Granulocyte Chemotaxis

The under agarose method for evaluation of leucocyte chemotaxis was used to investigate the effect of radiographic contrast media (CM) on granulocyte locomotion. The CM tested had no chemoattractive properties. CM inhibited N-fmlp, a synthetic formylated Met-tripeptide, which is a strong chemotactic agent and an analogue to chemotatic peptides produced by bacteria. The inhibition of N-fmlp was most pronounced for diatrizoate. Equiosmolal saline was not so inhibitive. Therefore, some part of the inhibition was caused by factor(s) other than hyperosmolality inherent in the CM solution.

Influence of Radiographic Contrast Media on Phagocytosis

To evaluate the influence of radiographic contrast media (CM) on human polymorphonuclear leucocytes (PML), the ability of these cells to ingest latex particles after in vitro exposure to five different radiographic contrast media was investigated. All CM inhibited the phagocytic properties of PML. The inhibition was dose dependent. The inhibitory effect was partly due to hyperosmolality but CM specific inhibition was also evident.

Granulocyte Adherence after Intravenous and Intraarterial Injection of Ioxaglate or Iohexol

The effect of iohexol and ioxaglate on granulocyte adherence to nylon fibers was investigated with blood from 15 patients undergoing angiography, and from 24 patients undergoing excretory urography. Decreased adherence and increased numbers of granulocytes in the circulation were observed soon after injection of iohexol or ioxaglate in the aorta, or injection of ioxaglate i.v. Increased adherence and decreased numbers of granulocytes in the circulation were observed soon after injection of iohexol i.v. The differences were small soon after the injection of contrast media (CM). More pronounced decreased adherence and increased numbers of granulocytes were detected 2 and 5 hours after injection in the aorta for both CM.

Granulocyte Adherence is Inhibited by Radiographic Contrast Media in Vitro

Different amounts of diatrizoate, ioxaglate, iohexol, iodixanol, NaCl 1000 mOsm/kg, mannitol 1098 mOsm/kg, and meglumine (meglumine concentrations corresponding to the content in the diatrizoate solutions) were added to either whole blood or a suspension of granulocytes in autologous plasma, and the adherence to nylon fibers was determined. At high concentrations all the investigated contrast media (CM) inhibited granulocyte adherence. The degree of inhibition was significantly greater when the ionic CM diatrizoate and ioxaglate were used, as compared with the nonionic media. Meglumine solutions at high concentrations also inhibited adherence but significantly less than diatrizoate solutions containing the same amount of meglumine. Diatrizoate showed the greatest inhibitory effect on granulocyte adherence, and significant inhibition could be detected even with a 1.25% solution.

Granulocyte Chemotaxis

One of the important functions of granulocytes is the ability to respond to a chemoattractive signal by migration. The influence of radiographic contrast media (CM) on the chemoattractive properties of serum was investigated by under agarose technique for chemotaxis. No chemotactic response was seen when serum was incubated with different concentrations of CM after heat inactivation. The CM did not generate the heat stable complement split product C5a-desarg which would have resulted in a chemotactic response. Without heat inactivation all complement available in the serum was activated by the agarose in the chemotaxis assay. Low concentrations of iohexol and iodixanol brought about an increased chemotactic response relative to a reference with saline instead of CM. This may be due to activation of heat labile chemoattractants from other sources than the complement cascade. At high concentrations of all five investigated CM, a decreased number of granulocytes migrated over a shorter distance when compared with the reference, and this may be due to interactions between the CM and chemoattractants or their precursors.

Granulocyte Chemotaxis before and after Urography

Granulocytes isolated from whole blood of 10 volunteers with Hypaque/Ficoll or Percoll gradient centrifugation showed a significant inhibition of their chemotactic response when incubated with diatrizoate. The influence of 4 different i.v. injected radiographic contrast media (CM) on granulocyte chemotaxis was evaluated using the under agarose assay. Each CM was injected in 10 consecutive outpatients referred for urography. Cells and serum were obtained before and 20 min after the injection of CM. Autologous serum was used as chemoattractive agent, and the cell suspensions from both samples were tested against serum drawn both before and after the injection of CM. No significant changes in granulocyte chemotaxis or the chemotactic potential of serum were seen. Furthermore, there was no change in the chemotactic response towards homologous serum or N-fmlp after injection of diatrizoate or iohexol. In conclusion, the investigation did not unveil any change in granulocyte chemotaxis 20 min after the injection of CM in the 40 subjects studied.

Radiographic Contrast Media and Release of Neutrophil Specific Proteins in Vitro and after Intravenous Injection

The neutrophil granulocytes contain granules in which different proteins are present. When activated the neutrophils degranulate and thereby release some of these proteins to the surroundings. Some of these proteins are specific for this type of cell, e.g., lactoferrin and elastase. To investigate the influence of contrast media (CM) on this release, blood was incubated with diatrizoate, ioxaglate, iohexol, iodixanol, hyperosmolar saline, and hyperosmolar mannitol at different concentrations, and the amount of the neutrophil specific proteins lactoferrin and elastase were measured. Decreasing protein concentrations were observed for increased medium concentrations, suggesting that the degranulation process of the neutrophils was inhibited by the CM. The protein concentrations were lowest after incubation with the two ionic media diatrizoate and ioxaglate. Significantly decreased values of plasma lactoferrin were observed one min after i.v. injection of iohexol or ioxaglate in 82 patients undergoing urography. There was no significant difference between the two CM.

Phagocytic Properties of Granulocytes after Intravenous Injection of Ioxaglate or Iohexol

To evaluate the influence of radiographic contrast media (CM) on human granulocytes, the ability of these cells to ingest latex particles after intravenous injection of ioxaglate and iohexol was investigated. Both CM inhibited the phagocytic properties of granulocytes; the inhibition was the most pronounced immediately after the injection, but inhibition was also observed 60 min after injection of ioxaglate. The inhibition 1 and 5 min after injection of CM was more pronounced after injection of ioxaglate than after injection of iohexol. However, this difference between the 2 CM was not significant. Significant inhibition of phagocytosis was found for mannitol solutions with osmolalities higher than 369 mOsm/***1. Significant inhibition of phagocytosis was observed when granulocytes were isolated with either Hypaque/Ficoll or Percoll gradient centrifugation and then incubated with diatrizoate. Thus the ability of granulocytes to phagocytize latex particles was inhibited after i.v. injection of 50 ml ioxaglate or iohexol. Part of this inhibition may be due to hyperosmolality.

Decline in hepatitis B infection observed after 11 years of regional vaccination among Danish drug users

The aims of this study were to determine the current prevalence of viral hepatitis and HIV among drug users, and to compare this prevalence with previous findings in the same geographical region. Cross-sectional surveys of drug users attending treatment centers on the island of Funen with approximately 500,000 inhabitants were administered in 1996 and 2007. The 2007 prevalence estimates were: anti-HBc 50.2%, HBsAg 0.9%, anti-HCV 66.8%, HCV-RNA 40%, and anti-HIV 1.1%. The corresponding 1996 prevalence values were: anti-HBc 70% (P < 0.0001), HBsAg 9.8% (P < 0.0001), anti-HCV 82.8% (P < 0.0001), HCV-RNA 56.3% (P = 0.002), and anti-HIV 1% (P = 1). The 2007 prevalence of viral hepatitis decreased due to the increasing proportion of non-injectors. Among injectors, the prevalence remained unchanged except for a significant decrease in HBsAg. The 2007 prevalence of ongoing HBV infection among infected (HBsAg/anti-HBc proportion) was the lowest that to our knowledge has been reported among drug-users. Vaccination coverage among susceptible persons tested in 2007 was 24%, compared to 0.7% in 1996. Therefore, despite an unchanged prevalence of anti-HBc among injecting drug users, a highly significant drop in HBsAg prevalence was seen during the last decade. This observation may be linked causally to an increase in hepatitis B vaccination of the susceptible population. Our findings suggest that even incomplete vaccination, without persistent protective anti-HBs levels, may induce an immune memory sufficient to prevent chronic infection upon transmission.

One-year period prevalence of blood transfusion

Transfusion practice is reported to differ considerably between countries. Comparisons often rely on transfusion rates, incidence - or prevalence rates. In this paper, the one-year period prevalence rate (1-YPPR) of transfusion of red cells (RBC) is presented. Transfusion data, demographic data and patient data were retrospectively combined to calculate sex and diagnosis specific and age standardized 1-YPPR s of RBC transfusion for the complete population in a Danish county. During the calendar year of 2006, 4427 patients received RBC transfusion in Funen County. The crude 1-YPPR of RBC transfusion was 9.2/1000 citizens. Most of the transfused patients had a main diagnosis of neoplasm (22% of recipients), diseases of the circulatory system (15%), the digestive system (15%), injuries (13%) and diseases of the blood (8%). Age standardization reversed the relation between sex specific 1-YPPRs, yielding a statistically significantly higher 1-YPPR in males (6.8/1000) vs. females (6.3/1000). The method for calculating a diagnosis specific 1-YPPR of transfusion of RBC is presented and proposed as an option for comparison of transfusion practice with other transfusion centres. The crude and the diagnosis specific 1-YPPR s are found to increase with age. Thus, age standardization of crude prevalence rates is necessary for meaningful comparisons between populations.

Hepatitis B vaccination in prison with a 3-week schedule is more efficient than the standard 6-month schedule

A randomized study of injecting drug users in a Danish prison comparing vaccination at 0, 1 and 3 weeks with the 0, 1 and 6 months schedule (20microg Engerix B i.m.) was conducted. Due to a low participation rate, a second nonrandomized study was conducted in Estonia where all prisoners were vaccinated with the short schedule. In the randomized study, the compliance with three doses was 63% (12/19) in the 3-week schedule compared to 20% (3/15) in the 6-month schedule (P = 0.017). In the nonrandomized study, the compliance was 81% (457/566) and the seroprotection rate at month 7 was 67% (97/145), resulting in protection of 54% of the population at risk. This was significantly higher than the estimated 34-42% protection that would have been achieved with the 6-month schedule.

Monitoring transfusion practice--a computerized procedure

As the description of transfusion practice over time requires the handling of massive amounts of data, and because the majority of records have until now been paper-based, little is known about the epidemiology of blood transfusion. Furthermore, most previous studies have collected data manually from patient records or from computerized registers created solely for study purposes. We describe a procedure for monitoring transfusion practices based exclusively upon the collection of data from the existing computerized registers. During the calendar years 1997 and 1998, more than 750 000 data records were collected from the blood transfusion registers, diagnosis and procedure registers, and clinical biochemistry registers at two university hospitals. Linking of the data required a unique and consistent identification of all data records. This was made possible by the national Personal Identification Number. In this way more than 98% of all transfusions could be identified and approximately 95% (77 950) could be connected to a principal diagnosis. The described procedure creates new opportunities for studies of transfusion practices both on a large scale and in richness of detail, and we propose to establish a network where transfusion practices data are available and comparable for individual departments, hospitals, whole regions, and possibly nations.

[Blood donors at the county of Funen. Status based on more than five years of experience, 1995-2000]

INTRODUCTION

The Danish blood donor organisation is considered to be one of the best organised in the world. At the same time, Denmark has very high numbers of blood donations and blood transfusions, compared to the number of inhabitants. In recent years, pressure has been put on the donor organisation, owing to a decline in the number of donors and because new treatment modalities and other initiatives take blood transfusion for granted.

MATERIAL AND METHODS

Information from the electronic databases of the County of Funen Transfusion Service on all blood donors in the county and its donor organisations from 1995 to September 2000 was extracted and analysed.

RESULTS

In September 2000, the County of Funen had 21,087 active blood donors organised in eight bodies, i.e. 4% of the inhabitants. There are significant differences between these bodies, but common to all is a relative lack of donors between the age of 18 and 35 years. Each year about 10% of the donors withdraw, which is equal to 14,127 donors in the period analysed. This withdrawal is only partly balanced by 7820 new donors, with the result that the total number of donors in the county is declining by an average of 1100 donors a year.

DISCUSSION

Several possibilities for action are proposed, for instance intensive recruitment campaigns, mobile blood drawing units, a change in the opening hours of blood banks, optimisation of the stocks, but, above all, the possibilities of reducing the amount of blood needed for transfusion. The Funen as well as the Danish health authorities must realise that blood for transfusion is no longer in unlimited supply, but in the future will be a rather restricted good.

Hepatitis B core antibodies in Danish blood donors: a surrogate marker of risk behaviour

BACKGROUND AND OBJECTIVES

The aim of this work was to determine the prevalence of antibodies to hepatitis B core antigen (anti-HBc) among Danish blood donors and to correlate this with risk factors for blood-borne and sexually transmitted diseases.

MATERIALS AND METHODS

During a 5-month period, 10 862 consecutive donors in the County of Funen were screened for anti-HBc, and repeat-reactive samples were confirmed by supplementary testing. Information on risk factors was assessed by questionnaire in 585 consecutive anti-HBc-negative blood donors and compared with information obtained from confirmed positive donors.

RESULTS

The prevalence of confirmed positive anti-HBc among donors was 0.70% (76/10 862, 95% confidence interval [CI]: 0.55-0.87). One donor was positive for anti-HBc immunoglobulin M (IgM); none tested positive for hepatitis B virus (HBV) DNA. In a logistic regression analysis, age, female gender, tattoos and commercial sexual relations, were independent predictive factors for the presence of anti-HBc.

CONCLUSION

Anti-HBc is a surrogate marker for previous risk behaviour in the Danish blood donor population. We suggest that screening for anti-HBc may be used among new donors to supplement interviews on risk behaviour.

Prevalence and incidence of bloodborne viral infections among Danish prisoners

In order to determine the prevalence and incidence of bloodborne viral infections among prisoners, we conducted a prospective study in a Danish medium security prison for males. The prisoners were offered an interview and blood test for hepatitis and human immunodeficiency virus HIV at inclusion as well as at release from prison or end of study. Of 403 prisoners available 325 (79%) participated in the initial survey and for 142 (44%) a follow-up test was available. 43% (140/325) of the participants were injecting drug users (IDUs) of whom 64% were positive for hepatitis B (HBV) and 87% for hepatitis C (HCV) markers. No cases of HIV or human T lymphotropic virus (HTLV) were found. 32% of all prisoners could transmit HBV and/or HCV by blood contact. 70% of IDUs had shared injecting equipment, and 60% had injected inside prison. Only 2% of IDUs were vaccinated against HBV. Duration of injecting drug use, numbers of imprisonments, and injecting in prison were independently and positively associated with the presence of HBV antibodies among IDUs by logistic regression analysis. The HBV incidence was 16/100 PY (95% CI: 2-56/100 PY) and the HCV incidence 25/100 PY (1-140) among injecting drug users (IDUs). We conclude that IDUs in prison have an incidence of hepatitis B and C 100 times higher than reported in the general Danish population. They should be vaccinated against hepatitis B and new initiatives to stop sharing of injecting equipment in and outside prison is urgently needed.

Outbreak of Hepatitis B among injecting drug users in Denmark

BACKGROUND

The incidence of hepatitis B is low in Denmark, but injecting drug users (IDUs) remains a high-risk group for this infection.

OBJECTIVES

The aim of the study was to describe a hepatitis B outbreak among IDUs by comparing existing registers. Additionally, we wanted to analyze the genetic variation of the hepatitis B virus involved in the outbreak.

STUDY DESIGN

In the County of Funen, registers of laboratory diagnosis, hospital records and reports from clinicians to the Medical Officer of Health (MOH) were compared between 1992 and 1998. HBsAg positive sera recovered from the epidemic were sequenced and compared to known HBV strains.

RESULTS

We identified 648 cases of hepatitis B of which 51% (332) were acute infections. The laboratory database identified 96% (319/332) of these, 45% (150/332) were admitted to hospital and 38% (127/332) were reported to public health. By capture-recapture analysis based on MOH reports and hospital records the estimated total number of acute cases were 334 (95% C.I. 283-385). We sequenced 75 HBsAg positive samples and identified two very similar strains of genotype D (serotype ayw3) among IDUs involved in the outbreak.

CONCLUSIONS

The current surveillance system did not detect the majority of acute hepatitis B cases in County of Funen. We suggest laboratory-based surveillance of hepatitis B to be implemented at a national level as this may identify new outbreaks faster and more complete than the current surveillance system.

Leukocyte-depletion of blood components does not significantly reduce the risk of infectious complications. Results of a double-blinded, randomized study

Allogeneic blood transfusions are claimed to be an independent risk factor for postoperative infections in open colorectal surgery due to immunomodulation. Leukocyte-depletion of erythrocyte suspensions has been shown in some open randomized studies to reduce the rate of postoperative infection to levels observed in nontransfused patients. Using a double-blinded, randomized design, we studied the postoperative infection rate in patients undergoing open colorectal surgery transfused with either leukocyte-depleted erythrocyte suspensions (LD-SAGM) or non-leukocyte-depleted erythrocyte suspensions (SAGM). Unselected patients (n 279) were allocated to receive LD-SAGM (n 139) or SAGM (n 140) if transfusion was indicated. Forty-five percent were transfused, yielding 48 patients in the LD-SAGM group and 64 in the SAGM group. Thirteen patients were excluded because they received one type of transfusion in spite of randomization to the other type. No significant differences in the rates of postoperative infections (P=0.5250) or postoperative complications (P=0.1779) were seen between the two transfused groups. Infection rates were 45% and 38% in the transfused groups and 21% and 23% in the nontransfused groups. No significant difference between the transfused groups was seen on any single infectious event, mortality rate, or duration of hospitalization. Leukocyte-depletion of erythrocyte suspensions transfused to patients undergoing open colorectal surgery does not reduce postoperative infection rates.

Monitoring transfusion practices at two university hospitals

BACKGROUND AND OBJECTIVES

Considering the clinical importance of blood transfusions, the limited knowledge of transfusion practices is remarkable. New methods are needed to elucidate the observed variation of transfusion practices.

MATERIALS AND METHODS

All patients transfused or pretransfusion tested (i.e. at risk for blood transfusion) at two tertiary teaching hospitals during the full years of 1997 and 1998 were included in the study.

RESULTS

The observed practices contained substantial variance at the level of hospitals. The contributions to the total variance of the different specialities were highly significant, as was the contribution of hospitals to the variance in plasma and platelet transfusions. Significant interactions between hospitals and specialities were observed in transfusion of red cells, plasma and platelets.

CONCLUSION

To our knowledge this is the first survey of this size to combine transfusions, diagnoses and biochemical tests, exclusively based on an existing computerized register. The aim is to establish a basis for comparison of local transfusion practices with other commensurate hospitals and regions at a national (and international) level.

From serological to computer cross-matching in nine hospitals

In 1991 it was decided to reorganise the transfusion service of the County of Funen. The aims were to standardise and improve the quality of blood components, laboratory procedures and the transfusion service and to reduce the number of outdated blood units. Part of the efficiency gains was reinvested in a dedicated computer system making it possible--among other things--to change the cross-match procedures from serological to computer cross-matching according to the ABCD-concept. This communication describes how this transition was performed in terms of laboratory techniques, education of personnel as well as implementation of the computer system and indicates the results obtained. The Funen Transfusion Service has by now performed more than 100.000 red cell transfusions based on ABCD-cross-matching and has not encountered any problems. Major results are the significant reductions of cross-match procedures, blood grouping as well as the number of outdated blood components.

Detection of irregular red cell antibodies: more than 3 years of experience with a gel technique and pooled screening cells

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate more than 3 years of experience with a gel technique in combination with pooled screening cells for the detection of irregular red cell antibodies.

MATERIALS AND METHODS

Conventional serologic methods were used for blood typing, antibody screening and cross-matching until the end of 1992. We introduced the gel technique as a routine assay for antibody detection and identification in 1993.

RESULTS

After the tube technique had been abandoned, the number of false-positive antibody screening tests was reduced by 71%, positive antibody screening tests by 33%, enzyme agglutination by 100% and rouleaux reactions and cold-reacting antibodies by more than 50%. There was a 40% increase in first-time detection of clinically relevant antibodies. We saw no increase in delayed haemolytic transfusion reactions.

CONCLUSIONS

For the detection of irregular red cell antibodies, pooled screening cells in combination with a gel technique are at least as efficient and safe as a conventional tube technique with unpooled test cells.

[Transfusion service of the county of Funen. Organizational and economical aspects of restructuring]

The reorganization of the transfusion service in the County of Funen during the period from 1990 to 1996 is described. The professional responsibility for the transfusion service was delegated to the county's only department with specialists in transfusion medicine. The responsibility for economy and personnel remained decentralized. Standard operation procedures for collection and production of blood components and for blood group serology were standardized resulting in higher quality. The number of collections were reduced from 47,000 to 35,000 in spite of an unchanged number of transfused units (approx. 31,000 per year). The outdating was reduced from 35 to 2%. A computer system was implemented resulting in rationalized flow of work and the introduction of a computer crossmatch. From 1997, when the computer system will have been paid for, the county and the university hospital will gain DKK 1.6 million and DKK 2.0 million per year respectively as a result of the reorganization.

[Rational transfusion therapy. A study of transfusion practice and possibilities of optimization in elective coronary bypass surgery]

The objective of the study was to evaluate the effect of intervention on physicians' transfusion behavior in elective coronary artery bypass grafting (CABG). We analyzed transfusion data on 176 patients who underwent primary elective CABG during two periods, either before (phase one, n = 102) or after (phase two, n = 74) intervention. The intervention was based on cooperation with the involved department of cardiac surgery, interviews of the surgeons and anaesthesiologists ordering blood, and concurrent audit of transfusion practice using a blood order form. The proportion af patients receiving allogenic transfusions decreased from 90% in phase one to 58% in phase two and the total use of blood components was reduced from an average of 6.3 units/patient to 2.7 units/patient, p < 0.01. Indications for transfusion documented in the medical record increased from 19% in phase one to 63% in phase two. It is concluded that intervention on physicians' transfusion behavior can improve the transfusion therapy in patients who undergo elective CABG.

[Use of fresh frozen plasma in patient treatment. Indications illustrated by a literature review and a study of practice at a university hospital]

We analyzed transfusion data on all patients transfused with fresh frozen plasma (FFP) during two periods of four weeks, before (phase one) and after (phase two) initiation of information and intervention. Information was based on the results of phase one and on information about appropriate use of FFP. The intervention consisted of introducing a new policy: Clinicians had to justify their prescription of FFP to the physician on duty in the blood bank. During phase one, the usage of FFP was 403 units, which decreased to 229 units during phase two (43% reduction). In both phases an unchanged proportion of FFP units (68%) were preceded by coagulation tests. In phase one, only 90 (22.3%) of the instances had documented coagulopathy by laboratory criteria, whereas in phase two the number was 77 (33.6%). A total of 186 (46.4%) FFP units in phase one were considered inappropriately transfused compared to a total of 89 (38.9%) units in phase two. Indications for transfusion were stated for 80 (19.9%) FFP units during phase one increasing to 114 (49.8%) units during phase two. Through information and intervention we were able to reduce the usage of FFP by 43%. The results reveal a need for quality assurance of the use of transfusions with FFP.

[Use of blood products in Denmark in 1993. Regional differences and comparison with other Scandinavian and European countries]

In Denmark approximately 396,000 units of blood were collected during 1993 from among approximately 270,000 voluntary non-renumerated blood donors corresponding to about 76 donations per 100 inhabitants. Almost all units (approx. 99%) were fractionated into blood components in the blood banks. Approximately 16,000 erythrocyte units were rejected due to technical errors or quality control, while around 37,000 erythrocyte units were discarded from stock. Only 190 units were transfused as whole blood. In all 327,108 SAG-M erythrocyte suspensions, 70,971 thrombocyte concentrates, 50,161 units of fresh frozen plasma, FFP, and approximately 1700 kg albumin, 100% were transfused, corresponding to 63, 14 and 10 units and 340 g per 1000 inhabitants. When compared to other Scandinavian and European countries, Denmark has a high consumption of erythrocyte components, FFP and albumin for transfusion. The reason why cannot be clarified by available data, but it is not unlikely that Denmark has a more liberal transfusion policy than the other countries. There are considerable differences within Denmark as regards the clinical use of blood products. Counties/regions with university hospitals and regional and/or national functions tend to have a relatively high consumption. However, no information exists on consumption related to demographic parameters or related to hospitals, departments or diagnoses.

Preparation of white cell-reduced red cells by filtration: comparison of a bedside filter and two blood bank filter systems

BACKGROUND

Concern has been raised about the quality of white cell (WBC)-reduced red cells (RBCs) obtained by bedside filtration. The bedside performance and workload of a routine bedside filter have been compared to the laboratory performance and workload of two blood bank filter systems.

STUDY DESIGN AND METHODS

Buffy coat-depleted saline-adenine-glucose-mannitol (SAGM) RBCs (90 units) were prepared. Thirty units were filtered with each of the two blood bank filter systems, and 30 units were filtered (but not transfused) with the bedside filter in a clinical department after 8 to 24 days of storage. The RBCs lost and the postfiltration WBC content (Nageotte chamber) were determined for all filtered units, and the workload associated with filtration by each of the filter systems/filter was assessed. Units with a postfiltration content of > or = 2 x 10(6) WBCs were regarded as filtration failures.

RESULTS

Four (13%) of the 30 units filtered at the bedside were filtration failures, compared to no failures with either of the blood bank filter systems. In addition, the median WBC content (0.14 x 10(6)) of the units filtered at the bedside (2 units/filter) was significantly higher than that of the units filtered in the blood bank (0.05 x 10(6)). The RBC loss was significantly higher with the filter systems than with the bedside filter, provided 2 units per filter were processed with the latter. The timed workload of the filter systems was 45 to 75 minutes per 12 units, which was similar to the time required for bedside filtration.

CONCLUSION

Bedside filtration of 2 units of stored buffy coat-depleted SAGM RBCs per filter resulted in a higher incidence of filtration failure and higher postfiltration WBC content than did laboratory filtration of 1 unit of fresh buffy coat-depleted SAGM RBCs per filter with either of two blood bank filter systems.

An antibody screening test based on the antiglobulin gel technique, pooled test cells, and plasma

The recently introduced gel technique offers significantly advances compared to traditional tube tests. The purpose of the present study was to design an antibody screening test based on the gel technique, pooled cells, and plasma and to evaluate this test by comparison with a conventional spin-tube indirect antiglobulin test (IAT) combined with a two-stage papain technique. Pilot studies were performed to establish optimal parameters during the design phase, and finally 5,446 consecutive samples were screened for irregular antibodies by the gel technique in parallel with routine techniques. Irregular erythrocyte antibodies were detected in 151 samples, and the gel technique proved equal or superior to the tube test in the detection of all antibodies except 'enzyme-only' anti-E and anti-Lea. We conclude from this study that screening for unexpected antibodies using the gel IAT in our set-up, which includes: (1) omission of enzyme technique; (2) the use of stabilized (EDTA) plasma instead of serum as test material in order to facilitate automation; and (3) pooling 2 by 2 of 4 test cells (to make the gel technique price competitive), is a fast, reliable and sensitive procedure that maintains transfusion safety and compares favourably with our previous routine of saline IAT combined with a two-stage papain technique.