A Pilot Investigation Evaluating Relative Changes in Fronto-Occipital Alpha and Beta Spectral Power as Measurement of Anesthesia Hypnotic Depth.

BACKGROUND: Other than clinical observation of a patient's vegetative response to nociception, monitoring the hypnotic component of general anesthesia (GA) and unconsciousness relies on electroencephalography (EEG)-based indices. These indices exclusively based on frontal EEG activity neglect an important observation. One of the main hallmarks of transitions from wakefulness to GA is a shift in alpha oscillations (7.5-12.5 Hz activity) from occipital brain regions toward anterior brain regions ("alpha anteriorization"). Monitoring the degree of this alpha anteriorization may help to guide induction and maintenance of hypnotic depth and prevent intraoperative awareness. However, the occipital region of the brain is completely disregarded and occipital alpha as characteristic of wakefulness and its posterior-to-anterior shift during induction are missed. Here, we propose an application of Narcotrend's reduced power alpha beta (RPAB) index, originally developed to monitor differences in hemispheric perfusion, for determining the ratio of alpha and beta activity in the anterior-posterior axis. METHODS: Perioperative EEG data of 32 patients undergoing GA in the ophthalmic surgery department of Bern University Hospital were retrospectively analyzed. EEG was recorded with the Narcotrend® monitor using a frontal (Fp1-Fp2) and a posterior (T9-Oz) bipolar derivation with reference electrode over A2. The RPAB index was computed between both bipolar signals, defining the fronto-occipital RPAB (FO-RPAB). FO-RPAB was analyzed during wakefulness, GA maintenance, and emergence, as well as before and after the intraoperative administration of a ketamine bolus. FO-RPAB was compared with a classical quantitative EEG measure-the spectral edge frequency 95% (SEF-95). RESULTS: A significant shift of the FO-RPAB was observed during both induction of and emergence from GA ( P < .001). Interestingly, the additional administration of ketamine during GA did not lead to a significant change in FO-RPAB ( P = 0.81). In contrast, a significant increase in the SEF-95 in the frontal channel was observed during the 10-minute period after ketamine administration ( P < .001). CONCLUSIONS: FO-RPAB appears to qualify as a marker of unconsciousness, reflecting physiological fronto-occipital activity differences during GA. In contrast to frontal SEF-95, it is not disturbed by additional administration of ketamine for analgesia.

The Effect of Perioperative Auditory Stimulation with Music on Procedural Pain: A Narrative Review.

PURPOSE OF REVIEW: Music therapy has seen increasing applications in various medical fields over the last decades. In the vast range of possibilities through which music can relieve suffering, there is a risk that-given its efficacy-the physiological underpinnings are too little understood. This review provides evidence-based neurobiological concepts for the use of music in perioperative pain management. RECENT FINDINGS: The current neuroscientific literature shows a significant convergence of the pain matrix and neuronal networks of pleasure triggered by music. These functions seem to antagonize each other and can thus be brought to fruition in pain therapy. The encouraging results of fMRI and EEG studies still await full translation of this top-down modulating mechanism into broad clinical practice. We embed the current clinical literature in a neurobiological framework. This involves touching on Bayesian "predictive coding" pain theories in broad strokes and outlining functional units in the nociception and pain matrix. These will help to understand clinical findings in the literature summarized in the second part of the review. There are opportunities for perioperative practitioners, including anesthesiologists treating acute pain and anxiety in emergency and perioperative situations, where music could help bring relieve to patients.

Analgesia for the Bayesian Brain: How Predictive Coding Offers Insights Into the Subjectivity of Pain.

PURPOSE OF REVIEW: In order to better treat pain, we must understand its architecture and pathways. Many modulatory approaches of pain management strategies are only poorly understood. This review aims to provide a theoretical framework of pain perception and modulation in order to assist in clinical understanding and research of analgesia and anesthesia. RECENT FINDINGS: Limitations of traditional models for pain have driven the application of new data analysis models. The Bayesian principle of predictive coding has found increasing application in neuroscientific research, providing a promising theoretical background for the principles of consciousness and perception. It can be applied to the subjective perception of pain. Pain perception can be viewed as a continuous hierarchical process of bottom-up sensory inputs colliding with top-down modulations and prior experiences, involving multiple cortical and subcortical hubs of the pain matrix. Predictive coding provides a mathematical model for this interplay.

The nuts and bolts of multimodal anaesthesia in the 21st century: a primer for clinicians.

PURPOSE OF REVIEW: This review article explores the application of multimodal anaesthesia in general anaesthesia, particularly in conjunction with locoregional anaesthesia, specifically focusing on the importance of EEG monitoring. We provide an evidence-based guide for implementing multimodal anaesthesia, encompassing drug combinations, dosages, and EEG monitoring techniques, to ensure reliable intraoperative anaesthesia while minimizing adverse effects and improving patient outcomes. RECENT FINDINGS: Opioid-free and multimodal general anaesthesia have significantly reduced opioid addiction and chronic postoperative pain. However, the evidence supporting the effectiveness of these approaches is limited. This review attempts to integrate research from broader neuroscientific fields to generate new clinical hypotheses. It discusses the correlation between high-dose intraoperative opioids and increased postoperative opioid consumption and their impact on pain indices and readmission rates. Additionally, it explores the relationship between multimodal anaesthesia and pain processing models and investigates the potential effects of nonpharmacological interventions on preoperative anxiety and postoperative pain. SUMMARY: The integration of EEG monitoring is crucial for guiding adequate multimodal anaesthesia and preventing excessive anaesthesia dosing. Furthermore, the review investigates the impact of combining regional and opioid-sparing general anaesthesia on perioperative EEG readings and anaesthetic depth. The findings have significant implications for clinical practice in optimizing multimodal anaesthesia techniques (Supplementary Digital Content 1: Video Abstract, http://links.lww.com/COAN/A96 ).

[A Case Series of Elderly Patients with Aortic Stenosis (AS) Undergoing Conscious Glaucoma Surgery in Sub-Tenon's or Subconjunctival Anaesthesia]. / Eine Fallserie wacher Glaukomoperationen mittels Sub-Tenon- oder subkonjunktivaler Anästhesie bei älteren PatientInnen mit Aortenklappenstenose.

With the current demographic changes, an increasing number of patients scheduled for glaucoma surgery presents with aortic sclerosis (AS) as part of their list of systemic diseases. This presents a definite challenge for anaesthesiologists and eye surgeons alike. We illustrate 6 cases of patients with aortic sclerosis undergoing glaucoma surgery in subconjunctival local anaesthesia or sub-Tenon block (STB). In one patient, due to discomfort, local anaesthesia had to be given repeatedly. Her blood pressure rose permanently to hypertensive values. During surgery, localised, temporal choroidal bleeding was noticed. The follow-up was complicated by exorbitant intraocular pressure swings and secondary localised choroidal bleeding. Anaesthesiologist and ophthalmic surgeon must harmonise their strategy to provide optimal transmural pressure across choroidal vessels and stenotic aortic valve outlet. Clinicians are often not aware of the core principals of each other's speciality. Our discussion considers different approaches for both disciplines to safely reduce the risk of suprachoroidal bleeding for this high-risk patient population with aortic stenosis.

Frontal electroencephalogram reveals emergence-like brain activity occurring during transition periods in cardiac surgery.

BACKGROUND: Cardiac surgery has one of the highest incidences of intraoperative awareness. The periods of initiation and discontinuation of cardiopulmonary bypass could be high-risk periods. Certain frontal EEG patterns might plausibly occur with unintended intraoperative awareness. This study sought to quantify the incidence of these pre-specified patterns during cardiac surgery. METHODS: Two-channel bihemispheric frontal EEG was recorded in 1072 patients undergoing cardiac surgery as part of a prospective observational study. Spectrograms were created, and mean theta (4-7 Hz) power and peak alpha (7-17 Hz) frequency were measured in patients under general anaesthesia with isoflurane. Emergence-like EEG activity in the spectrogram during surgery was classified as an alpha peak frequency increase by 2 Hz or more, and a theta power decrease by 5 dB or more in comparison with the median pre-bypass values. RESULTS: Data from 1002 patients were available for analysis. Fifty-five of those patients (5.5%) showed emergence-like EEG activity at least once during surgery with a median duration of 13.2 min. These patients were younger (median age, 59 vs 67 yr; P<0.001) and the median end-tidal isoflurane concentration before cardiopulmonary bypass was higher (0.82 vs 0.75 minimum alveolar concentration [MAC]; P=0.013). There was no significant difference between those with or without emergence-like EEG activity in sex, lowest core temperature, or duration of surgery. Forty-six of these EEG changes (84%) occurred within a 1 h time window centred on separation from cardiopulmonary bypass. CONCLUSION: The findings of this study suggest that approximately one in 20 patients undergoing cardiac surgery with a volatile anaesthetic agent have a sustained EEG pattern while surgery is ongoing that is often seen with emergence from general anaesthesia. Monitoring the frontal EEG during cardiopulmonary bypass may identify these events and potentially reduce the incidence of unintended awareness. CLINICAL TRIAL REGISTRATION: NCT02976584.

Lower alpha frequency of intraoperative frontal EEG is associated with postoperative delirium: A secondary propensity-matched analysis.

BACKGROUND: Postoperative delirium (POD) is a serious complication of surgery, especially in the elderly patient population. It has been proposed that decreasing the amount of anesthetics by titrating to an EEG index will lower POD rate, but clear evidence is missing. A strong age-dependent negative correlation has been reported between the peak oscillatory frequency of alpha waves and end-tidal anesthetic concentration, with older patients generating slower alpha frequencies. We hypothesized, that slower alpha oscillations are associated with a higher rate of POD. METHOD: Retrospective analysis of patients` data from a prospective observational study in cardiac surgical patients approved by the Bernese Ethics committee. Frontal EEG was recorded during Isoflurane effect-site concentrations of 0.7 to 0.8 and peak alpha frequency was measured at highest power between 6 and 17 Hz. Delirium was assessed by chart review. Demographic and clinical characteristics were compared between POD and non-POD groups. Selection bias was addressed using nearest neighbor propensity score matching (PSM) for best balance. This incorporated 18 variables, whereas patients with missing variable information or without an alpha oscillation were excluded. RESULT: Of the 1072 patients in the original study, 828 were included, 73 with POD, 755 without. PSM allowed 328 patients into the final analysis, 67 with, 261 without POD. Before PSM, 8 variables were significantly different between POD and non-POD groups, none thereafter. Mean peak alpha frequency was significantly lower in the POD in contrast to non-POD group before and after matching (7.9 vs 8.9 Hz, 7.9 vs 8.8 Hz respectively, SD 1.3, p < 0.001). CONCLUSION: Intraoperative slower frontal peak alpha frequency is independently associated with POD after cardiac surgery and may be a simple intraoperative neurophysiological marker of a vulnerable brain for POD. Further studies are needed to investigate if there is a causal link between alpha frequency and POD.

Atypical trigeminocardiac reflex during intranasal dexmedetomidine sedation of a 6-month-old premature baby.

The trigeminocardiac reflex (TCR) is an established brainstem reflex leading to parasympathetic dysrhythmias-including haemodynamic irregularities, apnoea and gastric hypermotility-during stimulation of any sensory branches of the trigeminal nerve. Most of the clinical knowledge about TCR was gathered from general anaesthesia observations, not from procedural sedation.We present a case of a 6-month-old premature baby experiencing the reflex twice under dexmedetomidine-propofol-sedation while undergoing ophthalmic and ear examination. This was interpreted as cross-over sensitisation between the facial and trigeminal cranial nerve (N V and N VII).The present case demonstrates that different TCR subtypes can occur during the same anaesthetic procedure. Triggering TCR seems to be based on several factors and not just on a single stimulus as often presumed. Therefore, for premature babies, there is a risk for TCR under procedural sedation, and we recommend using glycopyrrolate as preventive treatment.

Sub-Tenon's anaesthesia for modern eye surgery-clinicians' perspective, 30 years after re-introduction.

Sub-Tenon's block (STB) is a good technique of local anaesthesia for many types of eye surgery. It has a relatively good risk profile, in that sight- and life-threatening complications appear to be extremely rare. STB has gained popularity in the last three decades, with refinements including different types of blunt metal cannula, plastic cannulae and 'incisionless' approaches. Usage of STB varies significantly across the globe. This narrative review documents the historical evolution of STB techniques, anatomical and physiological considerations, its utility and suitability, complications, explores the current practice and possible future applications.

Actimetry-Documented Persistent Periodic Limb Movements During EEG-Confirmed Deep General Anesthesia: A Case Report.

Motor activity during general anesthesia (GA) without neuromuscular blockade is often interpreted as reflecting insufficient anesthesia. Here we present the case of an octogenarian undergoing deep sclerectomy with opioid-sparing electroencephalography (EEG)-guided anesthesia. Periodic leg movements (PLM) appeared during ongoing surgery while the patient's raw EEG displayed a pattern of deep anesthesia, evidenced by burst suppression. Recognizing PLM in the context of opioid-sparing GA is of importance for anesthesiologists, as deep anesthesia is not necessarily associated with a decrease in motor activity.

Association of Intravitreal Injections With Blood Pressure Increase: The Following Excitement and Anxiety Response Under Intravitreal Injection Study.

Importance: Despite the unquestionable effectiveness of anti-vascular endothelial growth factor therapy (VEGF), there is ongoing controversy about potential systemic adverse effects. Besides the direct adverse effects of anti-VEGF agents, other factors associated with the injection itself, such as perioperative blood pressure fluctuations, may contribute to adverse events. Objective: To determine blood pressure fluctuations during intravitreal injections. Design, Setting, and Participants: Prospective observational study at a tertiary referral center (Department of Ophthalmology, University Hospital Bern, Bern, Switzerland). Consecutive patients scheduled for intravitreal injections were recruited. Data were analyzed between October 2017 and January 2018. Main Outcomes and Measures: Systolic and diastolic blood pressure, pulse rate, and oxygen saturation were recorded before, during, and after the intravitreal injection. An anxiety questionnaire was completed by all participants. Multivariate regression analysis was used to investigate potential factors associated with blood pressure rise during injections. Results: Two hundred one patients (92 women and 109 men) were included in this study, with a mean age of 68 years (range, 18-93 years). Mean (SD) systolic blood pressure increased from a baseline of 150 (20) mm Hg to 162 (24) mm Hg following the preparation procedure to 168 (24) mm Hg during the injection (P < .001). Mean (SD) diastolic blood pressure increased from 78 (14) mm Hg to 83 (37) mm Hg to 83 (16) mm Hg, respectively (P = .009). Mean (SD) pulse frequency increased from 76 (13) bpm to 80 (13) bpm (P = .005). In total, 23 patients (11%) had a systolic blood pressure greater than 200 mm Hg. This subgroup of patients had a mean (SD) perioperative systolic blood pressure increase from 182 (19) mm Hg to 214 (12) mm Hg, resulting in an increase of 32 (20) mm Hg (P < .001). Age and anxiety were to be next associated with systolic blood pressure rise. Conclusions and Relevance: The intravitreal injection process is associated with a transient increase in blood pressure. Most of the increase occurs following the preparation before the injection itself. This may constitute a risk factor for cardiovascular or cerebrovascular complications during treatment and could be of particular relevance in patients at high risk for such events and those receiving frequent injections. Future work may be needed to determine whether, in patients at risk for cardiovascular or cerebrovascular events, perioperative blood pressure monitoring or antihypertensive therapy needs to be considered.

Early prognostic value of the medical emergency team calling criteria in patients admitted to intensive care from the emergency department.

OBJECTIVES: To evaluate the early prognostic value of the medical emergency team (MET) calling criteria in patients admitted to intensive care from the emergency department. DESIGN: Retrospective cohort study. SETTING: Emergency department and department of intensive care medicine of a 960-bed tertiary referral hospital. PATIENTS: A total of 452 consecutive adult patients admitted to intensive care from the emergency department from January 1, 2004, to December 31, 2004. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: MET calling criteria were retrospectively extracted from patient records, and the sum of positive criteria was calculated for the first hour in the emergency department (METinitial) and subsequently until admission to the intensive care unit in a series of time periods. The maximum number of positive MET calling criteria during any time period was defined (METmax). Logistic regression analysis revealed METinitial (odds ratio [OR] 3.392, 95% confidence interval [CI] 2.534-4.540) and METmax (OR 3.867, 95% CI 2.816-5.312) to be significant predictors of hospital mortality, the need for mechanical ventilation (METinitial: OR 4.151, 95% CI 3.53-4.652; METmax: OR 4.292, 95% CI 3.151-5.846), and occurrence of hemodynamic instability (METinitial: OR 1.548, 95% CI 1.258-1.905; METmax: OR 1.685, 95% CI 1.355-2.094) (all p < .0001). CONCLUSIONS: MET scores collected early after admission or throughout the stay in the emergency department allow for simple identification of patients at risk of unfavorable outcome during the subsequent intensive care unit stay.