Bispectral Score Research Articles

The prediction of postoperative delirium with the preoperative bispectral index in older aged patients: a cohort study

BackgroundPostoperative delirium (POD) is the most common postoperative complication in elderly patients, especially in older aged patients (aged 75 years or over). The development of electroencephalography analysis could provide indicators for early detection, intervention, and evaluation. If there are pathophysiological changes in the brain, the BIS value will also change accordingly. In this study, we investigated the predictive value of the preoperative bispectral (BIS) index in POD for patients aged over 75 years.MethodsIn this prospective study, patients (≥ 75 years) undergoing elective non-neurosurgery and non-cardiac surgery under general anesthesia were included (n = 308). Informed consent was obtained from all involved patients. Before the operation and during the first 5 postoperative days, delirium was assessed with the confusion assessment method by trained researchers twice every day. Thereafter, the preoperative bedside BIS of each patient was dynamically acquired by the BIS VISTA monitoring system and the BIS monitoring of electrodes. A series of evaluation scales were assessed before and after surgery. A preoperative predictive score was generated according to the results of multivariable logistic regression. The receiver operating characteristic curves were drawn and the area under the curves was estimated to evaluate the perioperative diagnostic values of BIS and preoperative predictive score for POD. The specificity, sensitivity, positive predictive value (PPV), and negative predictive (NPV) value were calculated.ResultsDelirium occurred in 50 of 308 (16.2%) patients. The median BIS of delirious patients was 86.7 (interquartile range [IQR] 80.0–94.0), lower than that of the non-delirious 91.9 (IQR 89.7–95.4, P < 0.001). According to the ROC curve of the BIS index, the optimal cut-off value was 84, with a sensitivity of 48%, specificity of 87%, PPV 43%, NPV 89% for forecasting POD and the area under curves was 0.67. While integrating BIS, mini-mental state examination, anemia, activities of daily living, and blood urea nitrogen, the model had a sensitivity of 78%, specificity of 74%, PPV of 0.37%, and NPV of 95% for forecasting POD, and the area under curves was 0.83.ConclusionsPreoperative bedside BIS in delirium patients was lower than that in non-delirium patients when undergoing non-neurosurgery and non-cardiac surgery in patients aged over 75. The model of integrating BIS, mini-mental state examination, anemia, activities of daily living, and blood urea nitrogen is a promising tool for predicting postoperative delirium in patients aged over 75.

Comparison of Bispectral Index Monitor Data Between Standard Frontal-Temporal Position and Alternative Nasal Dorsum Position in the Intensive Care Unit: A Pilot Study.

BACKGROUND: The Bispectral (BIS) monitor is a validated, noninvasive monitor placed over the forehead to titrate sedation in patients under general anesthesia in the operating room. In the neurocritical care unit, there is limited room on the forehead because of incisions, injuries, and other monitoring devices. This is a pilot study to determine whether a BIS nasal montage correlates to the standard frontal-temporal data in this patient population. METHODS: This prospective nonandomized pilot study enrolled 10 critically ill, intubated, and sedated adult patients admitted to the neurocritical care unit. Each patient had a BIS monitor placed over the standard frontal-temporal location and over the alternative nasal dorsum with simultaneous data collected for 24 hours. RESULTS: In the frontal-temporal location, the mean (SD) BIS score was 50.9 (15.0), average minimum BIS score was 47.0 (15.0), and average maximum BIS score was 58.4 (16.7). In the nasal dorsum location, the mean BIS score was 54.8 (21.6), average minimum BIS score was 52.8 (20.9), and average maximum BIS score was 58.0 (22.2). Baseline nonparametric tests showed nonsignificant P values for all variables except for Signal Quality Index. Generalized linear model analysis demonstrated significant differences between the 2 monitor locations (P < .0001). CONCLUSION: The results of this pilot study do not support using a BIS nasal montage as an alternative for patients in the neurocritical care unit.

Intraoperative Awareness and Recall: A Comparative Study of Dexmedetomidine and Propofol in Cardiac Surgery

BackgroundAwareness during general anesthesia is undesired and unanticipated patient wakefulness during surgery or recall of intraoperative events. Incidence of awareness in patients undergoing cardiac surgery is significantly higher than the overall incidence of 1% during general surgery. Awareness during cardiac surgery can be prevented by a number of methods. One such method is the supplemental, intraoperative use of sedative agents. Propofol, a bisubstituted phenol, is an intravenous general anesthetic that has been shown to reduce the incidence of awareness. Dexmedetomidine—an alpha2-adrenergic agonist with anxiolytic, opioid, and general anesthetic-sparing properties—is being considered for maintaining intraoperative depth of anesthesia. The purpose of this study was to evaluate the effect of dexmedetomidine on depth of anesthesia and to compare it with the effect of propofol in cardiac surgery.MethodsThis was a prospective, randomized, double-blind study conducted in a tertiary-care hospital. Sixty patients with American Society of Anesthesiologists (ASA) physical status I-III planned for elective open heart surgery were randomized into two groups of 30 patients each. Each patient of the dexmedetomidine group received an initial loading dose of dexmedetomidine at 1 mcg kg-1 over 10 minutes followed by infusion at the rate of 0.2–0.6 mcg kg-1 hr-1. Patients of the propofol group received propofol infusion at the rate of 0.25-1 mg kg-1 hr-1. An identical technique—of standard general anesthesia and routine physiological monitoring—was used in both groups. Bispectral scores were recorded at predetermined intervals during surgery and the target bispectral index (BIS) was kept at 50±10. The patients were assessed for awareness and recall 24 hours after tracheal extubation using the Brice Questionnaire.ResultsIntraoperative BIS scores remained within the target range in both groups; however, the BIS scores showed variable trends between the groups and were significantly lower in the dexmedetomidine group (p < 0.001). None of the patients in either group had recall of intraoperative events.ConclusionAdministration of dexmedetomidine was as effective in reducing awareness and recall in cardiac surgery compared to propofol. Thus, dexmedetomidine can be used as an alternative sedative agent to prevent awareness and recall in cardiac surgery.

Arousal from sedation in lower abdominal surgeries under spinal anesthesia: Comparison between dexmedetomidine and clonidine.

Background and Aim:Dexmedetomidine and clonidine are commonly used drugs for sedation during regional anesthesia. However, data regarding arousal time from sedation with these drugs is sparse. Hence, we designed a study to compare arousal time from sedation with dexmedetomidine and clonidine during spinal anesthesia. We also tried to find out the correlation between clinical and objective method used for assessing the depth of sedation.Materials and Methods:In this study, 120 patients were randomly assigned in two groups to receive either dexmedetomidine (Group DE, n = 60) or Clonidine (Group CL, n = 60). Group DE received 1 μg/kg of dexmedetomidine followed by infusion at 0.5 μg/kg/h while Group CL received 1 μg/kg of clonidine followed by infusion at 1 μg/kg/h and titration until targeted Ramsay sedation scale (RSS) score of 3–5 was achieved and maintained. RSS and bispectral (BIS) were monitored until arousal of the patients. The time to achieve RSS of 2 and BIS of 90 during recovery, the correlation between BIS and RSS score in both the study groups and duration of postoperative analgesia were noted.Statistical Analysis Used:Chi-square tests for nonparametric data and Student's t-test for parametric data were used. Correlation between RSS and BIS was calculated with spearman correlation method.Results:Arousal time from sedation and time to reach BIS score 90 was lower for Group DE as compared to Group CL (P = 0.001). Dexmedetomidine also increased the time to first postoperative analgesic request when compared with clonidine (198.23 ± 33.15 min vs. 150.65 ± 28.55 min, P = 0.01).Conclusions:Intravenous dexmedetomidine infusion has shorter arousal time from sedation than clonidine during spinal anesthesia. A strong correlation exists between BIS and RSS during recovery from sedation.

Bispectral index monitoring for diagnosis and assessment of severity of hepatic encephalopathy in cirrhotic patients

BackgroundRecent evidence suggests that bispectral index may aid in the diagnosis of hepatic encephalopathy. We evaluated its utility to diagnose, grade and monitor clinical course of hepatic encephalopathy in patients with cirrhosis. Methods200 patients (70.5% males, mean age 39.5±9.1 years) with cirrhosis and 20 healthy controls were enrolled prospectively. Cirrhotic patients were divided into groups based on encephalopathy grades I–IV assessed by West Haven criteria; minimal encephalopathy was assessed by psychometric tests. Bispectral index was measured at baseline and after one week of lactulose therapy in patients with overt encephalopathy, and after 3 months in patients with minimal encephalopathy. ResultsBispectral index scores were significantly different in patients with different grades of encephalopathy; 79.5±4.2, 67.5±4.3, 56.4±3.5, 44.8±3.9 and 85.0±4.3 respectively for grade I, II, III, IV overt and minimal hepatic encephalopathy, but similar (92.6±3.7 vs 93.75±2.8) in cirrhotics without encephalopathy and healthy controls. Bispectral scores’ cut off values for minimal and overt encephalopathy grade I, II, III, IV were 90.5 and 77.5, 70.5, 60.5, 50.5, respectively. Changes in bispectral index after treatment corresponded to cut-off scores for grades of overt and minimal hepatic encephalopathy. ConclusionsBispectral index was found to be useful in diagnosis, grading and monitoring of treatment response in cirrhotic patients with hepatic encephalopathy.

A Prospective, Randomized Comparative Study of Respiratory and Hemodynamic Monitoring during Colonoscopy using Remifentanyl Versus Propofol/Fentanyl

Objective: We hypothesized that remifentanil continuous infusion during colonoscopy in spontaneous respiration may give benefits in terms of quality of sedation and recovery compared to propofol, and that patients’ ventilatory drive and consciousness could be accurately evaluated by the continuous measurement of end-tidal CO2 (EtCO2), and of Bispectral Score (BIS) respectively. Methods: One-hundred and eighty patients scheduled for colonoscopy were randomized in two groups: 76 patients were included in Groupcontrol (propofol 0.5 mg/kg bolus plus infusion 1 mg/kg/h) and 78 patients in Gruopremi (0.5 mcg/Kg/1 min bolus plus infusion 0.08 mcg/kg/min, progressively reduced to 0.03 mcg/kg/min). Cardiovascular and respiratory variables were measured before induction and every 3 min throughout the procedure. Sedation level was estimated by BIS and Observer’s Assessment of Alertness/Sedation Scale (OAA/S). Respiratory function was evaluated by arterial oxygen saturation (SaO2) and EtCO2. Recovery from sedation and hospital discharge criteria were assessed by Modified Aldrete Score System (APRS) 30 min after colonoscopy completion. Results: Remifentanil was effective and well tolerated during colonoscopy. Hemodynamic parameters remained stable throughout the study steps in both groups. In Groupremi OAA/S and BIS score were higher (p<0.001), and EtCO2 (p<0.5) lower that in Groupcontrol. Recovery time was faster in the Groupremi (p<0.01). Conclusions: Our data show that analgosedation with remifentanil allowed to obtain a good quality colonoscopy without respiratory and hemodynamic impairment and with faster recovery than moderate sedation propofol/fentanyl. Moreover, BIS and EtCO2 monitoring proved to be well suited to evaluate the trend variations of patients’ sedation level and respiratory drive.

The Effect of Doxapram Hydrochloride on Bispectral (BIS) Index and Recovery from Desflurane Inhalational Anesthesia

Background: Doxapram hydrochloride is a respiratory stimulant that produces arousal effects in patients under anesthesia. We investigated the effects of doxapram on the recovery time and BIS index of patients administered desflurane inhalational anesthesia. Methods: 40 patients who underwent general anesthesia using desflurane that had an ASA physical status of I or II received either 1 mg/kg of doxapram hydrochloride (doxapram group, n = 20) or normal saline (control group, n = 20) IV at end of surgery. Anesthetic recovery after the injection of doxapram was then determined based on the time to eye opening in response to verbal command, hand squeezing on command, time to extubation, and Aldrete recovery score. BIS index, systolic blood pressure, tidal volume and heart rate were recorded every minute for up to thirteen minutes. Results: The doxapram group showed significantly shorter times to emergence based on eye opening in response verbal command (sec) (409 ± 114 vs 320 ± 116), hand squeezing on command (sec) (458 ± 119 vs 351 ± 114) and extubation (sec) (491 ± 103 vs 418 ± 79) compared to control group. The BIS score was not significantly different between the two groups. Conclusions: The Bis index was not significant higher in the doxapram group, with the exception of the measurement recorded at 2 minutes, however the recovery time from desflurane inhalational anesthesia was faster in the doxapram group than the control group. (Korean J Anesthesiol 2008; 54: 12∼7)

Conscious sedation of children with propofol is anything but conscious.

To determine the depth of sedation required for bone marrow aspiration and intrathecal injection of chemotherapeutic agents in children using a bispectral (BIS) index monitor and clinical assessment by an independent observer. Sixteen children who were undergoing 19 intrathecal chemotherapy and bone marrow aspirations were enrolled in the study. Their ages ranged from 23 months to 190 months with a mean of 79 months. The BIS index was recorded every 5 minutes by an independent observer. The patients received only intravenous propofol for sedation. There were no complications during the procedures. The mean BIS score was 62.8+/- 9.6. The mean low BIS score was 29.7 +/- 13.7, indicating a level of deep sedation and/or general anesthesia was necessary to induce the desired stated of consciousness that would permit the practitioner to perform the procedure. The average dose of propofol was 166 +/- 47 microg/kg/min. Mean Aldrete score for level of consciousness was 0.9 +/- 0.4, indicating a depressed level of consciousness. The mean activity level was 1.0+/- 0.4, indicating impaired movement. Children who undergo conscious sedation with propofol for intrathecal chemotherapy and bone marrow aspiration demonstrate BIS values and clinical assessments consistent with deep sedation. Because of an increased risk of adverse events when children undergo deep sedation, appropriate parental informed consent, age-appropriate resuscitative equipment, and skilled anesthesia personnel should be present for rescue in the event of cardiovascular and respiratory complications from deep sedation.