RESUMO
A digital system for bioimpedance and electrical impedance tomography (EIT) measurement controlled by an ATmega16 microcontroller was constructed in our laboratory. There are eight digital electrodes using AD5933 to measure the impedance of the targets, and the data is transmitted to the computer wirelessly through nRF24L01. The structure of the system, circuit design, system testing, vitro measurements of animals' tissues and electrical impedance tomography are introduced specifically in this paper. The experimental results showed that the system relative error was 0.42%, and the signal noise ratio was 76.3 dB. The system not only can be used to measure the impedance by any two electrodes within the frequency of 1-100 kHz in a sweep scanning, but also can reconstruct the images of EIT. The animal experiments showed that the data was valid and plots were fitting with Cole-Cole theory. The testing verified the feasibility and effectiveness of the system. The images reconstructed of a salt-water tank are satisfactory and match with the actual distribution of the tank. The system improves the effectiveness of the front-end measuring signal and the stability of the system greatly.
Assuntos
Animais , Impedância Elétrica , Eletrodos , Tomografia , MétodosRESUMO
Objective To investigate the analgesic effects of parecoxib sodium combined with patient controlled epidural analgesia (PCEA) after orthopedic subarachnoid block anesthesia surgery.Methods Two hundred patients undergone orthopedic subarachnoid block anesthesia surgery were randomly and equally divided into two groups:Group P (treated intravenously with 40 mg parecoxib sodium combined with PCEA at the end of operation) and Group C ( treated intravenously with 0.5 g tramadol combined with PCEA at the end of operation).The visual analog scale (VAS) was performed at 6,12,24,48 and 72 hours postoperatively in two groups.Meanwhile,the press frequency of analgesic pump,effective frequency,side effects and satisfaction degree were recorded. Results The VAS sore of Group P was lower than that of Group C at 6,12,24,48 and 72 hours postoperatively ( P ＜ 0.05 ).Group P showed a less number in aspects of the press frequency of analgesic pump,effective frequency,and side effects at 12 and 24 hours,but a higher satisfactory degree,compared with Group C (P ＜0.05). Conclusion Combined use of parecoxib sodium and PCEA can exert a better analgesic effect and have a low incidence rate of side effects following orthopedic subarachnoid block anesthesia.