The effects of low-sodium peritoneal dialysis fluids on blood pressure, thirst and volume status.
BACKGROUND
Poor ultrafiltration is associated with worse outcomes in peritoneal dialysis (PD) patients. This might in part reflect problems associated with salt and water excess. Increasing the diffusive component of peritoneal sodium removal using low-sodium PD fluids might have beneficial effects on blood pressure (BP), thirst and fluid status that could translate into clinical benefits.


METHODS
Using a multicentre, prospective, baseline controlled (1 month), non-randomized intervention (2 months) design, two novel solutions designed from predictions using the three-pore model were investigated. In group A ([Na+] = 115 mmol/l), the glucose (G) was increased to 2.0% to compensate for reduced osmolality whereas in group B ([Na+] = 102 mmol/l), it was unchanged (2.5%). Both solutions were substituted for one 3- to 5-h exchange per day and no change was made to the rest of the dialysis regime.


RESULTS
Ten patients in group A and 15 in group B completed the study. Both solutions resulted in significant increases (30-50 mmol/dwell) in diffusive sodium removal during the test exchanges, P < 0.001. Ultrafiltration was maintained in group A but reduced in group B. Ambulatory nocturnal mean BP fell in group A [93.1 +/- 10.6 mmHg (+/-SD) versus 85.1 +/- 10.2 mmHg, P < 0.05], but was stable in group B (95.4 +/- 9.4 versus 95.1.1 +/- 10.7 mmHg, NS). Thirst reduced independent of appetite and mood in both groups by 2 months, more markedly in group A. Indices of fluid status, including TBW by bioimpedance and D dilution also improved in group A, P < 0.05, whereas weight increased in group B.


CONCLUSIONS
Increasing the diffusive component of sodium removal whilst maintaining ultrafiltration is associated with improvements in BP, thirst and fluid status. The lack of effect seen with uncompensated low-sodium dialysate suggests that these benefits cannot be achieved by manipulation of dialysate sodium removal alone. These observations provide valuable information of the design of future randomized studies to establish the clinical role for low-sodium dialysis fluids.
Davies
Simon
S
Department of Nephrology, University Hospital of North Staffordshire, Princes Road, Hartshill, Stoke-on-Trent, ST4 7LN, UK. SimonDavies1@compuserve.com
Carlsson
Ola
O
Simonsen
Ole
O
Johansson
Ann-Cathrine
AC
Venturoli
Daniele
D
Ledebo
Ingrid
I
Wieslander
Anders
A
Chan
Cian
C
Rippe
Bengt
B
D000328:Adult; D000339:Affect / Q000187:drug effects; D000368:Aged; D000369:Aged, 80 and over; D001066:Appetite / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D001823:Body Composition / Q000187:drug effects; D001834:Body Water / Q000187:drug effects*; D002097:C-Reactive Protein / Q000378:metabolism; D015314:Dialysis Solutions / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000379:methods*; D011446:Prospective Studies; D012709:Serum Albumin / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013894:Thirst / Q000187:drug effects*
D015314:Dialysis Solutions; D012709:Serum Albumin; D002097:C-Reactive Protein; D012964:Sodium