PROSPECTIVE MONITORING OF BLOOD FLOW (Qa) BY ULTRASOUND DILUTION TECHNIQUE (UDT) IN PREVENTING HEMODIALYSIS (HD) GRAFT THROMBOSIS (GT)

Pulmonary capillary blood flow (Qc) in the exercising subject was calculated from the rate of disappearance of N2O during steady state breathing of an N2O-He-O2 mixture. Measurements were made after alveolar rinsing (reciprocal of N2 washout) had occurred, and up to 30 sec, a time period accompanied by minimal recirculation, since FaNN2O during this period did not rise significantly. Repeatability of the method, judged as the difference of a second estimate from a first on the same subject, was comparable to that reported for the direct Fick technique in resting subjects (31 of 33 paired observations agreed within 20%). Results over a wide range agreed with almost simultaneous measurements by a dye dilution technique (24 of 26 paired observations agreed within 20%), and when related to pulse rate and to Vo2, were comparable to those of the other workers whose subjects were studied in a similar posture. Indeed, this technique (using the indirect Fick principle under “steady state” conditions) probably attains its greatest accuracy during exercise when other methods become less easily applicable. Submitted on December 18, 1961

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Predicting arterio-venous fistula failure by urea–method derived access blood flow in chronic hemodialysis patients

The Journal of Vascular Access ◽

10.1177/1129729820920115 ◽

2020 ◽

Vol 21 (6) ◽

pp. 1011-1016

Author(s):

Kumtorn Lelamali ◽

Piyarek Papirachanat ◽

Thitiya Puavilai

Keyword(s):

Blood Flow ◽

Characteristic Curve ◽

Hemodialysis Patients ◽

Chronic Hemodialysis ◽

Interquartile Range ◽

Dialysis Access ◽

Ultrasound Dilution ◽

Limb Edema ◽

Venous Fistula ◽

Urea Method

Background: Dialysis access is an essential part of hemodialysis. Determining the access blood flow (Qa) can help predict arterio-venous fistula thrombosis. Qa determination by the urea method, which was previously described in the past is simple and is available in most of the dialysis units but was not be able to predict arterio-venous fistula thrombosis. Aim: To compare the efficacy of Qa determination by the urea method and by ultrasound dilution methods in predicting arterio-venous fistula failure. Methods: Qa was measured by urea method and by ultrasound dilution simultaneously, every 3 months for a period of 1 year, in stable chronic hemodialysis patients with arterio-venous fistula. Arterio-venous fistula failure determined by clinical parameters and confirmed by Doppler ultrasound before sending the patient for interventional angioplasty. Results: This study enrolled a total of 16 patients, with 63% being male, 75% with lower-arm arterio-venous fistula and around 43% with previously done angioplasty. 59-Qa measurements were done, and 6 patients underwent angioplasty (one patient for severe upper limb edema, one for access thrombosis, and four for access dysfunction). Qa determination by the urea method had non-significantly lower Qa, (745 mL/min (interquartile range: 509–1143) and 779 mL/min (interquartile range: 530–1160), (p = 0.58)) and high correlation (r = 0.83, p < 0.001) to Qa by ultrasound dilution. The cut-off criteria with its sensitivity and specificity in predicting the access failure were 440 mL/min, 66.67%, and 96.15% for Qa determination by the urea and 400 mL/min, 66.67% and 90.38% for Qa by ultrasound dilution, respectively, with no difference in the area under the receiver operating characteristic curve. Conclusion: Measurement of Qa determination by the urea method is well correlated with Qa by ultrasound dilution and can be used to predict vascular access failure.

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Native Arterio-Venous Fistula for Hemodialysis: What to Expect Early after Creation?

The Journal of Vascular Access ◽

10.1177/112972980300400202 ◽

2003 ◽

Vol 4 (2) ◽

pp. 39-44 ◽

Cited By ~ 7

Author(s):

M. Leblanc ◽

E. Saint-Sauveur ◽

V. Pichette

Keyword(s):

Blood Flow ◽

Vascular Access ◽

Complication Rates ◽

Ultrasound Dilution ◽

Flow Monitoring ◽

Significant Difference ◽

Lower Complication ◽

Vascular Mapping ◽

Venous Fistula

Native arterio-venous fistulas (AVFs) are preferred for hemodialysis vascular access over synthetic grafts and long-term catheters. However, prevalence rates of native AVFs are variable around the world and have increased only slightly in United States since the DOQI guidelines. To increase rates of native AVFs, pre-operative vascular mapping by ultrasound has been found of major help for appropriate selection of the vessels. The minimal desirable lumen diameter of the artery should be > 2 mm and > 2.5 to 3 mm for the vein at the anatomosis. Early failure can be reduced to less than 10% when the feeding artery is > 2 mm, even in diabetics. If sizes of the vessels are smaller than those targets at the wrist, moving to the upper arm should be considered. The interval between creation and first cannulation varies from 2 weeks to 4 months. There might not be much advantage to wait for more than 4 weeks; however, in large dialysis units, observing a delay of 4 to 6 weeks may be worthwhile to avoid initial problems such as infiltrations and lacerations. Access flow monitoring is essential since it is a reliable predictor of vascular access dysfunction, reducing associated morbidity and costs. Early monitoring of recently created native AVFs has shown that the increase in intra-access blood flow occurs very soon after construction and becomes maximal after a few weeks. A recent prospective study involving all new native AVFs monitored by ultrasound-dilution between weeks 6 and 10 after creation, and every 3 to 6 weeks over 4 months, showed no statistically significant difference in access blood flow between the initial and final measurements (respective values of 1132 ± 681 and 1097 ± 644 ml/min). Access flow was higher in males, and in brachio-cephalic compared to radio-cephalic AVFs. Over the long-term, AVFs are associated with longer patency and lower complication rates, and efforts should be directed at further increasing their prevalence.

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VALIDATION IN SHEEP OF THE ULTRASOUND DILUTION TECHNIQUE FOR HEMODIALYSIS GRAFT FLOW

ASAIO Journal ◽

10.1097/00002480-199603000-00303 ◽

1996 ◽

Vol 42 (2) ◽

pp. 81

Author(s):

A. Dobson ◽

H. J. Harvey ◽

R. D. Gleed

Keyword(s):

Dilution Technique ◽

Ultrasound Dilution ◽

Graft Flow ◽

Hemodialysis Graft

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Arterial hematocrit and separation of cells and plasma in the dog kidney

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1964.207.1.128 ◽

1964 ◽

Vol 207 (1) ◽

pp. 128-132 ◽

Cited By ~ 19

Author(s):

Francis P. Chinard ◽

Theodore Enns ◽

Mary F. Nolan

Keyword(s):

Blood Flow ◽

Volume Of Distribution ◽

Human Albumin ◽

Indicator Dilution ◽

Regression Equations ◽

Dilution Technique ◽

Transit Times ◽

Dog Kidney ◽

The Mean ◽

The Difference

With the indicator-dilution technique, the mean transit times of cells (tr) labeled with Cr51 and of plasma (tpl) labeled with T-1824 or as human albumin-I131 decrease as the arterial hematocrit (Hct) decreases. The regression equations are: tr = 0.0388 Hct + 1.73 and tpl = 0.0596 Hct + 1.69. The separation of cells and plasma labels, as measured by the difference of the mean transit times (Δt), is also related to the hematocrit. Δt = 0.00895 Hct + 0.269. There is an excess plasma label volume of distribution per 100 g kidney, ΔVpl, which may be intra- or extravascular. ΔVpl = QrΔt (1 - Hct), where Qr is blood flow per 100 g kidney. ΔVpl is independent of tr and of Hct. However, ΔVpl increases with Qr. ΔVpl = 0.127 Qr + 1.79. The hypothesis that the separation of cells and plasma results from transcapillary passage of the plasma labels is consistent with but is not established by the data.

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How to carry out monthly blood flow surveillance of fistula in large-scale hemodialysis units: A cross-sectional study

The Journal of Vascular Access ◽

10.1177/1129729820923939 ◽

2020 ◽

pp. 112972982092393

Author(s):

Ya-wen Mo ◽

Chun-yan Sun ◽

Li Song ◽

Li-fang Zhou ◽

Ting-ting Zhuang ◽

...

Keyword(s):

Blood Flow ◽

Arteriovenous Fistula ◽

Doppler Ultrasound ◽

Radial Artery ◽

Brachial Artery ◽

Dilution Technique ◽

Cross Sectional ◽

Duplex Doppler Ultrasound ◽

Duplex Doppler ◽

Artery Flow

Background: The important effect of regular blood flow surveillance on arteriovenous fistula maintenance is emphasized. The ultrasonic dilution technique for blood flow surveillance can be performed during hemodialysis, but there are some limitations. Blood flow is traditionally measured by duplex Doppler ultrasound during the nondialysis period. However, the surveillance workload for arteriovenous fistula has increased with the rapid increase in the hemodialysis population size. Efficient methods for blood flow surveillance during hemodialysis are needed. Methods: Eighty-four hemodialysis patients with a forearm radiocephalic arteriovenous fistula were enrolled in this cross-sectional study. Each received blood flow measurements using ultrasonic dilution technique and duplex Doppler ultrasound during hemodialysis. Duplex Doppler ultrasound measurements included the blood flow of the brachial artery and radial artery. The correlations between these variables were analyzed. Results: The correlation coefficients ( r) between flow measured by ultrasonic dilution technique and brachial artery flow measured by duplex Doppler ultrasound, between flow measured by ultrasonic dilution technique and radial artery flow measured by duplex Doppler ultrasound, and between brachial artery flow and radial artery flow measured by duplex Doppler ultrasound were 0.724, 0.784, and 0.749, respectively (all p < 0.001). Conclusion: Blood flow measured by ultrasonic dilution technique was positively correlated with blood flow measured by duplex Doppler ultrasound during hemodialysis, suggesting that duplex Doppler ultrasound can be used to monitor the trends in the blood flow of the brachial artery and radial artery for timely intervention to improve patency during hemodialysis.

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