The Air-Bubble Method of Locking Central-Vein Catheters with Acidified, Concentrated Sodium Chloride as a Bactericidal Agent: In Vitro Studies

Background:  Soft, cuffed indwelling catheters are used for hemodialysis access and intravenous infusions. The majority of these catheters are removed as a result of infection caused by contamination of the catheter hub during the connection/disconnection procedures. To prevent clot formation in the lumen, these catheters are routinely "locked" with heparin or some other anticoagulant. None of the anticoagulants commonly used as locking solutions demonstrates any significant bactericidal properties. The primary goal of this study was the development of a catheter locking method that retains anticoagulant properties at the catheter tip and bactericidal properties at the catheter hub. The second goal was to find a solution that possesses excellent bactericidal properties but is not detrimental in the event of injection into the patient's blood stream. The bactericidal properties of acidified, concentrated saline (ACS) were compared to concentrated trisodium citrate and to commonly used bactericidal agents such as povidone iodine, sodium hypochlorite, and chlorhexidine.
Methods:  In preliminary studies, the rate of diffusion of solutes was measured in glass tubes. In another set of experiments, the mixing of two solutions (anticoagulant and bactericide) separated by an air bubble ("air-bubble method") was observed in stationary and moving systems. The final series of studies compared the bactericidal properties of ACS to other bactericidal solutions mentioned above.
Results:  The solutions diffused swiftly in the glass tubes, and by the third day, both solutions were mixed. The air-bubble method prevented mixing in both stationary and moving systems. The bactericidal properties of ACS were superior to all other tested solutions.
Conclusions:  The proposed method of catheter locking with anticoagulant at the catheter tip and ACS at the catheter hub separated by an air bubble is a promising technique and clinical studies are warranted.     

Concentrated Sodium Citrate (23%) for Catheter Lock

For chronic central venous dialysis catheters, the standard method for maintaining catheter patency between treatments is to instill (lock) catheters with 5000 – 10 000 units of heparin in each lumen. Sodium citrate (citrate) is an anticoagulant with intrinsic antibacterial activity (at 20% concentration or higher). Citrate has only transient anticoagulant effects if accidentally infused to the patient. Prior studies of citrate as a catheter lock solution have utilized citrate concentrations of 1% in combination with 27 mg/mL gentamicin. We changed clinical protocols for catheter locks using various solutions, including concentrated citrate, in a dialysis unit with 50% of patients having chronic central venous catheters [40 catheters total, mostly Ash Split Cath (Medcomp, Harleysville, PA, U.S.A.) but some Tesio (Medcomp) and Hickman (BARD, Salt Lake City, UT, U.S.A.) catheters]. At 3‐ to 4‐month intervals, the standard catheter lock solution for the unit was varied on the following schedule: heparin; 10% citrate with 3 mg/mL gentamicin; 20% citrate with 3 mg/mL gentamicin; heparin; and 23% citrate. Catheters were not routinely removed during treatment of bacteremia. Incidence of bacteremia in patients with catheters using heparin as catheter lock was 4.32 episodes per 3000 patient‐days (equivalent to percent of patients with catheters having bacteremia per month). The incidence of bacteremia decreased to 1.68 using 20% citrate/gentamicin as catheter lock (p < 0.05) and to 0% with 47% citrate (p < 0.05). Incidence of bacteremia increased on return to heparin and decreased again with use of 23% citrate to 1.79 (p < 0.05). Use of urokinase for occluded catheters also significantly decreased with citrate during the time that it was available (p = 0.02). Life table analysis indicated an 83% survival of Ash Split Cath catheters at 1 year, in this unit. Concentrated citrate is an effective catheter lock solution that may provide prolonged central venous catheter use with a diminution in catheter‐related infections and occlusion.     

Low dose heparin lock (1000 U/mL) maintains tunnelled hemodialysis catheter patency when compared with high dose heparin (5000 U/mL): A randomised controlled trial

Introduction Heparin is commonly used after hemodialysis treatments as a locking solution to prevent catheter thrombosis. The comparative efficacy and safety of different heparin concentrations to maintain catheter patency has been previously reported in retrospective studies. We conducted a prospective, randomised, controlled study of 1000 U/mL heparin (low dose) versus 5000 U/mL heparin (high dose) locking solution to maintain patency of tunnelled catheters. Methods One hundred patients receiving chronic, unit‐based hemodialysis with newly placed tunnelled hemodialysis catheters (less than 1 week) were randomly assigned to either a low dose (n = 48) or high dose heparin (n=52). The primary intention‐to‐treat analysis examined time to malfunction in both groups over a 90 day period. A secondary analysis compared baseline patient characteristics in relation to catheter malfunction. Findings Overall rate of catheter patency loss was 32% of catheters by 90 days. There was no significant difference in time to malfunction of catheters locked with low dose or high dose heparin (P = 0.5770). Time to catheter malfunction was not associated with diabetic, hypertensive or smoking status. There was no difference in mean delivered blood flow rate, venous and arterial pressure, and dialysis adequacy between low dose and high dose groups. No patient suffered a hemorrhagic complication requiring hospitalisation during the study period. Discussion Low dose heparin is adequate to maintain tunnelled hemodialysis catheter patency when compared with high dose heparin. The study also suggests that there is no relationship between catheter malfunction and diabetic, hypertensive or smoking status.     

Antibiotic lock: In vitro stability of gentamicin and sodium citrate stored in dialysis catheters at 37 °C

Catheter‐related bacteremia (CRB) is a major cause of morbidity and mortality especially among patients receiving hemodialysis. Antibiotic lock therapy represents a promising technique in the treatment of CRB. Several studies have evaluated antibiotics in combination with heparin as an interdialytic locking solution for prophylaxis of CRB. The objective of this study was to evaluate the stability of gentamicin and sodium citrate in hemodialysis catheters as an interdialytic lock. Solutions containing gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) were prepared individually and in combination. The solutions were instilled into dialysis catheters and stored at 37 °C for 96 h. Samples were withdrawn randomly from catheter lumens at 24‐hour intervals for 4 days and stored at ?20 °C until analysis. The samples were analyzed with validated, stability‐indicating HPLC assays. The luminal concentration of gentamicin 2.5 mg/mL, sodium citrate 40 mg/mL (4%), and the combination was determined on study days 0, 1, 2, 3, and 4. When gentamicin was combined with sodium citrate and stored at 37 °C in dialysis catheters, the solution showed no decrease in either the gentamicin or the sodium citrate concentrations over the 96‐hour study period. The percent of the original concentration at 96 h was 102.4±1.03 for gentamicin and 102.9±1.25 for citrate (P=0.5556). The combination of gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) can be retained in hemodialysis catheters for at least 96 h at 37 °C with no evidence of degradation.     

Catheter lock heparin concentration: effects on tissue plasminogen activator use in tunneled cuffed catheters

The optimal cost-effective heparin concentration for locking tunneled cuffed hemodialysis catheters (TCC) is unclear. We performed a retrospective review of tissue plasminogen activator (tpa) use in TCC in 2 hemodialysis units that used different heparin concentrations for TCC lock to evaluate the effectiveness of lower dose heparin as a lock for TCC. Catheter blood flow rate per treatment, units of heparin given during treatments, patient hemoglobin values and use of warfarin, and tpa use were compared for all patients using TCC for at least 3 months in 2 in-center hemodialysis units between 11/04 and 5/05. Both units used the same type of catheters and biocompatible, non-re-use dialyzers. Unit A used heparin 1000 U/mL for catheter locks, and Unit B used heparin 10,000 U/mL for catheter locks. Twelve of 19 Unit A patients, tpa and 14 of 45 Unit B patients received intracatheter during the study period (p=0.0009). There were no differences in the number of patients on warfarin, treatment blood flow rate, or mean hemoglobin levels between the 2 groups. The mean heparin units given during hemodialysis treatments was higher in Unit A patients (3.92+/-2.2 vs. 3.83+/-2.5 1000 U, p=0.05). Assuming a 4.1 mL total catheter lumen volume, the cost of heparin 1000 U/mL lock was 0.20 dollars per treatment and heparin 10,000 U/mL cost 2.67 dollars/treatment; tpa cost 89.02 dollars/use. Using the 10,000 U/mL heparin as a catheter lock was associated with less frequent use of tpa. However, the significantly lower cost of the 1000 U/mL heparin could result in significant savings despite higher tpa use. This retrospective, uncontrolled study of a small number of patients suggests that comparing low and high heparin concentrations as a TCC lock would be worthwhile. Prospective studies would be helpful to define the most appropriate and cost-effective lock for TCC.     

Ethanol combined with heparin as a locking solution for the prevention of catheter related blood stream infections in hemodialysis patients: A prospective randomized study

Introduction: Ethanol lock solution has been mainly administered in paediatric and home parenteral nutrition patients in order to prevent catheter related blood stream infections (CRBSI). Its utility in hemodialysis (HD) patients with non‐tunneled‐uncuffed catheter (NTC) has been poorly explored. Methods: We conducted a prospective randomized study in chronic HD patients requiring a newly inserted NTC‐while awaiting for the maturation of an already established arteriovenous fistula (AVF) or arteriovenous graft (AVG) or tunneled‐cuffed catheter insertion. Patients were randomized in two groups: Group A, where the lock solution was ethanol 70% + unfractionated heparin 2000 U/mL and group B, that received only unfractionated heparin 2000 U/mL. Primary end point was CRBSIs whereas exit site infections, thrombotic and bleeding episodes were the secondary end points. Findings: One hundred three HD patients were enrolled in the study (group A, n = 52; group B, n = 51). The median number of catheter days was 32 for group A (range: 23–39) and 34 (range: 27–40) for group B with no statistically significant difference between the two groups. Group A (ethanol + heparin) demonstrated 4/52 episodes (7.69%) of CRBSI whereas Group B (heparin) 11/51 episodes (21.57%) (P = 0.04). CRBSI rates per 1000 catheter days were 2.53/1000 catheter days for group A and 6.7/1000 catheter days for group B (P = 0.04). Mean cumulative infection‐free catheter survival in the ethanol group did not differ significantly compared to the heparin group (log‐rank test = 2.99, P = 0.08). Thrombotic episodes did not differ between the two groups. Discussion: Locking of NTCs in HD patients with ethanol 70% + unfractionated heparin reduces CRBSI rates without increasing the thrombotic episodes.     

Clinical consequences of heparin-free hemodialysis

Heparin-free hemodialysis (HF-HD) has been increasingly used in patients at risk for bleeding, especially in the intensive care unit (ICU). Lack of heparin can reduce solute clearances in continuous hemofiltration; the effect on HD is undefined. Failure to recognize an effect of the anticoagulation strategy upon delivered clearance could contribute to the known problem of underdialysis in the ICU. In addition, the consequences of "locking" dialysis catheters with concentrated heparin solutions are also unclear. This study was designed to define the clinically relevant consequences of HF-HD and catheter locking. In part I, we performed 200 HD treatments on inpatients, of which 100 were performed with heparin, and 100 were performed as HF-HD. We calculated prescribed and delivered Kt/V and dialysis efficiency. In part II, a separate group of 14 patients undergoing HF-HD via central venous catheters had measurement of activated partial thromboplastin time (aPTT) during the last hour of dialysis, as well as 15, 60, and 240 min after catheters were locked with 1:5000 heparin. The prescribed Kt/V was 1.74+/-0.31 for standard HD with heparin vs. 1.66+/-0.36 for HF-HD (p=ns). The delivered Kt/V was 1.42+/-0.32 vs. 1.36+/-0.38 (p=ns). Efficiency was 0.82 vs. 0.84 (p=ns). Baseline aPTT was 28+/-5 s, and increased to 126+/-54 s, 15 min after locking (p<0.0001) and to 71+/-50 s, 60 min after locking (p=0.005). By 240 min, the mean aPTT had fallen to 33+/-9 s (p=0.03), although individual values were still as high as 50 s. The HF technique does not compromise delivery of dialysis to inpatients. Increased treatment time is not necessary. Locking catheters with heparin after HF-HD resulted in prolonged unintentional anticoagulation.     

Maintenance of blood flow rate on dialysis with self‐centering CentrosFLO catheter: A multicenter prospective study

Introduction Chronic central venous catheters (CVC) for dialysis lose patency and deliver lower blood flow over time, often due to fibrous sheathing that covers the lumen tips. The CentrosFLO central venous catheter has a shape that directs the arterial and venous tips away from the walls of the vena cava and right atrium, making sheathing of the tips less likely. Methods A prospective, multicenter, single arm, non‐controlled, observational study was conducted at eight sites in the United States. All consenting dialysis patients receiving CentrosFLO catheters through the right or left internal jugular veins were accepted in the study, as long as the catheter was expected to be used for 45 days and was not an over‐the‐wire replacement for a previous CVC. Data were automatically collected on initial and average dialysis blood flow rate and initial arterial and venous pressures, for up to 26 weeks of dialysis therapy. Findings 75 patients were enrolled. Kaplan‐Meier analysis indicated that 87% of patients maintained blood flow rate over 300 mL/min throughout 26 weeks of follow‐up. There was no decline in average dialysis blood flow rate and no significant change in hydraulic resistance of the arterial or venous lumens of the catheters during the study. Discussion The CentrosFLO catheter demonstrates long term patency with good flow rates on dialysis, which, by comparison with previous studies, shows a clinically significant improvement in blood flow rate vs. other catheters. Stable hydraulic resistance of the catheter lumens showed no evidence of tip encroachment by fibrous sheaths.     

Do Catheter Side Holes Provide Better Blood Flows?

Four catheters (Ash Split Cath, Tesio, Duo‐Split, and Duo‐‐Flow; Medcomp, Harleysville, PA, U.S.A.) were tested in a temperature‐controlled in vitro setup filled with 50% aqueous glycerin solution to determine hydraulic resistance at different flow rates. All these catheters have side holes; hydraulic resistance was determined with these holes open and closed. Due to extra pressure losses near the catheter tip, the pressure–flow relationship deviates from Poiseuillian theory and is generally quadratic in nature. An equivalent diameter was derived from the data. This equivalent diameter can be used to evaluate performance using a single number. Permanent catheters can easily deliver 300 mL/minute under optimal circumstances, but acute catheters are, in practice, limited to 200 mL/minute, and even somewhat less in the coaxial Duo‐Flow type. Permanent catheters have larger equivalent internal diameters (1.8 vs 1.45 mm). Covering the side holes does not influence hydraulic resistance to a great degree, except in the arterial limb of acute catheters. These results indicate that, especially in acute catheters, obstruction of the side holes or fibrin sleeve/thrombus formation over the inlet holes may severely impact the available blood flow rate during dialysis. On the other hand, side holes in permanent catheters or venous limbs seem to be superfluous for performance reasons.     

Efficacy of preventing hemodialysis catheter infections with citrate lock

Prevalent use of tunneled dialysis catheters can reach 30%. Infection remains the most serious catheter‐related problem. Catheter locks are increasingly used for prevention, but are not yet recommended either by the Food and Drug Association or European Medicines Agency, on the basis of increasing bacterial resistance or lock toxicity. The aim was to test safety and effectiveness of citrate. A prospective, interventional study was conducted to assess the safety and efficacy of a 30% citrate lock in preventing catheter‐related bacteremia (CRB). A total of 157 prevalent tunneled catheters were locked with citrate and prospectively followed during a 1‐year period. The primary endpoint was first CRB diagnosed according to two of the diagnostic criteria for Catheter Infection of Centers for Disease Control and Prevention (CDC), namely definite and probable infection. The CDC criterion of possible but not proved infection was not considered. This citrate lock cohort (n = 157) had 10 episodes of CRB. We observed 0.49 CRB episodes/1000 patient‐days and the mean infection‐free catheter day was 130.6 ± 100.9. No clinically relevant adverse events were observed. No proved tunnel or exit site infection was observed and no patients died because of CRB. Catheter obstruction episodes were reported on 69 occasions out of 14 catheters. These results were compared with an historical cohort from a previous study of catheter locking with low‐dose gentamicin and did not show significant difference in efficacy. Citrate lock is effective in preventing CRB. No toxicity was observed. The use of citrate lock may have advantages over antibiotic locks: No reported bacterial resistance, lower industrial cost, and less manipulation.     

Enterococcus faecalis endophthalmitis as a metastatic complication of hemodialysis vascular access‐related sepsis: A case report and review of the literature

Catheter and/or arteriovenous (A‐V) graft‐related bacteremia is an important cause of morbidity and mortality among hemodialysis (HD) patients. Endocarditis, septic arthritis, epidural abscess, septic embolism, and osteomyelitis are the most common complications of catheter and/or A‐V graft‐related bacteremia; however, endogenous endophthalmitis is rarely seen. To the best of our knowledge, Enterococcus faecalis is the first case report in this population. We hereby report a case of endogenous endophthalmitis caused by E. faecalis as a complication of catheter and/or A‐V graft‐related bacteremia in a diabetic patient, who was undergoing HD for 5 years. We also discuss the etiology, clinical features, and outcomes of endogenous endophthalmitis in HD patients with a brief review of the literature. Although broad‐spectrum parenteral (intravenous and intravitreal) antibiotics were used for 4 weeks, evisceration of the left eye could not be avoided. Endogenous endophthalmitis is a rare but rapidly blinding complication of catheter and/or A‐V graft‐related bacteremia in HD patients. It can develop as a result of silent catheter and/or A‐V graft infections, which may lead to recurrent bacteremia. E. faecalis should be considered as a pathogen in this population who had recent history of catheter or A‐V graft procedure.     

Antibiotic lock: In vitro stability of vancomycin and four percent sodium citrate stored in dialysis catheters at 37°C

Catheter-related bacteremia (CRB) is a major cause of morbidity and mortality especially among patients receiving hemodialysis (HD). Antibiotic lock therapy represents a promising technique in the treatment of CRB. Several studies have evaluated antibiotics in combination with heparin as an interdialytic locking solution as adjunctive therapy for CRB. The objective of this study was to evaluate the chemical stability of the vancomycin in 4% sodium citrate in HD catheters as an interdialytic lock. Vancomycin was prepared and diluted with sodium citrate 4% and stored in polyvinyl chloride syringes, 2 carbothane dialysis catheters (Hemostar^®) and 2 dual floating HD catheters (CardioMed^®). Syringes were stored at 4 °C or 23 °C and the catheters were stored in an incubator at 37 °C for 72 hours. Samples underwent daily chromatographic analysis and the luminal concentration of vancomycn was determined on study days 0, 1, and 3. When vancomycin is reconstituted with normal saline to achieve a concentration of 50 mg/mL, and then further diluted in 4% sodium citrate, to achieve concentrations of either 1 or 3 mg/mL, and then stored at 4 °C, room temperature, or 37 °C, solutions were observed to retain >92% of the initial concentration for the study period of 3 days. Based on the fastest degradation rate determined with 95% confidence interval, >90% is retained for 6.53 days. We conclude that vancomycin—4% citrate solutions stored in polyvinyl chloride syringes or HD catheters are not significantly affected by temperature or concentration within the 72 hours storage period. Therefore, these solutions can be anticipated to be suitable as a HD interdialytic antibiotic lock in standard HD catheters.     

Catheter‐related bacteremia and mortality in frequent nocturnal home hemodialysis

Frequent nightly home hemodialysis (NHHD) has emerged as an attractive alternative to thrice weekly in‐center hemodialysis, albeit with preponderant long‐term hemodialysis catheter used. Sixty‐three NHHD patients from University of Virginia Lynchburg Dialysis Facility were matched 1:2 with 121 conventional hemodialysis patients admitted to Fresenius Medical Care North America facilities from January 1, 2007 to December 31, 2010. Matching considered age (± 5 years), gender, race, dialysis vintage, and diabetes. The primary end‐point was the combined incidence of bacteremia/sepsis, for up to 20 months or upon changing to a fistula/graft (with catheter removal), transferring to peritoneal dialysis (PD), or at the time of kidney transplant or death. No significant differences were observed in rate of fistula/graft conversion, transfer to PD, transplant, or death between NHHD and in‐center hemodialysis (IHD) groups. For the first catheter used, the rate of catheter‐related sepsis was not significantly different between the NHHD (1.77 per 100 patient months) and IHD (2.03 per 100 patient months; P = 0.21). Combining all catheters, the rate of bacteremia/sepsis per 100 patient months in the NHHD group was 1.51 and in the IHD group was 2.01 (P = 0.35). Median catheter lifespan for the first catheter was 5.6 (1.7～19.0) for NHHD and 4.6 (2.7～7.8) for the IHD group (P = 0.64), and for all catheters used was 5.2 (Q1～Q3 = 1.5～15.2) months in NHHD group, and 4.1 (2.0～6.8) months in IHD group (P = 0.20). The rate of bacteremia and death is not different for up to 20 months in catheter users who dialyze via frequent NHHD vs. thrice weekly IHD.     

The CLOCK trial,a double‐blinded randomized controlled trial: Trisodium citrate 30% and minocycline 3 mg/mL plus EDTA 30 mg/mL are effective and safe for catheter patency maintenance among CKD 5D patients on hemodialysis

Introduction: Poor blood flow rate (PF) is highly prevalent among CKD 5D patients with long‐term central venous catheters. Heparin catheter lock solutions are commonly used to maintain catheter patency, however the incidence of PF remains high. The purpose of the CLOCK Trial was to evaluate two catheter lock solutions on reduction of PF incidence. Methods: Seventy‐five CKD 5D patients on high‐efficiency hemodialysis at the Integrated Centre of Nephrology (Guarulhos, Brazil) were randomized 1:1:1 to receive a lock solution combining minocycline 3 mg/mL with the anticoagulant/chelation agent EDTA 30 mg/mL (M‐EDTA) or heparin 1000 IU/mL (H) or trisodium citrate 30% (TSC) vs. Hfor 15 weeks. A total of 68 patients completed the trial in which both investigators and patients were blinded to treatment allocation. The primary end‐point was the occurrence of hydraulic resistance and secondary safety end‐point was adverse drug reactions related to the lock solutions. Findings: At the beginning of the trial, 7 patients were excluded from this trial due to their poor catheter care. The incidence of hydraulic resistance was significantly higher among patients on H (18/23) compared to TSC (4/22) and M‐EDTA (2/23) lock solutions, (P < 0.001). Discussion: The CLOCK Trial suggests TSC and M‐EDTA may preserve catheter patency better than H. TSC may be a better option due the lack of association with long‐term antimicrobial resistance.     

Chronic hepatitis C infection: Prevalance and effect on clinical status of hemodialysis patients in our center

Purpose:  Contamination of catheter hub connectors is known to cause catheter‐related blood stream infections in patients undergoing hemodialysis via central venous catheters (CVC). The effectiveness of cleansing the hub with an antimicrobial agent was assessed by culturing the surface of the hub following sanitation. Methods:  The CVC hub connectors of 24 patients were sanitized using the standard hospital protocol of aseptically swabbing the connectors with a solution of bleach or Betadine, and then bathing the hub in sterile gauze soaked with the antimicrobial solution for 5 minutes. The exterior surface of the hub was then cultured for a broad spectrum of microorganisms. Patients were monitored for exit site infection, tunnel infection, and septicemia. In the laboratory, sterile hubs were inoculated with E. coli , staph. aureus neg ., and yeast. Hubs were then immersed in Betadine for 5, 10, or 30 min. and cultures were taken. Results:  Positive cultures were obtained from the hubs of 17 of the 24 patients. Seven (7) of the patients with positive results developed bacteremia from the cultured organism within 7 weeks. Positive cultures were obtained from 50% of inoculated lab samples after 5 min, 10% after 15 min, and 0% after 30 min. of immersion sanitation. Conclusions:  The techniques for cleansing CVC hubs should be revisited.     

Inadvertent postdialysis anticoagulation due to heparin line locks

Large-bore dual lumen in-dwelling venous catheters are used in hemodialysis. These catheters are usually locked with heparin after the treatment. This study addressed the underappreciated postdialysis coagulopathy that can result. Thirty-six patients were included: 7 dialyzed through arterio-venous fistulae, 29 through in-dwelling venous catheters. The latter group was further subdivided according to whether they received heparin or heparin-free dialysis. To assess the heparin lock, a full-dose heparin lock as well as a much weaker heparin lock and a citrate lock were used. To assess the coagulopathy, blood was taken 1 hr after dialysis. The activated partial thromboplastin time (APTT) and anti-Xa level was measured. Additionally, 6 venous catheters were removed and the amount of fluid expelled upon locking with saline was measured. Clotting from the patient group with arterio-venous fistulae was normal following dialysis. The patients with in-dwelling venous catheters and heparin locks had significantly deranged clotting; 6 out of 10 patients had abnormal APTT results. All patients with catheters, heparin-free dialysis, and heparin locks had deranged clotting (7 out of 7). The rate decreased significantly when heparinized saline was used as a lock. A subset of patients had a citrate lock rather than a heparin lock; the clotting results normalized in all but one patient. An in vitro study demonstrated immediate leakage of fluid from the end of the ports upon locking. Significant postdialysis anticoagulation can occur after dialysis, which can be attributed to the heparin line locks. This risk is considerably reduced when a citrate lock is used instead.     

Six years of experience with nightly home hemodialysis access

Background: Lynchburg Nephrology Dialysis Incorporated started its nightly home hemodialysis (NHHD) program in September 1997. Purpose: The purpose of this study was to evaluate episodes of exit‐site infections, catheter sepsis, and safety and longevity of accesses for patients doing NHHD. Method: If internal jugular (IJ) catheter was chosen, the patient was started on 2 mg coumadin per day when catheter was placed. If catheter malfunctioned, it was blocked with a thrombolytic agent and coumadin was adjusted to meet a goal international normalized ratio (INR) of 1.5 to 2.25. If the problem persisted, the catheter was exchanged. For catheters, a threaded lock cannula (BD InterLink device, BD) was used to prevent air emboli and infections and a locking device was used to prevent disconnects. If arteriovenous (AV) fistula was used, four buttonholes were established using 16‐gauge needles. If AV graft was used, patients were taught the rope ladder cannulation technique using 16‐gauge needles. Results: As of September 1, 2003, 45 patients have completed training and have performed 27,063 treatments at home. Total catheter time at home was 930 months. Total AV fistula and AV graft times at home were 190 and 20 months, respectively. Upon completion of training, 34 patients were using tunneled IJ catheters, 10 were using AV fistulas, and 1 was using an AV graft. The IJ catheter exit‐site and sepsis infection rates were 0.35 and 0.52 episodes per 1000 patient‐days, respectively. Mean catheter life was 8.5 months with the longest being 66.7 months and the shortest being 0.2 months. The AV fistula and graft exit‐site and sepsis infection rates were 0.16 and 0 episodes per 1000 patient‐days, respectively. Catheter complications included one episode of disconnect due to patient's failure to use the locking device, one episode of central stenosis, and one episode of intracranial hemorrhage, due to prolonged INR, with resolution of symptoms. Conclusion: Data support the fact that tunneled IJ catheters, AV fistulas, and AV grafts are effective and safe permanent accesses for patients on NHHD.     

Prevention and Treatment of Thrombosis Associated With Long-Term Hemodialysis Catheters

Soft, cuffed, central vein hemodialysis catheters are used in about 20% of chronic hemodialysis patients in the United States, because long-term arteriovenous blood access cannot be maintained in an aging patient population with a large proportion of diabetics. The most frequent complication of these catheters is thrombosis. The treatment of catheter-related thrombosis is difficult and expensive; thus the emphasis should be on prevention. The preferred material for a long-term catheter is silicone rubber, since it is the least thombogenic. Anticoagulation should be more vigorous during “catheter dialysis” than during “fistula dialysis.” Heparin is the least expensive and most convenient anticoagulant, suitable for over 99% of chronic dialysis patients. The dose of heparin for sufficient anticoagulation depends on many factors, varies widely, and should be established for each patient based on activated clotting time (ACT). ACT should be kept over 270 sec throughout dialysis. Recently we introduced a method of locking catheter lumina with a predetermined amount of heparin; this heparin is not discarded before the next dialysis, but serves as a loading dose. This saves a number of connections/ disconnections and decreases dialysis-associated blood losses. To prevent catheter thrombosis, over 60% of patients require warfarin in sufficient doses to keep the international normalized ratio (INR) between 1.5 and 2.5. The most common catheter-related thrombus is a periluminal fibrin sleeve. Locking the catheter with urokinase to dissolve the clot is of little value, because the bulk of the thrombus is outside the catheter. We have found a high-dose (250 000 U or more) intradialytic urokinase infusion through the venous chamber to be a very efficient and convenient method for dissolving clots. Cumulative success of up to three infusions is over 99%. This obviates the need of catheter stripping or replacement, which is more cumbersome and expensive.     

Carriage of Staphylococcus aureus in the nose of patients on regular dialysis treatment using hemodialysis catheters

In the hemodialysis population, the incidence of Staphylococcus aureus colonization has been documented to be as high as 80%; effective prophylaxis of vascular access infection and bacteremia is a worthwhile goal in the management of hemodialysis population. Surveillance of 50 hemodialysis patients for S. aureus‐positive nasal cultures was performed by monthly nasal swabs over a 12‐month period. All patients were performing dialysis using hemodialysis catheters thrice weekly. All positive cultures were treated with a prophylactic antibiotic regimen. Thirty‐one patients (62%) had one or more positive cultures. The surveillance period was longer in the S. aureus nasal carriers (p < 0.01). The frequency of positive cultures correlated with the duration of surveillance (p < 0.05). The incidence of S. aureus bacteremia was greater in patients with three or more positive cultures (p < 0.05). This study suggests that continuous surveillance for S. aureus nasal colonization is essential to properly identify all hemodialysis patients using catheters at risk of developing S. aureus bacteremias.     

Tissue plasminogen activator as a hemodialysis catheter locking solution

Tunneled hemodialysis catheters require a "locking solution" between treatments to prevent catheter thrombosis. Heparin locks can be unsafe in patients with life-threatening bleeding diathesis because of unintentional anticoagulation. This study was designed to define the hematologic consequences of using tissue plasminogen activator (t-PA) as an alternative locking solution after heparin-free hemodialysis (HF-HD). Following HF-HD, t-PA 2 mg was instilled into each lumen of the dialysis catheter in 10 patients. Euglobulin clot lysis time (ECLT), fibrinogen, D-dimer, and fibrin degradation products were measured during the last hour of dialysis, and repeated 15 and 30 minutes after catheter locking. Dialysis catheter performance was reassessed at the time of the next hemodialysis. Fibrinogen, D-dimer, and fibrin degradation products were elevated at all time points, but did not change after t-PA. ECLT decreased significantly from baseline 15 minutes after catheter locking (217+/-64 vs. 132+/-75 min, p=0.016). ECLT values had returned to baseline (202+/-56 minutes) by 30 minutes. No episodes of bleeding or catheter thrombosis occurred, and catheter performance did not deteriorate. A 2 mg t-PA locking solution preserved dialysis catheter performance. ECLT decreased at 15 minutes, but normalized by 30 minutes, and did not enter the range in which bleeding would be likely. No clinical events were seen during this transient increase in systemic fibrinolysis.