Ruolo della clinica e del laboratorio nella diagnosi di malfunzionamento di una FAV

Transcription

1 Ruolo della clinica e del laboratorio nella diagnosi di malfunzionamento di una FAV Carlo Basile Division of Nephrology and Dialysis Miulli General Hospital, Acquaviva delle Fonti, Italy

2 VASCULAR ACCESS MONITORING AND SURVEILLANCE Monitoring refers to the examination and evaluation of the vascular access (VA) by means of physical examination to detect physical signs that would suggest the presence of pathology Surveillance refers to periodic evaluation of the VA by means of tests, that may involve special instrumentation, for which an abnormal test result suggests the presence of pathology

3 Achneck et al, Semin Dial 2010

4 Achneck et al, Semin Dial 2010

5 Achneck et al, Semin Dial 2010

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7 AV FISTULA, ANATOMICAL VARIETIES Side to side anastomosis V Cephalic Distal Proximal V Cephalic Side to end anastomosis End to end anastomosis

8 Proximal VA more likely results in very high blood flow, increasing the risk of steal syndrome and cardiac failure Upper arm Bend of the elbow Forearm Risks associated with AVF creation are related to its location Distal VA more likely results in lower blood flow and high incidence of early non function 8

9 Risks associated with AVF creation are related to the size of the anastomosis in a small AVF, the increase in cardiac output is equal to the AVF Qa in a large AVF, the increase in cardiac output may exceed AVF Qa

10 and to the anastomosis angle

11 Ene-Iordache, NDT 2013

12 In AVF stenoses occur in specific sites, consistently related to the local hemodynamics determined by vessel geometry and blood flow pattern CJASN 2013

13 DIALYSIS ACCESS DYSFUNCTION Vascular access failure is the most common reason for hospitalization among HD patients The economic burden of VA failure is estimated to be greater than 1 billion dollars per year and continues to grow Yevzlin, Asif and Agarwal, Int J Nephrol

14 Ruolo della clinica nella diagnosi di malfunzionamento di una FAV

15 Besarab A, Karim J, Frinak S in : Agarwal & Asif et al. Interventional Nephrology Mc Graw Hill, NY 2012 the presence of stenosis alone is not sufficient to define access dysfunction. hemodynamically insignificant stenoses are dilated needlessly because they are merely there in the accesses that are performing well. 15

16 - CLINICAL MONITORING a) Physical examination b) inadequate delivery of dialysis ( serum potassium, serum creatinine, Kt/V, urea reduction ratio) c) Abnormalities detected by dialysis staff - SURVEILLANCE Vascular access screening tools (assessing the access by means of noninvasive methods requiring special equipment) a) Directly measured or derived intra-access pressures b) Access recirculation c) Access blood flow rate (Qa) d) Duplex ultrasound (DU) Courtesy of Nicola Tessitore 16

17 K/DOQI Clinical Practice Guidelines for Vascular Access, Updates Physical examination (monitoring): Access patency should be ensured before each treatment. Physical examination should be used to detect dysfunction in fistulae and grafts at least monthly by a qualified individual. (B) 4.3 Surveillance in fistulae: Preferred: Direct flow measurements. (A) Duplex ultrasound. (A) 4.4 When to refer for evaluation (diagnosis) and treatment: An access flow rate less than 600 ml/min in grafts and less than 400 to 500 ml/min in fistulae. (A) 17

18 Physical examination of the access by an experienced individuals has high sensitivity and specificity Unfurtunately such high-skill level is missing in most dialysis centers Kumbar, Int J Nephrol

19 CLINICAL MONITORING Inspection Palpation Auscultation Physical examination: the forgotten tools G Beathard 19

20 Inspection Salman and Beathard, CJASN

21 Salman and Beathard, CJASN

22 Salman and Beathard, CJASN

23 Salman and Beathard, CJASN

24 PHYSICAL EXAMINATION Augmentation test: Evaluates the inflow. Arm Elevation: Evaluates the outflow.

25 PULSE AUGMENTATION TEST: EVALUATES THE INFLOW A.The AV fistula is occluded B. The pulse is assessed for augmentation The degree of increase in pulse intensity is directly proportional to the quality of the access inflow (and, then, to the severity of the stenosis) Salman and Beathard, CJASN

26 PHYSICAL EXAMINATION Augmentation test: Evaluates the inflow. Arm Elevation: Evaluates the outflow.

27 Arm elevation stenosis With a normal outflow, the fistula will collapse when the arm is elevated With stenosis, the portion of AVF peripheral to the lesion will stay distended. That portion central to the site will collapse normally. 27

28 Ruolo del laboratorio nella diagnosi di malfunzionamento di una FAV

29 - CLINICAL MONITORING a) Physical examination b) inadequate delivery of dialysis ( serum potassium, serum creatinine, Kt/V, urea reduction ratio) c) Abnormalities detected by dialysis staff - SURVEILLANCE Vascular access screening tools (assessing the access by means of noninvasive methods requiring special equipment) a) Directly measured or derived intra-access pressures b) Access recirculation c) Access blood flow rate (Qa) d) Duplex ultrasound (DU) Courtesy of Nicola Tessitore 29

30 K/DOQI Clinical Practice Guidelines for Vascular Access, Updates Physical examination (monitoring): Access patency should be ensured before each treatment. Physical examination should be used to detect dysfunction in fistulae and grafts at least monthly by a qualified individual. (B) 4.3 Surveillance in fistulae: Preferred: Direct flow measurements. (A) Duplex ultrasound. (A) 4.4 When to refer for evaluation (diagnosis) and treatment: An access flow rate less than 600 ml/min in grafts and less than 400 to 500 ml/min in fistulae. (A) 30

31 MISURA DELLA PORTATA DELLA FAV Tecniche di diluizione dell indicatore 1- Ultrasonodiluizione (Krivitski, KI 1995) 2- Termodiluizione (Schneditz, NDT 1999) 3- Otticodiluizione (Lindsay, KI 1996) 4- Conducibilità (Gotch, ASAIO J 1998) Con inversione linee 1- Otticodiluizione transcutanea (Steuer, KI 2001) 2- Infusione di glucosio (Magnasco, NDT 2002) Senza inversione linee Altri metodi 1- Eco-Doppler (Sands, ASAIO J 1992) 2- Risonanza magnetica (Laissy, Invest Radiol 1999)

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33 R%=BUNs-BUNa/BUNa-BUNv

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35 NKF-K/DOQI: ACCESS FLOW PROTOCOL SURVEILLANCE Access flow measured by saline ultrasound dilution, conductance dilution, thermal dilution, doppler or other technique shouldbe performed monthly. AV graft and AV fistula: access flow less than 600 ml/min: the patient should be referred for fistulogram access flow less than 1,000 ml/min that has decreased by more than 25% over 4 months should be referred for fistulogram.

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37 Conclusions A VA blood flow rate (Qa) < 500 ml/min seems to be the most appropriate threshold for performing angiography in patients with AVFs It is recommended that clinicians arrange angiography when Qa is < 500 ml/min in AVFs.

38 SURVEILLANCE: THE PROSAND CONS Tessitore / Paulson

39 Vascular access surveillance: an ongoing controversy W Paulson, L Moist and C Lok Kidney Int 2011 the surveillance as usually practiced may not improve access outcomes, is costly, and may even be harmful. current evidence does not support the concept that all accesses should undergo routine surveillance with intervention.

40 THE RISE AND FALL OFACCESS BLOODFLOW SURVEILLANCEIN IN ARTERIOVENOUS FISTULAS Qa has a fairly good reproducibility (CV 5,5%) Qa shows an excellent-to to-good accuracy for stenosis Qa surveillance affords a 2- to 3-fold reduction in the risk of thrombosis (when Qa criteria highly sensitive to stenosis are considered) Tessitore et al, Semin Dial 2014

41 IL RASOIO DI OCCAM Non moltiplicare gli elementi più del necessario Si fa inutilmente con molte cose quello che si può fare con poche cose William of Ockham

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