Intraoperative Flow Measurements Ensure AV Access Function Access... · 2017-01-23 ·...

Vascular Access Surgery

Intraoperative Flow Measurements Ensure AV Access Function

• Quantifies Integrity of Flow

• Foreshadows AV Access Maturation

• Guides Revision Procedures

AMERICASTransonic Systems Inc.34 Dutch Mill RdIthaca, NY 14850U.S.A.Tel: +1 607-257-5300Fax: +1 [email protected]

EUROPETransonic Europe B.V.Business Park Stein 2056181 MB ElslooThe NetherlandsTel: +31 43-407-7200Fax: +31 [email protected]

ASIA/PACIFICTransonic Asia Inc.6F-3 No 5 Hangsiang RdDayuan, Taoyuan County33747 Taiwan, R.O.C.Tel: +886 3399-5806Fax: +886 [email protected]

JAPANTransonic Japan Inc.KS Bldg 201, 735-4 Kita-AkitsuTokorozawa Saitama359-0038 JapanTel: +81 04-2946-8541Fax: +81 [email protected]

www.transonic.com

Transonic Systems Inc. is a global manufacturer of innovative biomedical measurement equipment. Founded in 1983, Transonic sells “gold standard” transit-time ultrasound flowmeters and monitors for surgical, hemodialysis, pediatric critical care, perfusion, interventional radiology and research applications. In addition, Transonic provides pressure and pressure volume systems, laser Doppler flowmeters and telemetry systems.

Best Practice: Flow-assisted AV Access Creation and Revision

AV-AccessCoversheet(VA-100-fly)RevA 6-13

ResearchVascular Access Surgery

Transonic® intraoperative flow measurements provide on-the-spot or continuous measurements of volume flow for a functional assessment of an AV access. These measurements can foreshadow successful maturation of an AV fistula or graft, alert the surgeon to potential difficulties and guide the surgeon in achieving target flow values during an access revision.

SURGICAL ACCESS CREATIONAs surgeons construct more and more AV fistulas, their maturation is key to long-term hemodialysis. Measuring flow at the time of AV fistula construction assures the surgeon that hidden flow obstructions do not jeopardize early post-op patency. Moreover, studies demonstrate that quantitative flow data as fistulas are being surgically created can predict future maturation. Similarly, measuring flow during PTFE graft placements can help predict patency.

FLOW-BASED ACCESS REVISION SURGERYWhen an AV access needs to be surgically revised or a high flow fistula is banded, intraoperative flow measurements take the guesswork out of such revisions by providing the surgeon with quantitative data to reach the desired flow levels.

“Flow reduction using intraoperative access flow monitoring is an effective and durable technique allowing for the correction of distal ischemia and cardiac insufficiency in patients with a high-flow autogenous access.”

Lundell A, Begqvist D, Intraoperative Flow Measurements in Vascular Reconstruction, Annales Chirurgiae Gynaecologie 1992; 81(2): 187-191.

“Intraoperative measurements of access blood flow provide objective, reliable data that correlate to outcome. Routine use of this technology might lead to more efficient management of patients undergoing hemodialysis access surgery.”

Johnson CP et al, Surgery 1998; 124: 729-38.

“During banding of AVGs, it is very difficult to reduce access flow without causing a thrombosis. Therefore, one must measure flow to quantify the reduction.”

Presentation, “Banding (How I do it),” I Davidson, MD, CIDA, 2011.

TRANSIT-TIME ULTRASOUND TECHNOLOGY MEASURES VOLUME FLOW, NOT VELOCITY

Two transducers pass ultrasonic signals, alternately intersecting the vessel in upstream and downstream directions. The difference between the two transit times yields a measure of volume flow.

VascularAccessFlowprobes/Flowmeters(VA-101-ds) Rev A 8/13


AV Access: Vascular Flowprobes

Fig. 3: The OptiMax® family with J reflectors (shown) and L reflectors (not shown) are available in 4, 6, 8, 10 and 12 mm.

OptiMax® Flowprobes also offer two reflector shapes and five sizes to accommodate different surgical preferences and patient anatomies. The skin tabs secure the Flowprobe so that continuous hands free measurements can guide vascular constructions, banding or revisions. After the target flow is attained and the procedure is completed, the Probe can then be quickly removed. The L reflector Flowprobe design allows the Probe to be slipped on and off a carotid artery easily, facilitating quick pre- and post-procedure measurements.

Fig. 2: Anatomy of an OptiMax® Flowprobe.

Fig. 1: Handle Flowprobes: FMV-Series and FME-Series sizes from 1.5 mm to 14 mm. The FMV-Series simple J-style reflector defines the ultrasound flow sensing window, holds ultrasound couplant gel in place, and maintains the vessel in alignment with the Probe. A flexible neck allows positioning of the Probe head to conform to vessel orientation.

Skin Tab to stabilize Probe on vessel

Ultrasonic sensing window

Non-constrictive reflectors: J-style

L-style

Transonic’s Vascular Flowprobes measure volume flows intraoperatively in vessels from 1.5 mm to 14 mm to detect blood flow obstructions before leaving the operating room. This ability to correct otherwise undetectable flow restrictions provides the surgeon with a unique opportunity to improve the outcome for his or her patient.

OptiMax® Flowprobes

Skin tab

Flexible neck

Skin tab







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AV Access: Vascular Flowmeters

• Provides unsurpassed accuracy and resolution

• Ensures inflow, conduit and outflow patency

• Provides immediate, quantitative flow measurements

HT354 Single-channel Optima Flowmeter

Transonic’s new Optima Flow-QC® Flowmeter takes transit-time ultrasound flow measurement resolution to the highest level. The Optima’s unprecedented resolution accompanies lower offsets, and doubles the accuracy for low flows.

The Optima Flowmeter enables use of our Vascular Flowprobes for AV access surgery. Flowprobes are available in from 1.5 - 14 mm sizes. Their flexible neck permits optimal Probe positioning and easy measurement.

The AureFlo® system continuously measures, displays, records and documents absolute volume flow and other derived parameters. Shown here with the new HT353 single-channel Optima Flowmeter.

HT364 Dual-channel Optima Flowmeter permits simultaneous measurements with two Flowprobes.


Transit-Time Ultrasound Intraoperative Blood Flow Measurements during Arteriovenous Fistula Creation Protocol courtesy of Jose Zamora, M.D. San Diego, CA

Medical Note

FistulaCreationStealTestMedicalNote(VA-420-mn) Rev B 2013

A. FISTULA MATURATION TESTA1. Measure Venous Outflow* End-to-End or Venous End-to-Arterial Side Anastomosis: When the AVF is constructed with an end-to-end or venous-end-to-arterial-side anastomosis, simply measure venous outflow distal to the venous anastomosis (Fig. 2).

If the anastomosis is constructed with a venous-side-to-arterial-side anastomosis or end-artery-to-venous-side anastomosis, occlude the vein proximal to the venous anastomosis while measuring flow distal to the anastomosis (Fig. 3). If spasm occurs, papaverin can be locally infiltrated along the artery and vein while flow is continuously monitored.

Fig. 2: Measuring venous outflow flow in a fistula anastomosed end to side.

Fig. 3: Measuring venous outflow flow in a fistula anastomosed side to side.

IntroductionThis protocol for measuring intraoperative blood flow during AV fistula creation has two goals:1) To increase the probability of successful AV

fistula maturation with quantitative blood flow measurements.

2) To ensure that the newly created fistula is not immediately robbing the lower arm of flow and setting the stage for ischemic “steal” syndrome.

Measurement Steps (after AV Fistula Construction)1. Identify Vessel to Be Measured Identify and expose the AVF’s venous outflow. Identify

and expose the arterial conduit distal to the AVF anasto-mosis.

2. Select Flowprobe Sizes (FMV or FTV-Series) Measure the vein and artery’s diameters

with a gauge. Select a Probe so that the vein will fill between 75% - 100% of the ultrasonic sensing window of the Flowprobe (Fig. 1).

Probe Size NoNreStrictive veSSel raNge 3 mm 1.2 - 3.2 mm

4 mm 3.2 - 5.3 mm 6 mm 4.5 - 7.5 mm

3. Check Blood Pressure If systolic BP is greater than 100 mmHg, continue with

measurement. If systolic BP is less 100 mmHg, low AV fistula flow may be caused by low BP.1 Wait until BP increases to more than 100 mmHg.

4. Apply Flowprobe to Vessel1. Select a site wide enough to accommodate the Probe’s

acoustic reflector. 2. Apply sterile gel to the Flowprobe to ensure good

ultrasound coupling.3. Apply the Flowprobe to the vessel, bending the

Flowprobe’s flexible neck so that the entire vessel lies within the sensing window of the Probe and aligns at a 90º angle with the Flowprobe handle (Fig. 1).

4. Check the Signal Quality Indicator on the AureFlo® or Flowmeter display to verify good acoustic contact.

5. Listen to the pitch of FlowSound®. The higher the pitch, the greater the flow.

Fig. 1: Outflow vein filling 75- 100% of the Probe’s sensing window.

Venous Outflow

Intraoperative Blood Flow MeasurementsF l o w - A s s i s t e d F i s t u l a C r e a t i o n

B. “STEAL” TESTB1. Measure Fistula Arterial FlowMeasure brachial or radial arterial flow that supplies the fistula distal to the AV fistula anastomosis in order to detect imminent threat of ischemic “steal” syndrome (ISS) (Figs. 4-5).

B2. Evaluate Flow Values

Check that flow values are well above zero and that the direction of flow is running toward the hand (distally) and not reversed so that it is flowing (proximally) into the AV fistula. If in doubt, zero flow by occluding the artery immediately next to the Flowprobe (Fig. 5).

Fig. 5: Flow supplying the hand is measured with the Flowprobe placed on the artery distal to the AV anastomosis. Flow is zeroed by occluding the artery immediately adjacent to the Flowprobe.

No “Steal” IndicationIf the blood flow running distally to the hand is well above zero, there is no imminent threat of “steal”.

“Steal” IndicationIf blood flow running to the hand is close to zero and/or flow is reversed and moving up the arm toward the AV fistula, the fistula may be banded. Flow is then remeasured in the arterial segment of the artery distal to AV anastomosis (Fig. 5). This step is repeated until the surgeon is satisfied that there is sufficient flow running distal from the AV fistula anastomosis to the hand and the threat of “steal” is not imminent.*

DOCUMENT FLOWSAfter applying a Flowprobe to the artery or vein, wait ~ 10-15 seconds for mean readings to stabilize. When flow readings are stable, flow data can be captured by recording or taking a snapshot on the Aureflo®, or by pressing PRINT on a HT300-Series Flowmeter. If the HT300-Series flow reading is negative on the LED, press INVERT to reverse the polarity of the flow reading from negative to positive before printing out the waveform.

THRESHOLDS FROM THE LITERATUREThresholds (mL/min) to Predict AV Fistula Maturation:

Comparison of Studies

Table 1: In radiocephalic fistulas, initial flows of less than 170 mL/min correlated with failure within 90 days. In brachiocephalic fistulas, that threshold was 280 mL/min.1

Summary of Results of Johnson Fistula Creation Study1

AV-Fistulas Flow (mL/min)Failure within 90 days

(Requiring Intervention)p

value

Radiocephalic< 170 56 %

.001> 170 15 %

Brachiocephalic< 280 64 %

.01> 280 18 %

Table 3: Comparison of AV Fistulas threshold studies to predict maturation.

Thresholds (mL/min) Predict Fistula Maturation: Four Studies

AV FistulasBerman 20082

Johnson 19981

Won 20003 Lin 20084

Radio-cephalic > 140 (n = 21)

> 170 (n = 94)

> 160 (n = 50)

> 200 (n = 109)

Brachio-cephalic > 308 (n = 49)

> 280 (n = 128)

References:

1 Johnson CP et al, “Prognostic Value of Intraoperative Blood Flow Measurements in Vascular Access Surgery,” Surgery 1998; 124: 729-38.

2 Berman SS et al, “Predicting Arteriovenous Fistula Maturation with Intraoperative Blood Flow Measurements,” J Vasc Access. 2008; 9(4): 241-7.

3 Won T et al, “Effects of Intraoperative Blood Flow on the Early Patency of Radiocephalic Fistulas,” Ann Vasc Surg 2000; 14(5): 468-72.

4 Lin CH et al, “Correlation of Intraoperative Blood Flow Measurement with Autogenous Arteriovenous Fistula Outcome.” J Vasc Surg. 2008; 48(1): 167-72.

Table 2: AV Fistula guidelines as identified by Johnson study.1

Guidelines for Fistula Construction1

Flow Rate (mL/min) Recommendation

≤ 100 Abandon site

100 - 300At risk for early failure; observe closely; allow to mature > 4-6 weeks before using

> 300 Allow to mature 4-6 weeks before using

Fig. 4: Artery filling 75- 100% of the Probe’s sensing window.

* Eric S. Chemla, MD, Renal Transplant and Vascular Surgery, St. George’s Healthcare NHS Trust, London, UK.

Occlusion site

AV Anastomosis

PROTOCOL

Arteriovenous Fistula ConstructionF i s t u l a M a t u r a t i o n a n d S t e a l T e s t s

1. Create AVF; Identify & expose:a. AV fistula venous outflowb. Distal arterial flow

2. Measure Vein Diameter; Select Flowprobe sizes.

4a. Apply Flowprobe

A1a. Measure venous outflow distal to anastomosis

A2. Evaluate Flow per pre-established thresholdsRadiocephalic: >250-300 ml/minBrachiocephalic: > 400 ml/minBasilic vein transposition: > 500 ml/min

3. Check systolic BP ≥ 100 mmHg If < 100 mmHg, wait until BP ≥ mmHg

End-to-end or venous end-to-arterial side anastomosis.

A1b. Measure venous outflow distal to anastomosis while occluding vein proximal to anastomosis

A2a. Fistula likely to mature

A3. Examine anastomosis and site. Revise, if necessary

Flow does not meet pre-established threshold

A4. Remeasure and evaluate Flow per pre-established thresholds

B4. Repeat steps above until distal arterial flow indicates that steal is not imminent.


Apply papaverine & wait several minutes

Side-to-side or arterial end-to-venous side anastomosis

B1. Measure arterial flow distal to anastomosis while occluding vein proximal to anastomosis to detect imminent steal.

B2. Evaluate flow values. Check that flow runs distally and is > zero. (Clamp to zero, if in doubt.)

B2a. Steal not indicated.

B3. Steal possible; band fistula & remeasure distal arterial flow.

A5. Fistula maturity tenuous 1. Alert dialysis staff to suspect fistula

(Monitor fistulas with flows between 100-300 ml/min weekly).

2. Revise 2).3. Seek another fistula site 1).

Flow meets threshold




A. Fistula Maturation Test B. Steal Test

Brachial or radial artery distal to AV fistula anastomosis

1)

2)






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HT354 Single-channel Optima Flowmeter for measuring flow.


Equipment

OptiMax® -FTV Series Flowprobes Optimax® (Hand-free) Flowprobes enable extended flow measurements during surgery to guide intraoperative procedures. Specially-designed tape-on supports, affixed to a flexible neck, stabilize the Probe on the vessel during a procedure. The ultrasound sensing window is designed with a J reflector so that the Probe can be slipped around a vessel and remain in place.

OptiMax® Flowprobe

Probe body

Flexible neck

Vascular Flowprobes: FMV-Series Vascular Flowprobes feature a short handle and a J-style reflector designed for spot flow checks. The Probe’s flowsensing head consists of a simple J reflector that defines the ultrasound flow sensing window, holds ultrasound couplant gel in place, and maintains the vessel in alignment within the Probe lumen. A flexible neck allows positioning of the Probe head to conform to vessel orientation.

HandleReflector

Tape-on supports

Flexible neck

J-style Reflector

ProstheticGraftCreationMedicalNote(VA-414-mn) Rev D 2013


References1 Johnson CP et al, “Prognostic Value of Intraoperative Blood Flow

Measurements in Vascular Access Surgery,” Surgery 1998; 124: 729-38. 2 Berman SS et al, “Predicting Arteriovenous Fistula Maturation with

Intraoperative Blood Flow Measurements,” J Vasc Access. 2008; 9(4): 241-7.

INTRODUCTIONFlow cannot be measured directly on newly inserted prosthetic ePTFE grafts (Fig. 1) because air within the synthetic graft walls attenuates ultrasound signal transmission. Graft outflow is therefore measured on the outflow vein following completion of both the arterial and venous anastomoses (Figs. 2, 3). If the distal vein has not been ligated, flow is still measured proximal to the anastomosis, while the distal unligated section of the vein is temporarily occluded (Fig. 4).

MEASUREMENT STEPS:1. IDENTIFY VESSELS TO BE MEASURED Identify the exposed segments of the venous

outflow conduit for the graft. Determine the optimum site (wide enough to accommodate the Probe’s acoustic reflector) for applying the Probe, and clean the vein at this site from fat and excess tissue.

2. SELECT FLOWPROBE SIZES Estimate the diameter of the outflow vein with

a gauge. Select a Probe size so that the vein will fill between 75% - 100% of the lumen of the Probe. NomiNal Probe Size accePtable VeSSel raNge

4 mm 3.2 - 5.3 mm 6 mm 4.5 - 7.5 mm

3. APPLY FLOWPROBE Apply sterile Aquasonic® Gel 100 to the Flowprobe to provide

ultrasound coupling between the Probe body and Probe reflector. Apply the Flowprobe to the vein, proximal to the anastomosis, bend the Probe’s flexible neck segment as necessary, so that the entire vein lies within the lumen of the Probe and aligns with the Probe body (Fig. 5). Listen to the pitch of FlowSound® as the Flowprobe is applied to the vein. The higher the pitch, the greater the flow.

Check the Signal Quality Indicator (bucket display) on the Flowmeter ’s front panel or AureFlo’s green bars for ultrasound acoustic contact. An acoustic error message will be displayed if ultrasound contact falls below an acceptable minimum.

4. MEASURE AND EVALUATE VENOUS OUTFLOW With the Flowprobe positioned as under Step 3 (above), measure

venous average flow as displayed on the Flowmeter. An initial venous outflow < 400 mL/min is associated with a higher rate of initial graft failure.1 As the site recovers from surgery, flow will increase to levels preferred for hemodialysis (> 600 mL/min).

Fig. 3: Straight ePTFE Graft anastomosed to the side of an artery and end of a vein.

Ligated vein

Fig. 2: Loop ePTFE Graft anastomosed to the side of an artery and end of ligated vein.

Ligated vein

Fig. 4: In a graft anastomosed to an unligated vein, flow is measured while the distal portion of the vein is temporarily occluded.

Occluding unligated vein

Intraoperative Blood Flow Measurement during AV (Prosthetic) Graft Construction

Medical Note

Graft TypeFlow

(mL/min)Failure within 90 Days

(Requiring Intervention)p

value

PTFE Grafts< 400 65 %

.01> 400 40 %

Table 1: In prosthetic grafts, initial flows of less than 400 mL/min foreshadowed failure within 90 days.1

ePTFE-Grafts 1,2

Flow Rate Recommendation

≤ 250 mL/min Abandon site immediately

250 - 400 mL/minConsider prophylactic anti- coagulation

Fig. 1: Loop ePTFE graft from brachial artery to cephalic vein.

ePTFE Loop Graft

Fig. 5: Outflow vein filling 75- 100% of the Probe’s sensing window.

Venous Outflow

6. MEASURE POTENTIAL FOR STEAL SYNDROME (OPTIONAL)With the Flowprobe placed on the vein as previously, measure flow with, and without, occlusion of the artery distal to the arterial anastomosis. The difference between the two readings equals flow in the distal branch of the artery. When the flow reading without distal occlusion is higher than the reading with occlusion, blood in the distal branch is flowing retrograde to augment fistula flow and vascular steal may develop. (Note: Alternately, distal arterial flow can be measured directly by placing a Flowprobe on a properly cleaned arterial site distal to the anatomosis.)

1. Construct AV Graft: Identify & expose venous outflow.

2. Measure Outflow Vein Diameter;

Select Flowprobe size.

4a. Apply Flowprobe

5a. Measure venous outflow distal to anastomosis

6. Evaluate Flow per pre-established thresholds

Systolic BP > 100 mmHg

3. Measure Blood Pressure

4b. Wait until systolic BP > 100 mmHg

Systolic BP < 100 mmHg

End-to-end or venous end-to-arterial side anastomosis.

5a. Measure outflow distal to anasto-mosis while occluding vein proxi-mal to anastomosis

Side-to-side or arterial end-to-venous side anastomosis.

7a. AV Graft likely to be able to be used

Venous Outflow > 400 mL/min

7b. Examine anastomosis and site. Revise, if necessary


8. Remeasure and Evaluate Flow per pre-established thresholds

9. AV Prosthetic Graft use tenuous. Abandon, construct another graft.



5. DOCUMENT FLOWSAfter applying a Flowprobe to a vein, wait ~ 10-15 seconds. When flow readings are stable, flow data can be captured by recording or taking a snapshot on the AureFlo®, or by pressing PRINT on a HT300-Series Flowmeter. If the HT300-Series flow reading is negative on the LED, press INVERT to reverse the polarity of the flow reading from negative to positive before printing out the waveform.

PROTOCOL

Intraoperative Blood Flow Measurement during AV (Prosthetic) Graft Construction Cont.

www.transonic.com

BandingMedicalNote(VA-418-mn) RevG 2013


Flow-guided AV Fistula Banding Courtesy of M. R. Scheltinga, M.D., Máxima Medical Center, Veldhoven, The Netherlands.

Medical Note

Flow Measurement Steps0. Preoperative: From preoperative surveillance in the hemodialysis

clinic, determine % drop in flow to be achieved by banding.1. Identify & Expose Venous Outflow of Fistula: Make a second 1.5-cm

incision at least 10 cm downstream (of the upper arm cephalic or basilic vein) towards the axilla away from the dialysis can-nulation sites. Identify and expose the AVF venous outflow. Check if this part of the vein is suitable for measurements (no scar tissue/aneurysms/adhesions).

2. Select Flowprobe Size (FTV-Series): Measure the vein’s diameter. Select a Probe so that the vein will fill between 75% - 100% of the flowsensing window of the Probe (Fig. 1).

3. Measure Venous Outflow a) Confirm that the outflow site is wide enough to

accommodate the Flowprobe’s acoustic reflector. b) Apply sterile gel inside the Flowprobe’s sensing window to

ensure good ultrasound coupling.c) Apply the Flowprobe to the vein, bending the Probe’s

flexible neck so that the entire vein lies within the Probe’s

Why Band a High Flow Fistula?The need to increase venous outflow resistance in an arteriovenous fistula (AVF) used to deliver hemodialysis results from:

Hemodialysis Access-Induced Distal Ischemia (HAIDI)

Clinically significant HAIDI, that occurs primarily in diabetic patients, is a potentially devastating complication of an AVF. The surgeon’s challenge is to relieve the distal ischemia, but maintain a functional AVF for hemodialysis. One strategy is to band the AVF to increase AVF flow resistance, thereby reducing AVF flow and increasing distal flow.

Cardiac OverloadWhen AVF flow is too high (~>2L/min), cardiac function can become compromised resulting in cardiomegaly. Banding increases AVF resistance and lowers fistula flow, thereby reducing excessive stress on the heart.

Flow-Guided Fistula Banding The surgeon begins with a pre-operative AVF flow level (determined by a Transonic® Hemodialysis Monitor in the dialysis clinic) and pre-sets the percent decrease in AVF flow to be achieved by banding. As the band is tightened, AVF venous outflow is measured intraoperatively. These continuous measurements guide the surgeon in achieving a target AVF flow value.

sensing window (Fig. 1). d) Check the Signal Quality Indicator on the

AureFlo® or Flowmeter display to verify good acoustic contact.

e) Listen to the pitch of FlowSound®. The higher the pitch, the greater the flow.

4. Document Flows: When flow readings are stable, flow data can be captured by recording or taking a snapshot on the Aureflo®, or by pressing “PRINT” on a HT300-Series Flowmeter. If the flow reading is negative, press “INVERT” to reverse the polarity of the flow reading from negative to positive before printing out the waveform.

Fig. 1: Align the Probe on the vessel as shown.

Flow Measurement Protocol

0. Pre-operative: Determine % fistula flow decrease to be achieved by banding.

1. Expose AV fistula and its venous outflow (2 incisions).

2. Expose venous outflow diameter and select Flowprobe size.

3. Apply Flowprobe to venous outflow site.

4. Measure baseline flow. Calculate target flow (baseline flow times % decrease).

5. Tighten band. Remeasure flow.

6. Repeat step 5 until flow reaches intraoperative target flow.

Flow-guided AV Fistula Banding Cont.

Fig. 6: If HFA is also associated with HAIDI, measurement of finger pressures is also required. Once an optimal combination of access flow (> access thrombotic threshold level, generally > 500 mL/min) and finger pressure (>50 mmHg) is attained, the band is fixed.

Figs. 1,2: HAIDI: Banding of an AV fistula (AVF) may be indicated for hemodialysis access induced distal ischemia (HAIDI). Preoperative angiography of HAIDI patient with radiocephalic AVF shows the absence of hand arteries visualization (Fig. 1). Tissue necrosis in the hand (Fig. 2) also indicates presence of HAIDI.

Fig. 3: Banding: Minimally invasive positioning of a Transonic® Flowprobe guides the degree of tightening of a 5 mm Dacron band during this procedure.

Fig. 4: A 5 mm Dacron band is fixed using a clip and stitches. In this patient, AVF thrill was maintained and radial arterial pulses returned.

Fig. 5: Banding may also be performed for a high flow AV fistula (HFA) > 2L/min. This patient suffered from fatigue in the presence of a 3.7 L/min upper arm AVF.

Photo essay below shows continuous measurement of blood flow with a vascular flowprobe directing a fistula banding procedure, courtesy of M. R. Scheltinga, M.D., Dept. of Surgery, Máxima Medical Center, Veldhoven, The Netherlands.

Dacron Band

Sutures

Tissue necrosis, indicative of ischemic syndrome.

REFERENCESwww.vascularprocedures.com/html/algemeen/home.php

1. van Hoek F et al, “Steal in hemodialysis patients depends on type of vascular access,” Eur J Vasc Endovasc Surg 2006; 32: 710-717.

2. van Hoek F, Scheltinga MR et al, “Access flow, venous saturation and digital pressures in hemodi-alysis,” J Vasc Surg 2007;45: 968-73.

3. van Hoek F, Scheltinga MR et al, “Banding of hemodialysis access causing hand ischemia or cardiac overload,” Seminars in Dialysis 2009; 22: 204-208.

4. Scheltinga MR, van Hoek F, Bruyninckx CMA, “Surgical banding for refractory Hemodialysis Access-Induced Distal Ischemia (HAIDI),” J Vasc Acc 2009;10: 43-49.

5. Scheltinga MR, van Hoek F, Vascular Access. J. Tordoir (ed). “Banding for high flow hemodialysis access (HFA),” Minerva, Turin, 2009, pp 141-150.141-150.

FlowprobeBanding siteTape

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Vascular Access Management“A Circle of Care®”

Vascular Access

Proactive vascular access management depends upon a trio of Transonic® flow measurements that guide the surgeon, the nephrologist and the interventionalist throughout the natural history of a vascular access.

• Surgical creation of AV access: Transit-time ultrasound (intraoperative) flow measurements foretell successful maturation.

• During hemodialysis: Transonic® ultrasound dilution measurements provide ongoing surveillance and trending to detect development of hemodynamically significant stenoses.

• Intervention/Revision: When an access problem is identified, intragraft flow measurements guide the interventional radiologist during percutaneous transluminal angioplasty (PTA). Intraoperative flow measurements guide surgical revisions to resolve complications such as “steal” syndrome.

CircleofCareWhitePaper(VA-22-wp)RevB 2013

Vascular Access Management “A Circle of Care®” A V A c c e s s C r e a t i o n , S u r v e i l l a n c e

Access Creation: Intraoperative Blood Flow Measurements

The Centers for Medicare and Medicaid Services (CMS) Fistula First Break-through Initiative’s success has transformed the hemodialysis access in the United States from a “graft-oriented culture” to a “fistula-oriented culture.” Since 2012 more than 60% of American hemodialysis patients have AV fistulas.1 Yet, the number of fistulas that do not mature (estimated to be between 28-50%)2 continues to confound and challenge the hemodialysis care provider.

In his landmark 1998 study in Surgery, Johnson et al reported that for an AV fistula to mature, a venous outflow equal or greater than 100 mL/min at its creation is advised. For an AV prosthetic graft, an initial venous outflow of less than 250 mL/min is associated with a higher rate of initial graft failure.3 As the access matures and arterializes, flow generally increases to levels needed for hemodialysis (greater than 500 mL/min). To ensure adequate flow for hemodialysis, Transonic® intraoperative blood flow measurements provide the surgeon with quantitative flow values during creation of the access (Fig. 1). Johnson and others report that intraoperative blood flow rates at access creation directly correlate to access outcomes including: patency, number of interventions, and length of hospital stays.

Fig. 1: Measuring arteriovenous (AV) fistula venous outflow with Transonic® Perivascular Flowprobe.

“Adequate blood flow in peripheral hemodialysis fistulae and

grafts is vital to the success of hemodialysis and to the survival of the

patient. Reduction in flow . . . presages failure of the access device

itself. Access flow can therefore be considered a fundamental property

of the access that should be monitored.” Depner, TA et al,

Vascular Access Management “A Circle of Care®”

Fig. 2: Trending of vascular access flow over a one year time frame with PTA interventions noted by arrows.

Hemodialysis: Surveillance

The Kidney Disease Outcomes Quality Initiative (KDOQI) Clinical Practice Guidelines for Vascular Access and the National Kidney Foundation codified Dr. Depner’s advocacy of access flow monitoring by stating “prospective surveillance of AV grafts and fistulas for hemodynamically significant stenosis, when combined with correction, improves patency and decreases the incidence of thrombosis.”

5 Canadian, Australian and European Guidelines also call for surveillance during hemodialysis to forestall stenosis formation and prolong the life of the access. Intra-access measurements (ultrasound dilution technology) are cited as the preferred method for surveillance.

Transonic’s ultrasound dilution technology is recognized as the “gold standard’ intra-access flow measurement technology for hemodialysis patient surveillance.6 The method uses Transonic Flow-QC® Hemodialysis Monitors and Flow/dilution Sensors to directly measure dialysis adequacy (delivered blood flow, recirculation) for on-the-spot correction of problems during hemodialysis and to trend vascular access flow to detect flow limiting problems wherever they occur in a vascular access (Fig. 2). Cardiac output and associated parameters can also be measured with this tecnology during the dialysis treatment.

I n t e r v e n t i o n a n d R e v i s i o n





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Vascular Access

REFERENCES1 http://www.fistulafirst.org/2 Asif A et al, “Early Arteriovenous Fistula Failure: A Logical

Proposal for When and How to Intervene,” Clin J Am Soc Nephrol 2006; 1: 332–339.

3 Johnson CP et al, “Prognostic Value of Intraoperative Blood Flow Measurements in Vascular Access Surgery,” Surgery 1998; 124: 729-38.

4 Saucy F et al, “Is intra-operative blood flow predictive for early failure of radiocephalic arteriovenous fistula?” Nephrol Dial Transplant 2010; 25: 862–867.

5 K/DOQI Clinical Practice Guidelines for Vascular Access. Update 2000 Guideline 21: Treatment of Thrombosis and Associated Stenosis in Dialysis AV Grafts and Primary AV Fistulae. Am J Kidney Dis 37(suppl 1): S164, 2001.

6 Does Vascular Access Surveillance Improve Access Patency? Myth & Reality: A Report of The Scientific Literature, Transonic Systems Inc. DL-52, 2004.

7 Vesely TM et al, “Use of a Catheter-based System to Measure Blood Flow in Hemodialysis Grafts during Angioplasty Procedures,” J Vasc Intervention Rad 2002; 13(4): 371-378.

ConclusionIn the outcomes-driven climate of proactive end-stage renal disease (ESRD) care, Transonic® quantitative flow

measurements are integral to successful and comprehensive vascular access management. During creation

of the access, during hemodialysis and/or during interventions or revisions, respective Transonic® flow

measurements inform and guide the surgeon, nephrologist and/or interventionalist as they seek to create

and maintain a healthy access for their patients. Transonic® flow-based “Circle of Care” is a cornerstone for

proactive Vascular Access Management.

Vascular Access RevisionIntra-graft Flow Measurements During angioplasty, a Transonic® ReoCath® Flow Catheter and

Endovascular Flowmeter provide the interventionalist with

immediate flow feedback (Fig. 3)7 for quantitative confirmation

that a hemodynamically significant stenosis has been corrected

or that elastic recoil has not compromised the flow correction.

Intraoperative Flow MeasurementsWhen surgery is the access revision option, intraoperative flow measurements inform during the revision.

Transonic® quantitative measurements replace guesswork especially when an access needs to be banded to

mitigate ischemic steal syndrome.

Fig. 3: ReoCath® Flow Catheter measuring intragraft flow post-angioplasty.

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