Family history of hypertension and vasovagal symptoms during blood donation.

Vasovagal reactions during blood donation were assessed in 185 individuals with and 298 individuals without a parental history of hypertension. It was predicted that individuals at genetic risk for hypertension would be less likely to faint or suffer pronounced vasovagal reactions, presumably by virtue of altered baroreflex sensitivity. A relationship between a parental history of hypertension and vasovagal responses was observed, albeit modified by blood donation experience and sex. Nurses obtaining blood from inexperienced donors without a parental history of hypertension were significantly more likely to recline the subject's chair than those obtaining blood from inexperienced donors with a parental history of hypertension or experienced donors. Questionnaire data were consistent with these findings. These results may be an interesting reflection of group differences in baroreflex sensitivity and have implications for screening potential donors.