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V Kretschmer

Publications and source records attributed to V Kretschmer.

At least 91 records · Page 5Linked to original sources
PubMed1993

[Preliminary results of the 2nd multicenter study. Thrombocytapheresis with the Fresenius AS-104 blood cell separator and ring study of cell counting. Section of Therapeutic and Preparative Hemapheresis of the DGTI].

Only multicenter studies on cell separators give valid data to compare different cell separators. The aim of the 2nd multicenter study was to evaluate the separation protocol, software version V 4.61, of the Fresenius AS-104 cell separator for efficiency and deviation from predicted yields. Plateletpheresis data from twelve hemapheresis centers, using identical apheresis protocols and cell counting methods, were registered and statistically analyzed. Additionally, the counting methods of the centers were controlled by a ring study with biweekly external cell count trials. To get a comparison, the apheresis data, which depend on the center effects, were corrected by the values from the ring study. Preliminary results of 380 runs are 45.2 +/- 8.1% for the separation effectivity, 1.95% deviation from the predicted yield, whereby 90% of all runs deviated less than 20% from the predicted yield. 50% of products had a WBC contamination below 6 x 10(6).

Blood Volume↗
PubMed1993

German multicenter studies on plateletpheresis from healthy donors. German Hemapheresis Study Group.

It is reported on two German Multicenter Plateletpheresis Studies with the Fresenius AS 104 cell separator accompanied by a Multicenter Counting Study. 15 centers participated, a total of 1884 separations were evaluated. It could be shown that multicenter studies help to give a more objective opinion about a cell separator and the separation protocol used if it is possible to improve the counting methods and to eliminate individual center effects by an accompanying Multicenter Counting Study. The AS 104 proved to be a good cell separator for platelet collection regarding platelet yields (3.1 x 11" from 3.5 I citrated blood), separation efficiency (about 45%), yield prediction (SD = not equal to 15%) and leukocyte contamination (median WBC 47 x 10(6)).

Blood Donors↗
PubMed1992

Teflon bags for 5-day storage of platelet concentrates (PC) from cell separator.

There exist no data yet about platelet storage in teflon bags. Therefore, a paired study has been performed to evaluate their suitability for the 5 days storage of platelet concentrates (PC) from the cell separator Fresenius AS-104. The PC's of the AS-104 were stored in teflon as well as in polyolefin bags each (PL-732). In addition, PC's of the Baxter CS-3000 were stored in PL-732. PH, cell counts, platelet morphology, aggregation, adherence and ADP/ATP concentration, plasma beta TG, glucose, lactate and thrombin-antithrombin III complexes were investigated at day 0, 3 and 5 of storage. The results show that the teflon bags are quite suitable for 5 day storage of the PC's. But the functional superiority of fresh PC's from the AS-104 seemed to be reduced by storage in teflon bags compared to storage in PL-732. The unfavorable size and geometry of the teflon bags used could have been the cause. Therefore, size and geometry were consequently changed in the meantime.

Blood Preservation↗
PubMed1992

New polyolefin foil for 5-day storage of platelet concentrates (PC) collected by apheresis.

In a paired study 12 platelet concentrates (PC) of Fresenius AS-104 cell separator were stored in new polyolefin bags of Fresenius (LE2) and Fenwal PL-732 bags. On day 0 and after 3 and 5 days of storage pH, pO2, pCO2, cell counts, platelet morphology and aggregability, plasma glucose, lactate, LDH and beta TG were determined. The overall changes fell within the expected range. No relevant differences between the two bags could be detected, although a few parameters (pH, pCO2) are slightly but statistically/significantly different. It can be concluded that the new polyolefin bag is well suited for 5-day storage of PC's from the AS-104.

Blood Preservation↗
PubMed1992

Filtration of buffy coat free red cell concentrates in additive solution.

Leukocyte poor RCC's (LP-RCC) are indicated in chronically transfused patients in order to prevent non-hemolytic transfusion reactions and HLA alloimmunization. In this study buffy coat free red cell concentrates (BCF-RCC) in additive solution (SAG-M) stored for four weeks were leukocyte depleted by filtration with three different filter systems (Erypur Optima (E), Sepacell R500 B (S) and, Pall RC, 50 TM (P)). The BCF-RCC's were prepared using 'bottom and top (BAT)' systems and automatic separation containing about 20% leukocytes and 5% platelets of fresh whole blood. The leukocyte concentration could be reduced to less than 5 x 10(6) per RCC with all filter systems equally: Leukocytes/RCC's: E .58 +/- .94, S .36 +/- .55, P .55 +/- .69 x 10(6). The leukocyte depletion was even in case of filtering two RCC's through one filter (double filtration) efficient enough in order to keep leukocyte contamination below the 'critical immunogenic load for leukocytes (CILL)'. But significant differences concerning the damage of red cells (free hemoglobin, LDH, HBDH) were measured which were even considerable: free hemoglobin E = 3.69 +/- 2.28, S = 1.31 +/- 1.24, P = 3.58 +/- 2.34 g/l. Double filtration was only performed with filter system S showing the best blood compatibility. But the second BCF-RCC also showed considerable hemolysis. Therefore, double filtration of RCC's only seems to be indicated under optimal conditions with blood compatible filters for selected patients. Bed side filtration cannot be recommended because of the risk of hemolysis that makes quality control necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Component Removal↗
PubMed1992

Superiority of gel centrifugation in antibody screening and identification.

We report on the direct comparison of gel centrifugation technique and tube testing for antibody screening (ABS) under controlled routine conditions. 3,000 blood samples were screened for antibodies (AB) by gel centrifugation (ID-System, bromelin 37 degrees C and room temperature, indirect antiglobulin test with LISS) and a sensitive tube test (TT; bromelin two-phase test, 37 degrees C and room temperature, and indirect antiglobulin test with 22% bovine albumin) in parallel. By ID significantly more relevant and potentially hemolytic AB (51 vs. 35 AB/1.7 vs. 1.2%) could be detected: anti-E 4, -C 1, -D 4, -CW 2, -c 2, -Jk(a) 2, -Jk(b) 1. Eleven of these even remained negative in TT when retested with increased sensitivity and taking additional (homozygous) test cells. In addition, naturally occurring but rarely hemolytic AB (35 vs. 23 AB/1.2 vs. 0.8%) were more frequently detectable by ID: anti-Le(a) 6, -Le(b) 2, -P1 6. In contrast, only two AB were only positive in TT: anti-Le(a) 1, -Le(a, b) 1. The main disadvantage of the ID was its frequent positivity (7.7 vs. 4.3%) due to irrelevant cold AB (anti-I, -HI, -H) and unspecific factors. This can be partly reduced by omission of the bromelin test at room temperature (ID 3.0%, TT 1.5%) as the detection of relevant AB is not affected. The frequency of naturally occurring AB was still the same as in TT (0.7%) when bromelin at room temperature was omitted in both techniques. Further advantages of the ID are simplicity, small volumes of sera and reagents, and easy evaluation.

Blood Grouping and Crossmatching↗
PubMed1992

Improvement of the separation of blood by modification of separators Optipress and Biotrans Separator.

UNLABELLED: By use of the new top-and-bottom bag system and automatic separators the quality of red cell concentrates (RCC) and fresh frozen plasma (FFP) could be markedly improved. Simultaneous preparation of storable single-donor platelet concentrates (PC) resulted, however, in too high losses of red cells and plasma. Through modification of the pressure plate of the separators and variation of the residual buffy coat (BC) volumes we tried to optimize the separation in this respect. In a second study we tried to establish the preparation of platelet-rich plasma (PRP) using top-and-bottom bag systems and automatic separators. MATERIALS AND METHODS: 1st study: 149 whole-blood units (Biopack U, quadruple systems) were separated into components either with Optipress (Opt, n = 58) or with Biotrans Separator (Bio, n = 91). To Optipress additional plates, 3-6 mm thick, were attached and the residual BC volume was varied by different adjustments of the distance screw. The Biotrans Separator was used with a plane pressure plate as well as with a modified plate having a transverse groove; the residual BC volume was adjusted to 50-120 ml. 2nd study: 15 whole-blood units were separated into PRP and RCC either using the Optipress (standard version, n = 5) or the Biotrans Separator (alternating opening of clamps, standard plate, n = 10). RESULTS AND CONCLUSIONS: 1st study: Both separations could be improved. The loss of red cells was significantly lower in case of the Biotrans Separator: Bio 15.6%, Opt 25.9%, p < 0.001. Other separation parameters showed no relevant difference between both separators. 2nd study: By use of the Biotrans Separator significantly less platelets could be separated (Bio 75.1 x 10(9), Opt 87.0 x 10(9), p < 0.05), but the PRP clearly was contaminated with less leukocytes (Bio 51.0 x 10(6), Opt 458.9 x 10(6), p < 0.01). The contamination of the RCC with leukocytes (about 20%) was markedly improved in both methods when compared with conventional preparations. The mean loss of red cells was 12.8% in both methods.

Blood Component Removal↗
PubMed1992

[Filtration of buffy coat-free erythrocyte suspensions in additive solution].

Buffy coat-free red cell concentrates in SAG-M (RCC) were produced by BAT system (leukocyte content 132 x 10(6)/RCC). They were stored for 4 weeks and filtered by Erypur Optima (E), Sepacell R 500 B (S) und PALL RC 50 TM (P). Leukocyte depletion was very effective (E: 0.56 x 10(6)/RCC; S: 0.36 x 10(6)/RCC; P: 0.55 x 10(6)/RCC) but hemolysis was remarkable (E: 301 +/- 195; S: 127 +/- 123; P: 368 +/- 256 mg/RCC). Therefore preparation of two RCC per filter was only acceptable with S. In S and P loss of red cells was tolerable (E: 90.5; S. 41.8; P: 38.2). In contrast, E should be rinsed with sodium chloride at the end of the preparation. In E and S filtration times were short without additional pressure (E: 6.6 min; S: 4.7 min; P: 20.3 min). We conclude from our results that the use of buffy coat-free red cell concentrates in additive solution considerably reduces the problems of filtration, e.g. storage interval, leukocyte reduction, hemolysis, filtration flow. Despite this, bedside filtration is not recommended because quality assurance is necessary.

Blood Component Transfusion↗
PubMed1992

[Production of rejuvenated and stable, leukocyte depleted erythrocyte concentrates using the heated centrifugation method].

We report on an alternative to filtration for the preparation of leukocyte-poor red cell concentrates (LP-RCC). It is based on the method of Schneider. Using RCC with buffy coat it is comparably effective in leukocyte reduction [98.3 +/- 1.0%, (3.7 +/- 2.6) x 10(6) leukocytes] and more effective in platelet reduction (96.9 +/- 2.5%). Addition of PAGGS-M before heating (30 min, 37 degrees C) as well as after preparation significantly reduces hemolysis (free hemoglobin, LDH, HBDH) and improves the quality of the LP-RCC (ATP, 2,3-DPG) during storage for 24 h after preparation. LP-RCCs prepared with PAGGS-M after 6-day storage show still better quality than before preparation and about the same quality as LP-RCCs 24 h after conventional preparation with saline solution. In conclusion, by use of PAGGS-M and sterile docking LP-RCCs of adequate quality for 6-day storage can be prepared, improving the supply of the patients concerned.

Adenine↗
PubMed1992

[Superiority of the gel centrifugation method (ID System) in detection of erythrocyte antibodies].

We report on the direct comparison of gel centrifugation technique and tube testing for antibody (AB) screening (ABS) under controlled routine conditions. 3,000 blood samples were screened for AB by gel centrifugation (ID-System, bromelin 37 degrees C and room temperature, indirect antiglobulin test with LISS) and a sensitive tube test (T; bromelin two-phase test 37 degrees C/room temperature and indirect antiglobulin test with 22% bovine albumin) in parallel. By ID significantly more relevant and potentially hemolytic AB (51 vs. 35 AB/1.7 vs. 1.2%) could be detected: anti-E 4, anti-C 1, anti-D 4, anti-CW 2, anti-C 2, anti-Jk (a) 2, anti-Jk (b) 1. 11 of these even remained negative in tube test when retested with increased sensitivity and taking additional (homozygous) test cells. In addition, naturally occurring but rarely hemolytic AB (35 vs. 23 AB/1.2 vs. 0.8%) were also more frequently detectable by ID: anti-Le (a) 6, anti-Le (b) 2, anti-P1 6. In contrast, only two AB were only positive in T: anti-Le (a) 1, anti-Le (ab) 1. The main disadvantage of ID was its frequent positivity (7.7 vs. 4.3%) due to irrelevant cold AB (anti-I, anti-HI, anti-H) and unspecific factors. This can be partly reduced by omission of the bromelin test at room temperature (ID 3.0%, T 1.5%) as the detection of relevant AB is not affected. The frequency of naturally occurring AB was still the same as in T (0.7%) when bromelin at room temperature was omitted in both techniques. Further advantages of ID are simplicity, small volumes of sera and reagents and easy evaluability.

Blood Group Antigens↗
PubMed1991

Comparison of different plateletpheresis systems.

Important criteria for assessing a cell separator are thrombocyte yield, separation efficiency, and purity of the thrombocyte concentrates. Based on a Multicentric Counting Study, in which 12 centers participated, we conclude that it is very difficult to compare the results of the various centers in regard to the separation efficiency. This is especially true for the comparison of different separation procedures. In Marburg we compared three different cell separators of the newest generation: COBE Spectra (n = 71), Fresenius AS-104 (n greater than 1100) and Fenwal CS-3000 TNX (n = 79). The COBE Spectra exhibited the best separation efficiency with the lowest leukocyte contamination (thrombocytes 4.3 x 10(11) (72.2%), leukocytes 0.5 x 10(7)) on the condition that the ACD-blood ratio did not differ more than -15% from the required algorithm. In order to reduce the risk to the donor, the system correspondingly reduces the donor's blood flow, resulting in a longer donation time (on the average 89-100 min). When the ACD ratio was reduced further, a considerable number of spontaneous and sometimes irreversible platelet aggregation occurred, increasing the risk of shortened survival through reduced platelet function. The AS-104 and the modified CS-3000 (TNX) had similar separation efficiencies (approx. 60%). While the platelet concentrates (PC) of the AS-104 almost reached the purity of that from the COBE Spectra, the leukocyte contamination of the CS-3000 PC's was still about four times as high. Other results published show that morphology, in-vitro function and in-vivo survival of thrombocytes collected with the AS-104 are significantly better than those from the CS-3000.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Banks↗
PubMed1991

Transfusion results of platelet concentrates using different cell separators.

115 patients with bone marrow aplasia/hypoplasia received a total of 567 transfusions of fresh HLA-selected platelet concentrates at random from the AS-104 and CS-3000 and, whenever possible, from both separators using the same donor. By daily platelet counting pre and up to seven days post transfusion, the posttransfusional increments per 10(11) platelets transfused were calculated. Fresh platelets collected from the AS-104 showed comparable in vivo recovery at the first day post transfusion but significant better survival compared to those from the CS-3000. This is in line with in vitro studies published before, where we already reported on better in vitro function and morphology. Increased platelet yields and improval of the platelet survival of the PC's from the AS-104 should result in prolonged transfusion intervals. When additionally evaluating a limited number of PC's from the AS-104 stored in teflon bags up to five days before transfusion (n = 12), we did not get favorable results compared to PC's from the CS-3000 stored in polyolefine bags. As this seemed to be due to the geometry of the bags, it was consequently changed in the meantime.

Anemia, Aplastic↗
PubMed1991

[Comparison of plateletpheresis systems].

Important criteria for assessing a cell separator are thrombocyte yield, separation efficiency and purity of the thrombocyte concentrates. Based on a Multicentric Counting Study in which twelve centers participated, we conclude that it is very difficult to compare the results of the various centers in regard to the separation efficiency. This is especially true for the comparison of different separation procedures. In Marburg we compared three different cell separators of the newest generation. COBE Spectra (n = 71), Fresenius AS-104 (n greater than 1100) and Fenwal CS-3000 TNX (n = 79). The COBE Spectra exhibited the best separation efficiency with the lowest leukocyte contamination (thrombocytes 4.3 x 10(11) (72.2%), leukocytes 0.5 x 10(7)) on the condition that the ACD-blood ratio did not differ more than -15% from the required algorithm. In order to reduce the risk to the donor, the system correspondingly reduces the donor's blood flow, resulting in a longer donation time (on the average 89-100 min). When the ACD ratio was reduced further, a considerable number of spontaneous and sometimes irreversible platelet aggregation occurred, increasing the risk of reduced platelet function and shortened survival. The AS-104 and the modified CS-3000 (TNX) had similar separation efficiencies (approx. 60%). While the platelet concentrates (PC) of the AS-104 almost reached the purity of that from the COBE Spectra, the leukocyte contamination of the CS-3000 PC's was still about four times higher. Other results published show that morphology, in vitro function and in vivo survival of thrombocytes collected with the AS-104 are significantly better than those with the CS-3000. Based on further criteria, the three systems were compared with each other. However, we could not come to a definite recommendation for any of the systems.

Blood Component Transfusion↗
PubMed1991

[Evaluating a new, fully automated blood separator with continuous blood flow].

The AS 104 separator provides for platelet yields in agreement with given standards. The number of undesired cells (leukocytes, erythrocytes) compares favorably with other technical separation systems. Concentrate volumes, total amount of ACD-A used, extracorporal blood volume and the reduction of donor blood cells are no challenge for the donor. The number of technical problems is not unusual for a new separation system entering into the first clinical evaluation. These data, as well as the deviation of yields, recommend further optimation. The technical optimation achieved so far and an expanded evaluation using statistical procedures permit an optimal, donor-independent (using variance analysis) or individual (using regression analysis) equilibration of the machine and permit the recognition of potential differences between different separators, centers or software versions, thus allowing the calculation of the number of runs needed to recognize differences from optimal standards.

Adult↗
PubMed1991

[Optimizing cell separation with the Cell Separator AS-106].

Seventeen different separation protocols based on more than 1100 thrombocytaphereses were tested. Twelve of these are reported on in this study. It became apparent that the most important variable is the centrifugation speed (1900 rpm at a blood flow of 50 ml/min). This made it possible to collect 3.5 to 3.8 x 10(11) thrombocytes (approx. 60% extraction efficiency) from 3.15 l blood. Further optimization of this procedure is desirable, since 10% of the thrombocytes still remain in the separation chamber. However, our optimization work was successful as far as the reduction of leukocyte and erythrocyte contamination is concerned, which ultimately resulted in leukocyte and erythrocyte contamination of about 1 x 10(7).

Blood Component Transfusion↗