[Calcified Fibrin Sheath After Stuck Catheter Removal: Case Report and Literature Review].

The prevalence of central venous catheters (CVC) in hemodialysis patients is around 20-30%. In this scenario, complications related to the use of the CVC are commonly observed, requiring active management by nephrologists. These include infectious complications as well as those related to CVC malfunction. Among the latter, the formation of a fibrin sheath around the catheter linked to foreign body reaction could cause CVC malfunction in various ways. Even after the removal of the catheter, the fibrin sheath can remain inside the vascular lumen (ghost fibrin sheath) and rarely undergo calcification. We describe the clinical case of a hemodialysis patient who, following the removal of a malfunctioning, stuck CVC, presented a calcified tubular structure in the lumen of the superior vena cava, diagnosed as calcified fibrin sheath (CFS). This rare occurrence, described in the literature in 8 other cases, although rare, is certainly underdiagnosed and can lead to complications such as sepsis resulting from CFS, pulmonary embolisms, and vascular thrombosis. Therapeutic approaches should be considered only in symptomatic cases and involve an invasive surgical approach.

[Triple stenosis of brachio-basilic arteriovenous fistula: percutaneous transluminal angioplasty utility, case report and literature review].

The major haemodialysis arteriovenous fistula (AVF) complication is stenotic disease. It is represented by a reduction of the arterial or venous caliper forming the AVF. Most frequently it is located in the juxta- anastomotic region of the venous segment. There are a lot of mechanisms responsible for the stenosis formation; some are correlated by the shear stress in the wall of venous tract with a lot of biochemical mechanisms, others are associated with the repetition of venipuncture during haemodialisys treatment. It is recommended that each dialysis center activate an AVF monitoring program capable of identifying and treating stenosis. We describe a clinical case of a young woman with a multiple stenosis disease of a brachio-basilical transposed AVF.

CEUS-guided PTA on stenotic AVF: Morphological and functional point of view.

BACKGROUND: Stenosis represents the main cause of hemodialysis fistula malfunction. The ultrasound-guided angioplasty with ecographic contrast (CEUS) could provide further advantages to the classical ultrasound guided method improving the morphological characterization of the stenosis and providing quantitative data with the creation of time intensity curves (TIC) collecting functional data comparable between pre and post procedure. METHODS: A total of 10 CEUS-guided angioplasties were performed on malfunctioning fistulas. The sonographic contrast medium was injected into the vascular tree trough the introducer. Morphological and functional data nature were collected. Were generated TIC curves, obtained by positioning a ROI in correspondence with the post-stenotic tract of the efferent vein. The data collected, regarding the peak intensity reached by the signal (PI) and the time to reach the peak signal intensity (TTP), were compared in the pre and post-procedural phase with flow of vascular access (Qa) and resistance indices (RI). RESULTS: Statistically significant correlation (p < 0.05) was observed between Qa and TTP (r = 0.77; p = 0.009), RI and TTP (r = 0.71; p = 0.02), Qa and PI (r = 0.86; p = 0.0012), and between RI and PI (r = 0.88; p < 0.001). CONCLUSION: In addition to the advantages associated with the use of ultrasound contrast medium in improving the visualization and characterization of the stenosis by facilitating the PTA procedure, the functional data deriving from the quantitative analysis provide new parameters for evaluating the success of the procedure which could also be used as predictive markers of stenosis recurrence together with the classical ones.

[Sonographic artifacts in nephrology].

The huge spreading of sonography in the field of nephrology led to the use of more performant equipment with construction of better quality images, but with an unfavorable signal/noise ratio, that bring to the generation of artifacts: false signals which creates images not corresponding to reality. Interaction between ultrasounds and biological structures generates a lot of physical phenomena: reflection, dispersion, absorption and diffraction; these elements create not only the images but also the artifacts. The artifacts, which don't correspond to anatomic reality, could be related to the extreme difference of acoustic impedance between the biological structures, or to an error in the settings of B-Mode and color-doppler functions. Sometimes they can be dangerous and make a diagnosis hard, but most of the time they are useful and pathognomonic of a lesion or physiologic structure. It's fundamental for the sonographer being able to discern between real to artifact; the rule is that everything that is repeated in all scans with different insonation angles is true, while what is not repeated in all scans can be an artifact.

[Parameters predicting arterious-venous fistula maturation in pre surgery vascular mapping].

Arterious-venous fistula (AVF) represents the first-choice vascular access for haemodialysis. Pre-surgery evaluation is mandatory to identify the appropriate vessels and to predict the success of AVF creation. Echo-color Doppler provides a wealth of morphological and functional values useful to create an optimal vascular access for haemodialysis. The purpose of this study has been to identify pre-surgery echo-color Doppler parameters useful to predict AVF maturation. 44 patients were enrolled, and 44 AVF created. During pre-surgery evaluation we collected the following data: cephalic vein and radial artery calibers; radial artery flow and caliber; flow and resistive index (RI) of the brachial artery. We also performed a reactive hyperemia test. During the post-surgery evaluation after 30 days, we collected: AVF flow; resistive index of the brachial artery; post-anastomosis cephalic vein caliber. The results showed a direct correlation between AVF flow and some parameters: cephalic vein, radial artery and brachial artery caliber, reduction of RI after reactive hyperemia test and, in the post-surgery evaluation, between AVF flow and post-anastomosis cephalic vein caliber. We divided patients into two groups: "A", representative of AVF adequate maturation, and "B", representative of AVF early failure (EF) and AVF failure to mature (FTM). We observed some statistically significant differences in the two groups. With the creation of Receiver Operating Characteristic (ROC) curves we identified two parameters able to predict the AVF outcome (Δ IR = 0.15; Δ flow = 150 ml/m). This study identifies pre-surgery echo-color Doppler parameters that could be useful, together with others, to predict the outcome of the AVF creation.

What volume to choose to assess online Kt/V?

INTRODUCTION: Urea distribution volume (V) can be assessed in different ways, among them the anthropometric Watson Volume (VW). However, many studies have shown that VW does not coincide with V and that the latter can be more accurately estimated with other methods. The present multicentre study was designed to answer the question: what V to choose to assess online Kt/V? MATERIALS AND METHODS: Pre- and postdialysis blood urea nitrogen concentrations and the usual input data set for urea kinetic modelling were obtained for a single dialysis session in 201 Caucasian patients treated in 9 Italian dialysis units. Only dialysis machines measuring ionic dialysance (ID) were utilized. ID reflects very accurately the mean effective dialyser urea clearance (Kd). Six different V values were obtained: the first one was VW; the second one was computed from the equation established by the HEMO Study to predict the single pool-adjusted modelled V from VW (VH) (Daugirdas JT et al. KI 64: 1108, 2003); the others were estimated kinetically as: 1. V_ID, in which ID is direct input in the in the double pool variable volume (dpVV) calculation by means of the Solute-solver software; 2. V_Kd, in which the estimated Kd is direct input in the dpVV calculation by means of the Solute-solver software; 3. V_KTV, in which V is calculated by means of the second generation Daugirdas equation; 4. V_SPEEDY, in which ID is direct input in the dpVV calculation by means of the SPEEDY software able to provide results quite similar to those provided by Solute-solver. RESULTS: Mean± SD of the main data are reported: measured ID was 190.6 ± 29.6 mL/min, estimated Kd was 211.6 ± 29.0 mL/min. The relationship between paired data was poor (R2 = 0.34) and their difference at the Bland-Altman plot was large (21 ± 27 mL/min). VW was 35.3 ± 6.3 L, VH 29.5 ± 5.5, V_ID 28.99 ± 7.6 L, V_SPEEDY 29.4 ± 7.6 L, V_KTV 29.7 ± 7.0 L. The mean ratio VW/V_ID was 1.22, (i.e. VW overestimated V_ID by about 22%). The mean ratio VH/V_ID was 1.02 (i.e. VH overestimated V_ID by only 2%). The relationship between paired data of V_ID and VW was poor (R2 = 0.48) and their mean difference at the Bland-Altman plot was very large (- 6.39 ± 5.59 L). The relationship between paired data of V_ID and VH was poor (R2 = 47) and their mean difference was small but with a large SD (- 0.59 ± 5.53 L). The relationship between paired data of V_ID and V_SPEEDY was excellent (R2 = 0.993) and their mean difference at the Bland-Altman plot was very small (- 0.54 ± 0.64 L). The relationship between paired data of V_ID and V_KTV was excellent (R2 = 0.985) and their mean difference at the Bland-Altman plot was small (- 0.85 ± 1.06 L). CONCLUSIONS: V_ID can be considered the reference method to estimate the modelled V and then the first choice to assess Kt/V. V_SPEEDY is a valuable alternative to V_ID. V_KTV can be utilized in the daily practice, taking also into account its simple way of calculation. VW is not advisable because it leads to underestimation of Kt/V by about 20%.

[HELLP syndrome and hemolytic uremic syndrome during pregnancy: two disease entities, same causation. Case report and literature review].

Thrombotic microangiopathies (TMA) are a group of diseases that can complicate pregnancy and threaten the lives of both the mother and the fetus. Several conditions can lead to TMA, including thrombotic thrombocytopenic purpura (TTP), HELLP syndrome and hemolytic uremic syndrome (HUS). We describe the case of a 39-year-old woman who presented a HELLP syndrome in the immediate postpartum period. The patient had acute kidney injury (AKI), increased LDH, unmeasurable haptoglobin levels and hypocomplementemia. Her ADAMTS13 value was normal, thus ruling out TTP. Shiga toxin tests were negative, so HUS associated with E. coli was also ruled out. HELLP syndrome and atypical hemolytic-uremic syndrome (aHUS) remained the most probable diagnosis. In the days following childbirth, the patient's transaminase and bilirubin levels normalized while the anemia persisted, as did the AKI, resulting in the institution of dialysis treatment. A diagnosis of aHUS was made and therapy with eculizumab was started. The patient's blood counts progressively improved, urine output was restored, her indices of renal function also concomitantly improved and dialysis was interrupted. A rash appeared after the third administration of eculizumab and the treatment was suspended. The patient is currently being followed up and has not relapsed. At thirteen months after delivery her renal function is normal as are her platelet counts, LDH, haptoglobin levels and proteinuria. Tests for mutations in the genes that regulate complement activity were negative. We believe that childbirth triggered the HELLP syndrome, which in turn brought about and sustained the HUS. In fact, the patient's liver function improved right after delivery, while her kidney injury and hemolysis persisted, and she also had an excellent response to eculizumab. To our knowledge, no other cases of HELLP syndrome associated with haemolytic uremic syndrome during pregnancy have been reported in literature, nor have cases in which treatment with eculizumab was limited to only three administrations.