Evaluation of bispectral index (BIS) as an indicator of central nervous system depression in horses anesthetized with propofol.
The bispectral index (BIS) was evaluated as an indicator of central nervous system (CNS) depression in horses anesthetized with propofol. Five non-premedicated horses were anesthetized with 7 mg/kg, IV propofol and the minimum infusion rate (MIR) of propofol required to maintain anesthesia was determined during intermittent positive pressure ventilation in each horse. The BIS was determined 20 min later and after stabilization at 2.0 MIR, 1.5 MIR, and 1.0 MIR. The BIS was also recorded after the cessation of propofol infusion when the horses regained spontaneous breathing and swallowing reflex. The MIR and plasma concentration (Cp) of propofol were 0.20 +/- 0.03 mg/kg/min and 17.5 +/- 4.0 microg/ml, respectively. The BIS value and Cp were 59 +/- 13 and 26.7 +/- 8.6 microg/ml at 2.0 MIR, 63 +/- 9 and 22.9 +/- 9.7 microg/ml at 1.5 MIR, 64 +/- 13 and 20.1 +/- 5.9 microg/ml at 1.0 MIR, 64 +/- 24 and 13.0 +/- 2.8 microg/ml at return of spontaneous breathing, and 91 +/- 4 and 11.0 +/- 3.4 microg/ml when the swallowing reflex returned, respectively. The BIS value was significantly less in anesthetized horses compared to horses once swallowing returned (p=0.025). The BIS value was significantly correlated with the propofol Cp (r=-0.625, p=0.001). There was not a significant difference in the BIS values during the MIR multiples of propofol. The BIS was a useful indicator of awakening but did not indicate the degree of CNS depression during propofol-anesthesia in horses. (+info)
Correlation between bispectoral index and predicted effect-site concentration of propofol in different levels of target-controlled, propofol induced sedation in healthy volunteers.
INRODUCTION: Bispectral Index is an objective tool to assess electroencephalographic activity and measure the effect of certain sedatives and hypnotics on the brain. In addition, there are certain subjective tools such as the observer's assessment of alertness and sedation which are used. The correlation between BIS and the concentration of propofol in the brain, and the relationship between these subjective and objective tools in assessing sedation levels are the subject of this study. METHODS: Thirty healthy volunteers enrolled in this prospective observational study. They were sedated with a target controlled infusion of propofol with an initial target of 0.8 microg.mL(-1)and an increase in target to 0.2 microg.mL(-1) ten minutes after equilibration of the predicted and set target concentrations. In each sedation score, the Bispectral Index value and predicted effect site concentration of propofol were recorded and analyzed. Analysis of variance and significant differences between groups were analyzed by paired t-test. Correlations between Bispectral Index and effect site concentration of propofol at each sedation score and the relationship of BIS and effect site concentration of propofol to each sedation score were assessed and analyzed by nonparametric Spearman's rho. RESULTS: The means of Bispectral Index and effect site concentration of propofol at each sedation score showed a significant difference with the following score. Additionally, Bispectral Index and effect site concentration of propofol showed a significant negative correlation in sedation scores 3 and 2 when inducing sedation. In other sedation scores or when reversing the sedation, no strong correlation was noted. CONCLUSION: Both Bispectral Index and effect site concentration of propofol indicate a good estimate of sedation levels; however their correlations are significant and negative only at moderate and deep sedation levels, and during the induction of sedation. (+info)
Music composition from the brain signal: representing the mental state by music.
Bispectral index (BIS) monitoring of acute encephalitis with refractory, repetitive partial seizures (AERRPS).
Diagnosis of ictal discharges during epileptic activity should be based on raw electroencephalography (EEG). The apparatus necessary for such a diagnosis would typically require time to properly set up and operate. The bispectral index (BIS), an EEG-derived parameter that is easy to establish and easy to use, has been shown to correlate with numerous EEG conditions and may represent a useful tool. Acute encephalitis with refractory, repetitive, partial seizures (AERRPS) is an epileptic syndrome first described by Sakuma in Japan in 2001. We assessed the utility of using BIS monitoring as a diagnostic tool and as a monitor of anticonvulsive therapy in a 14-year-old patient admitted to the intensive care unit with AERRPS. After BIS monitor montage, BIS, electromyography (EMG) and raw EEG data were continuously recorded. Epileptic seizures lasting 1-2 min were repeated every 3-4 min. Using paired t-test analysis, mean +/- SD BIS and EMG peak values at the start of epileptic seizures (94.5+/-3.6, 55.8+/-2.5 dB) were significantly higher than values measured at the end of seizures (55.1+/-12.5, 34.5+/-2.8 dB), respectively. Real-time EEG revealed bursts of epileptiform discharges replaced by slow d and q waves with ictal remissions. During induced pharmacologic barbiturate/diazepam coma, BIS decreased to near isoelectricity (11.9+/-2.5) with a steady increase in suppression ratio (65.5+/-9.7). The characteristic BIS profile of repetitive 1-2 min high EEG/EMG activity could serve as an indicator of a global increase in cerebral activity with seizures. Our report suggests that BIS, an easy-to-use device, might be helpful in monitoring clinical trends after EEG confirmation of diagnosis as well as in successfully depicting the efficacy of therapy. (+info)
Association of perioperative risk factors and cumulative duration of low bispectral index with intermediate-term mortality after cardiac surgery in the B-Unaware Trial.