**Vascular Access for Hemodialysis**

Konstantinos Pantelias and Eirini Grapsa

*University of Athens Greece* 

#### **1. Introduction**

44 Technical Problems in Patients on Hemodialysis

Kakkos, K.S.; Andrzejewski, T.; Haddad, J.A.; Haddad, G.K.; Reddy, D.J.; Nypaver, T.J.;

Kherlakian, G.M.; Roedersheimer, L.R.; Arbaugh, J.J., et al, (1986). Comparison of

Lumsden, B.M.; Chen, C. (1997). Accelerated neointimal hyperplasia in haemodialysis access

Masuda, H.; Bassiouny, H., et al. (1989). Artery wall restructuring in response to increased

Matsuura, J.H. ; Rosenthal, D. ; Clark, M., et al. (1998). Transposed basilic vein versus

Palder, S.B.; Kirkman, R.L.; Whittemore, A.D., et al. (1985). Vascular access for hemodialysis:

Pisoni, R.; Young, E.W.; Dykstra, D., et al. (2002). Vascular access use in Europe and the

Porter, J.A.; Sharp, W.V.; Walsh, E.J. (1985). Complications of vascular access in a dialysis

Schanzer, H.; Schanzer, A. (2004). Vascular access for dialysis, In Ascher, E. (Ed.), *Haimovici's* 

Segal, J.H.; Kayler, L.K.; Henke, P.; Merion, R.M.; Leavey, S.; Campbell, D.A. Jr. (2003).

Sladen. J; Mandl. M., et al. (1985) Fibroblast inhibition: a new and treatable cause of prosthetic graft failure. *Am J Surg*, No.149 (1985), pp. 588–590, ISSN 0002-9610 Stiru, O.; Iliescu V.A. & Dorobantu, L.F. (2006). *Tehnici de fistule arteriovenoase native la nivelul* 

The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (2001).

Woo, K.; Farber, A.; Doros, G.; Killeen, K. & Kokanzadeh, S. (2007). Evaluation of the

Zarins, C.K.; Xu, C. ; Bassiouny, H.S.; Glagov, S. (2004). Intimal hyperplasia, In Ascher, E.

population*. Curr Surg*, No.42 (1985), pp. 298-300, ISSN 0149-7944

*Am J Kidney Dis*, No.42 (2003), pp. 151-157, ISSN 0272-6386

flow. *Surg Forum*, No.40 (1989), pp. 285–286, ISSN 1522-666

*Surg*, No.47 (2008), pp. 407-414, ISSN 0741-5214

973-708-428-6, Bucharest, Romania

Malden, Massachusetts, USA

(2001), pp. 137-181, ISSN 0272-6386

(2007), pp. 94-101, ISSN 0741-5214

978-0-632-04458-0, Malden, Massachusetts, USA

Bucharest, Romania

0003-4932

1523-1755

No.176 (1998), pp. 219-221, ISSN 0002-9610

Scully, M.M.;RN & Schmid, D.L. (2008). Equivalent secondary patency rates of upper extremity Vectra Vascular Access Grafts and transposed brachial-basilic fistulas with aggressive access surveillance and endovascular treatment. *J Vasc* 

autogenous fistula versus expanded polytetrafluoroethylene graft fistula for angioaccess in hemodialysis. *Am J Surg,* No.152 (1986), pp. 238-243, ISSN 0002-9610

grafts, In: Henry ML, Ferguson RM, (Ed.), *Vascular access for haemodialysis*, 5th ed., pp. 43-50, WL Gore and Precept Press, ISBN 0-944496-50-4, Chicago, Illinois, USA Lupu, G.; Terteliu, F.; Bulescu, I. (2009). Vascularizatia membrului superior, In Lupu, G.

(Ed.), *Anatomie – Membrele*, pp. 47, Editura Universitara "Carol Davila", ISBN 978-

polytetrafluoroethylene for brachial-axillary anteriovenous fistulas. *Am J Surg,*

Patency rates and results of revision. *Ann Surg,* No.202 (1985), pp. 235-239, ISSN

United States: results from the DOPPS. *Kidney Int,* No.61 (2002), pp. 305-316, ISSN

*Vascular Surgery,* 5th ed., pp.1015-1030, Blackwell Science, ISBN 978-0-632-04458-0,

Vascular access outcomes using the transposed basilic vein arteriovenous fistula.

*membrului superior*, Editura Universitara "Carol Davila", ISBN 973-708-126-9,

Clinical practice guidelines for vascular access: update. *Am J Kidney Dis*, No.37

efficacy of the transposed upper arm arteriovenous fistula: A single institutional review of 190 basilic and cephalic vein transposition procedures. *J Vasc Surg,* No.46

(Ed.), *Haimovici's Vascular Surgery,* 5th ed., pp. 165-167, Blackwell Science, ISBN

A progressive rise in the number of patients accepted for renal replacement therapy has been reported world wide [1]. Permanent vascular access (VA) is the life-line for the majority of these patients, when hemodialysis is the treatment of choice. Thus, the successful creation of permanent vascular access and the appropriate management to decrease the complications is mandatory. A well functional access is also vital in order to deliver adequate hemodialysis therapy in end-stage renal disease (ESRD) patients. Unfortunately, despite the advances in hemodialysis technology, the introduction of the polytetrafluoroethylene (PTFE) graft and the cuffed double lumen silicone catheter were the only changes in the field of vascular access in the last years. However the cost of vascular access related care was found to be more than fivefold higher for patients with arteriovenous graft (AVG) compared with patients with a functional arteriovenous fistula (AVF) [2]. It seems that the native arteriovenous fistula that Brescia and Cimino described in 1966, still remains the first choice VA [3]. Thereafter, vascular access still remains the "Achilles' heel" of the procedure [4] and hemodialysis vascular access dysfunction is one of the most important causes of morbidity in this population [5]. It has been estimated that vascular access dysfunction is responsible for 20% of all hospitalizations; the annual cost of placing and looking after dialysis vascular access in the United States exceeds 1 billion dollars per year [6, 7]. Nowadays, three types of permanent vascular access are used: arteriovenous fistula (AVF), arteriovenous grafts (AVG) and cuffed central venous catheters. They all have to be able to provide enough blood flow in order to deliver adequate hemodialysis, have a long use-life and low rate of complications. The native forearm arteriovenous fistulas (AVF) have the longest survival and require the fewest interventions. For this reason the forearm AV is the first choice, followed by the upper-arm AVF, the arteriovenous graft (AVG) and the cuffed central venous catheter as a final step [8-10].

#### **2. History of vascular access**

Vascular access for hemodialysis is closely associated with the history of dialysis. Glass needles were employed as vascular access when hemodialysis came into view in 1924. The first haemodialysis treatment in humans was carried out by Haas G. who used glass cannulae to acquire blood from the radial artery and reverting it to the cubital vein [11]. Venipuncture needles were used as means for blood acquisition from the femoral artery and its reinfusion to the patient by vein puncture, in 1943 by Kolff W. [12, 13]. Regular hemodialysis treatments were possible in 1950s through the use of a medical apparatus (Kolff 's twin-coil kidney [14] ), thus projecting the problem of a reliable, capable of repeated

Vascular Access for Hemodialysis 47

Dardik H., had worked with a new graft material: the human umbilical cord vein [31, 32]. Regrettably so, this material did not succeed in becoming a revolutionary graft material, due to its inadequate resistance against the trauma of repeated cannulation and its complications (aneurysm and infection). After the subclavian route for haemodialysis access was firstly introduced by Shaldon S et al in 1961, it was further processed in 1969 by Erben J et al, using the intraclavicular route [33]. In the next 20 years or so, the subclavian vein was the preferred access for temporary vascular access by central venous catheterization. Today, due to phlebographic studies revealing a 50% stenosis or occlusion rate at the cannulation site, subclavian route has been discarded. Subclavian stenosis and occlusion predispose to oedema

The first angioplasty described by Dotter CT et al who introduced a type of balloon, was immensely conducive to the resolution of one of the most significant predicaments in

In 1977, Gracz KC et al created the "proximal forearm fistula for maintenance hemodialysis", a variant of an AV anastomosis [36]. An adjustment of this AVF became quite significant in the old, hypertensive and diabetic patients on the grounds that it allows a proximal anastomosis with a low risk of hypercirculation [37]. In 1979 Golding A.L. et al developed a "carbon transcutaneous hemodialysis access device" (CATD), commonly known as "button", by which, blood access does not require needle puncture [38]. As a procedure of third choice, these devices were expensive and never gained widespread acceptance. Shapiro F.L. described another type of "button", a device similar to that

Years after the initial efforts to create the appropriate vascular access in order to perform a safe hemodialysis, modern Nephrologists have now the possibility to select the appropriate access for their patients. Thus, the first distinction is made between temporary and permanent VA [40]. Temporary VA with expected half-life less than 90 days, peripheral arteriovenous shunts and non cuffed double lumen catheters are included. Mid-term VA with expected half-life from 3 months to 3 years include veno-venous accesses (tunneled cuffed catheters and port catheter devices) and arteriovenous internal shunts, requiring vascular graft synthetic (PTFE) or biologic (saphenous vein, Procol, etc.) material ,or external shunt. Long-term VA with an expected half-life more than 3 years includes virtually the

When an urgent hemodialysis has to be performed, the need for an appropriate vascular access becomes immediate. This type of access must have some specific features such as ease of insertion and availability for immediate use. Two types of such accesses are currently available: non-tunnelled dialysis catheters and cuffed, tunnelled dialysis catheters (Figure 1-5). Double-lumen, non-cuffed, non-tunnelled hemodialysis catheters are the preferred method for immediate hemodialysis when a long-term access is not available. They are made of polymers which are rigid at room temperature to facilitate insertion but soften at body temperature to minimize vessel injury and blood vessel laceration. In order to minimize recirculation, the

native arteriovenous fistulas [4] and the new generation of PTFE grafts .

distance between the proximal and distal lumens should be at least 2cm [41].

of the arm, especially after creation of an AV fistula [34].

vascular surgery and vascular access surgery [35].

developed by Golding [39].

**3. Angioaccess classification** 

**3.1 Acute hemodialysis vascular access** 

use vascular access. Nowadays, the artery-side-to-vein-end-anastomosis has become a standard procedure [15]. In 1952, Aubaniac had described the puncture of the subclavian vein [16].

In the 60s, by using Alwall's experience, Quinton, Dillard and Scribner developed arteriovenous Teflon shunt [17]. This procedure involved two thin-walled Teflon cannulas with tapered ends inserted one into the radial artery and the other into the adjacent cephalic vein. The external ends were connected by a curved Teflon bypass tube. Later, the Teflon tube was replaced by flexible silicon rubber tubing. After the advancement of permanent vascular access, the possibility of maintenance hemodialysis was a fact and therefore a groundbreaking procedure.

In the subsequent years, many variants of the AV shunt were used, with the majority of them concerning temporary vascular access from the onset of chronic dialysis treatment, compensating for the time of AV fistula's absence or maturity. In 1961, Shaldon performed hemodialysis procedures by inserting catheters into femoral artery and vein, using the Seldinger-technique [18, 19]. Over time, vessels in different sites were used, including the subclavian, jugular and femoral vein.

In 1962 Brescia MJ described a 'simple venipuncture for hemodialysis' [20]. In 1963 Fogarty TJ et al invented an intravascular catheter with an inflatable balloon at its distal tip, designed for embolectomy and thrombectomy [21]. The first surgically created fistula was placed in 1965, followed by further 14 operations in 1966 [22]. In 1966 Brescia, Cimino, Appel and Hurwich published their paper about arteriovenous fistula. Appell had performed a side-to-side-anastomosis between the radial artery and the cephalic antebrachial vein. One year later, in 1967, Sperling M. et al reported the successful creation of an end-to-end-anastomosis between the radial artery and the cephalic antebrachial vein in the forearm of 15 patients using a stapler [23]. In the next few years this type of AV anastomosis received widespread acceptance. However this procedure was cast aside as first choice AV, due to the increasing numbers of elderly, hypertensive and diabetic patients with demanding vessels and high risk of steal syndrome. End-to-end-anastomoses are still a common place technique in revision procedures but it seems that they correlate with higher mortality risk due to infection [24].

In 1968 Röhl L. et al published thirty radial-artery-side-to-vein-end anastomoses [25]. After anastomosis was performed, the radial artery was ligated distal to the anastomosis, thus resulting in a functional end-to end-anastomosis. Today, the artery-side-to-vein-endanastomosis has become a standard procedure [15]. In 1970, Girardet R. [26] and Brittinger W.D. [27] described their experience with the femoral vein and artery for chronic hemodialysis. Experimental trials have been done by several authors in order to establish a permanent vascular access using subcutaneous tunnel. Brittinger W. was the first to implant a plastic valve as a vascular access in an animal model but unfortunately his efforts did not proceed to a human one [28]. Moreover, during the early 70s, Buselmeier T.J. developed a Ushaped silastic prosthetic AV shunt with either one or two Teflon plugged outlets which communicated to the outside of the body. The U-shaped portion could be totally or partially implanted subcutaneously [29]. Subsequently pediatric hemodialysis patients were extremely favored by this procedure. New materials for AV grafts were presented in 1972, one biologic and two synthetic. In 1976, Baker L.D. Jr. presented the first results with expanded PTFE grafts in 72 haemodialysis patients [30]. In the years to come, several publications indicated the benefits and the shortcomings of the prosthetic material in question, remaining the primary choice of graft for hemodialysis VA to date. The same year, two authors, Mindich B. and

use vascular access. Nowadays, the artery-side-to-vein-end-anastomosis has become a standard procedure [15]. In 1952, Aubaniac had described the puncture of the subclavian

In the 60s, by using Alwall's experience, Quinton, Dillard and Scribner developed arteriovenous Teflon shunt [17]. This procedure involved two thin-walled Teflon cannulas with tapered ends inserted one into the radial artery and the other into the adjacent cephalic vein. The external ends were connected by a curved Teflon bypass tube. Later, the Teflon tube was replaced by flexible silicon rubber tubing. After the advancement of permanent vascular access, the possibility of maintenance hemodialysis was a fact and therefore a

In the subsequent years, many variants of the AV shunt were used, with the majority of them concerning temporary vascular access from the onset of chronic dialysis treatment, compensating for the time of AV fistula's absence or maturity. In 1961, Shaldon performed hemodialysis procedures by inserting catheters into femoral artery and vein, using the Seldinger-technique [18, 19]. Over time, vessels in different sites were used, including the

In 1962 Brescia MJ described a 'simple venipuncture for hemodialysis' [20]. In 1963 Fogarty TJ et al invented an intravascular catheter with an inflatable balloon at its distal tip, designed for embolectomy and thrombectomy [21]. The first surgically created fistula was placed in 1965, followed by further 14 operations in 1966 [22]. In 1966 Brescia, Cimino, Appel and Hurwich published their paper about arteriovenous fistula. Appell had performed a side-to-side-anastomosis between the radial artery and the cephalic antebrachial vein. One year later, in 1967, Sperling M. et al reported the successful creation of an end-to-end-anastomosis between the radial artery and the cephalic antebrachial vein in the forearm of 15 patients using a stapler [23]. In the next few years this type of AV anastomosis received widespread acceptance. However this procedure was cast aside as first choice AV, due to the increasing numbers of elderly, hypertensive and diabetic patients with demanding vessels and high risk of steal syndrome. End-to-end-anastomoses are still a common place technique in revision procedures but it seems that they correlate with higher

In 1968 Röhl L. et al published thirty radial-artery-side-to-vein-end anastomoses [25]. After anastomosis was performed, the radial artery was ligated distal to the anastomosis, thus resulting in a functional end-to end-anastomosis. Today, the artery-side-to-vein-endanastomosis has become a standard procedure [15]. In 1970, Girardet R. [26] and Brittinger W.D. [27] described their experience with the femoral vein and artery for chronic hemodialysis. Experimental trials have been done by several authors in order to establish a permanent vascular access using subcutaneous tunnel. Brittinger W. was the first to implant a plastic valve as a vascular access in an animal model but unfortunately his efforts did not proceed to a human one [28]. Moreover, during the early 70s, Buselmeier T.J. developed a Ushaped silastic prosthetic AV shunt with either one or two Teflon plugged outlets which communicated to the outside of the body. The U-shaped portion could be totally or partially implanted subcutaneously [29]. Subsequently pediatric hemodialysis patients were extremely favored by this procedure. New materials for AV grafts were presented in 1972, one biologic and two synthetic. In 1976, Baker L.D. Jr. presented the first results with expanded PTFE grafts in 72 haemodialysis patients [30]. In the years to come, several publications indicated the benefits and the shortcomings of the prosthetic material in question, remaining the primary choice of graft for hemodialysis VA to date. The same year, two authors, Mindich B. and

vein [16].

groundbreaking procedure.

subclavian, jugular and femoral vein.

mortality risk due to infection [24].

Dardik H., had worked with a new graft material: the human umbilical cord vein [31, 32]. Regrettably so, this material did not succeed in becoming a revolutionary graft material, due to its inadequate resistance against the trauma of repeated cannulation and its complications (aneurysm and infection). After the subclavian route for haemodialysis access was firstly introduced by Shaldon S et al in 1961, it was further processed in 1969 by Erben J et al, using the intraclavicular route [33]. In the next 20 years or so, the subclavian vein was the preferred access for temporary vascular access by central venous catheterization. Today, due to phlebographic studies revealing a 50% stenosis or occlusion rate at the cannulation site, subclavian route has been discarded. Subclavian stenosis and occlusion predispose to oedema of the arm, especially after creation of an AV fistula [34].

The first angioplasty described by Dotter CT et al who introduced a type of balloon, was immensely conducive to the resolution of one of the most significant predicaments in vascular surgery and vascular access surgery [35].

In 1977, Gracz KC et al created the "proximal forearm fistula for maintenance hemodialysis", a variant of an AV anastomosis [36]. An adjustment of this AVF became quite significant in the old, hypertensive and diabetic patients on the grounds that it allows a proximal anastomosis with a low risk of hypercirculation [37]. In 1979 Golding A.L. et al developed a "carbon transcutaneous hemodialysis access device" (CATD), commonly known as "button", by which, blood access does not require needle puncture [38]. As a procedure of third choice, these devices were expensive and never gained widespread acceptance. Shapiro F.L. described another type of "button", a device similar to that developed by Golding [39].

#### **3. Angioaccess classification**

Years after the initial efforts to create the appropriate vascular access in order to perform a safe hemodialysis, modern Nephrologists have now the possibility to select the appropriate access for their patients. Thus, the first distinction is made between temporary and permanent VA [40]. Temporary VA with expected half-life less than 90 days, peripheral arteriovenous shunts and non cuffed double lumen catheters are included. Mid-term VA with expected half-life from 3 months to 3 years include veno-venous accesses (tunneled cuffed catheters and port catheter devices) and arteriovenous internal shunts, requiring vascular graft synthetic (PTFE) or biologic (saphenous vein, Procol, etc.) material ,or external shunt. Long-term VA with an expected half-life more than 3 years includes virtually the native arteriovenous fistulas [4] and the new generation of PTFE grafts .

#### **3.1 Acute hemodialysis vascular access**

When an urgent hemodialysis has to be performed, the need for an appropriate vascular access becomes immediate. This type of access must have some specific features such as ease of insertion and availability for immediate use. Two types of such accesses are currently available: non-tunnelled dialysis catheters and cuffed, tunnelled dialysis catheters (Figure 1-5). Double-lumen, non-cuffed, non-tunnelled hemodialysis catheters are the preferred method for immediate hemodialysis when a long-term access is not available. They are made of polymers which are rigid at room temperature to facilitate insertion but soften at body temperature to minimize vessel injury and blood vessel laceration. In order to minimize recirculation, the distance between the proximal and distal lumens should be at least 2cm [41].

Vascular Access for Hemodialysis 49

Central veins such as jugular, subclavian or femoral, can be used as insertion routes of these catheters [42]. The femoral artery can be used as an access central vein when all other central veins have been excluded. For their insertion a modified Seldinger guide wire technique is used. In order to minimize immediate insertion complications, image guided assistance is recommended. Non-cuffed catheters are also suitable for use at the bedside of the patient

The 2006 National Kidney Foundation Dialysis Outcomes Quality Initiative (K/DOQI) guidelines recommend, after internal jugular or subclavian vein insertion, identifying radiographically any potential complications and confirming tip placement prior to either anticoagulation or catheter use [45]. Nowadays, the subclavian catheters should be generally

The maximum blood flow with this class of catheters is usually blood pump speeds of 300 mL/min, with an actual blood flow of 250 mL/min or less [46, 47]. Femoral catheters have to be at least 18 to 25 cm in length in order to have lower recirculation. The routine use-life of these catheters varies depending on the site of insertion. Generally speaking, internal jugular catheters are suitable for two to three weeks of use, while femoral catheters are usually used for a single treatment (ambulatory patients) or for three to seven days in bed bound patients [48]. However, the KDOQI guidelines suggest that non-cuffed, non tunnelled catheters should be used for less than one week. Tunnelled catheters should be placed for those who require dialysis for longer than one week [45]. More recently, a noncuffed, non-tunnelled triple-lumen dialysis catheter has been developed. The purpose for third lumen is blood drawing and intravenous administration of drugs and fluid. In a multicenter, prospective study, blood flow rates and infectious complications were similar

Taking patient factors into consideration, such as life expectancy, comorbidities, the status of the venous and arterial vascular system, is very important in order to prescribe the appropriate access. Other factors are determined by the type of access itself, such as arteriovenous fistula (AVF), arteriovenous graft (AVG), or TC which have a different effect on circulatory system. Also, the duration of their functionality and the risk for infection and thrombosis are important factors to consider. Each type of surgical anastomosis has advantages and disadvantages [50]. In 2002 the American Association for Vascular Surgery and the Society for Vascular Surgery published reporting standards according to which three essential components of VA should be mentioned: conduit (autogenous, prosthetic),

An AVF is the preferred type of vascular access; it has the lowest complication rates for

First type when artery and vein are connected in their natural position, either with a

 Second type, where a vein is moved to connect to an artery in end-to-side fashion to either bridge a larger anatomical distance, or to bring the vein to the surface where it is accessible for cannulation and requires a tunnel to position the vein in its new location.

thrombosis (one-sixth of AVGs) and infection (one-tenth of AVGs) [52, 53].

avoided because of the high incidence of vein stenosis and thrombosis.

Infectious complications are the principal reason for catheter removal.

location and configuration (strait, looped, direct, etc.) [51].

side-to-side or a side-artery-to-vein-end anastomosis.

[43, 44].

with double lumen catheter [49].

**3.2 Permanent vascular access** 

**3.2.1 Arteriovenous fistula** 

There are 3 types of AVFs:

Fig. 1. Non cuffed internal jugular double lumen catheter

Fig. 2. Cuffed tunnelled internal jugular double lumen catheter

Fig. 3. Permanent cuffed jugular catheter

Fig. 4. Acute non-cuffed jugular catheter

Fig. 5. Femoral non-cuffed catheter

Fig. 1. Non cuffed internal jugular double lumen catheter

Fig. 2. Cuffed tunnelled internal jugular double lumen catheter

Fig. 3. Permanent cuffed jugular catheter

Fig. 4. Acute non-cuffed jugular catheter

Fig. 5. Femoral non-cuffed catheter

Central veins such as jugular, subclavian or femoral, can be used as insertion routes of these catheters [42]. The femoral artery can be used as an access central vein when all other central veins have been excluded. For their insertion a modified Seldinger guide wire technique is used. In order to minimize immediate insertion complications, image guided assistance is recommended. Non-cuffed catheters are also suitable for use at the bedside of the patient [43, 44].

The 2006 National Kidney Foundation Dialysis Outcomes Quality Initiative (K/DOQI) guidelines recommend, after internal jugular or subclavian vein insertion, identifying radiographically any potential complications and confirming tip placement prior to either anticoagulation or catheter use [45]. Nowadays, the subclavian catheters should be generally avoided because of the high incidence of vein stenosis and thrombosis.

The maximum blood flow with this class of catheters is usually blood pump speeds of 300 mL/min, with an actual blood flow of 250 mL/min or less [46, 47]. Femoral catheters have to be at least 18 to 25 cm in length in order to have lower recirculation. The routine use-life of these catheters varies depending on the site of insertion. Generally speaking, internal jugular catheters are suitable for two to three weeks of use, while femoral catheters are usually used for a single treatment (ambulatory patients) or for three to seven days in bed bound patients [48]. However, the KDOQI guidelines suggest that non-cuffed, non tunnelled catheters should be used for less than one week. Tunnelled catheters should be placed for those who require dialysis for longer than one week [45]. More recently, a noncuffed, non-tunnelled triple-lumen dialysis catheter has been developed. The purpose for third lumen is blood drawing and intravenous administration of drugs and fluid. In a multicenter, prospective study, blood flow rates and infectious complications were similar with double lumen catheter [49].

Infectious complications are the principal reason for catheter removal.

#### **3.2 Permanent vascular access**

Taking patient factors into consideration, such as life expectancy, comorbidities, the status of the venous and arterial vascular system, is very important in order to prescribe the appropriate access. Other factors are determined by the type of access itself, such as arteriovenous fistula (AVF), arteriovenous graft (AVG), or TC which have a different effect on circulatory system. Also, the duration of their functionality and the risk for infection and thrombosis are important factors to consider. Each type of surgical anastomosis has advantages and disadvantages [50]. In 2002 the American Association for Vascular Surgery and the Society for Vascular Surgery published reporting standards according to which three essential components of VA should be mentioned: conduit (autogenous, prosthetic), location and configuration (strait, looped, direct, etc.) [51].

#### **3.2.1 Arteriovenous fistula**

An AVF is the preferred type of vascular access; it has the lowest complication rates for thrombosis (one-sixth of AVGs) and infection (one-tenth of AVGs) [52, 53].

There are 3 types of AVFs:


Vascular Access for Hemodialysis 51

Ultrasound must be done before surgical implantation because it can provide information for maximal surgical success by mapping arteries and veins; e.g. a preoperative arterial lumen diameter >2 mm is associated with successful fistula maturation [56], while a diameter of <1.6 mm predicts failure of the procedure [58]. Kidney Disease Outcomes Quality Initiative (KDOQI) Vascular Access guidelines, suggest that a working AVF should have a blood flow >600 mL/min, a diameter >0.6 cm, and be at a depth of 0.6 cm (between 0.5 and 1.0 cm) from the surface, 6 weeks after its creation. In fistulas that are successfully maturing, flow increases rapidly post-surgery, from baseline values of 30–50 mL/min to 200–800 mL/min within 1 week, generally reaching flows >480 mL/min at 8 weeks [59, 60]. The AVFs must be evaluated 4–6 weeks after placement, and experienced examiners (e.g.,

AVGs (Figure 10-12) were the most commonly used type of dialysis access in the U.S. [62]. However, they do not last as long as AVFs and they have higher rates of infection and thrombosis [52]. Grafts present a second choice of VA when AVF is not able to be performed because of vascular problems. They can be placed in the forearm, the upper arm, and the thigh, and can have a straight, curved or loop configuration. They may offer a large surface area for cannulation. AVGs can be cannulated about 2-3 weeks after placement, although there are studies suggesting that immediate assessment after placement for PTFE AVGs is possible [63, 64]. This interval is needed in order to allow the surrounding tissue to adhere to the PTFE conduit, to reduce the postsurgical oedema and the risk for local complications

dialysis nurses) can identify non-maturing fistulas with 80% accuracy [61].

**3.2.2 Arteriovenous graft** 

Fig. 10. Upper arm AVG

Fig. 11. Looped Forearm AVG

Fig. 12. Straight femoral AVG

such as perigraft hematoma and seroma [65].

 Third type where a vein is removed from its anatomical location and is connected to an artery and vein in end-to-end fashion.

Both second and third types require the formation of a tunnel [54] (Figure 6-9). End-to-end anastomoses are now rarely performed, since the complete disruption of the artery imposes a risk for peripheral ischemia and thrombosis. The most common surgical technique today is the side-to-end anastomosis. However, technical problems such as cutting the end of the vein in an oblique angle may create functional problems due to stenosis. An anastomosis more proximal in the arterial system should be smaller to prevent steal symptoms and limit maximal fistula flow, with the inherent complication of ischemic steal or heart failure [54]. Arteriovenous fistula creation is often performed under local anaesthesia, with low morbidity and requires time for maturation. Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) indicate that AVFs should mature at least 14 days before use [55]. Fistula size and flow increase over time of 8–12 weeks and the initial blood flow rates has a range of 200–300 mL/min.

Fig. 6. Forearm AVF

Fig. 7. Side to side forearm AVF

Fig. 8. End to end forearm AVF

Fig. 9. Side to end forearm AVF

Placement of AVFs should be initiated when the patient reaches CKD stage 4, or within 1 year of the anticipated start of dialysis. A physical examination should document blood pressure differences between the upper extremities[56] and an Allen test should be performed as the lack of a well-developed palmar arch predispose for vascular steal symptoms in case the dominant artery is used for the VA creation [57].

Third type where a vein is removed from its anatomical location and is connected to an

Both second and third types require the formation of a tunnel [54] (Figure 6-9). End-to-end anastomoses are now rarely performed, since the complete disruption of the artery imposes a risk for peripheral ischemia and thrombosis. The most common surgical technique today is the side-to-end anastomosis. However, technical problems such as cutting the end of the vein in an oblique angle may create functional problems due to stenosis. An anastomosis more proximal in the arterial system should be smaller to prevent steal symptoms and limit maximal fistula flow, with the inherent complication of ischemic steal or heart failure [54]. Arteriovenous fistula creation is often performed under local anaesthesia, with low morbidity and requires time for maturation. Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) indicate that AVFs should mature at least 14 days before use [55]. Fistula size and flow increase over time of 8–12 weeks and the initial blood flow rates has a

Placement of AVFs should be initiated when the patient reaches CKD stage 4, or within 1 year of the anticipated start of dialysis. A physical examination should document blood pressure differences between the upper extremities[56] and an Allen test should be performed as the lack of a well-developed palmar arch predispose for vascular steal

symptoms in case the dominant artery is used for the VA creation [57].

artery and vein in end-to-end fashion.

range of 200–300 mL/min.

Fig. 6. Forearm AVF

Fig. 7. Side to side forearm AVF

Fig. 8. End to end forearm AVF

Fig. 9. Side to end forearm AVF

Ultrasound must be done before surgical implantation because it can provide information for maximal surgical success by mapping arteries and veins; e.g. a preoperative arterial lumen diameter >2 mm is associated with successful fistula maturation [56], while a diameter of <1.6 mm predicts failure of the procedure [58]. Kidney Disease Outcomes Quality Initiative (KDOQI) Vascular Access guidelines, suggest that a working AVF should have a blood flow >600 mL/min, a diameter >0.6 cm, and be at a depth of 0.6 cm (between 0.5 and 1.0 cm) from the surface, 6 weeks after its creation. In fistulas that are successfully maturing, flow increases rapidly post-surgery, from baseline values of 30–50 mL/min to 200–800 mL/min within 1 week, generally reaching flows >480 mL/min at 8 weeks [59, 60]. The AVFs must be evaluated 4–6 weeks after placement, and experienced examiners (e.g., dialysis nurses) can identify non-maturing fistulas with 80% accuracy [61].
