Effects of Oral Sodium Bicarbonate Supplementation in Haemodialysis Patients (BicHD)

A Feasibility Randomised Controlled Trial: Effects of Oral Sodium Bicarbonate Supplementation in Patients on Haemodialysis

The purpose of the study is to investigate whether oral sodium bicarbonate supplementation to ensure a constant bicarbonate profile in haemodialysis patients will primarily lower predialysis potassium levels and secondary lead to improvements in cardiac function, muscle mass and dialysis related symptoms.

Background:

One of the functions of dialysis is to correct electrolyte abnormalities which occur with renal failure, such as variations in potassium and bicarbonate levels, which are linked to important clinical outcomes for patients. Metabolic acidosis, reflected by falling bicarbonate levels, is a frequent event in haemodialysis patients and its correction is one of the goals of effective dialysis. Bicarbonate replacement is routinely delivered during each dialysis session thrice weekly with the use of high dialysate bicarbonate. However, local and national data show that over 50% of patients fail to meet a bicarbonate level within the normal range before each dialysis session. Low predialysis bicarbonate levels of less than 22mmols/L have been linked with increased all-cause mortality in haemodialysis patients.

Evidence from previous studies suggests that a continuous replacement (i.e. daily) with oral sodium bicarbonate capsules may be a superior correction of acidosis to the current treatment of intermittent replacement during dialysis.

Aims and objectives:

This randomised controlled study aims to investigate the effects of oral sodium bicarbonate supplementation on:

Primary objective: Pre and post dialysis potassium without increasing intradialytic potassium gradient.

Secondary objectives:

1. Risk of arrhythmia as measured by ECG analysis
2. Muscle mass as measured by body composition monitoring
3. Muscle function as measured by handgrip strength
4. Haemodialysis related cramps as measured by a symptom scale-renal questionnaire

Patients will be recruited from Imperial College Healthcare NHS (National Heath Service) Trust haemodialysis units and randomised to two equally numbered groups. One group will receive the standard dialysis treatment (control) and the other one will receive the standard dialysis with the addition of capsules of sodium bicarbonate (intervention). The dose of sodium bicarbonate will be adjusted according to individual levels. The study duration is 16 weeks.

Inclusion Criteria:

Patients on haemodialysis for at least 3 months, Patients who primarily have predialysis bicarbonate levels of less than 22mmols/L over the last 6 months, Patients who are not already taking oral sodium bicarbonate, Able and willing to provide written informed consent

Exclusion Criteria:

Patients who primarily have predialysis potassium levels of less than 4mmols/L over the last 6 months, Patients who are already taking oral sodium bicarbonate, Patients on lithium, Bedbound patients, Pregnant patients, Dementia, Recurrent hospital admissions, Non-English speaking and unable to provide written informed consent