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Biomedical subjects

Andreas Pierratos

Publications and source records attributed to Andreas Pierratos.

At least 19 recordsLinked to original sources
PubMed2006

Sodium citrate 4% locking solution for central venous dialysis catheters--an effective, more cost-efficient alternative to heparin.

BACKGROUND: Thrombosis of the central venous haemodialysis catheter compromises dialysis adequacy and catheter survival. Heparin containing catheter-locking solution has been associated with bleeding, interferes with INR (prothrombin time/international normalized ratio) measurements and is costly. Sodium citrate has been used successfully as a catheter-locking solution, but long-term experience with its use as the exclusive locking solution has not been published. METHODS: Our haemodialysis unit converted to locking all central venous haemodialysis catheters with sodium citrate 4% instead of heparin 10 000 U/ml. A retrospective analysis compared the outcomes of the year prior and after the conversion. Flow-related catheter exchange rate, prevalence of INR assay interference, tissue plasminogen activator (rt-PA) utilization rate, rate of bacteraemias and annual cost of locking agent were examined. RESULTS: During the study period, 30 925 and 37 139 catheter days were identified during the heparin and citrate years, respectively. The rate of flow-related catheter exchange was not different during the two periods (1.81 vs 1.88 per 1000 catheter days, P = 0.89). Falsely elevated INR values were eliminated with citrate and the rate of rt-PA treatments was similar during the two periods (4.1 vs 3.23 per 1000 catheter days respectively, P = 0.07). The number of bacteraemias was similar during the two periods (0.77 vs 0.94 per 1000 catheter days respectively, P = 0.36) There was an 85% reduction in the costs associated with catheter-locking therapy during the citrate period. CONCLUSIONS: The pharmaco-economic benefits of sodium citrate 4% are well supported by this analysis. Furthermore, citrate offers several clinical advantages over concentrated heparin: citrate lock avoids heparin-associated bleeding complications, improves reliability of INR assays and provides an effective alternative for patients with suspected or confirmed heparin-induced thrombocytopenia.

Aged↗
PubMed2006

The natural history of coronary calcification progression in a cohort of nocturnal haemodialysis patients.

BACKGROUND: End-stage renal disease (ESRD) is associated with a markedly increased cardiac calcification burden, as reflected by computed tomography scans of the heart. Nocturnal haemodialysis (NHD) is a novel form of renal replacement therapy which has multiple physiologic effects that may affect vascular calcification, including improvements in phosphate and uraemia control. The objective of the present study is the determination of the natural history of coronary calcification progression in patients converted to NHD, and the examination of the relationships between calcification risk factors and calcification progression in these patients. METHODS: Thirty-eight ESRD patients were converted to NHD, and included in our observational cohort study. Coronary artery calcification scores (CACS) were documented at baseline and post-conversion (mean interscan duration 16+/-1 months). Other variables of interest included age, dialysis vintage, Framingham risk profile, phosphate binder and vitamin D usage, and plasma levels of calcium, phosphate and parathyroid hormone. RESULTS: Our cohort was stratified according to baseline calcification burden (minimal calcification: CACS < or = 10 vs significant calcification: CACS > 10). Twenty-four patients had baseline CACS < or = 10. These patients demonstrated no change in coronary calcification after 1 year of NHD (from 0.7+/-0.5 to 6+/-3, P = 0.1). Fourteen patients had higher initial CACS at baseline (1874+/-696), and demonstrated a non-significant 9% increase over 1 year to 2038+/-740 (P = 0.1). Plasma phosphate and calcium x phosphate product were significantly reduced, as were calcium-based phosphate binder and antihypertensive usage. CONCLUSIONS: Our study is the first to document CACS progression in a cohort of NHD patients. Further analysis of the effect of NHD on the physiology of cardiovascular calcification is required.

Adult↗
PubMed2005

Newer paradigms in renal replacement therapy: will they alter cardiovascular outcomes?

Cardiovascular disease remains the leading cause of morbidity and mortality for patients with end-stage renal disease. Conventional hemodialysis has had limited impact on cardiovascular risk factors and mortality. Increasing evidence suggests that nocturnal home hemodialysis has beneficial effects on cardiovascular parameter outcomes. This article reviews the documented effects of nocturnal home hemodialysis on blood pressure control, cardiac geometry and left ventricular systolic function, lipid profiles, calcium-phosphate metabolism, parathyroid hormone levels, homocysteine levels, sleep apnea, and autonomic modulation of heart rate. It discusses possible mechanisms to explain these observed changes.

Cardiovascular Diseases↗
PubMed2005

Quotidian dialysis--update 2005.

PURPOSE OF REVIEW: The interest in quotidian hemodialysis has increased further after the HEMO study reported that high-dose thrice-weekly hemodialysis failed to improve clinical outcomes. This, in combination with a significant volume of newly published data, made a review of the topic of quotidian hemodialysis timely. RECENT FINDINGS: The published research has revealed further evidence of cardiovascular and quality-of-life improvements as well as financial benefits with quotidian hemodialysis. Accrued worldwide experience has confirmed the previously published benefits of quotidian hemodialysis. There has been a significant effort by industry to produce patient-friendly machines for home hemodialysis. Reports on the use of daily hemodialysis and hemodiafiltration in children have appeared. An international registry of patients on quotidian hemodialysis has been created. The need for modification of the funding mechanisms and the lack of prospective randomized controlled studies on quotidian hemodialysis led to the funding of such studies by the National Institutes of Health in collaboration with Centers for Medicare and Medicaid services to be completed by 2008. The proper funding for daily home hemodialysis was secured in the province of British Columbia, Canada, and is under consideration elsewhere. SUMMARY: There is increasing evidence confirming that quotidian hemodialysis improves clinical outcomes in a cost-efficient manner. Provided that the reimbursement issues are resolved these modalities may be utilized extensively at home as well as in the in-center facilities. The revitalization of home hemodialysis will compensate for the decline in utilization of continuous ambulatory peritoneal dialysis and the nursing shortage encountered in most countries.

Hemodialysis, Home↗
PubMed2005

Nocturnal hemodialysis increases arterial baroreflex sensitivity and compliance and normalizes blood pressure of hypertensive patients with end-stage renal disease.

BACKGROUND: Impaired neural control of heart rate, elevated arterial stiffness, and hypertension place patients with end-stage renal disease (ESRD) at increased risk of cardiovascular mortality. Nocturnal hemodialysis (6 x 8 hours/week), a more intense program than conventional hemodialysis (3 x 4 hours/week), lowers blood pressure and restores brachial dilator responses to hyperemia and nitrates. METHODS: We hypothesized that nocturnal hemodialysis would increase arterial baroreflex sensitivity for heart rate of hypertensive ESRD patients by an afferent vascular mechanism. Ten consecutive hypertensive ESRD patients (age 42 +/- 4) (mean +/- SEM) receiving conventional hemodialysis were studied before and 2 months after conversion to nocturnal hemodialysis. Regression slopes relating RR interval responses to rises or falls in systolic blood pressure were averaged to derive spontaneous baroreflex sensitivity for heart rate for each patient, and the stroke volume/pulse pressure ratio was used to estimate total arterial compliance. RESULTS: Dialysis dose (Kt/V per session) increased from 1.2 +/- 0.05 to 2.1 +/- 0.1 (P < 0.05). Despite withdrawal of antihypertensive medications (from 2.9 to 0.1 drugs/patient), nocturnal hemodialysis lowered systolic blood pressure (from 143 +/- 4 to 120 +/- 6 mm Hg) (P= 0.001). Both baroreflex sensitivity (from 4.76 +/- 1.1 msec/mm Hg to 6.91 +/- 1.1 msec/mm Hg) (P= 0.04) and total arterial compliance (from 0.98 +/- 0.13 mL/mm Hg to 1.43 +/- 0.2 mL/mm Hg) (P= 0.02) were higher following conversion to nocturnal hemodialysis. Increases in baroreflex sensitivity correlated with increases in stroke volume/pulse pressure (r= 0.845, P= 0.002). CONCLUSION: These findings are consistent with the concept that nocturnal hemodialysis increases baroreflex sensitivity via greater afferent baroreceptor responsiveness to pulsatile pressure. A more favorable risk profile, due to enhanced baroreflex regulation of the circulation and vascular compliance, may translate into lower cardiovascular event rates in ESRD patients receiving nocturnal hemodialysis.

Adult↗
PubMed2004

Review of clinical outcomes in nocturnal haemodialysis patients after renal transplantation.

BACKGROUND: Nocturnal haemodialysis (NHD) is a novel form of haemodialysis therapy that is associated with improved blood pressure control when compared to conventional haemodialysis (CHD). Current studies suggest that NHD lowers blood pressure through a decrease in peripheral resistance. The graft and blood pressure outcomes of NHD patients who undergo renal transplantation are unknown. METHODS: We reviewed the renal allograft and blood pressure outcomes of 15 NHD patients who underwent renal transplantation. An age and vintage matched cohort of 29 CHD patients was used as controls. RESULTS: The rate of delayed graft function (DGF) tended to be higher in the NHD group compared to the CHD group (64 vs 41%, P = 0.15), however the 1-year graft function (53+/-6 vs 59+/-5 ml/min, P = 0.426) and graft survival (92 vs 95%, P = 0.751) were similar. Intra-operatively, NHD patients had lower minimum systolic (92+/-5 vs 109+/-4, P = 0.03) and diastolic (48+/-3 vs 64+/-2, P = 0.02) blood pressures in comparison to the CHD cohort. Pathologically, acute tubular necrosis accounted for 100% of DGF in the NHD group in contrast to 75% in the CHD population (P = 0.01). Pre-transplant mean systolic BP (sBP) was significantly lower in the NHD group compared to the CHD group (113+/-6 vs 145+/-10 mmHg, P<0.001). At 12 months post-transplant, mean sBP increased from baseline in the NHD group ( triangle up sBP 22+/-7 mmHg, P = 0.009) while in the CHD group mean sBP fell (Delta sBP -14+/-5 mmHg, P = 0.014). Mean arterial and diastolic BP exhibited similar changes. These trends persisted after 24 months of post-transplant follow-up. CONCLUSIONS: One-year graft outcomes and blood pressures are similar for NHD and CHD patients who undergo renal transplantation. Unlike CHD patients, NHD patients experienced a significant fall in their intra-operative blood pressures, which likely contributed towards the delayed graft function in this cohort of patients. Further prospective studies are needed to examine the underlying differences in haemodynamics and long-term graft survival between the two renal replacement modalities.

Adult↗
PubMed2004

Impact of nocturnal hemodialysis on the variability of heart rate and duration of hypoxemia during sleep.

BACKGROUND: Nocturnal hemodialysis (NHD) alleviates uremia-related sleep apnea, a condition characterized by increased sympathetic activity and diminished heart rate (HR) variability. We tested the hypothesis that NHD reduces both hypoxemia and sympathetic neural contributions to HR variability during sleep. METHODS: Episodes of apnea and hypopnea and the duration of nocturnal hypoxemia during sleep were determined in 9 end-stage renal disease (ESRD) patients (age: 44 +/- 2) (mean +/- SEM) before and after conversion from conventional hemodialysis (CHD) to NHD, and in 10 control subjects (age: 45 +/- 3) with normal renal function and without sleep apnea. Low frequency (LF) (0.05-0.15 Hz) and high frequency (HF) (0.15-0.5 Hz) HR spectral power during stage 2 sleep was calculated (Fast Fourier transformation). Patients were studied 4 times (1 day before and on the night after their CHD session) and 6-15 months after conversion to NHD, while receiving NHD and on a non-dialysis night. RESULTS: NHD decreased the frequency of apnea and hypopnea (from 29.7 +/- 9.3 to 8.2 +/- 2.0 episodes per hour, P= 0.02), and duration of nocturnal hypoxemia (from 13.9 +/- 5.2 to 2.6 +/- 1.9% of total sleep time, P= 0.02). As CHD recipients, ESRD patients had faster nocturnal heart rates (79 +/- 2 vs. 58 +/- 1 min-1, P= 0.03) and lower HF (vagal) (78 +/- 27 vs. 6726 +/- 4556 ms2, P= 0.001) spectral power than control subjects. After conversion to NHD, HR fell (from 79 +/- 2 to 66 +/- 1 min-1, P= 0.03) and HF power increased (from 78 +/- 27 to 637 +/- 139 ms2, P= 0.001). The HF/HF+LF ratio, an index of vagal HR modulation, was lower during CHD (0.16 +/- 0.03 vs. 0.42 +/- 0.05 in control subjects, P < 0.05) and increased (to 0.45 +/- 0.05, P < 0.001) after conversion to NHD. The LF/HF ratio, a representation of sympathetic HR modulation, which was significantly higher during CHD than in control subjects (2.77 +/- 0.82 vs. 0.71 +/- 0.11, P < 0.05), was also normalized by NHD (0.74 +/- 0.12, P < 0.05, compared with CHD). CONCLUSION: Higher heart rates and impaired vagal and augmented sympathetic HR modulation during sleep in ESRD patients are normalized by NHD. Potential mechanisms for these observations include attenuation of surges in sympathetic outflow elicited by apnea and hypoxia during sleep, normalization of nocturnal breathing patterns that influence HRV, and removal, by increased dialysis, of a sympatho-excitatory stimulus of renal origin.

Adult↗
PubMed2004

New approaches to hemodialysis.

Treatment of end-stage renal disease with dialysis is characterized by high mortality rate, low quality of life, and high cost. Recent randomized controlled studies showed that increasing the dialysis dose above the currently recommended levels in thrice-weekly hemodialysis does not decrease the patient mortality rate. Short daily hemodialysis or daily home nocturnal hemodialysis are promising alternatives. Both improve quality of life and control blood pressure and anemia; nocturnal hemodialysis additionally controls serum phosphates without phosphate binders, allows a free diet, and corrects sleep apnea. Although the direct cost of daily hemodialysis is higher than that of conventional hemodialysis, the cost of total care, especially when delivered at home, seems to be lower. Further confirmation of these results is important. Restructuring of the dialysis reimbursement system is necessary to make the use of daily hemodialysis possible. Hemofiltration techniques, sorbents, and the renal tubular assist device may also help change the current grim statistics.

Humans↗
PubMed2003

Short-term blood pressure, noradrenergic, and vascular effects of nocturnal home hemodialysis.

Long-term nocturnal hemodialysis, which uses longer and more frequent sessions than conventional hemodialysis, lowers clinic blood pressure and left ventricular mass. We tested the hypotheses that short-term nocturnal hemodialysis would (1) reduce ambulatory blood pressure; (2) cause peripheral vasodilation; (3) lower plasma norepinephrine concentration; and (4) improve the arterial response to reactive hyperemia (a marker of endothelium-dependent vasodilation). We studied 18 consecutive patients (age, 41+/-2; [mean+/-SEM]) before and 1 and 2 months after conversion from conventional (three 4-hour sessions per week) to nocturnal (six 8-hour sessions per week) hemodialysis. As the dialysis dose per session (Kt/V) increased from 1.24+/-0.06 to 2.04+/-0.08 after 2 months (P=0.02), symptomatic hypotension developed and most antihypertensive medications were withdrawn. Nocturnal hemodialysis nonetheless lowered 24-hour mean arterial pressure (from 102+/-3 to 90+/-2 mm Hg after 2 months; P=0.01), total peripheral resistance (from 1967+/-235 to 1499+/-191 dyne x s x cm(-5); P<0.01) and plasma norepinephrine (from 2.66+/-0.4 to 1.96+/-0.2 nmol; P=0.04). Endothelium-dependent vasodilation could not be elicited during conventional hemodialysis (-2.7+/-1.8%) but was restored (+8.0+/-1.0%; P=0.001) after 2 months of nocturnal hemodialysis. The brachial artery response to nitroglycerin also improved (from 6.9+/-2.8 to 15.7+/-1.6%; P<0.05). Nocturnal hemodialysis had no effect on weight or on stroke volume. Rapid reversal of these markers of adverse cardiovascular events with more intense hemodialysis may translate into improved outcome in this high-risk group of patients.

Adult↗
PubMed2003

The quality of life and cost utility of home nocturnal and conventional in-center hemodialysis.

BACKGROUND: Home nocturnal hemodialysis is an intensive form of hemodialysis, where patients perform their treatments at home for about 7 hours approximately 6 nights a week. Compared with in-center conventional hemodialysis, home nocturnal hemodialysis has been shown to improve physiologic parameters and reduce health care costs; however, the effects on quality of life and cost utility are less clear. We hypothesized that individuals performing home nocturnal hemodialysis would have a higher quality of life and superior cost utility than in-center hemodialysis patients. METHODS: Home nocturnal hemodialysis patients and a demographically similar group of in-center hemodialysis patients from a hospital without a home hemodialysis program underwent computer-assisted interviews to assess their utility score for current health by the standard gamble method. RESULTS: Nineteen in-center hemodialysis and 24 home nocturnal hemodialysis patients were interviewed. Mean annual costs for home nocturnal hemodialysis were about 10,000 dollars lower for home nocturnal hemodialysis (55,139 dollars +/- 7651 dollars for home nocturnal hemodialysis vs. 66,367 dollars +/- 17,502 dollars for in-center hemodialysis, P = 0.03). Home nocturnal hemodialysis was associated with a higher utility score than in-center hemodialysis (0.77 +/- 0.23 vs. 0.53 +/- 0.35, P = 0.03). The cost utility for home nocturnal hemodialysis was 71,443 dollars/quality-adjusted life-year (QALY), while for in-center hemodialysis it was 125,845 dollars/QALY. Home nocturnal hemodialysis was the dominant strategy, with an incremental cost-effectiveness ratio (ICER) of -45,932 dollars. The 95% CI for the ICER, and 2500 bootstrap iterations of the ICER all fell below the cost-effectiveness ceiling of 50,000 dollars. The net monetary benefit of home nocturnal hemodialysis ranged from 11,227 dollars to 35,669 dollars. CONCLUSION: Home nocturnal hemodialysis is associated with a higher quality of life and a superior cost utility when compared to in-center hemodialysis.

Adult↗
PubMed2003

Daytime sleepiness in patients with CRF: impact of nocturnal hemodialysis.

BACKGROUND: Patients with end-stage renal disease (ESRD) have a high prevalence of sleep disorders, which are not improved by conventional hemodialysis (CHD). Although sleep disorders are commonly associated with complaints of excessive daytime sleepiness, the severity and pathogenesis of daytime sleepiness has not been evaluated objectively in patients with ESRD. Nocturnal hemodialysis (NHD) is a new technique that provides better clearance of uremic toxins than CHD and, consequently, may improve sleep quality and daytime sleepiness. The authors wished to determine the severity and pathogenesis of daytime sleepiness in patients with ESRD and evaluate the impact of NHD. METHODS: Sleep quality was monitored by overnight polysomnography, and daytime sleepiness was assessed by the multiple sleep latency test (MSLT). These measurements were performed in 24 patients (15 men and 9 women, 44 +/- 10 years) while on treatment with CHD and were repeated in 15 patients after conversion to NHD. RESULTS: The majority (54%) of patients on CHD were pathologically sleepy (somnolent group, mean sleep latency <5 minutes), and, in comparison with the remaining patients (alert group, mean sleep latency >5 minutes), their blood urea nitrogen (BUN; 77.9 +/- 9.8 v 60.2 +/- 12.0 mg/dL, P < 0.001; 27.8 +/- 3.5 v 21.5 +/- 4.3 mmol/L; P < 0.001), and periodic limb movement (PLM) index (57 +/- 47 v 6 +/- 10/hr; P = 0.002) were significantly higher. Furthermore, sleep latency was correlated with BUN (R = 0.58, P = 0.008). After conversion to NHD, there was a significant fall in BUN and the severity of sleep apnea, but the overall frequency of PLM and sleep fragmentation remained elevated. Nevertheless, there was a trend for the Somnolent group to become less sleepy on NHD, and this was associated with a modest reduction in the frequency of PLM. CONCLUSION: Excessive daytime sleepiness occurs in approximately 50% of patients with ESRD. The etiology appears to be related both to uremia and sleep fragmentation associated with PLM.

Adult↗
PubMed2003

Resolution of massive uremic tumoral calcinosis with daily nocturnal home hemodialysis.

BACKGROUND: Derangements in bone mineral metabolism are an invariable consequence of end-stage renal disease (ESRD). Extraosseous tumoral calcification is a relatively uncommon complication that can be associated with substantial morbidity. METHODS: The authors report a case of an ESRD patient who had severe tumoral calcification of his shoulder, hands, and feet despite daily conventional hemodialysis. Conversion to daily nocturnal hemodialysis (DNHD) led to a dramatic resolution of his calcific deposits within only 9 months of initiating this form of renal replacement therapy. RESULTS: After initiating DNHD, the patient's serum phosphate level, which had been exceedingly difficult to control, normalized within the first week. Despite maintaining a high dialysate calcium (Ca) bath up to 4.2 mEq/L (2.1 mmol/L; to maintain calcium balance and suppress parathyroid hormone [PTH]), there was ongoing dissolution of the calcific deposits. This occurred with relatively preserved bone mineral density. The Ca x phosphorus (PO4) product decreased from 85 mg2/dL2 (6.80 mmol2/L2) and remained less than 55 mg2/dL2 (4.4 mmol2/L2) throughout the patient's course on DNHD. PTH levels fell precipitously early on but then rose again several months after starting DNHD. This PTH rebound as well as the possible mechanisms underlying the dissolution of this patient's extraosseous calcifications are explored further. CONCLUSION: Extraosseous tumoral calcification associated with ESRD is an uncommon but potentially serious complication in this patient population. DNHD, by offering superior phosphate clearance, can facilitate the dissolution of these calcific deposits over a relatively short period. This effect can be seen despite using high calcium concentration dialysate to maintain calcium balance and mitigate hyperparathyroidism.

Absorptiometry, Photon↗
PubMed2002

Regression of left ventricular hypertrophy after conversion to nocturnal hemodialysis.

BACKGROUND: Left ventricular hypertrophy (LVH) is an independent risk factor for mortality in the dialysis population. LVH has been attributed to several factors, including hypertension, excess extracellular fluid (ECF) volume, anemia and uremia. Nocturnal hemodialysis is a novel renal replacement therapy that appears to improve blood pressure control. METHODS: This observational cohort study assessed the impact on LVH of conversion from conventional hemodialysis (CHD) to nocturnal hemodialysis (NHD). In 28 patients (mean age 44 +/- 7 years) receiving NHD for at least two years (mean duration 3.4 +/- 1.2 years), blood pressure (BP), hemoglobin (Hb), ECF volume (single-frequency bioelectrical impedance) and left ventricular mass index (LVMI) were determined before and after conversion. For comparison, 13 control patients (mean age 52 +/- 15 years) who remained on self-care home CHD for one year or more (mean duration 2.8 +/- 1.8 years) were studied also. Serial measurements of BP, Hb and LVMI were also obtained in this control group. RESULTS: There were no significant differences between the two cohorts with respect to age, use of antihypertensive medications, Hb, BP or LVMI at baseline. After transfer from CHD to NHD, there were significant reductions in systolic, diastolic and pulse pressure (from 145 +/- 20 to 122 +/- 13 mm Hg, P < 0.001; from 84 +/- 15 to 74 +/- 12 mm Hg, P = 0.02; from 61 +/- 12 to 49 +/- 12 mm Hg, P = 0.002, respectively) and LVMI (from 147 +/- 42 to 114 +/- 40 g/m2, P = 0.004). There was also a significant reduction in the number of prescribed antihypertensive medications (from 1.8 to 0.3, P < 0.001) and an increase in Hb in the NHD cohort. Post-dialysis ECF volume did not change. LVMI correlated with systolic blood pressure (r = 0.6, P = 0.001) during nocturnal hemodialysis. There was no relationship between changes in LVMI and changes in BP or Hb. In contrast, there were no changes in BP, Hb or LVMI in the CHD cohort over the same time period. CONCLUSIONS: Reductions in BP with NHD are accompanied by regression of LVH.

Aged↗