| Temporary venous access (usually less than 2–3 weeks) | Permanent access for ESRD |
|---|---|
| Single- or double-lumen (Mahurkar type) catheter into the subclavian vein | Arteriovenous fistula using autogenous saphenous vein or graft using PTFE |
| Silastin-Teflon shunt for CAVH or CAVHD | Dacron-cuffed double-lumen silicon catheter (Permcath) surgically inserted into the subclavian or internal jugular vein through a subcutaneous tunnel; rarely used. |
| Twin wide-bore femoral catheter for CAVH or CAVHD | Scribner arteriovenous shunt, now used infrequently |
| Temporary venous access in ESRD: single- or double-lumen venous catheter inserted over guidewire into the subclavian, femoral,a or internal jugular vein |
Abbreviations: ESRD = end-stage renal disease; PTFE = polytetrafluoroethylene; CAVH = continuous arteriovenous hemofiltration; CAVHD = continuous arteriovenous hemodialysis.
a Femoral vein placement is associated with high rate of infection, so it is usually removed by 72 hours.
An arteriovenous (A-V) fistula is an anastomosis of the radial artery to the cephalic vein. Other vessels in the upper arm can also be used. An A-V graft uses a tube made of polytetrafluoroethylene (PTFE, Teflon) to make the A-V connection.
Infectious complications of vascular access devices
In 2006, over 80% of patients began HD with catheter access while in 2007, 23% of patients on HD were using a catheter. Each dialysis session requires four tubing connections, thus a high risk for introduction of microbes through the hub and lumen of catheters. The reported catheter infection rate ranges from 3.8 to 6.6 episodes per 1000 days for nontunneled catheters vs. 1.6 to 5.5 episodes per 1000 days for tunneled catheters, both of which are markedly higher than for A-V fistulas and grafts. The relative risk for infection-related hospitalization and death is increased 2- to 3-fold for catheter-dependent HD patients compared to those with A-V fistulas. Local infections occur at the exit site or in the tunnel of percutaneously inserted silicone catheters. The clinical presentations of exit-site infection include pain, erythema, tenderness, induration, and purulent discharge within 2 cm of the site. Tunnel infections are associated with pain, erythema, tenderness, or induration involving the subcutaneous tract of the catheter. Infection of autologous A-V fistulas and prosthetic PTFE A-V grafts manifests as cellulitis, perifistular abscess, false aneurysm, draining sinus, and in PTFE fistulas, bleeding when the grafts’ suture lines are involved. Fever, leukocytosis, or left shift in the differential leukocyte count may be present.
Both exit-site and tunnel infections may be complicated by concomitant bacteremia, sepsis, and suppurative thrombophlebitis. Bacteremia may lead to metastatic foci of infection, including septic arthritis, septic pulmonary emboli, endocarditis, osteomyelitis, brain abscess, and splenic abscess. Bacteremia and sepsis often present without signs or symptoms of infection at the vascular access site. Catheter-related colonization without clinical manifestations of infection has been reported in up to 55% of HD catheters. Most catheter-related bloodstream infections (CR-BSI) arise from the lumen following bacterial colonization and biofilm formation. Eradication of bacteria in endoluminal biofilm requires very high concentrations of antibiotics (up to 1000 times the concentrations needed to kill bacteria in solution). Systemic antibiotic therapy alone without catheter removal yields cure in only one-third of these CR-BSI.
Microbiology
A specific microbiologic diagnosis of access-related infection can frequently be made by Gram stain and culture of purulent material from the cannula exit site or with A-V fistulas from needle exit sites or abscess fluid. In addition, blood cultures drawn from the access device along with other peripheral sites should be obtained to aid in identification of access site as origin of infection. Access site origin of bacteremia is suggested if either quantitative blood cultures have colony counts from catheter blood that are 3-fold greater than from peripheral blood cultures or catheter blood cultures have an earlier time to positivity (at least 2 hours) compared to the time to positivity of blood cultures from another site. The organisms responsible for access device infection are shown in Table 96.2.
| Hemodialysis | Peritoneal dialysis |
|---|---|
| Staphylococcus aureus (50%–80%) Other gram-positive bacteria (S. epidermidis, streptococci, including enterococci, diphtheroides), gram-negative organisms (Escherichia coli, Pseudomonas aeruginosa, Acinetobacter spp., and other enteric gram-negative bacteria) (15%–30%) Occasionally fungi | Staphylococcus epidermidis and S. aureus (50%) Other gram-positive bacteria (streptococci, including enterococci, diphtheroides) Gram-negative organisms (E. coli, P. aeruginosa, Acinetobacter spp., and other enteric gram-negative bacteria) Occasionally fungi |
Percentages in parentheses are approximate proportional incidence from numerous references.
Therapy
Therapy is based on the results of cultures from infected sites and blood. Initial management plans are shown in Table 96.3. Additionally, relative indications for removal of either catheter or A-V fistula or graft include: suppurative thrombophlebitis, septicemia, bacteremia with metastatic foci of infection, infections caused by Staphylococcus aureus, Pseudomonas aeruginosa, mycobacteria, and fungi, lack of response to medical therapy within 48 to 72 hours, and recurrent infection in a catheter with the same pathogen. Tunnel infection associated with catheter access requires removal of the catheter. Any associated fluid collections associated with an A-V fistula or graft should be drained. In the absence of exit-site and tunnel infection, sepsis, or metastatic foci of infection, exchange of the catheter over a guidewire may be attempted. If there is no resolution of fever, bacteremia, or fungemia in 48 to 72 hours the catheter should be removed. CR-BSI caused by coagulase-negative staphylococci (not S. aureus or fungi) seem very amenable to guidewire exchange. Intravenous (IV) vancomycin is often used in initial therapy for access device infections as methicillin-resistant Staphylococcus aureus (MRSA) staphylococci are the most common pathogen. The type of dialyzer, dialysis flow rate, patient size, and level of residual renal function can make vancomycin serum levels difficult to predict. Therapy should be initiated with a loading dose of 15 to 25 mg/kg of vancomycin given preferably after dialysis. The second dose, 5 to 10 mg/kg, is given after the next dialysis session. Before the third dialysis session a predialysis serum vancomycin level should be done and used to determine the vancomycin dose to be given after the third dialysis session. A standard postdialysis dose can be started once target serum concentrations have been achieved. Other antimicrobials with good activity against staphylococci are alternatives to vancomycin. Linezolid or daptomycin can be used in patients with allergy to vancomycin or for organisms with reduced sensitivity to vancomycin. Dose of daptomycin is 4 mg/kg or if bacteremia is present, 6 to 8 mg/kg, every 48 hours (preferably after dialysis), and for linezolid, 600 mg IV every 12 hours. Methicillin-sensitive staphylococci (MSSA) should be treated with nafcillin, 1 to 2 g IV every 4 to 6 hours.
| Type of infection | Therapy |
|---|---|
| Exit-site infection in a temporary access device with or without bacteremiab | Catheter removal and vancomycin,a 1 g IV; subsequent doses based on serum levels; aminoglycosides or broad-spectrum β-lactam antibiotics if gram-negative organisms suspected |
| Tunnel infectionb | Catheter removal and antibiotics as above |
| Catheter-related sepsis | Catheter removal; empiric broad-spectrum antimicrobial therapy with vancomycin and gentamicin, 1.5 mg/kg IV in a single dose; subsequent antimicrobial therapy based on pathogen and sensitivity pattern |
| Suppurative thrombophlebitis | Catheter removal, antimicrobial therapy based on pathogen and sensitivity pattern; surgical consultation for possible exploratory venotomy |
| Arteriovenous fistula infection | Vancomycin and gentamicin as above; incision and drainage of abscess; ligation or removal of prosthetic arteriovenous fistulas for occlusion or tunnel infection or if response to treatment is not prompt; surgical repair of a malfunctioning infected shunt may be possible |
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
