Tunneled Hemodialysis Catheters Research Articles

Misplacement of Tunneled Hemodialysis Catheter into Azygos Vein: Left or Right Jugular Insertion Has Similar Susceptibility

Background: Central venous catheter (CVC) is commonly used to provide access for hemodialysis (HD) when arteriovenous access is not available. The misplacement of CVC into azygos vein (AV) is a rare but a potential serious complication. Previous reports communicated the opinion that left-sided catheterization predisposed to AV misplacement, but these reports concentrated on peripherally inserted CVCs, placed for indications rather than HD. Unintended AV misplacement of HD catheters (HDCs) has not been well studied. We seek to investigate factors associated with inadvertent AV miscannulation during HDC placement. Methods: We are to present a case of unintentional misplacement of a tunneled HD catheter (tHDC) into the azygos arch from right internal jugular vein (RIJV) despite real-time fluoroscopy guidance. Additionally, we have undertaken a systematic literature search in Pubmed to study the anatomical and other factors related to unintended AV misposition in HD setting. Results: From 2005 to August 31, 2018, a total of 11 articles containing 16 cases of misplacement of HDCs into AV were identified. Of the 17 cases of unintentional AV misposition including ours, the majority of the misguided HDCs (94.1%, 16/17) were tHDCs and only 1 case was related to a temporary (non-tunneled) catheter. Most catheter misplacements (88.2%, 15/17) were performed without real-time radiological guidance. The reported incidence of inadvertent AV cannulation from different institutions varied between 0.6% and 3.8%. Among the 16 misplaced tHDCs, the rates of AV misposition that arose from RIJV and left internal jugular vein (LIJV) insertion are even at 50%. Conclusions: Based upon anatomical and case studies, we have found that AV may join posterior aspect of superior vena cava at different directions and levels. Hence, this might explain why AV misplacement might occur whether an HDC is inserted from the LIJV or RIJV approach. By raising the awareness of this potential complication and how we may minimize it, we hope to reduce the future complication of AV misposition.

Vascular Access Types and Outcomes Vary Significantly by Race and Ethnicity

To determine the association of race/ethnicity with initial vascular access type, time to removal of tunneled hemodialysis catheter(THC), probability of repeat vascular access and time to repeat vascular access.

Complications From Tunneled Hemodialysis Catheters: A Canadian Observational Cohort Study

Clinical practice guidelines discourage the use of central venous catheters (CVCs) for vascular access in dialysis. However, some patients have inadequate vessels for arteriovenous fistula creation or choose to use a dialysis catheter. The risks associated with CVC use and their relationship to patient age are poorly characterized. Observational retrospective cohort study. Cohort of 1,041 patients older than 18 years from 5 Canadian dialysis programs who initiated outpatient maintenance hemodialysis therapy with a tunneled CVC between 2004 and 2012 and who had no creation of an arteriovenous fistula or arteriovenous graft. Age, sex, body size, initiating dialysis therapy in the hospital, and comorbid conditions. CVC-related procedures, hospitalization, and death. Complications were reported as a cumulative risk at 1 and 2 years. Cox proportional hazards regression for recurrent events was used to evaluate risk factors for study outcomes. At 1 year, risks for CVC-related bacteremia, malfunction, and central stenosis were 9%, 15%, and 2%, respectively. Risks for any CVC-related complication at 1 and 2 years were 30% and 38%, respectively. Death related to CVC complications occurred in 6 of 1,041 (0.5%) patients. Compared with patients younger than 60 years, patients aged 70 to 79 and those 80 years or older experienced lower rates of CVC complications: HRs of 0.67 (95% CI, 0.52-0.85; P= 0.001) and 0.69 (95% CI, 0.52-0.92; P= 0.01), respectively. This Canadian dialysis population may not be representative of populations in other countries. CVC use was not compared with other types of hemodialysis vascular access. Approximately one-third of hemodialysis patients who used tunneled CVCs during 1 to 2 years experienced complications. Bacteremia occurred in ∼9% of patients at 1 year and were the most common cause of CVC-related hospitalizations. CVC-related death was infrequent. This information could be used to communicate the risk for CVC complications to patients treated with this type of hemodialysis vascular access.

Tunneled hemodialysis catheter placement in persistent left superior vena cava: A rare but potential hemodialysis vascular access

Persistent left superior vena cava (PLSVC) is a common congenital thoracic venous anomaly. Asymptomatic cases are often diagnosed incidentally during invasive cardiovascular procedures such as the placement of central venous access catheters. It is important for the physicians to be aware of clinical implications that may occur during catheter placement. We describe our experience with PLSVC during the placement of a tunneled hemodialysis (HD) catheter (permcath) through the left internal jugular venous route. The diagnosis was confirmed by contrast-enhanced computed tomography. PLSVC can be a potential site for HD catheter placement.

Patency and outcomes of tunneled hemodialysis catheter via femoral versus jugular vein access.

The design of a suitable catheter to achieve a permanent, economical, and efficient vascular pathway for hemodialysis has been always accompanied by difficult and potential complications. Various strategies have been adopted to minimize the use of tunneled catheters that are used for dialysis. Regarding this, the present study aimed to assess the success, patency, as well as early and late complications of cuffed femoral and jugular hemodialysis catheters. This case–control study was performed on 145 hemodialysis patients who were candidates for the insertion of tunneled hemodialysis catheters at Rasoul-e-Akram Hospital in Tehran, Iran, during 2015–2016. The data were collected retrospectively by reviewing the patients' medical records. The participants were divided into two groups of femoral and jugular accesses, based on the type of catheter they had. To determine the procedure-related outcomes, they were assessed 1 week, 1 month, and 6 months after catheterization. According to the results, the mean times of catheter efficacy (patency) were 4.43 ± 3.11 and 5.65 ± 4.57 months in the femoral and jugular access groups, respectively, showing no significant difference between the two groups (P = 0.095). Furthermore, the femoral and jugular access groups had the infection prevalence of 23.2% and 16.2%, thrombosis prevalence of 28.6% and 20.9%, and mortality rates of 3.5% and 1.4%, respectively. According to the multivariable linear regression model, the history of catheterization could predict reduced catheter patency. In addition, catheter-related infection could be predicted among females based on the multivariate logistic regression analysis. As the findings indicated, femoral and jugular hemodialysis catheter insertions showed no significant difference in terms of the mean patency, complications (e.g., infection and thrombosis), and mortality rate.

Haemodialysis vascular access function in dialysis patients at the Kenyatta National Hospital

Background: The number of patients requiring renal replacement therapy (RRT) worldwide has been on the rise. Vascular access is the lifeline for these patients when haemodialysis (HD) is the treatment of choice. Access-related morbidity is a leading cause of hospitalization so that the function and patency of access are essential for the optimal management of patients. There is a need to recognize when a vascular access is dysfunctional because intervention must maintain function as well as preserve future vascular access sites. Methods: This was a cross-sectional study that evaluated the haemodialysis vascular access function in patients undergoing chronic haemodialysis at the Kenyatta National Hospital, Nairobi, Kenya. Peak access blood flow rates, urea reduction ratio (URR) and Kt/V were analysed in 150 patients.Results: The temporary (non-tunnelled) central venous dialysis catheters had poor function, with only 48% achieving a mean blood flow rate > 300 mL/min. The comparable rate for arteriovenous fistulae (AVF) was 88% and for tunnelled dialysis catheters 82%. One-quarter of the patients had a URR < 65%. Higher mean blood flow rates were associated with higher URR (P = 0.004) and Kt/V (P = 0.009) values. AVF stenosis was present in 12.5% and thrombosis in 3% of patients. Aneurysms were the commonest AVF complication (47%) but were not haemodynamically significant. Conclusions: Tunnelled haemodialysis catheters offered adequate blood flows and achieved adequate delivered dialysis, comparable to arteriovenous fistulae. Non-tunnelled catheters delivered poor blood flow rates and dialysis dose. Greater blood flow rates were associated with a higher delivered dialysis dose. There is a need for routine surveillance and affordable interventional procedures to prevent loss of vascular access.

An analysis of potential predictors of tunneled hemodialysis catheter infection or dysfunction

To assess the ability of various clinical factors to predict infection or dysfunction of tunneled hemodialysis catheters. A retrospective review of all adult patients who had a tunneled hemodialysis catheter placed between 2012 and 2016 was performed. Tunneled hemodialysis catheters were considered infected based on clinical suspicion or culture-positive bacteremia. Dysfunction was defined as all other non-infectious causes for line failure. Time-to-removal or exchange was recorded. Clinical parameters analyzed as potential predictors of tunneled hemodialysis catheter infection or dysfunction, included the following: age, sex, site of placement, inpatient versus outpatient status at time of placement, body mass index, Charlson Comorbidity Index, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, platelet count, white blood cell count, international normalized ratio, and partial thromboplastin time. A total of 177 patients (95: female, 82: male; 71.7%: African American; mean age: 54.9 years) qualified for inclusion. The internal jugular vein was the site of placement in 97.1% of patients with 79.7% of lines being placed on the right side. One patient (0.5%) had minor bleeding after catheter insertion but no other complications were recorded. A total of 17 patients (9.6%) had lines removed or exchanged due to infection at a median of 86 (range: 13-626) days, while 68 patients (38.4%) had lines removed or exchanged due to dysfunction at a median of 42 (range: 1-531) days. A total of 92 patients (51.9%) had lines removed due to completion of therapy at a median of 68 (range: 7-433) days. Dysfunctional lines had a shorter time-to-removal than successful lines (p = 0.007). No difference was seen in time-to-removal between infected lines and successful lines (p = 0.16). Multivariate analysis showed that female sex (p = 0.003) and left-sided line placement (p = 0.007) were independent predictors of line dysfunction. No evaluated factors were predictive of tunneled hemodialysis catheter infection. Female sex and left-sided line placement were independent predictors of tunneled hemodialysis catheter dysfunction, but none of the evaluated parameters predicted tunneled hemodialysis catheter infection.

Agitated saline bubble-enhanced ultrasound for the positioning of cuffed, tunneled dialysis catheters in patients with end-stage renal disease.

In patients with end-stage renal disease, the use of cuffed, tunneled dialysis catheters for hemodialysis has become integral to treatment plans. Fluoroscopy is a widely accepted method for the insertion and positioning of cuffed dialysis catheters, because it is easy to use, accurate and reliable, and has a relatively low incidence of complications. The purpose of our study was to evaluate the feasibility of tunneled hemodialysis catheter placement without the use of fluoroscopy but with a dynamic ultrasound-imaging-based guided technique. From January 2015 to December 2017, we performed an observational prospective cohort study of 56 patients with end-stage renal disease who required tunneled dialysis catheter placement. The overall success rate for ultrasound-guided central access was 100%, with a mean number of 1.16 (±0.4) attempts per patient. There were no incidences of guide wire coiling/kinking, carotid puncture, pneumothorax, or catheter malfunction. Catheter flow during dialysis was 286 (±38) mL/min. The total number of catheter days was 7451, with a mean of 133 days and a range of 46-322 days. Life table analysis revealed primary patency rates of 100%, 96%, and 53% at 30, 60, and 120 days, respectively. Dynamic ultrasound-based visualization of microbubbles in the right atrium is a highly accurate method to detect percutaneous implantation of large-lumen, tunneled, central venous catheters without the need for fluoroscopic guidance technology. Future research should further develop and confirm these initial findings.

Regional anesthesia with epinephrine-containing lidocaine reduces pericatheter bleeding after tunneled hemodialysis catheter placement.

Pericatheter bleeding (PB) following tunneled hemodialysis catheter (THC) placement is a common phenomenon. In addition to complicating securement of the THC, the PB may loosen the adhesive catheter dressing and delay wound healing. The primary aim of this study was to determine whether epinephrine-containing local anesthetics rather than plain ones reduce superficial PB after THC placement. The study was based on the retrospective analysis of the prospectively gathered data. Forty-six patients receiving local analgesia during THC placement were randomly assigned in a double-blind manner to two groups according to local anesthetic mixtures used (n =22 to prilocaine group [group 1]; n =24 to epinephrine-containing lidocaine group [group 2]). Presence or absence of PB after the THC placement was evaluated. Differences between groups with and without controlling other variables were statistically analyzed. Epinephrine-containing lidocaine (group 2) significantly reduced PB in comparison with prilocaine, P = 0.003. Use of epinephrine-containing lidocaine (group 2) was associated with a reduction in the likelihood of PB (Odds ratio = 0.017). Meanwhile, use of prilocaine (group 1) had 59.7 times higher odds in the likelihood of PB after THC placement. Lower rate of systolic blood pressure (SBP) in group 2 patients after 5 minutes of injections was also noted, P = 0.008. Epinephrine-containing lidocaine was well tolerated and caused no significant cardiovascular disturbance. Local infiltration of epinephrine-containing lidocaine instead of plain local anesthetics during THC insertion may reduce superficial PB and improve patient comfort.

Outcomes of Hemodialysis Vascular Access in Patients Initiating Dialysis With a Tunneled Catheter

The objective of this study was to determine factors that influence time to removal of tunneled hemodialysis catheter (THC), probability of repeated vascular access creation, and time to repeated vascular access. The Optum (Eden Prairie, Minn) Clinformatics database, which contains claims from a large managed care organization, from 2011 to 2016 was queried for patients who initiated hemodialysis with a THC. Time from initial arteriovenous fistula (AVF) or arteriovenous graft (AVG) to THC removal and time to repeated AVF or AVG were analyzed using Cox proportional hazards. Multivariate models included age, sex, race, diabetes, cardiac arrhythmia, congestive heart failure, peripheral vascular disease, and obesity as covariates. There were 8355 vascular accesses that met the inclusion criteria 6648 (77%) AVFs and 1940 (23%) AVGs. Median follow-up was 424 days (range, 1-2097 days). Patients undergoing AVF were younger and more likely to be male and white (Table). At 90 days, 20.3% (95% confidence interval [CI], 19.3%-20.3%) of AVFs vs 56% (95% CI, 53.7%-58.4%) of AVGs had the THC removed. At 180 days, 56.7% (95% CI, 55.4%-58.1%) of AVFs vs 68.4% (95% CI, 66.1%-70.6%) of AVGs had the THC removed. By day 315, 74% of patients with both AVFs and AVGs had the THC removed. Multivariate analysis demonstrated a significant interaction between vascular access type and age ≥70 years (P < .001). In the age group <70 years, patients who underwent AVG had a THC removal rate 46% higher than that of patients who underwent AVF. In the age group ≥70 years, patients who underwent AVG had a THC removal rate 88% higher than that of patients who underwent AVF. There were 1982 (23.7%) patients who underwent a second vascular access. Multivariate analysis demonstrated that AVG vs AVF (odds ratio, 0.70; 95% CI, 0.61-0.81) and age ≥70 years vs <70 years (odds ratio, 0.87; 95% CI, 0.78-0.98) were associated with a lower odds of second access. In patients who underwent a second access, multivariate analysis demonstrated that initial AVG was associated with longer time to second access (hazard ratio, 0.60; 95% CI, 0.54-0.68). Creation of AVG vs AVF significantly decreased the time to THC removal in dialysis-dependent patients, with a larger difference in patients aged ≥70 years vs <70 years. Initial AVG was associated with lower odds of second access and longer time to second access in those who underwent second access. These results contradict the dictum of “fistula first” and support the judicious use of AVG in achieving the more recent shift toward “catheter last.”TableDemographics by access typeFistula (n = 6486), No. (%)Graft (n = 1869), No. (%)P valueAge, years mean (SD)66.2 (13)69 (12)<.001Age ≥70 years2979 (46)1028 (55)<.001Male3920 (60)811 (44)<.001Race<.001 Asian216 (3)51 (3) Black1586 (24)677 (36) Hispanic859 (13)192 (10) White3663 (56)915 (49) Unknown168 (3)28 (1)Diabetes5257 (81)1565 (84).001Cardiac arrhythmia4688 (72)1400 (75).13Congestive heart failure5021 (77)1480 (79).073Peripheral vascular disease4406 (68)1322 (71).011Obesity2596 (40)694 (37).03SD, Standard deviation. Open table in a new tab

Outcome of radiologically placed tunneled haemodialysis catheters.

To study the outcome of radiologically placed double lumen tunneled haemodialysis catheters for the management of renal failure. Case series. Interventional Suite of Radiology Department at the Aga Khan University Hospital, Karachi, from April 2010 to June 2011. All consecutive patients who were referred to the department of radiology by the nephrologists for double lumen tunneled haemodialysis catheter (Permacath) placement during the study period were included. Patients with septicemia, those for whom follow-up was not available, those coming for catheter exchange or who died due to a noncatheter related condition were excluded. A radio-opaque, soft silicone double lumen catheter was inserted through a subcutaneous tunnel created over the anterior chest wall. The catheter tip was placed in the right atrium via the internal jugular vein. Ultrasound guidance was used for initial venous puncture. The rest of the procedure was carried out under fluoroscopic guidance. Technical success, catheter related bacteremia rates, adequacy of dialysis, patency, and adverse events were analyzed. Overall 88 tunneled haemodialysis catheters were placed in 87 patients. Patients were followed-up for duration of 1 - 307 days with mean follow-up period of 4 months. Immediate technical success was 100%. The procedural complication rate was 5.6% (5 catheters). Eight patients died during the study period, seven from causes unrelated to the procedure. One patient died due to septicemia secondary to catheter related infection. Of the remaining 69 patients, 50 (72.4%) predominantly had uneventful course during the study period. Twelve patients developed infection (17.3%); two were successfully treated conservatively while in 10 patients catheter had to be removed. Seven catheters (10.1%) failed due to mechanical problems. In 3 patients the internal jugular veins got partially thrombosed. One catheter was accidentally damaged in the ward and had to be removed. Radiological guided tunneled haemodialysis catheter placements are a safe and reasonable means of providing temporary vascular access for haemodialysis patients.

Diagnostic and Interventional Nephrology in Spain: A snapshot of current situation.

Diagnostic and Interventional Nephrology has been a rising field in recent years worldwide. Catheter insertion, renal biopsy, renal ultrasound, and peritoneal dialysis catheter or permanent dialysis catheter insertion are vital to our specialty. At present, many of these procedures are delegated to other specialties, generating long waiting lists and limiting diagnosis and treatment. An online survey was emailed to all Nephrology departments in Spain. One survey response was allowed per center. Of 195 Nephrology departments, 70 responded (35.8%). Of them, 72.3% (52) had ultrasound equipment, 77.1% insert temporary jugular catheters, and 92.8% femoral. Up to 75.7% (53 centers) perform native renal biopsies, of which 35.8% (19) are real-time ultrasound guided by nephrologists. Transplant kidney biopsies are done in 26 centers, of which 46.1% (12) by nephrologists. Tunneled hemodialysis catheters are inserted in 27 centers (38.5%), peritoneal catheter insertion in 18 (31.6%), and only 2 centers (2.8%) perform arteriovenous fistulae angioplasty. In terms of ultrasound imaging, 20 centers (28.5%) do native renal ultrasound and 16 (22.8%) transplanted kidneys. Of all units 71.4% offer carotid ultrasound to evaluate cardiovascular risk, only in 15 centers (21%) by nephrologists. AVF ultrasound scanning is done in 55.7% (39). Diagnostic and Interventional Nephrology is slowly spreading in Spain. It includes basic techniques to our specialty, allowing nephrologists to be more independent, efficient, and reducing waiting times and costs, overall improving patient care. Nowadays, more nephrologists aim to perform them. Therefore, appropriate training on different techniques should be warranted, implementing an official certification and teaching programs.

Availability of right femoral vein as a route for tunneled hemodialysis catheterization.

PurposeThis study was performed to investigate the primary patency rate and catheter-related problems associated with use of the femoral vein as a route for tunneled hemodialysis catheterization compared with those of the right internal jugular vein as the first-choice route in patients undergoing maintenance hemodialysis.Patients and methodsTwenty-two patients underwent placement of indwelling tunneled hemodialysis catheters in the right internal jugular vein as the first option for maintenance hemodialysis, and 20 patients underwent placement in the right femoral vein as the second option. The primary patency rate of the catheters and catheter-related problems at 1, 3, 6, and 12 months after placement were investigated.ResultsThe 1-, 3-, 6-, and 12-month primary patency rates of the tunneled hemodialysis catheters in the right internal jugular vein were 95.5%, 95.5%, 81.3%, and 58.3%. The primary patency rates of the catheters in the right femoral vein were 95.0%, 89.5%, 86.7%, and 66.7%. There were no statistically significant differences in the primary patency rates at 1, 3, 6, and 12 months or in catheter-related problems between the right internal jugular vein and right femoral vein.ConclusionThe primary patency rate and catheter-related problems of indwelling tunneled hemodialysis catheters placed in the right femoral vein were not different from those in the right internal jugular vein in patients undergoing maintenance hemodialysis. These results suggest that the right femoral vein might be a useful option for placement of indwelling tunneled hemodialysis catheters in patients undergoing maintenance hemodialysis.

Prevalence of Central Vein Stenosis in Patients Referred for Vein Mapping.

Central vein stenosis is considered to be common in patients on hemodialysis but its exact prevalence is not known. In this study, we report the prevalence of central vein stenosis in patients with CKD referred for vein mapping. We conducted a retrospective study of adult patients who had bilateral upper extremity venographic vein mapping from September 1, 2011 to December 31, 2015. Patients with and without stenosis were compared for differences in clinical or demographic characteristics. Multiple logistic regression was used to identify independent associations between patient characteristics and central vein stenosis. There were 525 patients who underwent venographic vein mapping during the study period, 27% of whom were referred before initiation of hemodialysis. The mean age (±SD) and body mass index were 59 (±15) years and 28 (±7), respectively. Women accounted for 45% of patients; 82% were black. The prevalence of central vein stenosis was 10% (95% confidence interval [95% CI], 8% to 13%) for the whole group, and 13% (95% CI, 10% to 17%) among patients with tunneled central venous dialysis catheters. Current use of tunneled hemodialysis catheters (odds ratio [OR], 14.5; 95% CI, 3.25 to 65.1), presence of cardiac rhythm devices (OR, 5.07; 95% CI, 1.82 to 14.11), previous history of fistula or graft (OR, 3.28; 95% CI, 1.58 to 6.7), and history of previous kidney transplant (OR, 18; 95% CI, 4.7 to 68.8) were independently associated with central vein stenosis. In this population, the prevalence of central vein stenosis was 10% and was clustered among those with tunneled hemodialysis catheters, cardiac rhythm device, and previous history of dialysis access or transplant.

The development of central venous thrombosis in hemodialyzed patients is associated with catheter tip depth and localization.

The aim of our work was to analyze the incidence of tunneled hemodialysis catheters-related thrombosis in hemodialyzed patients depending on catheter tip depth and position and to evaluate the impact of other established risk factors responsible for development of central venous thrombosis. The presence of central vein thrombosis, location, and the depth of the catheter tip was reviewed by two experienced radiologists. All patients with suspected central venous thrombosis had factor V Leiden, lupus anticoagulant, and cardiolipin antibodies checked (acIgM and acIgG) and were evaluated with cat-scan venography. A total of 68 tunneled hemodialysis catheters were analyzed with CT venography for central venous thrombosis. There were no signs of central venous thrombosis when catheter tips were placed in the right atrium. There was significantly higher number of catheter tips located on the vein wall than located centrally in patients with central venous thrombosis. Higher percentage of central venous thrombosis, smaller number of tips placed in the right atrium, higher values of IgM cardiolipin antibodies, and higher number of patients with positive factor V Leiden mutation were found in group of patients with catheter tips located on vein wall. Higher incidence of central venous thrombosis in patients with the catheter tip placed on the vein wall is a consequence of a catheter tip depth proximal of the right atrium. Increased factor V Leiden mutation and acIgM values in these patients should be observed as a result of the vein stasis caused by inappropriate catheter tip depth and localization.

Unanticipated late maturation of an arteriovenous fistula after creation of separate graft access.

Autogenous arteriovenous vascular access with an arteriovenous fistula (AVF) is the gold standard for attaining long-term hemodialysis vascular access (1). When compared to prosthetic arteriovenous grafts (AVGs) and tunneled hemodialysis catheters, an AVF has less frequent rates of thrombosis, stenosis, and infection.

Failure to place a tunneled hemodialysis catheter due to malformation of right internal jugular vein draining to subclavian vein.

The right internal jugular vein (IJV) is an important access site for hemodialysis catheterization. Venous cannulation failure is usually caused by central venous stenosis and is rarely related to vessel malformation. We herein present a case of failure to place a tunneled hemodialysis catheter into the right IJV. The patient had an arteriovenous fistula in the right arm with inadequate flow and a history of multiple central venous catheterizations. The guidewire was repeatedly misplaced into the right subclavian vein (SV) regardless of the technique used. Computed tomography venography revealed that the inferior segment of the right IJV drained into the ipsilateral SV. To the best of our knowledge, this is the first report of catheterization failure due to abnormal drainage of the right IJV into the ipsilateral SV.

Early Flow Disturbances of Tunnelled Haemodialysis Catheters and Topographic Landmarks in Chest X-Ray

Background/Aims: The position of the tip of tunnelled haemodialysis (HD) catheters (THC) might influence flow characteristics during HD. In chest X-ray (CXR), carina-related landmarks may be practicable to verify the THC position, and tip-carina distance (TCD) might be useful to predict early-flow dysfunctions. Methods: In this single-centre, retrospective study, the TCD and the angle between the distal catheter and the body vertical axis (tip-body vertical-angle [TVA]) was measured in 115 THC by post-procedure CXR with 2 investigators. The parameters were proved to be feasible by interrater-reliability and correlated with the incidence of flow-dysfunction within 10 days after insertion. Results: Steep-aligned (TVA <40°, p < 0.01) and deep-ending catheters (TCD: right-sighted >1.5 cm or left-sighted >4.5 cm below the carina; p < 0.01) showed a significantly less dysfunction with a good interrater-reliability (R[TVA] = 0.8, R[TCD] = 0.9). Conclusions: Carina-related landmarks in CXR might be helpful to predict early-flow dysfunctions. However, randomized studies will be necessary to confirm this in fluoroscopic-guided placement during the insertion of THC.

Location and structure of fibrous sheath formed after placing a tunneled hemodialysis catheter in a large pig model

We evaluated the location and structure of the fibrous sheath formed after the placement of tunneled, cuffed hemodialysis catheters in large animals, 70 kg pigs. We focused on describing the location of the fibrous sheath in relation to the catheter. Its location explains the fibrous sheath's ability to cause catheter dysfunction by covering the catheter exit ports located at the catheter's tip. We used three animals. Each animal had a tunneled, cuffed, 15-French diameter hemodialysis catheter placed in the external jugular vein, with the tip at the junction of the superior vena cava and the right atrium. Two animals were sacrificed at 5 weeks and one animal at 17 weeks after catheter placement. The catheter and surrounding tissues were removed in one block. The fibrous sheath was dissected and longitudinally cut along the catheter to evaluate its extension in relation to the catheter. Relevant portions of the fibrous sheath were sent for pathology examination. The fibrous sheath covered the catheter in its entire length and circumference. It started at the entry site and continued without any interruption along the entire length of the catheter, including the tip. Its average thickness is 1 mm and has an inner cellular/inflammatory layer comprising lymphocytes, plasma cells, neutrophils, macrophages, multinucleated giant cells, and spindled cells and an outer layer comprising a mixture of collagen and fibroblasts. Our model showed that the fibrous sheath forms around all catheters and covers them in their entire length and circumference without any gaps.

Surgical technique of placement of an external jugular tunneled hemodialysis catheter in a large pig model.

Currently, there is insufficient knowledge about the surgical anatomy and surgical techniques in large animals that can be used to test medical devices designed for human use. We encountered this problem in our study requiring the placement of jugular vein, tunneled, cuffed hemodialysis catheter in 70 kg pigs. Despite the operator's extensive expertise in placing tunneled hemodialysis catheters in humans, the important differences in anatomy made the procedure and choosing the appropriate catheter length challenging. The following article describes the anatomy and our technique for the placement of tunneled hemodialysis catheter in the pig model. We consider our surgical technique to be sound because in all animals the catheters were placed in the desired location, the procedures were well tolerated by the animals, and there were no immediate or late complications. We present our experience to help other researchers who might encounter the same problem.