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

Characteristic CT angiography findings and clinical value of catheter-related central venous thrombosis in hemodialysis patients with end-stage renal disease

BACKGROUND

Central catheter-related thrombosis (CRT) is the most common catheter-related complication in patients with end-stage renal disease (ESRD) but is often underappreciated and misdiagnosed by radiologist.

PURPOSE

To find the computed tomography angiography (CTA) characteristics of central CRT, then raise the diagnosis of this disorder.

MATERIAL AND METHODS

A total of 301 eligible patients with ESRD who experienced both chest multi-phase multidetector CTA (MDCTA) and digital subtraction angiography were enrolled in the final analysis. The location, shape, and related signs of the central CRT in MDCTA images were evaluated. Independent-samples T test, chi-square test, and binary logistic regression were analyzed using SPSS software.

RESULTS

In total, 166 patients were found to have CRT using MDCTA, and this was verified by DSA. Central CRT was usually irregular in the superior vena cava segment, and the angle of the contact area between central CRT and catheter was <180° (all P < 0.05). Age, collateral circulation, and venous stenosis were shown to have significant differences when compared to patients without CRT (all P < 0.05), but there were no significant differences about the sex or catheter insertion site. In addition, age and collateral circulation were the factors found to be significantly associated with thrombosis (P < 0.05). In particular, the thrombosis was 2.213 times more likely to be found in those patients with collateral circulation (odds ratio = 2.213, 95% confidence interval = 1.236-3.961).

CONCLUSION

Chest multi-phase MDCTA can effectively reduce the missed diagnosis and misdiagnosis of central CRT. It is worth paying more attention to the central CRT especially when the collateral circulation is observed.

Assessment of the Tip Position of Central Venous Catheters Inserted Using Peres' Height Formula

OBJECTIVES

The tip of a central venous catheter (CVC) should be positioned in the proximity of the cavo-atrial junction (CAJ) where the lower third of the superior vena cava (SVC) and the upper right atrium (RA) are located to prevent life-threatening complications. This study aimed to determine the accuracy of Peres' height formula in predicting the correct insertion depth of CVC.  Methods: A total of 332 patients were enrolled in this prospective observational study. All CVCs were inserted using Peres' formula. The 'correct' tip position of CVC was the placement of the CVC tip 1 cm above and 1 cm below the carina in CXR. Rates of correct placements for each side and site of catheter insertions, gender, and body mass index (BMI) differences were evaluated.

RESULTS

The correct placement rate of all catheters was 74.4%. There were statistically significant correlations between the correct placement of right-sided jugular and subclavian catheters (p<0.001) and left-sided jugular and subclavian catheters (p=0.014). There was a statistically significant difference in male patients (p=0.047). Higher BMI resulted in a lower rate of correct placement with no statistically significant difference (p=0.457).

CONCLUSIONS

Peres' formula can be easily used to determine the correct position of CVC tips with a success rate in the Turkish population. However, practitioners should be aware of the low accuracy rate of Peres' formula in female patients (68.5%) and patients with BMI over 35 kg/m² (62.5%).

Influence of Hemodialysis Catheter Insertion on Hemodynamics in the Central Veins

Central venous catheter (CVC) related thrombosis is a major cause of CVC dysfunction in patients under hemodialysis. The aim of our study was to investigate the impact of CVC insertion on hemodynamics in the central veins and to examine the changes in hemodynamic environments that may be related to thrombus formation due to the implantation of CVC. Patient-specific models of the central veins with and without CVC were reconstructed based on computed tomography images. Flow patterns in the veins were numerically simulated to obtain hemodynamic parameters such as time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), relative residence time (RRT), and normalized transverse wall shear stress (transWSS) under pulsatile flow. The non-Newtonian effects of blood flow were also analyzed using the Casson model. The insertion of CVC caused significant changes in the hemodynamic environment in the central veins. A greater disturbance and increase of velocity were observed in the central veins after the insertion of CVC. As a result, TAWSS and transWSS were markedly increased, but most parts of OSI and RRT decreased. Newtonian assumption of blood flow would overestimate the increase in TAWSS after CVC insertion. High wall shear stress (WSS) and flow disturbance, especially the multidirectionality of the flow, induced by the CVC may be a key factor in initiating thrombosis after CVC insertion. Accordingly, approaches to decrease the flow disturbance during CVC insertion may help restrain the occurrence of thrombosis. More case studies with pre-operative and postoperative modeling and clinical follow-up need to be performed to verify these findings. Non-Newtonian blood flow assumption is recommended in computational fluid dynamics (CFD) simulations of veins with CVCs.