Soo Young Ye

Evaluation of arterial compliance on pulse transit time using photoplethysmography

Pulse wave velocity has been widely used as an index of arterial distensibility. Peripheral pulse transit time (PTT) is inversely related to pulse wave velocity. The aim of this study was to evaluate the validity of PTT on the monitoring of arterial distensibility. We evaluated the accuracy of computerized measurement of peripheral PTT using an algorithm based on the time interval between the peak of R wave of ECG and maximal slope point in pulse. A experimental results were presented as a graph using spline interpolation. Application software was implemented in C++ as a window-based program. The increase of heart rate and pulse transit time reflect the hemodynamics changes by skin temperature. It is of great interest to evaluate in large populations the therapeutic and epidemiological applications of an arterial parameter as evaluated by peripheral PTT.

Detrended Fluctuation Analysis of EEG on a Depth of Anestheisa

Abstract The DFA(detrended fluctuation analysis) which is included the correlation property of the EEG is used to analysis the depth of anesthesia. We studied ASA I or II adult patients supported by the society of anesthesiologists. Patients with history of dementia and neurological disorder are excluded. Average age is 48.9 ± 10.9 old, average weight is 57.1 ± 8.2 kg and average hight is 158 ± 6.6cm of the patients under the operation. Anesthesia medicine is Sevoflurane and the stages of anesthesia are 6 stages, that is pre-operation, induction, right after induction, stop the medicine and post-operation. Among the scaling exponent , , , we know that ,  were well appeared to discriminate pre-operation, induction, right after induction, stop the medicine and post-operation. So we confirmed that the parameters is useful to the depth of anesthesia. Key Words : EEG, depth of anesthesia, DFA(detrended fluctuation analysis) 본 논문은 과학재단 특정기초 연구과제(R01-2007-000-20260-0) 의해 연구되었음.

The Measurement of Anesthesia Depth Using Biomedical Signal during General Anesthesia

The measurement of anesthetic depth is necessary in anesthesiology. NN10 is very simple method among the RR intervals analysis methods. NN10 parameter means the numbers of above the 10 ms intervals of the normal to normal RR intervals. Bispectrum analysis is defined as 2D FFT. EEG signal reflected the non-linear peristalsis phenomena according to the change brain function. After analyzing the bispectrum of the 2 dimension, the most significant power spectrum density peaks appeared abundantly at the specific area in awakening and anesthesia state. These points are utilized to create the new index since many peaks appeared at the specific area in the frequency coordinate. The measured range of an index was 0-100. An index is 20-50 at an anesthesia, while the index is 90-60 at the awake.In this paper, the relation between NN10 parameter using ECG and bisepctrum index using EEG is observed to estimate the depth of anesthesia during anesthesia and then we estimated the utility of the anesthetic.

Evaluation of the heart rate variability using the HRV analysis during general anesthesia

We examined the spectral analysis and 1/f noise of heart rate variability during enflurane anesthesia in order to assess the effect of activity of the autonomic nervous system. Data were acquired from 15 patients (ASA I-II) who got the gynecological surgery under general anesthesia using enflurane, nitrous oxide and oxygen. We have analyzed the spectral components of HRV according to the following five periods: 1) before premedication (S/sub pre/) 2) after induction (S/sub indu/) 3) skin incision (S/sub inci/) 4) recovery (S/sub awake/) 5) after surgery (S/sub post/). For each power spectrum density, the frequency components were identified as follows: (1) LF component (0.04-0.15 Hz) is associated with parasympathetic and sympathetic tone effected by body temperature, rennin-angiotensin system, baroreceptor and vasomotor sympathetic modulation, (2) HF component (0.15-0.5 Hz) mediated parasympathetic tone and reflecting mechanical influence of ventilation. In addition the LF/HF ratio reflecting the cardiac sympathovagal balance was monitored. The LF/HF ratio that reflects the balance of the autonomic nervous system increased remarkably during skin incision and recovery. Also, the index that shows the body activity decreased during skin incision and recovery. The increase of LF/HF was caused by mechanical stimulation, which reflects the autonomous nervous system balance. The index was useful for assessment of the body activity.

Monitoring of the EEG using the bispectrum analysis on the anesthetic depth

In this study, a distribute characteristics on the bispectral coupling of EEG were observed according to depth of anesthesia using bispectrum analysis method in a type of nonlinear signal processing. 25 patients of the general anesthesia were studied. In the preprocess, base line correction and linear detrend was used. In awakening state of patient in pre-operation and post operation, appearance rate of bispectral coupling was observed that a strong appearance rate was represented in major frequency zone such as (15,15) Hz but weak appearance rate investigated in the other minor frequency zone. During the anesthesia of patient, a strong appearance rate revealed the low frequency range below (10, 10) Hz and a weak appearance rate viewed in the other frequency range. Also the result was compared with the delta ratio and spectrum edge frequency (SEF). Delta ratio shows significant lower values at induction (3.60-0.98) and maintenance (5.0-4.74) of anesthesia than preoperation (10.30-2.44) and postoperation (13.03-2.29) (P<0.05). These result was consistent with a trend of delta ratio that the index of evaluation for depth of anesthesia known as a reflex of the conscious level of patients during anesthesia. While these results were not consistent with the analysis result of SEF that the index of evaluation for suppression level of patients during recovery stage of anesthesia. SEF shows lower values at maintenance (17.00-1.22) and postoperation (12.20-1.53) than preoperation (22.50-1.75) and induction (22.40-1.18) of anesthesia (P<0.05). The analysis method of bispectrum was useful information about the index of evaluation according to the level of unconsciousness and suppression among other evaluation factor on depth of anesthesia.