This randomized controlled trial compared Bispectral Index (BIS) values in 40 patients after a modified rapid sequence induction using thiopentone 4 mg/kg or propofol 2 mg/kg with rocuronium 0.6 mg/kg as muscle relaxant. Endotracheal intubation was performed at 60 seconds from induction of anaesthesia and BIS values were recorded for three minutes after induction. At the 120, 150 and 180 second measurements there was a significantly greater proportion of subjects with BIS values < or = 60 ("anaesthetized") in the propofol group compared with the thiopentone group (P values < 0.02, < 0.01 and < 0.01 respectively). All intubations were completed within two minutes. No explicit recall of intubation was detected clinically with either induction agent. The BIS scores we have measured suggest that thiopentone 4 mg/kg is more likely to be associated with lighter planes of anaesthesia and consequent risk of awareness than propofol 2 mg/kg, if intubation is delayed or prolonged.
Anaesthesia is a multivariable problem where a combination of drugs are used to induce desired hypnotic, analgesia and immobility states. The automation of anaesthesia may improve the safety and cost-effectiveness of anaesthesia. However, the realization of a safe and reliable multivariable closed-loop control of anaesthesia is yet to be achieved due to a manifold of challenges. In this paper, several significant challenges in automation of anaesthesia are discussed, namely model uncertainty, controlled variables, closed-loop application and dependability. The increasingly reliable measurement device, robust and adaptive controller, and better fault tolerance strategy are paving the way for automation of anaesthesia.
Mitragynine is the main alkaloid isolated from the leaves of Mitragyna speciosa Korth (Kratom). Kratom has been widely used to relieve pain and opioid withdrawal symptoms in humans but may also cause memory deficits. Here we investigated the changes in brain electroencephalogram (EEG) activity after acute and chronic exposure to mitragynine in freely moving rats. Vehicle, morphine (5 mg/kg) or mitragynine (1, 5 and 10 mg/kg) were administered for 28 days, and EEG activity was repeatedly recorded from the frontal cortex, neocortex and hippocampus. Repeated exposure to mitragynine increased delta, but decreased alpha powers in both cortical regions. It further decreased delta power in the hippocampus. These findings suggest that acute and chronic mitragynine can have profound effects on EEG activity, which may underlie effects on behavioral activity and cognition, particularly learning and memory function.
An ideal anaesthetic for electroconvulsive therapy (ECT) should have rapid onset and offset with no effect on seizure duration, and provide cardiovascular stability during the procedure. Propofol is commonly used, even though it has been shown to shorten seizure duration which might affect the efficacy of ECT Etomidate has been advocated as an alternative. This prospective, randomised, single-blind, crossover study was conducted to compare the effects of etomidate (Etomidate-Lipuro, B. Braun Ltd, Melsungen, Germany) and propofol (Diprivan, AstraZeneca, UK) on seizure duration as well as haemodynamic parameters in patients undergoing ECT Twenty patients aged between 18 and 70 years were recruited. Group I received etomidate 0.3 mg/kg for the first course of ECT (Group IA) and propofol 1.5 mg/kg for the second ECT (Group IB), while Group II received propofol for the first ECT (Group IIA) and etomidate for the second ECT (Group IIB). There was a washout period of two to three days in between procedures. Parameters recorded included motor seizure duration, electroencephalogram seizure duration, blood pressure and heart rate. Analysis demonstrated neither period effect nor treatment period interaction. Etomidate was associated with a significantly longer motor and electroencephalogram seizure duration compared with propofol (P < 0.01). Neither drug demonstrated consistent effects in suppressing the rise in heart rate or blood pressure during ECT Myoclonus and pain on injection were the most common adverse effects in etomidate group and propofol group respectively. Etomidate is a useful anaesthetic agent for ECT and should be considered in patients with inadequate seizure duration with propofol.
Methadone as the most prevalent opioid substitution medication has been shown to influence the neurophysiological functions among heroin addicts. However, there is no firm conclusion on acute neuroelectrophysiological changes among methadone-treated subjects as well as the effectiveness of methadone in restoring brain electrical abnormalities among heroin addicts. This study aims to investigate the acute and short-term effects of methadone administration on the brain's electrophysiological properties before and after daily methadone intake over 10 weeks of treatment among heroin addicts. EEG spectral analysis and single-trial event-related potential (ERP) measurements were used to investigate possible alterations in the brain's electrical activities, as well as the cognitive attributes associated with MMN and P3. The results confirmed abnormal brain activities predominantly in the beta band and diminished information processing ability including lower amplitude and prolonged latency of cognitive responses among heroin addicts compared to healthy controls. In addition, the alteration of EEG activities in the frontal and central regions was found to be associated with the withdrawal symptoms of drug users. Certain brain regions were found to be influenced significantly by methadone intake; acute effects of methadone induction appeared to be associative to its dosage. The findings suggest that methadone administration affects cognitive performance and activates the cortical neuronal networks, resulting in cognitive responses enhancement which may be influential in reorganizing cognitive dysfunctions among heroin addicts. This study also supports the notion that the brain's oscillation powers and ERPs can be utilized as neurophysiological indices for assessing the addiction treatment traits.