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A three-step approach to conversion of prevalent catheter-dependent hemodialysis patients to arteriovenous access.

Introduction

The arteriovenous fistula (AVF) is universally accepted as the optimal vascular access for chronic HD patients (Mendelssohn et al., 2006b). The second best is the arteriovenous graft (AVG), while the least desirable is the central venous catheter (CVC) (Astor et al., 2005; Hemodialysis Clinical Practice Guidelines for the Canadian Society of Nephrology, 2006; NKF-KDOQI, 2006; Polkinghorne, McDonald, Atkins, & Kerr, 2004). The AVF is associated with decreased mortality and morbidity, low complication and procedure rates, and improved longterm survival when compared to an AVG and CVC (Astor et al., 2005; Dhingra, Young, Hulbert-Shearon, Leavey, & Port, 2001; Lok, 2007, NKF-KDOQI, 2006; Pastan, Soucie, & McClellan, 2002; Pisoni et al., 2002; Polkinghorne et al., 2004; Xue, Dahl, Ebben, & Collins, 2003).

Mokrzycki and Lok (2010) suggest that initiating and maintaining HD with a CVC is considered as a suboptimal start from the patient care perspective and long-term costs of CVC use.

The Canadian experience

Despite their known association with numerous detrimental outcomes and similar Canadian guidelines for vascular access, Canadian chronic HD patients often rely on a CVC for vascular access (Ethier et al., 2008; Hemodialysis Clinical Practice Guidelines for the Canadian Society of Nephrology, 2006; Mendelssohn, Ethier, Arrington, Pisoni, & Port, 2006a; Mendelssohn et al., 2006b). In fact, during the Dialysis Outcomes and Practice Patterns Study (DOPPS) II (2002-2004), 33% of all prevalent patients and 70% of incident patients in Canadian centres were using a CVC for chronic HD, and only 26% initiated with a functioning AV access, despite 79% of patients reporting to having seen a nephrologist more than four months before reaching end stage renal disease (ESRD) (Mendelssohn, Ethier, Arrington, Pisoni, & Port, 2006a; Mendelssohn et al., 2006b). More recent data suggest that by 2008, this had worsened to 51% CVC (Canadian Institute of Health Information, 2008) for prevalent patients. In comparison, 48% of patients in the United States and 79% of patients in Europe who saw a nephrologist for more than 30 days used an AV access for their first HD (Pisoni et al., 2002).

Other factors that contribute to the high prevalence of CVC use in Canada in patients on HD include: resource limitations, such as fewer vascular surgeons per 100 HD patients, as compared to the United States or Europe; increased wait times for evaluation and surgery; less time devoted to vascular access per patient, and late referrals to vascular surgeons (Mendelssohn et al., 2006b). According to data from the DOPPS II study, the typical time from referral to a vascular surgeon until permanent vascular access creation is substantially longer in Canada (61.7 days), than in the United States (16 days) or in Europe (29.4 days). The investigators suggest that longer delay time to creation of AV access and higher catheter use in Canada may be a consequence of fewer vascular surgeons in Canada (2.9) compared with the United States (8.1) and Europe (4.6).

Furthermore, the number of hours per week devoted to vascular access-related surgery is substantially lower in Canada (0.027 hours), as compared with the United States (0.082 hours) and Europe (0.059 hours).

According to Lok (2007), a Canadian nephrologist, creating fistulas may not be the critical challenge, but rather achieving 65% functioning fistulas in today's dialysis patient population. Studies suggest that an estimated 55% to 60% of AVFs are underdeveloped and not usable for HD, and that maturation often takes five months or longer (Dember et al., 2008; Lok et al., 2006; Biuckians, Scott, Meier, Panneton, & Glickman, 2008; Feldman et al., 2003). An increase in primary failure rates in incident and prevalent patients may also contribute to the high use of CVC for vascular access and associated catheter-related complications (Allon & Lok, 2010; Lee, Barker, & Allon, 2005; Ravani et al., 2004).

Graham, Hiremath, Magner, Knoll, and Burns (2008) examined the prevalence of CVC use in Canadian patients and found barriers to conversion included unsuitable vessels, patient comorbidities, system/resource limitations, and patient refusal.

According to Lok (2007), the changing demographics of incident ESRD patients caused by the rising rates of diabetes, along with an increased number of patients over the age of 75, has led to a patient population with enough comorbidities to make CVC use an easier alternative for patients and HD nurses for initiation of dialysis. Furthermore, female gender, obesity, peripheral vascular disease (PVD), age older than 65 years, and preference of the staff in the dialysis unit, are all independently associated with increased use of CVC.

Literature review

The National Kidney Foundation Kidney Dialysis Outcomes Quality Initiative (NKF-KDOQI) guidelines for vascular access discourages the use of CVC for chronic HD and recommends that less than 10% of chronic HD patients should be maintained on tunnelled CVC. Furthermore, the NKFKDOQI guidelines recommend that 50% of incident patients and 40% of prevalent patients use an AVF for vascular access (NKF-KDOQI, 2006). The primary goal of the United States multi-stakeholder Fistula First Initiative was recently revised, and now recommends that 65% of appropriate patients use an AVF for vascular access (Fistula First, 2010).

Pisoni, Young, and Combe (2005) reported from DOPPS data a 16% excess risk of death for every 20% increase in catheters when compared to fistulas. Furthermore, they reported a reduction in mortality risk by decreasing catheter use to the NKF-KDOQI target in Canada and the United States, while keeping graft use constant. More recent studies also suggest that conversion from a CVC to an AV access is associated with lower mortality among incident patients (Bradbury et al., 2009), and incident and prevalent patients (Allon et al., 2006; Lacson, Wang, Lazarus, & Hakim, 2009).

Patients with a CVC have been shown to have higher rates of hospitalization, more incidence of local and systemic infections, suboptimal blood flow (resulting in reduced clearance), and poor quality of life (Allon et al., 2003; Astor et al., 2005; Churchill et al., 1992; Dhingra et al., 2001; Lopes et al., 2007; Nassar & Ayus, 2001; Pastan et al., 2002; Polkinghorne et al., 2004).

In addition, CVCs have been associated with development of central venous stenosis and thrombosis, access failure, and increased costs (MacRae, Ahmed, Johnson, Levin, & Kiaii, 2005; Manns et al., 2005; NKF-KDOQI, 2006; Yuan et al., 2007). In fact, it has been reported that 40% of patients who undergo venography have central venous stenosis, which may preclude later AVF creation or hamper maturation (MacRae et al., 2005; Yuan et al., 2007).

Furthermore, it is well documented that patients who have had a CVC placed before AVF creation have reduced fistula survival, as compared to patients who did not have a CVC (Pisoni et al., 2002; Hakim & Himmelfarb, 1998; Ravani et al., 2005). Currently, the primary failure rates for fistulas range between 20% and 70% with a one-year primary patency rate of 40% to 70% (Ackad et al., 2005; Allon, & Robbin, 2002; Dixon, Novak, & Fangman, 2002; Gibson et al., 2001). Ferring, Claridge, Smith and Wilmink (2010) report that routine preoperative ultrasound mapping improves patency and AVF outcomes. These findings support National and European guidelines for routine preoperative ultrasound mapping (NKFKDOQI, 2006; Tordoir et al., 2007).

One possible barrier to AV access creation is the nephrologists' attitudes and perceptions about referral and patient suitability for vascular access creation based on patient characteristics (diabetes, obesity, age, and failed prior vascular access). According to the quality initiative report of 2001, failure of nephrologists to act as vascular access coordinators was found to be the topmost barrier to creation of AV fistulas (Northwest Renal Network, 2010).

Graham et al. (2008) surveyed Canadian nephrologists and found that 100% agreed that the AVF was the optimal access for HD, 100% disagreed that female sex was a contraindication for referral for AVF creation, and only 24% considered age when referring a patient for AV access. Furthermore, according to Mendelssohn et al. (2006b), 94% of nephrologists in Canada report that the preferred type of access for patients expected to initiate dialysis in two or more months was the AV fistula. This figure was higher in the United States (98%) and in Europe (99%).

Key modifiable factors that may affect patient's resistance and conversion of catheter-dependent patients to AV access creation include patient choice and ultimate refusal, patient preference, patient satisfaction, cannulation-related complications such as pain, disfigurement, bleeding, fear of needles, and surgical fatigue (Asif et al., 2005; Bay, Van Cleef, & Owens, 1998; Lee, Barker, & Allon, 2005; Lok, 2007; Quinn et al., 2008; Yuan et al., 2007).

Yuan et al. (2007) examined CVC use and compared the patient perspective with that of vascular access coordinators (VAC). They found that their perspectives differed with respect to the advantages and disadvantages of different vascular accesses, suggesting a knowledge gap between the care provider and patient. For example, 25% of patients reported that they had exhausted access sites, whereas the VAC noted this to be the case in only 5% of patients.

Conversion to more optimal forms of vascular access requires an organized approach utilizing a dedicated team including nephrologists, vascular access coordinators, HD nurses, vascular surgeons, and interventional radiologists, and requires the use of a wide range of surgical and radiological techniques and salvage procedures (Asif et al., 2005; Lok, 2007; Mendelssohn et al., 2006b).

Asif et al. (2005) examined conversion of catheter-dependent patients to vascular access and reported that the basilic vein in the upper arm was commonly patent, even in patients with multiple failed vascular accesses. The authors recommend always assessing for patency of the basilic vein prior to consigning a patient to permanent dependence on a percutaneous vascular catheter. These findings are consistent with other research, where the basilic vein was patent in more than 95% of catheter-dependent patients (Humphries, Colborn, & Wynn, 1999; Matsuura et al., 1998), and thereby should be considered as a strategy for increasing fistulas when surgical expertise is available.

Summary

The detrimental risks to health for patients on HD using a CVC for permanent access have been well documented. However, conversion of prevalent catheter-dependent patients to more optimal forms of vascular access is challenging, but has not been so well studied.

Methods

Main study objectives

The primary objective of the conversion project was to achieve a 50% conversion rate of suitable patients from CVCs to AVFs or AVGs. In October 2006, we reviewed all chronic incentre HD patients at our centre receiving dialysis with a CVC to determine suitability for AV access creation (AVF or AVG).

Study setting, design, and population

The Humber River Regional Hospital (HRRH) department of nephrology is a community-based regional program in north-west Toronto, Ontario. The in-centre HD unit currently has 53 stations and a maximum of 318 patients. An additional 100 patients are on home-based or self-care HD. We undertook a case-crossover evaluation of the efficacy of a three-step strategy to convert prevalent in-centre HD patients with CVCs to either AVF or AVG.

Ethics and patient consent procedures

The CVC conversion protocol was considered a continuous quality improvement project. Therefore, the project did not go through a research ethics review process and formal informed patient consent was not obtained. Furthermore, patient consent was implicit, based on patient's willingness to engage in discussion, read relevant materials, and willingness to undergo further evaluation or procedures. Written informed consent was obtained for endovascular and surgical procedures, following usual hospital procedures.

Baseline vascular access planning and referral practice

Patients in our CKD clinic are seen by a multidisciplinary renal team consisting of primary nephrologists, pharmacists, dietitians, nurse clinicians and social workers prior to initiating dialysis. The average time from referral to the vascular surgeon to creation of AV access at our centre is seven weeks (49 days), which is shorter than the Canadian average of 61.7 days (DOPPS II). Our vascular surgeon devotes approximately six hours per week to AV access surgery, and performs an average of 10 access surgeries per month.

Yet, despite a structured team approach to patient care, many incident patients in our centre still initiate HD with a CVC. At our centre, we consider a patient to have a suboptimal start if he/she fails to initiate dialysis with the modality of choice, initiates dialysis acutely with a CVC, or fails to initiate HD with a functioning AVF or AVG.

Prior to the conversion project, the process for assessing prevalent catheter-dependent patients for AV access creation was not formalized and did not include standardized written material or discussions with patients, and patients were not routinely scheduled for preoperative vascular mapping. Generally, patients were only approached for AV access creation at initiation of HD, and patients who refused AV access or whose AV access failed were not approached again.

Vascular access conversion protocol

In step one, all prevalent in-centre patients with a CVC were entered into the project database (n=108) (see Table 1 flow chart with project results). Patients were considered eligible if they had a CVC and been on dialysis for more than 90 days. Exclusion criteria included dementia, inability to provide informed consent (implicit or written), patients who were unable to understand written materials (translation was allowed), patients with terminal illness or life-expectancy less than six months, and patients awaiting living-related transplant. Based on these criteria, six patients were excluded, leaving an eligible patient pool of 102 patients.

The clinical nurse specialist and nephrologists assessed patients' medical suitability for AV access creation based on past medical history and access history. Suitability was defined as patients deemed to be medically suitable for AV access creation. A checklist (Appendix B) with indications for catheter use was completed by the clinical nurse specialist for all catheter-dependent patients, and the checklist was placed in the patient's chart. The patients were also asked to complete a similar checklist (Appendix A) with their perspective of why they had a catheter, in order to determine degree of concordance with staff. Patients deemed medically unsuitable for AV access creation based on the criteria found in the checklist (Appendix B) were excluded from the conversion project. The cohort of remaining patients was considered medically suitable for conversion.

In step two, all medically suitable patients were given a patient newsletter and a one-page information sheet (Appendix C). The information sheet was intended to be similar to the popular fable by Hans Christian Andersen, "The Emperor's New Clothes" and was adapted for use for our project. The fable included a picture (reproduced with permission by Dr. Raymond Hakim) of an emperor peeking around a tree with a dual lumen catheter hanging from his chest, and detailed information about the risks of long-term catheter use.

The fable (Appendix C) was used to illustrate to patients, family members and staff that although patients may "fall in love" with their catheter, as they see that patients are attached to the dialysis machine more quickly and painlessly and they don't have large bumps on their arms that patients with fistulas do, catheters are, in fact, associated with poorer patient outcomes, including increased morbidity, mortality, infection, hospitalization, and death. Descriptive information was gathered through discussions with patients. Information was not captured systematically and there was no direct comparison with a control group.

During the entire process, discussions about vascular access between patients, family members, and the health care team were encouraged. HD nurses were integral to the process, particularly with their ability to reinforce education and their close relationship with patients, which places them in a key position to engage patients and families in discussions about vascular access. Patients with CVCs were also encouraged to speak with patients who have fistulas and patients who have successfully converted to AV access and had their CVCs removed.

All suitable patients who agreed to conversion were scheduled for preoperative bilateral arterial and venous arm mapping and referred to see the vascular surgeon for assessment of surgical suitability for AV access creation. The vascular surgeon determined surgical suitability based on past access history, medical history, preoperative vascular arm mapping, and clinical assessment and portable ultrasound assessment of superficial veins, in collaboration with the clinical nurse specialist.

In step three, the clinical nurse specialist and nephrologists spoke with all suitable patients who refused AV access creation. Patients who refused conversion were asked to sign a waiver (Appendix D), indicating that they had chosen to continue with a CVC; with full understanding of the potential consequences, and that their decision was "against medical advice". The signed waiver was placed in the patient's chart along with the completed checklist with indications for catheter use.

Results

At the start of the project in October 2006, 284 prevalent in-centre HD patients had the following vascular access types: 38% of patients with CVC, 4% with AVG, and 58% with AVF. Thus, 38% of patients with CVC (n=108) were deemed potentially eligible for AV access creation (AVF or AVG).

Table 2 (initial cohort column) shows the demographic data, baseline patient characteristics, and co-morbidities of catheter-dependent patients in the project. The average age was 70 years old, 53% were female, 48% had diabetes, and 24% had previously been on peritoneal dialysis. The average length of time the CVC was in place was 49 months (range 17 days to 134 months), and the average number of prior surgical vascular access creation attempts was two (range 0-9). Patients with CVCs in place for less than 90 days included patients with failed fistulas during the project period, patients who were deemed no longer suitable for peritoneal dialysis and converted to HD, and patients with functioning AV access awaiting removal of CVC.

Comorbidities include 21% of patients with cerebrovascular disease, which is defined by the World Health Organization (as cited in Truelsen, Begg, & Mathers, 2000) as documented cerebral vascular accident or transient ischemic attack; 20% with peripheral vascular disease (surgical bypass, intermittent claudication or previous gangrene); 44% with heart disease (previous myocardial infarction, cardiac surgery or angioplasty), and 93% with hypertension (pre-dialysis systolic BP of [greater than]140 mmHg, or diastolic BP [greater than] 90 mmHg).

Table 1. Flowchart with project results

n = 108                                 6 pts excluded

n = 102

Step 1: Assessment of Medical Suitabilty for AV access creation

Medically suitable: 65pts/64%           Medically unsuitable:
                                        37pts/36%

Step 2: Fable given to all patients deemed medically suitables (65 pts)

Agree to conversion: 47 pts             Refuse conversion: 18 pts

In conversion process: 26 pts           Unsuitable: 5 pts

Successfully converted: 22 pts Primary  Refuse conversion after
failure: 3 pts (2 deemed surgically     vascular assessment: 9
unsuitable (primary failure) and 1      pts
awaiting assessment) Under review for
medical stability: 1 pt

                                        Exit from cohort:
                                        (2/transfer/3
                                        transplanted/3 died) 7
                                        pts

                                        Surgically unsuitable
                                        (primary failure): 2 pts

Step 3: Waiver given to medically suitable patients who refused
conversion (27 pts)

Signed waiver: 19 pts (70%)             Refused to sign waiver: 8
                                        pts (30%)

Patient characteristics are presented by study phase in Table 2 (converted, non-converted, and unsuitable columns); suitable patients who agreed to conversion (converted), patients who refused conversion (non-converted), and patients deemed unsuitable for conversion (unsuitable). Unsuitability was further divided into medical and surgical unsuitability (Table 3). When compared to the other two groups, patients who agreed to conversion (converted) tended to be younger, had the highest rates of diabetes and hypertension, length of time catheter had been in place was shorter (mean of 30 months), and had less cerebrovascular disease and heart disease. Patients who refused conversion were less likely to have been on peritoneal dialysis, length of time catheter had been in place was longer (mean of 64 months), had fewer prior AV access attempts, and the highest rates of heart disease. Patients deemed unsuitable for AV access creation were older, more were female than male, and they had the highest rate of cerebrovascular disease and peripheral vascular disease. Similar to study by Lok (2007), we found that CVC use was highest among patients who were older, diabetic, female, and had PVD.

Of the 65 patients who were deemed medically suitable for AV access, 35 patients agreed to conversion and 30 patients refused conversion. Of the 35 patients who agreed to conversion, 22 (63%) had been followed in CKD clinic for four months or more and 13 (37%) patients initiated dialysis acutely. Of the 30 patients who refused conversion, 17 (57%) had been followed in CKD clinic for four months or more and 13 (43%) initiated dialysis acutely.

The difference between the group who agreed to conversion and the group who refused conversion was not statistically significant (p=0.62 by Chi-square test), thereby suggesting that there are factors other than attending the CKD clinic that affect a patient's decision to convert to AV access.

Information obtained from the checklist (Appendix A) on patients' perspective of why they wanted to remain with their catheter included being able to get on and off the dialysis machine more quickly, no needles or pain, no large bumps on their arms, no waiting after dialysis to hold needle sites, their lines are working fine, and the catheter is their choice.

In discussion with patients about vascular access, patients reported that patients with fistulas have large bumps on their arms, and have cannulation-related complications, such as difficulty with placement of needles, pain, bruising and swelling from the needles, and they sometimes miss their transportation due to bleeding after dialysis. Patients who converted to a fistula and had their catheter removed report that they can swim and shower freely, they no longer worry about getting an infection, and having a tube hanging from their chest reminded them that they were sick.

In step one, 65/102 patients were deemed medically suitable for AV access creation and 37/102 patients were deemed medically unsuitable. In step two, 18/65 patients initially deemed medically suitable for AV access creation refused conversion and preoperative vascular assessment, and nine patients refused conversion after preoperative vascular assessment. An additional three patients were deemed secondarily medically unsuitable because of changes in their overall medical condition, two patients were deemed surgically unsuitable after assessment, two patients were transplanted, three patients were transferred, and two patients died (n=26).

Table 2. Initial demographic characteristics and comorbidities

Co-morbidities and demographics             Initial  Converted
                                             cohort

                                               n=95       n=26

Diabetes mellitus                               48%        54%

Cerebrovascular disease (documented             21%         4%
cerebral vascular accident or transient
ischemic attack)

Peripheral vascular disease (surgical           20%        19%
bypass, intermittent claudication, or
previous gangrene)

Heart disease (previous myocardial              44%        35%
infarction, cardiac surgery or
angioplasty)

Hypertension (pre-dialysis systolic BP of       93%        96%
[greater than]140 mmHg, or diastolic BP
[greater than] 90 mmHg)

Previous peritoneal dialysis                    24%        35%

Average age (years)                              70         66

Gender male                                     47%        58%

Average months CVC in situ                       49         29

Time catheter in situ (shortest/longest)   0.57-134       2-82
                                             months     months

Average attempts of AV access creation            2          2
(0-9)

Co-morbidities and demographics      Non-converted     Unsuitable
                                                         (medical

                                              n=27  and surgical)
                                                             n=42

Diabetes mellitus                              52%            43%

Cerebrovascular disease (documented            26%            33%
cerebral vascular accident or
transient ischemic attack)

Peripheral vascular disease                    19%            21%
(surgical bypass, intermittent
claudication, or previous gangrene)

Heart disease (previous myocardial             52%            45%
infarction, cardiac surgery or
angioplasty)

Hypertension (pre-dialysis systolic            89%            93%
BP of [greater than]140 mmHg, or
diastolic BP [greater than] 90
mmHg)

Previous peritoneal dialysis                   19%            21%

Average age (years)                             71             74

Gender male                                    48%            40%

Average months CVC in situ                      64             54

Time catheter in situ                       30-134          2-128
(shortest/longest)                          months         months

Average attempts of AV access                    1              2
creation (0-9)

Legend: Arteriovenous (AV); Blood pressure (BP); Central venous
catheter (CVC); Millimetres of mercury (mmHg)

As of December 2010, 25/26 patients have undergone surgery for AV access creation. AV access creations as a result of the conversion project includes 13 radiocephalic fistulas, eight brachiocephalic fistulas, and four transposed basilic vein fistulas (Table 4). No suitable patients received an AVG.

Of the 25 patients who have had surgery, 22 patients have successfully converted to AV access and had their CVC removed, two patients experienced primary failure and have been deemed surgically unsuitable for further AV access surgery, one patient experienced primary failure and is undergoing further assessment for AV access creation, and one patient is still in the process of being assessed for AV access (n=24). The patient who experienced primary failure is being assessed for surgical suitability for a basilic vein transposition procedure (two previous AV access failures and a history of central stenosis), and the second patient is being assessed for a transposed basilic vein fistula, pending investigation of hypercoagulability (two previous AV access failures).

In step three, of the 27 suitable patients who refused conversion, 19 (70%) signed the waiver and eight (30%) refused to sign the waiver. None of the patients agreed to conversion after being presented with the waiver. Patients who agreed to sign the waiver stated, "If I sign the paper, then I won't be asked again about getting a fistula," and "Signing the paper makes it official because the paper is put into my chart". Patients who refused to sign the waiver stated, "I don't want my signature on a piece of paper" and "I don't want to have something put into my chart" (Table 1 flow chart with project results).

Overall, 22 patients with CVCs were successfully converted to an AV access at the end of the follow-up, achieving p[less than]0.001 by McNemar's Test, comparing the number of conversion from CVC to an AV access with the number of conversions from AV access to CVC. No patients voluntarily switched from AV access to a CVC during follow-up. If the number of AV access failures during the project period is considered (n=12), the effect of the conversion protocol would have been attenuated, and not statistically significant. However, without the 22 converted patients, the overall number of AV accesses in our program would have declined significantly (p[less than]0.001 by McNemar's Test).

Our three-step approach has resulted in conversion of 41.5% of prevalent catheter-dependent patients to AV access. This rate would increase to 45% if the two remaining patients in the conversion process successfully converted. Yet, despite a high conversion rate, the percentage of in-centre point-prevalent catheter-dependent patient's increased during the project period from 38% in October 2006 to 46% in December 2010. However, if the conversion project had not been implemented, our prevalent CVC rate would be 53%.

An important factor affecting the increase in percentage of point prevalence is that 70% of incident patients in our centre initiated HD with a CVC during the project period, despite a structured multidisciplinary team approach to patient care.

Discussion

The primary objective of our project was achieved. We were successful in converting many suitable patients to an AV access with an ultimate goal of decreasing CVC rates and increasing AV access rates. Although our three-step conversion strategy was successful in converting 41.5% of suitable CVC-dependent patients to an AV access, the percentage of in-centre point-prevalent catheter-dependent patients increased during the project period from 38% in October 2006 to 46% in December 2010.

Factors that likely contributed to the increase in point-prevalence CVC rates during the project period include a high rate of patient refusal, a high rate of patients deemed to be medically unsuitable, AV access failure during the project period, failed peritoneal dialysis and conversion to HD, failed transplant, catheter-dependent patients transferring from other centres, and most common was a failure to create AV access among incident HD patients who were followed in our centre through the late stages of chronic kidney disease (CKD).

Results of our project suggest there is a critical need to identify barriers to timely vascular access creation and to develop strategies aimed at reducing catheter use that is expected to result in improvement in patient care.

Barriers to conversion

Asif et al. (2005) reported that patients denied having received information about types of vascular access, their associated complications, and increased morbidity and mortality, and that 37% of patients refused vascular mapping or AV access creation despite being informed of the risks of remaining with a CVC. Descriptive information obtained from patients who were presented with the fable (Appendix C) included reports that they were not previously informed about the many problems associated with catheters and were not told that fistulas were better. Patients with previously failed fistulas stated that they were told they couldn't have another fistula.

Patient refusal

Asif et al. (2005) and Lee, Barker and Allon (2005) report that the longer the catheter was in place, the less likely it was that the patient would agree to conversion. Furthermore, Asif et al. (2005) and Xi et al. (2010) report refusal rates of 37% and 77% respectively, despite aggressive educational efforts. Similarly in our study, we found that there was a high refusal rate (53%), and patients who refused conversion (non-converted) had their catheter in place longer (134 months), with an average time of 49 months (just more than four years).

Table 3. Medical and surgical unsuitability for arteriovenous access
creation

Total unsuitability              Medical       Surgical
                              unsuitability  unsuitability

Step 1                              37            n/a
Step 2                              3             4 *
Total unsuitability n = 44 *      n = 40         n = 4

* Two patients experienced primary failure and were deemed surgically
unsuitable for any further AV access surgery

Table 4. Arteriovenous access surgeries as result of the conversion
project

AV access types                  AV access creation n=25

Radiocephalic fistula                      13
Brachiocephalic fistula                     8
Arteriovenous graft                         0
Transposed basilic vein fistula             4

In fact, in our study, the problem of refusal of conversion by suitable patients was as common as consent to convert. In terms of effort and resources, detailed work-up and time-consuming interactions by a clinical nurse specialist, nephrologists, HD nurses, and vascular surgeons identified 95 patients eligible for conversion, but led to refusal by 27 and surgery in only 25 patients. As a result, roughly half of all catheter-dependent patients were unsuitable for conversion, one quarter were suitable but refused to convert, and one quarter were suitable and willing.

Nephrologist attitude and informed refusal

Rehman et al. (2009) suggest that if we are to reduce high catheter rates, nephrologists need to develop the conviction that CVCs are not a safe-long-term vascular access option for their patients who, indeed, may be good candidates for an AVF or AVG. The authors recommend that when catheter-dependent patients who are deemed to be suitable candidates for AV access creation continue to refuse, the nephrologist may want to require informed refusal, and give suitable patients a printed statement listing the numerous complications of CVC use, including the nephrologist's strong recommendation against long-term CVC use. They suggest that patients could be asked to read the statement, acknowledge its content, and sign at the bottom that he or she continues to choose to receive their dialysis with a catheter. Furthermore, Hakim and Himmelfarb (2009) suggest that a proactive process needs to be considered, which includes an informed non-consent for catheter-dependent patients who decline permanent AV access creation.

At our centre, we implemented a similar approach and requested that patients who refused AV access sign a waiver, although this did not prove to be effective in converting our catheter-dependent patients to better forms of vascular access. Initially, we estimated that 50% of patients who were asked to sign the waiver would have agreed to conversion, when, in fact, no patient agreed to conversion when presented the waiver.

Watson (2009) suggests that nephrology providers need to move away from the idea that CVCs are "permanent" catheters, which, in turn, makes patients more reluctant to see them as not permanent. "To patients, nurses and doctors alike, the concept of a permanent central venous catheter for HD is appealing. For patients, these catheters are virtually pain-free after the initial insertion, and for HD nurses, they are easy to use, often saving time and the inconvenience of needling" (p. 39).

Lee et al. (2005) report that "it is possible that some patients with multiple missed surgery appointments have no intention of proceeding with access surgery, but are unwilling to explicitly state their position" (p. 507). Similar to our experience, several patients agreed to venous mapping and then refused conversion, and one patient is still in the process of conversion after four years, yet has neither expressed unwillingness to convert, nor refused conversion.

Patient unsuitability and fistula survival

Overall, 44/95 (46%) patients were deemed unsuitable for conversion in our study. It is possible that our criteria for determining medical suitability were too strict and that another centre could have created a larger pool of suitable patients.

Graham et al. (2008) examined the prevalence of CVC use in patients on HD at one centre in Canada and found that an even larger percentage of patients (68.9%) with catheters had vascular factors or medical contraindications that preclude AV access placement.

MacRae et al., 2005 and Yuan et al., 2007, report that 40% of patients who undergo venography have central venous stenosis from long-term catheter use, which may preclude later AVF creation or hamper maturation. Furthermore, patients who have had a CVC placed before AVF creation have reduced fistula survival, as compared to patients who did not have a CVC (Pisoni et al., 2002; Hakim & Himmelfarb, 1998; Ravani et al., 2005). Although our project did not include assessment for central venous stenosis, all three patients who experienced primary AV access failure as a result of the conversion project had a history of central venous stenosis, had long-term catheter use, and a history of previous failed fistulas.

In an effort to improve AV access survival, all patients who agreed to conversion were scheduled for preoperative bilateral arterial and venous arm mapping. A recent randomized trial by Ferring et al. (2010) found that preoperative venous mapping resulted in improved AVF outcomes and patency rates and is also recommended in both National and European guidelines (Ferring et al., 2010; NKF-KDOQI, 2006; Tordoir, et al., 2007).

Incident rates

Although it is expected that patients who are followed in the CKD clinic would be more likely to convert to AV access, this was not the case at our centre. In fact, despite a structured team approach to patient care, 70% of incident patients in our centre initiated HD with a CVC during the project period, which is similar to other centres in Canada (Mendelssohn et al., 2006a).

In order to successfully reduce the use of CVCs for vascular access, we need to develop a better understanding of the patient's perspective and possible psychological factors affecting patients' decisions.

Patient's perspective and patient satisfaction

Despite repeated efforts to inform patients of the numerous disadvantages of long-term catheter use and the benefits of AV accesses, patients continue to "fall in love" with their catheters and, worse, often choose to remain with a catheter even when the risks are explained to them. As health care providers, we need to explore patients' perspectives and factors that affect patient satisfaction if we are to succeed in reducing catheter rates among Canadian catheter-dependent patients. Based on the main findings in our study, patients were most concerned about insertion of needles, pain and the appearance of their AV access.

Similarly, other studies report that prevalent catheterdependent patients are influenced by other patients' experiences with cannulation; mainly pain, difficulty placing needles, large bumps on arms, and bleeding after dialysis (Asif et al., 2005; Bay, Van Cleef, & Owens, 1998; Lee, Barker, & Allon, 2005; Quinn et al., 2008; Yuan et al., 2007).

Quinn et al. (2008) developed a vascular access questionnaire assessing patient-reported views and patient satisfaction with their vascular access in an effort to better understand patient perspectives and the challenges that health care providers face when trying to increase fistula usage. They found that patients who had fistulas were most concerned with appearance of their vascular access and cannulation-related complications such as pain, bleeding, bruising and swelling. Interestingly, only 3% of catheter-dependent patients reported that they were concerned about infection, yet this is a major concern for physicians. The authors suggest that this may be the result of inadequate education about the risks of CVC or that patients are more concerned about issues they are bothered by frequently. Furthermore, Quinn et al. (2008) suggest that implementing strategies aimed at reducing cannulation-related complications may lead to an increase in fistula rates and improve patient satisfaction with their vascular access.

Strategies aimed at improving the likelihood of successful cannulation may include assigning nurses deemed as expert cannulators to all new and difficult vascular accesses, thereby reducing trauma caused by unsuccessful cannulations; improving nurses' cannulation skills through mentoring and coaching by utilizing the clinical renal educator or expert cannulators, matching the skill of nurses to the difficulty of the AV access; and cohorting patients based on access type and cannulation difficulty. These strategies may help to improve fistula development and maturation and, ultimately, lead to patient compliance and patient satisfaction with vascular access (Wilson, Harwood, Oudshoorn, & Thompson, 2010).

Patient choice

Yet, for many patients receiving dialysis with a CVC, the decision to undergo surgery for the creation of an AV access, which will ultimately involve placing needles into their arm every dialysis, can be a difficult one. According to Lee et al. (2005), many patients on HD who have experienced access failure in the past are reluctant to undergo further access surgery, knowing the possibility that the access may fail again.

Rehman, Schmidt and Moss (2009) suggest that patient choice may be confounded by care providers' wish to respect patient choice, and thereby failing to adequately and accurately inform patients about the risks and benefits of CVC use for vascular access. Furthermore, they suggest that nephrologists have an ethical obligation to inform patients about the risks of CVC, to promote AV fistulas as the vascular access of choice, and to present CVC only as a temporary measure, or as a last resort. Rehman et al. (2009) suggest that patients cannot make truly autonomous decisions if they are not adequately informed, and Blackhall (1987) states that autonomy does not allow patients to demand treatments where the risk outweighs the benefit.

Lok (2007) suggests that "high-risk patients who have recurrent AVF failure will ultimately succumb to surgical fatigue and refuse future efforts for a permanent AVF" (p. 1050). Asif et al. (2005) agrees that the eventual exhaustion of traditional vascular access sites in long-term HD patients who have suffered multiple failed AV accesses contributes to catheter use. Therefore, timely access to a vascular surgeon, creation of AV access among incident patients, conversion of suitable prevalent patients from CVC to AV access, and a change in catheter culture are critical to reduce long-term catheter use for HD treatment.

A strength of our study is that it is a prospective, real-life, quality improvement experience in a busy HD unit, incorporating a multifaceted, multidisciplinary approach. Our three-step approach of assessing prevalent catheter-dependent patients for suitability has resulted in conversion of 41.5% of patients from CVC to AV access, and continues to be implemented as a strategy for assessing and converting suitable patients. A most striking finding of our study is that despite a prevalent AVF rate of 58% and AVG rate of 4% at the start of the project, using a rigorous multifaceted and multidisciplinary approach, we still found more prevalent catheter-dependent patients to convert to AV access.

A limitation of our project is that it represents the experience of a single centre quality improvement initiative and was not designed as a randomized controlled clinical trial. While the three-step process was used on all patients and all patients in our study received the same patient information sheet, it is hard to determine whether the fable alone or the overall threestep process was effective in the conversion of patients to AV access. It should be noted that our results are based on current practices, preferences, and surgical expertise of our vascular surgeon and, therefore, may not be generalizable to other HD centres.

Implications for practice

As a result of our conversion project, all patients who initiate dialysis acutely (deemed to have chronic renal failure), and who have been followed in the CKD clinic are assessed for AV access. Early discussions by the clinical nurse specialist with patients and families are now routine practice, with an emphasis that catheters are considered a temporary access for HD until AV access is established. All catheter-dependent patients are given detailed written information on the advantages of AV access and the disadvantages of CVCs, scheduled for preoperative bilateral arterial and venous arm mapping, and referred to the vascular surgeon for AV access creation. Discussions between patients who have successfully converted to an AV access and patients who have a functioning AV access are also encouraged.

Strategies aimed at improving patient, family and staff education about the risks of long-term catheter use and implementing measures to reduce cannulation-related complications may improve patients' satisfaction with their vascular access, conversion of catheter-dependent patients to AV access, increase fistula rates, help improve fistula development and maturation and, ultimately, lead to improved patient compliance and patient satisfaction.

Our three-step conversion project including fable and results is on display in the HD unit and the CKD clinic, emphasizing to patients, families and staff that CVCs are considered temporary accesses for HD, and that AV accesses are the preferred vascular access. Although we were unable to demonstrate in our study design that the fable alone was effective in converting patients to AV access, its effect on patients' decision to convert to AV access should not be dismissed.

Implications for future research

It is difficult to reconcile with the fact that 44/95 (46%) patients were deemed unsuitable for conversion in our study, when the experiences in parts of Europe and Japan suggest that AVF rates of more than 70% to 90% respectively are achievable (Hakim, & Himmelfarb, 1998; Lazarides et al., 1996). It is possible that our criteria for determining medical suitability were too stringent, and that another centre could have created a larger pool of suitable patients. Nonetheless, based on these encouraging results, we recommend larger, better designed studies be done in the future.

Recommendations for further research into this area include examining psychological factors affecting a patient's resistance to conversion and whether nurses could play a more active role; implementing strategies aimed at reducing cannulation-related complications, changing the Canadian CVC culture to promote AV access for all suitable patients, randomized control studies to assess the effectiveness of the fable and other written materials geared to patients who start dialysis acutely and prevalent catheter-dependent patients, and examining teaching methods such as videos and support groups.

Conclusion

Conversion of catheter-dependent patients to alternate forms of vascular access is challenging. Our three-step multidisciplinary approach proved to be a successful strategy in converting medically suitable prevalent catheter-dependent patients to an AV access. As a result of our conversion strategy, 41.5% of patients who previously relied on a CVC as a longterm vascular access have successfully converted to AV access.

We believe that our results are reproducible and such an approach can be implemented in other busy HD units.

Our three-step multidisciplinary approach has led to a more structured method of assessing a patient's suitability for AV access creation, and continues to be implemented as a conversion strategy in our centre for all catheter-dependent patients and after every AV access failure.

As we encountered a large number of patients who refused conversion (27 patients), we suggest that more research into surmounting the psychosocial aspects of resistance to conversion is required. It should be noted that the waiver did not prove to be effective in persuading our patients to agree to conversion to an AVF or AVG, but may be helpful for medicolegal reasons. Initially we estimated that 50% of patients who were asked to sign the waiver would have agreed to conversion when, in fact, no patient agreed to conversion. As a result, the waiver is no longer used at our centre.

Long-term CVC use in Canada and the unwillingness of medically suitable patients to convert to more optimal forms of vascular access are linked problems with potentially grave consequences. We call for better designed studies with empirical methodologies to be a priority in this area.

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By Patty Quinan, RN, MN, CNeph(C), Aaron Beder, MD, FRCSC, Murray J. Berall, MD, FRCPC, Meaghan Cuerden, MSc, Gihad Nesrallah, MD, FRCPC, and David C. Mendelssohn, MD, FRCPC

Patty Quinan, RN, MN, CNeph(C), Clinical Nurse Specialist--Dialysis Access, Department of Nephrology, Humber River Regional Hospital, Toronto, Ontario.

Aaron Beder, MD, FRCS, Department of Vascular Surgery, Humber River Regional Hospital, Toronto, Ontario.

Murray J. Berall, MD, FRCPC, Department of Nephrology, Humber River Regional Hospital, Toronto, Ontario.

Meaghan Cuerden, MSc, Division of Nephrology, the University of Western Ontario, London, Ontario.

Gihad Nesrallah, MD, FRCPC, Department of Nephrology, Humber River Regional Hospital, Toronto, Ontario, Division of Nephrology, the University of Western Ontario, London, Ontario, and Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario.

David C. Mendelssohn, MD, FRCPC, Department of Nephrology, Humber River Regional Hospital, Toronto, Ontario, and Division of Nephrology, University of Toronto, Toronto, Ontario.

Address correspondence to: Patty Quinan, RN, MN, CNeph(C), Clinical Nurse Specialist--Dialysis Access, Humber River Regional Hospital, Toronto, ON. Email: PQuinan@HRRH.ON.CA

Submitted for publication: September 21, 2010. Accepted for publication in revised form: February 14, 2011.

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