Propofol anesthesia alters cortical traveling waves

Oscillatory dynamics in cortex seem to organize into traveling waves that serve a variety of functions. Recent studies show that propofol, a widely used anesthetic, dramatically alters cortical oscillations by increasing slow-delta oscillatory power and coherence. It is not known how this affects traveling waves. We compared traveling waves across the cortex of non-human primates (NHPs) before, during, and after propofol-induced loss-of-consciousness (LOC). After LOC, traveling waves in the slow-delta (~ 1Hz) range increased, grew more organized, and travelled in different directions relative to the awake state. Higher frequency (8-30 Hz) traveling waves, by contrast, decreased, lost structure, and switched to directions where the slow-delta waves were less frequent. The results suggest that LOC may be due, in part, to changes in slow-delta traveling waves that, in turn, alter and disrupt traveling waves in the higher frequencies associated with cognition.

The influence of neuromuscular blockade on phase lag entropy and bispectral index: A randomized, controlled trial

The aim of this study is to compare the effects of neuromuscular blockade (NMB) on phase lag entropy (PLE) and the bispectral index (BIS). We recorded the BIS, electromyograph (EMG) activity on a BIS monitor (EMG_BIS), PLE, and EMG activity on a PLE monitor (EMG_PLE) in 40 patients receiving general anesthesia. During the awake state, we analyzed the changes in parameters before and 2 min after the eyes were closed. During sedation, we compared the changes in the parameters before and at 4 min after injecting rocuronium (group R) or normal saline (group C) between the two groups. During anesthesia, we compared the changes in parameters before and at 4 min after injecting sugammadex (group B) or normal saline (group D) between the two groups. During the awake state, the BIS, EMG_BIS, and EMG_PLE, but not PLE, decreased significantly with closed eyes. An effect of EMG on the BIS was evident, but not on PLE. During sedation, the BIS decreased with the decrease in EMG_BIS regardless of NMB caused by rocuronium, but NMB decreased PLE, although the degree of the decrease in EMG_PLE after NMB was similar to that after placebo. To determine the effect of NMB on electroencephalograms (EEGs) in groups R and C, we plotted the power spectra before and at 4 min after injecting rocuronium or normal saline. Changes in slow and delta frequency bands were observed at 4 min after injecting rocuronium relative to before injecting rocuronium. There was no effect of EMG on either the BIS or PLE during anesthesia. In conclusion, the effect of electromyograph activity and/or neuromuscular blockade on BIS or PLE depends on the level of consciousness.

GABAergic Neurons in the Dorsal–Intermediate Lateral Septum Regulate Sleep–Wakefulness and Anesthesia in Mice

Background The γ-aminobutyric acid–mediated (GABAergic) inhibitory system in the brain is critical for regulation of sleep–wake and general anesthesia. The lateral septum contains mainly GABAergic neurons, being cytoarchitectonically divided into the dorsal, intermediate, and ventral parts. This study hypothesized that GABAergic neurons of the lateral septum participate in the control of wakefulness and promote recovery from anesthesia. Methods By employing fiber photometry, chemogenetic and optogenetic neuronal manipulations, anterograde tracing, in vivo electrophysiology, and electroencephalogram/electromyography recordings in adult male mice, the authors measured the role of lateral septum GABAergic neurons to the control of sleep–wake transition and anesthesia emergence and the corresponding neuron circuits in arousal and emergence control. Results The GABAergic neurons of the lateral septum exhibited high activities during the awake state by in vivo fiber photometry recordings (awake vs. non–rapid eye movement sleep: 3.3 ± 1.4% vs. –1.3 ± 1.2%, P < 0.001, n = 7 mice/group; awake vs. anesthesia: 2.6 ± 1.2% vs. –1.3 ± 0.8%, P < 0.001, n = 7 mice/group). Using chemogenetic stimulation of lateral septum GABAergic neurons resulted in a 100.5% increase in wakefulness and a 51.2% reduction in non–rapid eye movement sleep. Optogenetic activation of these GABAergic neurons promoted wakefulness from sleep (median [25th, 75th percentiles]: 153.0 [115.9, 179.7] s to 4.0 [3.4, 4.6] s, P = 0.009, n = 5 mice/group) and accelerated emergence from isoflurane anesthesia (514.4 ± 122.2 s vs. 226.5 ± 53.3 s, P < 0.001, n = 8 mice/group). Furthermore, the authors demonstrated that the lateral septum GABAergic neurons send 70.7% (228 of 323 cells) of monosynaptic projections to the ventral tegmental area GABAergic neurons, preferentially inhibiting their activities and thus regulating wakefulness and isoflurane anesthesia depth. Conclusions The results uncover a fundamental role of the lateral septum GABAergic neurons and their circuit in maintaining awake state and promoting general anesthesia emergence time. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Brain Energy Metabolism in Two States of Mind Measured by Phosphorous Magnetic Resonance Spectroscopy

Introduction: Various functional neuroimaging studies help to better understand the changes in brain activity during meditation. The purpose of this study was to investigate how brain energy metabolism changes during focused attention meditation (FAM) state, measured by phosphorous magnetic resonance spectroscopy (31P-MRS).Methods:31P-MRS imaging was carried out in 27 participants after 7 weeks of FAM training. Metabolite ratios and the absolute values of metabolites were assessed after meditation training in two MRI measurements, by comparing effects in a FAM state with those in a distinct focused attention awake state during a backwards counting task.Results: The results showed decreased phosphocreatine/ATP (PCr/ATP), PCr/ inorganic phosphate (Pi), and intracellular pH values in the entire brain, but especially in basal ganglia, frontal lobes, and occipital lobes, and increased Pi/ATP ratio, cerebral Mg, and Pi absolute values were found in the same areas during FAM compared to the control focused attention awake state.Conclusions: Changes in the temporal areas and basal ganglia may be interpreted as a higher energetic state induced by meditation, whereas the frontal and occipital areas showed changes that may be related to a down-regulation in ATP turnover, energy state, and oxidative capacity.

Awake Craniotomy

Prior to the advent of anesthesia, performing surgical procedures on patients in the awake state was the order of the day. In modern times, especially with the continued advancement and safety of anesthesia, such a practice of performing surgery on a patient in the awake state might appear unnecessary, and perhaps even medieval. However, this practice still does intentionally occur for a subset of neurosurgery patients. This unique dimension of the procedure places special demands on the anesthesiologist’s knowledge base, skill and training in order to produce a successful patient outcome. This chapter delves into salient aspects of patient selection, operating room setup, monitoring and communication considerations, pharmacologic regimens, regional anesthetic options and a thorough list of complications for which to be prepared. This review contains 5 figures, 5 tables, and 69 references. Keywords: awake craniotomy, functional neurosurgery, eloquent cortex, awake-asleep-awake, electrocorticography, epilepsy, deep brain stimulator, dexmedetomidine, intraoperative seizure

Application of extracorporeal membrane oxygenation to treatment of serious tracheal stenosis caused by relapsing polychondritis: a case report and literature review

Relapsing polychondritis (RP) is a multisystemic rheumatic disease characterized by widespread and potentially destructive inflammatory lesions of the cartilage. The rarity of this disease and the lack of pathological diagnostic laboratory tests can occasionally lead to delayed diagnosis. We herein describe a 51-year-old woman with RP. She was sent to our hospital 4 days after the development of an upper respiratory tract infection with difficulty breathing. Her clinical condition significantly improved after the performance of extracorporeal membrane oxygenation support in an awake state, implantation of a tracheal stent, and administration of steroid therapy. Airway involvement of RP may be life-threatening. In this case, endotracheal intubation would have undoubtedly been very dangerous. Extracorporeal membrane oxygenation can be performed in an awake state to maintain oxygenation and improve the chance of survival.

Simulating Dynamics of Circulation in the Awake State and Different Stages of Sleep Using Non-autonomous Mathematical Model With Time Delay

We propose a mathematical model of the human cardiovascular system. The model allows one to simulate the main heart rate, its variability under the influence of the autonomic nervous system, breathing process, and oscillations of blood pressure. For the first time, the model takes into account the activity of the cerebral cortex structures that modulate the autonomic control loops of blood circulation in the awake state and in various stages of sleep. The adequacy of the model is demonstrated by comparing its time series with experimental records of healthy subjects in the SIESTA database. The proposed model can become a useful tool for studying the characteristics of the cardiovascular system dynamics during sleep.

The impact of topical lidocaine and timing of LMA removal on the incidence of airway events during the recovery period in children: a randomized controlled trial

Background The timing of laryngeal mask airway (LMA) removal remains undefined. This study aimed to assess the optimal timing for LMA removal and whether topical anesthesia with lidocaine could reduce airway adverse events. Methods This randomized controlled trial assessed one-to-six-year-old children with ASA I-II scheduled for squint correction surgery under general anesthesia. The children were randomized into the LA (lidocaine cream smeared to the cuff of the LMA before insertion, with mask removal in the awake state), LD (lidocaine application and LMA removal under deep anesthesia), NLA (hydrosoluble lubricant application and LMA removal in the awake state) and NLD (hydrosoluble lubricant application and LMA removal in deep anesthesia) groups. The primary endpoint was a composite of irritating cough, laryngeal spasm, SpO2 < 96%, and glossocoma in the recovery period in the PACU. The secondary endpoints included the incidence of pharyngalgia and hoarseness within 24 h after the operation, duration of PACU stay, and incidence of agitation in the recovery period. The assessor was unblinded. Results Each group included 98 children. The overall incidence of adverse airway events was significantly lower in the LA group (9.4%) compared with the LD (23.7%), NLA (32.6%), and NLD (28.7%) groups (P=0.001). Cough and laryngeal spasm rates were significantly higher in the NLA group (20.0 and 9.5%, respectively) than the LA (5.2 and 0%, respectively), LD (4.1 and 1.0%, respectively), and NLD (9.6 and 2.1%, respectively) groups (P=0.001). Glossocoma incidence was significantly lower in the LA and NLA groups (0%) than in the LD (19.6%) and NLD (20.2%) groups (P< 0.001). At 24 h post-operation, pharyngalgia incidence was significantly higher in the NLA group (15.8%) than the LA (3.1%), LD (1.0%), and NLD (3.2%) groups (P< 0.001). Conclusions LMA removal in the awake state after topical lidocaine anesthesia reduces the incidence of postoperative airway events. Trial registration ChiCTR, ChiCTR-IPR-17012347. Registered August 12, 2017.