Application Research Of BIS Monitoring System For Assessing The Depth Of Sedation In ICU Patients

Objective:Serious illness patients who were received large surgical operations,most of them will be treated by a series of traumatic occlusions and treatments.Such as tracheal intubations,mechanical ventilations,suctions and AtV punctures et al,many of the critical patients with high risk factors for sleep deprivations and disturbance of orientation force,since that they will be created anxiety,restlessness and delirium mental illnesses.The Bispectral Index(BIS)is a processed EEG parameter that measures the hypnotic effects of anesthetic and sedation agents on the brain.It is derived from measurements of the frequency,amplitude and coherence of the EEG which have been shown statistically to relate to consciousness and unconsciousness. Represented as a single number--ranging from 100 for wide awake to 0 in the absence of brain activity--the BIS is a continuous measure of the patient's current hypnotic state,baseline information is not required for monitoring.Nowadays it is widely used due to its reliability and applicability.Nevertheless some doubts still exist regarding its usefulness in ICU.At this regard literature data are not uniform and many doubts still exist on the real clinical validity,reliability and applicability of BIS monitoring in ICU patietnts.In order to verify the clinical validity,reliability and applicability of BIS as ICU sedation monitoring tool,we performed the present study in which a correlation between BIS values and clinical scores was searched.Materials and methods: After informed consent,60 consecutive patients were enrolled in the study.They were admitted in ICU for postoperative monitoring after major abdominal or vascular surgery and required sedation for mechanical ventilation until hemodynamic,respiratory and metabolic sterilization was achieved.Patients with known or suspected intolerance to those aged less than 18 years and who were with serious head trauma,hepatic,renal function damage were excluded.Exclude patients with loading dose and(or)continuous infusion of propofol were given in 2 hours and whose sedation had been established with agent other than propofol for more than 24 hours and patients received long-lasting local or regional anesthetic blocks,patients with long-term usage of opioid drug were also excluded.On arriving in ICU patients after that ventilator was used to assist respiration/sinchronized intermittent mandatory ventilation(SIMV) mode of ventilation was used.Duration of sedation and time between discontinuation of sedation and extubation were measured.BIS monitoring was conducted by Aspect Medical Systems which was produced in the USA including Aspect medical systems A-2000,once-time sensor and infusion of all drugs were performed by Base Primea Orechestra drug infusion workstation.Heart rate,mean blood pressure and pulsoximetry monitoring were performed by HP invent firm.The propofol provided from AstraZeneca in Italy,batch number FG538;Midazolam was taken by Nhna pharam corporation in CHINA,batch number 20080626;The Remifentanil offered by YiChang medicine limited company of CHINA,batch number 080511.All patients had been randomly(close envelope)assigned to three groups, submitted to general sedation and with target-controlled infusion(TCI) infusion of remifantnil(0.2-0.8)ng/ml was associated to control postoperative pain.Patients of group A(n=20) were sedated with TCI propofol,starting the infusion at 0.5μg/ml.Target blood drug concentration of group A was set the range of (0.5-2.0)μg/ml to maintain target sedation depth;The currently propofol TCI common pharmacokinetic models Marsh model suit for the age below 55 years old,and above 55 years old of patients choose the model of Schinder.Patients of group B(n=20)were sedated with propofol by continuous infusion of propofol by micro-pump,starting the infusion at 0.5mg/kg/h.Patients in group B depth by intravenous continuing infusion at the speed in the range of(0.5-2)mg/kg/h,and get the 0.5mg/kg to loading dose;The lasted group was group C(n=20) which the starting infusion speed was at 0.01mg/kg/h and using midazolam by continuous infusion.First time use midazolam loading dose by(2-3)mg.The patients in group C was continuing the same degree about the depth of sedation by the speeds at range of(0.02-0.05)mg/kg/h.In 3 groups,the sedation depth were maintained at the same sedation Ramsay Scale in the range of 2-5 and BIS index number within 60-80.About Ramsay Scale(Level 6 of Ramsay scale:1-sober,anxious or restless or both;2-sober, cooperative,orientated and tranquil;3-sober,responding to commands;4-sleep, brisk response to stimulus such as percus on glabellum or loud auditory stimulus; 5-sleep,sluggish response to stimulus;6-sleep,no response to stimulus) was chosen as target of sedation.Ramsay score was assessed every 1 hour and corresponding BIS index numbers if the patients wanted to sucking sputum we were record the Tracheal Suctioning Score(TSS) before sputum suction which was including 5 levels about the scale(Table 1)If we got TSS 1 sober by that sedation state,we plused the blood drug level to A group to(0.2-0.5)μg/ml;B group was intravenous continuing infused by 0.5mg/kg;Group C was took 0.01mg/kg by given in one time,we will set bake after to do that.In case of hemodynamic instability(a reduction of more than 30%of base values of mean blood pressure,heart rate and/or pulsoximetry)drugs doses were decreased (steps of propofol A group 0.5μg/ml and 0.5mg/kg of B group or midazolam for C group 0.01mg/kg).All data in the form of(?)+s were analyzed by SPSS13.0.Three group of patients general state of health,total sedation times,recovery time,dose of remfentanil were analyzed by One-factor ANOVA.The dose of two groups which used propofol use Independent-Samples T Test.Adverse events compared 3 groups we used Chi-square distribution.Analyzering the 3 groups of MBP,HR,SpO₂ at different time used repeated measurement.At sedation process we assembled the Ramsay scale,TSS score and corresponding BIS index numbers.On the one hand,correlation between BIS values and Ramsay scores,and on other hand,test the TSS score relationship with BIS index numbers,were searched by using Spearman test to obtain an "r" index ranging between 0and 1,being 1 the best correlation.Ramsay scores were compared with the average of BIS values obtained in the 30s before and the 30s after the stimulus application.To seek when the Ramsay scores got 2-5 and BIS took 80-60 for discriminate the sedation insufficient and oversedation.Compute sensitivity and specificity of BIS.To evaluate the sensitivity and specificity of sedation depth based on ROC curve and BIS.Work out critical value of BIS under appropriate sedative degree.Setp＜0.05 as the significant level.Results:1.There were no significant diferences among the three groups with respect to age,gender,weight or severity of diseases(APACHEâ…¡Scale),(P＞0.05).2.In total sedation times and dose of remifentanil within 3 groups and between group A& B the dose of propofol there were no significant differences.(P＞0.05)3.For compared 3 groups the recovery time got the P=0.003,had significant difference,(P＜0.05).We had got A group recovery time was(9.00±2.38)min,B group (10.35±2.06) min and C group(15.35±5.35) min.So we compared the A & C group and got the P=0.000,B & C group P=0.000.Furthermore compared between group A and B for recovery time P=0.239,there were no differences(P＞0.05).4.We got the Ramsay scores anad TSS scores respectively were 944 and 170 for corresponding BIS index numbers.Through the test Spearman corresponding displayed,BIS index numbers and Ramsay score(r=-0.852,P＜0.01)and TSS score(r =-0.752,P＜0.01),there had significant difference.5.Compute sensitivity and specificity of BIS.To evaluate the sensitivity and specificity of sedation depth based on ROC curve and BIS.Work out critical value of BIS under appropriate sedative degree.BIS is positive relative to Ramsay score and TSS score,when the Ramsay score is 2-5points and TSS score is 2-4 points,the corresponding critical value of BIS is 58.5-82.5.6.No significant difference was found among the groups concerning scales of adverse events in 3 groups.7.There were no significant differences in HR,MBP,SpO₂ among 3 groups,at T1,T2,T3,T4 across groups(P＞0.05).Compared among 3 groups,no significant differences in MBP,HR,SpO₂(P＞0.05);But there were significant differences between group A and group C,HR were founded at T1 and T4 points(P＜0.05).It means that HR in two groups at T1 and T4 were increasing tendency.Conclusions:1.BIS monitoring has good correlation with Ramsay and TSS scores.It can simultaneously and objectively monitor sedative depth of mechanically ventilated patients,which can show its value of BIS is 58.5-82.5.It has certain clinical diagnosis value for using in the ICU.2.Compared with 3 groups,there are no significant differences in HR,MBP,SpO₂ and adverse events,so we can have a conclusion that choosing a right sedation drug for patients in short time assessment the patients situations. 3.A group and B group by using the total dose of propofol there have no significant differences,but compared the recover time among this 3 group,that A group and B group will be shorter than C group.That can tell us propofol had a great affetion during short-time sedation in 24 h.