Why do we need Dedicated Subspecialists and Interventionalists?

Transcription

1 Optimal Hemodialysis Access Management and The Role of the Interventionalist Vascular Access Education Day May 2, 2009 Interior Health Authority Peter C. Gregory, MD Medical Director Vascular Access Center of Seattle Objectives Understand The importance of vascular access The types of vascular access The tools to treat access dysfunction To enhance your ability to detect and act on the at risk vascular access utilizing hands on physical examination Real time problems during hemodialysis K-DOQI guidelines Recognize the crucial concept of Fistula Maturation Recognize the importance of a team approach to HD vascular access What is Interventional Nephrology? Dedicated Nephrology Subspeciality that involves Interventional Procedures for patients with Renal Disease. Hemodialysis Vascular Access (AVGs & AVFs) Angiography Angioplasty Thrombectomy Stent placement Fistula Maturation (Obliteration of accessory veins, etc.) Dialysis Catheter Placement Temporary and Tunneled Catheters Subcutaneous Port Placement Peritoneal Catheter Placement Renal Ultrasonography Renal Biopsies Why do we need Dedicated Subspecialists and Interventionalists? Yesterday's Attitudes Dialysis patient assigned to low priority in treatment facilities No organized strategy with regards to vascular access Too many grafts and catheters Fix what is broken when it breaks attitude Lack of nephrology involvement Course of least resistance Cause of Hospitalizations in New ESRD HD Patients HD Access First 3 Months After 3 Months Cardiac GI Non- Others Access Infections Adapted from Arora et al., JASN 2000; 11:740 1

2 Relative Mortality Risk Native AVFs are superior Fistula Use Europe vs. U.S. No DM, PVD, CAD DM, PVD, and/or CAD Cath AVG Cardiac Infection AVF *Dhingra, KI (60), 2001 KI 02; 61(1) TODAY s Prevalent Use of AVF by ESRD Network NKF K-DOQI Practice Guidelines evidence-based clinical practice guidelines for all stages of chronic kidney disease and related complications Established 1997 Updated in 2000, again in sets of guidelines adequacy, anemia, nutrition, Vascular Access Work Group established Introduced 38 access specific guidelines (2000) Narrowed to 8 evidence based guidelines and 8 clinical practice recommendations (2006) As of January 2006, the prevalent rate has achieved the goal of >40% (Source: NVAII) K-DOQI Practice Guidelines Vascular Access Workgroup Concluded that quality of life and overall outcomes for hemodialysis patients could be improved by achieving two goals Increasing placement of native AV fistulae This led to the formation of Fistula First Initiative Detecting access dysfunction prior to access thrombosis Management of vascular access complications relies on a multidisciplinary approach...the goal of these management efforts is the preservation of vascular access NKF-K/DOQI guidelines 2000 Management of Complications: Guidelines

3 Solutions to the problem Dedicated caregivers Nurses, techs, doctors, social workers, nutritionists,.. Emphasis on fistula placement However new problems and issues have arisen NATIVE ARTERIOVENOUS FISTULAE (AVF) Native Arteriovenous Fistula The AVF is the preferred vascular access Best long-term primary patency Requires the fewest interventions and has the fewest complications Prevalent patients should have a 66% AVF rate* (2000 goal was 50%) Target date 2009 per Fistula First Location of the AVF The wrist: It is simple to create. It preserves more proximal vessels for future access placement. It has few complications. (incidence of vascular steal, thrombosis, and infection is low) More prone to failure due to lower blood flow rate *K/DOQI Guideline 8 Location of the AVF (cont) Location of the AVF (cont) The elbow (brachialcephalic) It has a higher blood flow compared to the wrist fistula. The cephalic vein in the upper arm is easy to cannulate and is easily covered, providing a potential cosmetic benefit Transposed brachialbasilic fistula The transposition procedure may create significant arm swelling and pain Higher incidence of steal and arm swelling than other fistula types Prone to swing site stenosis 3

4 Typical surgical scar of a transposed Brachiobasilic fistula *photo from Janet Holland Physical Assessment: AV Fistulae Inspection general development skin condition? pseudoaneurysms Palpation thrill or pulsation pressure change to venous outflow compression Auscultation quality and amplitude of bruit Other Indicators of Access Dysfunction Fistula Maturation Change in venous/arterial pressures Decreased blood flow Recirculation Swollen extremity Decreased Kt/V Prolonged bleeding Aneurysm formation Pulling clots Difficult cannulation Non maturing AVF Process by which a fistula becomes suitable for cannulation (ie, develops adequate flow, wall thickness, and diameter) Rule of 6 s: In general, a mature fistula should: Be a minimum of 6 mm in diameter with discernible margins when a tourniquet is in place Be less than 6 mm deep Have a blood flow greater than 600 ml/min Be evaluated for nonmaturation 4 6 weeks after surgical creation if it does not meet the above criteria National Kidney Foundation. Am J Kidney Dis. 2006;48(suppl 1):S1-S322. How do you examine the maturing fistula? Look, listen, and feel Tourniquet application Gentle Place high in axilla Wait until surgical scar heals What to do with findings? Document Be proactive: inform your surgeons and nephrologists Realize that you are probably CORRECT Experienced dialysis nurses have an 80% success rate for identifying fistula maturity* What should you find with a good fistula? Diameter 6 mm (remember the rule of 6 s) Vessel walls firm to the touch No prominent collateral veins Continuous low-pitched bruit Strong bruit/thrill at arterial anastomosis *Robbin ML, et al. Radiology. 2002;225:

5 Look for Complications Early Fistula Failure Changes in Access Redness Drainage Infection Abscess Cannulation sites Aneurysms Changes in Access Extremity Skin color Edema Small blue or purple veins Hematoma Bruising Central or outflow vein stenosis Distal Areas of Access Extremity Hands/Feet: Cold Painful Steal Numb syndrome Fingers/Toes: Discolored Juxta-Anastomotic Stenosis Usual treatment is PTA Venous Hypertension may develop Accessory Veins Down stream (toward central veins) Dorsum of hand/forearm Treat with ligation or coil placement *slide courtesy of Fistula First Juxta-Anastamotic (JA) Stenosis Affects vein segment adjacent to anastomosis (< 4 cm from anast.) Develops after creation Clamp injury/mobilization Skeletonization of vein Sheer stress injury/bf 10-20X Very common cause of early failure Easily diagnosed by physical exam Results in poor inflow Fistula fails to develop Typical Location of Stenosis Grafts (n=156) versus Fistula (n=283) Juxta-Anastomotic Stenosis: Physical Exam 1. Palpate the arterial anastomosis Strong pulse Palpable defect Weak or absent thrill JA Stenosis = Inflow stenosis.not just a problem of immature fistulae Arterial needle sucking up Excessively negative arterial pressures Unable to maintain appropriate pump speed Poor clearance Poor thrill/collapsed fistula 3. Thrill may be louder here than at the anastomosis 2. Move finger upward along fistula Pulse disappears or weakens Decrease caliber/pressure of vein 5

6 Inflow Stenosis Juxta-Anastomotic Stenosis Angioplasty Treatment AVF Fistulagram: Poor flow due to JA stenosis Fistulagram post angioplasty: Improved caliber and flow Venous Hypertension of Hand Venous Hypertension/JA Stenosis Distended superficial veins on the dorsum of the hand Physical examination - Large vein(s) on back of hand - May be pulsatile Side to side anastomosis Hand swollen and painful 6

7 Accessory Veins: Physical Exam 1. Occlude fistula at point A while palpating anastomosis - Thrill will disappear Native Radio-Cephalic AVF Multiple Accessory Veins 2. Move up the fistula using the same maneuver. When you reach point B, the thrill will return Accessory Vein Ligation Increased Fistula Caliber after Accessory Vein Ligation Cephalic Radial Anastomosis Accessory Accessory Vein: Coil Embolization Large Accessory Vein Stealing Flow from the Fistula Delivered percutaneously through accessed fistula Stainless Steel or Platinum Thrombogenic Synthetic fibers Can cause thrombophlebitis 7

8 Accessory Vein Treatment: Coil Embolization Accessory Vein Treatment: Coil Placement and Follow up Fistulagram Selective Catheterization of the Accessory Vein (catheter follows guidewire) Contrast injection confirms catheter is in the accessory vein Deployment of 6 mm coil Final fistulagram with negligible flow into accessory vein Outflow Fistula Complications Often become noticeable after regular use Due to venous stenosis downstream from the cannulation sites Prolonged bleeding Poor clearance High venous pressure Swelling of the extremity Thrombosis Fistula Examination Normal fistula Very soft with a continuous thrill Easily compressible with instant pressure increase When arm is raised - collapses, becomes flat Stenosis Increased pulse and firm pressure to touch Distended When arm is raised Distal to lesion - distended Proximal to lesion - collapsed Outflow Fistula Stenosis Proximal Cephalic Stenosis Brachiocephalic fistula *courtesy G. Beathard 8

9 Anatomy of the Proximal Cephalic Vein Resolved Stenosis Post Angioplasty BEFORE AFTER Severe mid fistula stenosis Brachiocephalic AV Fistula Results of Successful Angioplasty BEFORE AFTER What about the clotted fistula? Wider range of issues with AVF declotting K-DOQI 2000 difficult to treat Surgery or percutaneous efforts do not offer good results K-DOQI 2006 (Practice guideline 5.5) Treatment of thrombosis should start as early as possible Delaying procedure progressive growth of the thrombus short-term catheter more likely longer period of contact between thrombus and vessel wall = increased risk that extraction of thrombus may further damage the endoluminal layer Irregular Anatomy Variable location of the stenosis(es) Stenosis(es) more difficult to traverse Large volume of clot Large aneurysms Narrow time window for salvage *Turmel-Rodrigues KI 57 (2000) 9

10 Graft vs. AVF Declotting Clot volume is potentially very large in dilated fistulae 81 mm Graft (smooth contour) Fistula clot at the anastomosis *Gray et al, Dialysis Access *images from T. Vesley 33 mm Aspiration/Thrombectomy Technique *images from T. Vesley Thromboaspiration Products Why declot fistulae? More challenging in fistulae than grafts, but results are more rewarding Better long-term patency has been achieved in the largest series to date as long as the underlying stenoses are sufficiently dilated: 1-year primary patency rates of 50% and secondary patency rates of 80% have been reported* *Turmel-Rodrigues L, KI 2000; 57(3) 10

11 Central Venous Stenosis Catheter Related Central Stenosis Cause of access dysfunction and patient morbididty Becoming more common Pacemakers Defibrillators Ports/PICCs Dialysis Catheters *images from T. Vesley Defibrillator/Pacemaker Wires Ideally fistula should be on contralateral side Coexisting heart failure and tendency to volume overload can aggravate swelling Case Study Left Forearm Graft with Extremity Swelling Successful Central Vein Recanalization with Venous Angioplasty and Stent Placement The right subclavian vein was selectively catheterized and SVC angiogram was repeated The SVC still did not opacify; all central flow was via small chest wall vein collaterals and jugular reflux was noted This is a 3 year old right forearm loop graft; exam shows significant extremity swelling with a high pitched systolic only bruit at the elbow Fistulogram shows stenosis at the venous anastomosis (red arrow) and complete central venous obstruction at the junction of the right subclavian and brachiocephalic veins (blue arrow). The SVC was not seen. 11

12 Pre stent The complete occlusion was crossed with a glidewire using a 7 French guiding catheter (red arrow) for support SVC angiogram confirmed patency of the proximal SVC/right atrium (blue arrow) A 260 cm wire was parked in the IVC (green arrow) The lesion was dilated with a 4 mm balloon (yellow arrow) in anticipation of larger diameter PTA/stent placement Sub maximal dilation of lesion with 12 mm balloon showing deformity (green arrow); subsequently dilated to full effacement with 9 mm Conquest balloon (not shown) Follow up angiogram with residual stenosis (red arrow) 12 mm by 60 mm stent placed (blue arrow) Case Study Difficult Central Venous Dialysis Catheter Placement Stent was post dilated to 12 mm (blue arrow) Venous anastomosis stenosis was corrected (red arrow) Final central angiogram revealed patency with no residual stenosis (green arrow) Pt referred for poor flow from catheter and bleeding from chest wounds Catheter had been exchanged over a wire with new exit site created 24 hours prior by hospital radiology due to catheter exit site infection? Why left side catheter not considered Pt does have history of > 10 central dialysis catheters Left IJ punctured and wire passed centrally Wire appears to cross diaphragm, however, resistance is met; thus, angiogram pursued 12

13 Wire was actually in a small chest wall vein (?internal thoracic or cardiophrenic vein) Large azygous vein noted Severe stenosis in SVC noted (red arrow) Wire remanipulated into IVC (with difficulty) and then left innominate vein/svc stenosis dilated with 12 mm PTA balloon Follow up at 4 weeks Post angioplasty film and then subsequent dialysis catheter placement with catheter removal from the right side DIALYSIS CATHETERS Types of Catheters Temporary Intended for short term use: 1 session 2 weeks Flow rates ml/min Tunneled or cuffed Intermediate use: 2 weeks 1+ years Flow ml/min Implanted Ports Limited application Expensive Require special training 13

14 Tunneled Catheter: Early and Late Complications Importance of Tip Location Placement Related Kinks Air embolism Inappropriate tip placement Pneumothorax/Hemothorax Delayed malfunction Fibrin sheath formation Thrombosis Infection Local Systemic Central veins injury Stenosis Thrombosis Atrial thrombus Catheter tip embolization Others Exsanguanation it fell out *from Dialysis Access, Gray et al Catheter tip position is crucial A smooth curve of the catheter is essential Fibrin Sheath and Thrombus Formation inhibits flow Fibrin Sheaths Prevent Aspiration: Mechanism of Action 14

15 Treatment of the dysfunctional catheter Dialysis Catheters & Fibrin Sheaths Angiography confirms presence of sheath Blood flow < 300 ml/min at prepump arterial pressure 250 mm Hg Repositioning Thrombolytics intraluminal lytic intra/inter dialytic lock protocol intracatheter thrombolytic infusion Catheter exchange with sheath disruption, when appropriate K-DOQI Guideline 7 Fibrin sheath due to a left sided catheter Fibrin Sheath Therapy Use of angioplasty balloon Contrast injection after sheath removal Tip Separation: Catheter 15

16 Chronic Antibiotic/Alcohol Ointment Use Dialysis Catheter Related Infection Local Exit Site Tunnel Ifection Systemic Bacteremia Endocarditis Osteomyelitis Discitis Epidural Abscess Catheter Infections & K-DOQI 2006 Guideline 7 Catheters should be exchanged (over the wire) as soon as possible ( 72 hrs of antibiotic initiation in most instances)* Does not require a negative blood culture result before the exchange F/U cultures 1 week after cessation of antibiotic therapy Alternative = combining systemic antibiotics in conjunction with antibiotic locks *Mokrzycki et al, NDT (17), 2002 Catheter Infection Treatment Overview Exit site with (-) blood cx Antibiotics/local care?exchange/new tunnel Tunnel with (-) blood cx (+) blood cultures & fever antibiotics Catheter Infection IV antibiotics move catheter site Exchange cath < 72 hrs Severe symptoms/sepsis Remove catheter DIALYSIS SYNTHETIC GRAFTS The Original Scribner Shunt *courtesy of University of Washington 16

17 Natural history of grafts in dialysis patients Physical Exam AVG Detecting the Direction of Flow Repeated studies show that the average graft will be abandoned within 24 months Most grafts will require procedural intervention within 6 months Allon et al, KI 62(4), 02 Occlude graft at apex of loop, palpate for pulse on both sides of occulusion point for pulse Thrill diminishes Becomes pulsatile Occlude here *courtesy of G. Beathard Detecting Venous Stenosis 100% Outflow Stenosis Venous anastamosis of a synthetic graft High pitched discontinuous bruit Pulse is very forceful Strong thrill Treatment with angioplasty after passage of stenosis with guidewire Straight line flow post angioplasty 17

18 Secondary AV Fistula Sleeves Up Physical Examination at Dialysis AVF Created Following a forearm AV Graft Brachiocephalic or Brachiobasilic Created Using Venous Drainage of AV Graft Venous changes due to high flow from AVG Outflow vein maturation similar to AVF vein Secondary AVF may still require maturation time especially if transposition needed (brachio-basilic) Requires sleeves up examination at dialysis and a coordinated team approach (RN, Nephrologist, Surgeon) *image from L. Spergel Draining veins excellent candidates for Secondary AVF creation Secondary AVF Candidates in Prevalent Graft Patients Shoulder Cephalic Vein Elbow Basilic Vein Graft at Venous Anastamosis *Sands et al, NKF, 2001 How about Stents? K-DOQI guideline 6 If angioplasty of the same lesion twice within 3 months, consider surgical revision if appropriate surgical candidate If angioplasty fails, stents may be useful in the following situations: Surgically inaccessible lesion Contraindication to surgery Angioplasty-induced vascular rupture Stents are not FDA approved for use in peripheral veins Non-Covered vs. Covered Stents Non-Covered Stents No difference in patency vs PTA alone at 6-12 mos.* If intra-access, can NOT cannulate Cost $ Covered Stents Improved patency vs. PTA alone at 6 mos.**???better patency at 12 mos.??? Can cannulate if intra-access Treat pseudoaneurysms Cost ~$2500!! *Gray, et al. JVIR 1997; *Vogel, et al. JVIR 2004 **Haskal, et al. JVIR

19 stent fatigue complete fracture partial fracture Metal Stent Failure Novel use of a Covered Stent: Pseudoaneurysm in AVG oblique view metal fatigue early fracture *images from T. Vesley complete fracture Post Placement of Covered Stents Optimal HD Access Management Bringing all the Pieces Together Management of vascular access complications relies on a multidisciplinary approach...the goal of these management efforts is the preservation of vascular access NKF-K/DOQI guidelines 2000 Management of Complications: Guidelines emergent access procedures over 3 months in a busy access center Emergent defined as absence of functioning access for planned hemodialysis (i.e. thrombosed AV access (~50%) or non functioning catheter) Emergent cases represented ~20% daily case load 19

20 Outpatient VACs Timely and Successful Procedures Overall clinical success 95% Time from referral to procedure 24 hrs 90% Time from referral to dialysis 48 hrs 90% 14,000+ cases (11 centers, 29 nephrologists, all cases performed in 2003) Overall success rates 90+%, Complication rate 3.5% Interventional Nephrology Procedures and Complications Catheter Procedures 29% PTA 36% Declot 35% (mainly grafts) Complications Minor 3.3% Major 0.3% SUMMARY Vascular access is the sine qua non of hemodialysis and is of paramount clinical and economic importance Interventional Nephrology has evolved and responded to address dire needs The indicators of access dysfunction are readily available Physical examination Real time problems at hemodialysis Fistula Maturation is vital in creating appropriate AV access SUMMARY (continued) Fistula creation and prevalence are appropriately increasing Vigilance is required to ensure fistula maturation, patency, and salvage Cannulation Expertise is crucial (Buttonhole/self cannulation becoming more commonplace) Prospective surveillance with correction of stenosis may improve patency rates and decrease the incidence of thrombosis Team approach to access management is crucial What Can the HD RN Do? Early referral and expedient care can help prevent complete AV access failure and the problems patients face as a result 20

21 Perform a Physical Assessment for Each Access at Every Dialysis What Can the HD RN Do? Be a Patient Advocate Fistula First! Remember Buttonholes and Sleeves up Know your patients access and examine it regularly Inspection/Palpation/Auscultation (expended time = 1 minute) Compare and contrast the condition of the access to previous assessments Use exam findings to corroborate clinical findings at dialysis (pressures, clearance, etc.) It is 80% correct in predicting a need for intervention when done well A patient s access has a lot to show and say so Look, Listen, and Feel 21