Cerebral microbleeds in acute ischemic stroke after intravenous thrombolysis and their impact on short term outcome of stroke.

OBJECTIVES: Strong evidence suggests the occurrence of cerebral microbleeds (CMBs) in 5-13% of stroke patients within the first week after stroke onset. The aim of this work was to study risk factors associated with occurrence of CMBs in patients with stroke who received intravenous thrombolysis, and to clarify their impact on the clinical outcome. METHODS: This prospective observational study was conducted on 61 acute ischemic stroke patients eligible for treatment with recombinant tissue plasminogen activator (rt-PA). Assessment of stroke-related neurologic deficit was done using National Institute of Health Stroke Scale (NIHSS). Assessment of stroke related disability after 3 months from stroke onset was done using Modified Rankin Scale (mRS). CMBs were detected by T2*-weighed gradient-recalled echo (T2*-GRE) and susceptibility-weighted imaging (SWI) magnetic resonance imaging (MRI) sequences. RESULTS: There was a statistically significant impact of age, mean arterial pressure (MAP) at stroke onset, history of hypertension (HTN), and white matter changes assessed by Fazekas scale on the occurrence of CMBs in the included stroke patients (P-value= 0.002, <0.001, <0.001, 0.008 respectively). There was no statistically significant difference between patients with favorable and those with unfavorable outcome regarding the total number of CMBs (P-value =0.542). There was also no statistically significant difference between patients who developed complications from rt-PA and those who didn't develop regarding the total number of CMBs (P-value =0.186). CONCLUSION: Cerebral microbleeds are more likely to occur in older stroke patients and in those who had high MAP at stroke onset, history of HTN, and white matter changes.

Global calibration for non-targeted fraud detection in quinoa flour using portable hyperspectral imaging and chemometrics.

Quinoa is one of the highest nutritious grains, and global consumption of quinoa flour has increased as people pay more attention to health. Due to its high value, quinoa flour is susceptible to adulteration. Cross-contamination between quinoa flour and other flour can be easily neglected due to their highly similar appearance. Therefore, detecting adulteration in quinoa flour is important to consumers, industries, and regulatory agencies. In this study, portable hyperspectral imaging in the visible near-infrared (VNIR) spectral range (400-1000 nm) was applied as a rapid tool to detect adulteration in quinoa flour. Quinoa flour was adulterated with wheat, rice, soybean, and corn in the range of 0-98% with 2% increments. Partial least squares regression (PLSR) models were developed, and the best model for detecting the % authentic flour (quinoa) was obtained by the raw spectral data with R2p of 0.99, RMSEP of 3.08%, RPD of 8.77, and RER of 25.32. The model was improved, by selecting only 13 wavelengths using bootstrapping soft shrinkage (BOSS), to R2p of 0.99, RMSEP of 2.93%, RPD of 9.18, and RER of 26.60. A visualization map was also generated to predict the level of quinoa in the adulterated samples. The results of this study demonstrate the ability of VNIR hyperspectral imaging for adulteration detection in quinoa flour as an alternative to the complicated traditional method.

Survival and Toxicities after 90Y Transarterial Radioembolization of Metastatic Colorectal Cancer in the RESIN Registry.

Background Patients with unresectable, chemorefractory hepatic metastases from colorectal cancer have considerable mortality. The role of transarterial radioembolization (TARE) with yttrium 90 (90Y) microspheres is not defined because most reports are from a single center with limited patient numbers. Purpose To report outcomes in participants with colorectal cancer metastases treated with resin 90Y microspheres from a prospective multicenter observational registry. Materials and Methods This study treated enrolled adult participants with TARE using resin microspheres for liver-dominant metastatic colorectal cancer at 42 centers, with enrollment from July 2015 through August 2020. TARE was used as the first-, second-, or third-line therapy or beyond. Overall survival (OS), progression-free survival (PFS), and toxicity outcomes were assessed by line of therapy by using Kaplan-Meier analysis for OS and PFS and Common Terminology Criteria for Adverse Events, version 5, for toxicities. Results A total of 498 participants (median age, 60 years [IQR, 52-69 years]; 298 men [60%]) were treated. TARE was used in first-line therapy in 74 of 442 participants (17%), second-line therapy in 180 participants (41%), and third-line therapy or beyond in 188 participants (43%). The median OS of the entire cohort was 15.0 months (95% CI: 13.3, 16.9). The median OS by line of therapy was 13.9 months for first-line therapy, 17.4 months for second-line therapy, and 12.5 months for third-line therapy (χ2 = 9.7; P = .002). Whole-group PFS was 7.4 months (95% CI: 6.4, 9.5). The median PFS by line of therapy was 7.9 months for first-line therapy, 10.0 months for second-line therapy, and 5.9 months for third-line therapy (χ2 = 8.3; P = .004). TARE-attributable grade 3 or 4 hepatic toxicities were 8.4% for bilirubin (29 of 347 participants) and 3.7% for albumin (13 of 347). Grade 3 and higher toxicities were greater with third-line therapy for bilirubin (P = .01) and albumin (P = .008). Conclusion Median overall survival (OS) after transarterial radioembolization (TARE) with yttrium 90 microspheres for liver-dominant metastatic colorectal cancer was 15.0 months. The longest OS was achieved when TARE was part of second-line therapy. Grade 3 or greater hepatic function toxicity rates were less than 10%. Clinical trial registration no. NCT02685631 Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Liddell in this issue.

Outcomes of transjugular intrahepatic portosystemic shunt using 12 mm diameter polytetrafluoroethylene covered stents in cirrhotic patients with portal hypertension.

PURPOSE We aimed to evaluate the safety and efficacy of 12 mm diameter polytetrafluoroethylene (PTFE)- covered stents for the creation of transjugular intrahepatic portosystemic shunt (TIPS) in cir- rhotic patients with portal hypertension complicated by variceal bleeding and volume-overload. METHODS This retrospective study included 360 patients who had TIPS created between January 2004 and December 2017 using 12 mm diameter PTFE-covered stents. Demographic data, model for end- stage liver disease (MELD) score, etiology of cirrhosis, and Charlson comorbidity index were recorded. Symptoms of hepatic encephalopathy (HE), variceal re-bleeding, improvement in vol- ume-overload, TIPS revisions and the need for intervention, and overall survival were assessed. RESULTS The mean age of the patients was 56.8 ± 9.9 years, and the technical success rate was 99.4%. The rates of improvement of volume-overload post-TIPS were 59.5%, 69.8%, and 81.7% at 3, 6, and 12 months, respectively. About 93.3% of patients were free from paracentesis or thoracentesis at 12 months. The rates of re-bleeding post-TIPS were 4%, 12%, and 12.9% at 3, 6, and 12 months, respectively. The rate of TIPS revision at 12 months was 6.5%. Percentage of patients with any symptoms of HE were 34.4%, 42.9%, and 49.5% at 3, 6, and 12 months, respectively. All HE were appropriately medically managed and no patients required a TIPS reduction. CONCLUSION TIPS placement using 12 mm PTFE-covered stents is efficacious in cirrhotic patients with portal hypertension complicated by variceal bleeding or refractory volume-overload, with an accept- able safety profile.

Feasibility of Creation of an Endovascular Arteriovenous Fistula in Patients Undergoing Preoperative Vascular Mapping.

Background: The first endovascular arteriovenous fistula (endoAVF) device (WavelinQ), a novel percutaneous technique of AVF creation, was approved by the Food and Drug Administration in 2018 and has been placed in a small number of United States patients on hemodialysis. It is unknown how often patients with advanced CKD have vascular anatomy suitable for WavelinQ creation. The goal of this study was to determine the proportion of patients with vascular anatomy suitable for WavelinQ creation and to assess patient characteristics associated with such suitability. Methods: All patients referred for vascular access placement at a large academic medical center underwent standardized preoperative sonographic vascular mapping to assess suitability for an AVF. During a 2-year period (March 2019 to March 2021), we assessed the suitability of the vessels for creation of WavelinQ. We then compared the demographic characteristics, comorbidities, and vascular mapping measurements between patients who were or were not suitable for WavelinQ. Results: During the study period, 437 patients underwent vessel mapping. Of these, 51% of patients were eligible for a surgical AVF, and 32% were eligible for a WavelinQ AVF; 63% of those suitable for a surgical AVF were also suitable for a WavelinQ AVF. Patients with a vascular anatomy suitable for WavelinQ were younger (age 55±15 versus 60±14 years, P=0.01) but similar in sex, race, diabetes, hypertension, coronary artery disease, and peripheral artery disease. Conclusions: Among patients with CKD with vascular anatomy suitable for a surgical AVF, 63% are also suitable for a WavelinQ endoAVF. Older patients are less frequently suitable for WavelinQ.

Complications of Percutaneous Peritoneal Dialysis Catheter.

A functional peritoneal dialysis (PD) catheter is the cornerstone for the success of renal replacement therapy. This success is largely dependent on adhering to best practices during catheter insertion, which starts with a comprehensive preoperative evaluation that helps in determining the catheter configuration type and both entry and exit sites. Additionally, following the best practice guidelines during PD catheter insertion minimizes undesirable complications and provides a durable functional access for dialysis. However, adverse complications are still encountered despite abiding with these clinical guidelines. These complications are categorized into mechanical and infectious groups. The description and management of these adverse events are discussed in detail in this article with particular attention to the technical pitfalls that can occur during catheter insertion. Avoiding these pitfalls can minimize PD catheter complications and potentially improve clinical outcomes.

Peritoneal Dialysis Catheter Placement: Percutaneous and Peritoneoscopic Techniques.

Chronic peritoneal dialysis (PD) is an underutilized renal replacement therapy in treating end-stage renal disease that has several advantages over hemodialysis. The success of continuous ambulatory PD is largely dependent on a functional long-term access to the peritoneal cavity. Several methods have been developed to place the PD catheter using both surgical and percutaneous techniques. The purpose of this article is to describe the percutaneous techniques using fluoroscopy guidance and peritoneoscope method. While fluoroscopic method uses fluoroscopy guidance and a guidewire to place the PD catheter, the peritoneoscopic technique utilizes a needlescope to directly visualize the peritoneal space to avoid adhesions and omentum during catheter placement. These percutaneous approaches are minimally invasive procedures that can be performed on an outpatient basis without the need for general anesthesia.

Why Peritoneal Dialysis is Underutilized in the United States: A Review of Inequities.

Given a choice, most patients with end-stage renal disease prefer home dialysis over in-center hemodialysis (HD). Peritoneal dialysis (PD) is a home dialysis method and offers benefits such as absence of central venous access and therefore preservation of veins, low cost, and decreased time per dialysis session, as well as convenience. Survival rate for patients on PD has increased to levels comparable to in-center HD. Despite endorsement by leaders in the medical field, professional societies, and those in government, PD has reached only 11% adoption among incident patients according to the 2019 United States Renal Data System Annual Data Report. This figure is dwarfed in comparison to rates as high as 79% in other countries. In addition, research has shown that inequities exist in PD access, which are most pronounced in rural, minority, and low-income regions as demonstrated by trends in regional PD supplies. To complicate things further, technique failure has been implicated as a major determinant of poor PD retention rates. The low initiation and retention rates of PD in the United States points to barriers within the healthcare system, many of which are in the early phases of being addressed.

Devices and Techniques for Percutaneous Creation of Dialysis Arteriovenous Fistulas.

Dialysis treatment for chronic kidney disease was first developed by Dr. Willem Kolff in 1943, and its availability began to grow in 1962 after which it has become a mainstay treatment for patients with chronic kidney disease. It is estimated that, in 2021, 15% of adults in the United States (∼37 million people) have chronic kidney disease, of which 661,000 individuals have renal failure, and 468,000 individuals require dialysis. There have been several advancements in dialysis treatment since its advent, most notably the creation of arteriovenous fistulas (AVFs) for venous access in 1966. In recent years, the U.S. Food and Drug Administration approved two new devices for AVF creation using a percutaneous approach. These are the WavelinQ (Becton Dickinson, New Jersey) and the Ellipsys (Avenu Medical, California) endovascular AVF (endoAVF) devices that use radiofrequency and thermal technologies, respectively, to create the AVF. Since the introduction of these technologies, several studies have shown that they are safe and effective, with favorable durability and low rate of serious adverse events. In this article, we will discuss these two devices and the techniques used for percutaneous creation of dialysis AVF as an alternative to traditional open surgical techniques.

Endovascular embolization for managing a massive shoulder arteriovenous malformation.

Arteriovenous malformations (AVMs) are congenital high flow pathologic linkages between arteries and veins of different sizes that may occur in any part of the body. The clinical presentation is largely dependent on the size and location of AVMs and can range from an asymptomatic birthmark to congestive heart failure in extreme cases. In this report, we describe a 20-year-old male who presented with a large AVM of the right shoulder that resulted in significant cosmetic and physical impairment and treated with several sessions of endovascular embolization with good clinical outcomes. This case highlights the complexity of diagnosing and managing these AVMs. Most of these anomalies require a multi-disciplinary approach that integrates both trans-catheter and surgical interventions with trans-arterial lesion embolization being the cornerstone of the treatment.

Endovascular Management of Pelvic Trauma.

Major pelvic fractures result from high-energy trauma including traffic accidents and falls, which usually leads to multiple injuries complicating the patient's management. Management of these patients requires a coordinated multidisciplinary approach. Transcatheter embolization is a minimally invasive and effective technique to control massive hemorrhage and can be performed using a variety of embolic agents. It has become an accepted first-line management option for retroperitoneal bleeds in many centers. In this article, the indications for endovascular management of hemorrhage from pelvic trauma, the various embolization techniques, and potential complications will be discussed.

Comparative Study on the Outcomes of Elective-Start versus Urgent-Start Peritoneal Dialysis Catheter Placement.

The aim of this study is to compare the outcomes of the elective-start versus urgent-start use of peritoneal dialysis (PD) catheters using percutaneous radiologic or laparoscopic techniques. Patients having their first peritoneal dialysis catheter placed and used between January 2005 and January 2018 were identified, and their medical records were retrospectively reviewed. Two groups were identified: elective-start (n = 211) and urgent-start (n = 29). Patient's demographics were similar between the two groups with the exception of age, which was higher in the elective-start group. The catheter complication rates and catheter removal rates at 3 and 12 months, mean days-to-first complication, mean days-to-catheter removal, and overall patient survival at 12 months were analyzed. Catheter complication rates at 3 and 12 months were similar between the two groups (27.8% and 48.9%, respectively, in the elective-start group versus 35.9% and 54.2%, respectively, in the urgent-start group, p=0.415). The catheter removal rates at 3 and 12 months were also similar between the two groups (p=0.088). Catheter leak was higher in the urgent-start group (13.8% versus 3.3%, respectively, p=0.011). There was no difference between the elective-start and the urgent-start groups in the mean days-to-first complication (95 vs 69, p=0.086), mean days-to-catheter removal (145 vs 127, p=0.757), and overall patient survival at 12 months (100% vs 97%, p=0.41). In conclusion, apart from catheter leak, there were similar rates of catheter complication and removal for PD catheter used for the elective-start compared to the urgent-start PD. Furthermore, the technique of placement did not affect the outcomes.

Risk Factors for Surgical Site Infection after Operative Fixation of Acetabular Fractures: Is Psoas Density a Useful Metric?

BACKGROUND: Surgical site infection (SSI) occurs in 5% to 7% of patients undergoing operative fixation of acetabular fractures, with reported risk factors including longer operative duration, increased blood loss, pelvic artery embolization, and concurrent abdominal organ injury, among others. Psoas muscle density is a measure of muscle quality and, as a metric for sarcopenia and/or nutrition status, has been associated with poor outcomes such as mortality across multiple surgical specialties. To date, psoas muscle density has not been explored for its associations with SSI in acetabular fracture patients.Questions/purposes (1) Is decreased psoas muscle density, as measured by Hounsfield units, associated with an increased SSI risk after acetabular fracture fixation? (2) What patient, operative, and hospital variables are associated with an increased SSI risk after acetabular fracture fixation? METHODS: Between 2012 to 2017, surgeons performed 684 acetabular ORIF procedures at one level I trauma center. Of those, 8% (56 of 684) did not meet inclusion criteria, leaving 92% (n = 628) for analysis in this study. The median (range) follow-up duration was 12 months (0.5-77). Patient demographics, comorbidities, operative and in-hospital variables, and psoas muscle density measured using preoperative pelvic CT images-acquired for all operative acetabular fracture patients-were analyzed. SSI was defined by positive culture results obtained during irrigation and débridement. Overall, 7% (42 of 628) of patients had an SSI. A multivariable regression analysis was performed to identify independent risk factors. Sensitivity analysis was performed with minimum follow-up set at 3 months and 6 months. RESULTS: There was no difference in the mean psoas muscle density between patients with SSI (50.9 ± 10.2 Hounsfield units [HUs]) and those who did not have an SSI within 1 year of open reduction and internal fixation (51.4 ± 8.1 HUs) (mean difference: 0.5 [95% confidence interval -2.34 to 3.32]; p = 0.69). Four variables were independently associated with an increased risk of SSI: increased operative time (1.04 [95% CI 1.00 to 1.07]; p = 0.03), estimated blood loss (1.08 [95% CI 1.02 to 1.14]; p = 0.01), female sex (2.34 [95% CI 1.19 to 4.60]; p = 0.01), and intravenous drug use (3.95 [95% CI 1.51 to 10.33]; p = 0.01). Sensitivity analysis showed no change in results using either 3-month or 6-month minimum follow-up. CONCLUSIONS: Risk factors for SSI after acetabular fixation include female sex, intravenous drug use, prolonged operative times, and increased intraoperative blood loss. Although the density of the psoas muscle may be a surrogate for nutritional markers, it was not associated with SSI in our patients with acetabular fractures. Thus, it is not useful for risk assessment of SSI in the general population with acetabular fracture; however, future studies with larger sample sizes of patients older than 60 years may re-investigate this marker for SSI risk. Contrary to the results of previous studies, pelvic artery embolization, intraoperative blood transfusion, and intensive care unit stay did not increase the risk of SSI; however, we may have been underpowered to detect differences in these secondary endpoints. Future large, multisite studies may be needed to address these conflicting results more definitively. LEVEL OF EVIDENCE: Level III, therapeutic study.

Percutaneous Cryoablation of Stage T1b Renal Cell Carcinoma: Safety, Technical Results, and Clinical Outcomes.

PURPOSE: The use of percutaneous cryoablation for T1b (4.1-7.0 cm) renal cell carcinoma, has not yet been widely adopted. The purpose of this study was to describe our experience in the cryoablation of stage T1b tumors with an emphasis on safety, technical results, and clinical outcomes. MATERIALS AND METHODS: A retrospective review of hospital records identified 37 patients who underwent cryoablation for T1b lesions from 2008 to 2018. Patient demographics, comorbidities, tumor characteristics, technical parameters, and outcomes were recorded and analyzed. Recurrence-free, overall, and cancer-specific survival rates were estimated using the Kaplan-Meier method. RESULTS: Thirty-seven patients (22 males, 15 females; mean age 66.5 ± 11.3) with 37 T1b tumors (mean diameter 47.3 ± 6.3 mm) were included. A median of 3 probes were used (range: 1-7). Angio-embolization was used in 3/37 (8.1%) and 2/37 patients (5.4%) required hydrodissection. The mean number of total cryoablation procedures for each patient was 1.5 (median 1; range: 1-4). Technical success was achieved in 88.2% of patients. Recurrence-free survival was 96.5%, 86.1%, and 62.6% at 1, 2, and 3 years respectively. Cancer-specific survival was 100% at 1, 2, and 3 years respectively. Overall survival was 96.7%, 91.8%, and 77.6% at 1, 2, and 3 years respectively. Complications classified as CIRSE grade 2 or higher occurred in 6/37 (16.2%) patients. CONCLUSION: T1b cryoablation is associated with high rates of technical success, excellent cancer-specific survival, and an acceptable safety profile. LEVEL OF EVIDENCE: Level 4, Case Series.

Erratum: Outcomes of fluoroscopic and ultrasound-guided placement versus laparoscopic placement of peritoneal dialysis catheters.

[This corrects the article DOI: 10.1093/ckj/sfx132.].

Psoas Muscle Density in Combination with Model for End-Stage Liver Disease Score Can Improve Survival Predictability in Transjugular Intrahepatic Portosystemic Shunts.

PURPOSE: To examine the role of psoas muscle density (PD) measurement before transjugular intrahepatic portosystemic shunt (TIPS) creation in predicting survival when combined with Model for End-stage Liver Disease (MELD) score. MATERIALS AND METHODS: The medical records of 241 patients with cirrhosis who underwent TIPS creation between June 2005 and June 2015 were retrospectively reviewed. The patients were divided into 2 groups: those with variceal bleeding (VB; n = 113) and those with volume overload (VO; n = 128). The study included 149 men (62%), and mean patient age was 56 years ± 9.6 (range 24-83). Mean MELD score before TIPS creation was 11.8 ± 5.7. A threshold sensitivity of pre-TIPS PD for the assessment of mortality was calculated and then correlated with survival after TIPS creation. Receiver operating characteristic curves comparing 12-month mortality were used to assess the improvement in survival predictability after TIPS creation when the PD threshold was combined with MELD score vs MELD score alone. RESULTS: Mean post-TIPS follow-up was 29.9 month ± 34.1 (range 1-3700 days). There was no significant difference in 3- or 12-month mortality rates between the VB and VO groups (32.7% vs 25.8% [P = .23] and 46% vs 46.1% [P = .99], respectively). The MELD score threshold for prediction of survival was 15 (P < .0001). There was no difference in the mean PD between VB and VO groups (34.2 HU ± 8.8 and 33.1 HU ± 10.3, respectively; P = .359). The increase in MELD score after TIPS creation was significant in both groups (VB, P = .0013; VO, P < .0001). The threshold of pre-TIPS PD for discrimination of survival was 29.4 HU (P < .0001), and PD measurements greater than this threshold were associated with a lower risk of mortality (hazard ratio, 0.27; 95% confidence interval, 0.13-0.57; P = .0006). Compared with the use of MELD score alone, the addition of PD measurement significantly increased the area under the curve from 0.61 to 0.68 (P = .0006). CONCLUSIONS: Measurement of PD improved overall survival predictability in patients with cirrhosis undergoing TIPS creation when used in conjunction with MELD score. The best survival outcome was observed in patients with MELD score < 15 in combination with PD > 29.4 HU.

Aortic Paravalvular Leak Repair: Can TAVR Be the Answer?

A 71-year-old male with endocarditis mediated severe paravalvular leak and nonischemic cardiomyopathy underwent percutaneous repair attempts with a closure device followed by valve-in-valve transcatheter aortic replacement procedure. The case was complicated by cardiac arrest requiring hemodynamic support with Impella placement and secondary iatrogenic central aortic insufficiency requiring further intervention. (Level of Difficulty: Beginner.).

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

PURPOSE: To assess the ability of various clinical factors to predict infection or dysfunction of tunneled hemodialysis catheters. METHODS: 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. RESULTS: 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. CONCLUSION: 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.