[Hyponatremia and syndrome of inappropriate ADH secretion (SIADH)]. / Iponatriemia e sindrome da inappropriata secrezione di ormone antidiuretico (SIADH).

The syndrome of inappropriate ADH secretion (SIADH), also termed ''syndrome of inappropriate antidiuresis (SIAD)'', is an often unrecognized cause of hypotonic hyponatremia, arising from ectopic release of ADH in lung cancer or as a side effect of various drugs. In SIADH, hyponatremia results from selectively impaired water excretion by the kidney, whereas the external Na+ balance is normally regulated. Despite the increase in total body water, only a slight reduction of urine output and modest edema are usually seen. Renal function and acid-base balance are generally preserved, while subclinical neurological impairment may occasionally become life-threatening, when hyponatremia has an abrupt onset. The major clinical variants of SIADH are reviewed here, with particular emphasis on causes, iatrogenic complications and hospital-acquired hyponatremia. Effective treatment of SIADH is based on water restriction, hypertonic saline plus loop diuretics, or aquaretics. Worsening of hyponatremia may result from parenteral isotonic fluid administration, emphasizing the importance of an early diagnosis and careful follow-up of these patients.

Double guidewire technique (DGT): Optimising endovascular revision of juxta-anastomotic stenosis in AV-fistulae: A retrospective analysis.

BACKGROUND: Arteriovenous fistula (AVF) is the preferred angioaccess for haemodialysis but suffers from a high stenosis rate, juxta-anastomotic stenosis (JAS) being the most frequent. Percutaneous transluminal angioplasty (PTA) of JAS would have some advantage (such as mini-invasive and vein sparing treatment), but higher recurrence rate is observed as compared to surgery. We report results of juxta anastomotic stenosis PTA using the 'double guide technique' (DGT) as described by Turmel-Rodrigues, in a selected cohort from our Vascular Access Centre. PATIENTS AND METHODS: From January to June 2018, 25 consecutive patients were treated by DGT. By means of retrograde access through the outflow vein by a 6 F introducer, two guide wires were navigated: one into proximal radial artery (GW1), the other into distal artery (GW2). GW2 was used to dilate juxta-anastomotic vein and anastomotic area with 6 mm high-pressure balloon, while by GW1 juxta-anastomotic artery was dilated with 4 mm semi-compliant balloon. Mean diameter of balloons were 6.7 and 4.1 mm for venous and arterial tract dilatation. Follow up was carried out up to 12 months. Prospectively collected data were analysed retrospectively. RESULTS: One-year primary and secondary patency was 52% and 95% respectively. Recurrence rate was 0.56 procedure/pt/year. Mean access blood flow at 12 months was 830 ml/min. CONCLUSION: Double Guidewire Technique is an effective and minimally invasive procedure. By avoiding under dilation of JAS the recurrence rate resulted quite satisfactorily in our population.

[Hypertensive crisis in kidney patients]. / Le crisi ipertensive nel paziente nefropatico.

The classification and management of hypertensive crisis have been recently reviewed in the context of both European and American guidelines. The key points for proper blood pressure control in severe arterial hypertension are: 1 - Distinction between urgent intervention and emergencies 2 - Choice of the best drug(s) 3 - Choice of the correct route of administration. In patients with renal disease, beside the common causes of hypertension/ hypertensive crises, kidney-specific causes should be taken into account such as renal parenchymal hypertension, renovascular hypertension, sclerodermic crises, and preeclampsia.

Monitoring the Patient Following Radio-Cephalic Arteriovenous Fistula Creation: Current Perspectives.

Autogenous radial-cephalic direct wrist arteriovenous fistula (RC-AVF) in the non-dominant arm is the gold standard for dialysis vascular access. However, the RC-AVF non-maturation rate is significant (≃ 40%) due to an increasingly elderly and comorbid population incidence. A detailed identification of the biological cascade underlying arteriovenous fistula (AVF) maturation could be the key to clinical research aimed at identify the group of patients at risk of primary AVF failure. Currently, careful post-operative monitoring remains the most crucial aspect to overcome the problem of impaired maturation. Up to 80% of patients with immature RC-AVF have problems potentially solvable with early endovascular or surgical correction. Physical examination by experienced practitioners in conjunction with duplex ultrasound examination (DUS) can identify physical signs of non-maturation, understand the underlying cause, and drive for a tailored early planning to treat the complication. New approaches for the early assessment of AVF maturation are under study. Techniques to promote RC-AVF maturation performed through the administration of pre-or peri-operative drugs have missed up to now to prove an efficacy in improving fistula success. The new techniques tested after surgery appear to hold future promise for improving fistula maturation.

Cubital vein transposition for a distal radiocephalic fistula complicated by outflow obstruction.

INTRODUCTION: Outflow stenosis is a frequent complication of vascular access for hemodialysis. It may cause increased pressure within the angioaccess along with reduced blood flow. Elective treatment is percutaneous transluminal angioplasty; however, when a long occlusion (>2 cm) occurs, success and mid-term patency of endovascular treatment are uncertain. We describe a case series of patients with long occlusion of elbow outflow complicating an otherwise excellent forearm arteriovenous fistula, treated by a bypass across the elbow through cubital vein transposition. PATIENTS AND METHODS: Six consecutive patients have been treated between 2015 and 2017; all were referred because of either low flow, increased venous pressure, excessive bleeding time, or recirculation and were examined by duplex ultrasound. A total of 83% of patients showed associated thrombosis within the access. All procedures were performed under loco-regional anesthesia and preventive hemostasis. Surgical thrombectomy was also performed when needed. RESULTS: Immediate success was obtained in all but two patients converted in veno-venous polytetrafluoroethylene bypass. Post-operative blood flow increased from 316 to 878 mL/min. All patients were dialyzed through the forearm access immediately the day after surgery, without the need for central vein catheter. Overall, 75% of patients needed a percutaneous transluminal angioplasty of the veno-venous anastomosis within 6 months. Primary and secondary patency at 12 and 24 months were 25%-0% and 100%-100%, respectively. CONCLUSION: Outflow reconstruction through the elbow bypass by cubital vein transposition is a valuable resource to rescue radiocephalic arteriovenous fistula complicated by outflow obstruction, avoiding the use of an interim central vein catheter. Endovascular treatment is vital to maintain functional patency in the mid- and long term.

Early echocardiographic modifications after flow reduction by proximal radial artery ligation in patients with high-output heart failure due to high-flow forearm arteriovenous fistula.

BACKGROUND: Arteriovenous fistula (AVF) for haemodialysis (HD) induces a volume/pressure overload which impairs bi-ventricular function and increases systolic pulmonary arterial pressure (PAPS) and left ventricular mass (LVM). In the presence of high blood flow (Qa) AVF (> 1.5 L/min/1.73 m2) and cardio-pulmonary recirculation (>20%), high-output congestive heart failure (CHF) may occur and AVF flow reduction is recommended. Proximal Radial Artery Ligation (PRAL) is an effective technique for distal radio-cephalic (RC) AVF flow reduction. METHODS: we evaluated six HD and four transplant patients with high-flow RC AVF and symptoms of CHF who underwent PRAL. We compared echocardiographic (ECHO) findings before (T0) and 1 and 6 months (T1,T6) after PRAL. Preoperative ECHO was performed before (T0b) and after AVF anastomosis manual compression (T0c). RESULTS: At T1 AVF flow reduction rate was 58.4% ± 13% and 80% of patients reported improved CHF symptoms. ECHO data showed an improvement of tricuspid annular plane systolic excursion (TAPSE) at T1 (p = 0.03) and a reduction of PAPS at T6 (p = 0.04). TAPSE improved after AVF anastomosis compression during preoperative ECHO (p = 0.03). Delta of TAPSE at the dynamic manoeuvre at T0 directly correlated with early (1 month after PRAL, p = 0.01) and late (6 months after PRAL, p = 0.04) deltas of TAPSE. CONCLUSIONS: AVF flow reduction after PRAL induces immediate regression of CHF symptoms, early improvement of TAPSE and late improvement of PAPS, suggesting a prevalent right sections involvement in CHF. Preoperative TAPSE modification after AVF anastomosis compression could represent a useful evaluation tool to determine which patients would benefit of PRAL.

Impaired maturation of arteriovenous fistula for haemodialysis due to forearm artery stenosis: percutaneous endovascular treatment.

INTRODUCTION: Distal autogenous arteriovenous fistula (dAVF), considered the "gold standard" vascular access for haemodialysis, suffers from a high rate of impaired maturation. One of the usual causes is low-flow associated forearm arterial stenosis. In such cases, endovascular treatment by percutaneous transluminal angioplasty represents a helpful option to enable maturation of the vascular access.Currently, there are few reports concerning the treatment of this complication. Therefore, we describe our single-centre experience based on a retrospective review of prospectively collected data. PATIENTS AND METHODS: We treated 18 consecutive patients from July 2007 to January 2014 (16 radio-cephalic, 2 ulno-basilic distal AVF). A low flow due to forearm artery stenosis was diagnosed by duplex examination, as routinely performed one month after dAVF creation. An anterograde trans-brachial access was used for a 4-mm high-pressure angioplasty of the stenosed artery. RESULTS: All interventions resulted in patent fistulas. Isolated percutaneous transluminal angioplasty (PTA) was required without need of stent placement. Mean blood flow increased from 304 mL/min, preoperatively, to 671 mL/min (p<0.01), as checked one week after the procedure. One-year primary and secondary patency were 84% ±7.3% and 92% ± 9.2%, respectively. Under no circumstances did access-induced distal ischemia occurred during follow-up. CONCLUSIONS: Endovascular approach is a helpful and minimally invasive procedure for treatment of delayed maturation of dAVF related to forearm artery stenosis.

Echographic landmark of cephalic and collateral accessory vein at forearm in preoperative evaluation for hemodialysis angioaccess.

INTRODUCTION: Superficial veins in the upper arm differ according to their relationship to the superficial fascia. We investigated the echographic landmark of the cephalic vein (CV) to correctly distinguish it from the collateral accessory vein (CAV) before hemodialysis angioaccess creation. MATERIALS AND METHOD: Twenty consecutive patients were evaluated by ultrasonographic scan. The echographic features of CV and CAV together with their relationship were described. RESULTS: Ninety-five percent of patients presented both CV and CAV (75% CAV laterally located, 25% medially located). CV and CAV diameters were 2.9 (±0.65) and 2.0 (±0.70), respectively. CONCLUSIONS: CV differs from CAV for its anatomic location at forearm. Such a difference is clearly evident under ultrasound examination, despite any recommendation in ultrasound guidelines. Whether the exclusive use of CV for angioaccess creation can lead to a better outcome will be ascertained by further studies.

Preoperative duplex examination in patients with dialysis access-related hand ischemia: indication for distal radial artery ligation.

PURPOSE: To demonstrate that treatment with distal radial artery ligation (DRAL), based on preoperative evaluation with duplex ultrasound, is effective for correction of hand ischemia related to distal radiocephalic arteriovenous fistula (AVF). METHODS: Two patients with symptoms of hemodialysis access-induced distal ischemia (HAIDI) related to radiocephalic AVF at wrist (necrotic lesion of fingers, pain at rest and loss of sensory function) were studied with preoperative duplex examination. Color Doppler ultrasound (CDU) showed low-normal flux (700 and 500 mL/min respectively), retrograde flow in the DRA and increased digital perfusion after manual occlusion of DRA. They were both treated by ligation of the DRA. RESULTS: Both patients had immediate improvement of ischemic symptoms. Reversed DRA flow disappeared and peripheral flow ameliorated. Postoperative AVF flow was 500 and 350 mL/min, stable at 16 and 8 months of follow-up, respectively. CONCLUSIONS: Preoperative CDU examination, simulating reversed DRA flow interruption, seems to be an effective tool to predict the success of DRAL procedure.

Preventive hemostasis for hemodialysis vascular access surgical reinterventions.

Surgical reinterventions for treatment of complications or ligation of haemodialysis vascular access (VA), when performed in or below the mid/lower part of the upper arm, could benefit from the use of preventive haemostasis with an inflatable tourniquet. This technique offers several advantages, such as the reduced risk of bleeding and the increased accuracy of dissection allowing for a minimally invasive approach. The use of preventive haemostasis is safe, economical and time-saving. All the secondary procedures on VA that could benefit from its use are reviewed.

Assessment of long-term vasoplegia induced by brachial plexus block: a favorable effect for hemodialysis angioaccess surgery?

PURPOSE: Loco-regional anesthesia, along with the neurosensitive inhibition causes arterial and venous vasodilatation, that could be of interest for vascular access surgery. We evaluated the long term vasoplegia persistence after brachial plexic block. METHODS: Five patients submitted to brachial plexus block for an orthopedic procedure have been observed. Both radial arteries, that of the blocked arm and the opposite as a control, were analyzed by ultrasound examination, at time 0 and 360 minutes after anesthesia induction. All patients were treated with the same anesthesiologic protocol: axillary approach, use of an electroneurostimulator, injection 10 ml of ropivacain 7.5% + 10 ml of mepivacain 2%. The parameters evaluated from the arterial ultrasound flowmetry were: peak systolic velocity (PSV), end diastolic velocity (EDV) and resistance index (RI). RESULTS: No modification of the arterial flow were observed in the control arm at 0 and 360'after block induction. The blocked arm instead showed a significant decrease of the resistive index, stable at 360 minutes. CONCLUSIONS: The vasoplegia accompaning plexic block lasted 6 hours after anesthesia induction. Whereas this longstanding haemodynamic effect is beneficial for early patency of vascular access for hemodialysis, needs to be ascertained by further investigations.