2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade: A Report by the American Society of Anesthesiologists Task Force on Neuromuscular Blockade.

These practice guidelines provide evidence-based recommendations on the management of neuromuscular monitoring and antagonism of neuromuscular blocking agents during and after general anesthesia. The guidance focuses primarily on the type and site of monitoring and the process of antagonizing neuromuscular blockade to reduce residual neuromuscular blockade.

A Beautiful Friendship-and a Lesson about Friends and Colleagues: A Classic Partnership Revisited.

David Warner, M.D., and Michael Todd, M.D., first met in 1985. They began working together at the University of Iowa (Iowa City, Iowa) a year later with a shared interest in both laboratory and clinical neuroscience-and in the operative care of neurosurgical patients. That collaboration has now lasted for 35 yr, resulting in more than 70 joint publications. More importantly, they have had the privilege of working together with close to 1,000 colleagues from around the world, in a dozen medical specialties. Their careers are an example of what can be accomplished by friendship, mutual commitment, persistence, and a willingness to join with others.

The Evolution, Current Value, and Future of the American Society of Anesthesiologists Physical Status Classification System.

The American Society of Anesthesiologists (ASA) Physical Status classification system celebrates its 80th anniversary in 2021. Its simplicity represents its greatest strength as well as a limitation in a world of comprehensive multisystem tools. It was developed for statistical purposes and not as a surgical risk predictor. However, since it correlates well with multiple outcomes, it is widely used-appropriately or not-for risk prediction and many other purposes. It is timely to review the history and development of the system. The authors describe the controversies surrounding the ASA Physical Status classification, including the problems of interrater reliability and its limitations as a risk predictor. Last, the authors reflect on the current status and potential future of the ASA Physical Status system.

Consensus Statement on Perioperative Use of Neuromuscular Monitoring.

A panel of clinician scientists with expertise in neuromuscular blockade (NMB) monitoring was convened with a charge to prepare a consensus statement on indications for and proper use of such monitors. The aims of this article are to: (a) provide the rationale and scientific basis for the use of quantitative NMB monitoring; (b) offer a set of recommendations for quantitative NMB monitoring standards; (c) specify educational goals; and (d) propose training recommendations to ensure proper neuromuscular monitoring and management. The panel believes that whenever a neuromuscular blocker is administered, neuromuscular function must be monitored by observing the evoked muscular response to peripheral nerve stimulation. Ideally, this should be done at the hand muscles (not the facial muscles) with a quantitative (objective) monitor. Objective monitoring (documentation of train-of-four ratio ≥0.90) is the only method of assuring that satisfactory recovery of neuromuscular function has taken place. The panel also recommends that subjective evaluation of the responses to train-of-four stimulation (when using a peripheral nerve stimulator) or clinical tests of recovery from NMB (such as the 5-second head lift) should be abandoned in favor of objective monitoring. During an interim period for establishing these recommendations, if only a peripheral nerve stimulator is available, its use should be mandatory in any patient receiving a neuromuscular blocking drug. The panel acknowledges that publishing this statement per se will not result in its spontaneous acceptance, adherence to its recommendations, or change in routine practice. Implementation of objective monitoring will likely require professional societies and anesthesia department leadership to champion its use to change anesthesia practitioner behavior.

Neuromonitoring in the ambulatory anesthesia setting: a pro-con discussion.

PURPOSE OF REVIEW: Various neurologically focused monitoring modalities such as processed electroencephalography (pEEG), tissue/brain oxygenation monitors (SbO2), and even somatosensory evoked responses have been suggested as having the potential to improve the well tolerated and effective delivery of care in the setting of outpatient surgery. The present article will discuss the pros and cons of such monitors in this environment. RECENT FINDINGS: There is a paucity of evidence from rigorous, well designed clinical trials demonstrating that the routine use of any neuromonitoring technique in an ambulatory surgery setting leads to meaningful cost savings or a reduction in morbidity or mortality. SUMMARY: The use of advanced neuromonitoring techniques (primarily pEEG) may be considered reasonable in two instances: for the prevention of intraoperative awareness during the administration of total intravenous anesthesia coupled with the use of a neuromuscular blocking drug, and for the prevention of relative drug overdose (and possibly postoperative delirium) in the elderly.

Electrocorticographic delineation of human auditory cortical fields based on effects of propofol anesthesia.

The functional organization of human auditory cortex remains incompletely characterized. While the posteromedial two thirds of Heschl's gyrus (HG) is generally considered to be part of core auditory cortex, additional subdivisions of HG remain speculative. To further delineate the hierarchical organization of human auditory cortex, we investigated regional heterogeneity in the modulation of auditory cortical responses under varying depths of anesthesia induced by propofol. Non-invasive studies have shown that propofol differentially affects auditory cortical activity, with a greater impact on non-core areas. Subjects were neurosurgical patients undergoing removal of intracranial electrodes placed to identify epileptic foci. Stimuli were 50Hz click trains, presented continuously during an awake baseline period, and subsequently, while propofol infusion was incrementally titrated to induce general anesthesia. Electrocorticographic recordings were made with depth electrodes implanted in HG and subdural grid electrodes implanted over superior temporal gyrus (STG). Depth of anesthesia was monitored using spectral entropy. Averaged evoked potentials (AEPs), frequency-following responses (FFRs) and high gamma (70-150Hz) event-related band power were used to characterize auditory cortical activity. Based on the changes in AEPs and FFRs during the induction of anesthesia, posteromedial HG could be divided into two subdivisions. In the most posteromedial aspect of the gyrus, the earliest AEP deflections were preserved and FFRs increased during induction. In contrast, the remainder of the posteromedial HG exhibited attenuation of both the AEP and the FFR. The anterolateral HG exhibited weaker activation characterized by broad, low-voltage AEPs and the absence of FFRs. Lateral STG exhibited limited activation by click trains, and FFRs there diminished during induction. Sustained high gamma activity was attenuated in the most posteromedial portion of HG, and was absent in all other regions. These differential patterns of auditory cortical activity during the induction of anesthesia may serve as useful physiological markers for field delineation. In this study, the posteromedial HG could be parcellated into at least two subdivisions. Preservation of the earliest AEP deflections and FFRs in the posteromedial HG likely reflects the persistence of feedforward synaptic activity generated by inputs from subcortical auditory pathways, including the medial geniculate nucleus.

Prolonged Operative Time to Extubation Is Not a Useful Metric for Comparing the Performance of Individual Anesthesia Providers.

BACKGROUND: One anesthesiologist performance metric is the incidence of "prolonged" (15 min or longer after dressing complete) times to extubation. The authors used several methods to identify the performance outliers and assess whether targeting these outliers for reduction could improve operating room workflow. METHODS: Time to extubation data were retrieved for 27,757 anesthetics and 81 faculty anesthesiologists. Provider-specific incidences of prolonged extubation were assessed by using unadjusted frequentist statistics and a Bayesian model adjusted for prone positioning, American Society of Anesthesiologist's base units, and case duration. RESULTS: 20.31% of extubations were "prolonged," and 40% of anesthesiologists were identified as outliers using a frequentist approach, that is, incidence greater than upper 95% CI (20.71%). With an adjusted Bayesian model, only one anesthesiologist was deemed an outlier. If an average anesthesiologist performed all extubations, the incidence of prolonged extubations would change negligibly (to 20.67%). If the anesthesiologist with the highest incidence of prolonged extubations was replaced with an average anesthesiologist, the change was also negligible (20.01%). Variability among anesthesiologists in the incidence of prolonged extubations was significantly less than among other providers. CONCLUSIONS: Bayesian methodology with covariate adjustment is better suited to performance monitoring than an unadjusted, nonhierarchical frequentist approach because it is less likely to identify individuals spuriously as outliers. Targeting outliers in an effort to alter operating room activities is unlikely to have an operational impact (although monitoring may serve other purposes). If change is deemed necessary, it must be made by improving the average behavior of everyone and by focusing on anesthesia providers rather than on faculty.