Raphael M Cohen

Hospital of the University of Pennsylvania, Philadelphia, PA, United States

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Publications (6)16.49 Total impact

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    ABSTRACT: Over-the-wire exchange of tunneled dialysis catheters is the standard of care per K/DOQI guidelines for treating catheter-related bacteremia. However, Gram-positive bacteremia, specifically with staphylococcus species, may compromise over-the-wire exchange due to certain biological properties. This study addressed the effectiveness of over-the-wire exchange of staphylococcus-infected tunneled dialysis catheters compared with non-staphylococcus-infected tunneled dialysis catheters. Patients who received over-the-wire exchange of their tunneled dialysis catheter due to documented or suspected bacteremia were identified from a QA database. Study patients (n = 61) had positive cultures for Staphylococcus aureus, Staphylococcus epidermidis, or coagulase-negative staphylococcus not otherwise specified. Control patients (n = 35) received over-the-wire exchange of their tunneled dialysis catheter due to infection with any organism besides staphylococcus. Overall catheter survival and catheter survival among staphylococcal species were assessed. There was no difference in tunneled dialysis catheter survival between study and control groups (P = 0.46). Median survival time was 96 days for study catheters and 51 days for controls; survival curves were closely superimposed. There also was no difference among the three staphylococcal groups in terms of catheter survival (P = 0.31). The median time until catheter removal was 143 days for SE, 67 days for CNS, and 88 days for SA-infected catheters. There is no significant difference in tunneled dialysis catheter survival between over-the-wire exchange of staphylococcus-infected tunneled dialysis catheters and those infected with other organisms.
    CardioVascular and Interventional Radiology 05/2011; 34(6):1230-5. · 2.09 Impact Factor
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    ABSTRACT: Percutaneous transluminal angioplasty (PTA)-induced venous rupture is a common complication of hemodialysis access interventions. The authors sought to determine if venous rupture rates and management differed between grafts and fistulas, and in the fistula subset, between transposed and nontransposed fistulas. Patients experiencing venous rupture during hemodialysis PTA over a 5-year period were identified. Of 1,985 hemodialysis interventions, 75 ruptures occurred in 69 patients (46 women) with a mean age of 63 years (range, 31-88 y). Rupture rates, proportion of successful treatments, and treatment type and number (ie, balloon tamponade, stent, covered stent) were determined. Rupture was more common in fistulas overall (5.6%, 39 of 693) compared with grafts (2.8%, 36 of 1,292; P = .002), in transposed (10.7%, 20 of 187) compared with nontransposed fistulas (3.8%, 19 of 506; P = .001), and in transposed fistulas compared with grafts (P = .0001). There was no significant difference between nontransposed fistulas and grafts. Treatment success (ie, resolution of extravasation) was the same among groups: 69% (27 of 39) in fistulas overall, 70% (14 of 20) in transposed fistulas, 68% (13 of 19) in nontransposed fistulas, and 72% (26 of 36) in grafts. There was a greater need for stents in grafts (38.9%, 14 of 36) compared with fistulas (12.8%, five of 39; P = .003). PTA-induced rupture is more common in fistulas than grafts, and this effect seems nearly entirely driven by transposed fistulas. Although rupture treatment in fistulas of all types yielded similar success to grafts, and graft ruptures were more difficult to treat than fistula ruptures, the high rupture rates in transposed fistulas attest to the increased difficulty of treating this subset of fistulas.
    Journal of vascular and interventional radiology: JVIR 05/2009; 20(6):744-51. · 1.81 Impact Factor
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    ABSTRACT: To analyze the use of preoperative venographic mapping in patients who require permanent hemodialysis access. Ninety-one patients underwent 108 preoperative studies. Sixty-eight (75%) were documented to have ongoing or previous hemodialysis at the time of the study. A total of 154 arms were assessed with venograms (75 right, 79 left); 74 of the patients (81%) had previous access. Venographic mapping was not performed in patients with clearly usable veins as determined by the referring surgeon. A total of 170 veins were suitable for access creation (ie, continuous vein of suitable caliber). Of these, 78 were used (40 fistulas [51%] and 38 grafts [49%]), and 87% of accesses were successfully used for dialysis (73% primarily, 14% after additional intervention). Anatomic variants included early brachial-basilic confluence (44%), double terminal cephalic arch (4%), and brachial-basilic "ladders" (7%). Significant central venous stenosis was found in 10% of studies, limiting the ability to use the affected side for access. There were significant associations between (i) the number of previous accesses and access type created (P = .002, Fisher exact test) and (ii) the number of veins visualized and access type created (P < .001, Fisher exact test). A greater number of previous access attempts correlated with graft rather than fistula placement for permanent access, and increased numbers of veins seen on venography correlated with an increased chance of permanent access placement. Venography may identify clinically occult veins usable for hemodialysis access. Anatomic variants are common and may affect choice of access site.
    Journal of Vascular and Interventional Radiology 07/2008; 19(7):1027-33. · 2.00 Impact Factor
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    ABSTRACT: It is common practice to perform culture of the tip of a catheter when a previously indwelling vascular catheter is removed for presumed infection. This study was conducted to determine the effect of hemodialysis catheter tip cultures (CTCs) on patient management. Patients whose tunneled hemodialysis catheter (TDC) was removed for infection and who had a CTC between July 2001 and June 2006 were identified. The study sample included 242 patients with 330 catheters (109 men, 133 women). Patients' mean age was 58 years (range, 22-94 y). Catheter tip and blood culture (BC) results obtained during the event leading to catheter removal were recorded. Antimicrobial therapy before and after cultures was recorded. Medical records were reviewed for any indication that the treatment plan was influenced by tip culture results. Of 330 catheters, 134 had positive CTC findings; of these, complete records were available for 52 catheters. The treatment plan for patients with suspected catheter-related bloodstream infection (CRBSI) leading to TDC removal did not change in response to semiquantitative CTC results (51 of 52 patients; 98%). In a single case in which CTC results impacted management, this was because of a delay in processing BCs. Negative CTC findings (n = 108) never changed management (ie, resulted in cessation of antibiotic therapy). Seventy-three percent of patients (n = 38) received empiric antibiotics before any culture results. In these cases, the BC susceptibility profiles confirmed the appropriateness of the initial treatment (n = 10) or led to a change (n = 28). CTC did not alter management in the treatment of TDC infection. Because CTCs increase costs, their routine use should be abandoned in this population.
    Journal of Vascular and Interventional Radiology 11/2007; 18(10):1227-31. · 2.00 Impact Factor
  • Seminars in Dialysis 09/2007; 11(1):3 - 6. · 2.25 Impact Factor
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    ABSTRACT: To retrospectively evaluate the natural history of high-grade (>50%) asymptomatic central venous stenosis (CVS) in hemodialysis patients and the outcome of serial treatment of CVS with percutaneous transluminal angioplasty (PTA). The institutional review board granted exemption for this retrospective study, the need for informed consent was waived, and all data collection was in compliance with HIPAA. Patients with hemodialysis access requiring maintenance procedures between 1998 and 2004 and incidentally found to have ipsilateral (> or =50%) CVS were identified from a departmental database. Thirty-five patients (19 men, 16 women; mean age, 58.7 years) with 38 grafts met inclusion criteria, and 86 venograms were reviewed. CVS was measured by using venograms obtained before and after PTA, if performed. Patients with arm swelling, multiple CVS, indwelling catheters, and stents at the first encounter were excluded. CVS progression was calculated by dividing the change in the degree of stenosis by the time between venographic examinations. Wilcoxon rank sum test was used to evaluate differences in rate of CVS progression between treated and nontreated patients. Mean degree of CVS before intervention was 71% (range, 50%-100%). Sixty-two percent (53 of 86) of lesions had associated collateral vessels; 28% (24 of 86) of CVSs were not treated. Mean degree of stenosis in this group was 72% (range, 30%-100%); mean progression was -0.08 percentage point per day. No untreated CVS progressed to symptoms, stent placement, or additional CVS. Seventy-two percent (62 of 86) of CVSs were treated with PTA. Mean degree of stenosis in this group was 74% (range, 50%-100%) before and 40% (range, 0%-75%) after treatment; mean progression was 0.21 percentage point per day after treatment (P = .03). Six (8%) of 62 treatments were followed by CVS escalation; one patient developed arm swelling, four required stents, and four developed additional CVS. PTA of asymptomatic CVS greater than 50% in the setting of hemodialysis access maintenance procedures was associated with more rapid stenosis progression and escalation of lesions, compared with a nontreatment approach.
    Radiology 04/2006; 238(3):1051-6. · 6.34 Impact Factor