Does bicarbonate transfer have relevant hemodynamic consequences in standard hemodialysis?
BACKGROUND
In a previous study we demonstrated that mild metabolic alkalosis resulting from standard bicarbonate hemodialysis induces hypotension. This study aimed to compare hemodynamic consequences of either a decrease in the dialysate bicarbonate from 32 to 26 mmol/l or an increase in the dialysate calcium of 0.25 mmol/l and to verify whether the calcium shift secondary to alkalemia explains the consequences on blood pressure.


METHODS
In this randomized controlled trial with a single-blind, cross-over design, we used dialysis liquids with two different bicarbonate (32 mmol/l in modalities A and C, and 26 mmol/l in modality B) and calcium (1.25 mmol/l in modalities A and B, and 1.50 mmol/l in modality C) concentrations, and in 27 patients, 243 dialysis sessions, compared blood pressure, heart rate and the incidence of hypotension.


RESULTS
No significant differences were seen between A and B while an increase in systolic and diastolic blood pressures and a decrease in the incidence of hypotension (10.5 vs. 1.2%, p < 0.05) were documented in C. The subgroup of patients who with A showed a lower mean systolic blood pressure received more angiotensin-converting enzyme inhibitors or angiotensin II type-1 receptor blockers (36 vs. 0%, p<0.05) and in C showed a less important increase in systolic and diastolic pressures, but the incidence of hypotensive episodes between A and B was not significantly different (9.1 vs. 15.1%).


CONCLUSIONS
In the present study it was not possible to demonstrate hemo dynamic instability associated with mild metabolic alkalosis. Even in the subgroup showing a lower blood pressure with a higher dialysate bicarbonate, significant hemodynamic or clinical consequences were not noticed. The calcium shift (0.05 mmol/l) related to alkalemia would justify a mean decrease in systolic blood pressure of only about 1 mm Hg.
Gabutti
Luca
L
Department of Nephrology, Ospedale la Carità, Locarno, Switzerland. luca.gabutti@eoc.ch
Ross
Vanessa
V
Duchini
Francesca
F
Mombelli
Giorgio
G
Marone
Claudio
C
D000368:Aged; D000369:Aged, 80 and over; D000471:Alkalosis / Q000139:chemically induced; D001639:Bicarbonates / Q000494:pharmacology*; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology; D005260:Female; D006339:Heart Rate; D015312:Hemodialysis Solutions / Q000737:chemistry / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007022:Hypotension / Q000139:chemically induced; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000379:methods*
D001639:Bicarbonates; D015312:Hemodialysis Solutions; D002118:Calcium