Emergence Electroencephalography in an Unresponsiveness Geriatric Patient in the Postanesthesia Care Unit: A Case Report.

Incomplete neurological awakening manifested as aberrant patterns of electroencephalography (EEG) at emergence may be responsible for an unresponsive patient in the postanesthesia care unit (PACU). We describe a case of an individual who remained unresponsive but awake in the PACU. Retrospective, intraoperative EEG analysis showed low alpha power and a sudden shift from deep delta to arousal preextubation.

Seeing is Believing: Chasing Sevoflurane Vapor Trails.

Purpose: Sevoflurane is an inhalational general anesthetic that has been used recently to treat chronic, painful lesions, reportedly supporting analgesia and wound healing. The potential for repeated exposure to off-gassed sevoflurane vapor, especially outside the air-conditioned operating theatre environment, is of some concern.

Design: This paper explores the qualitative and quantitative pathing of off-gassed sevoflurane from a topically applied liquid source.

Preliminary pharmacokinetics and patient experience of jet-injected dexmedetomidine in healthy adults.

Jet injection is a drug delivery system without a needle. A compressed liquid drug formulation pierces the skin, depositing the drug into the subcutaneous or intramuscular tissues. We investigated the pharmacokinetics and patient experience of dexmedetomidine administered using jet injection in six healthy adult study participants.

Tissue oxygen partial pressure as a viability metric for ex vivo brain tissue slices.

Background: Despite the prevalent use of the ex vivo brain slice preparation in neurophysiology research, a reliable method for judging tissue viability - and thus suitability of a slice for inclusion in an experiment - is lacking. The utility of indirect electrophysiological measures of tissue health is model-specific and needs to be used cautiously. In this study, we verify a more direct test of slice viability, based on tissue oxygen consumption rate.

Determination of Krogh Coefficient for Oxygen Consumption Measurement from Thin Slices of Rodent Cortical Tissue Using a Fick's Law Model of Diffusion.

To investigate the impact of experimental interventions on living biological tissue, ex vivo rodent brain slices are often used as a more controllable alternative to a live animal model. However, for meaningful results, the biological sample must be known to be healthy and viable. One of the gold-standard approaches to identifying tissue viability status is to measure the rate of tissue oxygen consumption under specific controlled conditions.

Encapsulation Dynamics of Neuromuscular Blocking Drugs by Sugammadex.

Background: The clinical actions of sugammadex have been well studied, but the detailed molecular mechanism of the drug encapsulation process has not been systematically documented. The hypothesis was that sugammadex would attract rocuronium and vecuronium via interaction with the sugammadex side-chain "tentacles," as previously suggested.

Methods: Computational molecular dynamics simulations were done to investigate docking of sugammadex with rocuronium and vecuronium.

Deconstructing delirium in the post anaesthesia care unit.

The course of neuro-cognitive recovery following anaesthesia and surgery is distinctive and poorly understood. Our objective was to identify patterns of neuro-cognitive recovery of the domains routinely assessed for delirium diagnosis in the post anaesthesia care unit (PACU) and to compare them to the cognitive recovery patterns observed in other studies; thereby aiding in the identification of pathological (high risk) patterns of recovery in the PACU. We also compared which of the currently available tests (3D-CAM, CAM-ICU, and NuDESC) is the best to use in PACU.

The general anaesthetic propofol prevents cerebrocortical potentiation in neocortical mouse brain slices.

Propofol is well known to cause amnesia independent of its sedative effect. Memory consolidation processes in the hippocampus have been proposed as a target - however the neural substrates for propofol's amnesic actions remain understudied and poorly described. In particular, the potential role of the cerebral cortex has not been investigated.

Non-NMDA Mechanisms of Analgesia in Ketamine Analogs.

Despite 50 years of clinical use and experimental endeavor the anesthetic, analgesic, and psychomimetic effects of ketamine remain to be fully elucidated. While NMDA receptor antagonism has been long held as ketamine's fundamental molecular action, interrogation of bespoke ketamine analogs with known absent NMDA binding, yet profound anesthetic and analgesia fingerprints, suggests alternative targets are responsible for these effects. Herein we describe experimental findings utilizing such analogs as probes to explore ketamine-based analgesic molecular targets.

A systematic exploration of local network state space in neocortical mouse brain slices.

The ex vivo cortical slice is an extremely versatile preparation, but its utility ultimately depends on understanding its limitations and functional constraints. A question for experimentalists new to the field of cortical slice electrophysiology might be - what are the different network dynamical states available to a cortical slice as a function of excitatory drive? The purpose of this study is to provide a coherent answer to this question, within the context of extracellularly recorded population field potentials. Cortical slices (400 µm) were prepared from adult male or female C57 mice.

Microalgae-based photosynthetic strategy for oxygenating avascularised mouse brain tissue - An in vitro proof of concept study.

Hypoxic brain injury is a leading cause of loss of quality of life globally for which there are currently no effective treatments. There has been increasing interest in incorporating photosynthesising agents into hypoxic tissue as a mechanism for in situ oxygen delivery, independent of vascular perfusion. To date this has not been tested in the brain.

The molecular dynamics of possible inhibitors for SARS-CoV-2.

The novel coronavirus SARS-CoV-2, responsible for the present COVID-19 global pandemic, is known to bind to the angiotensin converting enzyme-2 (ACE2) receptor in human cells. A possible treatment of COVID-19 could involve blocking ACE2 and/or disabling the spike protein on the virus. Here, molecular dynamics simulations were performed to test the binding affinities of nine candidate compounds.

Electrophysiological field potential identification of an intact GABAergic system in mouse cortical slices.

In brain slice experiments there's currently no validated electrophysiological method for differentiating viability between GABAergic and glutamatergic cell populations. Here we investigated the neurophysiology of high frequency field potential activity - and its utility for probing the functional state of the GABAergic system in brain slices. Field potentials were recorded from mouse cortical slices exposed to 50 mM potassium ("elevated-K") and the induced high frequency (>20 Hz) response characterized pharmacologically.

Cerebrospinal fluid oxygen optimisation for rescue of metabolically challenged in vitro cortical brain tissue.

Hypoxic-ischaemic brain injury is a major cause of morbidity and mortality internationally. Using an in vitro isolated cortex model, this study investigated the optimal cerebrospinal fluid oxygenation parameters for rescuing metabolically challenged cortical tissue. In particular, we asked whether maximizing oxygen content with oxygen nanobubbles could support improved tissue recovery.

Application of a benchtop colorimetric method for quantification of blood propofol levels.

Quantification of plasma propofol (2,6-diisopropylphenol) in the context of clinical anaesthesia is challenging because of the need for offline blood sample processing using specialised laboratory equipment and techniques. In this study we sought to refine a simple procedure using solid phase extraction and colorimetric analysis into a benchtop protocol for accurate blood propofol measurement. The colorimetric method based on the reaction of phenols (e.

Impact of variation in tissue preparation methodology on the functional outcome of neocortical mouse brain slices.

The in vitro cortical slice preparation is a widely used tool for electrophysiological investigation of brain neurophysiology. However, slice quality can be highly variable despite attempts to standardise practice. The purpose of this study was to determine the extent to which this variability is due to sensitivity to aspects of the preparation methodology.

Relationship between artificial cerebrospinal fluid oxygenation, slice depth and tissue performance in submerged brain slice experiments.

One of the challenges for slice experimentalists is achieving optimal tissue oxygenation. One area that has not been addressed in submerged slices is the relationship between oxygenation of the artificial cerebrospinal fluid, slice depth and tissue performance. In this study we varied the depth of slice submersion, measured the oxygen profile in the solution and related these to slice activity in the form of spontaneous population events.

A Metabolic Mechanism for Anaesthetic Suppression of Cortical Synaptic Function in Mouse Brain Slices-A Pilot Investigation.

Regulation of synaptically located ionotropic receptors is thought to be the main mechanism by which anaesthetics cause unconsciousness. An alternative explanation, which has received much less attention, is that of primary anaesthetic disruption of brain metabolism via suppression of mitochondrial proteins. In this pilot study in mouse cortical slices, we investigated the effect of disrupting cellular metabolism on tissue oxygen handling and cortical population seizure-like event (SLE) activity, using the mitochondrial complex I inhibitor rotenone, and compared this to the effects of the general anaesthetics sevoflurane, propofol and ketamine.

Structure-Activity Relationships for the Anaesthetic and Analgaesic Properties of Aromatic Ring-Substituted Ketamine Esters.

A series of benzene ring substituted ketamine -alkyl esters were prepared from the corresponding substituted norketamines. Few of the latter have been reported since they have not been generally accessible via known routes. We report a new general route to many of these norketamines via the Neber (oxime to α-aminoketone) rearrangement of readily available substituted 2-phenycyclohexanones.