Donna Merrill

Accuracy of Physical Examination in the Detection of Arteriovenous Fistula Stenosis

BACKGROUND AND OBJECTIVES Physical examination has been highlighted to detect vascular access stenosis; however, its accuracy in the identification of stenoses when compared with the gold standard (angiography) has not been validated in a systematic manner. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A prospective study was conducted of 142 consecutive patients who were referred for an arteriovenous fistula dysfunction to examine the accuracy of physical examination in the detection of stenotic lesions when compared with angiography. The findings of a preprocedure physical examination and diagnosis were recorded and secured in a sealed envelope. Angiography from the feeding artery to the right atrium was then performed. The images were reviewed by an independent interventionalist who had expertise in endovascular dialysis access procedures and was blinded to the physical examination, and the diagnosis was rendered. Cohens kappa was used as a measurement of the level of agreement beyond chance between the diagnosis made by physical examination and angiography. RESULTS There was strong agreement between physical examination and angiography in the diagnosis of outflow (agreement 89.4%, kappa = 0.78) and inflow stenosis (agreement 79.6%, kappa = 0.55). The sensitivity and specificity for the outflow and inflow stenosis were 92 and 86% and 85 and 71%, respectively. There was strong agreement beyond chance regarding the diagnosis of coexisting inflow-outflow lesions between physical examination and angiography (agreement 79%, kappa = 0.54). CONCLUSIONS The findings of this study demonstrate that physical examination can accurately detect and localize stenoses in a great majority of arteriovenous fistulas.

Venous mapping using venography and the risk of radiocontrast-induced nephropathy.

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.

ASDIN Original Investigations: Venous Mapping Using Venography and the Risk of Radiocontrast-Induced Nephropathy

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.

Accuracy of physical examination in the detection of arteriovenous graft stenosis.

Physical examination has recently been demonstrated to detect vascular access stenosis in patients with arteriovenous fistulae. However, its accuracy in the identification of stenoses when compared with the gold standard (angiography) in patients with arteriovenous grafts has not been studied in a systematic fashion. We conducted a prospective study to examine the accuracy of physical examination in the detection of stenotic lesions when compared with angiography. Forty‐three consecutive cases referred for an arteriovenous graft dysfunction were included in this analysis. Preprocedure physical examination was performed. The findings of the examination and diagnosis were recorded and secured in a sealed envelope. Angiography from the feeding artery to the right atrium was performed. The images were reviewed by an independent interventionalist with expertise in endovascular dialysis access procedures and the diagnosis was rendered. The reviewer was blinded to the physical examination. Cohen’s Kappa was used as a measurement of the level of agreement beyond chance between the diagnosis made by physical examination and angiography. There was a strong agreement between the physical examination and the angiography in the diagnosis of vein‐graft anastomotic stenosis (kappa = 0.52). The sensitivity and specificity for this lesion was 57% and 89%, respectively. There was a moderate agreement beyond chance regarding the diagnosis of intragraft (kappa = 0.43) and inflow stenoses (kappa = 0.40). The sensitivity and specificity for the intragraft and inflow stenosis was 100%, 73% and 33%, 73%; respectively. The findings of this study demonstrate that physical examination can assist in the detection and localization of stenoses in arteriovenous grafts.

Stent Graft Infection and Protrusion Through the Skin: Clinical Considerations and Potential Medico-Legal Ramifications

Stent grafts have been used for a variety of arteriovenous access associated issues. This article presents three cases of stent graft infection and a case of protruded metal piece of the stent graft through the skin. All four required surgical treatment and three cases required a tunneled dialysis catheter to provide long‐term dialysis therapy. This report highlights that stent graft problems can occur that may result in loss of the access. Additionally, strut protrusion can pose a medical hazard to those performing preparation and cannulation of the arteriovenous access.

Impact of Surgeon Selection on Access Placement and Survival Following Preoperative Mapping in the “Fistula First” Era

According to the “Fistula First Initiative” surgeon selection should be based on best outcomes, willingness, and ability to provide access services. This analysis presents arteriovenous access placement and outcomes in 75 patients when surgery was performed by one of two dedicated high‐volume vascular access surgeons (community [surgeon I] and academic medical center [surgeon II]). Preoperative vascular mapping was performed in all the patients. Demographic characteristics were similar except that patients referred to surgeon I (n = 40) were older (52.7 ± 16.2 years vs. 45.4 ± 13.7 years; p = 0.04) and tended to have more previously failed accesses (50% vs. 29%; p = 0.06) and black race (65% vs. 43%; p = 0.055) including a history of previously failed accesses (50% for surgeon I and 29% for surgeon II; p = 0.06). Similarly, there was no significant difference in the size of forearm ([surgeon I: 2.0 ± 1.0 mm], [surgeon II: 1.9 ± 0.8 mm]; p = 0.45) or upper arm veins (cephalic vein: surgeon I = 3.2 ± 1.4 mm, surgeon II = 2.9 ± 1.2 mm, p = 0.34; basilic vein: surgeon I = 5.0 ± 1.2 mm, surgeon II = 4.7 ± 1.3 mm, p = 0.25). Fistulae placement occurred in 98% vs. 71% (p = 0.001) for surgeon I and II, respectively. Characteristics predictive of fistula placement over an arteriovenous graft were surgeon selection (odds ratio [OR] = 19.52; p = 0.01) and no history of diabetes (OR = 7.61; p = 0.016). Kaplan–Meier analysis revealed 6 and 12 months overall access survival rates of 82%, 58% and 82% and 47% for surgeon I and II, respectively (p = 0.007). This analysis demonstrates that surgeon selection can have a significant impact on the rate of fistula placement and its overall survival despite similar findings on preoperative vascular mapping.

A Novel Technique for Tethered Dialysis Catheter Removal Using the Laser Sheath

Traction and cutdown techniques can successfully remove a tunneled dialysis catheter (TDC) in a great majority of patients. However, these methods may not be successful in patients with catheters that are tethered or attached to the central veins or the atrium. A forceful application of traction can lead to catheter breakage with subsequent retention of the broken piece and carries a potential risk of vascular and atrial wall avulsion. Open thoracotomy has been employed to remove an attached TDC. However, this procedure is invasive and bears a significant morbidity. This report presents three cases of tethered TDCs that underwent laser sheath extraction. The TDCs had been in place for an average of 26 months. The patients underwent initial unsuccessful removal attempt using the traction method with surgical exploration all the way to the venotomy site. The laser technique that is used to remove pacemaker/implantable cardioverter defibrillator leads was then applied to these stuck catheters. All three catheters were successfully removed without any damage to the catheter, central veins, or the right atrium. There were no retained catheter fragments left in the central veins or the atrium. One patient demonstrated a significant thrombus that extended from the tip of the catheter all the way to the right ventricle. The external sheath of the laser device successfully aspirated the thrombus. There were no procedure‐related complications. In this small series, a laser sheath successfully extracted tethered dialysis catheters. The study found the procedure to be effective, easy to perform, and minimally invasive. We suggest that this approach be considered for the removal of tethered catheters that cannot be removed using traditional approaches.

Creation of secondary arteriovenous fistulas: maximizing fistulas in prevalent hemodialysis patients.

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF‐DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow‐up of 4.8 ± 1.4 months in post‐AVG cases and 5.6 ± 1.7 months in the post‐AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.

Hemodialysis vascular access: percutaneous interventions by nephrologists.

Traditionally hemodialysis vascular access‐related procedures have been almost exclusively performed by surgeons and interventional radiologists. In recent years, nephrologists have taken the initiative of performing these procedures themselves. Because of their unique clinical perspective on dialysis access and better understanding of the intricacies of renal replacement therapy, nephrologists are ideally suited for this activity. This approach has minimized delays, decreased hospitalizations, and decreased the use of temporary catheters, thereby improving medical care, decreasing costs, and increasing patient convenience. Vascular access‐related procedures commonly performed by nephrologists include percutaneous balloon angioplasty, thrombectomy, and tunneled hemodialysis catheter‐related procedures. In addition, using vein obliteration and percutaneous balloon angioplasty techniques, nephrologists have recently documented successful salvage of arteriovenous fistulas that had failed to mature, whereas traditionally these fistulas have frequently been abandoned. While the performance of these procedures by nephrologists offers many advantages, appropriate training in order to develop the necessary procedural skills is critical. Recent data have emphasized that a nephrologist can be successfully trained to become a competent interventionalist. In addition to documenting excellent outcome data, multiple reports have demonstrated the safety and success of interventional nephrology. This review focuses on hemodialysis access‐related procedures performed by nephrologists and calls for a proactive approach in optimizing this aspect of patient care.

Modification of the peritoneoscopic technique of peritoneal dialysis catheter insertion: experience of an interventional nephrology program.

Bowel perforation is a well‐recognized complication of peritoneal dialysis catheter insertion and is associated with increased morbidity and cost of medical care. In this article we describe our 2‐year experience (August 2001–October 2003) with a modified peritoneoscopic technique of peritoneal dialysis catheter insertion to minimize the incidence of bowel perforation. Seventy patients underwent 82 consecutive peritoneal dialysis catheter insertions using the innovative technique. The modified technique is very similar to the traditional peritoneoscopic procedure except for the following differences. To gain access to the peritoneal cavity, a Veress insufflation needle (Ethicon Endo‐Surgery Inc., Cincinnati, OH) is utilized instead of the trocar. In contrast to the sharp tip of the trocar, the Veress needle has a blunt, self‐retracting end. In addition, the Veress needle is only 14 gauge as opposed to the 2.2 mm diameter of the trocar. Upon introduction of the Veress needle into the abdominal cavity, two “pops” are discerned similar to the trocar. After introduction, 400–500 cc of air are infused and the needle is removed. The infusion of air creates a space between the peritoneal surface of the anterior abdominal wall and the bowel loops. At this point, the cannula with trocar is inserted into the space created. The rest of the steps of the procedure are the same as the traditional peritoneoscopic technique. Utilizing the innovative technique, all 82 catheter insertions were performed successfully without a single bowel perforation. No other complications except for catheter migration (n = 2) were noted. The extra cost of the needle (