54 research outputs found
Equivalence of information from single versus multiple frequency bioimpedance vector analysis in hemodialysis
No full textKidney Int. 2005 Jan;67(1):301-13.
Equivalence of information from single versus multiple frequency bioimpedance vector analysis in hemodialysis.
Piccoli A, Pastori G, Guizzo M, Rebeschini M, Naso A, Cascone C.
Source
Department Scienze Mediche e Chirurgiche, University of Padova, Padova, Italy. [email protected]
Abstract
BACKGROUND:
In suspended cells, low-frequency current only passes through extracellular fluids, while current at higher frequencies passes through extra- and intracellular fluids. Cells in soft tissues are in contact with each other, which causes tissue anisotropy, meaning that impedance changes along different cell directions, with part of low-frequency current also passing through cells. Hence, equivalent information on body impedance change is expected at all frequencies, which we proved in a dynamic condition of fluid removal with hemodialysis.
METHODS:
We performed whole-body impedance spectroscopy (496 frequencies from 4 to 1024 kHz, SEAC SFB3 analyzer; Brisbane, Australia) before and during fluid removal (0, 60, 120, 180 min, 2.5 kg) in 67 hemodialysis patients. With increasing current frequency, resistance (R) decreases and reactance (Xc) moves along the Cole's semicircle on the R-Xc plane.
RESULTS:
The Cole's semicircles progressively enlarged and moved to the right on the R-Xc plane following fluid removal (increase in both R and Xc values at any given frequency). Xc values at 5 kHz (expected values close to 0 Ohm) were 70% of the maximun Xc, indicating an intracellular current flows at low frequencies. The correlation coefficient between R at 50 kHz (standard frequency) and R at other frequencies ranged from 0.96 to 0.99, and the correlation coefficient between Xc at 50 kHz and Xc at other frequencies at any time point ranged from 0.65 to 0.99.
CONCLUSION:
From high Xc values at low frequency, tissue anisotropy is inferred. Intra- and extracellular current flow causes equivalence of information based on functions of R and Xc measurements made at 50 kHz versus other frequencies
Soluble transferrin receptors and reticulocyte hemoglobin concentration in the assessment of iron deficiency in hemodialysis patients
No full textBackground: Diagnosing iron deficiency in hemodialysis (HD) patients is crucial for correct anemia management. Hypochromic erythrocytes appear to be the best available marker, but they are often unavailable. Transferrin saturation (TSAT) and ferritin are also indicated as reference markers by guidelines. We evaluated the usefulness of soluble transferrin receptor (s-TfR) and reticulocyte hemoglobin concentration (CHr), which have been recently proposed as more sensitive functional iron deficiency indicators. Methods: A single-center unselected cohort of 39 chronic HD patients underwent a cross-sectional determination of hemoglobin (Hb), hematocrit (Hct), CHr, transferrin, iron, TSAT, ferritin, folate, vitamin B12 and s-TfR. Twenty-nine patients (74.4%) were treated with subcutaneous erythropoietin (EPO) at a dose of 122 ± 98 U/kg/week and 24 patients (61.5%) were treated with intravenous (i.v.) iron gluconate, 62.5 mg/week. Results: Hb was 11.1 ± 1.2 g/dL, Hct 34.4 ± 3.7%, CHr 32.7 ± 3.8 pg, transferrin 170 ± 31 mg/dL, iron 60.2 ± 25.9 mg/dL, TSAT 30 ± 18%; ferritin 204 ± 219 ng/mL, folate 4.2 ± 1.0 mcg/L, vitamin B12 0.58 ± 0.15 mcg/L, and s-TfR 1.94 ± 0.83 mg/L. Both TSAT and s-TfR significantly correlated with CHr, but no relationship could be found between s-TfR and TSAT or between s-TfR and ferritin. Dividing the population into two groups based on iron repletion (ferritin >100 ng/mL, and TSAT >20%) we found no differences for CHr levels and significantly lower levels of s-TfR in the replete group (s-TfR 1.71 ± 0.70 vs. 2.29 ± 0.90 mg/L; p=0.033). Analysis of 2×2 tables demonstrated that 44% of patients with TSAT >20% had elevated (>1.5 mg/L) s-TfR, indicating a possible functional iron deficiency, but covariance analysis showed that TSAT had a better correlation to CHr. Conclusions: No clear-cut advantages in the use of CHr content and s-TfR levels as single diagnostic tests could be demonstrated by this cross-sectional study. However, our results suggest that the combined use of TSAT 1.5 mg/L (therefore, including all patients with low TSAT, but also patients with high s-TfR despite normal TSAT) could improve functional iron deficiency detection in dialysis patients suspected of having inflammatory conditions
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No full textValutazione dell’efficacia delle fibre vegetali (Glucoman) nel trattamento dell’obesità infantile
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Effect of hemodialysis on the metabolic clearance of 5-Fluorouracil in a patient with end-stage renal failure. Ther Drug Monit. 2005 Dec;27(6):816-8.
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EFFETTO DELL’EMOFILTRAZIONE CON RIGENERAZIONE ON-LINE DELL’ULTRAFILTRATO (HFR) SULLO STRESS OSSIDATIVO NEL PAZIENTE IN DIALISI CRONICA
No full textEffect of haemodiafiltration with online regeneration of ultrafiltrate on oxidative stress in dialysis patients.
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