Microbiota of long-term indwelling hemodialysis catheters during renal transplantation perioperative period: a cross-sectional metagenomic microbial community analysis

Background: Catheter-related infection (CRI) is a major complication in patients undergoing hemodialysis. The lack of high-throughput research on catheter-related microbiota makes it difficult to predict the occurrence of CRI. Thus, this study aimed to delineate the microbial structure and diversity landscape of hemodialysis catheter tips among patients during the perioperative period of kidney transplantation (KTx) and provide insights into predicting the occurrence of CRI.Methods: Forty patients at the Department of Transplantation undergoing hemodialysis catheter removal were prospectively included. Samples, including catheter tip, catheter outlet skin swab, catheter blood, peripheral blood, oropharynx swab, and midstream urine, from the separate pre- and post-KTx groups were collected and analyzed using metagenomic next-generation sequencing (mNGS). All the catheter tips and blood samples were cultured conventionally.Results: The positive detection rates for bacteria using mNGS and traditional culture were 97.09% (200/206) and 2.65% (3/113), respectively. Low antibiotic-sensitivity biofilms with colonized bacteria were detected at the catheter tip. In asymptomatic patients, no statistically significant difference was observed in the catheter tip microbial composition and diversity between the pre- and post-KTx group. The catheter tip microbial composition and diversity were associated with fasting blood glucose levels. Microorganisms at the catheter tip most likely originated from catheter outlet skin and peripheral blood.Conclusions: The long-term colonization microbiota at the catheter tip is in a relatively stable state and is not readily influenced by KTx. It does not act as the source of infection in all CRIs, but could reflect hematogenous infection to some extent.

[Study on Influencing Factors of the Tip Softness of Epidural Anesthesia Catheter]

This article aims to study the factors affecting the flexibility of the tip of an epidural anesthesia catheter. The flexibility of the tip of the epidural anesthesia catheter was tested with a softness tester from four aspects:raw materials, tip structure, tip processing technology, and the outer diameter of the catheter. Highly flexible and malleable polymer material with a smooth tip, the tip softening process and the proper outer diameter can effectively improve the tip flexibility of the epidural anesthesia catheter.

Durability of tunneled catheters in children is associated with catheter tip depth: A single-center report

The aim of this study was to examine the impact of different catheter tip positions on catheter duration and dysfunction of tunneled catheters in children. Catheters were evaluated for place of insertion, time of insertion, catheter tip depth and position, duration of use, and reason for removal. The mean duration of implanted catheters with tips placed in cavo-atrial junction/right atrium was significantly longer with significantly lower percentage of complications than tips placed in superior vena cava. Only catheter tips placed in cavo-atrial junction/right atrium was a predictor of catheter functionality and survival. Shorter catheter survival in children with tunneled catheters is a consequence of a catheter tip depth proximal of CAJ and RA. Our results showed that the main factor responsible for better catheter functionality was not laterality but the depth of the catheter tip, which reduces need for future catheter insertions with increased catheter durability.

Catheter-related infections: does the spectrum of microbial causes change over time? A nationwide surveillance study

OBJECTIVES

To estimate the incidence and epidemiology of catheter-related bloodstream infections (CRBSIs) on a national scale by using prospective epidemiological data from the Swiss Antibiotic Resistance Surveillance System (ANRESIS).

DESIGN

Observational study.

SETTING

National surveillance from 2008 to 2015 of acute hospitals in Switzerland.

PARTICIPANTS

We included acute Swiss hospitals that sent blood cultures and catheter tip culture results on a regular basis during the entire study period to the ANRESIS database.

OUTCOME MEASURE

A catheter-related bloodstream infection (termed 'modified CRBSI', mCRBSI) was defined as isolating the same microorganism with identical antibiogram from ≥1 blood cultures (performed ±7 days around the catheter removal) as the one recovered from the catheter tip. Incidence rates of mCRBSI were calculated per 1000 admissions.

RESULTS

From 2008 to 2015, the mCRBSI incidence rate decreased from 0.83 to 0.58 episodes/1000 admissions (-6% per year, p<0.001). Coagulase-negative staphylococci, Staphylococcus aureus and fungi all exhibited decreasing trends, while rates of enterococci and Gram-negative bacteria remained stable.

CONCLUSIONS

The overall incidence of mCRBSI in Switzerland is decreasing; however, the incidence of mCRBSI due to Enterococci and Gram-negative micro-organisms did not change over time. These pathogens may grow in importance in catheter-related infections, which would have clinical implications for the choice of empirical treatment.

Electrocardiogram-guided Technique: An Alternative Method for Confirming Central Venous Catheter Tip Placement

Background

The current standard followed for assessing central venous catheter (CVC) tip placement location is through radiological confirmation using chest X-ray (CXR). Placement of CVCs under electrocardiogram (ECG) guidance may save cost and time compared to CXR.

Objective

The objective of this study is to compare the accurate placement of the CVC tip using anatomical landmark technique with ECG-guided technique. Another objective is to compare CVC placement time and postprocedural complications between the two techniques.

Methods and Materials

A total of 144 adult individuals, who were critically ill and required CVC placement in the Emergency Department, were included for the study. Study duration was 6 months. Anatomical landmark and ECG-guided groups were assigned 72 participants each. Analyses were performed using t and Chi square-tests.

Results

It was observed that 13 (18%) in the landmark technique were malpositioned as compared to none in the ECG-guided technique (P = 0.000). The landmark group had 22 (30.6%) participants with arrhythmias during the procedure, compared to none in the ECG-guided group (P = 0.000). The landmark group revealed that 30 (41.7%) of the CVC were overinserted and required immediate repositioning, compared to none in the ECG-guided group (P = 0.000).

Conclusion

ECG-guided technique was found to be more accurate for CVC tip placement than the anatomical landmark technique. Furthermore, the ECG-guided technique was more time-effective and had less complications than the anatomical landmark technique. Hence, ECG-guided CVC placement is relatively accurate, efficient, and safe and can be considered as an alternative method to conventional radiography for confirmation of CVC tip placement.

Direct cooling of the catheter tip increases safety for CMR-guided electrophysiological procedures

BACKGROUND

One of the safety concerns when performing electrophysiological (EP) procedures under magnetic resonance (MR) guidance is the risk of passive tissue heating due to the EP catheter being exposed to the radiofrequency (RF) field of the RF transmitting body coil. Ablation procedures that use catheters with irrigated tips are well established therapeutic options for the treatment of cardiac arrhythmias and when used in a modified mode might offer an additional system for suppressing passive catheter heating.

METHODS

A two-step approach was chosen. Firstly, tests on passive catheter heating were performed in a 1.5 T Avanto system (Siemens Healthcare Sector, Erlangen, Germany) using a ASTM Phantom in order to determine a possible maximum temperature rise. Secondly, a phantom was designed for simulation of the interface between blood and the vascular wall. The MR-RF induced temperature rise was simulated by catheter tip heating via a standard ablation generator. Power levels from 1 to 6 W were selected. Ablation duration was 120 s with no tip irrigation during the first 60 s and irrigation at rates from 2 ml/min to 35 ml/min for the remaining 60 s (Biotronik Qiona Pump, Berlin, Germany). The temperature was measured with fluoroscopic sensors (Luxtron, Santa Barbara, CA, USA) at a distance of 0 mm, 2 mm, 4 mm, and 6 mm from the catheter tip.

RESULTS

A maximum temperature rise of 22.4°C at the catheter tip was documented in the MR scanner. This temperature rise is equivalent to the heating effect of an ablator's power output of 6 W at a contact force of the weight of 90 g (0.883 N). The catheter tip irrigation was able to limit the temperature rise to less than 2°C for the majority of examined power levels, and for all examined power levels the residual temperature rise was less than 8°C.

CONCLUSION

Up to a maximum of 22.4°C, the temperature rise at the tissue surface can be entirely suppressed by using the catheter's own irrigation system. The irrigated tip system can be used to increase MR safety of EP catheters by suppressing the effects of unwanted passive catheter heating due to RF exposure from the MR scanner.