The Journal of Vascular Access

The purpose of this study is to analyse literature related to the position of centrally inserted central venous catheters and to review topics related to assessment of tip position of those catheters in children. Applications of specific techniques to PICCs (Periferally Inserted Central Catheters) and umbilical venous catheter will also be reviewed.

Analysis of 68 original manuscripts, 42 specifically related to the paediatric population, 26 related to the adult population. The papers analysed were published between 1949 and 2014; all articles were in English except one in Italian and one in German.

From the analysed literature, most of the guidelines recommend tip positioning at a level between the superior vena cava and the right atrium. Several methods have been described to evaluate tip position in the paediatric population, but none of those is considered completely reliable. The standard methods used to identify catheter tip position are radiography and fluoroscopy, but no specific landmark can be recommended in the paediatric population. The ultrasonographic approach has been investigated mainly for PICCs positioning in the neonatal population. The electrocardiographic method has been evaluated in the general paediatric population.

No specific recommendation can be given due to the low level of evidence. Ultrasound and ECG (electrocardiogram) techniques are a potential alternative to chest X-ray and further studies should be implemented to establish them. A wider application of these techniques may reduce neonatal and paediatric exposure to radiations and additionally reduce costs.

This article reviews the conventional vascular access types in the upper extremities for hemodialysis.

We performed a literature search for autogenous arteriovenous fistula in the upper extremities.

The upper extremities have four potential sites: radio-cephalic or radio-basilic transposition in the forearm, and brachio-cephalic or brachio-basilic transposition in the upper arm. A pre-operative Duplex ultrasound provides valuable information regarding arterial inflow and venous outflow. The surgical approach to fistula formation and final product depends on vein diameter and length as well as proximal vein patency. The discussion focuses on access outcomes and management of common complications.

The upper extremity arteriovenous fistula is the preferred access for hemodialysis. A number of arteriovenous fistulas can be created in the upper extremities. The Duplex ultrasound identifies suitable arteries and veins for successful arteriovenous hemodialysis fistula creation. Arteriovenous hemodialysis fistula has the best long-term patency outcomes and the lowest associated morbidity and mortality. Early detection and intervention can save the fistula when complications occur.

The venous limb of arteriovenous fistulae (AVF) adapts to the arterial environment by dilation and wall thickening; however, the temporal regulation of the expression of extracellular matrix (ECM) components in the venous limb of the maturing AVF has not been well characterized. We used a murine model of AVF maturation that recapitulates human AVF maturation to determine the temporal pattern of expression of these ECM components.

Aortocaval fistulae were created in C57BL/6J mice and the venous limb was analyzed on postoperative days 1, 3, 7, 21, and 42. A gene microarray analysis was performed on day 7; results were confirmed by qPCR, histology, and immunohistochemistry. Proteases, protease inhibitors, collagens, glycoproteins, and other non-collagenous proteins were characterized.

The maturing AVF has increased expression of many ECM components, including increased collagen and elastin. Matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase 1 (TIMP1) showed increased mRNA and protein expression during the first 7 days of maturation. Increased collagen and elastin expression was also significant at day 7. Expression of structural proteins was increased later during AVF maturation. Osteopontin (OPN) expression was increased at day 1 and sustained during AVF maturation.

During AVF maturation, there is significantly increased expression of ECM components, each of which shows distinct temporal patterns during AVF maturation. Increased expression of regulatory proteins such as MMP and TIMP precedes increased expression of structural proteins such as collagen and elastin, potentially mediating a controlled pattern of ECM degradation and vessel remodeling without structural failure.

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.

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.

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).

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.

The purpose of this study is to explore how vascular access care was reimbursed, promoted, and organised at the national level in European and neighbouring countries.

An electronic survey among national experts to collect country-level data.

Forty-seven experts (response rate, 76%) from 37 countries participated. Experts from 23 countries reported that 50% or less of patients received routine pre-operative imaging of vessels. Nephrologists placed catheters and created fistulas in 26 and 8 countries, respectively. Twenty-one countries had a fee per created access; the reported fee for catheter placement was never higher than for fistula creation. As the number of haemodialysis patients in a centre increased, more countries had a dedicated coordinator or multidisciplinary team responsible for vascular access maintenance at the centre-level; in 11 countries, responsibility was always with individual nephrologists, independent of a centre's size. In 23 countries, dialysis centres shared vascular access care resources, with facilitation from a service provider in 4. In most countries, national campaigns (n = 35) or educational programmes (n = 29) had addressed vascular access-related topics; 19 countries had some form of training for creating fistulas. Forty experts considered the current evidence base robust enough to justify a fistula-first policy, but only 13 believed that more than 80% of nephrologists in their country would attempt a fistula in a 75-year-old woman with comorbidities.

Suboptimal access to surgical resources, lack of dedicated training of clinicians, limited routine use of pre-operative diagnostic imaging and patient characteristics primarily emerged as potential barriers to adopting a fistula-first policy in Europe.

We retrospectively evaluated the surgical outcome of revising vascular access related aneurysms (VARAs) to salvage dialysis access.

Twenty-six consecutive hemodialysis patients (mean age 67.6 years, range: 32-89 years) who presented with true or false VARA and underwent surgery between January 2006 and February 2011 were enrolled in this study, and comprised 11 women and 15 men. Aneurysms were true in 21 patients and false in five; native arteriovenous fistulas (AVFs) were reported in 23, including one infected native pseudoaneurysm, and arteriovenous prosthetic grafts (AVGs) in three. The mean aneurysm diameter was 29.8 ±8.0 mm, ranging from 18 to 50 mm. Indications of surgical intervention were local pain, rapid enlargement of the aneurysm, and AVF failure due to stenosis. Surgical revision was performed by resection of VARA and concomitant creation of a new proximal arteriovenous anastomosis in 18 patients.

Two aneurysms were ruptured by blunt dissection; however, bleeding did not occur due to prior clamping of the inflow artery without hemodynamic compromise. VARA plication was performed in one case in which severe calcified VARA could not be incised. No significant complications were reported, except for delayed wound healing in three patients and minor peripheral neuropathy in five. The postoperative course was uneventful without hospital mortality in all patients with VARA.

Aggressive surgical management of VARAs is likely to become an acceptable procedure to salvage dialysis access and consistently maintain AVF or AVG function.

The Department of Health estimates that currently in the UK, 61.3% of the population are overweight or obese (BMI >25 kg/m²). Fistulae in the obese often fail to mature or prove inadequate to needle due to excessive depth (>6 mm). This study is a summary of our experience with brachio and radio-cephalic vein superficialisation in the obese.

From May 2008 to October 2012, 22 patients underwent superficialisation of the cephalic vein following radio-cephalic or brachio-cephalic Arterio-venous fistula (AVF) creation. Data were obtained from a prospective database (Cyberen^®) and retrospectively analysed.

The study included 23 AVFs in 22 patients (seven males, 15 females), of which 13 were brachio-cephalic and 10 radio-cephalic. The mean age of the patients was 56 years (median 60, range 19-78 years). The mean BMI was 36.7 kg/m² (median 32, 25-58 kg/m²). Six-week post procedure duplex ultrasonography recorded the mean fistula depth to be 7.7 mm (median 8 mm, 5-15 mm) and mean flow rates were 961 ml/min (median 800 ml/min, 320-1968 ml/min).

Of the 23, 21 fistulae matured successfully. There were no procedure-related complications. During follow-up, two patients underwent transplantation prior to fistula use and three patients died of unrelated causes. The remaining 16 fistulae remain in use and under access surveillance.

Superficialisation of brachio/radio-cephalic fistulae is an excellent option to optimise the cephalic vein for needling, assisting primary patency. Superficialisation of the cephalic vein helps maintain long-term functional access in overweight and obese patients.

Treatment of pediatric malignancies is becoming progressively more complex, implying the adoption of multimodal therapies. A reliable, long-lasting venous access represents one of the critical requirements for the success of those treatments. Recent technical innovations—such as minimally invasive procedures for placement, new devices and novel materials—have rapidly spread for clinical use in adult patients, but are still not consistently used in the pediatric population.

The Supportive Therapy Working Group of Italian Association of Hematology and Oncology (AIEOP) reviewed medical literature focusing on new aspects of central venous access devices (VADs) in pediatric patients affected by oncohematological diseases.

Appropriate recommendations for clinical use in these patients have been discussed and formulated.

The importance of the correct choice, management and use of VADs in pediatric oncohematological patients is a necessary prerequisite for an adequate standard of care, also considering the increased chances of cure and the longer life expectancy of those patients with modern therapies.

The Italian Group for Venous Access Devices (GAVeCeLT) has carried out a multicenter study investigating the safety and accuracy of intracavitary electrocardiography (IC-ECG) in pediatric patients.

We enrolled 309 patients (age 1 month-18 years) candidate to different central venous access devices

(VAD) - 56 peripherally inserted central catheters (PICC), 178 short term centrally inserted central catheters (CICC), 65 long term VADs, 10 VADs for dialysis - in five Italian Hospitals. Three age groups were considered: A (<4 years, n = 157), B (4-11 years, n = 119), and C (12-18 years, n = 31). IC-ECG was applicable in 307 cases. The increase of the P wave on IC-ECG was detected in all cases but two. The tip of the catheter was positioned at the cavo-atrial junction (CAJ) (i.e., at the maximal height of the P wave on IC-ECG) and the position was checked during the procedure by fluoroscopy or chest x-ray, considering the CAJ at 1-2 cm (group A), 1.5-3 cm (group B), or 2-4 cm (group C) below the carina.

There were no complications related to IC-ECG. The overall match between IC-ECG and x-ray was 95.8% (96.2% in group A, 95% in group B, and 96.8% in group C). In 95 cases, the IC-ECG was performed with a dedicated ECG monitor, specifically designed for IC-ECG (Nautilus, Romedex): in this group, the match between IC-ECG and x-ray was 98.8%.

We conclude that the IC-ECG method is safe and accurate in the pediatric patients. The applicability of the method is 99.4% and its feasibility is 99.4%. The accuracy is 95.8% and even higher (98.8%) when using a dedicated ECG monitor.

Both ultrasound-guided subclavian venipuncture (US-SV) and landmark-guided subclavian venipuncture (LM-SV) are important in critical care, because the clinical utility of ultrasound guidance is still debated. Education of residents and medical students should include both techniques. The aim of this study is to compare learning these two techniques in a simulation environment.

This study was approved by the research ethics review committee. Trainees included residents and medical students who were instructed using the “Videos in Clinical Medicine” for LM-SV, or a dedicated slide series for US-SV, using the long-axis in-plane with needle-guide technique. After the lecture, trainees attempted to perform venipuncture in a simulator. All participants performed both techniques. The procedure time from initial skin puncture to detecting back-flow of fluid from the simulated vein was measured. A procedure time over 3 min, arterial puncture, or pneumothorax was counted as a failure. The end-point for each trainee was three successive successful venipunctures without a failure. A trainee who reached the end-point was considered as having acquired adequate skill. Statistical analysis of the procedure time comparing the techniques was done using the Mann-Whitney U test.

Twenty trainees participated in this training. Adequate skill to perform US-SV was achieved within three tries, but up to nine attempts were needed for LM-SV. One arterial puncture occurred during LM-SV. No pneumothoraxes occurred during the simulation training.

US-SV was learned more quickly than LM-SV in a simulation model.

The use of ultrasound (US) guidance for central vascular access in children has been advocated as a safer approach compared to traditional landmark techniques. We therefore collected data on the current use of US for central vascular access in children and infants in the Nordic countries.

A cross-sectional survey using an online questionnaire was distributed to one anaesthesiologist at every hospital in the Nordic countries; a total of 177 anaesthesiologists were contacted from July till August 2012.

The use of US for placing central venous catheters (CVCs) seems widespread across the Nordic countries. Close to 80% of respondents were using it “almost always” or “frequently” across all paediatric age groups for internal jugular vein cannulation. US was least frequently used when catheterizing the subclavian vein. The two most common reasons given when not using US were lack of training followed by lack of equipment. We found no difference in the use of US between high-volume centres and low-volume centres. (High-volume centres placed paediatric CVCs at least weekly.)

US was commonly used for cannulation of the internal jugular vein but infrequently for the subclavian vein. A lack of training seems to be a barrier for further increasing the use of US. Establishing standardized training programmes based on current evidence should alleviate this.

The approach to repair inadvertent subclavian artery catheterization has evolved to increasingly less invasive modalities. Most recently, endovascular balloon tamponade has become the preferred initial approach. We report our experience and review the technique.

Eleven patients underwent primary treatment with balloon tamponade from 2001 to 2012. Using either femoral or brachial approach, an appropriately sized balloon was placed directly adjacent to the site of hemorrhage and inflated for 5-25 min on the basis of operator preference and repeated as needed. Primary technical success defined as hemostasis was achieved with balloon tamponade.

Technical success was achieved in nine of 11 patients. The mean follow-up time was 10.8 months. Two deaths were reported, both unrelated to catheter placement and removal. Of the successful cases, five achieved hemostasis with one inflation and four required two inflations. One patient developed a small thrombus at the thyrocervical trunk of no clinical significance. No other complications occurred. One of the nine patients had a double wall injury. The two patients with unsuccessful hemostasis underwent two & four inflations, respectively. Both patients had a double wall injury. One of the patients had a complication of distal ischemia and stroke.

In patients with inadvertent subclavian artery catheterization, balloon tamponade is an effective first step in management, with primary technical success approaching 100% in cases of single lumen injury. It appears less effective in patients with double lumen injury. However, the ease of transition from balloon tamponade to stent placement supports an initial attempt at hemostasis with tamponade prior to placement of a permanent stent.

Relatively small radial artery may be challenging for cannulation. We investigated whether a distal tourniquet would inflate the proximal radial artery and therefore facilitate cannulation in adults.

There were two stages of the study. The first was to measure the characteristics of radial artery by ultrasound imaging before and after tourniquet in volunteers. The second was a prospective, randomized, double blind study. Forty patients (American Society of Anesthesiologists I-III) who needed artery cannulation during operation were enrolled. Patients were assigned into two groups: loosen or tightened tourniquet for proximal radial artery cannulation by traditional palpation technique. The primary endpoints were the success rates and time of first attempt success by traditional palpation technique. The time of success after two to three attempts, failure rates and complications were collected.

For volunteers, the distal tourniquet significantly expanded the cross-sectional up-forward diameter (p<0.001) and the area (p<0.05), but had no effect on cross-sectional lateral-lateral diameter or circumference of proximal radial artery (p>0.05). The success rate of first attempt was higher in the tighten group (75%) than in the loosen group (15%, p<0.05), but the time for success of first attempt/two to three attempts was similar (19.33 ± 1.12/62.11 ± 37.03 sec loosen group vs. 19.07 ± 12.75/45.55 ± 8.98 sec tightened group, p>0.05). Both groups had same failure rates of 10%. No complication was observed.

Distal tourniquet could inflate the proximal radial artery and facilitate palpation of radial artery cannulation.