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Adv. Vas. Son.
Test 2 Hemodialysys Fistulas and Grafts
| Question | Answer |
|---|---|
| Graft and Fistula facts: | Created to sustain PTs W/ end-stage renal failure |
| What does hemodialysis do? | Removes waste products from blood |
| How many Pts in the USA are dialysis dependent and that number continues to increase? | 300,000-400,000 |
| Want to create a fistula where? | As far distally as possible in nondominant arm, Preserves Prox vessels for potential future access |
| Why are upper extremities preferred with fistulas? | Lower infection rate and easier access |
| What are signs of possible access failure? | Pre-op assessment for vein/artery suitability, Difficult cannulation or thrombus aspiration, Elevated venous pressure during dialysis, Poor dialysis |
| More signs of possible access failure? | Unexplained area reduction ratio <60%, Shunt collapse, Distal limb ischemia, Abcene of fistula palpable "thrill", Per-graft fluids or mass |
| Where is a central venous catheter places of access? | IJV or subclavian vein insertion, Temporary- short term solution |
| Where is an Arteriovenous Fistula (AVF)? | Usually in non-dominate arm |
| What is a Brescia-Cimino Fistula? | Rad A to Ceph V (most common), Autogenous, Known for long term patency, Low complication rate, Ulnar A to Basilic V may also be created but uncommon |
| AVF has to do what before it can be used? | Mature- or adequate flow volume may not occur |
| How long should Fistula Maturity take? | 8-12 weeks |
| What does a fistula look like once it has become mature? | Sausage like from increased pressure |
| Why is TD contact sometimes difficult? | Superficial location (lots gel and little pressure |
| What are other fistula sites? | Brach A to Ceph V. Brach A to Basilic V, Brach A to Brach V |
| Approx how many PTs are not candidates for AVF? | 50% |
| Grafts are favored in the USA but there is a strong trend towards? | Fistula creation |
| The Polyurethane, Vectra graft (Thoralon)facts: | Can be used immediately, no maturation time, Self-sealing, IMPENETRABLE BY ULTRASOUND |
| If an Access graft is straight then it courses which way? | From Distal A to more Prox superficial V |
| What is good about the Forearm Loop Graft? | Provides more length and more puncture locations for dialysis |
| Other access graft locations? | Brach A to Basilic V, Subclacian A to Jugular V, Superficial fem A to GSV |
| Grafts have shorter what than fistulas? | Shorter patency rates |
| Abroad about 80% of hemodialysis PTs have native fistulas, whole 20% have grafts. The % are ______ in the US? | Reversed, but there is a strong trend towards increasing the number of fistulas |
| What is the % of Early failures with No Mapping, and Mapping? | No Mapping= 36%, and Mapping =8% |
| What is the % of 1-Yr Patency with No Mapping and Mapping? | No Mapping= 48%, and Mapping= 83% |
| What should you look for post-op? | Graft thrombosis/stenosis, Flow volume, Arterial steal, Venous outflow, Peri-graft mass |
| What is the suitable radial arterial diameter? | ≥2.0 mm |
| What is the suitable PSV? | ≥ 50 cm/s |
| What is the required venous luminal diameter (W/ or W/out arm tourniquet)? | ≥2.5 mm for Fistula. ≥4.0 mm for Graft |
| Why are brachial veins rarely used for hemodialysis access? | They are TINY |
| What are Graft/Fistula complications? | Thrombosis/Occlusion, Stenosis, Arterial Steal(digit ischemia), Distal venous HTN, Aneurysms/Pseudoaneurysms, Elevated right sided heart pressure due to excessive graft flow, Infection(mostly synthetic grafts) |
| Where do you measure stenosis? | @ Prox and Distal anastomosis, W/in graft, and in venous outflow tract- due to initmal hyperplasia or thrombus |
| Hoe long do grafts and fistulas mature for | 4-6 weeks |
| Grafts (PTFE) are the most common? | Procedure |
| NO BLOOD PRESSURE where? | OVER A GRAFT |
| In a Fistula/Graft flow should be high/low resistance, (high/low diastolic flow) | LOW resistance, HIGH diastolic flow |
| If there is retrograde arterial flow what does that mean? | Steal |
| Flow may be higher resistance Distal/Proximal? | Distal |
| Where do you measure and record PSV & EDV? | Prox, Mid, & Distal, @ any region of suspected stenosis, and @ anastomotic sites |
| What should Doppler waveforms demonstrate just proximal to the graft or fistula? | Low resistance (High diastolic flow) |
| High resistance in the brachial or radialartery flow prox to a graft of AVF is a sign of? | Graft/Fistula occlusion or severe stenosis |
| Vein stenosis is more likely to occur where? | In a a graft than a fistula |
| When is it common to have flow reversal back down into the limb? | Under high arterial pressure |
| Increased venous pressure in itself may cause what type of symptoms? | Edema in the hand |
| What are the Flow Volume (ml/min) calcs? | Q=Area x TAV x 60 sec Q=Areax Avg Max Vel x 60 sec |
| What is TAV? | Average velocity over time, so mean systolic velocity, mean diastolic velocity and mean velocity through a cardiac cycle are calculated |
| Assess Per-graft/fistula tissue for: | Hematomas, & Pseudoaneurysms |
| Pseudoaneurysms are common and result from? | Dialysis puncture |
| If Pseudoaneurysm is < 5mm they? | Remain stable |
| If pseudoaneurysm > 5mm they? | Should be carefully followed or surgically repaired |
| Steal facts: | May be ASX or cause digit ischemia, If SX get PVR or PPG WFs from ipsilateral digits, Obtain pressure from the most symptomatic digit |
| Digit pressures <69 mmHg are associated with what? | Ischemia |
| Infection Etiology: | Operative contamination Puncture, Wound infection, Appears as peri-graft fluid collection, Can resemble a seroma, Confirmation usually requires analysis of aspirated fluid |
| What is a seroma? | Serous fluid collection adjacent to graft, Appear as peri-graft fluid collection, result from serum filtering thorough the graft wall, Usually benign condition as long as there is no extrinsic compression on the graft |
| Other complications: | Venous HTN, Outflow stenosis, Arterial flow decrease |
| What do NORMAL grafts and fistulas have? | Very HIGH systolic and diastolic velocities, Flow is v "low-res", continuous forward, High vel flow |
| What is the PSV in Normal grafts and fistulas? | PSV between 150 and 300 cm/s |
| What is the EDV in Normal grafts and fistulas? | EDV between 60 and 300 cm/s |
| Inflow artery should have LOW res flow with increased? | Increased PSV (30 - 100 cm/s) |
| Normal Volume Flow? | >800 mL/min |
| Dialysis Graft Stenosis: >50% diameter stenosis what is the peak systole? what is the velocity ratio? | Peak Systole >400 cm/s, Velocity Ratio 2:1 or 3:1 (some reports) |
| Criteria for > 50% Fistula Stenosis: Radial artery to Cephalic vein (end to side): facts: | PSV> 400 cm/s, Ratio 2:1 or 3:1 (Anastomotic stenosis PSV/ Radial Artery PSV) |
| For outflow cephalic vein stenosis what is the ratio? | ≥ 3:1 |
| Graft flow Volumes (mL/min) for access grafts: | <350- poor dialysis, pending graft failure. <5000 increased risk of failure >800- normal flow >1500- possible CHF |
| Fistula Flow Volumes (ml/min): | Fistulas can survive at lower flow volumes <300 poor dialysis 300-500 borderline >500 (w/ 4 mm outflow vein) acceptable >800= NORMAL |
| Where do you obtain flow volume? | From feeding artery (brachial, radial, or ulnar) |
Created by:
EmilyGriffin
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