Phlebotomy duration and vasovagal reaction rate

Long phlebotomy duration in whole blood donors has been associated with increased vasovagal reaction rate. Here, we wanted to re-examine this relationship.

Complete whole blood donations in the years 2021 and 2024 with a vasovagal reaction were matched to the previous whole blood donation in the same donor, provided the previous whole blood donation was complete and no vasovagal reaction was recorded. Subsequently, the phlebotomy duration was compared between the donations with and without a vasovagal reaction. In a subset of donors with 4 min or more difference in phlebotomy duration, the vasovagal reaction rate was compared between donations with longer and shorter durations. In addition, we performed multivariable logistic regression on the vasovagal reaction rate for all complete blood donations using phlebotomy duration as one of the predictors.

We identified 6838 donors (4778 female, 2060 male) where a donation with and without a vasovagal reaction could be matched. The mean phlebotomy duration with a vasovagal reaction (7.90 min) was not different from the previous donation without (7.93 min). Furthermore, the vasovagal reaction rate was not higher in donations with longer phlebotomy duration. In contrast, in the multivariable logistic regression, longer phlebotomy duration was associated with an increased vasovagal reaction rate.

Within the same donor, phlebotomy durations are not longer in donations with a vasovagal reaction, and differences in phlebotomy durations between donations do not result in a different vasovagal reaction rate. Thus, longer phlebotomy durations do not directly cause an increased vasovagal reaction rate.