had had significantly higher plasma alkaline phosphatase activities (p less than 0.01) and significantly higher values in iliac crest bone biopsy samples for active resorption surface and active formation surface (p less than 0.05 in each case) than the group who remained normophosphataemic. Significantly more of the patients who remained normophosphataemic had shown periarticular calcification in preoperative skeletal radiographs (p less than 0.001). Hypophosphataemia may result from reduced mobilisation of phosphate from bone or its increased accretion into bone, and resorption of phosphate from periarticular mineral deposits may protect against development.