The influence of anesthesia- body mass index and chronicity of the injury on the reliability of diagnostic tests for anterior cruciate ligament rupture

This study aimed to analyze the accuracy and interobserver reliability of the four common diagnostic tests for anterior cruciate ligament (ACL) rupture. The effect of anesthesia, chronicity of the injury and patient’s body mass index (BMI) on the reliabilities was also assessed. Patients who underwent arthroscopic knee surgery were examined before the surgery and under anesthesia by three observers categorized based on their experience levels. One hundred two patients were evaluated to determine the accuracy of these tests. Sixty-two patients with ACL rupture were further examined to assess the effect of BMI (≤ 25 kg/m2, or > 25 kg/m2) and chronicity (≤ 4 or > 4 weeks) of the injury on reliabilities with using the Fleiss kappa method. The Lachman test performed under anesthesia had the highest sensitivity (100%, 100%, and 96.7%). In contrast, pivot shift and lever sign tests had the lowest sensitivity both in awake (24.2%, 17.7%, 8.1% and 37.1%, 33.8%, 29%) and anesthetized condition (75.8%, 75.8%, 67.7% and 41.9%, 43.5%, 40.3%). Specificities of the tests except pivot shift were negatively affected when performed under anesthesia. The reliability of the anterior drawer test was perfect under anesthesia. The lever sign test had the highest reliability in the awake condition in patients with a BMI of > 25 kg/m2. Furthermore, the reliabilities of the anterior drawer, Lachman, and pivot-shift tests in awake condition were found to be increased in patients with a chronic injury. Finally, the examiner’s experience is not important for the physical diagnosis of ACL rupture.

Impact of propofol sedation on the diagnostic accuracy of hepatic venous pressure gradient measurements in patients with cirrhosis

Background Measurement of the hepatic venous pressure gradient (HVPG) is the gold standard to evaluate the presence and severity of portal hypertension. The procedure is generally safe and well tolerated, but nevertheless, some patients demand for sedation. However, it is unknown whether propofol sedation would impair the accuracy of portal pressure measurements. Methods This is a prospective observational cohort study including cirrhotic patients with suspected portal hypertension undergoing invasive measurement of HVPG. Measurements of HVPG were performed in awake condition as well as under sedation with propofol infusion. Results In total, 37 patients were included. Mean HVPG in awake condition was 15.9 mmHg (IQR 13–19) and during sedation 14.1 mmHg (IQR 12–17). While measures of free hepatic vein pressure (FHVP) were not altered after propofol sedation (p = 0.34), wedged hepatic vein pressure values (WHVP) decreased in an average by 2.05 mmHg (95% CI − 2.46 to − 1.16; p < 0.001) which was proportional to the magnitude of HVPG. In 31 out of 37 patients (83.8%), portal hypertension with HVPG ≥ 12 mmHg was found. Under sedation with propofol, two patients (5.4%) with borderline values would have been incorrectly classified as < 12 mmHg. After adjustment for the average difference of − 10%, all patients were correctly classified. Intraclass correlation coefficient between HVPG measurement in awake condition and under propofol sedation was 0.927 (95% CI 0.594–0.975). Conclusions Propofol sedation during HVPG measurements is generally safe, however it may lead to relevant alterations of HVPG readings.

MRS-measured glutamate versus GABA reflects excitatory versus inhibitory neural activities in awake mice

To assess if magnetic resonance spectroscopy (MRS)-measured Glutamate (Glu) and GABA reflect excitatory and inhibitory neural activities, respectively, we conducted MRS measurements along with two-photon mesoscopic imaging of calcium signals in excitatory and inhibitory neurons of living, unanesthetized mice. For monitoring stimulus-driven activations of a brain region, MRS signals and mesoscopic neural activities were measured during two consecutive sessions of 15-min prolonged sensory stimulations. In the first session, putative excitatory neuronal activities were increased, while inhibitory neuronal activities remained at the baseline level. In the second half, while excitatory neuronal activities remained elevated, inhibitory neuronal activities were significantly enhanced. We assessed regional neurochemical statuses by measuring MRS signals, which were overall in accordance with the neural activities, and neuronal activities and neurochemical statuses in a mouse model of Dravet syndrome under resting condition. Mesoscopic assessments showed that activities of inhibitory neurons in the cortex were diminished relative to wild-type mice in contrast to spared activities of excitatory neurons. Consistent with these observations, the Dravet model exhibited lower concentrations of GABA than wild-type controls. Collectively, the current investigations demonstrate that MRS-measured Glu and GABA can reflect spontaneous and stimulated activities of neurons producing and releasing these neurotransmitters in an awake condition.

Topological analysis of differential effects of ketamine and propofol anaesthesia on brain dynamics

Research has found that the vividness of conscious experience is related to brain dynamics. Despite both being anaesthetics, propofol and ketamine produce different subjective states: we explore the different effects of these two anaesthetics on the structure of dynamic attractors reconstructed from electrophysiological activity recorded from cerebral cortex of two macaques. We used two methods: the first embeds the recordings in a continuous high-dimensional manifold on which we use topological data analysis to infer the presence of higher-order dynamics. The second reconstruction, an ordinal partition network embedding, allows us to create a discrete state-transition network, which is amenable to information-theoretic analysis and contains rich information about state-transition dynamics. We find that the awake condition generally had the ‘richest’ structure, visiting the most states, the presence of pronounced higher-order structures, and the least deterministic dynamics. By contrast, the propofol condition had the most dissimilar dynamics, transitioning to a more impoverished, constrained, low-structure regime. The ketamine condition, interestingly, seemed to combine aspects of both: while it was generally less complex than the awake condition, it remained well above propofol in almost all measures. These results provide deeper and more comprehensive insights than what is typically gained by using point-measures of complexity.

Stent-in-stent technique under fluoroscopy for removal of embedded esophageal stent

Background: Treatment of complications after esophageal stent placement and methods for removal of stents need to be improved. The purpose of this study was to evaluate the safety and efficacy of stent-in-stent (SIS) removal of esophageal stent under fluoroscopy.Methods: This study retrospectively analyzed the clinical data of consecutive patients undergoing esophageal stent removal by SIS under fluoroscopy. Under awake condition, local anesthesia, and fluoroscopic monitoring, a second esophageal stent was placed in the first esophageal stent. Four weeks later, both esophageal stents were removed by the SIS technique under fluoroscopy.Results: A total of 12 patients were treated by the SIS removal technique. In 10 patients, the first esophageal stent was easily removed by the SIS method; in the other 2 patients, stent fracture occurred, and some residual nitinol wire had to be removed endoscopically. No serious complications occurred in any patient.Conclusions: The SIS removal technique appears to be a safe and effective method for removal of embedded esophageal metallic stents.

MRS-measured Glutamate versus GABA reflects excitatory versus inhibitory neural activities in awake mice

To assess if magnetic resonance spectroscopy (MRS)-measured Glutamate (Glu) and GABA reflect excitatory and inhibitory neural activities, respectively, we conducted MRS measurements along with two-photon mesoscopic imaging of calcium signals in excitatory and inhibitory neurons of living, unanesthetized mice. For monitoring stimulus-driven activations of a brain region, MRS signals and mesoscopic neural activities were measured during two consecutive sessions of 15-min prolonged sensory stimulations. In the first session, putative excitatory neuronal activities were increased, while inhibitory neuronal activities remained at the baseline level. In the second half, while excitatory neuronal activities remained elevated, inhibitory neuronal activities were significantly enhanced. We also assessed regional neurochemical and functional statuses related to spontaneous neural firing by measuring MRS signals and neuronal activities in a mouse model of Dravet syndrome under a resting condition. Mesoscopic assessments showed that activities of inhibitory neurons in the cortex were diminished relative to wild-type mice in contrast to spared activities of excitatory neurons. Consistent with these observations, the Dravet model exhibited lower concentrations of GABA than wild-type controls. Collectively, the current investigations demonstrate that the MRS-measured Glu and GABA can reflect spontaneous and stimulated activities of neurons producing and releasing these neurotransmitters in an awake condition.

Topological Analysis of Differential Effects of Ketamine and Propofol Anesthesia on Brain Dynamics

Research into the neural correlates of consciousness has found that the vividness and complexity of conscious experience is related to the structure of brain dynamics, and that alterations to consciousness track changes in temporal evolution of brain states. Despite inducing externally similar states, propofol and ketamine produce different subjective states of consciousness: here we explore the different effects of these two anaesthetics on the structure of dynamical attractors reconstructed from electrophysiological activity recorded from cerebral cortex of two non-human primates. We used two different methods of attractor reconstruction: the first embeds the recordings in a continuous high-dimensional manifold on which we use topological data analysis to infer the presence (or absence) of higher-order dynamics. The second reconstruction, an ordinal partition network embedding, allows us to create a discrete state-transition network approximation of a continuous attractor, which is amenable to information-theoretic analysis and contains rich information about state-transition dynamics. We find that the awake condition generally had the “richest” structure, with the widest repertoire of available states, the presence of pronounced higher-order structures, and the least deterministic dynamics. In contrast, the propofol condition had the most dissimilar dynamics to normal consciousness, transitioning to a more impoverished, constrained, low-structure regime. The ketamine condition, interestingly, seemed to combine aspects of both: while it was generally less complex than the awake condition, it remained well above propofol in almost all measures. These results may provides insights into how consciousness can persist under the influence of ketamine and the battery of measures used provides deeper and more comprehensive insights than what is typically gained by using point-measures of complexity.

Motor axon excitability measures in the rat tail are the same awake or anaesthetized using sodium pentobarbital

BackgroundNerve excitability tests in sciatic motor axons are sensitive to anaesthetic choice. Results using ketamine/xylazine (KX) are different from those using sodium pentobarbital (SP). It is not clear which results are most similar to the awake condition, though results using SP appear more similar to human results.MethodsNerve excitability in tail motor axons was tested in 8 adult female rats with a chronic sacral spinal cord injury. These animals have no behavioural response to electrical stimulation of the tail and were tested awake and then anaesthetized using SP.ResultsThe nerve excitability test results in the awake condition were indistinguishable from the results when the same rats were anaesthetized with sodium pentobarbital. Summary plots of the test results overlap within the boundaries of the standard error and paired t-tests on the 42 discrete measures generated by nerve excitability testing yielded no significant differences (after Bonferroni correction for multiple comparisons).ConclusionsNerve excitability test results in rat motor axons are the same whether the animals are awake or anesthetized using sodium pentobarbital.

Narcolepsy

A.M. is a 19 years old university student without any previous illness. During the fourth year of high school, episodes of motor paralysis began to occur during awakening when she is conscious, but she needs a few minutes to start to move. The episodes are manifested a couple of times monthly. Simultaneously, but rarely, there are hypnagogic hallucinations such as sound and fear in a semi awake condition and she cannot react. Practically, last three years she has attacks of irresistible sleepiness, especially when she feels comfortable. She falls asleep during lectures or when she writes a message. She sleeps for a short time during writing and that refreshes her. An 77 year-old man repeatedly experienced what he described as occasional “trance-like” states accompanied by drowsiness for about 9 years after he experienced ischemic stroke. These became increasingly frequent, finally reaching 3-5 times daily. In addition, he experienced sudden “drop attacks” during the previous 3 years. During that time, he did not receive a proper diagnosis or treatment despite several hospitalizations. Initially he was treated for epilepsy before receiving a proper diagnosis of narcolepsy.