Effect of Low-Sodium versus Conventional Sodium Dialysate on Left Ventricular Mass in Home and Self-Care Satellite Facility Hemodialysis Patients: A Randomized Clinical Trial

BACKGROUND

Fluid overload in patients undergoing hemodialysis contributes to cardiovascular morbidity and mortality. There is a global trend to lower dialysate sodium with the goal of reducing fluid overload.

METHODS

To investigate whether lower dialysate sodium during hemodialysis reduces left ventricular mass, we conducted a randomized trial in which patients received either low-sodium dialysate (135 mM) or conventional dialysate (140 mM) for 12 months. We included participants who were aged >18 years old, had a predialysis serum sodium ≥135 mM, and were receiving hemodialysis at home or a self-care satellite facility. Exclusion criteria included hemodialysis frequency >3.5 times per week and use of sodium profiling or hemodiafiltration. The main outcome was left ventricular mass index by cardiac magnetic resonance imaging.

RESULTS

The 99 participants had a median age of 51 years old; 67 were men, 31 had diabetes mellitus, and 59 had left ventricular hypertrophy. Over 12 months of follow-up, relative to control, a dialysate sodium concentration of 135 mmol/L did not change the left ventricular mass index, despite significant reductions at 6 and 12 months in interdialytic weight gain, in extracellular fluid volume, and in plasma B-type natriuretic peptide concentration (ratio of intervention to control). The intervention increased intradialytic hypotension (odds ratio [OR], 7.5; 95% confidence interval [95% CI], 1.1 to 49.8 at 6 months and OR, 3.6; 95% CI, 0.5 to 28.8 at 12 months). Five participants in the intervention arm could not complete the trial because of hypotension. We found no effect on health-related quality of life measures, perceived thirst or xerostomia, or dietary sodium intake.

CONCLUSIONS

Dialysate sodium of 135 mmol/L did not reduce left ventricular mass relative to control, despite improving fluid status.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

The Australian New Zealand Clinical Trials Registry, ACTRN12611000975998.

Pharmacokinetics of metformin in patients with chronic kidney disease stage 4 and metformin-naïve type 2 diabetes

The pharmacokinetics of metformin therapy in patients with chronic kidney disease stage 4 (CKD-4) were studied using data from the largest Phase I consecutive cohort trial yet performed in this population. Eighteen metformin-naïve men and women with Type 2 Diabetes and creatinine clearance (CrCl) in the range 18-49 mL/min (eGFR 15-29 mL/min/1.73 m2) were allocated to daily immediate-release metformin of 250 mg, 500 mg, or 1000 mg. A first-dose profile and trough concentrations for 4 weeks were taken on all patients. Pharmacokinetic (PK) parameters were estimated by fitting a first-order compartment model with absorption in a peripheral compartment to concentrations measured 24 hours post-first dose. Single-dose PK parameters time to maximum concentration (tmax) and maximum concentration (Cmax) were consistent with previous observations in patients with normal renal function (healthy and diabetic), as was the association between CrCl and apparent total oral clearance (Cl/F). However, patients with a CrCl below 32 mL/min had trough concentrations that were consistently above the steady-state minimum implied by the population PK model. This suggests the model may not apply to patients with CrCl below 32 mL/min. Metformin in doses of 500-1000 mg/day could be taken by CKD-4 patients. However, the single-compartment model breaks down as CrCl declines below 32 mL/min suggesting that metformin levels should be monitored regularly in progressive stage 4 CKD.

Feasibility study of colestipol as an oral phosphate binder in hemodialysis patients

BACKGROUND

Currently available calcium- and aluminium-based phosphate binders are dose limited because of potential toxicity, and newer proprietary phosphate binders are expensive. We examined phosphate-binding effects of the bile acid sequestrant colestipol, a non-proprietary drug that is in the same class as sevelamer.

METHODS

The trial was an 8 week prospective feasibility study in stable hemodialysis patients using colestipol as the only phosphate binder, preceded and followed by a washout phase of all other phosphate binders. The primary study endpoint was weekly measurements of serum phosphate. Secondary endpoints were serum calcium, lipids and coagulation status. Analyses used random effects mixed models.

RESULTS

Thirty patients were screened for participation of which 26 met criteria for treatment. At a mean dose of 8.8 g/24 h of colestipol by study end, serum phosphate dropped from 2.24 to 1.96 mmol/L (P < 0.001). Three patients required calcium supplementation. LDL cholesterol dropped from 1.75 to 1.2 mmol/L (P < 0.001). Three patients dropped out because of side effects or intolerance of the required dose.

CONCLUSION

The results support the feasibility of a larger trial to determine the efficacy of colestipol as a phosphate binder and that other non-proprietary anion-exchange resins may also warrant investigation.

Exsanguination of a home hemodialysis patient as a result of misconnected blood-lines during the wash back procedure: a case report

Background

Home hemodialysis is common in New Zealand and associated with lower cost, improved survival and better patient experience. We present the case of a fully trained home hemodialysis patient who exsanguinated at home as a result of an incorrect wash back procedure.

Case presentation

The case involves a 67 year old male with a history of well controlled hypertension and impaired glucose tolerance. He commenced on peritoneal dialysis in 2006 following the development of end stage kidney failure secondary to focal segmental glomerulosclerosis. He transferred to hemodialysis due to peritoneal membrane failure in 2010, and successfully trained for home hemodialysis over a 20 week period. Following one month of uncomplicated dialysis at home, he was found deceased on his machine at home in the midst of dialysis. His death occurred during the wash back procedure performed using the “open circuit” method, and resulted from misconnection of the saline bag to the venous end of the extracorporeal blood circuit instead of the arterial end. This led to approximately 2.3L of his blood being pumped into the saline bag resulting in hypovolaemic shock and death from exsanguination.

Conclusions

Despite successful training, critical procedural errors can still be made by patients on home hemodialysis. In this case, the error involved misconnection of the saline bag for wash back. This case should prompt providers of home hemodialysis to review their training protocols and manuals. Manufacturers of dialysis machinery should be encouraged to design machines specifically for home hemodialysis, and consider distinguishing the arterial and venous ends of the extracorporeal blood circuit with colour coding or incompatible connectivity, to prevent occurrences such as these in the future.

The atom-cavity microscope: single atoms bound in orbit by single photons

The motion of individual cesium atoms trapped inside an optical resonator is revealed with the atom-cavity microscope (ACM). A single atom moving within the resonator generates large variations in the transmission of a weak probe laser, which are recorded in real time. An inversion algorithm then allows individual atom trajectories to be reconstructed from the record of cavity transmission and reveals single atoms bound in orbit by the mechanical forces associated with single photons. In these initial experiments, the ACM yields 2-micrometer spatial resolution in a 10-microsecond time interval. Over the duration of the observation, the sensitivity is near the standard quantum limit for sensing the motion of a cesium atom.

A simple method of tumour culture

We describe a simple explant primary cell culture system which maintains the normal tumour stroma relationship. This technique utilises conventional cell culture methods combined with the skills found in the histopathological laboratory. This produces sections of tumour visible by light microscopy. Using this method we were able to maintain for up to 7 days good morphological preservation and demonstrated continued proliferation. This technique produces histological sections of tumour following in vitro culture that can be utilised for other molecular studies, e.g. immunohistochemistry and in situ PCR. This method should prove invaluable to pathologists enabling direct visualisation and localisation of molecular events involved in tumour growth.

Immunocytochemical quantitation of inflammatory cells associated with Helicobacter pylori infection

Inflammatory cells in Helicobacter pylori-associated gastritis (HAG) were quantified. The results were compared with the gastric biopsy samples from patients with non-Helicobacter pylori gastritis (non-HAG). In order to detect immunocytochemically sensitive antigens, the biopsy samples were acetone-fixed at -20 degrees C and processed into glycol methacrylate at 4 degrees C. Parallel routine biopsy samples were formalin-fixed and paraffin-embedded. A larger, more selective retrospective study was also established examining routinely processed gastric biopsy samples. The results of both studies were expressed as numbers of individual cell types/mm2 of gastric mucosa, and showed that neutrophil granulocytes were significantly increased in HAG whereas T-lymphocytes were not. Heli. pylori colonisation was associated with a significant increase of CD8-positive lymphocytes in the epithelium of the crypts.