A case-controlled multicenter study of vasovagal reactions in blood donors: influence of sex, age, donation status, weight, blood pressure, and pulse.

BACKGROUND: Vasovagal reactions occur in a small, but significant number of blood donors. These reactions may decrease return donation and disrupt blood collection activities. The purpose of this study was to define the contributory role of sex, age, weight, blood pressure, and pulse in vasovagal reactions with syncope in blood donors. STUDY DESIGN AND METHODS: A retrospective case-control study involved 1890 blood donors with syncope from three large United States blood centers during 1994 and 1995. Case controls and random population controls were used in a logistic regression analysis to determine the significance of individual variables to syncopal reactions. RESULTS: Female donors, young donors, first-time donors, low-weight donors, and donors with low predonation blood pressure had higher absolute donation reaction rates than other donors. When each variable was adjusted for other variables by regression analysis, age, weight, and donation status (first-time or repeat donor) were significant (p<0.0001), and sex, predonation blood pressure, and predonation pulse were not. The most important variables, in descending order, were age, weight, and donation status (first-time or repeat donor). CONCLUSIONS: Donation-related vasovagal syncopal reactions are a multifactorial process determined largely by age, weight, and first-time donor status.

The risk of acquiring Lyme disease or babesiosis from a blood transfusion.

To determine the risk of acquiring Lyme disease or babesiosis from blood transfusion, serum was collected before and 6 weeks after patients received multiple transfusions during cardiothoracic surgery and antibodies to Borrelia burgdorferi and Babesia microti were measured. Of 155 subjects, 149 received 601 total units of packed red blood cells (PRBC) and 48 received 371 total units of platelets. No patient developed clinical or serologic evidence of Lyme disease; 1 (who received 5 units of PRBC) developed clinical and serologic evidence of babesiosis. The risk of acquiring Lyme disease from a transfused unit of PRBC was 0 (95% confidence interval [CI], 0-0.5%) and from a transfused unit of platelets was 0 (95% CI, 0-0.8%); the same risks for babesiosis were 0.17% (95% CI, 0.004%-0.9%) and 0 (95% CI, 0-0.8%), respectively. The risk of acquiring either Lyme disease or babesiosis from a blood transfusion in Connecticut is very low.

Survival of Borrelia burgdorferi in blood products.

The incidence of Lyme disease is rapidly increasing in the United States. To assess the potential of transmission of the disease through blood transfusion, we studied the survival of Borrelia burgdorferi in blood products under blood bank storage conditions. Two units of whole blood, separated into red cells (RBCs), fresh-frozen plasma (FFP), and platelet concentrates (PCs), were inoculated with B. burgdorferi (strain B31) in concentrations of approximately 3000 organisms per mL of RBCs and FFP and 200 organisms per mL of PCs. Products were then stored under blood banking conditions and sampled at several storage times. The viability of the spirochete in blood components was determined by darkfield microscopic examination of cultures in modified Kelly's medium. The organism was shown to survive in RBCs (4 degrees C) and FFP (below -18 degrees C) for 45 days and in PCs (20-24 degrees C) for 6 days. The results of this study do not exclude the possibility of transmission of Lyme disease through blood transfusion.

Diabetes insipidus caused by extramedullary hematopoiesis.

Myeloid metaplasia involving the central nervous system is a rare occurrence most frequently found as an incidental finding at autopsy. A case is presented of a 56-year-old man with myeloid metaplasia and myelofibrosis, who developed diabetes insipidus. Postmortem examination revealed posterior pituitary involvement by extramedullary hematopoiesis with fibrosis and gliosis. Diabetes insipidus caused by extramedullary hematopoiesis is a rare event and is thus noteworthy.