Ulno-basilic arteriovenous fistulae: indications and surgical technique.

Ulnar-basilic fistula is a vascular access option for hemodialysis first reported in 1967. There is no inherent reason why the ulnar artery cannot be used to create a fistula at the wrist; however, a few reports dealing with its complications and survival rates have been published in the literature. In the present work the results of 9 ulnar-basilic fistulae done in 9 adults patients on chronic hemodialysis, are reported. Two fistulae were created as primary access and the remaining 7 fistulae as secondary access after thrombosis of an ipsilateral and controlateral radiocephalic fistula in 6 cases and in a case of high-flux brachiocephalic fistula. No episodes of surgical complications were observed. This fistula is an additional option to create a distal vascular access for hemodialysis before constructing a proximal access.

Dialysis catheter associated cardiac tamponade: quick diagnosis by extemporaneous echocardiography.

We report a case of pericardial tamponade associated with over the wire exchange of a central venous catheter (CVC) for hemodialysis (HD). The complication was quickly diagnosed due to an extemporaneous echocardiogram with a linear probe, before other laboratory and radiologic tests could detect it. The described approach allowed a suitable therapy with a positive result.

Formation of self-organized nanoparticles by lecithin/chitosan ionic interaction.

In this work the production of auto-assembled nanoparticles obtained by the mixing of chitosan and lecithin is presented. The size and surface charge of the nanoparticles were studied as function of the weight ratio between components, the viscosity of the polysaccharide and the pH of the colloidal suspension. In order to elucidate the structure of nanoparticles, micro-FT-IR and elastic neutron scattering experiments have been performed. Results evidenced a strong electrostatic interaction between components and a structure that is neither that of homogeneous spheres nor of coated unilamellar vesicles. Preliminary encapsulation experiments with progesterone, as model lipophilic drug, showed good encapsulation efficiencies.

The self-locating catheter: review and cost analysis.

The self-locating catheter invented by Nicola Di Paolo has been increasingly used in Italy and elsewhere since 1994, with about a thousand patients currently implanted every year. Twelve grams of tungsten inserted in the tip of the conventional Tenckhoff catheter during extrusion do not significantly change its form, but suffice to keep the tip firmly in the Douglas cavity. The validity of the new catheter is confirmed by a multicentric controlled study in a large population of peritoneal dialysis patients. This trial showed that patients with the new catheter have fewer episodes of peritonitis, tunnel infection, cuff extrusion, catheter malfunction, obstruction and leakage. This paper outlines the present situation and reports a comparative analysis of the costs of Tenckhoff and self-locating catheters.

QENS investigation of the dynamics of starch saccharides.

We present here quasi-elastic neutron scattering results on D20 hydrated samples of amylose, one of the main saccharide components of starch. Two different sample hydrations (h = 0.5 and 1.0 g D2O (g dry amylose)-1 have been investigated in the temperature range 170 to 350 K. Below 260 K only an elastic contribution is present in the spectra, while a quasi-elastic component shows up above this temperature. The elastic incoherent structure factor (EISF) associated with this component changes considerably with increasing temperature. For the sample with hydration h = 0.5 the confinement volume increases by a factor of four in going from 300 to 350 K, and the proportion of hydrogen involved in the confined diffusion motion increases as well from 30 to 55%. Similar effects are observed at the higher hydration investigated. The observed dynamics can be associated with the known plasticising role of water in polysaccharides.

Mean square fluctuations of hydrogen atoms and water-biopolymer interactions in hydrated saccharides.

We have used the elastic neutron scattering technique to investigate the dynamics of the two main saccharidic components of starch: amylose and amylopectin. The measurements were carried out in the temperature range of 20 to 320 K and at different hydration levels from the dry state up to 0.47 g saccharide/g D(2)O. In the dry samples, the atomic dynamics is harmonic up to approximately 300 K. In the hydrated samples a "glass-like" transition leading to an anharmonic dynamics is observed. The onset of the anharmonicity occurs at temperatures that increase from approximately 180 K to 260 K upon decreasing hydration from 0.5 to 0.1 g saccharide/g D(2)O. This behavior is qualitatively similar to that observed in hydrated globular proteins, but quantitative differences are present. Assuming a simple asymmetric double-well potential model, the temperature and hydration dependence of the transition have been described in terms of few physical parameters.

Ultrasound-guided cannulation and endocavitary electrocardiography placement of internal jugular vein catheters in uremic patients: the importance of routine chest X-ray evaluation.

The NKF-DOQI guidelines recommend performing chest-X-ray(CXR) after subclavian and internal jugular vein insertion prior to catheter use. This is to exclude complications such as a pneumothorax before starting hemodialysis. Indication of a central venous dialysis catheter was based on the historic use of the subclavian vein for placement of these catheters and upon the reported incidence of pneumothorax after this approach of between 1% to 12.4%. In contrast, the incidence of these complications using the internal jugular vein (IJV) is much lower (< 1%). We report our experience in ultrasound-guided cannulation of the right IJV for dialysis vascular access in 527 uremic patients and central catheter placement by endocavitary electrocardiography (EC-ECG). Fluoroscopy was not utilized. In the first hundred cases, all patients underwent CXR. Subsequently, because of total absence of complications and catheter tip malpositioning, the CXR control was carried out only in selected cases (repeated cannulation of the jugular vein or absence of P wave). We believe that only in selected cases should a pCXR be performed before starting hemodialysis sessions, and that our method using the right IJV, ultrasound-guided puncture of the vessel, and catheter placement by EC-ECG is a safe and simple technique that avoids the need for CXR control.

Central venous catheter placement in hemodialysis: evaluation of electrocardiography using a guide-wire.

Internal jugular vein cannulation has become a routine and clinically important aspect of medical care in hemodialysis patients. Mismanagement in the location of a central venous catheter may occur in up to 20% of cases. The aim of the study was to evaluate the utility of endocavitary electrocardiography in right internal jugu-lar vein placement of central venous catheters. We examined 327 central venous catheterizations performed in two Dialysis Units; all catheters were positioned using intra-atrial ECG monitoring by guide-wire and after, by catheter filled with NaCl solution. EC-ECG via guide-wire was successful on 321 occasions (98.1%). Correct placement of the catheter was confirmed by EC-ECG via catheter in each case, and by plain chest-X-ray only in the first hundred cases. In 314 patients (98.1%), insertion of the catheter was successful at the first attempt. In 6 catheterizations, no atrial trace was obtained due to atrial fibrillation in 4 cases, and in 2 cases technical error and guide-wire looping into a right jugular vein. Complications as a direct result of guide-wire or catheter placement were not observed. In our opinion this method can be used safely and makes radiological control usually unnecessary. (The Journal of Vascular Access 2001; 2: 45-50).

Experience using a new vascular port access device for hemodialysis: preliminary clinical results.

A new subcutaneous device (Dialock(R), Biolink Corp, Middleboro, MA) provides vascular access to patients who require hemodialysis. The device consists of a port implanted in a subcutaneous pocket in the thoracic area 10 cm below the clavicle. Interdialytic patency is maintained using a priming antithrombotic solution. The device was implanted in 10 outpatients under local anesthesia, and immediately used for he-modialysis. The catheters have been used up to now for a total of 1,480 days ( 24- 248 days), the average being 4.8 months (1-8 months). Survival rate of Dialock (R)was 100% at 8 months. During this period, the device achieved prescription hemodialysis blood flow rates averaging 250-300 ml/min with a venous pressure of 180 +/- 25 mmHg. Malpositioning of the catheters due to their excessive length was observed in the first three patients and led to the repositioning of the catheters' distal tips under local anesthesia. Secondary and delayed hematoma surrounding the Dialock(R)device were observed in 2 patients one or two days after insertion. In one case, a hematoma was surgically removed under local anesthesia. Antibiotic therapy was administered for safety and prophylactic reasons. In one patient spontaneous catheter fracture and distal tip embolization occurred on the 49th day after repositioning. Percutaneous radiological retrieval of the catheter fragment was performed. No infection of the Dialock (R)device occurred and only one episode of bacteremia was observed. Blood cultures were positive for Staphylococcus epidermidis . Infection was cured by appropriate systemic antibiotic therapy combined with gentamicin and sodium citrate lock. The device was well accepted by patients and staff. The Dialock (R)device catheter offers a new vascular alternative for dialysis that deserves further long-term study. In particular, the confidence of structural materials should be tested.

Ultrasound-guided cannulation of the femoral vein for acute hemodialysis access with silicone catheters.

The percutaneous femoral approach for temporary central venous hemodialysis access is a mandatory part of patient management in many clinical settings. It is usually achieved with a blind, exter-nal landmark-guided technique. The aim of this study is to evaluate whether an ultrasound technique can improve on the external landmark method. From 1990 to January 2000, cannulation of the femoral vein was performed on 230 patients (125 male, 105 female, mean age 72 years, range 52-95 years) for temporary vascular access for hemodialysis (172 patients with acute renal failure and 58 patients in end-stage renal disease), using landmark localization with semi-rigid, uncuffed catheters. Between January 2000 and February 2001, ultrasound-guided can-nulation of the femoral vein was utilized in 38 patients (20 male, 13 female, mean age 71 , range 55-93 years) for temporary vascular access for hemodialysis (28 patients with acute renal failure and 10 patients in end-stage- renal failure). Uncuffed, dual-lumen silicone catheters were used. Cannulation of the femoral vein was achieved in 100% of cases using ultrasound, and in 87% using the landmark-guided technique. Using ultrasound, puncture of the femoral artery occurred in 2.6% of patients, and hematoma in 0%. Using the 'blind' technique, puncture of the femoral artery occurred in 11.2% of patients, and hematoma in 3.9%. The average catheter dwell time, in accordance with NKF-DOQI guidelines, was 5 days (range 2 - 14 days) for semi-rigid catheters and 45 days (range 5-120 days) for silastic catheters. The number of complications rose significantly in the patients with semi-rigid catheters. In this group, local exit infection occurred in 105 persons (45% of cases), total catheter thrombosis in 46 (20%), bacteriemia in 28 (12%), and phlebitis of the leg in 6 (2.6%). In the group with silicone catheters local exit infection occurred in 4 patients (10 % of cas-es), total catheter thrombosis in 1 (2.6%), bacteriemia in 2 (5.2%) and phlebitis in 0 (0%). The result of the study suggests that ultrasound-guided cannulation of the femoral vein is superior to traditional techniques relying on anatomic landmark; it reduces the numbers of unsuccessful attempts and the possible acute complications of the procedure. We believe that femoral cannulation with modern flexible silicone catheters can be considered as a reliable temporary access, even for extended periods.

Real-time ultrasound and endocavitary electrocardiography for venous catheter placement.

The authors report on their experience with internal jugular vein catheterization with temporary and tunnelled cuffed hemodialysis catheters in 527 patients from 1991 to 2001, using ultrasound guidance and monitoring of catheter placement by endocavitary electrocardiography. The incidence of successful puncture and cannulation using ultrasound was 99.62%. The majority of patients had catheters inserted on the first pass (93%) and fewer attempts were required (range, 2 to 5). In the first year of the procedure in 1991, we observed two cases of accidental puncture of the carotid artery because of an error in ultrasound localization of the neck vessel. Arrhythmias were not observed during this procedure. Right atrial electrocardiography was successful on 504 occasions (96.83%), and correct catheter placement was confirmed by plain chest-X-ray in the first 100 patients. The results confirm that real-time ultrasound guidance for catheter insertion is superior to tradi-tional techniques relying on anatomic landmarks and should be adopted as the standard of care. Ultrasound guidance and EC-ECG improves both the success and the safety of internal jugular catheter insertion. The authors propose that EC-ECG be validated as a technique in compliance with recent Food and Drug Ad-ministration guidelines regarding the location of central venous catheter tips.

Anatomical variations of the internal jugular vein in non-uremic outpatients.

The internal jugular vein (IJV) should be the preferred form of venous vascular access for the placement of dialysis catheters. 'Blind' puncture or 'skin mark' ultrasound technique puncture present multiple complications due to the significant variations in IJV location in normal subjects and even more so in uremic pa-tients. The aim of this study is to demonstrate the important rate of IJV site variations in a random healthy pop-ulation. We tested 450 subjects (244 male, 206 female) in our hospital Ultrasound Ambulatory using an Ansaldo AUS ul-trasound device with linear 10 MHz probe on both sides at the Sedillot triangle level and noticed the relations between IJV and carotid artery course. The most frequent location of IJV was the anterior lateral (79.3% on the right side, 83.5% on the left). The re-maining options were lateral, anterior, posterior-lateral, anterior-medial. We found no significant difference in IJV diameter on either side of the neck. We therefore consider IJV puncture with ultrasound guidance to be the first choice in central venous cannulation for hemodialysis treatment. This procedure helps avoid incorrect puncture of the carotid artery related to its abnormal location.

Implantation of permanent jugular catheters in patients on regular dialysis treatment: ten years' experience.

Dual-lumen cuffed central venous catheter proved an important alternative vascular access compared to conventional arteriovenous (Cimino-Brescia) shunt in a selected group of patients on regular dialysis treatment. Typically, these catheters are used as bridging access, until fistula or graft is ready for use, or as permanent access when an arteriovenous fistula or graft is not planned (NKF-DOQI). We conducted a prospective study on IJV permanent catheter insertion and its related earlier and long-term complications. From February 1991 to February 2001 we inserted in 124 patients in end stage renal disease 135 cuffed catheters (130 in the right IJV and 5 in the left IJV), 92 of which were Permcath, 27 Vascath, and 16 Ash-Split. We performed the insertion of catheters by puncturing the IJV under ultrasonographic guid-ance in the lower side of the Sedillot triangle and checking the accurate position of the tip by endocavitary electrocardiography (EC-ECG). The duration of catheter use was from 60 to 1460 days, mean 345 days. The actuarial survival rate at 1 year was 82%, at 2 years 56%, at 3 years 42% and at 4 years 20%. The exit site infection and septicemia rates were 5.2 and 2.86 per 1000 catheter days respectively. Catheter sepsis was implicated in the death of three patients, all of whom had multiple medical problems. Several episodes of thrombosis (6% of dialyses) occurred which required urokinase treatment, and catheter replacement in 12 patients (9.6%). In 3 cases the catheters were displaced and correct repositioning was performed. Two catheters (Ash-Split) were replaced due to accidental damage of the external portion of catheters (alcoholic disinfectant). Catheter tip embolism occurred on one occasion during elective catheter exchange over guide-wire. One of the common problems encountered with cuffed tunneled catheters is poor blood flow, most often secondary to the formation of a fibrin sheath around the lumen. Even if we conducted a non-randomized study, in our experience, the higher rate of malfunctioning catheters was in the group with no anticoagulation therapy. Therefore, we suggest anticoagulation treatment in all patients wearing central vascular catheters with no contraindication. Just one year ago, we followed NKF-DOQI clinical practice guidelines for vascular access that indicated that for patients who have a primary AV fistula maturing, but need im-mediate hemodialysis, tunneled cuffed catheters are the access of choice and the preferred insertion site is the right IJV. Considering recent reports of permanent central venous stenosis or occlusion after IJV can-nulation, currently, our first choice is femoral vein cannulation with smooth silicone rubber catheters, tunneled if long-term utilization is needed (more the 3-4 weeks). In our opinion, the right IJV puncture is to be avoided as much as the venipuncture of arm veins suitable for vascular access placement, particularly the cephalic vein of the non-dominant arm. Our data confirm that permanent venous catheters might rep-resent an effective long-term vascular access for chronic hemodialysis, particularly for older patients with cardiovascular disease and for cancer patients.

Accidental migration of ASH-split catheter during central venous catheter replacement: retrieval using an interventional radiology approach.

Catheter fracture and embolization of the distal fragment are well-known complications of subclavian central venous long-term cannulation. In hemodialysis it is an exceptional event. We report a case of accidental rupture of a cuffed hemodialysis catheter with distal migration of a fragment during a procedure of catheter exchange via guide-wire. According to most reported cases, intravascular catheter separation usually occurs completely asymptomatically; our report confirms that catheter embolization itself is usually asymptomatic. Less than one third of the literature-reported cases have associated symptoms, such as palpitations or chest discomfort. Once diagnosed, treatment is an interventional radiological approach, which has a very high success rate. The replacement of permanent cuffed hemodialysis catheters via guide-wire is a delicate procedure and if catheter embolization is diagnosed, the patient must be referred to a center with specific experience in the retrieval of intravascular objects.

The placement of central venous catheters in hemodialysis: role of the endocavitary electrocardiographic trace. Case reports and literature review.

At present, the placement of a central venous catheter is becoming more and more a routine procedure nevertheless it involves different operators in fields such as oncology, nutrition, nephrology, and emergency medicine. It is well known that complications in the placement of CVC may occur in up to 20% of cases. One fifth of the catheters may result to be misplaced either in the internal omolateral jugular vein or in the innominate vein or in the controlateral brachiocephalic veins and usually a chest radiogram is necessary to evaluate its location. On the basis of 10 years of experience including more than 1,000 CVC placements, we now believe that endocavitary electrocardiography EC-ECG, initially studied and applied by Dr. Serafini, constitutes the best technique, more secure and more comfortable for the patient, to verify the position of the tip of a CVC. The technique EC-ECG, very simple and secure, utilizes the CVC as an endocavitary electrode. This is connected to a standard electrocardiograph, the same one to which the patient is connected during the placement of the CVC, and provides, in derivation V 1 or D 3 , an electrocardiographic pattern extremely sensitive to the position of the catheter tip. From December 1991 to December 2000, this technique has been used successfully in our departments of nephrology and applied to 1,139 patients that needed a CVC for hemodialysis. EC-ECG and a standard chest radiogram controlled the first 100 CVC we placed and in the other 1,039 cases, the control was made by EC-ECG alone. Only in 31 patients (2.7% of all cases), due to arrhythmia, the technique EC-ECG was not utilized. According to our experience, the procedure EC-ECG is an extremely reliable technique, sensitive and specific in 100% of cases, easy for the operator to perform, comfortable for patient. It doesn't need additional time to be performed and eliminates the need of taking a chest radiogram that up to now was considered indispensable in order to verify the position of the catheter tip. In this manner serious complications such as pneumothorax, and haemothorax that can complicate the placement of a CVC can also be avoided. Based on our experience, we now believe that this technique, that today has a large application in nephrology, oncology, clinical nutrition and in various branches of general medicine whenever the placement of a CVC is required, should be considered as a possible new guide line in controlling the placement of a CVC together with a chest X-ray when it is necessary.