Biomedical subjects

A Viernes

Publications and source records attributed to A Viernes.

6 recordsLinked to original sources

PubMed1994

Rapid red cell transfusion by apheresis.

Packed red cells (RBC) are customarily infused slowly to allow time for re-equilibration of intravascular volume, but they may be given rapidly for convenience during hemodialysis or partial RBC exchange when blood volume can be adjusted extracorporeally. We describe an apheresis procedure for rapid transfusion of RBC to patients with chronic anemia in which an equivalent volume of recipient plasma is withdrawn as donor RBC are infused. Fifteen such procedures, transfusing 3 to 5 RBC units each, have been performed on nine patients (4 of them outpatients) with either COBE Spectra or COBE 2997. Mean +/- SD procedure duration was 1.79 +/- .44 hr; patient hemoglobin rose from 7.3 +/- 1.5 to 12.0 +/- 1.5 g/dl. Comparison to conventional transfusion was possible for nine procedures on six patients in which rapid transfusion required .52 +/- .12 vs. 2.70 +/- .37 hr per unit (P < .001) and raised hemoglobin by 1.22 +/- .30 vs .88 +/- .34 g/dl per unit (P < .02). Pink plasma noted during one procedure was attributable to infusion of an older AS-1 unit with extensive storage hemolysis. Rapid transfusion was subjectively well tolerated. Immediate post-procedure systolic blood pressures did not differ significantly from baseline, although one hypertensive patient had headache followed by increased blood pressure 4 hours after a procedure. We conclude that rapid transfusion of RBC is a technically feasible and more time efficient means for RBC transfusion. It is particularly attractive in the outpatient setting, and could also prevent fluid overload associated with RBC transfusion in some volume-sensitive patients.

Adult↗

PubMed1991

Plateletpheresis with the COBE spectra single needle access option.

A group of modifications, including a reservoir bag in the return circuit, has been devised to allow single needle plateletpheresis with the COBE Spectra. We compared the number and quality of platelets collected from 10 subjects in paired donations with single and dual needle protocols. There was no evidence of hemolysis with either protocol. Mean (+/- SD) platelet yields were 3.61 +/- 1.47 x 10(11) with two needles and 3.31 +/- 1.31 x 10(11) with the single needle procedure (P = .13). Mean leukocyte levels (standard manual counting chamber) were 1.0 +/- 1.7 x 10(7) and 1.2 +/- 1.0 x 10(7), respectively (p = .78). pH values during storage were acceptable in both groups of concentrates, and there were no significant differences between the single needle and dual needle concentrates in morphology scores or beta-thromboglobulin levels at 0, 1, 3, or 5 days of storage. Thus the single needle modification produced platelets that were comparable in quantity and quality to those from the standard dual needle plateletpheresis protocol.

Blood Donors↗

PubMed1990

Computerization of plateletpheresis quality control records with a commercially available spreadsheet program.

Many apheresis units lack the resources to acquire customized computer software for record keeping. We have adapted a commercially available "spreadsheet" program (Lotus 1-2-3) to aid in quality control activities for plateletpheresis. Data are entered in a grid pattern wherein each donation occupies one row and successive columns contain numerical data derived from the donation. The last two columns contain formulas that calculate yield and collection efficiency from values entered in preceding columns. The program runs on an IBM PC or equivalent with 512 K RAM; the combined cost of a computer and software is currently under $2,000.00. Data entry requires fewer keystrokes per record than computation of yield and efficiency with a calculator, and creates an inclusive permanent record for future analysis. Data sorting and statistical functions allow rapid identification of incomplete records, and derivation of average platelet yield and/or collection efficiency for any time period of interest. The program also facilitates determining the proportion of donations that fall below any chosen cutoff. Performance characteristics of a particular instrument or operator can be assessed easily by isolating the pertinent records and analyzing them separately. The system will thus accomplish a variety of quality control activities, including those mandated by licensing agencies. It can be implemented by apheresis personnel with limited "computer literacy" and is superior to manual tabulation of quality control data in both ease of data entry and facility of analysis.

Data Interpretation, Statistical↗

PubMed1984

Analysis of serum free light chains by crossed immunoelectrophoresis: comparison with urinary light chains in light chain disease.

We investigated the relationship between serum free light chain levels measured by crossed immunoelectrophoresis in ten patients with light chain disease and traditional 24-hour urinary light chains in the same patients. The crossed immunoelectrophoresis test requires only a venipuncture for specimen acquisition, can be completed within 24 hours, and has a reproducibility (+/- 14%) comparable with that of other immunoprecipitin techniques. Twenty-eight serum-urine pairs, representing 18 discrete intervals, were analyzed. There was a close relationship between changes in serum and urine light chain levels, with a correlation coefficient of .77 or .93, depending on the method of calculation. This suggests that serum light chain levels measured by crossed immunoelectrophoresis would be equivalent to urinary light chain levels as indicators of tumor burden. Monitoring serum levels would have the advantage of greatly simplified specimen acquisition. In patients with renal failure, serum light chain levels should be a superior indicator of light chain synthesis.

Blood Protein Electrophoresis↗

PubMed1983

Complement metabolism during membrane plasma separation.

Because it has been found that some plasma separator membranes can activate complement in serum, this study focuses on the behavior of complement during actual membrane plasmapheresis. Complement metabolism in subjects undergoing membrane plasma separation with three different prototypic devices was studied. Complement activation was judged by crossed immunoelectrophoretic analysis of C3 in plasma. A cellulose acetate separator employed with heparin as the anticoagulant caused extensive C3 conversion (up to 50%) in separated plasma. A polysulfone separator used with citrate, and a polyvinylchloride derivative separator employed with heparin plus citrate, caused only small amounts of C3 conversion (0-10%) in separated plasma. C3 conversion in the cellulose acetate separator was reduced when citrate was included in the anticoagulant regimen, whereas C3 conversion in the polyvinylchloride derivative separator was increased when citrate was omitted. Activation of complement by the membrane material may occur during membrane plasma separation. Selection of membranes judged weakly activating by in vitro screening and the use of citrate anticoagulation would appear to minimize complement activation in membrane plasma separators.

Cellulose↗

PubMedDate not supplied

Complement activation by plasma separator membranes.

Because of their structural similarity to dialysis membranes, six plasma separator membranes were evaluated for the ability to activate complement, as judged by immunoconversion of the third component of complement in crossed immunoelectrophoresis. A polysulfone and two cellulose acetate membranes were relatively strong alternative pathway activators. Polypropylene, poly[vinylidine fluoride] and polyvinyl-chloride derivative membranes were weak activators in some sera. Membrane activation was inhibited in citrate-anticoagulated but not in heparin-anticoagulated plasma. The results of such in vitro screening should be of value in selecting materials and anticoagulation regimens for membrane plasma separators.

Complement Activation↗