Differential classification of states of consciousness using envelope- and phase-based functional connectivity

The development of sophisticated computational tools to quantify changes in the brain\u27s oscillatory dynamics across states of consciousness have included both envelope- and phase-based measures of functional connectivity (FC), but there are very few direct comparisons of these techniques using the same dataset. The goal of this study was to compare an envelope-based (i.e. Amplitude Envelope Correlation, AEC) and a phase-based (i.e. weighted Phase Lag Index, wPLI) measure of FC in their classification of states of consciousness. Nine healthy participants underwent a three-hour experimental anesthetic protocol with propofol induction and isoflurane maintenance, in which five minutes of 128-channel electroencephalography were recorded before, during, and after anesthetic-induced unconsciousness, at the following time points: Baseline; light sedation with propofol (Light Sedation); deep unconsciousness following three hours of surgical levels of anesthesia with isoflurane (Unconscious); five minutes prior to the recovery of consciousness (Pre-ROC); and three hours following the recovery of consciousness (Recovery). Support vector machine classification was applied to the source-localized EEG in the alpha (8-13 Hz) frequency band in order to investigate the ability of AEC and wPLI (separately and together) to discriminate i) the four states from Baseline; ii) Unconscious ( deep unconsciousness) vs. Pre-ROC ( light unconsciousness); and iii) responsiveness (Baseline, Light Sedation, Recovery) vs. unresponsiveness (Unconscious, Pre-ROC). AEC and wPLI yielded different patterns of global connectivity across states of consciousness, with AEC showing the strongest network connectivity during the Unconscious epoch, and wPLI showing the strongest connectivity during full consciousness (i.e., Baseline and Recovery). Both measures also demonstrated differential predictive contributions across participants and used different brain regions for classification. AEC showed higher classification accuracy overall, particularly for distinguishing anesthetic-induced unconsciousness from Baseline (83.7 ± 0.8%). AEC also showed stronger classification accuracy than wPLI when distinguishing Unconscious from Pre-ROC (i.e., deep from light unconsciousness) (AEC: 66.3 ± 1.2%; wPLI: 56.2 ± 1.3%), and when distinguishing between responsiveness and unresponsiveness (AEC: 76.0 ± 1.3%; wPLI: 63.6 ± 1.8%). Classification accuracy was not improved compared to AEC when both AEC and wPLI were combined. This analysis of source-localized EEG data demonstrates that envelope- and phase-based FC provide different information about states of consciousness but that, on a group level, AEC is better able to detect relative alterations in brain FC across levels of anesthetic-induced unconsciousness compared to wPLI

Ketamine infusion for patients receiving extracorporeal membrane oxygenation support: A case series

The use of ketamine infusion for sedation/analgesia in patients receiving extracorporeal membrane oxygenation (ECMO) therapy has not been described. The aims of this retrospective cohort study were to explore whether ketamine infusion for patients requiring ECMO therapy was associated with altered RASS scores, decreased concurrent sedative or opioid use, or with changes in vasopressor requirements.  All patients on ECMO who received ketamine infusions in addition to sedative and/or opioid infusions between December 2013 and October 2014 at Barnes-Jewish Hospital in St. Louis were retrospectively identified. Patient characteristics and process of care data were collected. A total of 26 ECMO patients receiving ketamine infusion were identified. The median (inter quartile range [range]) age was 40 years (30-52 [25-66]) with 62% male. The median starting infusion rate of ketamine was 50 mg/hr (30-50 [6-150]) and it was continued for a median duration of 9 days (4-14 [0.2-21]). Prior to ketamine, 14/26 patients were receiving vasopressor infusions to maintain hemodynamic stability. Ketamine initiation was associated with a decrease in vasopressor requirement in 11/26  patients within two hours, and 0/26 required an increase (p<0.001). All patients were receiving sedative and/or opioid infusions at the time of ketamine initiation; 9/26 had a decrease in these infusions within two hours of ketamine initiation, and 1/26 had an increase (p=0.02; odds ratio for decrease to increase = 9; 95% CI, 1.14 to 71.04). The median (IQR[range]) RASS score 24 hours before ketamine initiation was -4 (-3 to -5, [0 to -5]) and after ketamine was -4 (-3 to -4 [-1 to -5]) ( P = 0.614). Ketamine infusion can be used as an adjunctive sedative agent in patients receiving ECMO and may decrease concurrent sedative and/or opioid infusions without altering RASS scores. The hemodynamic effects of ketamine may provide the benefit of decreasing vasopressor requirements

Prevention of awareness during general anesthesia

Awareness during general anesthesia with subsequent explicit recall is a serious and frequently preventable problem that is gaining attention from clinicians and patients alike. Cost-effective interventions that increase vigilance should be implemented to decrease the likelihood of this complication

Statistics of heart failure and mechanical circulatory support in 2020

Heart failure is increasing in prevalence, with approximately 26 million patients affected worldwide. This represents a significant cause of morbidity and mortality. Statistics regarding heart failure patient age, hospitalization likelihood, and mortality differ significantly by country. Heart failure patients are typically classified by ejection fraction, with distinct phenotypes associated with reduced ejection fraction (rEF) or preserved ejection fraction (pEF). Heart failure has a significant financial impact related to hospitalization, medication, and procedural expenses. The costs of heart failure also extend to the reduced quality of life conferred by heart failure symptoms. Management of heart failure includes a variety of interventions, including mechanical circulatory support (MCS). MCS, including left ventricular assist devices (LVADs), right ventricular assist devices (RVADs) and extracorporeal membrane oxygenation (ECMO), has been a means of managing end stage heart failure. Given the relative scarcity of transplant organs, the utilization of MCS, particularly as a bridge to transplantation (BTT) has grown significantly. In this review, we discuss statistics related to heart failure and MCS. We evaluate how patients are classified and examine global trends and regional differences. We then address MCS therapies, the costs associated with heart failure, the impact of heart failure on patient quality of life, and data regarding morbidity and mortality

Study protocol for the Anesthesiology Control Tower—Feedback Alerts to Supplement Treatments (ACTFAST-3) trial: A pilot randomized controlled trial in intraoperative telemedicine [version 1; referees: 2 approved]

Background: Each year, over 300 million people undergo surgical procedures worldwide. Despite efforts to improve outcomes, postoperative morbidity and mortality are common. Many patients experience complications as a result of either medical error or failure to adhere to established clinical practice guidelines. This protocol describes a clinical trial comparing a telemedicine-based decision support system, the Anesthesiology Control Tower (ACT), with enhanced standard intraoperative care. Methods: This study is a pragmatic, comparative effectiveness trial that will randomize approximately 12,000 adult surgical patients on an operating room (OR) level to a control or to an intervention group. All OR clinicians will have access to decision support software within the OR as a part of enhanced standard intraoperative care. The ACT will monitor patients in both groups and will provide additional support to the clinicians assigned to intervention ORs. Primary outcomes include blood glucose management and temperature management. Secondary outcomes will include surrogate, clinical, and economic outcomes, such as incidence of intraoperative hypotension, postoperative respiratory compromise, acute kidney injury, delirium, and volatile anesthetic utilization. Ethics and dissemination: The ACTFAST-3 study has been approved by the Human Resource Protection Office (HRPO) at Washington University in St. Louis and is registered at clinicaltrials.gov (NCT02830126). Recruitment for this protocol began in April 2017 and will end in December 2018. Dissemination of the findings of this study will occur via presentations at academic conferences, journal publications, and educational materials

General anesthesia does not have persistent effects on attention in rodents

Background: Studies in animals have shown that general anesthesia can cause persistent spatial memory impairment, but the influence of anesthetics on other cognitive functions is unclear. This study tested whether exposure to general anesthesia without surgery caused a persistent deficit in attention in rodents.Methods: To evaluate whether anesthesia has persistent effects on attention, rats were randomized to three groups. Group A was exposed for 2 h to isoflurane anesthesia, and tested the following seven days for attentional deficits. Group B was used as a control and received room air before attentional testing. Since there is some evidence that a subanesthetic dose of ketamine can improve cognition and reduce disorders of attention after surgery, rats in group C were exposed to isoflurane anesthesia in combination with a ketamine injection before cognitive assessment. Attention was measured in rats using the 5-Choice Serial Reaction Time Task, for which animals were trained to respond with a nose poke on a touchscreen to a brief, unpredictable visual stimulus in one of five possible grid locations to receive a food reward. Attention was analyzed as % accuracy, % omission, and premature responses.Results: Evaluating acute attention by comparing baseline values with data from the day after intervention did not reveal any differences in attentional measurements. No significant differences were seen in % accuracy, % omission, and premature responses for the three groups tested for 7 consecutive days.Conclusion: These data in healthy rodents suggest that general anesthesia without surgery has no persistent effect on attention and the addition of ketamine does not alter the outcome