The quest to reduce vasovagal reactions in young blood donors

Vasovagal reactions in whole blood donors consist of symptoms like dizziness, sweating, pallor, and anxiety and generally occur on the donor bed toward the end of the phlebotomy. Reactions affect blood donor safety and comfort and decrease blood donor return rates.1 Syncope occurs in approximately 4 to 5%2 of vasovagal reactions and 0.12%2 to 0.27%3, 4 of all allogeneic whole blood donations. Sixty percent3 of syncopal reactions occur after the donor leaves the donor bed, with 10% to 12%3, 5 of reactions occurring after the donor leaves the donation site. Syncope after the donor stands up is an issue because if the donor falls, approximately 4% to 9% sustain an injury.2, 3 The donor injury rate for allogeneic whole blood donations is 0.011%2 to 0.014%.3 Overwhelmingly, the injuries are minor; but there can be severe injuries such as fractures, lacerations, and closed-head injuries. Syncope in a donor driving a motor vehicle, although rare, can cause an accident. Fifty-four percent of reactions occur in blood donors who are 22 years old or younger.2 This observation is due to higher risk in young donors and to the large proportion of young donors.6, 7 The proportion of blood donations from 16- to 18-year-old donors was 16% at the American Red Cross (ARC) during the 2009 to 2010 school year,8 and most states now permit 16-year-olds to donate blood with parental consent. In this light, AABB highlighted strategies to reduce vasovagal reaction rates in younger blood donors.9 The two largest blood center systems, ARC and Blood Systems, Inc. (Blood Systems), led the way in evaluating their substantial data and implementing practices to reduce vasovagal reaction rates in young blood donors.8, 10 The new national donor hemovigilance program may provide the same opportunity for single blood centers.11 This editorial reviews and praises what has been done so far to reduce vasovagal reactions in young donors, states the limitations observed, and evaluates what more can be done in the future to reduce vasovagal reaction rates based on current knowledge. Efforts to reduce vasovagal reactions in young blood donors in two major blood collection systems have centered on three interventions: requiring young donors (16-18 years old or less than 23 years old) to have estimated blood volumes (EBVs) that exceed 3500 mL to ensure that less than 15% of the EBV is donated,7, 8, 10, 12 encouraging young donors to drink 473 to 500 mL of water just before the donation,13, 14 and encouraging donors to apply muscle tension during the blood donation.15, 16 There have been other actions to educate donors, improve blood drive setup, improve the blood donation process, and have an adequate number of competent and concerned staff.9 Thus, predonation information for the blood donors, their parents, school administrators, the school nurse, and blood drive sponsors and chairpersons improves understanding of the donation process and its risks. Donors who are waiting to donate should not have direct line of sight to donor reactions as there is a psychological component to vasovagal reaction precipitation. Staff should provide descriptive explanations during the donation process to keep donors informed and engaged and particularly during the phlebotomy stage. Donors should be stable in a sitting position on the donor bed before being released from the bed, and donors should be encouraged to stay at the refreshment site for a period of time to ensure their well-being. A more comprehensive review of suggestions can be found in AABB's 2008 Bulletin on Strategies to Reduce Adverse Reactions and Injuries in Younger Donors.9 In the most recent ARC study,8 754,000 and 711,000 whole blood donations from 16- to18-year-old donors in the 2008 to 2009 and 2009 to 2010 school years, respectively, were compared to a baseline of 2.02 million donations by donors of the same age in school years from 2005 to 2006 through 2007 to 2008. Actions in the 2008 to 2009 school year included new predonation materials for high school students and their parents, standard work guidance for staffing levels and the donation process, elimination of the view of the venipuncture area from the waiting area, encouraging each donor to drink 16 oz of water before phlebotomy and to perform leg lifting as a form of muscle tension, and a requirement for all large blood drives to have a supervisor without collection responsibilities. In the 2009 to 2010 school year, each donor had to have an EBV of at least 3500 mL. The presyncope reaction rates decreased by 33, 25, and 18% in 16-, 17-, and 18-year-old donors, respectively, in comparison to the baseline group. Fifty-five percent of the decrease in 16-year-old donors occurred in 2008 to 2009 and 45% in 2009 to 2010. ARC's net decrease in its presyncope reaction rate for 16- to 18-year-old donors was 21%. The syncope rate decreased by 14% in 16-year-old donors in 2009 to 2010, and there was no decrease in the syncope rate in 17- and 18-year-old donors. The overall decrease in the syncope rate was 4%. There was no change in the donor injury rate. In sum, ARC found that its changes led to a 21% decrease in the presyncope rate, a 4% decrease in the syncope rate, but no change in the donor injury rate. Blood Systems performed a similar comparison of vasovagal reaction rates in 17- to 22-year-old donors for two periods.10 There were no interventions for the 99,859 donations in calendar year 2007, which was used as the baseline. For the 113,172 donations between August 1, 2008, and July 31, 2009, the three interventions used were the offer of 473 to 500 mL of water to each donor; encouraging donors to apply muscle tension in the lower legs and buttocks for 5 seconds alternating with 5 seconds of relaxation, starting at phlebotomy; and elimination of donors with EBVs of less than 3500 mL. The total reaction rate decreased by 24%, and syncope decreased by 22%. For females, there was a 20% reduction in the total vasovagal reaction rate, including a 17% decrease in the presyncope rate and a 21% decrease in the syncope rate. The off-site syncope reaction rate in women also decreased by 40%. This reduction is important because donors with off-site syncope are more frequently injured and sent to hospital emergency rooms than donors with similar reactions that occur at the donation site.5, 17 Comparison of preintervention donations by donors with EBVs exceeding 3500 mL to postintervention donations allowed evaluation of the combined effects of water and muscle tension. The comparison showed a 12% decrease in the vasovagal reaction rate and an 11% decrease in the presyncope reaction rate for women, and a 21% reduction in the total vasovagal reaction rate and a 24% decrease in the presyncope reaction rate for men. A multivariate analysis showed that the reduction of the total reaction rate declined as EBV increased. The three interventions had no effect on the observed and reported fall rates. In sum, Blood Systems' interventions decreased the total reaction rate by 24% and the syncopal reaction rate by 22% but had no effect on the donor fall rate. The reduction in syncope rate after intervention is greater than that found by ARC, but the effects of intervention are otherwise consistent. In both studies, compliance with interventions was incomplete. Blood Systems reduced the proportion of donors with EBVs below 3500 mL by 96%. ARC did not report its reduction. In the ARC, compliance with using water and performing muscle tension was measured using a donor survey, which 11% of the 16- to 18-year-old donors completed. Fifty-four percent of the donors reported drinking all of the water, 28% reported drinking some of the water, and 18% reported not drinking water. Just 22% of the ARC donors reported doing leg lifts. Blood Systems did not document the use of water or muscle tension during the donation process and therefore could not report on the extent of their use. Some of Blood Systems' centers provided less than 500 mL of water to donors, and their staff were reluctant to educate donors about the prescribed muscle tension exercises. Both systems should be praised for their success in decreasing the presyncope vasovagal reaction rate by 21% to 24% and for adding knowledge on how deferrals for low EBV, water consumption, and muscle tension affect presyncope, syncope, and donor injury or fall rates. What more can be done? For each intervention, the relation between compliance and effectiveness should be determined. The use of water and muscle tension should be encouraged and documented. In the case of water, the volume drunk and the time between the end of the drink and the start of the phlebotomy should be recorded. The latter item is important because one of the explanations for water's effect is expansion of the stomach, which causes a sympathetic discharge and vasoconstriction in the extremities.18 Since half of the water leaves the stomach in 20 minutes, the effect of water ingestion is inversely related to the time from the drink and probably disappears after 45 minutes.13 The mechanism of action of water ingestion should be elucidated. It has been suggested that drinking water, which is hypotonic, stimulates osmoreceptors in the liver and portal vein and causes a sympathetic discharge.19-21 According to this mechanism, there would be benefit from a hypotonic water drink but not from fluids of greater osmolality such as juices, sodas, or energy drinks. For muscle tension, the techniques being used are too tedious and impractical for the blood donation setting and need to be simplified. Perhaps the frequency should be lowered, and the procedure should be started toward the end of phlebotomy. Also, donors should be given postdonation instructions that suggest a muscle tension action and advise the donor to lie down immediately upon becoming dizzy. Other interventions should be explored. A recent article suggested that a donor eat salt-laden foods before and after blood donation and drink additional isotonic fluids after the donation to increase plasma volume.22 About half of the salt content ingested will still be in the vascular system at 24 hours, and in theory, the increase in plasma volume could provide protection against delayed syncopal reactions. Several Asian countries collect 400-mL or smaller units, and a smaller blood collection volume would decrease the vasovagal reaction rate. However, collection of a subset of small-volume donations complicates manufacturing, distribution, and dosage. Even after interventions, young donors are at higher risk for vasovagal reactions.10 Excluding them would decrease the aggregate vasovagal reaction rate but unless they could be replaced, there would be a decrease in the blood supply. Interventions are thus part of a balance between an adequate blood supply and a lower reaction rate. In summary, the high proportion of blood donations by young donors stimulated activity to reduce vasovagal reaction rates. We have decreased the vasovagal reaction rate in young donors, but we can continue to reduce it further. Further reduction will require better compliance with established interventions and investigation of new measures, but our ability to totally eliminate these reactions is probably not unlimited. Therefore, we also need to strive for the best environment and procedures to improve safety in those who do have a syncopal reaction. None.