Role of dialysis sodium gradient on intradialytic hypertension: an observational study.
The causes of intradialytic hypertension (IDHyper) are not well understood and this condition can complicate the clinical management of hemodialysis (HD) patients.
To evaluate the potential role of intradialytic sodium gradient (NaG) on blood pressure values and IDHyper during HD.
206 prevalent HD patients on 3 times weekly HD treatment for at least 6 months (dialytic vintage 6-240 months) followed at our institution were studied. Mean age was 68 ± 14 years, 129 were men. For 2 consecutive months (24 HD sessions) after the start of observation, the following variables were evaluated in predialysis after the long interdialysis interval: pre-HD plasma sodium (pNa, mmol/l) and potassium (pK, mmol/l) concentrations (mean value of 8 determinations), pre- and post-HD systolic (SBP, mm Hg) and diastolic (DBP, mm Hg) blood pressure, dry body weight (dBW, kg), interdialytic weight gain (IDWG, kg), ultrafiltration rate (UFR, ml/kg/h), dialysis dose (Kt/V), protein catabolic rate (PCRn, g/kg/day), hemoglobin (Hb, g/dl). SBP, DBP, IDWG, UFR are the mean values of the 24 HD sessions. 76% of patients were on antihypertensive therapy, 171 patients were on bicarbonate HD, and 35 on HDF. Dialysate Na concentration was set at 140 mmol/l in all patients. Duration of HD and the blood and dialysate flow rate were kept constant during observation.
Data are expressed as mean ± SD; linear and multiple regression analysis and t test for unpaired data were employed. Significant differences were defined as p < 0.05.
Pre-HD pNa was 138.1 ± 2.3 mmol/l, pK 5.0 ± 0.4 mmol/l, dBW 67 ± 14 kg, IDWG 2.9 ± 0.8 kg, UFR 11.2 ± 3.7 ml/kg/h, Kt/V 1.43 ± 0.18, PCRn 1.13 ± 0.17 g/kg/day, and Hb 11.2 ± 0.8 g/dl. Pre- and post-HD SBP values were 139 ± 13 and 134 ± 12 mm Hg (p < 0.0001); pre- and post-HD DBP did not change significantly. A dialysis Na gradient (NaG) (dialysate Na - pre-HD pNa) was calculated, as well as the delta of SBP (ΔSBP) (post-HD SBP - pre-HD SBP). IDHyper was defined as ΔSBP >0. A significant direct correlation was found between NaG and ΔSBP (p < 0.0001) and multiple regression analysis with ΔSBP as dependent variable confirmed the strong correlation with NaG (p < 0.00001). According to ΔSBP behavior, 171 patients (83%) had a decrease or no change in post-HD SBP (group 1; no IDHyper); 35 patients (17%) increased their post-HD SBP (group 2; IDHyper). NaG values were significantly greater in patients in group 2 (group 1: 1.5 ± 2.2 vs. group 2: 3.3 ± 2.5, p < 0.0001).
This study shows that the intradialytic ΔSBP is independently and strongly associated with the dialytic NaG. The more positive the NaG (net intradialytic Na gain), the more positive the ΔSBP and IDHyper.
Movilli E
,Camerini C
,Gaggia P
,Zubani R
,Feller P
,Poiatti P
,Pola A
,Carli O
,Valzorio B
,Cancarini G
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Individualized reduction in dialysate sodium in conventional in-center hemodialysis.
Recent studies have focused on the association between dialysate sodium (Na(+)) prescriptions and interdialytic weight gain (IDWG). We report on a case series of 13 patients undergoing conventional, thrice-weekly in-center hemodialysis with an individualized dialysate Na(+) prescription. Individualized dialysate Na(+) was achieved in all patients through a stepwise weekly reduction of the standard dialysate Na(+) prescription (140 mEq/L) by 2-3 mEq/L until reaching a Na(+) gradient of -2 mEq/L (dialysate Na(+) minus average plasma Na(+) over the preceding 3 months). Interdialytic weight gain, with and without indexing to dry weight (IDWG%), blood pressure, and the proportion of treatments with cramps, intradialytic hypotension (drop in systolic blood pressure >30 mmHg) and intradialytic hypotension requiring an intervention were reviewed. At the beginning of the observation period, the pre-hemodialysis (HD) plasma Na(+) concentration ranged from 130 to 141 mEq/L. When switched from the standard to the individualized dialysate Na(+) concentration, IDWG% decreased from 3.4% ± 1.6% to 2.5% ± 1.0% (P = 0.003) with no change in pre- or post-HD systolic or diastolic blood pressures (all P > 0.05). We found no significant change in the proportion of treatments with cramps (6% vs. 13%), intradialytic hypotension (62% vs. 65%), or intradialytic hypotension requiring an intervention (29% vs. 33%). Individualized reduction of dialysate Na(+) reduces IDWG% without significantly increasing the frequency of cramps or hypotension.
Arramreddy R
,Sun SJ
,Munoz Mendoza J
,Chertow GM
,Schiller B
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