Prevalence, recurrence and seasonal variation of hyperkalemia among patients on hemodialysis.

PURPOSE: Observational studies have shown that among patients on hemodialysis, hyperkalemia is strongly associated with excess risk for cardiovascular-related hospitalizations and sudden cardiac death. However, the actual burden of hyperkalemia, the rates of its recurrence and seasonality in its variation still remain unclear. METHODS: Between June 2020 and May 2021, 1786 mid-week pre-dialysis serum potassium (sK) measurements were retrospectively recorded from 149 patients receiving thrice-weekly hemodialysis in a single-center in Thessaloniki, Greece. The prevalence, recurrence and seasonal variation of hyperkalemia were assessed using three pre-specified sK thresholds (≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L). RESULTS: At baseline, 60.4%, 42.2% and 13.4% of patients had sK levels ≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L, respectively. At any time-point during follow-up, 85.2%, 69.8% and 38.9% of patients experienced at least one hyperkalemic event ≥ 5.1, ≥ 5.5 and ≥ 6.0 mmol/L, respectively. Of the 104 patients experiencing an initial sK elevation ≥ 5.5 mmol/L, hyperkalemia at the same threshold reoccurred in 60.6% at month 1, in 47.1% at month 2 and in 46.1% at month 3 of follow-up. Seasonal variation was also observed, with the prevalence of hyperkalemia to be significantly higher in summer. Shorter delivered hemodialysis < 4 h/session (OR: 2.568; 95% CI 1.045-6.313) and the use of a high dialysate K concentration (OR: 14.646; 95% CI 2.727-78.647) were the 2 factors that were independently associated with hyperkalemia. CONCLUSION: The present study shows that among hemodialysis patients, the rates of hyperkalemia prevalence and recurrence are very high, reflecting the large unmet need to identify more effective potassium-lowering therapeutic interventions in this high-risk population.

Prevalence and control of hypertension among patients on haemodialysis.

BACKGROUND: Earlier studies provided considerably variable estimates on the prevalence and control rates of hypertension in haemodialysis because of their heterogeneity in definitions and blood pressure (BP) measurement techniques applied to detect hypertension. MATERIALS AND METHODS: In this cross-sectional study, 116 clinically stable haemodialysis patients from 3 dialysis centres of Northern Greece underwent home BP monitoring for 1 week with the validated automatic device HEM-705 (Omron, Healthcare). Routine BP recordings taken before and after dialysis over 6 consecutive sessions were also prospectively collected and averaged. Hypertension was defined as: (a) 1-week averaged home BP ≥ 135/85 mm Hg; (b) 2-week averaged predialysis BP ≥ 140/90 mm Hg; and (c) 2-week averaged postdialysis BP ≥ 130/80 mm Hg. Participants on treatment with ≥1 antihypertensives were also classified as hypertensives. RESULTS: The prevalence of hypertension was 88.8% by home, 86.2% by predialysis and 91.4% by postdialysis BP recordings. In all, 96 participants (82.7%) were being treated with an average of 2.0 ± 1.1 antihypertensive medications. Among drug-treated participants, 32.6% were controlled by home, 50.5% by predialysis and 45.3% by postdialysis BP recordings. In multivariate logistic regression analysis, greater use of antihypertensive medications and postdialysis overhydration, assessed with bioimpedance spectroscopy, were both independently associated with higher odds of inadequate home BP control. CONCLUSIONS: This study shows that the prevalence, but mainly the control rates of hypertension in patients on haemodialysis, differs between peridialytic and interdialytic BP recordings. Therefore, the wider use of home BP monitoring may improve the determination of BP control status in this high-risk population.

Reversed connection of cuffed, tunneled, dual-lumen catheters with increased blood flow rate maintains the adequacy of delivered dialysis despite the higher access recirculation.

PURPOSE: Reversing the connection mode of permanent dual-lumen dialysis catheters results in higher access recirculation that may compromise the dialysis adequacy. The purpose of this study is to investigate the effect of reversed-connected dialysis with a higher versus a standard blood flow rate (Qb) on adequacy parameters and access recirculation. MATERIALS AND METHODS: In a cross-over design, 46 prevalent dialysis patients with a properly functioning cuffed, tunneled, dual-lumen catheter were evaluated in three consecutive mid-week dialysis sessions. At baseline, participants were evaluated under standardized conditions (correct connection, Qb = 300 ml/min). In Phase A, dialysis was performed with reversed connection and Qb = 300 ml/min. In Phase B, dialysis was performed with reversed connection and Qb = 400 ml/min. The sequence of evaluations (Phase A and B or vise verse) was randomized. All other dialysis-related parameters were unchanged in all three occasions. RESULTS: As expected, compared with baseline, reversed-connected dialysis in Phase A resulted in lower URR and spKt/V, and in a higher recirculation rate. Compared with baseline, reversed-connected dialysis with a higher Qb in Phase B resulted in an even higher recirculation rate, but the parameters of dialysis adequacy were not different. Increase in Qb from 300 to 400 ml/min resulted in an improvement of the dialysis adequacy (URR: 64.1 ± 7.8% vs. 70.6 ± 8.2%, P < 0.001; spKt/V: 1.22 ± 0.3 vs. 1.45 ± 0.3, P < 0.001) despite the higher recirculation rate. CONCLUSION: This study suggests that reversed-connected dialysis with increasing Qb maintains the adequacy of the delivered dialysis despite the compensatory increase in recirculation.

Ambulatory aortic blood pressure, wave reflections and pulse wave velocity are elevated during the third in comparison to the second interdialytic day of the long interval in chronic haemodialysis patients.

BACKGROUND: Increased arterial stiffness and aortic blood pressure (BP) are independent predictors of cardiovascular outcomes in end-stage renal disease. The 3-day interdialytic interval is associated with elevated risk of cardiovascular morbidity and mortality in haemodialysis. This study investigated differences in ambulatory aortic BP and arterial stiffness between the second and third day of the long interdialytic interval. METHODS: Ambulatory BP monitoring with Mobil-O-Graph monitor (IEM, Stolberg, Germany) was performed in 55 haemodialysis patients during a 3-day interval. Mobil-O-Graph records oscillometric brachial BP and pulse waves and calculates aortic BP and augmentation index (AIx) as measure of wave reflections, and pulse wave velocity (PWV) as measure of arterial stiffness. RESULTS: Ambulatory aortic systolic blood pressure (SBP) and diastolic blood pressure (DBP) were higher during the third versus second interdialytic day (123.6 ± 17.0 versus 118.5 ± 17.1 mmHg, P < 0.001; 81.5 ± 11.8 versus 78 ± 11.9 mmHg, P < 0.001, respectively). Similar differences were noted for brachial BP. Ambulatory AIx and PWV were also significantly increased during the third versus second day (30.5 ± 9.9 versus 28.8 ± 9.9%, P < 0.05; 9.6 ± 2.3 versus 9.4 ± 2.3 m/s, P < 0.001, respectively). Differences between Days 2 and 3 remained significant when day-time and night-time periods were compared separately. Aortic SBP and DBP, AIx and PWV showed gradual increases from the end of dialysis session onwards. Interdialytic weight gain was a strong determinant of the increase in the above parameters. CONCLUSIONS: This study showed significantly higher ambulatory aortic BP, AIx and PWV levels during the third compared with the second interdialytic day. These findings support a novel pathway for increased cardiovascular risk during the third interdialytic day in haemodialysis.

Ambulatory recording of wave reflections and arterial stiffness during intra- and interdialytic periods in patients treated with dialysis.

BACKGROUND AND OBJECTIVES: Wave reflections and arterial stiffness are independent cardiovascular risk factors in ESRD. Previous studies in this population included only static recordings before and after dialysis. This study investigated the variation of these indices during intra- and interdialytic intervals and examined demographic, clinical, and hemodynamic variables related to arterial function in patients undergoing hemodialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Between February 2013 and May 2014, a total of 153 patients receiving maintenance hemodialysis in five dialysis centers of northern Greece underwent ambulatory BP monitoring with the newly introduced Mobil-O-Graph device (IEM, Stolberg, Germany) over a midweek dialysis session and the subsequent interdialytic period. Mobil-O-Graph is an oscillometric device that records brachial BP and pulse waves and estimates, via generalized transfer function, aortic BP, augmentation index (AIx) as a measure of wave reflections, and pulse wave velocity (PWV) as an index of arterial stiffness. RESULTS: AIx was lower during dialysis than in the interdialytic period of dialysis-on day (Day 1) (mean±SD, 24.7%±9.7% versus 26.8%±9.4%; P<0.001). In contrast, PWV remained unchanged between these intervals (9.31±2.2 versus 9.29±2.3 m/sec; P=0.60). Both AIx and PWV increased during dialysis-off day (Day 2) versus the out-of-dialysis period of Day 1 (28.8%±9.8% versus 26.8%±9.4% [P<0.001] and 9.39±2.3 versus 9.29±2.3 m/sec [P<0.001]). Older age (odds ratio [OR], 1.09; 95% confidence interval [95% CI], 1.02 to 1.15), female sex (OR, 7.56; 95% CI, 1.64 to 34.81), diabetic status (OR, 8.84; 95% CI, 1.76 to 17.48), and higher mean BP (OR, 1.17; 95% CI, 1.09 to 1.27) were associated with higher odds of high AIx; higher heart rate was associated with lower odds (OR, 0.71; 95% CI, 0.63 to 0.80) of high AIx. Older age (OR, 2.04; 95% CI, 1.61 to 2.58) and higher mean BP (OR, 1.15; 95% CI, 1.05 to 1.27) were independent correlates of high PWV. CONCLUSIONS: This study showed a gradual interdialytic increase in AIx, whereas PWV was only slightly elevated during Day 2. Future studies are needed to elucidate the value of these ambulatory measures for cardiovascular risk prediction in ESRD.

A rare retroperitoneal schwannoma in a patient with neurofibromatosis Type 2.

Neurofibromatosis Type 2 (NF2) is a dominantly inherited tumour-prone disorder, characterized by the development of multiple schwannomas, meningiomas and ependymomas. Its prevalence is around 1:60 000. Vestibular schwannoma (VS) is the hallmark of NF2. Retroperitoneal schwannomas are expected to occur in only 3% of cases. We present the case of a large retroperitoneal schwannoma in a patient with NF2. A well-circumscribed heterogenic mass (9.5 × 4 × 4 cm) behind and under the left kidney and extending into the left retroperitoneal space was revealed during a lumbar and retroperitoneal space magnetic resonance imaging (MRI). Brain, orbits, cervical, thoracic and lumbar MRI revealed bilateral VS, multiple meningiomas as well as multiple schwannomas and ependymomas in the cervical, thoracic and lumbar spine. The retroperitoneal mass represents a schwannoma probably derived from an intercostal nerve. The patient underwent neurosurgical excision of the VS, and 3 months later, the patient's condition remained stable.

HCV-RNA qualitative assay based on transcription mediated amplification improves the detection of hepatitis C virus infection in patients on hemodialysis: results from five hemodialysis units in central Greece.

BACKGROUND: End-stage renal disease patients (ESRD) on maintenance hemodialysis (HD) are at increased risk of acquiring hepatitis C virus (HCV) infection. An early and accurate diagnosis of HCV infection is important for the prevention of viral transmission and the management of ESRD patients on HD but conventional ELISA and PCR have often failed to reveal active HCV infection. OBJECTIVES: This study evaluated the prevalence of HCV infection in ESRD patients from all HD units in central Greece using a sensitive HCV-RNA transcription mediated amplification (TMA) assay and compared its sensitivity with that of anti-HCV ELISA. STUDY DESIGN: Anti-HCV antibody (third generation ELISA), HCV-RNA (TMA) and HCV genotypes (HCV TMA-LiPA) were determined in 366 ESRD Greek patients. RESULTS: In total, 132 (36%) ESRD patients were HCV positive by ELISA or TMA; 44 by TMA alone, 16 by ELISA alone and 72 positive by both assays. More than half of the viraemic patients had genotype 3a. CONCLUSIONS: HCV-RNA (TMA) assay appears to increase the accuracy in the diagnosis of HCV infection in HD patients compared to the anti-HCV ELISA and could serve as an additional screening tool in these patients.

Unit dosing of darbepoetin alfa for thetreatment of anemia in patients with end-stage renal disease being switched from recombinant human erythropoietin: Results of a phase IIIb, 27-week, multicenter, open-label study in Greek patients.

BACKGROUND: Darbepoetin alfa is an erythropoietis-stimulating glycoprotein with a ∼3-fold longer t1/2 and greater biological activity compared with recombinant human erythropoietin (rHuEPO). OBJECTIVE: The objective of this study was to evaluate the efficacy andtolerability of long-term (24-week) darbepoetin alfa treatment in maintaining hemoglobin (Hb) concentrations in the target range of 10 to 13 g/dL in patients undergoing dialysis; the patients were switched from rHuEPO to a less-frequent dosing regimen of darbepoetin alfa without an increase in dose. METHODS: In this Phase IIlb, open-label, multicenter study, patients withend-stage renal disease (ESRD) undergoing dialysis who were receiving rHuEPO BIW or TIW at baseline were switched to darbepoetin alfa QW; patients receiving rHuEPO QW were switched to darbepoetin alfa Q2W Administration of darbepoetin alfa was by the same route as previous rHuEPO administration (IV or SC). Patients received darbepoetin alfa for 24 weeks, including a 20-week drug titration period followed by a 4-week, stable-dose evaluation period. The mode, dose, and frequency of administration of darbepoetin alfa were compared with those of baseline rHuEPO. Tolerability assessment was based on spontaneous reporting and laboratory tests (hematology, vital sign measurement, iron status, and biochemistry). RESULTS: The study comprised 173 patients who were divided into 2 groups by route of administration (IV group, n = 146; SC group, n = 27). Mean (SE) adjusted increases in Hb concentration from baseline to the evaluation period for patients receiving darbepoetin alfa QW were 0.94 (0.32) g/dL and 0.38 (0.30) g/dL for the IV or SC routes, respectively (P = 0.004 and NS, respectively). For patients receiving darbepoetin alfa Q2W the mean (SE) adjusted increases in Hb concentration were 0.08 (0.53) g/dL and 0.48 (0.35) g/dL for the IV and SC routes, respectively (both, P = NS). No significant differences in IV/SC dose ratio were observed between the 2 routes of administration. In addition, no increases in darbepoetin alfa dose were observed. The most commonly reported adverse events were hypertension (8 patients [5%]) and vascular access thrombosis (4 [2%]). The incidence of treatment-related adverse events was 6 (3%). CONCLUSIONS: Darbepoetin alfa effectively maintained Hb concentrations within the target range without an increase in dose, even at a reduced dosing frequency. Overall, darbepoetin alfa was well tolerated.