Integrating-Types Biomedical Signal Communication System Combined Power Line and Radio Frequency Communication / 대한의료정보학회지

OBJECTIVES: In order to devise the combination module transmitting bio signal and signal data remotely, as defect of wirewireless combination module was complemented by designing a single combination of wireless module and power supply module, a single system was implemented. METHODS: Currently in case of wireless transmission, it had various problems causing by some factors such as buildings, obstruction, and entanglement of wires and so on. In order to overcome problems of wireless transmission, a single combination module design was researched, which transmits vital signal and sign data using basic electric line installed in the inner building or between others. Even though it was also possible of wireless communication and the internet, in case of a power supply without them, it could be possible to transfer data to underground or top ground in the inner building without any special communication line. RESULTS: Bio signal data was transmitted through a power supply line, a noise problem occurred would be solved by the designed noise filter. The filter showed that noise was cut off about more than 90%. It was also confirmed that the used ECG signals was stably received on transmission experiment. An internal PCB antenna could make the system be wireless communication without the disclosure of an antenna. CONCLUSIONS: In this study, in order to implement a useful system transmitting bio signal and data through wire and wireless management for combination design of wireless module and electrical line module, bio signal transmission system was implemented by design of noise break filter circuit to reduce power noise and PCB internal antenna design.

TThe Evaluation of Anesthesia Depth Using Detrended Fluctuation Analysis Parameters / 대한마취과학회지

BACKGROUND: We examined the use of DFA-Detrended fluctuation analysis-of heart rate variability during general anesthesia in order to assess the depth of anesthesia. METHODS: In this study, we observed changes in alpha1, the short range scaling exponent, in alpha2, the long range scaling exponent, and in the alpha2/alpha 1 ratio during enflurane anesthesia. We monitored 7 stages during general anesthesia, i.e., 1) preoperation (awake state), 2) during induction, 3) after induction, 4) during maintenance, 5) before extubation, 6) after extubation, and 7) postoperation (Next day). RESULTS: The alpha 2/alpha 1 ratio increased during the induction and extubation state compared to preoperation (awake state). This may be related to increased sympathetic activity due to stimulation of the autonomic nervous system. In the postoperation (awakened state), the ratio returned to the preoperation value (awake state). These results are similar to low frequency (LF), high frequency (HF) and LF/HF ratio values which reflect activity of autonomic nervous system. CONCLUSIONS: Detrended fluctuation analysis parameters, especially the alpha 2/alpha 1 ratio, would be used for monitoring the depth of anesthesia. Also these parameters are useful indexes with the LF/HF ratio for the evaluation of sympathetic activity during general anesthesia.

Monitoring System during Enflurane Anesthesia Using Heart Rate Variability / 대한마취과학회지

BACKGROUND:We performed spectral analysis and determined the 1/f noise of heart rate variability during enflurane anaesthesia in order to assess the effect of the activity of the autonomic nervous system. METHODS: Data were acquired from 15 patients (ASA I-II) who received gynecological surgery under general anesthesia using enflurane, nitrous oxide and oxygen. We analyzed the spectral components of heart rate variability (HRV) according to the following five periods: 1) before premedication, 2) after induction, 3) during skin incision, 4) during recovery, and 5) after surgery. For each power spectrum the density and frequency components were identified as follows: (1) low frequency (LF) component (0.04-0.15 Hz) was associated with parasympathetic and sympathetic tone, and was affected by body temperature, the renin-angiotensin system, baroreceptor and vasomotor sympathetic modulation, (2) high frequency (HF) component (0.15-0.5 Hz) was mediated parasympathetic tone and reflected the mechanical influence of the ventilation. In addition the LF/HF ratio, which reflected cardiac sympathovagal balance was monitored. RESULTS: The LF/HF ratio, which reflects the balance of the autonomic nervous system increased remarkably during skin incision and recovery. Also, the beta index, which is related to body activity decreased during skin incision and recovery. CONCLUSIONS: Increased LF/HF was found to be caused by mechanical stimulation, which reflects autonomic nervous system balance, and the beta index was useful for the assessment of body activity.

The Study of EEG Spectrum Analysis as a Method of Monitoring the Depth of Anesthesia / 대한마취과학회지

BACKGROUND: Monitoring the "depth of anesthesia" is an ongoing problem. To identify a useful parameter for determining the depth of anesthesia with enflurane, EEG data was obtained using a Physiolab 800. METHODS: Variations in EEG signals were measured and analyzed by the stage of anesthesia. EEG data was obtained from 15 patients during general anesthesia with enflurane. The EEG signal was acquired and analyzed in 5 steps (one day before anesthesia, during induction, during skin incision, at end of anesthesia, and one day after anesthesia). Fp1 electrode and the EEG data mainly from the forehead were used to determine the depth of anesthesia using EEG characteristics during enflurane anesthesia. All data were preprocessed by filtering, baseline correction and using the linear detrend method to reliable analyze of sample data in the surgical environment. Data obtained were transformed to frequency and power spectrum analysis was performed. RESULTS: alpha, beta, delta and theta waves were detected by frequency area separation and the trend of each wave was observed during each anesthesia stage. EEG data was slowed down and the theta wave ratio increased as the depth of anesthesia increased. Accordingly, spectral edge frequency (SEF) and median frequency (MF) were used as parameters to determine the depth of anesthesia. The frequencies of SEF and MF decreased during anesthesia and returned to the preanesthetic level after the cessation of anesthesia. CONCLUSIONS: Our results suggest that SEF and MF can contribute as useful parameters to determine the depth of anesthesia. Anesthetics not only affect the central nervous system, but also affect the autonomic nervous system. If the autonomic nervous system signals such as heart rate variability are taken into account, more reliable evaluations would be possible.