Autonomic, endocrine, and psychological stress responses to different forms of blood draw.

These findings challenge the characterization of fingerstick as necessarily "less invasive" than venipuncture, as participant's stress responses to fingerstick were equivalent to (and for some measures greater than) their response to venipuncture. Heart rate variability response to fingerstick significantly predicted that individual's vasovagal-like responses to venipuncture, suggesting that measuring heart rate variability during pre-donation hemoglobin testing may identify donors at risk for adverse events during venipuncture.