Reflections on training and teaching modes for anesthesia monitoring nurses in China.

Objective: The purpose of this scoping review was to map and identify studies describing the current state of research and teaching methods and evaluation systems for nurse anesthetists within China. Design: A wide-ranging search of multiple databases and gray literature was performed according to JBI criteria, employing predefined selection criteria and following PRISMA guidelines. Methods: This scoping review included studies published between 1988 and 2021 that explored the current state of clinical training and teaching methods for nurse anesthetists nationally and internationally. These articles were reviewed by four reviewers and content analysis was performed. Results: Fifty-two articles were included in the review. The results suggest that both simulation teaching in nursing education and Kolb's experiential learning cycle theory improve nursing staff teamwork, develop critical thinking skills, and improve core nursing competencies. Conclusions: High-fidelity simulation teaching based on Kolb's experiential learning cycle theory may be an effective teaching method to develop and improve the competence of nurse anesthesia monitors.

Performance of the bispectral index and electroencephalograph derived parameters of anesthetic depth during emergence from xenon and sevoflurane anesthesia.

Many processed EEG monitors (pEEG) are unreliable when non-GABAergic anesthetic agents are used. The primary aim of the study was to compare the response of the Bispectral Index (BIS) during emergence from anesthesia maintained by xenon and sevoflurane. To better understand the variation in response of pEEG to these agents, we also compared several EEG derived parameters relevant to pEEG monitoring during emergence. Twenty-four participants scheduled for lithotripsy were randomized to receive xenon or sevoflurane anesthesia. Participants were monitored with the BIS and had simultaneous raw EEG collected. BIS index values were compared at three key emergence timepoints: first response, eyes open and removal of airway. Two sets of EEG derived parameters, three related to the BIS: relative beta ratio, SynchFastSlow and SynchFastSlow biocoherence, and two unrelated to the BIS: spectral edge frequency and the composite cortical state, were calculated for comparison. BIS index values were significantly lower in the xenon group than the sevoflurane group at each emergence timepoint. The relative beta ratio parameter increased significantly during emergence in the sevoflurane group but not in the xenon group. The spectral edge frequency and composite cortical state parameters increased significantly in both groups during emergence. The BIS index is lower at equivalent stages of behavioural response during emergence from xenon anesthesia when compared to sevoflurane anesthesia, most likely due to differences in how these two agents influence the relative beta ratio. The spectral edge frequency and composite cortical state might better reflect emergence from xenon anaesthesia.Clinical trial number and registry Australia New Zealand Clinical Trials Registry Number: ACTRN12618000916246.

Revolutionizing Patient Care: A Comprehensive Review of Artificial Intelligence Applications in Anesthesia.

This review explores the intersection of artificial intelligence (AI) and anesthesia, examining its transformative impact on patient care across various phases. Beginning with a historical overview of anesthesia, we highlight the critical role of technological advancements in ensuring optimal patient outcomes. The emergence of AI in healthcare sets the stage for a comprehensive analysis of its applications in anesthesia. In the preoperative phase, AI facilitates personalized risk assessments and decision support, optimizing anesthesia planning and drug dosage predictions. Moving to the intraoperative phase, we delve into AI's role in monitoring and control through sophisticated anesthesia monitoring and closed-loop systems. Additionally, we discuss the integration of robotics and AI-guided procedures, revolutionizing surgical assistance. Transitioning to the postoperative phase, we explore AI-driven postoperative monitoring, predictive analysis for complications, and the integration of AI into rehabilitation programs and long-term follow-up. These new applications redefine patient recovery, emphasizing personalized care and proactive interventions. However, the integration of AI in anesthesia poses challenges and ethical considerations. Data security, interpretability, and bias in AI algorithms demand scrutiny. Moreover, the evolving patient-doctor relationship in an AI-driven care landscape requires a delicate balance between efficiency and human touch. Looking forward, we discuss the future directions of AI in anesthesia, anticipating advances in technology and AI algorithms. The integration of AI into routine clinical practice and its potential impact on anesthesia education and training are explored, emphasizing the need for collaboration, education, and ethical guidelines. This review provides a comprehensive overview of AI applications in anesthesia, offering insights into the present landscape, challenges, and future directions. The synthesis of historical perspectives, current applications, and future possibilities underscores the transformative potential of AI in revolutionizing patient care within the dynamic field of anesthesia.

Sevoflurane requirements during electroencephalogram (EEG)-guided vs standard anesthesia Care in Children: A randomized controlled trial.

STUDY OBJECTIVES: Intra-operative electroencephalographic (EEG) monitoring utilizing the spectrogram allows visualization of children's brain response during anesthesia and may complement routine cardiorespiratory monitoring to facilitate titration of anesthetic doses. We aimed to determine if EEG-guided anesthesia will result in lower sevoflurane requirements, lower incidence of burst suppression and improved emergence characteristics in children undergoing routine general anesthesia, compared to standard care. DESIGN: Randomized controlled trial. SETTING: Tertiary pediatric hospital. PATIENTS: 200 children aged 1 to 6 years, ASA 1 or 2, undergoing routine sevoflurane anesthesia for minor surgery lasting 30 to 240 min. INTERVENTIONS: Children were randomized to either EEG-guided anesthesia (EEG-G) or standard care (SC). EEG-G group had sevoflurane titrated to maintain continuous slow/delta oscillations on the raw EEG and spectrogram, aiming to avoid burst suppression and, as far as possible, maintain a patient state index (PSI) between 25 and50. SC group received standard anesthesia care and the anesthesia teams were blinded to EEG waveforms. MEASUREMENTS: The primary outcomes were the average end-tidal sevoflurane concentration during induction and maintenance of anesthesia. Secondary outcomes include incidence and duration of intra-operative burst suppression and Pediatric Anesthesia Emergence Delirium (PAED) scores. RESULTS: The EEG-G group received lower end-tidal sevoflurane concentrations during induction [4.80% vs 5.67%, -0.88% (-1.45, -0.31) p = 0.003] and maintenance of anesthesia [2.23% vs 2.38%, -0.15% (-0.25, -0.05) p = 0.005], and had a lower incidence of burst suppression [3.1% vs 10.9%, p = 0.044] compared to the SC group. PAED scores were similar between groups. Children <2 years old required higher average end-tidal sevoflurane concentrations, regardless of group. CONCLUSIONS: EEG-guided anesthesia care reduces sevoflurane requirements in children undergoing general anesthesia, possibly lowering the incidence of burst suppression, without altering emergence characteristics. EEG monitoring allows direct visualization of brain responses in real time and allows clearer appreciation of varying sevoflurane requirements in children of different ages.

General Anesthetic Management of a Patient With Kleine-Levin Syndrome.

Kleine-Levin syndrome (KLS) is a rare sleep disorder characterized by periodic hypersomnia and behavioral or cognitive disturbances. Although prolonged emergence from general anesthesia and postoperative hypersomnia may occur in a patient with KLS, there is little information about the safe anesthetic management of these patients. We describe the case of a 22-year-old female previously diagnosed with KLS who was scheduled to have her third molars extracted under general anesthesia. Because the patient had symptoms of periodic hypersomnia and hyperphagia, the surgery was scheduled during a KLS crisis interval. General anesthesia was induced with propofol, remifentanil, and rocuronium, and maintained with desflurane and remifentanil. To prevent overuse of anesthetic agents, an electroencephalogram (EEG)-based depth of anesthesia monitor (SedLine; Masimo Corporation) was used intraoperatively. A neuromuscular monitor was also used to carefully titrate use of a neuromuscular blocking agent. After surgery, sugammadex was administered, and the patient quickly emerged within 10 minutes, as also confirmed by the EEG monitor. She had no KLS recurrence postoperatively. When anesthetizing patients with KLS, an EEG-based depth of anesthesia monitor and neuromuscular monitor may be warranted to ensure complete emergence from general anesthesia. In addition, elective surgery should be planned during crises intervals.

Research progress of anesthesia-related neural network in depth of anesthesia monitoring / 中国临床药理学与治疗学

Improper control of depth of anesthesia is not only detrimental to the rapid and stable recovery of anesthesia, but also affects the postoperative outcome of patients. Therefore, accurate control of anesthesia depth is an urgent clinical and scientific problem in the field of anesthesiology. At present, different algorithm models derived from electroencephalogram (EEG) signals are used to monitor the depth of anesthesia, but they cannot meet the requirements of anesthesiologists to accurately evaluate the depth of anesthesia. In recent years, the research on the mechanism and modulation of anesthesia-related neural network suggests that it has potential value as a method to monitor depth of anesthesia. Anesthesia-related neural networks mainly include sleep-wake circuit, thalamic-cortical circuit and corticocortical network. A thorough understanding of the neural network involved in the loss of consciousness caused by anesthesia will guide the depth of anesthesia monitoring more accurately and provide possibility for improving the quality of clinical anesthesia resuscitation.

Electroencephalography-demonstrated mechanisms of dexmedetomidine-mediated deepening of propofol anesthesia: an observational study.

BACKGROUND: Although dexmedetomidine (Dex) is known to reduce bispectral index (BIS) values and propofol dosage, there is little information regarding raw electroencephalography (EEG) changes related to Dex deepening of propofol general anesthesia (GA). This study investigated the Dex effects on propofol GA via analysis of EEG changes. METHODS: A study cohort of 21 surgical patients (age range, 20-60 years) categorized as American Society of Anesthesiologists (ASA) class I or II was enrolled. We used time-varying spectral and bicoherence methods to compare electroencephalogram signatures 5 min before versus 10 min after intravenous Dex injection under propofol GA. The means and medians are reported with 95% confidence intervals (CIs) and inter-quartile ranges (IQRs), respectively. RESULTS: Dex augmented the slow waves power and theta (θ) oscillation bicoherence peak from a mean (95% CI) of 22.1% (19.0, 25.2) to 25.2% (21.8, 28.6). Meanwhile, Dex reduced alpha (α) peak power and bicoherence from 3.5 dB (1.0, 6.0) and 41.5% (34.0, 49.0) to 1.7 dB (- 0.6, 4.0) and 35.4% (29.0, 41.8), respectively, while diminishing the median frequency of α oscillation peak values and the mean frequency of α peaks in bicoherence spectra from 12.0 Hz (IQR 11.2, 12.6) and 11.7 Hz (11.3, 12.2) to 11.1 Hz (IQR 10.3, 11.8) and 11.2 Hz (10.9, 11.6), respectively. CONCLUSIONS: Profound EEG changes support the supposition that Dex enhances propofol-induced GA from a moderate to a deeper state. The present findings provide a theoretical basis and reference regarding protocols aimed at reducing anesthetic/sedative dosage while maintaining sufficient depth of GA. CLINICAL TRIAL REGISTRATION: ChiCTR, ChiCTR1900026955 . Registered on 27 October 2019.

Validation of a new approach for distinguishing anesthetized from awake state in patients using directed transfer function applied to raw EEG.

We test whether a measure based on the directed transfer function (DTF) calculated from short segments of electroencephalography (EEG) time-series can be used to monitor the state of the patients also during sevoflurane anesthesia as it can for patients undergoing propofol anesthesia. We collected and analyzed 25-channel EEG from 7 patients (3 females, ages 41-56 years) undergoing surgical anesthesia with sevoflurane, and quantified the sensor space directed connectivity for every 1-s epoch using DTF. The resulting connectivity parameters were compared to corresponding parameters from our previous study (n = 8, patients anesthetized with propofol and remifentanil, but otherwise using a similar protocol). Statistical comparisons between and within studies were done using permutation statistics, a data driven algorithm based on the DTF-parameters was employed to classify the epochs as coming from awake or anesthetized state. According to results of the permutation tests, DTF-parameter topographies were significantly different between the awake and anesthesia state at the group level. However, the topographies were not significantly different when comparing results computed from sevoflurane and propofol data, neither in the awake nor in anesthetized state. Optimizing the algorithm for simultaneously having high sensitivity and specificity in classification yielded an accuracy of 95.1% (SE = 0.96%), with sensitivity of 98.4% (SE = 0.80%) and specificity of 94.8% (SE = 0.10%). These findings indicate that the DTF changes in a similar manner when humans undergo general anesthesia caused by two distinct anesthetic agents with different molecular mechanisms of action.

Performance of blink reflex in patients during anesthesia induction with propofol and remifentanil: prediction probabilities and multinomial logistic analysis.

BACKGROUND: The amount of propofol needed to induce loss of responsiveness varied widely among patients, and they usually required less than the initial dose recommended by the drug package inserts. Identifying precisely the moment of loss of responsiveness will determine the amount of propofol each patient needs. Currently, methods to decide the exact moment of loss of responsiveness are based on subjective analysis, and the monitors that use objective methods fail in precision. Based on previous studies, we believe that the blink reflex can be useful to characterize, more objectively, the transition from responsiveness to unresponsiveness. The purpose of this study is to investigate the relation between the electrically evoked blink reflex and the level of sedation/anesthesia measured with an adapted version of the Richmond Agitation-Sedation Scale, during the induction phase of general anesthesia with propofol and remifentanil. Adding the blink reflex to other variables may allow a more objective assessment of the exact moment of loss of responsiveness and a more personalized approach to anesthesia induction. RESULTS: The electromyographic-derived features proved to be good predictors to estimate the different levels of sedation/anesthesia. The results of the multinomial analysis showed a reasonable performance of the model, explaining almost 70% of the adapted Richmond Agitation-Sedation Scale variance. The overall predictive accuracy for the model was 73.6%, suggesting that it is useful to predict loss of responsiveness. CONCLUSIONS: Our developed model was based on the information of the electromyographic-derived features from the blink reflex responses. It was able to predict the drug effect in patients undergoing general anesthesia, which can be helpful for the anesthesiologists to reduce the overwhelming variability observed between patients and avoid many cases of overdosing and associated risks. Despite this, future research is needed to account for variabilities in the clinical response of the patients and with the interactions between propofol and remifentanil. Nevertheless, a method that could allow for an automatic prediction/detection of loss of responsiveness is a step forward for personalized medicine.

An integrated microcatheter-based dual-analyte sensor system for simultaneous, real-time measurement of propofol and fentanyl.

According to the American Society of Anesthesiologists Closed Claims Database, one of three drug-related errors is the result administrating an incorrect dose. Directly measuring drug concentration removes the uncertainty in the dose-concentration relationship and addresses inter- and intra-subject variabilities that affect the pharmacokinetics of anesthetics. Here we describe a dual-analyte microcatheter-based electrochemical sensor capable of simultaneous real-time continuous monitoring of fentanyl (FTN) and propofol (PPF) drugs simultaneously in the operating rooms. Such a dual PPF/FTN catheter sensor relies on embedding two different modified carbon paste (CP)-packed working electrodes along with Ag/AgCl microwire reference electrodes within a mm-wide Teflon tube, and uses a square wave voltammetric (SWV) technique. The composition of each working electrode was judiciously tailored to cover the concentration range of interest for each analyte. A polyvinyl chloride (PVC) organic polymer coating on the surface of CP electrode enabled selective and sensitive PPF measurements in µM range. The detection of nM FTN levels was achieved through a multilayered nanostructure-based surface modification protocol, including a CNT-incorporated CP transducer modified by a hybrid of electrodeposited Au nanoparticles and electrochemically reduced graphene oxide (erGO) and a PVC outer membrane. The long-term monitoring capability of the dual sensor was demonstrated in a protein-rich artificial plasma medium. The promising antibiofouling behavior of the catheter-based multiplexed sensor was also illustrated in whole blood samples. The new integrated dual-sensor microcatheter platform holds considerable promise towards real-time, in-vivo detection of the anesthetic drugs, propofol and fentanyl, during surgical procedures towards significantly improved safe delivery of anesthetic drugs.

Intraoperative Optimization of Both Depth of Anesthesia and Cerebral Oxygenation in Elderly Patients Undergoing Coronary Artery Bypass Graft Surgery-A Randomized Controlled Pilot Trial.

OBJECTIVES: Does intraoperative optimization of both depth of anesthesia and regional cerebral tissue oxygenation (rScO2) in elderly patients reduce postoperative cognitive decline (primary outcome) or delirium (secondary outcome)? DESIGN: Prospective randomized controlled single blind trial. SETTING: A single major urban teaching and university hospital and tertiary referral center. PARTICIPANTS: Patients, 65 years of age and older, undergoing elective coronary artery bypass graft surgery on cardiopulmonary bypass. INTERVENTIONS: Intraoperative depth of anesthesia bispectral index (BIS) values were targeted at 50 ± 10. Regional cerebral tissue desaturations of more than 15% of the pre-induction value, or below 50%, were avoided. MEASUREMENTS AND MAIN RESULTS: Eighty-two patients were included, and mean depth of anesthesia values using BIS were significantly higher during surgery in the intervention group with 40.6 (7.3) versus 35.4 (6.7) in the control group, mean (standard deviation), p = 0.004. The cognitive function was similar between the treatment and control groups at 6 weeks postoperatively with a Mini Mental State Examination (MMSE) of 27 (26,29) in the intervention group and an MMSE of 29 (27,29) in the control group, median (interquartile range), with p = 0.12. The authors observed a reduction in the incidence of delirium, occurring in 2.4% (n = 1) of patients in the intervention group and in 20% (n = 8) in the control group (p = 0.01). CONCLUSIONS: This pilot trial demonstrates that noninvasive target-controlled depth of anesthesia monitoring is feasible. Cognitive function at 6 weeks showed no difference between the treatment and control groups; however, postoperative delirium was reduced in the intervention group.

Advances in Anesthesia Monitoring.

During surgery, one of the primary functions of the anesthesiologist is to monitor the patient and ensure safe and effective conduct of anesthesia to provide the optimum operating conditions. Standard guidelines for perioperative monitoring have been firmly established by the American Society of Anesthesiologists. However, in recent years, new advances in technology has led to the development of many new monitoring modalities, especially involving the neurologic and cardiovascular systems. This article presents a targeted review to discuss the functions and limitations of these new monitors and how they are applied in the modern operating room setting.

In Vivo Imaging of Microvasculature during Anesthesia with High-Resolution Photoacoustic Microscopy.

Anesthesia monitoring is extremely important in improving the quality of anesthesia and ensuring the safety of patients in operation. Photoacoustic microscopy (PAM) is proposed to in vivo image the skin microvasculature of 10 nude mice undergoing general anesthesia by using the isoflurane gas with a concentration of 3%. Benefiting from strong optical absorption of hemoglobin, PAM has good contrast and high resolution in mapping of microvasculature. A series of high quality images can clearly reveal the subtle changes of capillaries in morphology over time. Two indices, vessel intensity and vessel density, are extracted from these images to measure the microvasculature quantitatively. The imaging results show that the vessel intensity and density are increased over time. After 65 min, the vessel intensity increased 42.7 ± 8.6% and the density increased 28.6 ± 12.2%. These indices extracted from photoacoustic images accurately reflect the greater blood perfusion undergoing general anesthesia. Additionally, abnormal reductions of vessel intensity and density are also observed as overtime anesthesia. This preclinical study suggests that PAM holds potential to monitor anesthesia by imaging the skin microvasculature.

Investigation of data-driven optical neuromonitoring approach during general anesthesia with sevoflurane.

Anesthesia monitoring currently needs a reliable method to evaluate the effects of the anesthetics on its primary target, the brain. This study focuses on investigating the clinical usability of a functional near-infrared spectroscopy (fNIRS)-derived machine learning classifier to perform automated and real-time classification of maintenance and emergence states during sevoflurane anesthesia. For 19 surgical procedures, we examine the entire continuum of the maintenance-transition-emergence phases and evaluate the predictive capability of a support vector machine (SVM) classifier during these phases. We demonstrate the robustness of the predictions made by the SVM classifier and compare its performance with that of minimum alveolar concentration (MAC) and bispectral (BIS) index-based predictions. The fNIRS-SVM investigated in this study provides evidence to the usability of the fNIRS signal for anesthesia monitoring. The method presented enables classification of the signal as maintenance or emergence automatically as well as in real-time with high accuracy, sensitivity, and specificity. The features local mean HbTotal, std [Formula: see text], local min Hb and [Formula: see text], and range Hb and [Formula: see text] were found to be robust biomarkers of this binary classification task. Furthermore, fNIRS-SVM was capable of identifying emergence before movement in a larger number of patients than BIS and MAC.

Simultaneous on-line monitoring of propofol and sevoflurane in balanced anesthesia by direct resistive heating gas chromatography.

In balanced anesthesia, sevoflurane and propofol are often used in combination to achieve a better anesthetic effect. However, methods for on-line monitoring of concentrations of the two anesthetics in patients are still rare in clinical. This study proposed a non-invasive method utilizing a fast gas chromatograph combined with a surface acoustic wave sensor (Fast GC-SAW) to simultaneously on-line monitor sevoflurane and propofol in patients' exhaled gas. By using the direct resistive heating capillary column, the single detection time of Fast GC-SAW system was significantly shortened to 90s, as well as the size reduced to (40cm×30cm×20cm). Besides, in the calibration of sevoflurane, Fast GC-SAW system showed a good linear correlation (R2=0.9925, P<0.01) with gas chromatography-mass spectrometer (GC-MS), which ensured the reliability and accuracy of the Fast GC-SAW system. Finally, clinical experiments on patients under balanced anesthesia were conducted. The varied concentrations measured by Fast GC-SAW extraordinarily matched the clinical usages of these two anesthetics.

Monitoring for the Oral and Maxillofacial Surgeon.

Parenteral medications are titrated in the oral and maxillofacial surgery office to achieve moderate sedation, deep sedation, or general anesthesia while continuously maintaining spontaneous ventilation with an open airway. After initial drug administration, the provider assesses and interprets both the level of anesthesia and the presence/severity of adverse side effects, both of which guide further drug titration, cessation, reversal, or medical management. This assessment is called monitoring, which guides the conduct of anesthesia delivery and becomes the essence of this art.

Effects of multiple monitoring of total intravenous anesthesia on postoperative cognitive dysfunction in ;elderly patients / 临床麻醉学杂志

Objective To observe the effect of multiple monitoring of total intravenous anes-thesia on postoperative cognitive function in elderly patients.Methods Elective 100 patients undergo-ing general anesthesia for abdominal operation,56 males,44 females,aged 65-80 years,ASA physi-cal status Ⅱ or Ⅲ.All patients were divided into multiple monitoring group (group M)and routine monitoring group (group R)by random digital table method,n =50 each.In group M,the anesthesi-ologists modulated anesthetic drugs to make NTI of 37-56 and rSO 2 higher than 50% or not lower than the baseline value by 20%,while in group R the infusion rate of propofol,remifentanil and cisa-tracurium was adjusted by anesthesiologists according to anesthesiologist’s experiences by the pa-tients’monitoring index.Cognitive function of patients in the two groups were evaluated using MMSE 1 d before surgery and 1 d,3 d,7 d,1 month and 3 months after surgery.The occurrence of cognitive dysfunction 7 d,1 month and 3 months after surgery,the postoperative recovery and the dosage of propofol,remifentanil and cisatracurium were recorded.Blood was randomly selected from each group to determine the serum content of S100βand Aβ1-42 by ELISA method at the time point of before surgery (T0 ),one hour after starting surgery (T1 ),the end of surgery (T2 )and postopera-tive 24 hours (T3 ).Results The incidence of postoperative cognitive decline in group M on 1 d (8%vs.22%),3 d (2% vs.1 6%)after surgery were significantly lower than that in group R (P <0.05). Postoperative cognitive dysfunction between the two groups 7 d and 1 month,3 months after surgery has no statistical significance.The dose of propofol [(3.3 ± 0.8)mg · kg-1 · h-1 vs.(3.7 ± 0.7 ) mg·kg-1 ·h-1 ,P < 0.05 ] and cisatracurium [(104 ± 47 )μg · kg-1 · h-1 vs.(124 ± 68 )μg·kg-1 ·h-1 ,P <0.05]in group M was less than that in group R.The time of eye-opening [(10 ±3)min vs.(1 6±6)min,P <0.01],extubation [(13±3)min vs.(22±7)min,P <0.01]and lo-cation [(1 7±4)min vs.(27 ±9)min,P <0.01 ]was shorter in group M.Compared with T0 ,the serum level of S100βprotein was significantly increased in group M at T1 ,T2 and group R at T1-T3 (P <0.05);The level of serum S100βprotein in group M was significantly lower than that in group R (P <0.05).Compared with T0 ,Aβ1-42 protein level was significantly reduced in two groups at T1 and T2 (P <0.05),but there was no significant difference between the two groups.Conclusion Total intravenous anesthesia with multiple monitoring can reduce neural injury and reduce the incidence of early postoperative cognitive decline in elderly patients with abdominal surgery,but has no significant effect on the incidence of POCD.

[Undesired awareness phenomena during general anesthesia: Evidence-based state of knowledge, current discussions and strategies for prevention and management]. / Unerwünschte Wachphänomene ("Awareness") während Allgemeinanästhesie: Evidenzbasierter Kenntnisstand, aktuelle Diskussionen und Strategien zu Prävention und Management.

Patient awareness during general anesthesia and the later recall of what happened during surgery can be experienced by patients as horrifying events that leave lasting mental trauma in the form of posttraumatic stress syndrome (PTSS). Awareness is related to a temporary insufficient depth of anesthesia. This phenomenon has been discussed for more than 20 years. According to randomized controlled studies, in the absence of risk factors awareness phenomena occur in 1-2 per 1000 operations involving general anesthesia (0.1-0.2%) and are classified as occasionally occurring critical events. An astonishing twist occurred elicited by the recent data from the 5th National Audit Project from Great Britain (NAP5) published in the British Journal of Anaesthesia and in Anaesthesia. The NAP5 evaluated patient reports of accidental awareness during general anesthesia (AAGA) in a multicenter manner in more than 2.7 million cases and indicated incidences of awareness of only 1:19,600, a frequency 20 times less than previously reported. These results gave rise to some controversy. It seems likely that, due to the absence of structured interviews, the NAP5 data only demonstrated the tip of the iceberg and may have vastly underestimated the real incidence of intraoperative awareness. The present overview summarizes the current knowledge about awareness. Furthermore, it addresses the question whether the awareness problem has been overestimated by evidence-based criteria or underestimated by the results of the NAP5. The responsibility for sufficient anesthesia in the clinical routine requires knowledge of awareness risks and potential sequelae. A formal recommendation from the German Society of Anesthesia and Intensive Care Medicine (DGAI) concerning awareness is not yet available; however, the recognition of evidence-based strategies in the management of anesthesia may minimize the occurrence of awareness and its sequelae.