Changes in Intrinsic Connectivity Networks Topology Across Levels of Dexmedetomidine-Induced Alteration of Consciousness.

BACKGROUND: Human consciousness is generally thought to emerge from the activity of intrinsic connectivity networks (resting-state networks [RSNs]) of the brain, which have topological characteristics including, among others, graph strength and efficiency. So far, most functional brain imaging studies in anesthetized subjects have compared wakefulness and unresponsiveness, a state considered as corresponding to unconsciousness. Sedation and general anesthesia not only produce unconsciousness but also phenomenological states of preserved mental content and perception of the environment (connected consciousness), and preserved mental content but no perception of the environment (disconnected consciousness). Unresponsiveness may be seen during unconsciousness, but also during disconnectedness. Deep dexmedetomidine sedation is frequently a state of disconnected consciousness. In this study, we were interested in characterizing the RSN topology changes across 4 different and steady-state levels of dexmedetomidine-induced alteration of consciousness, namely baseline (Awake, drug-free state), Mild sedation (drowsy, still responding), Deep sedation (unresponsive), and Recovery, with a focus on changes occurring between a connected consciousness state and an unresponsiveness state. METHODS: A functional magnetic resonance imaging database acquired in 14 healthy volunteers receiving dexmedetomidine sedation was analyzed using a method combining independent component analysis and graph theory, specifically looking at changes in connectivity strength and efficiency occurring during the 4 above-mentioned dexmedetomidine-induced altered consciousness states. RESULTS: Dexmedetomidine sedation preserves RSN architecture. Unresponsiveness during dexmedetomidine sedation is mainly characterized by a between-networks graph strength alteration and within-network efficiency alteration of lower-order sensory RSNs, while graph strength and efficiency in higher-order RSNs are relatively preserved. CONCLUSIONS: The differential dexmedetomidine-induced RSN topological changes evidenced in this study may be the signature of inadequate processing of sensory information by lower-order RSNs, and of altered communication between lower-order and higher-order networks, while the latter remain functional. If replicated in an experimental paradigm distinguishing, in unresponsive subjects, disconnected consciousness from unconsciousness, such changes would sustain the hypothesis that disconnected consciousness arises from altered information handling by lower-order sensory networks and altered communication between lower-order and higher-order networks, while the preservation of higher-order networks functioning allows for an internally generated mental content (or dream).

The effects of intrathecal morphine on urinary bladder function and recovery in patients having a cesarean delivery - A randomized clinical trial.

INTRODUCTION: Spinal anesthesia with intrathecal morphine (ITM) is a common anesthesia technique for cesarean delivery. The hypothesis was that the addition of ITM will delay micturition in women undergoing cesarean delivery. METHODS: Fifty-six ASA physical status I and II women scheduled to undergo elective cesarean delivery under spinal anesthesia were randomized to the PSM group (50 mg prilocaine + 2.5 mcg sufentanil + 100 mcg morphine; n = 30) or PS group (50 mg prilocaine + 2.5 mcg sufentanil; n = 24). The patients in the PS group received a bilateral transverse abdominal plane (TAP) block. The primary outcome was the effect of ITM on the time to micturition and the secondary outcome was the need for bladder re-catheterization. RESULTS: The time to first urge to urinate (8 [6-10] hours in the PSM group versus 6 [4-6] hours in the PS group) and the time to first micturition (10 [8-12] hours in the PSM group versus 6 [6-8] hours in the PS group) were significantly (p < 0.001) prolonged in the PSM group. Two patients in the PSM group met the 800 mL criterium for urinary catheterization after 6 and 8 h respectively. CONCLUSION: This study is the first randomized trial to demonstrate that the addition of ITM to the standardized mixture of prilocaine and sufentanil significantly delayed micturition.

Cardiac Biomarkers and Prediction of Early Outcome After Heart Valve Surgery: A Prospective Observational Study.

OBJECTIVES: Circulating cardiac biomarkers may improve the prediction of long-term outcomes after cardiac surgery. The authors sought to assess if cardiac biomarkers also help better predict short-term morbidity. DESIGN: Prospective observational study. SETTING: Single academic hospital. PARTICIPANTS: A total of 250 patients undergoing aortic or mitral valve surgery with or without associated coronary artery bypass grafts. INTERVENTION: None MEASUREMENT AND MAIN RESULTS: Relationships between preoperative plasma concentrations of four cardiac biomarkers (sST2, Galectin-3, GDF-15, and NT-proBNP) and postoperative outcome were assessed using logistic regressions and Cox proportional hazards models. The primary outcome was a composite of 30-day mortality, an inotropic support longer than 48 hours and an initial length of stay in the intensive care >five days. Secondary outcome measures were postoperative acute kidney injury, inotropic support duration, lengths of intensive care unit and hospital stays, and 30-day and one-year mortality. No association was observed between any of the four cardiac biomarkers and the primary outcome. The preoperative levels of Galectin-3 (hazard ratio = 1.2; p < 0.001) and sST2 (hazard ratio = 1.01, p < 0.001) were significantly associated with one-year survival, and their addition to the EuroSCORE II significantly improved the prediction of one-year mortality (p < 0.001). Similarly, Galectin-3 was associated with postoperative acute kidney injury (odds ratio = 1.15, p = 0.001) and improved the prediction of this complication when added to the EuroSCORE II (p = 0.002). CONCLUSIONS: These results suggested that the ability of cardiac biomarkers to predict short-term outcome after cardiac surgery, though of interest, appears limited. Conversely, cardiac biomarkers may have the potential to refine the prediction of long-term outcome. Admittedly, all positive results were obtained on secondary outcomes and must be regarded with caution.

In situ simulation improves perceived self-efficacy of OR nurses and anaesthesiologists during COVID-19 pandemic.

Introduction: Self-efficacy is defined as people's internal beliefs about their ability to have an impact on events that affect their lives. As part of the COVID-19 pandemic, we carried out in situ simulation for anaesthesiologists and operating room (OR) nurses. Simulation was focused on the recommendations on the use of specific personal protective equipment (PPE) as well as on airway management and intubation. We hypothesised that in situ procedural simulation should increase their perceived self-efficacy. Methods: Between 16 March and 20 March 2020, 208 healthcare workers took part in in situ procedural simulation. A questionnaire was sent to participants on 21 April 2020. Six self-efficacy items related to PPE and airway manoeuvres were assessed before and after training on a Numeric Rating Scale from 0 to 10. Results: Sixty-seven participants (32%) replied to the questionnaire. The before-after comparison of the six items revealed an increase in perceived self-efficacy for each of them. A before training difference was observed between nurses, board-certified anaesthetists and trainees in anaesthesia in perceived self-efficacy for putting on (6 (3-8) vs 4.5 (2.25-6) vs 2 (0-6), p=0.007) and remove PPE (8 (5-8) vs 4.5 (3.25-6) vs 4 (1-6), p=0.009). No difference in perceived self-efficacy after training was observed between nurses, board-certified anaesthetists and trainees in anaesthesia. Conclusions: In situ simulation improves the perceived self-efficacy of OR nurses and anaesthesiologists on specific skills related to the care of patients with COVID-19.

Quadratus lumborum block: an imaging study of three approaches.

BACKGROUND AND OBJECTIVES: Different injection techniques for the quadratus lumborum (QL) block have been described. Data in human cadavers suggest that the transverse oblique paramedian (TOP) QL3 may reach the thoracic paravertebral space more consistently than the QL1 and QL2. However, the distribution of injectate in cadavers may differ from that in patients. Hence, we assessed the distribution of the injectate after the QL1, QL2, and TOP QL3 techniques in patients. MATERIALS AND METHODS: Thirty-four patients scheduled for abdominal surgery received QL blocks postoperatively; 26 patients received bilateral and 8 patients received unilateral blocks. Block injections were randomly allocated to QL1, QL2, or TOP QL3 techniques (20 blocks per each technique). The injections consisted of 18 mL of ropivacaine 0.375% with 2 mL of radiopaque contrast, injected lateral or posterior to the QL muscle for the QL1 and QL2 techniques, respectively. For the TOP QL3, the injection was into the plane between the QL and psoas muscles, proximal to the L2 transverse process. Two reviewers, blinded to the allocation, reviewed three-dimensional computed tomography (3D-CT) images to assess the distribution of injectate. RESULTS AND DISCUSSION: The QL1 block spread in the transversus abdominis plane (TAP), QL2 in the TAP, and posterior aspect of the QL muscle, whereas TOP QL3 spread consistently in the anterior aspect of the QL muscle with occasional spread to the lumbar and thoracic paravertebral areas. CONCLUSIONS: The spread of injectate after QL1, QL2, and QL3 blocks, resulted in different distribution patterns, primarily in the area of injection. The TOP QL3 did not result in consistent interfascial spread toward the thoracic paravertebral space.

A fast and general method to empirically estimate the complexity of brain responses to transcranial and intracranial stimulations.

BACKGROUND: The Perturbational Complexity Index (PCI) was recently introduced to assess the capacity of thalamocortical circuits to engage in complex patterns of causal interactions. While showing high accuracy in detecting consciousness in brain-injured patients, PCI depends on elaborate experimental setups and offline processing, and has restricted applicability to other types of brain signals beyond transcranial magnetic stimulation and high-density EEG (TMS/hd-EEG) recordings. OBJECTIVE: We aim to address these limitations by introducing PCIST, a fast method for estimating perturbational complexity of any given brain response signal. METHODS: PCIST is based on dimensionality reduction and state transitions (ST) quantification of evoked potentials. The index was validated on a large dataset of TMS/hd-EEG recordings obtained from 108 healthy subjects and 108 brain-injured patients, and tested on sparse intracranial recordings (SEEG) of 9 patients undergoing intracranial single-pulse electrical stimulation (SPES) during wakefulness and sleep. RESULTS: When calculated on TMS/hd-EEG potentials, PCIST performed with the same accuracy as the original PCI, while improving on the previous method by being computed in less than a second and requiring a simpler set-up. In SPES/SEEG signals, the index was able to quantify a systematic reduction of intracranial complexity during sleep, confirming the occurrence of state-dependent changes in the effective connectivity of thalamocortical circuits, as originally assessed through TMS/hd-EEG. CONCLUSIONS: PCIST represents a fundamental advancement towards the implementation of a reliable and fast clinical tool for the bedside assessment of consciousness as well as a general measure to explore the neuronal mechanisms of loss/recovery of brain complexity across scales and models.

The spectral exponent of the resting EEG indexes the presence of consciousness during unresponsiveness induced by propofol, xenon, and ketamine.

Despite the absence of responsiveness during anesthesia, conscious experience may persist. However, reliable, easily acquirable and interpretable neurophysiological markers of the presence of consciousness in unresponsive states are still missing. A promising marker is based on the decay-rate of the power spectral density (PSD) of the resting EEG. We acquired resting electroencephalogram (EEG) in three groups of healthy participants (n = 5 each), before and during anesthesia induced by either xenon, propofol or ketamine. Dosage of each anesthetic agent was tailored to yield unresponsiveness (Ramsay score = 6). Delayed subjective reports assessed whether conscious experience was present ('Conscious report') or absent/inaccessible to recall ('No Report'). We estimated the decay of the PSD of the resting EEG-after removing oscillatory peaks-via the spectral exponent ß, for a broad band (1-40 Hz) and narrower sub-bands (1-20 Hz, 20-40 Hz). Within-subject anesthetic changes in ß were assessed. Furthermore, based on ß, 'Conscious report' states were discriminated against 'no report' states. Finally, we evaluated the correlation of the resting spectral exponent with a recently proposed index of consciousness, the Perturbational Complexity Index (PCI), derived from a previous TMS-EEG study. The spectral exponent of the resting EEG discriminated states in which consciousness was present (wakefulness, ketamine) from states where consciousness was reduced or abolished (xenon, propofol). Loss of consciousness substantially decreased the (negative) broad-band spectral exponent in each subject undergoing xenon or propofol anesthesia-indexing an overall steeper PSD decay. Conversely, ketamine displayed an overall PSD decay similar to that of wakefulness-consistent with the preservation of consciousness-yet it showed a flattening of the decay in the high-frequencies (20-40 Hz)-consistent with its specific mechanism of action. The spectral exponent was highly correlated to PCI, corroborating its interpretation as a marker of the presence of consciousness. A steeper PSD of the resting EEG reliably indexed unconsciousness in anesthesia, beyond sheer unresponsiveness.

The Edmonton Frail Scale Improves the Prediction of 30-Day Mortality in Elderly Patients Undergoing Cardiac Surgery: A Prospective Observational Study.

OBJECTIVES: To investigate whether the Edmonton Frail Scale (EFS), a multidimensional frailty assessment tool, improves the prediction of 30-day or in-hospital mortality over the use of the European System for Cardiac Outcome Risk Evaluation (EuroSCORE) II alone. DESIGN: Single-center prospective observational study. SETTING: University hospital. PARTICIPANTS: Patients aged 75 years or older undergoing cardiac surgery between February 2014 and May 2017. INTERVENTION: No intervention was performed. The EFS was administered the day before surgery. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was 30-day or in-hospital mortality. Secondary endpoints were times to discharge from the intensive care unit (ICU) and from the hospital, discharge to a health care facility, and ability to return home by postoperative day 30. The EFS had a good discriminative ability for 30-day mortality (area under the receiver operating characteristic curve = 0.69; 95% confidence interval [CI], 0.56-0.82). Adding frailty, defined by an EFS ≥8, to the EuroSCORE II significantly improved the prediction of 30-day (p = 0.04) mortality. The integrated discrimination index was 0.03 (95% CI, 0.01-0.06, p = 0.01), meaning that the difference in predicted risk between patients who died and those who survived increased by 3% due to the addition of frailty determined by the EFS to the EuroSCORE II. Frailty also was associated significantly with a decreased cumulative probability of discharge from the ICU (p = 0.02) and an increased incidence of discharge to a health care facility (p = 0.01). CONCLUSION: The EFS has a good predictive ability for 30-day mortality after cardiac surgery in elderly patients and improves the prediction of 30-day mortality over the use of the EuroSCORE II.

Evoked Alpha Power is Reduced in Disconnected Consciousness During Sleep and Anesthesia.

Sleep and anesthesia entail alterations in conscious experience. Conscious experience may be absent (unconsciousness) or take the form of dreaming, a state in which sensory stimuli are not incorporated into conscious experience (disconnected consciousness). Recent work has identified features of cortical activity that distinguish conscious from unconscious states; however, less is known about how cortical activity differs between disconnected states and normal wakefulness. We employed transcranial magnetic stimulation-electroencephalography (TMS-EEG) over parietal regions across states of anesthesia and sleep to assess whether evoked oscillatory activity differed in disconnected states. We hypothesized that alpha activity, which may regulate perception of sensory stimuli, is altered in the disconnected states of rapid eye movement (REM) sleep and ketamine anesthesia. Compared to wakefulness, evoked alpha power (8-12 Hz) was decreased during disconnected consciousness. In contrast, in unconscious states of propofol anesthesia and non-REM (NREM) sleep, evoked low-gamma power (30-40 Hz) was decreased compared to wakefulness or states of disconnected consciousness. These findings were confirmed in subjects in which dream reports were obtained following serial awakenings from NREM sleep. By examining signatures of evoked cortical activity across conscious states, we identified novel evidence that suppression of evoked alpha activity may represent a promising marker of sensory disconnection.

Comparison of clinical scores in their ability to detect hypoxemic severe OSA patients.

BACKGROUND: Severe obstructive sleep apnea (sOSA) and preoperative hypoxemia are risk factors of postoperative complications. Patients exhibiting the combination of both factors are probably at higher perioperative risk. Four scores (STOP-Bang, P-SAP, OSA50, and DES-OSA) are currently used to detect OSA patients preoperatively. This study compared their ability to specifically detect hypoxemic sOSA patients. METHODS: One hundred and fifty-nine patients scheduled for an overnight polysomnography (PSG) were prospectively enrolled. The ability of the four scores to predict the occurrence of hypoxemic episodes in sOSA patients was compared using sensitivity (Se), specificity (Sp), Youden Index, Cohen kappa coefficient, and the area under ROC curve (AUROC) analyses. RESULTS: OSA50 elicited the highest Se [95% CI] at detecting hypoxemic sOSA patients (1 [0.89-1]) and was significantly more sensitive than STOP-Bang in that respect. DES-OSA was significantly more specific (0.58 [0.49-0.66]) than the three other scores. The Youden Index of DES-OSA (1.45 [1.33-1.58]) was significantly higher than those of STOP-Bang, P-SAP, and OSA50. The AUROC of DES-OSA (0.8 [0.71-0.89]) was significantly the largest. The highest Kappa value was obtained for DES-OSA (0.33 [0.21-0.45]) and was significantly higher than those of STOP-Bang, and OSA50. CONCLUSIONS: In our population, DES-OSA appears to be more effective than the three other scores to specifically detect hypoxemic sOSA patients. However prospective studies are needed to confirm these findings in a perioperative setting. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT02050685.

Low Cardiac Output Syndrome After Adult Cardiac Surgery: Predictive Value of Peak Systolic Global Longitudinal Strain.

BACKGROUND: Peak systolic global longitudinal strain (GLS) is increasingly used to quantify left ventricular systolic function. The primary objective of this study was to assess whether GLS obtained during intraoperative transesophageal echocardiogram, performed before cardiopulmonary bypass, improves the prediction of postoperative low cardiac output syndrome (LCOS) after adult cardiac surgery. METHODS: GLS from 275 patients undergoing on-pump cardiac surgery was calculated retrospectively using two-dimensional- speckle tracking echocardiography (aCMQ module from Qlab software version 10.5, Philips Medical, Brussels, Belgium). LCOS was defined as the need for inotropic or mechanical circulatory support for >24 hours postoperatively. Patient and procedure characteristics associated with LCOS at the univariable level (P ≤ .05) were entered into a forward stepwise logistic regression to create a first predictive model. A second model was created by adding GLS. The 2 models were compared using the likelihood-ratio test, the area under the receiver operating characteristic (ROC) curve, and the integrated discrimination index. The optimal cutoff value of GLS associated with LCOS was determined by maximizing the Youden index of the ROC curve. Secondary outcomes included time until complete weaning from inotropes, discharge from the intensive care unit and from the hospital, and 30-day mortality. RESULTS: GLS was significantly associated with LCOS (P < .001) at the univariable level. Predictors of LCOS retained in the first model were cardiopulmonary bypass duration, decreased left ventricular ejection fraction, mitral valve surgery, and New York Heart Association functional class III or IV. Adding the GLS value improved the prediction of LCOS (P = .02). However, the area under the ROC curve did not differ between the 2 models (0.83; 95% confidence interval [CI], 0.77-0.99 vs 0.84; 95% CI, 0.79-0.90; P = .15). The integrated discrimination index associated with addition of GLS was 0.02 (P = .046), meaning that the difference in predicted risk between patients with and without LCOS increased by 2% after adding GLS. A GLS cutoff value of -17% (95% CI, -18.8% to -15.3%) was found to best identify LCOS. After adjusting for covariates included in model 1, a lower GLS value was significantly associated with a lower cumulative probability of weaning from inotropes postoperatively (hazard ratio, 0.90; 95% CI, 0.82-0.97; P = .01). No association was found between GLS and other secondary outcome measures. CONCLUSIONS: GLS is an independent predictor of LCOS after on-pump cardiac surgery. Its incremental value over other established risk factors for postoperative LCOS is, however, limited.

Quality of life at home and satisfaction of patients after enhanced recovery protocol for colorectal surgery.

BACKGROUND: Quality of life of patients at home after an enhanced recovery protocol (ERP) for surgery has been least studied especially in elderly patients. METHODS: Our first 41 patients entered in the colorectal GRACE database were interviewed through telephone about their postoperative stress, fatigue, pain, difficulty in feeding, home autonomy, and satisfaction. We compared the responses of the elderly patients (>70 years, n = 19) with those of the younger patients. RESULTS: The time between the surgery and the questionnaire was 79 ± 48 days. Early return was experienced as stressful by ±20% of the patients. Fatigue and pain were low (respectively: simple numerical scale [SNS] = 4.2 ± 3.2 and 2.5 ± 2.9). When present, pain was relieved by the prescribed treatment. One-third of the patients described some difficulty in feeding. Fifty percent of the patients felt completely autonomous when returned at home, 80% attributed the rapid recovery of autonomy to the ERP. Finally, 87% were globally satisfied (SNS: 8.5 ± 1.0). The characteristics of the 'elderly' group (77 ± 6 years) and their questionnaire responses were similar to those of the younger patients. CONCLUSIONS: Despite some limitations (retrospective, different time between surgery and the telephone survey), our study suggests that quality of life at home after ERP for colorectal surgery is very satisfactory for over 80% of patients. Furthermore, this study confirms that elderly patients benefit from an ERP for colorectal surgery like younger patients.

Sedation of Patients With Disorders of Consciousness During Neuroimaging: Effects on Resting State Functional Brain Connectivity.

BACKGROUND: To reduce head movement during resting state functional magnetic resonance imaging, post-coma patients with disorders of consciousness (DOC) are frequently sedated with propofol. However, little is known about the effects of this sedation on the brain connectivity patterns in the damaged brain essential for differential diagnosis. In this study, we aimed to assess these effects. METHODS: Using resting state functional magnetic resonance imaging 3T data obtained over several years of scanning patients for diagnostic and research purposes, we employed a seed-based approach to examine resting state connectivity in higher-order (default mode, bilateral external control, and salience) and lower-order (auditory, sensorimotor, and visual) resting state networks and connectivity with the thalamus, in 20 healthy unsedated controls, 8 unsedated patients with DOC, and 8 patients with DOC sedated with propofol. The DOC groups were matched for age at onset, etiology, time spent in DOC, diagnosis, standardized behavioral assessment scores, movement intensities, and pattern of structural brain injury (as assessed with T1-based voxel-based morphometry). RESULTS: DOC were associated with severely impaired resting state network connectivity in all but the visual network. Thalamic connectivity to higher-order network regions was also reduced. Propofol administration to patients was associated with minor further decreases in thalamic and insular connectivity. CONCLUSIONS: Our findings indicate that connectivity decreases associated with propofol sedation, involving the thalamus and insula, are relatively small compared with those already caused by DOC-associated structural brain injury. Nonetheless, given the known importance of the thalamus in brain arousal, its disruption could well reflect the diminished movement obtained in these patients. However, more research is needed on this topic to fully address the research question.

Risk factors for nocturnal hypoxemia in severe obstructive sleep apnea patients.

BACKGROUND: Severe obstructive sleep apnea (sOSA) and oxygen desaturations are both risk factors for postoperative complications. In some but not all patients, sOSA is associated with frequent oxygen desaturation episodes during sleep. The aim of this retrospective study was to identify the risk factors for exhibiting oxygen desaturation in patients with sOSA. METHODS: Records of 786 patients, mainly obese (Body Mass Index [mean+SD]=30.2+6.0 kg/m2), were analyzed. Univariate and multivariate analyzes were applied to identify predictive risk factors for oxygen desaturation. Prediction probability was used to test the association between potential risk factors (obesity, age, gender, smoking, alcohol consumption, and benzodiazepines use) and the combination of sOSA and oxygen desaturation. A P value <0.05 was considered as statistically significant. RESULTS: Univariate and multivariate analyses identified five risk factors for oxygen desaturation in the whole population: age (P<0.001), obesity (P<0.001), benzodiazepine use (P<0.001), smoking (P=0.016), and male gender (P=0.029). The same analyses applied to patients with sOSA identified two independent risk factors for oxygen desaturation: obesity (P<0.001), and benzodiazepine use (P=0.017). Obesity obtains the best prediction probability [95% CI] for the combination of sOSA and oxygen desaturation: 0.74 [0.69-0.79]. A BMI >49 kg/m2 was associated with a 50% probability of combining severe OSA and nocturnal oxygen desaturation. CONCLUSIONS: Less than 50% of patients with sOSA experience nocturnal oxygen desaturation. Obesity and daily benzodiazepine intake are independent risk factors for these patients to exhibit nocturnal oxygen desaturation. Benzodiazepine in obese patients with sOSA should, therefore, be used cautiously.

Resting-state Network-specific Breakdown of Functional Connectivity during Ketamine Alteration of Consciousness in Volunteers.

BACKGROUND: Consciousness-altering anesthetic agents disturb connectivity between brain regions composing the resting-state consciousness networks (RSNs). The default mode network (DMn), executive control network, salience network (SALn), auditory network, sensorimotor network (SMn), and visual network sustain mentation. Ketamine modifies consciousness differently from other agents, producing psychedelic dreaming and no apparent interaction with the environment. The authors used functional magnetic resonance imaging to explore ketamine-induced changes in RSNs connectivity. METHODS: Fourteen healthy volunteers received stepwise intravenous infusions of ketamine up to loss of responsiveness. Because of agitation, data from six subjects were excluded from analysis. RSNs connectivity was compared between absence of ketamine (wake state [W1]), light ketamine sedation, and ketamine-induced unresponsiveness (deep sedation [S2]). RESULTS: Increasing the depth of ketamine sedation from W1 to S2 altered DMn and SALn connectivity and suppressed the anticorrelated activity between DMn and other brain regions. During S2, DMn connectivity, particularly between the medial prefrontal cortex and the remaining network (effect size ß [95% CI]: W1 = 0.20 [0.18 to 0.22]; S2 = 0.07 [0.04 to 0.09]), and DMn anticorrelated activity (e.g., right sensory cortex: W1 = -0.07 [-0.09 to -0.04]; S2 = 0.04 [0.01 to 0.06]) were broken down. SALn connectivity was nonuniformly suppressed (e.g., left parietal operculum: W1 = 0.08 [0.06 to 0.09]; S2 = 0.05 [0.02 to 0.07]). Executive control networks, auditory network, SMn, and visual network were minimally affected. CONCLUSIONS: Ketamine induces specific changes in connectivity within and between RSNs. Breakdown of frontoparietal DMn connectivity and DMn anticorrelation and sensory and SMn connectivity preservation are common to ketamine and propofol-induced alterations of consciousness.

Interfascial Spread of Injectate After Adductor Canal Injection in Fresh Human Cadavers.

The adductor canal block has become a common analgesic technique in patients undergoing knee arthroplasty. Dispersion of local anesthetic outside the adductor canal through interfascial layers and blockade of smaller nerves that confer innervation to the knee could contribute to the analgesic efficacy of the adductor canal block. We studied the diffusion of local anesthetic mixed with dye after injection into the adductor canal in fresh human cadavers. In all 8 legs, injectate was found in the popliteal fossa in contact with the sciatic nerve and/or popliteal blood vessels. Interfascial spread patterns were identified.