Prediction of Fainting in Blood Donors

Four hundred and fourteen consecutive blood donors to a hospital blood bank were studied to discover items of value in predicting the occurrence of "reactions." Since it is probable that blood donor "reactions" are almost always vasovagal faints, they are so referred to below. Several items of predictive value were found: none of the 62 Negroes, but 63 of the 352 white persons fainted; the younger the donor, the more likely a faint; the higher the resting pulse rate before venipuncture, the more likely a faint; admission of "nervousness" was associated with greater chance of fainting than was denial. Sex, resting blood pressure before venipuncture, and history of previous blood donation did not significantly differentiate fainters from nonfainters. The data are compatible with the hypothesis that vasovagal fainting in blood donors is the second limb of a diphasic response, and is part of relief from anxiety; the first limb is part of anxiety proper.