title: Human autonomic responses to blood donation.
abstract: In order to characterize autonomic responses to acute volume loss, supine ECG, blood pressure (BP) and uncalibrated breathing signal (UBS) recordings were taken before and after blood donation in 48 healthy volunteers. Time and frequency domain parameters of RR interval (RRI), BP and UBS variability were determined. Baroreflex gain was calculated by the technique of the spontaneous sequences and cross-spectral analysis. The systolic (SAP), diastolic (DAP) and mean BP (MAP) increased after the blood withdrawal. The central frequency of breathing and mean heart rate did not change. RRI variability increased in low frequency band (LF), tended to decrease in high frequency band (HF). Systolic BP variability increased in both frequency bands, but was statistically significant only in the high frequency band. Diastolic BP power increased in both frequencies. From the different baroreflex gain estimates, up sequence BRS and HF alpha index decreased significantly. The phase angle between RRI and systolic blood pressure powers in LF band did not change (-58 +/- 24 degrees and -54 +/- 26 degrees ). In the high frequency range, the phase became more negative (-1 +/- 29 degrees and -17 +/- 32 degrees, p = 0.001). The withdrawal of 350-400 ml blood in 5 min resulted in sympathetic activation, which was reflected in increased systolic, diastolic and mean BP. The increased BP oscillation was a sensitive marker of the minor volume depletion. This was coupled by increased RRI oscillation via baroreflex mechanisms in the LF band. Changes in the RRI and BP oscillations in the HF band showed no similar coupling. That points to the fact that RRI oscillations in this band should not be explained entirely by baroreflex mechanisms. Vagal withdrawal was reflected in decreased root mean square of successive differences (RMSSD), decreased HF RRI power and decreased up sequence BRS.
authors.affiliation: University of Szeged, Faculty of Medicine, Cardiology Center, Medical Intensive Care Unit, Korányi fasor 7, Szeged 6720, Hungary. zollei@hotmail.com
authors.forename: Eva
authors.initials: E
authors.lastname: Zöllei
authors.forename: Dóra
authors.initials: D
authors.lastname: Paprika
authors.forename: Péter
authors.initials: P
authors.lastname: Makra
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Gingl
authors.forename: Klára
authors.initials: K
authors.lastname: Vezendi
authors.forename: László
authors.initials: L
authors.lastname: Rudas
mesh_terms: D000293:Adolescent; D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology; D001782:Blood Donors; D001794:Blood Pressure / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006470:Hemorrhage / Q000503:physiopathology*; D006801:Humans; D020896:Hypovolemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012143:Respiratory Physiological Phenomena; D013564:Sympathetic Nervous System / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology; D014666:Vasomotor System / Q000502:physiology