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Background: We prospectively analyzed the effect of preexisting structural changes of the radial artery (RA) wall by histological examination on the wrist radiocephalic fistula (RCF) outcomes., Methods: During RCF creation, one segment of the RA wall was collected and its histomorphometric analysis was performed. The RCF function was evaluated by measuring blood flow rate., Results: At the end of follow-up, 75.7% of the thirty-seven patients enrolled were performing hemodialysis by using their successful RCF and 24.3% of them showed early RCF failure. Compared to patients with a healthy RA, the RCF of those with medial RA microcalcification reached up a lower flow and a shorter primary patency (P=0.005 and P=0.040, respectively). The RA microcalcification was predictive of the RCF function (coefficient -614.9, 95% CI: -994.7 to -235.1, P=0.003). Compared to patients with successful RCF, those with failed RCF had a greater frequency of weak RCF thrill after releasing the clamps (P=0.045). Dependence on hemodialysis during RCF placement was predictive of its early failure (OR: 23.2, 95% CI: 1.76 to 306.9, P=0.017). Both having at least one cardiovascular comorbidity (HR 4.30, 95% CI: 1.29 to 14.39, P=0.018) and a thicker media layer of the RA (HR 1.60, 95% CI: 1.87 to 2.15, P=0.002) were predictive of primary RCF patency., Conclusions: The function and survival of the successful RCF were related to preoperative RA abnormalities such as microcalcification and media layer thickness. Both dependence on hemodialysis during RCF placement and an attenuated RCF thrill were associated with early RCF failure.

Purpose: To report experience over five years of vascular access (VA) stenosis surveillance., Methods: We prospectively monitored the blood flow rate (QA) of 145 VA in 131 ESRD (age 62.6 ±13.5 y) patients (pts). QA measurement: within the first hour of the hemodialysis (HD) session by the Delta-H method using the Crit Line III Monitor. All VA with baseline QA < 700 mL/min or decreased > 20% from baseline over time met the positive evaluation (PE) criteria and were referred for angiography (AG) plus elective intervention if stenosis = 50%., Results: We found 54 cases of PE in 47 VA; the AG was performed in 87% (47/54) cases of PE and most of them (43/47, positive predictive value: 91.5%) showed significant stenosis (mean degree 80.5 ±12.9%). Mean QA increased from 554.7±107.6 mL/min to 977.9 ± 359.9 mL/min just before versus after preventive intervention (P<.001). Without difference when comparing the highest QA reported before stenosis development (889.8 ± 409.5 mL/min) and the QA recorded just post-intervention (P=.18). Kt/V index: improved from 1.43 ± 0.22 to 1.49 ± 0.21 just before versus after intervention (P=.006)., Conclusions: 1) The Delta-H technique is an accurate method for early diagnosis of VA stenosis and is useful in monitoring the hemodynamic effect of elective VA treatment. 2) After preventive intervention for stenosis, functional VA status is restored and HD delivery is improved.

Introduction: Periodic blood flow (QA) measurement is the preferred way for arteriovenous fistula (AVF) surveillance in chronic hemodialysis (HD) patients. Objectives. 1) Assess the efficacy of the temperature gradient method (TGM) on the QA determinations using the Twister™ device and to compare the functional results with the Delta-H method. 2) Evaluate the effect of blood pressure on the AVF function. Patients and method. We measured the QA non invasively in 30 AVF (24 radial and 6 brachial; mean duration 53.4 +/- 78.5 months) during HD in 30 stable patients (mean age 59.9 +/- 14.1 years, males 60 %, females 40 %; mean time on HD 37.4 +/- 40.6 months, diabetic nephropathy 20 %) by the TGM, described and validated by Wijnen et al (Kidney Int 2007;72:736). The QA was calculated from the temperature 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, with no need for a thermal bolus. The Twister™ device was used for reversing the blood lines without the need to disconnect them from the AVF lines nor to stop the blood pump. The QA was measured within the first hour of two consecutive HD sessions (the values were averaged). The mean arterial pressure MAP (diastolic pressure + 1/3 pulse pressure) was calculated simultaneous with the QA. In addition, the AVF blood flow was also determined during the same week in all patients by the Delta-H method using the Crit-Line III Monitor (ABF-mode, HemaMetrics, USA) during HD (manually switching lines)., Results: The mean QA was 1132.5 +/- 515.4 ml/min (range, 446-2233 ml/min). The mean coefficient of variation for duplicate QA measurements was 6.8 +/- 4.7 %; the MAP was not different when the reproducibility tests were performed (96.1 +/- 13.7 versus 96.6 +/- 12.8 mmHg, p = .72). No significant difference was found when comparing the mean QA between diabetic (n = 6, 966.4 +/- 340.7 ml/min) and nondiabetic (n = 24, 1174.4 +/- 548.3 ml/min) patients (p = .39). The mean QA was similar for patients with mean MAP < 100 mmHg (n = 18, 1101.0 +/- 552.7 ml/min) and for patients with mean MAP >&#95; 100 mmHg (n = 12, 1180.4 +/- 473.3 ml/min) (p = .69). No correlation was found between the mean QA and: age (r = 0.09, p = .62), time on HD (r = 0.06, p = .76), MAP (r = -0.21, p = .27), Kt/V index (r = 0.12, p = .51), distance between needles (r = - 0.17, p = .37) and AVF duration (r = -0.01, p = .96). The mean time required to measure QA with the TGM using the Twister™ device (5.9+/- 1.9 min) was significantly shorter compared with the Delta-H technique (26.8 +/- 1.9 min) or with the TGM (n = 35, 8.9 +/- 3.5 min, manually reversing lines) reported by Wijnen et al (Kidney Int 2007;72:736).) (for both comparisons, p < .001). The mean QA obtained by the TGM was not different when compared to mean ABF determined by the Delta-H method (1138.4 +/- 502.3 ml/min) (p=.83).The calculated values of AVF blood flow obtained by TGM were highly correlated with those determined by the Delta-H technique (r = 0.963, p < .001)., Conclusions: 1) The TGM is a valuable and reproducible indicator of QA during HD. 2) The Twister™ device is useful to reduce the time for QA measurement by the TGM. 3) The AVF blood flow values obtained by the TGM and the Delta-H technique correlated highly with each other. 4) It has been shown the lack of relationship between the AVF function and the patient's blood pressure.

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.

Purpose: To evaluate the functional effects of preventive vascular access (VA) intervention through periodic blood flow (Q A ) measurements during hemodialysis (HD) by the delta-H method., Methods: We prospectively monitored the blood flow rate (Q A ) 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. Q A was measured at least every 4 months by the delta-H method (Yarar (6)) using the Crit Line III Monitor (overall mean Q A 1247.6 +/- 519.7 ml/min). The mean arterial pressure (MAP) and Kt/V index were measured simultaneously with Q A . Thirty-eight VA (38%) met the positive evaluation criteria (absolute Q A <700 ml/min 50%, Q A 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 Q A increased from 563.8 +/- 115.4 ml/min just before intervention (Q A pre) to 975.7 +/- 351.8 ml/min just after intervention (Q A post) (mean delta Q A = 411.8 +/- 290.1 ml/min) (p < 0.001). We found a significant difference between the overall mean Q A 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 Q A before intervention (877.7 +/- 415.4 ml/min) and mean Q A 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 delta Q A 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 delta Q A and mean Q A post (r = 0.95, p < 0.001) or between mean delta Q A and overall mean Q A 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 Q A were 232.6 +/- 74.1 days and 2.8 +/- 0.6 ml/min/day, respectively. No significant correlation was found between mean delta Q A or Q A pre and mean restenosis period or decrease in Q A (p = ns)., Conclusions: 1) Monitoring Q A by the delta-H method is useful in assessing the hemodynamic response to elective VA intervention. 2) Mean Q A post was similar to the highest recorded mean Q A before intervention. 3) Mean delta Q A was related to mean Q A post and overall mean Q A after intervention. 4) The HD effectiveness (Kt/V index) improved after intervention.

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 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)., 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 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)., 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.

Background: Periodic intra-access blood flow rate (QA) monitoring is the preferred method for vascular access (VA) surveillance (NKF-K/DOQI, update 2000)., Objectives: 1) To determine the ultrafiltration (UF) method accuracy for early detection of VA stenosis. 2) To evaluate the hemodynamic effect of elective VA intervention (angioplasty or surgery). 3) To define the impact of periodic QA monitoring using the UF method combined by elective VA intervention on VA thrombosis., Patients and Methods: We prospectively monitored QA during hemodialysis (HD) in 65 ESRD (mean age 64.9 +/- 11.4 years, 20% diabetes) patients over 1 year period. All patients undergoing HD in the Hospital de Mollet by arteriovenous fistula (89.2%) or graft 10.8%. QA was measured at least every 4 months by the UF method using the Crit Line III Monitor. Fifty (77%) patients were included at the beginning of the study period and the remaining 15 (23%) were added later when they started HD. All patients with absolute QA <700 ml/min or decreased >20% from baseline met criteria of positive evaluation (PE) and were referred for angiography (AG) plus subsequent preventive intervention (angioplasty or surgery) if VA stenosis >50%. We also studied 94 not QA monitored patients since the beginning of the study period (mean age 64.6 +/- 13.7 years; 12.8% diabetes) that undergoing HD simultaneous in the Institut Nefrològic Granollers., Results: We performed 200 QA measurements in 509 months of follow-up. The overall mean QA was 1176.7 +/- 491.8 ml/min (range, 380.5-2904.0 ml/min). Three patients (4.6%) thrombosed VA. Nineteen (29.2%) patients had PE; none of them clotted VA. The AG was performed in 84.2% (16/19) patients with PE and all of them (16/16) showed VA stenosis > or =50%; 31.2% (5/16) were lost to follow-up (3 death, 2 transplantation); of the remaining explored patients (11/16), 72.7% (8/11) underwent intervention (3 angioplasty, 5 surgery). The mean QA increased from 577.2 +/- 108.2 ml/min to 878.1 +/- 264.4 ml/min postintervention (p=0.005). The positive predictive value, negative predictive value, sensitivity and specificity of UF method for VA stenosis were 84.2%, 93.5%, 84.2% and 93.5%, respectively. VA thrombosis rate in our 50 beginners QA monitored patients (mean age 64.5 +/- 1 1.4 years; 20% diabetes) was lower (2/50, 4%) compared to 94 not QA monitored patients (16/94, 17%) (p=0.024)., Conclusions: 1) QA monitoring using the UF method allows an early diagnosis of VA stenosis. 2) Serial QA measurement by UF method can be used in assessing the functional response to corrective VA intervention. 3) Periodic VA surveillance by QA measurements using the UF method combined with elective intervention results in reduced VA thrombosis.

A 70-year-old woman, who undergoing hemodialysis due to chronic pyelonephritis, is reported. She suffered from dyspnea due to pulmonary artery hypertension secondary to volume overload as a complication of high-flow brachial AVF. The combined estimation of vascular access blood flow rate (QA) and systolic pulmonary artery pressure by noninvasive methods (ultrafiltration and Doppler echocardiography, respectively) allowed us the diagnosis, make a surgical indication and post-surgical follow-up of AVF with hemodynamic repercussion.