To the Editor, La glomerulonefritis membranosa Membranous glomerulonephritis (MGN) is the second most prevalent renal pathology to be identified in biopsies. One of the most common causes of nephrotic syndrome in the adult population, it is characterised by the formation of immune complexes, predominantly IgG and complement, on the subepithelial side of the glomerular capillaries, and this is associated with increased proteinuria.

Introduction and Aims: On-line dialysance (Kt) and thermodilution (BTM-Qa) methods could be important components in vascular access monitoring programs.This study evaluated the efficiency of these two methods in reducing the thrombosis rate and access-related costs compared with a historic control group.Methods: We studied 148 long-term hemodialysis patients with arteriovenous fistulas (historical control group, n = 74) for 2 years.During the study period, the indications for vascular treatments were the Kt reduction ≥20% with respect to baseline values or Qa less than 500 mL/min (or a decrease in flow > 20%).Differences between the Qa and Kt groups were tested using Student's T-Test or the Wilcoxon test, as appropriate.The χ2 test was used to analyze the angioplasty and thrombosis rates compared with the historical control group.A P-value ≤0.05 was considered statistically significant.Results: During the study period, we detected 16 cases of significant vascular access dysfunction.The Kt value after vascular treatment was 71.1L (59L; P = 0.001) and BTM-Qa was 1218.6 mL/min (519.7 mL/min; P = 0.001).Compared with the control group, the thrombosis rate was 0.027 vs 0.148 episodes/patient-year (P = 0.009) and the total access-related cost was €22,293 vs €47,467 (P = 0.033).Conclusions: This study suggests that a combined monitoring program based on Kt and Qa-BTM represents an effective screening method that significantly reduces the thrombosis rate and economic costs of vascular treatments SP523

Cephalic arch stenosis (CAS) is a unique type of vascular access stenosis. For example, the etiology of CAS is under investigation and the prevalence of CAS can be lower in diabetic patients. Three cases of CAS were identified during our vascular access stenosis surveillance program by blood flow rate measurements using the Delta-H method. We evaluated the prevalence, etiology, relationship with diabetes and functional profile of CAS. To date, this is the first functional report published about this type of stenosis.

INTRODUCTION:Vascular calcification is a common finding in patients (pts) with end-stage renal disease (ESRD). OBJECTIVE:The aim of this cross-sectional study was to investigate the prevalence and functional effect of native arteriovenous fistula AVF (feeding artery and/or arterialized vein) calcifications evaluated by spiral computed tomography (CT) in ESRD pts undergoing chronic hemodialysis (HD). PATIENTS AND METHOD:Forty-five upper limb AVF (radial 44.4% or brachial 55.6%, mean duration 65.3 +/- 80.9 months) without evidence of significant stenosis were evaluated by CT in 45 ESRD pts (mean age 63.8 +/- 13.1 yr; sex M: 71.1%, F: 28.9%; mean time on HD 53.1 +/- 51.9 months; diabetic nephropathy 15.6%). All AVF explorations were performed using the same multi-slice spiral CT scanner (HiSpeed Dual machine, GE Medical Systems). The severity of AVF calcifications was quantified by CT using the following criteria: grade I absence of calcifications, grade II isolated calcifications (<10 groups of calcification), grade III moderate calcifications (10-20 groups of calcification) and grade IV diffuse calcifications (>20 groups of calcification). Laboratory parameters analyzed: calcium, phosphorus, parathyroid hormone; calcium x phosphorus product was calculated. The same week of CT scanning, we evaluated AVF function measuring the blood flow rate (QA). We determined QA (1559.3 +/- 980.6 ml/min) by the Delta-H method (ABF-mode, HemaMetrics, USA) using the Crit-Line III monitor (68.9%) or by Doppler ultrasound (31.1%) performed by the same radiologist using a 5-8 MHz linear transducer (Sequoia machine, Siemens-Acuson); mean arterial pressure MAP (94.7 +/- 16.3 mmHg) was recorded simultaneous with QA. RESULTS:Most pts not showed AVF calcification by CT scan (grade I: 27/45, 60%). Forty percent of pts (18/45) demonstrated any degree of AVF calcification (grade II 13.3%, grade III 8.9%, grade IV 17.8%). Pts with brachial AVF showed higher mean QA compared to pts with radial AVF (1899.1 +/- 1131.8 versus 1134.5 +/- 516.4 ml/min, p=0.005), but MAP (91.2 +/- 15.8 versus 99.0 +/- 16.2 mmHg) and the prevalence of AVF calcification (32% versus 50%) were not different between both groups (p=0.11 and p=0.24, respectively). Pts with evidence of any calcification on CT scanning (grade II, III or IV) had higher time on HD (84.6 +/- 63.1 versus 24.6 +/- 20.0 months), higher AVF duration (97.7 +/- 89.3 versus 34.6 +/- 61.2 months) and similar QA (1488.3 +/- 678.9 versus 1606.6 +/- 1148.9 ml/min) compared with pts without AVF calcification (p=0.014, p=0.001 and p=0.69, respectively); no differences in MAP (95.4 +/- 13.8 versus 94.2 +/- 17.9 mmHg), prevalence of brachial AVF (44% versus 63%) or mineral metabolism parameters were found when comparing both groups (for all comparisons, p=NS). The same results were obtained when comparing pts with a high (grade III-IV: 26.7%) and a low (grade I-II: 73.3%) AVF calcification score, or when comparing pts with diffuse (grade IV) and without (grade I) AVF calcification. CONCLUSIONS:1) The prevalence of AVF calcification by CT scan was 40%. 2) The AVF calcification was related with time on HD and AVF duration. 3) The function of fully developed AVF without stenosis and suitable for routine HD was not impaired by the presence of calcifications.

INTRODUCTION:Periodic QA measurement is the preferred way for VA surveillance in end-stage renal disease (ESRD) patients (pts). OBJECTIVE:The aims of this study were to measure QA by TDT and to compare the functional results with Delta-H method. PATIENTS AND METHODS:We measured Q(A) non invasively in 38 VA (mean VA duration: 48.7 +/- 69.8 months) during HD in 38 stable ESRD (mean age 63.8 +/- 15.1 yr, mean time on HD 47.6 +/- 53.9 months, diabetic nephropathy 18.4%) pts by the TDT. Fourteen pts (36.8%) had history of previous VA that were ipsilateral to the VA under study in most cases (11/14, 78.6%). Thirteen pts (34.2%) had history of any comorbidity (coronary artery or cerebrovascular or peripheral vascular diseases). Q(A) was calculated from the recirculation values obtained by means of the blood temperature monitor (BTM), integrated into the Fresenius Medical Care 4008-S machine, at normal and reverse configurations of the HD blood lines. Q(A) was measured within the first hour of two consecutive HD sessions (the values were averaged). Mean arterial pressure MAP and distance between needles (DBN) were measured simultaneous with Q(A). In addition, the VA blood flow was also determined by Delta-H method using Crit-Line III Monitor (ABF-) between 1000 and 1500 ml/min. The mean DBN and MAP were 6.2 +/- 2.9 cm, 91.9 +/- 12.4 mmHg, respectively. Mean Q(A) was similar for pts with mean MAP<100 mmHg (n=26) and for pts with mean MAP>or=100 mmHg (n=12) (p=0.85). Pts with diabetic nephropathy showed lower mean Q(A) (836.1 +/- 395.8 ml/min) compared to the remaining pts (1,245.9 +/- 449.9 ml/min) (p=0.033). No differences in mean Q(A) was found when pts with any comorbidity and without comorbidities were compared (p=0.62). Brachial AVF tended to have higher mean Q(A) (1,323.6 +/- 465.3 ml/min) compared to radial AVF (1,017.4 +/- 447.3 ml/min) (p=0.052). Pts with history of previous VA showed higher mean Q(A) (1,410.6 +/- 377.7 ml/min) compared to the remaining pts (1,030.4 +/- 458.7 ml/min) (p=0.013). No correlation was found between mean Q(A) and: mean age, DBN, MAP, Kt/V index, time on HD and VA duration. Mean Q(A) obtained by TDT was not different when compared with mean ABF determined by Delta-H method (1,151.3 +/- 479.0 ml/min) (p=0.89). The calculated values of VA blood flow obtained by TDT were highly correlated with those determined by the Delta-H method (intraclass correlation coefficient =0.95, p<0.001). CONCLUSIONS:The TDT is an indicator of QA during HD. The functional profile of VA was worse in pts with diabetic nephropathy or without history of previous VA. The VA blood flow values obtained by TDT and Delta-H techniques correlated highly with each other.

INTRODUCTION The CDU is a noninvasive vascular access (VA) monitoring technique that provides both structural and hemodynamic information from vessels. OBJECTIVE The aim of this prospective study was to analyze some parameters of forearm vessels by CDU before and after RCF creation at the wrist. PATIENTS AND METHODS We explored by CDU the vessels of forearm in 34 CRF patients (pts) (mean age 63.915.1 yr, sex M:76.5%;F:23.5%, 26.5% diabetes, 73.5% already on HD at the time of RCF placement). Forearm CDU evaluation was planned twice: before RCF creation (first exploration FE) and after two months of successful RCF cannulation for HD by 2 needles at Qb>250 ml/min (second exploration SE). All CDU examinations were performed by the same radiologist with 5-10 MHz linear transducer (Doppler angle < or = 60 degrees) at two proximal and distal points of the forearm (the values were averaged) using the Aspen machine (Siemens-Acuson, Mountain View, CA). We measured by CDU parameters from radial artery RA (diameter RAd, peak systolic velocity PSV, resistive index RI, blood flow rate RAflow), cephalic vein CV (diameter CVd) and arterialized vein AV (diameter AVd, blood flow rate AVflow). RAflow or AVflow calculation by CDU: time average velocity (mean of three cardiac cycles) (m/s) x cross-sectional area (mm2) x 60. RCF outcome: functioning RCF (FRCF) suitable for routine HD 61.8% (mean age 61.214.5 yr, 23.8% diabetes), or non-functioning RCF 38.2% (mean age 68.215.5 yr, 30.8% diabetes) due to: early thrombosis (within 24 hours after operation, ETRCF) 14.7%, lack of RCF maturation (LMRCF) 5.9%, last thrombosis (between 24 hours after operation and SE by CDU, LTRCF) 17.6%. RESULTS Between FE and SE by CDU at RA, overall mean RAd (3.2 +/- 0.3 vs 5.5 +/- 1.0 mm), mean PSV (59.9 +/- 12.4 vs 166.6 +/- 58.2 cm/s) and mean RAflow (67.9 +/- 27.4 vs 1297.1 +/- 683.1 ml/min) increased significantly (for all comparisons, p<0.001), and mean RI (0.9 +/- 0.2 vs 0.40. +/- 0.1) decreased significantly (p<0.001); we also found a significant difference when overall mean CVd (2.9 +/- 0.6 mm) and mean AVd (5.7 +/- 1.1 mm) were compared (p<0.001). Overall and distal mean RAflow at FE by CDU were lower in pts with ETRCF (33.6 +/- 19.6 and 26.0 +/- 16.7 ml/min, respectively) compared to pts with FRCF (67.9 +/- 27.4 and 48.0 +/- 21.3 ml/min, respectively) (p=0.015 and p=0.029, respectively). Pts with ETRCF and LMRCF considered together (20.6%), had lower overall mean RAd (2.80.4 mm) and distal mean RAflow (28.1 +/ 15.2 ml/min) at FE by CDU compared to pts with FRCF (3.2 +/ 0.3 mm and 48.0 +/- 21.3 ml/min, respectively) (p=0.015 and p=0.031, respectively). No significant differences between pts with LTRCF and FRCF were found when overall and distal mean RAd, PSV, RI, RAflow and CVd obtained at FE by CDU were compared (for all comparisons, p=NS), but all pts with LTRCF underwent HD at the time of RCF creation compared to 57.1% of pts with FRCF (p=0.049). Pts with FRCF who had overall mean AVflow = 800 ml/min (38.1%, mean AVflow: 602.5167.3 ml/min) showed lower overall mean RAflow at SE by CDU compared to pts with FRCF who had overall mean AVflow>800 ml/min (61.9%, mean AVflow: 1113.9 +/- 160.1 ml/min): 820.1 +/- 188.7 vs 1590.7 +/- 715.4 ml/min (p=0.002). We found a positive correlation between overall mean AVflow and mean RAflow obtained at SE by CDU (r = 0.52, p = 0.016). CONCLUSIONS 1) All parameters of forearm vessels measured by CDU changed after RCF placement. 2) Preoperative mean RAflow is predictive of RCF outcome. 3) Mean AVflow is related to mean RAflow obtained at SE by CDU.

Purpose To evaluate the functional effects of preventive vascular access (VA) intervention through periodic blood flow (QA) measurements during hemodialysis (HD) by the delta-H method. Methods We prospectively monitored the blood flow rate (QA) of 100 VA (arteriovenous fistula (AVF) 81% or AV graft (AVG) 19%; mean VA duration 24.6 ± 42.3 months) during HD in 89 end-stage renal disease patients (mean age 62.7 ± 13.6 yrs; mean time on HD 30.9 ± 43.9 months; 18% with diabetes) over a 3-yr period. QA was measured at least every 4 months by the delta-H method (Yarar (6)) using the Crit Line III Monitor (overall mean QA 1247.6 ± 519.7 ml/min). The mean arterial pressure (MAP) and Kt/V index were measured simultaneously with QA. Thirty-eight VA (38%) met the positive evaluation criteria (absolute QA <700 ml/min 50%, QA decreased >20% from baseline 50%). Most cases with positive evaluation underwent angiography (36/38, 95%) and had stenosis ≥50% (34/36, 94%). Of VA with significant stenosis, 17 (17/34, 50%) VA (AVF 76.5%, AVG 23.5%; mean VA duration 12.5 ± 22.4 months, mean percentage of VA stenosis 75.8%) in 15 patients (mean age 68.4 ± 9.8 yrs; mean time on HD 14.2 ± 18.2 months; 33.3% with diabetes) underwent corrective intervention by angioplasty, 35.3% (6/17), and revision surgery, 64.7% (11/17). Results Short-term results: Elective intervention was successful in 88% of treated VA (15/17). Mean QA increased from 563.8 ± 115.4 ml/min just before intervention (QA pre) to 975.7 ± 351.8 ml/min just after intervention (QA post) (mean ΔQA = 411.8 ± 290.1 ml/min) (p < 0.001). We found a significant difference between the overall mean QA before (689.6 ± 227.0 ml/min) vs after intervention (965.9 ± 396.8 ml/min) (p = 0.011). No difference was found when the highest recorded mean QA before intervention (877.7 ± 415.4 ml/min) and mean QA post were compared (p = 0.25). Mean MAP did not change after intervention (91.5 ± 12.5 vs 92.7 ± 14.2 mmHg, p = 0.46). Mean Kt/V index improved from 1.44 ± 0.24 just before intervention to 1.49 ± 0.23 just after intervention without any change in dialyzer type or HD duration (p = 0.025). Mean ΔQA was similar for diabetic patients vs non-diabetic patients (p = 0.34), for younger patients (age < 65 yrs) vs older patients (age ≥65 yrs) (p = 0.64) and for AVF vs AVG (p = 0.39). We found a positive correlation between mean ΔQA and mean QA post (r = 0.95, p < 0.001) or between mean ΔQA and overall mean QA after intervention (r = 0.77, p < 0.001). Long-term results Prevalence of VA thrombosis during the follow-up period (354.4 ± 293.1 days): 17.6% (3/17). Five (29.4%) treated VA showed restenosis and two of them (40%) underwent reintervention by surgery. Mean restenosis period and mean decrease in QA were 232.6 ± 74.1 days and 2.8 ± 0.6 ml/min/day, respectively. No significant correlation was found between mean ΔQA or QA pre and mean restenosis period or decrease in QA (p = ns). Conclusions 1) Monitoring QA by the delta-H method is useful in assessing the hemodynamic response to elective VA intervention. 2) Mean QA post was similar to the highest recorded mean QA before intervention. 3) Mean ΔQA was related to mean QA post and overall mean QA after intervention. 4) The HD effectiveness (Kt/V index) improved after intervention.

Placement, Performance and complications of The Tesio Twin Tunnelled Catheter System for hemodialysis Purpose: Review a large experience in the placement of tunnelled catheters to assess the outcomes with Twin catheter System as hemodialysis access. Material and Methods: We retrospectively reviewed clinical and hemodialysis data regarding of ESRD patients who were referred from 2 dialysis facilities for placement of tunnelled catheter as hemodialysis access between 1996 march and 2005 july. For catheter insertion it was used a real-time sonography technique (Site Rite II Dymax corporation) in performing vascular access procedure. The twin catheter system available during the study period consisted of 2x10-F12. Patients suspected to present bacteraemia related to catheter were followed with established protocols. Catheter suspected malfunction or thrombosis was treated with low dose Urokinase. To evaluated dialysis dose and adequacy, blood flow rates were recorded and Kt/v calculated by Daugirdas 2(nd) generation formula. Results: Over all study period of 112 months, 2 10 catheters were inserted in 148 patients (93 males and 55 females, mean age 68,6 4,95 years). 101 catheters were inserted in internal jugular vein, 84 in femoral and 25 in subclavian. The successful insertion rate with only single needle pass was 87,8%, immediate procedural complications rate was 4.7%. The catheters were in place a total of 18,324 days during the study period (mean 87,2 days; range 4-1,280 days). The mean flow blood rate was 252,4 DS +/- 42.4 mL/min, Mean Kt/v was 1,21 DS +/- 0,07. Seventy -seven Catheters malfunctioned during study period, in 55 cases urokinase was effective in recovering blood flow rate over 250 mL/min and 25 were necessitated removal for ineffective urokinase. Infection incidence was 11.9% with bacteraemia related catheter rate of 2.8 episodes per 1,000 catheter-days, Gram positive bacteria was found in (84%), Cram negative in (12%) and others (4%). Conclusion: Placement of Tunnelled twin catheters system using real-time sonografy technique can be performed with excellent technical success, safety and acceptable catheter performance and outcomes for effective hemodialysis.

The aim of this study was to know the prevalence and functional profile of RA stenosis in RCF dysfunction detected as a result of our surveillance programme.We prospectively monitored QA of 116 VA (arteriovenous fistula 81% or graft 19%; mean VA duration 28.2 +/- 52.9 months) during hemodiaysis (HD) in 102 ESRD (mean age 63.0 +/- 13.0 yr; sex M: 56.9%, F: 43.1%; mean time on HD 31.4 +/- 44.0 months; 15.5% diabetes) patients (pts) over 4 yr period. QA was measured at least every 4 months by the Delta-H method using the Crit-Line III monitor (overall mean QA 1,193.4 +/- 490.3 ml/min) Forty-three VA (43/116, 37%) met criteria of positive evaluation (absolute QA < 700 ml/min: 48.8%; NQA > 20% from baseline: 51.2%) and were referred for angiography. Most VA explored by angiography showed stenosis > or = 50% (36/40, 90%) that were mainly located in RCF (25/36, 69.4%: RA 11/25, arterialized vein AV 14/25).Eleven cases of RA stenosis (prevalence: 11/36, 30.5%; mean degree: 83.5 +/- 15.8%) were found in 11 RCF (mean VA duration 48.9 +/- 76.7 months) of 11 pts (mean age 67.5 +/- 11.5 yr; mean time on HD 54.0 +/- 75.8 months; 18.2% diabetes). Cause of positive evaluation: absolute QA < 700 ml/min 81.8%; NQA > 20% from baseline 18.2%. Mean QA of RCF just before angiography: 532.9 +/- 99.8 ml/min (range, 418-699 ml/min). Stenosis type: Type I (multiple stenoses) 9.1%, type II (isolated stenosis but critical > 90-95%) 36.4% and type III (isolated stenosis 50-90% with normal haemodynamic status of RCF) 54.5%. Followup: stenosis not reparable 36.4% (4/11), elective intervention by surgery 36.4% (4/11), lost of follow-up before intervention 27.3% (2/11 died, 1/11 transplantation). Mean QA of RCF tended to increase from 547.0 +/- 100.6 ml/min just before surgery to 872.3 +/- 526.5 ml/min just after surgery (n = 4, mean DQA = 325.2 +/- 431.3 ml/min (p = 0.068). Comparative study with 14 AV stenosis (mean degree 76.4 +/- 7.4%) in 11 RCF (mean VA duration 16.4 +/- 22.8 months) of 11 pts (mean age 64.3 +/- 10.5 yr; mean time on HD 17.0 +/- 18.9 months; 50% diabetes): higher prevalence of intervention (85.8%) compared to RA stenosis (p =0.011); without differences in degree of stenosis (p = 0.12) and QA before angiography (p = 0.78) or surgery (p = 1.00); mean QA increased significantly after surgery (n = 6 AV, 549.8 +/- 86.4 vs 1,033.0 +/- 216.6 ml/min) (p = 0.028).1) One third of cases of VA dysfunction were related to feeding artery stenosis. 2) No differences in functional profile were found between RA and AV stenosis before angiography and surgery. 3) The functional results of elective surgery in RA stenosis were worse compared to AV stenosis.

Objective: The aim of this study was to know the prevalence and functional profile of RA stenosis in RCF dysfunction detected as a result of our surveillance programme. Patients and methods: We prospectively monitored Q(A) of 116 VA (arteriovenous fistula 81% or graft 19%; mean VA duration 28.2 +/- 52.9 months) during hemodiaysis (HD) in 102 ESRD (mean age 63.0 +/- 13.0 yr, sex M: 56.9%, F: 43.1%; mean time on HD 31.4 +/- 44.0 months; 15.5% diabetes) patients (pts) over 4 yr period. Q(A) was measured at least every 4 months by the Delta-H method using the Crit-Line III monitor (overall mean QA 1193.4 +/- 490.3 ml/min) Forty-three VA (43/116, 37%) met criteria of positive evaluation (absolute Q(A) < 700 ml/min: 48.8%; del Q(A) > 20% from baseline: 51.2%) and were referred for angiography. Most VA explored by angiography showed stenosis >= 50% (36/40, 90%) that were mainly located in RCF (25/36, 69.4%: RA 11/25, arterialized vein AV 14/25). Results: Eleven cases of RA stenosis (prevalence: 11/36, 30.5%; mean degree: 83.5 15.8%) were found in 11 RCF (mean VA duration 48.9 +/- 76.7 months) of 11 pts (mean age 67.5 +/- 11.5 yr; mean time on HD 54.0 +/- 75.8 months; 18.2% diabetes). Cause of positive evaluation: absolute Q(A) < 700 ml/min 81.8%; del Q(A) > 20% from baseline 18.2%. Mean Q(A) of RCF just before angiography: 532.9 +/- 99.8 ml/min (range, 418-699 ml/min). Stenosis type: Type I (multiple stenoses) 9.1%, type II (isolated stenosis but critical > 90-95%) 36.4% and type III (isolated stenosis 50-90% with normal haemodynamic status of RCF) 54.5%. Followup: stenosis not reparable 36.4% (4111), elective intervention by surgery 36.4% (4/11), lost of follow-up before intervention 27.3% (2/11 died, 1/11 transplantation). Mean Q(A) of RCF tended to increase from 547.0 +/- 100.6 ml/min just before surgery to 872.3 +/- 526.5 ml/min just after surgery (n = 4, mean Delta Q(A) = 325.2 +/- 431.3 ml/min (p = 0.068). Comparative study with 74 AV stenosis (mean degree 76.4 +/- 7.4%) in 11 RCF (mean VA duration 76.4 +/- 22.8 months) of 11 pts (mean age 64.3 +/- 10.5 yr; mean time on HD 17.0 +/- 18.9 months; 50% diabetes): higher prevalence of intervention (85.8%) compared to RA stenosis (p = 0.011); without differences in degree of stenosis (p = 0.12), Delta Q(A) (p = 0.20) and Q(A) before angiography (p = 0.78) or surgery (p = 1.00); mean QA increased significantly after surgery (n 6 AV, 549.8 +/- 86.4 vs 1033.0 +/- 216.6 ml/min) (p = 0.028). Conclusions: 1) One third of cases of VA dysfunction were related to feeding artery stenosis. 2) No differences in functional profile were found between RA and AV stenosis before angiography and surgery. 3) The functional results of elective surgery in RA stenosis were worse compared to AV stenosis.

PURPOSE:Review a large experience in the placement of tunnelled catheters to assess the outcomes with twin catheter system as hemodialysis access.MATERIAL AND METHODS:We retrospectively reviewed clinical and hemodialysis data regarding of ESRD patients who were referred from 2 dialysis facilities for placement of tunnelled catheters hemodialysis access between 1996 March and 2005 July. For catheter insertion a real-time sonography technique was used (Site Rite II Dymax corporation) in performing vascular access procedure. The twin catheter system available during the study period consisted of 2 x 10-F12. Patients suspected to present bacteraemia related to catheter were followed with established protocols. Catheter suspected malfunction or thrombosis was treated with low dose Urokinase. To evaluated dialysis dose and adequacy, blood flow rates were recorded and Kt/v calculated by Daugirdas 2nd generation formula.RESULTS:Overall study period of 112 months, 210 catheters were inserted in 148 patients(93 males and 55 females, mean age 68,6 +/- 4,95 years). 101 catheters were inserted in internal jugular vein, 84 in femoral and 25 in subclavian. The successful insertion rate with only single needle pass was 87.8%, immediate procedural complications rate was 4.7%. The catheters were in place a total of 18,324 days during the study period (mean 87.2 days; range 4-1,280 days). The mean flow blood rate was 252,4 DS +/- 42.4 mL/min, Mean Kt/v was 1,21 DS +/- 0,07. Seventy-seven catheters malfunctioned during study period, in 55 cases urokinase was effective in recovering blood flow rate over 250 mL/min and 25 necessitated removal for ineffective urokinase. Infection incidence was 11.9% with bacteraemia related catheter rate of 2.8 episodes per 1,000 catheter-days, Gram positive bacteria was found in (84%), Gram negative in (12%) and others(4%).CONCLUSION:Placement of tunnelled twin catheters system using real-time sonography technique can be performed with excellent technical success, safety and acceptable catheter performance and outcomes for effective hemodialysis.

INTRODUCTION The color Doppler ultrasonography (CDU) is a noninvasive vascular access (VA) monitoring technique that provides both structural and hemodynamic information from VA. On the other hand, the delta-H (AH) method is another noninvasive technique that measures the VA blood flow rate during hemodialysis (HD). OBJECTIVE 1) To analyze some anatomic and functional parameters of VA by CDU. 2) To compare AH and CDU methods in measuring VA blood flow rate. PATIENTS AND METHODS We explored the VA (radial arteriovenous fistula AVF 60.6%, brachial AVF 24.2%, femoral graft 15.2%; mean VA duration 33.5 +/- 31.5 months) of 33 stable ESRD (mean age 61.7 +/- 13.3 yr, sex M: 48.5%; F: 51.5%; mean time on hemodialysis HD 39.3 +/- 33.3 months; 9.1% diabetes) patients (pts) by CDU over 3 months period. All CDU examinations were performed off HD by the same radiologist using a 5-10 MHz linear transducer. The arterial and venous blood flow rates were calculated by CDU using the equation: flow (ml/min) = time average velocity (mean of three cardiac cycles) (m/s) x cross-sectional area (mm2) x 60. No VA explored had any sign of dysfunction prior to CDU evaluation. All pts with significant VA stenosis by CDU (> or = 50% reduction in the luminal diameter) were referred for angiography (AG). All functional parameters were measured in duplicate and the values were averaged. In addition, QA was also calculated in the same week by the deltaH method during HD using the Crit Line III Monitor. RESULTS Feeding artery (FA) results. Mean FA diameter (FAd): 0.7 +/- 0.2 cm. Mean peak systolic velocity: 161.8 +/- 44.5 m/s. Mean FA blood flow rate (FA flow) (n = 27): 2,030.8 +/-987.1 ml/min. We found a positive correlation between mean FA flow and mean FAd (R2 = 0.39, p < 0.001). Arterialized vein (AV) results. Mean AV diameter (AVd): 0.7 +/- 0.2 cm. Mean AV blood flow rate (AVflow): 1,783.8 +/- 1,009.7 ml/min (range, 398-5,843 ml/min). Mean coefficient of variation for duplicate AV flow measurements: 9.2%. We found a positive correlation between mean AV flow and: mean FAd (R2 = 0.22, p = 0.005), mean FAflow (R2 = 0. 19, p = 0.022) and mean AVd (R2 = 0.14, p = 0.034). Three pts (9.1%) showed significant VA stenosis by CDU and in, all cases, the location and degree of stenoses were confirmed by AG. The mean AVflow was lower in VA with significant stenosis (511.0 +/- 179.1 ml/min) compared to VA without stenosis (1,911.1 +/- 968.7 ml/min) (p = 0.006). The calculated values of VA blood flow rate obtained by the CDU technique (AV flow) were highly correlated with those determined by the AH method (QA) when considering all comparison values (n = 33, ICC = 0.74, p < 0.0001), for AV flow < 2,000 ml/min (n = 23, ICC = 0.82, p < 0.0001) and for AV flow < 1,500 ml/min (n = 14, ICC = 0.73, p = 0.001). No significant difference was found when QA (1,593.8 +/- 645.7 ml/min, range 559-2,778 ml/min) and AV flow were compared (p = 0.082). CONCLUSIONS 1) The CDU technique is a valuable and reproducible method for AV flow measurement and for early diagnosis of significant VA stenosis. 2) The AV flow is related to FA parameters. 3) Both methods, CDU and AH, correlated highly with each other when were applied on VA blood flow rate measurement.