Hemodynamic behavior during hemodialysis: effects of dialysate concentrations of bicarbonate and potassium.

BACKGROUND/AIMS: Ultrafiltration that occurs during hemodialysis (HD) promotes profound alterations in a relatively short period of time. The dialysate content of bicarbonate (DBic) and potassium (DK) may have impact over intradialytic hemodynamics, which goes beyond ultrafiltration, and its impact was evaluated in a prospective cohort. METHODS: 30 patients under HD were submitted to hemodynamic assessment (HA) at the beginning and at the end of HD sessions, through a non-invasive method. Serum minus dialysate potassium concentration was expressed as K-Gap. Cardiac index (CI) and peripheral arterial resistance (PAR) variation (post-HD minus pre-HD) were expressed as ΔCI and ΔPAR. Dialysate content of sodium and calcium were expressed as DNa and DCa, respectively. RESULTS: Mean DNa, DK and DBic were, respectively, 136.4 ± 1.1, 2.1 ± 0.6 and 38.2 ± 2.1 mEq/L. In 15 patients, DCa was >1.5 mmol/L and in the other 15 patients ≤ 1.5 mmol/L. The K-Gap ranged from 1.4 to 5.1 mEq/l (median 3.0 mEq/L). There was a reduction in post-HD CI and systolic blood pressure (ΔCI = -0.72l/min/m(2) and -11.3±15.1mmHg, respectively, p<0.001 for both). Conversely, PAR increased (ΔPAR = 272dyn.s/cm(5), p<0.001). Lower post-HD CI was was associated to higher DBic (p=0.0013) and lower K-Gap (p=0.026). In multivariate analysis, ΔCI was dependent on DBic and K-Gap, whereas ΔPAR was dependent on dialysate calcium during HD. CONCLUSION: We confirmed that Na and Ca dialysate content exerts and important role on hemodynamic during HD. In addition, our findings pointed out that higher dialysate concentrations of bicarbonate and potassium promote lower cardiac performance at the end of hemodialysis session.

Removal of middle molecules with medium cutoff dialyzer in patients on short frequent hemodialysis.

INTRODUCTION: Medium cutoff (MCO) membranes for hemodialysis (HD) remove more effectively large middle molecules than high-flux (HF) membranes. In patients on in-center short frequent HD regimen (5 sessions per week, 2 hours and 30 minutes per session) the effect of MCO on middle weight uremic toxins has not been elucidated. METHODS: This retrospective study included 15 patients previously performing short frequent HD with HF dialyzer (HF-HD), that were switched to short frequent HD with MCO dialyzer (MCO-HD) for 2 months, and returned to HF-HD. The primary endpoint was the predialysis concentration of α1-acid glycoprotein during the different study phases. Secondary endpoints were predialysis concentration of other middle molecules, albumin, and assessment of the quality of life using the 36-item short-form health survey (SF-36). FINDINGS: During MCO-HD phase there was a reduction in mean ± SD α1-acid glycoprotein concentration (98.71 ± 25.2 vs. 88.6 ± 24.6 mg/dL, P = 0.107), followed by an increment 2 months after returning to HF-HD (89.18 ± 26.12 vs. 97.33 ± 31.29 mg/dL, P = 0.002); however, only the second variation was statistically significant. MCO-HD provided lower median predialysis concentration of prolactin (16 [10.2-25.6] vs. 14.1 [11.7-34.8] ng/mL, P = 0.036). Single-pool Kt/V, standard Kt/V, predialysis ß2-microglobulin, myoglobin, and SF-36 questionnaire remained stable during the first two phases (pre-MCO and MCO). ß2-Microglobulin increased in the post-MCO phase (20.02 ± 8.14 vs. 21.27 ± 7.64 µg/mL, P = 0.000). Mean predialysis concentration of albumin reduced significantly from pre-MCO vs. MCO phases (39.9 ± 3.7 vs. 38.3 ± 3.3 g/L, P = 0.020) and rebounded significantly from MCO vs. post-MCO phases (38.7 ± 3.1 vs. 41.3 ± 3.0 g/L, P = 0.007). DISCUSSION: In this retrospective analysis, short frequent MCO-HD promotes a reduction in prolactin, a middle weight uremic toxin, and trends toward a reduction in α1-acid glycoprotein. No patients developed hypoalbuminemia. These findings are encouraging and deserve investigation in prospective studies.

Parathyroidectomized patients have impaired capacity of peripheral vascular constriction during hemodialysis.

Parathyroidectomy (PTx) seems to improve cardiovascular outcomes and reduce blood pressure levels. However, the effect of PTx on hemodynamic changes during hemodialysis (HD) is still overlooked. This was a prospective cohort design. Patients with end-stage renal disease on maintenance HD were included. Diabetes and nonsinusal rhythm were exclusion criteria. History of PTx was recorded. Finometer monitor was used to access parameters immediately pre- and post-HD sessions. Cardiac index (CI) variation (ΔCI) and peripheral arterial resistance variation (ΔPAR) were the variables of interest. Biochemical and echocardiographic data were also obtained. PTx patients (n = 11) were matched to non-PTx patients (n = 20). ΔPAR was lower in PTx group in comparison with non-PTx group (P = 0.039), which was independent of parathyroid hormone (PTH) levels. Multiple regression analysis showed that PTx, ΔCI, and dialysate calcium remained independently associated with PAR variation and even adjusted for ultrafiltration rate (adjusted r(2) = 0.64). In conclusion, parathyroidectomized patients have impaired capacity of vasoconstriction in response to ultrafiltration, an effect independent of serum PTH levels. Further studies are needed to elucidate mechanisms explaining the interaction between PTx and systemic vascular tonus.