Modulation of cardiac autonomic tone in non-hypotensive hypovolemia during blood donation

Abstract

Non-hypotensive hypovolemia, observed during mild haemorrhage or blood donation leads to reflex readjustment of the cardiac autonomic tone. In the present study, the cardiac autonomic tone was quantified using heart rate and blood pressure variability during and after non-hypotensive hypovolemia of blood donation. 86 voluntary healthy male blood donors were recruited for the study (age 35 ± 9 years; weight 78 ± 12 kg; height 174 ± 6 cms). Continuous lead II ECG and beat-to-beat blood pressure was recorded before, during and after blood donation followed by offline time and frequency domain analysis of HRV and BPV. The overall heart rate variability (SDNN and total power) did not change during or after blood donation. However, there was a decrease in indices that represent the parasympathetic component (pNN50 %, SDSD and HF) while an increase was observed in sympathetic component (LF) along with an increase in sympathovagal balance (LF:HF ratio) during blood donation. These changes were sustained for the period immediately following blood donation. No fall of blood pressure was observed during the period of study. The blood pressure variability showed an increase in the SDNN, CoV and RMSSD time domain measures in the post donation period. These results suggest that mild hypovolemia produced by blood donation is non-hypotensive but is associated with significant changes in the autonomic tone. The increased blood pressure variability and heart rate changes that are seen only in the later part of donation period could be because of the progressive hypovolemia associated parasympathetic withdrawal and sympathetic activation that manifest during the course of blood donation.

Physiological stress response patterns during a blood donation

“…The stress response was mainly evidenced by an increase in systolic blood pressure towards needle insertion and a decrease thereafter. This response pattern is mainly in line with the literature, showing an overall decrease from pre‐ to post‐donation values, with a large decrease during the actual phlebotomy . As the present study is the only one to date that assesses the entire donation visit among different donor groups, this provided information on the different stress measures further in advance of the phlebotomy and for a longer period thereafter.…”

“…Heart rate is reported to decrease from pre‐ to post‐donation , to be stable , or to increase . Concerning HRV, studies have reported no change in overall HRV , a decrease in the parasympathetic HRV component , and an increase in the sympathetic HRV component . However, a decrease in the sympathetic component from pre‐ to post‐donation was also reported .…”

“…Studies investigating physiological stress responses in a blood donation setting have reported conflicting evidence. For example, blood pressure is reported to be stable , to decrease or to increase . Heart rate is reported to decrease from pre‐ to post‐donation , to be stable , or to increase .…”

“…For example, blood pressure is reported to be stable , to decrease or to increase . Heart rate is reported to decrease from pre‐ to post‐donation , to be stable , or to increase . Concerning HRV, studies have reported no change in overall HRV , a decrease in the parasympathetic HRV component , and an increase in the sympathetic HRV component .…”

“…Importantly, most of the studies thus far assessed physiological stress measures at only two moments during the donation procedure, that is before and after phlebotomy . Two studies, that performed a more detailed analysis of a blood donation procedure, indicated a non‐linear responses in HRV parameters : data from the study by Middleton et al . indicate a quadratic effect in the low‐frequency (LF) domain, levels decreasing from pre‐ to post‐phlebotomy, and peaking during the phlebotomy, and a cubic effect in the high‐frequency (HF) domain, overall decreasing from pre‐ to post‐phlebotomy with highest levels at the first part of the phlebotomy and lowest levels at the second part; data from Yadav et al .…”