No abstract

BACKGROUND A randomized controlled trial was conducted to test the effects of hydration and applied muscle tensing on presyncopal reactions to blood donation. Both interventions are designed to prevent the decreases in blood pressure that can contribute to such reactions, but due to the distinct physiological mechanisms underlying their pressor responses it was hypothesized that a combined intervention would yield the greatest benefit. STUDY DESIGN AND METHODS Prior to blood donation, first- and second-time blood donors (Mean Age = 20.2 years, SD = 4.9) were randomly assigned to: 1) standard donation, 2) placebo (leg exercise prior to venipuncture), 3) pre-donation water, or 4) pre-donation water and leg exercise during donation. RESULTS Main effects of group were observed for phlebotomist classification of vasovagal reactions, X2 (3) = 8.38, p<0.05, and donor reports of presyncopal reactions, X2 (3) = 13.16, p < 0.01. Follow-up analyses of phlebotomist classifications revealed fewer reactions in the pre-donation water and pre-donation water and leg exercise groups relative to placebo but not standard donation. Follow-up analyses of self-reported reactions revealed that women, but not men, had lower scores in both the pre-donation water and pre-donation water and leg exercise groups relative to both placebo and standard donation. CONCLUSION Pre-donation hydration and a combination of hydration and leg exercise may help attenuate presyncopal reactions in relatively novice donors, although future studies with larger samples are required to confirm this effect.

Although 2RBC donors were more likely to react, first-time 2RBC donors were no more affected by reactions than first-time WB donors. Experienced WB donors suffered a larger drop in retention as a function of reactions, in fact, than did experienced donors who gave 2RBC donations. Potential reasons for this data pattern require further investigation.