Anemia management with darbepoetin-alfa in outpatient hemodialysis patients switched from epoetin-alfa: a community hospital experience.

Epoetin-alfa (EA) and darbepoetin-alfa (DA) are agents for treating anemia in dialysis patients. In September 2005, our free-standing outpatient hemodialysis center (community-hospital based) implemented an interchange from EA to DA. Since then, all hemodialysis patients receive DA as the preferred agent. We performed this observational study to compare effectiveness of DA with EA in anemia management in a cohort of hemodialysis outpatients. We studied 98 hemodialysis outpatients who received twice to thrice weekly EA from January to August 2005. These patients were switched to DA in September 2005, and baseline DA dose was calculated from the conversion table in the package insert. After a 4 month titration phase, the same cohort of patients, now on once weekly DA, was followed from January to September 2006. Dose of EA or DA was adjusted to maintain hemoglobin at 11 to 13 g/dL. Hematologic and dialysis parameters were collected on a monthly basis, and inpatient data were excluded. Mean ± standard deviation age was 65.8 ± 14.2 years, with 42 (42.9%) women. Mean ± standard deviation hemoglobin level was 12.5 ± 1.6 g/dL during EA and 12.5 ± 1.6 g/dL during DA therapy (P = 0.23). Proportion of patients achieving hemoglobin (11-13 g/dL) was 44.5% ± 28.9% with EA and 49.8% ± 25.8% with DA (P = 0.09). Average intrapatient absolute hemoglobin variability was 1.0 ± 0.5 g/dL on EA and 1.1 ± 0.5 g/dL on DA (P = 0.29). Median (and interquartile range) EA dose used was 11,400 (7,050-22,800) IU/week, and median DA dose was 59.8 (40-91.6) mcg/week with an EA:DA dose conversion ratio of 191:1. Patients on EA or DA had similar dialysis adequacy, albumin, and iron parameters. DA is as effective as EA in treating anemia in hemodialysis outpatients. Dose requirement of DA is greater than 200:1 of the amount of EA and may not translate into cost savings.

Atypical chest pain: coronary, aortic, and pulmonary vasculature enhancement at biphasic single-injection 64-section CT angiography.

PURPOSE: To prospectively evaluate the enhancement of coronary, pulmonary, and thoracic aortic vasculature by using biphasic single-acquisition 64-section computed tomographic (CT) angiography and to prospectively evaluate if differences in right side of the heart and coronary venous enhancement interfere with interpretation of coronary arteries. MATERIALS AND METHODS: With internal review board approval and HIPAA compliance, 50 patients (16 men, 34 women; mean age, 51.5 years; range, 30-75 years) with atypical chest pain were referred from the emergency department and were imaged with a 64-section CT scanner after premedication with oral atenolol and/or intravenous metoprolol. Thoracic CT angiography with retrospective gating was subsequently performed with a single biphasic injection of 130 mL of iso-osmolar contrast material (100 mL at 5 mL/sec and 30 mL at 3 mL/sec) in caudal-to-cranial acquisition. Coronary, aortic, and pulmonary arterial attenuation values were obtained. Coronary venous and right atrial enhancement were evaluated to assess whether there was interference with coronary artery evaluation. A two-tailed Friedman test was used to evaluate differences among segments within each artery. RESULTS: Mean coronary arterial, pulmonary arterial, and aortic attenuation values were significantly higher than the 250-HU threshold (P < .05). Mean pooled coronary arterial (288.9 HU +/- 64.8), pulmonary arterial (316.4 HU +/- 79.9), and aortic (329.9 HU +/- 63.3) attenuation values were significantly higher than the 250-HU threshold (P < .0001). Coronary venous enhancement did not affect depiction or interpretation of coronary arteries. Right atrial streak artifact focally traversed the right coronary artery in only one study. CONCLUSION: The aforementioned thoracic CT angiographic protocol provides enhancement of coronary, aortic, and pulmonary vasculature in a single breath hold without interference from right side of the heart streak artifact or coronary venous enhancement.

Coronary 64-slice computed tomographic angiography models employing aortic root and selective catheter directed contrast enhancement in swine: technical feasibility and preliminary results using 3D and 4D reconstructions.

PURPOSE: The technical feasibility of combining catheter directed coronary enhancement and multidetector computed tomographic angiography (MD-CTA) is presented in a swine model at various cardiac and injection rates. MATERIALS/METHODS: A 64-slice CT scanner was used under animal IRB approval in four sedated swine. Common femoral venous/arterial access with a 5 Fr micropuncture kit was ultrasound guided. Investigational 5 Fr diffusion-tip pigtail [aortic root (AR)-MD-CTA] and conventional 5 Fr coronary [selective (S)-MD-CTA] catheters were positioned on the CT table with c-arm fluoroscopy. AR-MD-CTA commenced 1-2 s after injection of 50 cc Visipaque mixed with 50 cc NS at 6 cc/s (n=3), 8 cc/s (n=5) or 10 cc/s (n=7) (HR=120, 100, 90, 80 or 65 bpm). S-MD-CTA (right and left, n=4) (HR= 90, 80, or 65 bpm) commenced 1-2 s after injection of 5 cc Visipaque mixed with 5 cc NS (1 cc/s). IV-MD-CTA (n=4) (HR=80 bpm) commenced 5 or 10 s after aortic peak density with 100 cc Visipaque (5 cc/s) and 50 or 75 cc NS (5 cc/s) flush. Conventional angiography (n=2) used standard protocol. MD-CTA was performed with the following parameters: collimation 0.6 mm, tube rotation time 0.3 s, table feed/rotation 3.8 mm, scan time 10-12 s, tube voltage 120 kVp, effective mAs 850, pitch 0.2, FOV 109-123 mm, slice thickness/increment 0.6 mm/0.3 mm, kernel B25 f smooth. Ex vivo imaging (64-slice CT, n=3) was also performed. Post-processing consisted of coronary peak densities, 3D-MIP's and 4D projections. RESULTS: Catheter directed MD-CTA was feasible at all injection rates at and below 100 bpm and yielded higher peak coronary attenuation values than IV-enhanced studies. Definition and clarity of the tributary and distal anatomy was also higher than IV-enhanced CTA. CONCLUSIONS: Catheter directed MD-CTA can be performed by retrofitting the current CT scanner with a portable c-arm fluoroscopy unit. S and AR MD-CTA provide high coronary anatomy definition and luminal attenuation without obscuring cardiac chamber signal and with the least iodinated contrast volume.