Power spectral analysis of blood pressure variability in traumatic quadriplegic humans

Abstract

A study was performed on seven traumatic neurologically complete quadriplegic (QP) males and seven age-matched healthy males (control) while they were at rest in the supine position in a climatic chamber (temperature 30 degrees C, relative humidity 60%). Arterial blood pressure waveforms were measured by a continuous noninvasive blood pressure-monitoring system based on arterial tonometry. Furthermore, the spontaneous beat-to-beat systolic blood pressure (SBP) variabilities of subjects were investigated by means of autoregressive power spectral analysis. As shown by earlier studies with an invasive (intra-arterial) blood pressure-monitoring system, in the control group there were two major spectral components: a high-frequency (HF) component [center frequency 0.27 +/- 0.02 (SE) Hz eq, power 0.9 +/- 0.2 mmHg2] and a low-frequency (LF) component (0.10 +/- 0.01 Hz eq, 5.2 +/- 1.4 mmHg2). On the contrary, in the QP group only the HF component was observed (0.28 +/- 0.03 Hz eq, 3.2 +/- 1.4 mmHg2). The results suggest that 1) in the QP subject the disappearance of the LF component in the SBP variability (i.e., the Mayer waves in humans) is presumably caused by the interruption of the spinal pathways linking supraspinal cardiovascular centers with the peripheral sympathetic outflow and 2) the cervical spinal sympathetic pathways may be instrumental in the genesis of the Mayer waves in humans.

Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury

“…LF BPV in the thoracic SCI group tended to be reduced compared with controls, although to a lesser extent than in the cervical SCI group. These results are similar to those of others (25,27,44). This probably reflects reduced sympathetic drive to the lower body in individuals with autonomically complete thoracic SCI.…”

“…LF BPV in supine and upright positions was reduced in the cervical SCI group, as reported previously (26,27,44). This probably reflects reduced sympathetic outflow to resistance vessels (2,12,46) due to interruption of descending sympathetic pathways (27), which is supported by the lower blood pressures in the cervical SCI group. LF BPV in the thoracic SCI group tended to be reduced compared with controls, although to a lesser extent than in the cervical SCI group.…”

“…Note increased LF phase shift (delay) in SCI subject (arrow). (19,29) but has been reported previously (5,20,27,28). The reduced HF power in thoracic SCI subjects suggests reduced vagal tone (33,46,51), which is supported by their higher heart rates.…”

Power spectral analysis of heart rate and blood pressure variability in lumbar epidural anaesthesia

“…9,1~ The high frequency component of blood pressure is mediated by a mechanical consequence of respiration, which may act directly on intrathoracic vessels or indirectly through changes in stroke volume and heart period. 9 In this study we compared the changes in heart rate and blood pressure variability when the level of block analgesia was below T 5 (high epidural anaesthesia group) or at Ti0 (low epidural anaesthesia group). The interaction between sympathetic and parasympathetic activity, using power spectral analysis based on the Fast Fourier transform (FFT), in the area of lumbar epidural anaesthesia was studied.…”

Effects of compression stockings on sympathetic activity and heart rate variability in individuals with spinal cord injury

“…3 As a consequence, sympathetic autonomic activity markers such as HRV or catecholamines will be markedly altered. [4][5][6][7][8][9][10][11] The spinal cord lesion leads to an interruption of pathways from the brain to the peripheral SNS, which results in pathological changes in sympathetic innervation depending on the anatomical distribution. 12,13 SNS dysfunction causes an inability to induce vasoconstriction in the legs and splanchnic area below the level of lesion, as well as a disruption of the catecholamine response.…”