Raphael M. Cohen

William Penn University, Filadelfia, Pennsylvania, United States

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Publications (12)59.69 Total impact

  • [Show abstract] [Hide abstract]
    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. DOI:10.1007/s00270-011-0180-4 · 2.07 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. DOI:10.1016/j.jvir.2009.03.013 · 2.41 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. DOI:10.1016/j.jvir.2008.03.015 · 2.41 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. DOI:10.1016/j.jvir.2007.06.031 · 2.41 Impact Factor
  • Michael R. Rudnick · Jeffrey S. Berns · Raphael M. Cohen
    Seminars in Dialysis 09/2007; 11(1):3 - 6. DOI:10.1111/j.1525-139X.1998.tb00197.x · 1.75 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. DOI:10.1148/radiol.2383050119 · 6.87 Impact Factor
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    ABSTRACT: Hypertension is a recognized complication of partial correction of anemia with recombinant human erythropoietin (epoetin) in hemodialysis patients. We used interdialytic ambulatory blood pressure (ABP) monitoring to study the effects of partially corrected anemia versus normal hematocrit (hct) on BP in hemodialysis patients. Repeated interdialytic ABP monitoring was performed for up to one year in 28 chronic hemodialysis patients with cardiac disease who were randomized to achieve and maintain normal hct levels (42 +/- 3%, group A) or anemic hct levels (30 +/- 3%, group B) with epoetin. Routine BP measurements obtained at dialysis treatments were also evaluated. Mean hct levels were 30.7 +/- 0.7% in group A and 30.6 +/- 0.7% in group B at baseline, then 39.3 +/- 1.2% (group A) and 33.5 +/- 0.6% (group B) at four months, and 42.0 +/- 1.1% (group A) and 30.4 +/- 1.0% (group B) at 12 months. Baseline ABP and routine dialysis unit BP levels were not different between the groups. At 2, 4, 8, and 12 months of follow-up, there were no statistically significant differences in any BP parameters between groups or increases in any BP parameters in either group A or group B patients compared with baseline. At 12 months, the mean nighttime diastolic BP (DBP) in group A patients was slightly but significantly lower than the mean daytime DBP (daytime DBP 76.6 +/- 1.9 mm Hg vs. nighttime DBP 72.9 +/- 2.1 mm Hg, P < 0.05). The mean daytime and nighttime BPs were not different from each other at two, four, and eight months in group A or at any time in group B, and in both groups, most patients had little diurnal change in BP. Correction of hct to normal with epoetin in chronic hemodialysis patients with cardiac disease did not cause increased BP as assessed by interdialytic ABP monitoring or by the measurement of routine predialysis and postdialysis BP. There was little diurnal change in systolic or diastolic BP at baseline or after correction of anemia to normal levels, and although mean nighttime DBP was lower than mean daytime DBP at 12 months in group A, the maintenance of normal hct levels did not affect the abnormal diurnal BP pattern seen at moderately anemic hct levels in most patients.
    Kidney International 07/1999; 56(1):253-60. DOI:10.1046/j.1523-1755.1999.00531.x · 8.56 Impact Factor
  • Jeffrey S. Berns · Raphael M. Cohen · Michael Silverman · John Turner
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    ABSTRACT: Two patients with oliguric acute renal failure (ARF) attributed to crystalluria and nephrolithiasis with obstructive uropathy caused by the human immunodeficiency virus protease inhibitor indinavir are described. In both patients, ARF resolved with administration of intravenous fluids. One patient required urologic intervention to relieve bilateral ureteral obstruction.
    American Journal of Kidney Diseases 11/1997; 30(4):558-60. DOI:10.1016/S0272-6386(97)90316-4 · 5.90 Impact Factor
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    ABSTRACT: To compare the pharmacokinetics of bromfenac among normal subjects and renally compromised patients and patients with end-stage renal disease. Bromfenac pharmacokinetics were examined after a single 50 mg oral dose in 18 subjects with normal kidney function, 12 subjects with decreased kidney function, and 10 dialysis-dependent subjects. Protein binding was assessed by equilibrium dialysis. Mean peak concentrations and areas under the concentration versus time curve ranged from 3.3 to 3.9 micrograms/ml and 5.1 to 6.9 micrograms.hr/ml, respectively. The mean unbound fraction in the subjects receiving dialysis (0.29%) was nearly twice that in the subjects with normal kidney function (0.17%) and in the subjects with impaired kidney function (0.16%), but no differences were detected in clearance, volume of distribution, or their free fraction-corrected counterparts. Bromfenac half-life nearly doubled in the impaired and dialysis groups but was shorter than the anticipated 8-hour dose interval. Eight subjects had a total of 11 study events; none were serious and all were self-limited. These findings suggest that no dosage adjustment is necessary in patients with impaired kidney function, but clinical monitoring appropriate for their individual condition is recommended.
    Clinical Pharmacology &#38 Therapeutics 04/1997; 61(3):312-8. DOI:10.1016/S0009-9236(97)90163-6 · 7.90 Impact Factor
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    ABSTRACT: Contrast media-associated nephrotoxicity (CM-AN) continues to be a common cause of hospital-acquired acute renal failure. This review of CM-AN discusses the pathogenesis, clinical features, incidence, risk factors with an emphasis on pre-existing renal insufficiency and diabetes mellitus, volume of contrast media, low osmolar versus high osmolar contrast media, and prophylaxis. Although the literature contains an abundance of information concerning CM-AN, areas of uncertainty remain in respect to clinical significance, risk with modem day radiological techniques and contrast media, optimal prophylactic regimens, and criteria for creatinine screening before contrast media administration.
    Seminars in Nephrology 02/1997; 17(1):15-26. DOI:10.1097/00041552-199603000-00005 · 3.48 Impact Factor
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    ABSTRACT: We report a chronic hemodialysis patient with severe hyperparathyroidism who developed hypoglycemia with inappropriate hyperinsulinemia following parathyroidectomy. An abrupt fall in parathyroid hormone level and administration of large amounts of calcitriol may have resulted in increased insulin release and enhanced tissue sensitivity to insulin producing sustained hypoglycemia in this patient.
    Nephron 02/1992; 60(1):100-3. DOI:10.1159/000186712 · 13.26 Impact Factor
  • Jeffrey S. Berns · Raphael M. Cohen · Michael R. Rudnick
    American Journal of Nephrology 02/1991; 11(1):73. DOI:10.1159/000168277 · 2.67 Impact Factor

Publication Stats

261 Citations
59.69 Total Impact Points


  • 2006–2011
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 2007
    • Hospital of the University of Pennsylvania
      • Department of Medicine
      Philadelphia, Pennsylvania, United States
  • 1992
    • Philadelphia ZOO
      Filadelfia, Pennsylvania, United States