The effect of processing method on the in vitro characteristics of red blood cell products.

BACKGROUND AND OBJECTIVES: While the clinical impact of differences in red blood cell (RBC) component processing methods is unknown, there are concerns they may be confounding variables in studies such as the ongoing 'age of blood' investigations. Here, we compare the in vitro characteristics of red cell concentrates (RCCs) produced by several different processing methods. MATERIALS AND METHODS: Nine processing methods were examined: three apheresis methods (Alyx, MCS+ and Trima), as well as leucoreduced whole blood-derived RCCs produced by buffy coat and whole blood filtration and non-leucoreduced RCCs. RCCs were stored in saline-adenine-glucose-mannitol or additive solutions (AS) 1 or 3 for 42 days, with quality tested on day 5 and day 42. RESULTS: Many significant product differences were observed both early in and at the end of storage. Mean haemoglobin (Hb) ranged from 52 to 71 g/unit and mean Hct from 59·5 to 64·8%. Most RCC passed regulated quality control criteria according to Canadian Standards Association guidelines, although there were some failures relating to Hb content and residual WBC counts. CONCLUSION: Processing method impacts RCC characteristics throughout storage; better understanding of these differences and reporting of processing method details is critical.

Impact of increasing sample volume from 4 ml to 8 ml on bacterial detection rates in apheresis platelets: a meta-analysis.

Some blood centres have increased sample volume of in-process cultures to improve detection of bacterial contamination when screening apheresis platelet units. We performed a meta-analysis to evaluate extant published North American data comparing apheresis platelet bacterial contamination rates from 4 ml and 8 ml sample volume. Pooled results indicate an 8 ml sample volume yields higher true-positive rates than 4 ml resulting in a significant increase in the detection rate and interdiction of contaminated units, which should contribute to reduced risk of adverse transfusion outcomes.

Factors associated with fainting: before, during and after whole blood donation.

BACKGROUND Whole blood (WB) donation encompasses several periods during which some donors faint. Identification of factors associated with fainting during each period should guide intervention strategies. Reducing faint reactions may reduce donor injuries and disability. METHODS Blood donation was divided into three periods: Period 1 - registration; Period 2 - phlebotomy; and Period 3 - post-phlebotomy. Period 3 consists of two sub-periods (3A - on-site and 3B - off-site). For each Period, stratified rates of fainting in relation to various donor and donation characteristics were calculated and multivariable logistic regression analyses to identify factors associated with fainting were conducted. Donor injuries in each period were also analysed. RESULTS Of the 956 766 donors registered in 2007, 554 534 (58%) donated WB. There were 43 fainting episodes and two injuries in Period 1 and 1520 faints and 73 injuries in Periods 2 and 3. Regression analyses showed that youth and donor first-time status are associated with fainting in all periods; but most significantly in Period 1. Small estimated blood volume is notably not a factor in Period 1 but is significant in Periods 2 and 3. The highest injury rate is seen in Period 3A (0·07 and 0·09/1000 donations) for male and female donors, respectively. CONCLUSIONS Variability in factors associated with fainting across defined periods of the donation process suggest differing underlying mechanisms and the possibility that interventions for the reactions most associated with injury during each time period can be designed. The highest rate of injury per donation occurred in ambulating donors.

Human T-cell lymphotropic virus infection among blood donors in south Florida. The Transfusion Safety Study Group.

Knowledge of the epidemiologic pattern of human T-lymphotropic virus (HTLV) in the United States is being enlarged by blood donor screening. We tested stored sera from 29,937 donations made in South Florida in 1984-1985. Twenty-three donors were confirmed as seropositive, a prevalence of 0.8 per 1,000 donations. Specificity was supported by serologic retesting and virus culture of 11 donors located for follow-up. Sex- and age-specific prevalences did not differ significantly; blacks, however, accounted for 65% of seropositive donations. Within South Florida, one section of Miami had a prevalence of 4.5 per 1,000 donations, significantly above the 0.1 to 1.1 per 1,000 rates for other parts. An epidemiologic association with known HTLV-I endemic areas could account for most infections; all seven typed isolates were characterized as HTLV-I. Exposures, however, were diverse, sometimes multiple, and had no necessary relationship to personal lifestyle. This finding suggests that sources of infection were varied. Seropositive family members emphasize familial clustering of HTLV-I infection.

Screening of selected male blood donors for p24 antigen of human immunodeficiency virus type 1. The Transfusion Safety Study Group.

BACKGROUND: The p24 antigen of human immunodeficiency virus type 1 (HIV-1) is sometimes detected before antibody (anti-HIV-1) is detectable in the serum of recently infected persons. This has led to the consideration of p24-antigen testing for routine screening of blood donors. METHODS: To estimate how many HIV-infected seronegative donors would be identified if p24-antigen screening was introduced, we tested selected donations from a repository of 200,000 serum samples from voluntary donors that was established in late 1984 and early 1985. The 8597 serum samples selected for p24-antigen screening were chosen because their donors had demographic characteristics known to be associated with a high prevalence of seropositivity. RESULTS: The prevalence of anti-HIV-1 antibodies in the 1984-1985 serum samples selected for p24-antigen screening was 1.54 percent--more than 100 times the 0.012 percent prevalence in present-day donations in the United States. The antigen was detected in 15 of 132 serum samples (11.4 percent) from donors who had already been confirmed as seropositive. No instance of confirmed positivity for p24 antigen was found among the 8465 seronegative serum samples. CONCLUSIONS: These data indicate that the yield of screening for p24 antigen in volunteer donors to identify HIV-1 carriers would be negligible. We therefore recommend against routine screening with currently available p24-antigen assays.

Epidemiologic background of blood donors with antibody to human T-cell lymphotropic virus. Transfusion Safety Study Group.

We interviewed 51 blood donors in four major US metropolitan areas subsequently found to have had antibodies to human T-cell lymphotropic virus (anti-HTLV) in late 1984-early 1985. Sixteen donors (31%) reported that they or a sexual contact had a history of blood transfusion. Twelve donors (24%) reported that they or a sexual contact used intravenous drugs. Ten donors (20%) were blacks born in the southeastern US. Four of the male donors (15%) reported homosexual contact. The most common characteristic was an association with Japan or the Caribbean basin (61%). These results show a broader variation of epidemiologic backgrounds than anticipated.

Current autologous transfusion practices. Implications for the future.

A questionnaire was distributed to 509 AABB institutional members to evaluate current autologous transfusion practices. Results were returned from 47 blood centers, 108 transfusion services and 64 hospital blood banks (response rate 43%). Results indicate that not all eligible patients are allowed to donate due to unnecessarily strict eligibility criteria. Thirty percent of autologous units are not tested for infectious disease markers. Of those units tested and found positive for anti-HIV or HBsAg, 53 and 72% respectively, of the institutions provide the units to the intended recipient. Forty-seven percent of institutions perform an AHG crossmatch for autologous recipients. Sixty five percent of institutions permit "crossing-over" of autologous units for homologous use. Implications of these findings for the development of standards for autologous transfusion programs are discussed.

Automatic special case consultations in transfusion medicine.

In the past, consultations in immunohematology were usually delivered only when there was a blood or component shortage, or when the time required for compatibility testing was prolonged due to the presence of a difficult recipient antibody problem. More recently, transfusion medicine physicians have increased their role as clinical consultants concerned about the appropriate indications for blood transfusion. This communication presents a way to begin a sound program of clinical transfusion medicine consultation. The program can fit with community-wide teaching efforts, community or hospital transfusion audits, and specific physician education programs. Automatic or unsolicited consultations appear to have been both accepted well and beneficial in large hospitals and in communities where they have been provided for more than 7 years.