**1. Introduction**

86 Technical Problems in Patients on Hemodialysis

Wuerth D, Finkelstein SH & Finkelstein FO. (2003). Chronic peritoneal dialysis patients

Yeh SJ & Chou HC. (2007). Coping strategies and stressors in patients with hemodialysis.

*dialysis* 16(6): 424:427

*Psychosomatic Medicine* 69(2): 182-190

diagnosed with clinical depression: results of pharmacological therapy. *Seminars in* 

Renal replacement therapy (RRT), including various delivery types of haemodialysis, has revolutionised the care of patients with end stage renal disease (ESRD). The most common RRT modality is haemodialysis (ANZ Data 2010, Boddana et al., 2009). Access for dialysis is via arteriovenous fistulae (AVF), arteriovenous grafts (AVG) or via central venous dialysis catheters. The goal of access is to provide a means of accessing the vasculature to undertake RRT in order to deliver the optimal dialysis dose with the minimal associated morbidity and mortality. The National Kidney Foundation (NKF) Kidney Disease Outcome Quality Initiative (KDOQI, 2006) guidelines recommend an AVF prevalence rate of greater than 65%. Arteriovenous fistulae remain the preferred method of access due to improved survival rate and lower associated morbidity and associated medical costs (NKF-KDOQI, 2006). Despite all these measures, dialysis catheters remain commonly used for a variety of reasons. They are now well acknowledged as the harbinger of potential future significant morbidity and mortality.

As a result of the significant morbidity burden caused by dialysis catheters, there has been great interest in discovering new and inventive methods of reducing catheter-related infection. Out of this is borne the investigation of preventative measures outlined here. This is particularly important given the immunosuppressed nature of renal patients. The evidence for, and utility of measures, such as topical antimicrobial ointment application, antimicrobial catheter lock solutions, antibiotic impregnated catheters, differing AVF cannulation methods and catheter design, shall be explored below.

As we strive for improved outcomes in our patients many more patients are undertaking extended hours home haemodialysis. In those patients with the lowest risk accesses, questions have been raised as to the method of access cannulation and the spectre of increasing associated infectious events. The rope ladder technique involves regular rotation of cannulation sites whereas buttonhole technique uses the same cannulation sites and relies on formation of a track which is then repetitively accessed with blunt needles. This has been a very attractive method for home dialysis patients for a range of reasons. However, despite recent popularity with this technique, a number of studies including from our centre, have now shown that this technique is associated with increased septic events (Birchenough et al., 2008; Nesrallah et al., 2010; Van Eps et al., 2010; Van Loon et al., 2010).

Hemodialysis Access Infections, Epidemiology, Pathogenesis and Prevention 89

and increased mortality from both infective and non-infective causes (Dhingra et al., 2001; Pastan et al., 2002; Polkinghorne et al., 2004). One study analysed a random sample of patients from the U.S. Renal Data System Dialysis Morbidity and Mortality Study (USRDS) Wave 1. Both diabetics and non-diabetics with catheters demonstrated similar trends in survival. The best overall survival was observed with AVF over AVG. The poorest survival was seen in patients with catheters (Dhingra et al., 2001). This increased mortality observed with AVGs and catheters has been replicated in a number of studies (Pastan et al., 2002; Polkinghorne et al., 2004; Xue et al., 2003). One of the largest investigations of access-related mortality included over 60,000 patients from the United States (Xue et al., 2003). The use of catheters at iniation of dialysis was associated with the greatest mortality risk (catheter hazard ratio [HR] 1.70, 95% CI 1.59-1.81; AVGs HR 1.16, 95% CI 1.08-1.24; AVF reference). .

A *prospective* study of almost 1000 patients in France looked at the risk factors for development of bacteraemia in chronic haemodialysis patients (Hoen et al., 1998). This again confirmed that the greatest risk factor for bacteraemia was use of a dialysis catheter, with an incidence of 0.93 episodes of bacteraemia per 100 patient months. Multivariate analysis confirmed vascular access as a major risk factor for bacteraemia. Catheter use for haemodialysis carried a relative risk of bacteraemia of greater than 7 times that of an AVF (relative risk [RR] 7.6, 95% CI 3.7-15.6). Arteriovenous grafts carried only a marginally

Access-related bacteraemia has also been shown to be an important factor in the subsequent development of cardiovascular-related morbidity and mortality. Where cause-specific mortality was assessed, increases in both infectious deaths (Dhingra et al., 2001; Ishani et al., 2005; Pastan et al., 2002; Polkinghorne et al., 2004) and cardiac deaths were also observed (Dhingra et al., 2001; Ishani et al., 2005). Interestingly, in one study, non-diabetics using catheters at the inception of dialysis had a worse survival rate than those patients using permanent vascular access, with the difference being detectable after only 2 months of observation. The overall relative risk of infection-related death was approximately 2-fold higher in patients with central venous catheters over those with AVFs and was more marked in diabetics than non-diabetics. The risk of death from cardiac causes was approximately 1.5-fold higher in those with dialysis catheters (Dhingra et al., 2001). A prospective cohort study of incident dialysis patients in the U.S scrutinised the association between access modality and bacteraemia, and also the association between bacteraemia and cardiovascular events (Ishani et al., 2005). Cox regression analysis (n=2358) demonstrated that initial dialysis access was the main antecedent of septicaemia or bacteraemia. Long term dialysis catheters, temporary dialysis catheters and AVGs displayed HRs of 1.95, 1.76 and 1.05, respectively. The presence of bacteraemia or septicaemia was associated with heightened risks of subsequent cardiovascular morbidity and mortality. In those without defined coronary artery disease, a bacteraemic episode conferred a greater risk of death or acute cardiovascular event than those with pre-

A study undertaken in Australia examined incident haemodialysis patients between 1999 and 2002, and made further attempts to statistically adjust for the non-random nature of access selection. This study found that those patients starting dialysis with a dialysis catheter or AVG had a greater risk of dying in the first 6 months compared to those with AVF; catheters being the most life-limiting of all three. This trend continued with time. Dialysing via an AVF showed a mortality rate of 86 per 1000 person-years; AVGs had a

In this study, greater than 50% of patients commenced dialysis with a catheter.

higher relative risk compared to AVFs.

existing cardiovascular disease.
