[雙語翻譯]--生物醫(yī)學(xué)工程外文翻譯--使用生物組織阻抗傅里葉分析（英文）

1、 Assessment of vasomotor oscillations with Fourier analysis of biological tissue impedance A Nesterov, I Gavrilov, L Selector, I Mudraya and S Revenko1 National Cardiology Center, Research Institute of Urology, Moscow

2、, Russia E-mail: s_revenko@mail.ru Abstract. Fourier analysis revealed a number of periodicities in small variations of bioimpedance of human finger including the major spectrum peaks at the frequencies of heart beats

3、, respiration, and Mayer wave (0.1 Hz). These periodic variations of bioimpedance were detected under the normal conditions and during blood flow arrest in the hand by a pneumatic cuff placed on the arm. They are expla

4、ined by periodic variations in systemic blood pressure and by oscillations of regional vascular tone resulted from neural vasomotor control. During normal blood flow, the greatest variations in bioimpedance were observ

5、ed at the heart rate, and their amplitude surpassed by an order of magnitude the amplitudes of respiratory oscillations and Mayer wave. In contrast, during blood arrest, the largest amplitude of rhythmical changes of

6、the impedance characterized the oscillations at respiration rate, while the amplitude of oscillations at the heart rate was the smallest. During normal respiration and circulation, two side cardiac peaks were revealed

7、in bioimpedance amplitude spectrum which disappeared during respiration arrest and thought to reflect the amplitude respiratory modulation of the cardiac output via sympathetic influences. During normal breathing, the

8、second and the third harmonics of the cardiac spectrum peak were split reflecting frequency respiratory modulation of the heart rate by parasympathetic influences. The results favour applicability of Fourier analysis

9、of bioimpedance variations in assessment of regional neural influences and neurogenic modulation of cardiac activity. 1. Introduction A spectacular progress in microelectronics resulted in appearance of low-noise chips

10、 and powerful computers which made it possible to measure and analyze small bioimpedance variations with a laboratory-made high-resolution impedance converter and original software. We analyzed bioimpedance variations

11、 in human finger with Fourier transform in the frequency band of 0.08-15.0 Hz under the normal conditions and during circulation arrest in the arm optionally combined with expiratory delay for 40 sec. The aim was to as

12、sess the neurogenic contribution to bioimpedance variations, which probably result from vasomotor activity of sympathetic nerve system. 2. Methods Bioimpedance was measured with original impedance converter based on sy

13、nchronous detection principle resulting in total (“basic”) real part of impedance in the frequency band of 0–15 Hz (R=) and the variable component of this real part in the frequency band of 0.08–15 Hz (R~). The measuri

14、ng 1 To whom any correspondence should be addressed. International Conference on Electrical Bioimpedance IOP PublishingJournal of Physics: Conference Series 224 (2010) 012125 doi:10.1088/1742-6596/224/1/012125c ? 2010 I

15、OP Publishing Ltd 1Figure 2. Amplitude spectrum of bioimpedance variations in human finger over broad frequency range with Mayer’s peak (1), respiratory peak (2), four cardiac harmonics (3 to 3’’’’), and the side pe

16、aks (3L, 3R, etc). Note the break in ordinate. Another important observation is splitting of higher harmonics of the cardiac peak observed under normal conditions in some cases (figure 3, a). Such splitting was far les

17、s pronounced under respiration delay (figure 3, b). Splitting of a peak can be explained by frequency modulation of basic oscillatory process with another process going on at a smaller rate; in this case, splitting can

18、 result from vagal modulation of the heart rate at the respiration frequency. In this experiment, the oscillations were cut off below 0.3 Hz, so no Mayer peak is seen in figure 3. Figure 3. The respiratory (2) and sid

19、e cardiac peaks (L and R) are observed under normal conditions (a) but disappeared during expiratory delay (b). In order to assess the changes in bioimpedance of non-pulsatile (non-cardiac) origin, we compared the bioi

20、mpedance spectra during normal circulation (figure 4, a) and during blood arrest in the arms (figure 4, b). Circulation arrest did not eliminate oscillations of bioimpedance although diminished their amplitude (figure

21、4, b). Under these conditions, the periodic bioimpedance oscillations could be produced either by neurogenic vasomotor influences or by spontaneous vasomotions. The latter are characterized with a broad range at the lo

22、w frequencies of 0.008 – 0.11 Hz [4]. The narrow shape of all peaks in Fig. 4 does not favour the hypothesis of spontaneous nature of the corresponding bioimpedance oscillations. Thus, all the peaks in figure 4, b are

23、probably neurogenic and vasomotor in nature. Arrest of circulation dramatically reduced the cardiac peak, which is a trivial consequence of the fact that during normal circulation the major variations in bioimpedance

24、 are produced by pumping action of the heart. Surprisingly, the respiratory peak 2 and Mayer’s peak 1 decreased by no more than 2-fold. It means that during normal circulation, the heart and systemic blood pressure are

25、 not the major players who control these rhythmic variations of bioimpedance. During circulation arrest, the International Conference on Electrical Bioimpedance IOP PublishingJournal of Physics: Conference Series 224 (2