EFFECTIVENESS OF VASCULAR ACCESS MONITORING

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EFFECTIVENESS OFVASCULAR ACCESS MONITORING

• William D. Paulson, MD
• Sunanda J. Ram, PhD
• Jack Work, MD
• Steve Jones, PhD
• Division of Nephrology and Hypertension
• LSU Health Sciences Center
• Shreveport, LA
• Paulson, Ram, Zibari Vascular Access Anatomy,
  examination, management. Semin Nephrol 22
  183-194, 2002

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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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THE PROBLEM ACCESS SURVIVAL
Allon KI 2001
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RATIONALE OF MONITORING

• PROGRESSIVE STENOSIS
• INCREASED GRAFT RESISTANCE
• DECREASED Qa, INCREASED VP, STASIS
• GRAFT THROMBOSIS FAILURE

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CURRENT DOGMA

• GRAFTS SHOULD BE MONITORED FOR HEMODYNAMICALLY
  SIGNIFICANT STENOSIS
• MONITORING COMBINED WITH CORRECTION IMPROVES
  PATENCY AND DECREASES THROMBOSIS
• NKF-K/DOQI (2001)

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MONITORING NOT ROUTINELY ADOPTED

• MONITORING METHODS ARE GENERALLY TEDIOUS AND/OR
  INTRUSUVE
• NO REIMBURSEMENT
• INADEQUATE STAFFING
• SKEPTICISM THAT MONITORING IS EFFICACIOUS

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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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MONITORING METHODS

• PHYSICAL EXAM
• RECIRCULATION
• VENOUS PRESSURE
• DYNAMIC
• STATIC
• ARTERIAL PRESSURE
• STATIC
• Qa
• DILUTION METHODS
• DUPLEX ULTRASOUND
• ANATOMY
• DUPLEX ULTRASOUND
• ANGIOGRAPHY

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VENOUS ARTERIAL PRESSURES
Besarab Dialysis Access 2002
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Qa BY ULTRASOUND DILUTION
Yeun Depner Dialysis Access 2002
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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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WHAT DETERMINES Qa?
CONCLUSIONQa MONITORING REQUIRES REPRODUCIBLE
CONDITIONS
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2 REPRESENTATIVE PATIENTS
DeSoto AJKD 2001
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Qa vs. MAP HCT
Jones Paulson ASN 2001
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Qa IS NOT STABLE
Paulson AJKD 2000
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RAPID CHANGE IN Qa
Rehman AJKD 1999
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WOULD YOU USE THESE TESTS?

• ?Qa -60 to 80
• Schneditz NDT, 1998
• Rehman AJKD, 1999
• DeSoto AJKD, 2001
• EQUIVALENT CHANGES
• Na 56 to 252 mEq/L
• Hct 16 to 72

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RAPID RATE OF STENOSIS IN NEW GRAFTS
THROMBOSIS IN lt90 DAYS, N 17
THROMBOSIS IN 90 DAYS, N 21
Atray ASN 2001
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IMPLICATIONS FOR Qa MONITORING

• Qa HAS POOR REPRODUCIBILITY
• STRONGLY INFLUENCED BY HEMODYNAMIC EVENTS
• STENOSIS OFTEN PROGRESSES RAPIDLY IN NEW GRAFTS
• IS Qa MONITORING EFFECTIVE?

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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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STUDIES THAT SUPPORT MONITORING

• NONRANDOMIZED
• VENOUS PRESSURE
• SCHWAB KIDNEY INT 1989
• BESARAB KIDNEY INT 1995
• RANDOMIZED
• Qa
• SANDS ASAIO J 1999
• STENOSIS
• MAYER VASC SURG 1993
• MARTIN J VASC INTERVENT RADIOL 1999

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Qa MONITORINGEFFECT ON ACCESS MORBIDITY COSTS

• REPORTED MONITORING RESULTED IN
• REDUCED THROMBOSIS RATE
• REDUCED HOSPITALIZATION
• REDUCED COST
• NO IMPROVEMENT IN GRAFT SURVIVAL
• STUDY DESIGN
• NONRANDOMIZED
• SEQUENTIAL CONTROL MONITORING GROUPS

MCCARLEY KI 2001
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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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DEFICIENCIES OF STUDY DESIGNS

• NO CONTROL GROUP
• HISTORICAL OR SEQUENTIAL CONTROL GROUP
• SMALL N
• INAPPROPRIATE STATISTICAL TESTING

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HISTORICAL OR SEQUENTIAL CONTROL GROUPS

• ADVANTAGES
• GENERATE HYPOTHESIS
• VALID WHEN OUTCOME OF CONTROL GROUP IS UNIFORM
• ALLOWS SMALLER N
• COMPLETE STUDY MORE QUICKLY
• DISADVANTAGE
• OVERESTIMATION OF TREATMENT EFFECT

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NEED TO MAKE THE RIGHT COMPARISONS

• DURING WW II, RESCUE WORKERS DIGGING IN THE
  RUINS OF AN APARTMENT HOUSE BLOWN UP IN THE
  LONDON BLITZ FOUND AN OLD MAN LYING NAKED IN A
  BATHTUB. HE SAID TO HIS RESCUERS "YOU KNOW, THAT
  WAS THE MOST AMAZING EXPERIENCE I EVER HAD. WHEN
  I PULLED THE PLUG THE WATER STARTED DOWN THE
  DRAIN, THE WHOLE HOUSE BLEW UP!"
• 
  GORDIS EPIDEMIOLOGY 2000

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WE ARE ALL BIASED

• WE BELIEVE WE CAN MAKE A DIFFERENCE
• WE ARE BIASED IN FAVOR OF INTERVENTION
  TREATMENT
• WE MINIMIZE OR IGNORE POTENTIAL ADVERSE EFFECTS
  OF INTERVENTION TREATMENT

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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• RESULTS OF CLINICAL STUDIES
• IMPORTANCE OF CLINICAL STUDY DESIGN
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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PREDICTIVE ACCURACY OF Qa
Paulson AJKD 2002
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DEFINITIONS OF PREDICTIVE ACCURACY

• SENSITIVITY
• FOR THROMBOSED GRAFTS, WITH LOW Qa
• FALSE POSITIVE RATE
• FOR PATENT GRAFTS, WITH LOW Qa

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HYPOTHETICAL ROC CURVE
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PREDICTION OF THROMBOSIS BY Qa
Paulson ASN 2002
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PREDICTION OF GRAFT FAILURE BY Qa
McDOUGAL KI 2001
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PREDICTION OF THROMBOSISOR FAILURE BY ?Qa
Paulson ASN 2002
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PREDICTION OF THROMBOSISQa ?Qa COMBINED
Paulson AJKD, 2000, 2001
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UF MAP INFLUENCE THROMBOSIS
Paulson AJKD 2002
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ACCURACY OF DYNAMIC VP IN PREDICTING THROMBOSIS
OR FAILURE
Frinak AJKD 2002
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ACCURACY OF STATIC VP IN PREDICTING THROMBOSIS OR
FAILURE
Dember KI 2002
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STATIC VPPREEMPTIVE REPAIR OF STENOSIS

• 64 PATIENTS WITH HIGH VP
• OBSERVATION GROUP (N 32) INTERVENTION GROUP (N
  32)
• REPAIR FOR THROMB OR
  REPAIR GRAFT
• CLINICAL DYSFUNCTION
• 3.5 YEAR FOLLOW-UP
• 14 GRAFTS ABANDONED 14 GRAFTS
  ABANDONED

Dember ASN 2002
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INFLUENCE OF PREEMPTIVE INTERVENTION ON GRAFT
SURVIVAL
Ram ASN 2001
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SUMMARY OF LSU STUDY

• INTERVENTION BASED UPON Qa OR STENOSIS DID NOT
  IMPROVE GRAFT SURVIVAL
• SEVERAL FACTORS MAY EXPLAIN RESULT
• Qa WAS AN INACCURATE PREDICTOR OF THROMBOSIS
• CONTROL GROUP HAD HIGH PREEMPTIVE PTA RATE
• POTENTIAL HARM OF UNNECESSARY PTA
• ACTIVE INVOLVEMENT OF DIALYSIS STAFF IN
  MANAGEMENT OF GRAFTS MAY BE MORE IMPORTANT THAN
  MONITORING BASED UPON ALGORITHMS.

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MONITORING OUTLINE

• CURRENT DOGMA
• NKF K/DOQI CLINICAL PRACTICE GUIDELINES
• MONITORING METHODS
• FACTORS THAT INFLUENCE EFFECTIVENESS OF
  MONITORING
• IMPORTANCE OF CLINICAL STUDY DESIGN
• RESULTS OF CLINICAL STUDIES
• SUMMARY CONCLUSION
• WHERE TO WE GO FROM HERE?

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WHY DO PREEMPTIVE INTERVENTION?

• BENEFITS
• INCREASE DIALYSIS EFFICIENCY
• FEWER CENTRAL VEIN CATHETERS
• REDUCE THROMBOSIS RATE
• REDUCE HOSPITALIZATION COSTS (?)
• DISADVANTAGES
• LACK OF ACCURATE MONITORING METHOD
• IS APPARENT BENEFIT OF MONITORING DUE TO HIGH
  PREVALENCE OF STENOSIS?
• MAY NOT PROLONG GRAFT LIFE
• MORE PROCEDURES
• HIGHER COSTS FROM UNNECESSARY PROCEDURES
• UNNECESSARY PROCEDURES MAY SHORTEN GRAFT LIFE

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POTENTIALLY HARMFUL FALSE POSITIVE

• STABLE STENOSIS
• HEMODYNAMICALLY INDUCED DECREASED IN Qa
• ANGIOPLASTY
• STIMULATION OF NEOINTIMAL HYPERPLASIA
• GRAFT FAILURE

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CONCLUSION

• STAFF COMMITTED TO ACCESS MAINTENANCE SURVIVAL
  IS KEY
• PHYSICAL EXAM AND CLINICAL CORRELATION MAY
  PROVIDE MOST OF BENEFIT
• HIGH PTA RATE CAN REDUCE THROMBOSIS
• POTENTIAL HARM OF UNNECESSARY PTA
• IT IS NOT ESTABLISHED THAT MONITORING PROLONGS
  GRAFT LIFE
• RANDOMIZED CONTROLLED TRIALS ARE NEEDED