Low-sodium haemodialysis without fluid removal improves blood pressure control in chronic haemodialysis patients

Hypertension is an important and well-established risk factor for both card iovascular and cerebrovascular disease. Hypertension is much more common in patients on renal replacement therapy than in the general population. Up t o 80% of patients on renal replacement therapy are hypertensive and about 5 0% of dialysis patients die from cardiovascular causes. Salt and water over load are major factors exacerbating hypertension in the dialysis population . This was a prospective crossover study of 10 patients examining the effec t of haemodialysis for 2 weeks using usual (Na+ 138-140 mmol/L) sodium dial ysate with a 2-week period of low (reduced by an average of 5 mmol/L Na+ to 133 mmol/L on average) sodium dialysate on inter-dialytic ambulatory blood pressure (ABPM) and trans-thoracic bioimpedance (TTB). Ten patients, mean age 67 years, completed the study (two women and eight men). No patient bec ame severely hyponatraemic during the study period. Mean 48 h inter-dialyti c blood pressure (BP) fell from 141/83 to 133/78 (P < 0.01). Mean arterial BP measured immediately prior to TTB fell from 92.8 mmHg to 87.5 mmHg (P < 0.01) during the low-sodium haemodialysis period. Afterload (systemic vascu lar resistive index - SVRI) measured by TTB fell significantly during the l ow-sodium haemodialysis period (SVRI on Na+-140 = 3426 cf. Na+-134 = 2281; P = 0.01). Dialysate sodium reduction without extra fluid removal had a ben eficial effect on inter-dialytic 48-h blood pressure in chronic stable haem odialysis patients. Lowering dialysate sodium reduced the systemic vascular resistance index as measured by TTB. Reduction of dialysate sodium was wel l tolerated, although mild dizzines and cramps did occur. These data sugges t that sodium overload and water overload may have independent effects on B P and that simple-to-achieve and modest changes in dialysate sodium could u sefully augment the action of antihypertensives in dialysis patients.