Catheter Dysfunction: The Role of Lock Solutions

A Comprehensive Review of Catheter-Related Thrombosis

Catheter-related thrombosis (CRT) is a frequent and potentially serious complication associated with the widespread use of intravascular devices such as central venous catheters, including peripherally inserted central catheters and implantable port systems, pacemakers or implantable cardioverter-defibrillators. Although CRT management has been informed by guidelines extrapolated from lower extremity deep vein thrombosis (DVT), unique challenges remain due to the distinct anatomical, pathophysiological, and clinical characteristics of upper extremity DVT. Risk factors for CRT are multifactorial, encompassing patient-related characteristics such as cancer, prior venous thromboembolism, and infection, as well as catheter-specific factors like device type, lumens, and insertion site. The diagnosis of CRT relies primarily on ultrasonography; however, computed tomography angiography and magnetic resonance imaging play a complementary role, particularly in anatomically challenging cases or when complications such as pulmonary embolism or superior vena cava syndrome are suspected. Treatment strategies for CRT include anticoagulation, catheter removal when feasible, and, in select cases, local thrombolysis or catheter-directed interventions. Anticoagulation remains the cornerstone of therapy, with direct oral anticoagulants increasingly favored due to their safety profile and efficacy. This article provides a detailed review of CRT, focusing on clinical features, diagnostic methods, and treatment strategies while addressing specific challenges in managing pacemaker and hemodialysis catheter-related thrombosis.

Phyto-assisted synthesis of zinc oxide nanoparticles for developing antibiofilm surface coatings on central venous catheters

Medical devices such as Central Venous Catheters (CVCs), are routinely used in intensive and critical care settings. In the present scenario, incidences of Catheter-Related Blood Stream Infections (CRBSIs) pose a serious challenge. Despite considerable advancements in the antimicrobial therapy and material design of CVCs, clinicians continue to struggle with infection-related complications. These complications are often due colonization of bacteria on the surface of the medical devices, termed as biofilms, leading to infections. Biofilm formation is recognized as a critical virulence trait rendering infections chronic and difficult to treat even with 1,000x, the minimum inhibitory concentration (MIC) of antibiotics. Therefore, non-antibiotic-based solutions that prevent bacterial adhesion on medical devices are warranted. In our study, we report a novel and simple method to synthesize zinc oxide (ZnO) nanoparticles using ethanolic plant extracts of Eupatorium odoratum. We investigated its physio-chemical characteristics using Field Emission- Scanning Electron Microscopy and Energy dispersive X-Ray analysis, X-Ray Diffraction (XRD), Photoluminescence Spectroscopy, UV-Visible and Diffuse Reflectance spectroscopy, and Dynamic Light Scattering characterization methods. Hexagonal phase with wurtzite structure was confirmed using XRD with particle size of ∼50 nm. ZnO nanoparticles showed a band gap 3.25 eV. Photoluminescence spectra showed prominent peak corresponding to defects formed in the synthesized ZnO nanoparticles. Clinically relevant bacterial strains, viz., Proteus aeruginosa PAO1, Escherichia coli MTCC 119 and Staphylococcus aureus MTCC 7443 were treated with different concentrations of ZnO NPs. A concentration dependent increase in killing efficacy was observed with 99.99% killing at 500 μg/mL. Further, we coated the commercial CVCs using green synthesized ZnO NPs and evaluated it is in vitro antibiofilm efficacy using previously optimized in situ continuous flow model. The hydrophilic functionalized interface of CVC prevents biofilm formation by P. aeruginosa, E. coli and S. aureus. Based on our findings, we propose ZnO nanoparticles as a promising non-antibiotic-based preventive solutions to reduce the risk of central venous catheter-associated infections.

Pathology of catheter-related complications: what we need to know and what should be discovered

Despite the considerable efforts made to increase the prevalence of autogenous fistula in patients on hemodialysis, tunneled cuffed catheters are still an important access modality and used in a high percentage of the hemodialysis population. However, because of the conundrum posed by tunneled cuffed catheters, patients can develop a multitude of complications, including thrombosis, infections, formation of a fibrin sheath, and central vein stenosis, resulting in increased morbidity and mortality as well as placing a heavy burden on the healthcare system. However, with an increasing number of studies now focusing on how to manage these catheter-related complications, there has been less translational research on the pathology of these complications. This review of the most recent literature provides an update on the pathological aspects of catheter-related complications, highlighting what we need to know and what is yet to be discovered. The future research strategies and innovations needed to prevent these complications are also addressed.

Comparison of the Effect of Heparinized Normal Saline Solution Versus Saline Solutions in Arterial and Central Venous Catheters on Complete Blood Count After Cardiac Surgery

Background

Heparinized and saline solutions can prevent clot formation in arterial and central venous catheters. However, heparin can decrease the platelet count and induce thrombocytopenia. Patients undergoing cardiac surgeries are more likely to develop heparin-induced thrombocytopenia.

Objectives

This study aimed to investigate the effect of heparinized and saline solutions of arterial and central venous catheters on complete blood count (CBC) after cardiac surgery.

Methods

This randomized controlled trial was conducted on 100 participants. All subjects underwent cardiac surgery at Rajaie Cardiovascular, Medical, and Research Center, Tehran, Iran. Patients were randomly divided into two groups intervention (A) for whom heparinized normal saline solution was used to maintain central arterial and venous catheters, and control (B) for whom normal saline solution was used. The CBC of subjects was monitored for three days (before surgery and the first and second days after surgery).

Results

In the present study, there were no significant differences between CBC, white blood cell differential count, prothrombin time, partial thromboplastin time (PTT), and international normalized ratio in groups A and B. However, we found significant differences in platelet count (P = 0.049), red blood cell count (P = 0.0001), hemoglobin (P = 0.0001), and hematocrit (P = 0.0001) between before surgery and the second day after surgery in group A. Platelet count (P = 0.027) and PTT (P = 0.0001) before and after surgery were significantly different in group B.

Conclusions

According to the results of this study, normal saline solution catheters have fewer side effects and can be a suitable replacement for heparinized catheters.

Surface modification strategies for hemodialysis catheters to prevent catheter-related infections: A review

Insertion of a central venous catheter is one of the most common invasive procedures applied in hemodialysis therapy for end-stage renal disease. The most important complication of a central venous catheter is catheter-related infections that increase hospitalization and duration of intensive care unit stay, cost of treatment, mortality, and morbidity rates. Pathogenic microorganisms, such as, bacteria and fungi, enter the body from the catheter insertion site and the surface of the catheter can become colonized. The exopolysaccharide-based biofilms from bacterial colonies on the surface are the main challenge in the treatment of infections. Catheter lock solutions and systemic antibiotic treatment, which are commonly used in the treatment of hemodialysis catheter-related infections, are insufficient to prevent and terminate the infections and eventually the catheter needs to be replaced. The inadequacy of these approaches in termination and prevention of infection revealed the necessity of coating of hemodialysis catheters with bactericidal and/or antiadhesive agents. Silver compounds and nanoparticles, anticoagulants (e.g., heparin), antibiotics (e.g., gentamicin and chlorhexidine) are some of the agents used for this purpose. The effectiveness of few commercial hemodialysis catheters that were coated with antibacterial agents has been tested in clinical trials against catheter-related infections of pathogenic bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis with promising results. Novel biomedical materials and engineering techniques, such as, surface micro/nano patterning and the conjugation of antimicrobial peptides, enzymes, metallic cations, and hydrophilic polymers (e.g., poly [ethylene glycol]) on the surface, has been suggested recently.

Cefazolin-gentamicin versus taurolidine-citrate for the prevention of infection in tunneled central catheters in hemodialysis patients: A quasi-experimental trial

BACKGROUND

Catheter-related bloodstream infection (CR-BSI) is one of various complications related to hemodialysis (HD). As a result of the high rate of infection, the use of lock solutions for the prevention of CR-BSI has been studied. However, adverse effects of lock solution, such as increased emergence of strains resistant to antibiotics, which is an important concern, need to be investigated further. The aim of this study was to compare the efficacy of lock solution using a combination of cefazolin and gentamicin versus taurolidine and citrate in reducing CR-BSI in patients undergoing HD and to identify any adverse effects.

METHODS

A prospective observational study was performed at two dialysis centers. Patients using new tunneled central venous catheters (CVC) for HD were included. Patients with a tunneled CVC were assigned to receive either antibiotic lock solution (group 1: gentamicin 7mg/ml+cefazolin 12mg/ml+heparin 3500IU/ml) or lock solution with TauroLock-Hep500 (group 2: taurolidine citrate 4%+heparin 500 IU/ml) during the inter-dialysis period. The patients were allocated to these groups according to the hemodialysis center they were attending.

RESULTS

A total of 145 CVCs were implanted in 127 patients and were followed for 15 months: 77 CVCs (65 patients) were placed in group 1 and 68 CVCs (62 patients) in group 2. There was no difference between the two groups with regard to CR-BSI (events per 1000 catheter-days: group 1=0.79, group 2=1.10; p=0.18) or exit site infection rates (events per 1000 catheter-days: group 1=2.45, group 2=1.83; p=0.37). The groups differed in ESI pathogens, with gram-positive oxacillin-resistant pathogens more frequent in group 1 (31.8% vs. 5.0%; p=0.003). The two groups were similar in mechanical complications. In the Cox regression analysis, the internal jugular vein site was a protective factor for all catheter removal complications (hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.19-0.91) and mechanical complications (HR 0.16, 95% CI 0.065-0.41); only ESI was a risk factor for all catheter removal complications (HR 1.79, 95% CI 1.04-3.07) and mechanical complications (HR 5.64, 95% CI 1.65-19.3).

CONCLUSIONS

The efficacy of both lock solutions was similar in preventing infections related to tunneled CVCs for HD. However, there were more oxacillin-resistant strains in patients who received antibiotic lock solution. Further studies are required to determine the optimal drug regimen and concentrations for lock solution and the associated adverse effects.

Lipectomy Technique as a Second-stage Procedure for Primarily Matured, Deep Outflow Vein in Obese Individuals

Prevalence of obesity is growing in the general population as well as among end-stage renal disease (ESRD) patients requiring dialysis. Obesity often leads to a situation when a mature outflow vein is located deeper than 6 mm and is difficult to cannulate. These obese patients usually require additional procedures to able to successfully cannulate the fistula. The available surgical options include: outflow vein elevation, liposuction, and lipectomy. We present a case of a 57-year-old obese female with ESRD and matured, deeply running, inadequate for cannulation arteriovenous fistula. We present a technique of lipectomy with wide resection of adipose tissue from superior and lateral surfaces of outflow vein. Postoperatively, the skin without the underlying adipose tissue collapses allowing easy cannulation of the long segment of outflow vein with two needles. Lipectomy of mature but deeply located outflow vein is a second-stage elective procedure. Wide resection of adipose tissue helps create easy to access cannulation zone in obese individuals.

Comparison of Copper(II)-Ligand Complexes as Mediators for Preparing Electrochemically Modulated Nitric Oxide-Releasing Catheters

Further studies aimed at examining the activity of different Cu(II)-ligand complexes to serve as electron-transfer mediators to prepare novel antimicrobial/thromboresistant nitric oxide (NO)-releasing intravenous catheters are reported. In these devices, the NO release can be modulated by applying different potentials or currents to reduce the Cu(II)-complexes to Cu(I) species which then reduce nitrite ions into NO_(g) within a lumen of the catheter. Four different ligands are compared with respect to NO generation efficiency and stability over time using both single- and dual-lumen silicone rubber catheters: N-propanoate- N, N-bis(2-pyridylethyl)amine (BEPA-Pr), N-propanoate- N, N-bis(2-pyridylmethyl)amine (BMPA-Pr), 1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃TACN), and tris(2-pyridylmethyl)amine (TPMA). Of these, the Cu(II)BEPA-Pr and Cu(II)Me₃TACN complexes provide biomedically useful NO fluxes from the surface of the catheters, >2 × 10^-10 mol·min^-1·cm^-2, under conditions mimicking the bloodstream environment. Cu(II)Me₃TACN exhibits the best stability over time with a steady and continuous NO release observed for 8 d under a nitrogen atmosphere. Antimicrobial experiments conducted over 5 d with NO-releasing catheters turned "on" electrochemically for only 3 or 6 h each day revealed >2 logarithmic units in reduction of bacterial biofilm attached to the catheter surfaces. The use of optimal Cu(II)-ligand complexes within a lumen reservoir along with high levels of nitrite ions can potentially provide an effective method of preventing/decreasing the rate of infections caused by intravascular catheters.

Hemodialysis Catheter-related Infection: Prophylaxis, Diagnosis and Treatment

Purpose

Infectious complications associated with central venous catheters (CVCs) are a major source of morbidity and mortality among hemodialysis (HD) patients. This review aims to discuss prevention, diagnosis criteria and management of CVC-related infections in HD patients.

Methods

We searched Medline for articles published in the last 10 years, with the keywords “catheter,” “hemodialysis,” “infection,” “treatment,” “diagnosis,” “prophylaxis” and “adults.” Only English language articles were reviewed. We reviewed prophylaxis and surveillance protocols, diagnosis criteria, including new molecular tools, and the management of catheter-related infections, including antibiotic regimen, empiric and according to causal agents, lock therapy, catheter salvage or removal choice and treatment of complications.

Results

To prevent infectious complications, first of all we need to avoid using catheters. If we need CVC, adoption of prophylaxis and surveillance protocols, and antibiotic ointment at the exit site reduce infectious complications. The diagnosis of CVC-related infections should be made with drainage and/or blood cultures. Empiric systemic antibiotics should cover Gram-positive and -negative microorganisms, and final regimen should be based on culture results. In selected cases, salvage of site, by CVC exchange over wire, or salvage of catheter, using antibiotic lock, under the cover of systemic antibiotics, could be attempted.

Conclusions

The best approach to prevent CVC-related infection would be to avoid the use of CVC. However, in patients for whom it is impossible, the adoption of adequate prophylaxis protocols, early diagnosis and effective treatment of infectious complications are essential to improve outcomes.

Chemical stability of heparin, isopropanol, and ethanol line lock solutions

BACKGROUND

Ethanol line locks are used in the US to prevent catheter associated bloodstream infections. Heparin precipitates in solution with ethanol. However, isopropanol may reduce precipitate formation. We aimed to determine the chemical stability of heparin, isopropanol, and ethanol line lock for a 10 day period at 2-8°C and 25°C.

METHODS

Forty samples were prepared for analysis. Each sample was prepared identically using a 5 ml syringe capped with a Combi-stopper: 1 ml 70% isopropanol, 1 ml 70% ethanol, and 1 ml heparin sodium 10 IU/ml. Twenty syringes were stored at 2-8°C and 20 at 25°C. Analysis was carried out on days 1, 3, 6, 8, and 10 with a single syringe from each condition being tested in duplicate. Samples were assessed visually. Sub-visible particle count analysis was carried out using a CLIMET particle counting system. Heparin concentration was analysed using an anti-Xa assay. Ethanol and isopropanol concentrations were analysed by gas chromatography.

RESULTS

Samples remained clear and colourless throughout the study. Sub-visible particle counts remained within limits specified in British Pharmacopoeia 2013 when stored at 2-8°C and 25°C, 60% humidity for up to 10 days. There was no significant change in ethanol or isopropanol concentration during the study. However, heparin activity fell by >10% after 1 day storage and to 65% of original activity after 10 days.

CONCLUSIONS

This study shows that addition of isopropanol to heparin and ethanol prevents precipitation. However, this solution shows a progressive decline in heparin activity over time making it unsuitable for extended shelf life.

Prevention of hemodialysis catheter-related blood stream infections using a cotrimoxazole-lock technique

ABSTRACT 

Background & aim: This trial assessed the efficacy of cotrimoxazole lock solution in reducing catheter-related blood stream infections (CRBSIs) among hemodialysis (HD) patients who were dialyzed using tunneled catheters. Method: Patients randomly received either heparin (2500 U/ml) (control group) or a mixture of 10 mg/ml cotrimoxazole (based on trimethoprim) and 2500 U/ml heparin (antibiotic group) as catheters lock solution. Results: Compared with the control group, CRBSIs rates per 1000 catheter-days was significantly lower (0.58 vs 4.4 events; p = 0.002) and cumulative infection-free catheter survival was significantly higher (log rank statistic 5.88; p = 0.015) in the antibiotic group. There were no statistical differences regarding incidences of catheter removal (8.7% in the antibiotic group vs 22% in the control group; p = 0.116) or thrombosis (2.2% in the antibiotic group vs 9.8% in the control group; p = 0.129) between the two groups. Conclusion: cotrimoxazole containing catheter lock solution is effective in reducing CRBSIs incidence and prolonging dialysis catheter survival in HD patients.

Hemodialysis catheter locking solutions and the prevention of catheter dysfunction: a meta-analysis

PURPOSE

Tunneled dialysis catheters (TDCs) continue to be utilized at an alarming rate despite having a higher rate of complications when compared to fistulas and grafts. One of the primary complications of TDCs involves catheter dysfunction resulting in reduced blood flow and poor dialysis adequacy, often requiring catheter removal in addition to thrombolytic therapy. Our objective was to compare the use of locking solutions containing heparin versus all other locking solutions for primary prevention of TDC dysfunction.

METHODS

We searched Medline for English language literature from 1980 through December 2013, along with national conference proceedings and reference lists of all included publications to identify relevant studies. Inclusion criteria were a measure of incidence of catheter dysfunction, catheter exchange or use of thrombolytic therapy. Studies were excluded if they were not in English or if they included pediatric patients. Random effects models were used to derive the pooled risk ratios.

RESULTS

Thirteen studies with a total of 1,883 subjects met the inclusion criteria. There was no significant difference in catheter patency in those receiving heparin versus those treated with other lock solutions (incidence rate ratio [IRR] 0.99; 95% confidence interval [CI] 0.66-1.48, p = 0.96). Catheter patency did not differ between treatments in experimental studies (n = 10; IRR = 0.89; 95% CI: 0.56-1.39, p = 0.60) or observational design (n = 3; IRR = 1.64; 95% CI 0.40-6.85, p = 0.50). Significant heterogeneity was detected across studies (I2 = 84.4%, p<0.001).

CONCLUSIONS

Our results suggest that there is no substantial difference between heparin lock solutions versus all other types of catheter lock solutions for catheter dysfunction. Whether there are significant benefits of citrate or other novel lock solutions requires further robust studies. These findings have significant implications for future design of clinical trials in TDCs and the delivery of dialysis-related services.

Ethanol causes protein precipitation--new safety issues for catheter locking techniques

OBJECTIVE

The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions.

METHODS

Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation.

RESULTS

Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation.

CONCLUSIONS

Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions.

Successful prevention of tunneled central catheter infection by antibiotic lock therapy using cefazolin and gentamicin

Catheter-related bacteremia (CRB) is one of the various complications related to hemodialysis (HD). As a result of this high rate of infection, the antibiotic lock technique (ALT) has been recommended to prevent CRB. However, adverse effects of ALT such as increased emergence of strains resistant to antibiotics and increased mechanical dysfunction catheter were poorly evaluated. We prospectively evaluated the efficacy of catheter-restricted filling using an antibiotic lock solution in preventing CRB. A total of 233 HD patients requiring 325 new tunneled catheters while waiting for placement and maturation of an arteriovenous fistula or graft were enrolled in this study. Patients with a tunneled catheter were assigned to receive either an antibiotic-heparin lock solution (antibiotic group: cefazolin 10 mg/ml, gentamicin 5 mg/ml, heparin 1,000 U/ml) or a heparin lock solution (no-antibiotic group: heparin 1,000 U/ml) as a catheter lock solution during the interdialytic period. The present study aimed to assess the efficacy of ALT using cefazolin and gentamicin in reducing CRB in patients undergoing HD with tunneled central catheter and to identify its adverse effects. CRB developed in 32.4 % of patients in the no-antibiotic group and in 13.1 % of patients in the antibiotic group. CRB rates per 1,000 catheter-days were 0.57 in the antibiotic group versus 1.74 in the no-antibiotic group (p < 0.0001). Kaplan-Meier analysis also showed that mean CRB-free catheter survival was significantly higher in the antibiotic group than in the no-antibiotic group (log-rank statistic 17.62, p < 0.0001). There was statistically significant difference between the two groups in causative organisms of CRB, with predominance of negative culture in both groups, but this prevalence was higher in ALT group (57.9 vs 90.1 %, p < 0.0001), and the two groups also were different in prevalence of gram-positive bacteria as causing organisms (ALT group 21.05 vs = 0 % in control group, p < 0.0001). There was no statistically significant difference between the two groups in drug-resistant germs. There were statistically significant differences between the two groups in the catheter removal causes, with higher rate of infectious cause in control group (12.32 vs 2.22 %, p < 0.0001) and mechanical cause in ALT group (28.26 vs 37.78 %, p < 0.0001). The results suggest that ALT may be a beneficial means of reducing the CRB rate in HD patients with tunneled catheter, without association between ALT and emergence of strains resistant. However, mechanical complications were more prevalent in antibiotic group. Further studies are required to determine the optimal drug regimen, concentrations for ALT, and its adverse effects.