Mild hypovolemic stress alters autonomic modulation of heart rate.

Abstract

In response to changes in central venous volume, changes in vagal efferent cardiac outflow have been demonstrated in animals but not in humans. In this study, frequency domain analysis was used to quantify modulation of heart rate by respiration and blood pressure in normal human adults undergoing mild central hypovolemic stress induced by blood donation and postural change. In supine subjects, blood donation caused no change in mean heart rate, pulse pressure, or in the variance of heart rate or blood pressure. There were small decreases in mean and systolic blood pressures. A significant decrease in vagal modulation of heart rate was seen in the 0.12-0.5-Hz frequency band, as measured by the change in the relation of lung volume to heart rate in this frequency band (-4.49 beats per minute [bpm] per liter [I], p<0.001). Comparison of supine and tilt positions revealed marked changes in heart rate and blood pressure means and variances consistent with more pronounced decreases in intracardiac filling pressures and unloading of the arterial baroreceptors. A further progressive decrease in the vagal modulation of heart rate by lung volume was observed in the 0.12-0.5-Hz band, with a near-linear response of magnitude of respiratory sinus arrhythmia over a range of estimated central venous volume. Transfer function analysis can detect changes in autonomic response to mild degrees of central hypovolemia, which are insufficient to cause changes in mean heart rate or heart rate variance. This represents evidence for modulation of heart rate control by cardiopulmonary baroreceptors. A near-linear relation between magnitude of respiratory sinus arrhythmia and central venous volume suggests that this may have clinical relevance in patient monitoring. (Hypertension 1993;21:236-247) KEY WORDS • autonomic nervous system • pressoreceptors • hemorrhage • heart rate

Heart rate control and mechanical cardiopulmonary coupling to assess central volume: a systems analysis

“…First, although the presence of the Bainbridge reflex has been controversial in humans (3), one report has clearly demonstrated reflex tachycardia with volume loading in humans (17). Furthermore, Triedman et al (25) found that mild hypovolemia from a 10% blood donation significantly changed arterial baroreflex control of heart rate without changing either mean heart rate or arterial pressure, consistent with the findings of others during low levels of LBNP (8).…”

A Comparison of Real-Time Performance of Signal Processing Algorithms for Minimum Latency Detection of Hypovolemic States

“…Candidate spectral processing algorithms included Fast Fourier Transform (FFT) with BlackmanTukey estimation (BT) [6], auto regressive (AR) [7][8], and Wavelets processing using Haar and db10 wavelets [10].…”

Elevated HbA1c Levels Are Associated with the Blunted Autonomic Response Assessed by Heart Rate Variability during Blood Volume Reduction

“…HbA1c, hemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. (Triedman et al 1993;Kosowsky et al 2002;Haberthür et al 2003;Zöllei et al 2004). According to the five classes of hemorrhagic shock, the quantity of blood volume loss in the present study constitutes less than a class I hemorrhage (15% of the circulating blood volume) (American College of Surgeons Committee on Trauma 2012).…”

“…The autonomic nervous system, which mediates the baroreceptors (arterial and carotid sinus) and cardiopulmonary receptor, establishes a short-term regulatory system for maintaining cardiovascular stability. This mostly initial compensatory mechanism leads to cardiac vagal withdrawal and sympathetic activation immediately induced by blood volume reduction (Schadt and Ludbrook 1991;Triedman et al 1993;Furlan et al 2001). In our study, with the course of blood volume reduction, the HF component, as an index of cardiac vagal nerve activity, and the LF/HF ratio, as an index of sympathetic nerve activity, signifi cantly continued to decrease and increase from the pre-blood to post-blood donation stage in the HbA1c < 6.5% group.…”

“…3). Only a few previous studies have evaluated HRV during blood donation in humans (Triedman et al 1993;Zöllei et al 2004;Middleton et al 2008). These studies reported that due to blood loss (350-500 mL), the HF power and LF/HF ratio have a tendency to decrease (Triedman et al 1993;Zöllei et al 2004;Middleton et al 2008) and increase (Middleton et al 2008).…”