Red blood cell survival in long-term dialysis patients.

BACKGROUND: Shortening of red blood cell (RBC) survival contributes to the anemia of chronic kidney disease. The toxic uremic environment accounts for the decreased RBC life span. The contribution of mechanical damage caused by hemodialysis to the shortened life span is unclear. Reductions up to 70% in RBC survival have been reported in uremic patients. To date, no accurate well-controlled RBC survival data exist in dialysis patients treated using different dialysis modalities and receiving erythropoiesis-stimulating agent (ESA) therapy. The aim of this study was to determine RBC survival in hemodialysis (HD) and peritoneal dialysis (PD) patients compared with healthy persons. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: 14 HD patients and 5 PD patients were recruited from the dialysis unit. Healthy volunteers (n = 14) age- and sex-matched to HD participants were included. All dialysis patients received either ESA therapy or regular iron supplementation. PREDICTOR: Dialysis patients versus age- and sex-matched healthy controls. OUTCOMES: RBC survival. MEASUREMENTS: RBC survival was determined using radioactive chromium labeling. RESULTS: More than 85% of dialysis patients were anemic (hemoglobin, 12.0 ± 1.1 g/dL); hemoglobin concentrations were not significantly different between HD and PD patients. Median RBC survival was significantly decreased by 20% in HD patients compared with healthy controls: 58.1 (25th-75th percentile, 54.6-71.2) versus 72.9 (25th-75th percentile, 63.4-87.8) days (P = 0.02). No difference was shown between the PD and HD groups: 55.3 (25th-75th percentile, 49.0-60.2) versus 58.1 (25th-75th percentile, 54.6-71.2) days (P = 0.2). LIMITATIONS: Label loss from RBCs associated with the chromium 51 labeling technique needs to be accounted for in the interpretation of RBC survival data. CONCLUSIONS: Despite current ESA therapy, decreased RBC survival contributes to chronic kidney disease-related anemia, although the reduction is less than previously reported. There does not appear to be net mechanical damage associated with HD therapy resulting in decreased RBC life span.

What arteries are detectable in the precarinal space on contrast-enhanced CT?

Although the precarinal space is critical in the interpretation of computed tomography (CT) of the thorax, vascular structures within the space have not been well documented. The aim of this study was to investigate vascular structures in the precarinal space that are detectable with contrast-enhanced CT scans. Contrast-enhanced CT chest scans from 90 patients aged 17-78 years (41 male, 49 female) were analyzed retrospectively. Twenty-two cadavers aged 54-93 years (13 male, 9 female) were used for gross anatomic study. We found that 9 of 90 cases of the contrast-enhanced CT scans had vessel-like structures detectable in the precarinal space, located primarily anterior to the right main bronchus. Single or double arteries were identified in the precarinal space of 19 cadavers. Thirteen of the 23 arteries observed were the right bronchial artery and 10 were the left bronchial artery. In two cadavers, a single right bronchial artery (2.5 and 4.0 mm in diameter), which could have been detected with contrast-enhanced CT, originated from the aortic arch and the root of the left subclavian artery and coursed in the precarinal space. Based on the variation in the location and size of the bronchial arteries observed in this study, we suggest that vascular structures are detectable in the precarinal space with contrast-enhanced CT, particularly anterior to the right main bronchus.