| Many clinical signs which indicated the anesthesia depth disappeared with the muscle relaxants universally used in the modern clinical anesthesia. Intraoperative awareness and memory sometimes occurred. That made anesthesiologists puzzled. Some researches indicated that patients who experienced intraoperative awareness in general anesthesia usually scared that they would remember intraoperative events and feel pain. The experience of intraoperative awareness made some patients gradually develop into post-traumatic stress disorder (PTSD). The incidence of intraoperative awareness was very low. As many as 1 or 2 in every 1000 patients who received general anesthesia experienced this outcome in western countries. Some small sample study in china found the incidence of intraoperative awareness was higher (2%~6%).In the December of 2005, the Task Force on Intraoperative Awareness, established by the American Society of Anesthesiologists, released a"Practice Advisory for Intraoperative Awareness and Brain Function Monitoring."They emphasized the application of many monitoring methods including electroencephalogram (EEG), bispectral index (BIS), evoked potential (EP), Entropy and so on. Up to now, just bispectral index passed the multicentric clinical verification. Monitoring bispectral index (BIS) during the operation in some people could depress the incidence of intraoperative awareness about 77~80%. But relative studies had some defects, such as control group (CG) lacked the data of bispectral or the study was not a prospective random double blind study. Our study was a prospective random double blind study. At the same time, we monitored the control group (CG) using of bispectral index. The aims of our study were to identify the incidence of the two groups and to find the function of BIS.We adjusted the depth of anesthesia according to the BIS in experimental group (EG) and according to the experience of anesthesiologist in control group (CG). Make sure that BIS was below 60 during the operation in EG. No sedation or hypnosis drugs before coming into operation room. Anesthesia induction: midazolam 1-2 mg, propofol 1-2.5 mg/kg, analgesia and muscle relaxant drugs have no specific regulations. Maintenance of anesthesia: propofol 4-12 mg.kg-1. h-1 and no inhalation narcortics or midazolam. Make signs at the time of anesthesia induction, operation beginning, operation ending, anesthesia withdrawal, palinesthesia. Patients were interviewed twice during 24 h and 96 h postoperatively to determine intraoperative awareness. The structured interview questions were: (l) What was the last thing you remembered before you went to sleep? (2) What was the first thing you remembered when you woke up? (3) Could you remember anything between these two periods? (4) Did you dream during your operation? (5) What was the worst thing about your operation? Make diagnosis about intraoperation awareness by the following standards: A. Without awareness: The patient could not remember anything during operation, or the things what the patient described took place before slept or after operation. B. Suspected awareness: The patient dreamed during operation, although the patient could not describe the dream obviously, it might be related with the operation, or the patient had vague memory to the operation. C. Awareness: If the patient could describe the operation, it could be judged the things what the patient described took place during operation. If the patient could remember the tings during operation, asked the content of awareness advanced, communicated with the doctor of anesthesia, confirmed the patient's dream. D. If any time we considered it awareness, this case was an intraoperative awareness case. If we considered it suspected awareness just one time, this case was a suspected awareness case. We recorded basic information about patients, especially the patients who were suspected awareness cases or awareness cases. Compare the two sets with the incidence of the intraoperative awareness. Delt with the results with SPSS15.0 software. Analyzed measurement data with x±S and interclass difference with independent sampler t test; Delt with count data using x2 test; P<0.05 for statistical significance. Compared the two groups to see that whether there were differences in the basic and intraoperative situations and whether the incidence of intraoperative awareness between the two groups was different. And then evaluated the effects of BIS.The result revealed that there was no case of intraoperative awareness in EG and there were no cases of intraoperative awareness, but two cases of suspected awareness. The incidence of intraoperative awareness between the two groups was not different (P>0.05). There was significant difference in the incidence of suspected awareness. The sex,age,weight,class of ASA,anesthetic method,operation time,preanesthetic medication,circulating state of the patients did not have relation with awareness (P>0.05). Base figure of BIS was 95±3.31 in EG and 94±4.18 in CG, there was no difference (P>0.05). BIS was 27.75±8.90 at the end of induction in EG and 28.90±10.51 in CG, there was no difference (P>0.05). The average of BIS was 45.21±6.94 at the maintenance of anesthesia in EG and 52.79±8.87 in CG, there was significant difference (P<0.05). At the end of anesthesia BIS was 51.69±11.09 in EG and 57.87±10.27 in CG, there was significant difference (P<0.05). At the end of operation BIS was 55.97±10.49 in EG and 63.67±9.91in CG, there was significant difference (P<0.05). When patients had consciousness BIS was 75.09±5.50 in EG and 5.38±5.61 in CG, there was no significant difference (P>0.05). BIS was 79.50±4.31 in EG and 79.70±4.20 in CG when extubating, there was no significant difference (P>0.05). There was no significant difference in the incidence of intraoperative awareness between two groups. But there was significant difference in the incidence of suspected awareness. BIS figure was higher in CG.So we think that we may avoid light anesthesia and depress the incidence of intraoperative awareness by monitoring BIS. BIS may have some functions in preventing intraoperative awareness.
|
PDF Full Text Request