Detection method of intraoperative awareness: a randomized comparative study.

BACKGROUND: : The incidence of intraoperative awareness varies in a wide range in the literature. The reasons for these different results include the questioning method used and the questioning time. The goal of this study is to compare the effectiveness of different questioning methods and times used in intraoperative awareness research for detecting the incidence. METHODS: We recruited patients between the ages of 18-70 years, with normal cognitive functions and able to speak after general anesthesia to the study. The patients were randomly divided into two groups. In Group 1 we applied the modified Brice questionnaire in the first 2 h and 24 h after surgery for investigating intraoperative awareness. In Group 2, 24 h after surgery, we asked about anesthesia satisfaction and patients' complaints, if any. RESULTS: There was no statistically significant difference between the groups in terms of age (p = 0.514).The proportion of women was significantly higher (p = 0.002), the duration of anesthesia was shorter, and the rate of narcotic analgesic use was higher in Group 2 (p < 0.001). The assessment in the first 2 h showed the frequency of awareness was statistically higher in Group 1 than in Group 2 (p = 0.016). In the postoperative 24-h assessment, we found no significant difference in the incidence of intraoperative awareness between the groups (p < 0.05). In Group 1, there was no statistically significant difference in terms of incidence of awareness according to evaluation time (p = 250). DISCUSSION: The incidence of intraoperative awareness in Group 1 was significantly higher than in Group 2 in the evaluation conducted in the first 2 h. There was no significant difference in the determination of intraoperative awareness between questioning times in group 1.

Incidence of accidental awareness during general anaesthesia in obstetrics: a multicentre, prospective cohort study.

General anaesthesia for obstetric surgery has distinct characteristics that may contribute towards a higher risk of accidental awareness during general anaesthesia. The primary aim of this study was to investigate the incidence, experience and psychological implications of unintended conscious awareness during general anaesthesia in obstetric patients. From May 2017 to August 2018, 3115 consenting patients receiving general anaesthesia for obstetric surgery in 72 hospitals in England were recruited to the study. Patients received three repetitions of standardised questioning over 30 days, with responses indicating memories during general anaesthesia that were verified using interviews and record interrogation. A total of 12 patients had certain/probable or possible awareness, an incidence of 1 in 256 (95%CI 149-500) for all obstetric surgery. The incidence was 1 in 212 (95%CI 122-417) for caesarean section surgery. Distressing experiences were reported by seven (58.3%) patients, paralysis by five (41.7%) and paralysis with pain by two (16.7%). Accidental awareness occurred during induction and emergence in nine (75%) of the patients who reported awareness. Factors associated with accidental awareness during general anaesthesia were: high BMI (25-30 kg.m-2 ); low BMI (<18.5 kg.m-2 ); out-of-hours surgery; and use of ketamine or thiopental for induction. Standardised psychological impact scores at 30 days were significantly higher in awareness patients (median (IQR [range]) 15 (2.7-52.0 [2-56]) than in patients without awareness 3 (1-9 [0-64]), p = 0.010. Four patients had a provisional diagnosis of post-traumatic stress disorder. We conclude that direct postoperative questioning reveals high rates of accidental awareness during general anaesthesia for obstetric surgery, which has implications for anaesthetic practice, consent and follow-up.

Unintended intraoperative awareness: An analysis of Perioperative Anesthetic Adverse Events in Thailand (PAAd Thai).

BACKGROUND: Despite the improvement of anesthetic-related modalities, the incidence of unintended intraoperative awareness remains at around 0.005-0.038%. OBJECTIVE: We aimed to describe the intraoperative awareness incidents that occurred across Thailand between January to December, 2015. METHODS: Observational data was collected from 22 hospitals throughout Thailand. The awareness category was selected from incident reports according to the Perioperative Anesthetic Adverse Events in Thailand (PAAd Thai) study database and descriptive statistics were analyzed. The awareness characteristics and the related factors were recorded. RESULTS: A total of nine intraoperative awareness episodes from 2000 incidents were observed. The intraoperative awareness results were as follows: experience of pain (38.1%), perception of sound (33.3%), perception of intubation (9.5%) and feeling of paralysis (14.3%). The observed factors that affect intraoperative awareness were anesthesia-related (100%), patient-related (55.5%), surgery-related (22.2%) and systematic process-related (22.2%). The contributing factors were situational inexperience (77.8%) and inappropriate patient evaluation (44.4%). An awareness of anesthetic performer (100%) and experience (88.9%) were defined as incident-mitigating factors. The suggested corrective strategies were quality assurance activity (88.9%), improved supervision (44.4%) and equipment utilization (33.3%), respectively. CONCLUSION: Nine intraoperative awareness incidents were observed, however the causes were preventable. The anesthetic component seems to be the most influential to prevent these events.

The relation between preoperative anxiety and awareness during anesthesia: an observational study / Relação entre ansiedade pré-operatória e consciência durante a anestesia: estudo observacional

Abstract Background: Anxiety is a state of worry caused by the anticipation of external or internal danger. Awareness During Anesthesia (ADA) is an unexpected memory recall during anesthesia. In this study, we aimed to determine the factors that affect preoperative anxiety and observe the incidence of ADA, as well as to determine the anxiety levels of these patients with a history of ADA. Methods: This study was planned to be prospective, observational, and cross-sectional. Patients in whom septoplasty was planned, who was admitted to the anesthesiology outpatients between March 2018 and September 2018, were ASA I-II, and aged 18-70 years were included in the study. The demographic characteristics of patients were recorded. The State-Trait Anxiety Inventory (STAI) was used to determine anxiety during a preoperative evaluation. The modified Brice awareness score was used simultaneously to determine previous ADA. Results: The anxiety scores of patients who were conscious during anesthesia were higher than other patients. The mean STAI score was 40.85 ± 14.8 in the 799 patients who met the inclusion criteria of this study. When the anxiety scores were compared, the scores were higher in females than in males (p < 0.05). The mean STAI score was found as 40.3 ± 13.8 in patients who dreamed during anesthesia. Conclusion: It is important to determine the anxiety levels of patients in the preoperative period to prevent the associated complications. Preoperative anxiety, besides preventing ADA, should be dealt with in a multidisciplinary manner. ADA should be carefully questioned while evaluating previous anesthesia experiences.

Resumo Justificativa: A ansiedade é um estado de preocupação causado pela expectativa de perigo externo ou interno. Consciência durante a anestesia (CDA) é a evocação imprevista da memória de eventos intranestésicos. O objetivo deste estudo foi determinar os fatores que afetam a ansiedade pré-operatória, a incidência de CDA e os níveis de ansiedade nos pacientes com antecedente de CDA. Método: O estudo foi planificado como prospectivo, observacional e transversal. Foram incluídos no estudo pacientes programados para septoplastia eletiva, admitidos ao ambulatório de anestesiologia entre Março de 2018 e Setembro de 2018, com classe funcional ASA I-II e faixa etária entre 18 e 70 anos. As características demográficas dos pacientes foram registradas. O Inventário de Ansiedade Traço-Estado (IDATE) foi utilizado para determinar a ansiedade durante a avaliação pré-operatória. Simultaneamente, o escore de consciência de Brice modificado foi usado para determinar CDA anterior. Resultados: Os escores de ansiedade dos pacientes que apresentaram CDA foram mais elevados do que de outros pacientes. A pontuação média do IDATE foi 40,85±14,8 nos 799 pacientes que obedeceram aos critérios de inclusão do estudo. Quando os escores de ansiedade foram comparados, foram maiores no sexo feminino do que no masculino (p < 0,05). O escore médio do IDATE encontrado foi 40,3±13,8 nos pacientes que relataram sonhos durante a anestesia. Conclusão: É importante determinar no pré-operatório os níveis de ansiedade dos pacientes para evitar as complicações associadas. Ansiedade pré-operatória e a prevenção de CDA devem ser tratadas com abordagem multiprofissional. A CDA deve ser cuidadosamente investigada, avaliando-se as experiências vividas pelo paciente em anestesias pregressas.

Protocol for direct reporting of awareness in maternity patients (DREAMY): a prospective, multicentre cohort study of accidental awareness during general anaesthesia.

BACKGROUND: Accidental awareness during general anaesthesia (AAGA) is a complex and rare outcome to investigate in surgical patient populations, particularly obstetric patients. We report the protocol of the Direct Reporting of Awareness in Maternity patients (DREAMY) study, illustrating how the research was designed to address practical and methodological challenges for investigating AAGA in an obstetric cohort. METHODS: This is the trial protocol of a prospective, multicentre cohort study of patients undergoing obstetric surgery under general anaesthesia. Accidental awareness during general anaesthesia will be detected using three repetitions of standardised direct questioning over 30 days, with responses indicating memories during general anaesthesia verified using structured interviews. Reports will be adjudicated, then classified, in accordance with pre-defined and pre-validated structures, including the Michigan Awareness Classification tool. Quantitative data will be collected on general anaesthesia conduct for all participants. This descriptive study is being conducted in England and aims to recruit a minimum of 2015 patients. RESULTS: The DREAMY study was prospectively registered (ClinicalTrials.gov Identifier: NCT03100396) and ethical approval granted. Participant recruitment began in May 2017 and one year follow up concluded in August 2019. Publication of the results is anticipated in 2020. CONCLUSIONS: The DREAMY study will provide data on incidence, experience and implications of AAGA for obstetric patients, using a robust methodology that will reliably detect and translate subjective AAGA reports into objective outcomes. In addition, the study is expected to improve vigilance for AAGA in participating hospitals and encourage adoption of recommendations for support of patients experiencing AAGA.

Nitrous oxide-based vs. nitrous oxide-free general anaesthesia and accidental awareness in surgical patients: an abridged Cochrane systematic review.

Accidental awareness during general anaesthesia can arise from a failure to deliver sufficient anaesthetic agent, or from a patient's resistance to an expected sufficient dose of such an agent. Awareness is 'explicit' if the patient is subsequently able to recall the event. We conducted a systematic review into the effect of nitrous oxide used as part of a general anaesthetic on the risk of accidental awareness in people over the age of five years undergoing general anaesthesia for surgery. We included 15 randomised controlled trials, 14 of which, representing a total of 3439 participants, were included in our primary analysis of the frequency of accidental awareness events. The awareness incidence rate was rare within these studies, and all were considered underpowered with respect to this outcome. The risk of bias across all studies was judged to be high, and 76% of studies failed adequately to conceal participant allocation. We considered the available evidence to be of very poor quality. There were a total of three accidental awareness events reported in two studies, one of which reported that the awareness was the result of a kink in a propofol intravenous line. There were insufficient data to conduct a meta- or sub-group analysis and there was insufficient evidence to draw outcome-related conclusions. We can, however, recommend that future studies focus on potentially high-risk groups such as obstetric or cardiac surgery patients, or those receiving neuromuscular blocking drugs or total intravenous anaesthesia.

Anesthesia management by residents does not alter the incidence of recall of tracheal extubation: a teaching hospital-based propensity score analysis / A administração de anestesia por residentes não altera a incidência de memória da extubação traqueal: uma análise de pontuação de propensão baseada no ensino hospitalar

Abstract Background and objectives: The memory of emergence from anesthesia is recognized as one type of anesthesia awareness. Apart from planed awake extubation, unintentional recall of tracheal extubation is thought to be the results of inadequate anesthesia management; therefore, the incidence can be related with the experience of anesthetists. To assess whether the incidence of recall of tracheal extubation is related to anesthetists' experience, we compared the incidence of recall of tracheal extubation between patients managed by anesthesia residents or by experienced anesthetists. Methods: This is a retrospective review of an institutional registry containing 21,606 general anesthesia cases and was conducted with the board of ethical review approval. All resident tracheal extubations were performed under anesthetists' supervision. To avoid channeling bias, propensity score analysis was used to generate a set of matched cases (resident managements) and controls (anesthetist managements), yielding 3,475 matched patient pairs. The incidence of recall of tracheal extubation was compared as primary outcomes. Results: In the unmatched population, there was no difference in the incidences of recall of tracheal extubation between resident management and anesthetist management (6.5% vs. 7.1%, p = 0.275). After propensity score matching, there was still no difference in incidences of recall of tracheal extubation (7.1% vs. 7.0%, p = 0.853). Conclusion: In conclusion, when supervised by an anesthetist, resident extubations are no more likely to result in recall than anesthetist extubations.

Resumo Justificativa e objetivos: A recordação da emergência da anestesia é reconhecida como um dos tipos de memória da anestesia. Excluindo a extubação planejada com o paciente acordado, acredita-se que a memória não intencional durante a extubação traqueal seja o resultado de manejo inadequado da anestesia; portanto, a incidência pode estar relacionada com a experiência dos anestesistas. Para avaliar se a incidência de memória durante a extubação traqueal está relacionada com a experiência dos anestesistas, comparamos a incidência de memória durante a extubação traqueal entre pacientes tratados por residentes de anestesia ou por anestesistas experientes. Métodos: Estudo retrospectivo de revisão de um registo institucional com 21.606 casos de anestesia geral, conduzido com a aprovação do Comitê de Ética. Todas as extubações traqueais foram feitas por residentes sob a supervisão de anestesistas. Para evitar o viés de canalização, a análise do índice de propensão foi usada para gerar um grupo de casos pareados (manejo por residentes) e de controles (manejo por anestesistas), obtiveram-se 3.475 pares combinados de pacientes. A incidência de memória durante a extubação traqueal foi comparada com os desfechos primários. Resultados: Na população não pareada, não houve diferença na incidência de memória durante a extubação traqueal entre o manejo feito por residentes e anestesistas (6,5% vs. 7,1%, p = 0,275). Mesmo após parear os escores de propensão, não observamos diferença na incidência de memória durante a extubação traqueal (7,1% vs. 7,0%, p = 0,853). Conclusão: Em conclusão, quando supervisionadas por um anestesista, as extubações feitas por residentes não são mais propensas a resultar em memória do que as extubações feitas por anestesistas.

Patient reported outcome of adult perioperative anaesthesia in the United Kingdom: a cross-sectional observational study.

BACKGROUND: Understanding the patient perspective on healthcare is central to the evaluation of quality. This study measured selected patient-reported outcomes after anaesthesia in order to identify targets for research and quality improvement. METHODS: This cross-sectional observational study in UK National Health Service hospitals, recruited adults undergoing non-obstetric surgery requiring anaesthesia care over a 48 h period. Within 24 h of surgery, patients completed the Bauer questionnaire (measuring postoperative discomfort and satisfaction with anaesthesia care), and a modified Brice questionnaire to elicit symptoms suggestive of accidental awareness during general anaesthesia (AAGA). Patient, procedural and pharmacological data were recorded to enable exploration of risk factors for these poor outcomes. RESULTS: 257 hospitals in 171 NHS Trusts participated (97% of eligible organisations). Baseline characteristics were collected on 16,222 patients; 15,040 (93%) completed postoperative questionnaires. Anxiety was most frequently cited as the worst aspect of the perioperative experience. Thirty-five per cent of patients reported severe discomfort in at least one domain: thirst (18.5%; 95% CI 17.8-19.1), surgical pain (11.0%; 10.5-11.5) and drowsiness (10.1%; 9.6-10.5) were most common. Despite this, only 5% reported dissatisfaction with any aspect of anaesthesia-related care. Regional anaesthesia was associated with a reduced burden of side-effects. The incidence of reported AAGA was one in 800 general anaesthetics (0.12%) CONCLUSIONS: Anxiety and discomfort after surgery are common; despite this, satisfaction with anaesthesia care in the UK is high. The inconsistent relationship between patient-reported outcome, patient experience and patient satisfaction supports using all three of these domains to provide a comprehensive assessment of the quality of anaesthesia care.

A comparison of BIS recordings during propofol-based total intravenous anaesthesia and sevoflurane-based inhalational anaesthesia in obese patients.

BACKGROUND: Intraoperative awareness is a rarely occurring phenomenon. Obesity is considered as one of the factors increasing the probability of intraoperative awareness due to problems with the dosing of anaesthetics. In a randomized prospective study we compared bispectral index (BIS) recordings during propofol-based total intravenous anaesthesia (TIVA) and sevoflurane-based inhalation anaesthesia in morbidly obese patients as a sign of possible intraoperative awareness. METHODS: 120 morbidly obese patients were randomly allocated into two subgroups: TIVA or SEVO. Propofol TIVA was performed following the Servin formula, while sevoflurane was administered based on the age of the patients. The physician administering anaesthesia was blinded to the BIS recordings while the evaluation of the depth of anaesthesia was conducted based on the clinical symptoms of adequate anaesthesia. BIS recordings were evaluated for periods of BIS > 60. Blinded structured interviews were conducted 2 hours after anaesthesia was administrated. RESULTS: The incidence of BIS > 60 occurred in 90% vs. 91.67% of patients while the mean duration of periods of BIS > 60 was 13.74 ± 21.74% vs. 14.21 ± 18.78% of the duration of anaesthesia in TIVA and SEVO groups, respectively (P > 0.05). There was no correlation between the BMI value and the duration of elevated BIS values observed during anaesthesia in both studied methods of anaesthesia, nor between the total time of anaesthesia and the duration of elevated BIS values above 60 in this study. No patient complained of intraoperative awareness when asked in the post-operative period, probably due to the administration of midasolam. CONCLUSIONS: Although the incidence of BIS > 60 are very common in obese patients, true awareness during anaesthesia infrequent in this group of patients despite the type of anaesthesia, whether intravenous or inhalation.

Is hyperlipidemia a potential protective factor against intraoperative awareness in cardiac surgery?

BACKGROUND: Intraoperative awareness is a dreaded complication that leads to psychological sequelae such as posttraumatic stress disorder, especially in patients undergoing cardiac surgery. This study investigated the incidence of awareness among patients receiving cardiac surgery and sought to identify the risk factors contributing to intraoperative awareness. METHODS: Patients with informed consent undergoing cardiac surgery from June to September in 2012 were enrolled. At least one structured interview was performed postoperatively with the modified Brice Interview Questionnaire to identify intraoperative awareness as confirmed awareness, possible awareness, and no awareness. Confirmed awareness events reported by patients were classified into different categories with the Michigan Awareness Classification Instrument. The questionnaire results were combined with the patient medical records. A logistic regression model was used to analyze the risk factors that may have led to intraoperative awareness. RESULTS: An estimated 2136 patients were included, and 1874 patients completed at least one interview. 83 patients (4.4 %) were identified as possible or confirmed awareness, among which 46 (2.5 %) reported confirmed awareness. Patients who experienced confirmed awareness were mostly of Class 1 and 2, 15 and 24 patients respectively, which represented isolated auditory and tactile perceptions. And 11 patients reported feelings of distress intraoperatively. Hyperlipidemia was associated with intraoperative awareness (OR = 0.499, 95 % CI = 0.252-0.989, p = 0.043) and using chi-square test, however, no significance was found with logistic regression. CONCLUSION: Patients undergoing cardiac surgery are at high risk for intraoperative awareness. Distress is a common feeling in patients with intraoperative awareness. Hyperlipidemia is a potential protective factor for intraoperative awareness in cardiac surgery.

A 7-Year Retrospective Multisource Analysis on the Incidence of Anesthesia Awareness With Recall in Cancer Patients: A Chance of Collaboration Between Anesthesiologists and Psycho-Oncologists for Awareness Detection.

Although randomized controlled studies reported an incidence of anesthesia awareness with recall ∼1 to 2 per 1000 (0.1-0.2%), recent data from the NAP5 study showed an incidence of only 1:19,600. Although in a prospective study many tools for anesthesia awareness detection can be used, a retrospective analysis requires a careful collection of information.The aim of the study was to evaluate the incidence of anesthesia awareness with recall in a cohort of cancer patients through a multisource retrospective analysis, and the clinical description, including the psychological outcome, of the cases detected. We also tested whether our retrospective analysis would be improved by a routinely psycho-oncological assessment. As secondary endpoints we evaluated the use of depth of anesthesia monitoring over a large cohort of patients, and the correlation between the brain monitoring and the incidence of awareness.We have carried out a 7-year retrospective analysis in a large cohort of cancer patients on the incidence of awareness with recall during general anesthesia. Of 35,595 patients assessed for eligibility, 21,099 were studied. We analyzed all data from the operative rooms' database, the anesthesia records, and from the database of the surgical divisions. In addition we examined reports from psychologists and spontaneous reports to the quality team of the hospital.Two certain cases of awareness were detected, with an incidence of 1:10,550 (0.0095%). They occurred during elective surgery, in female patients without other risk factors. One case came from the report of a psychologist. In both episodes, brain monitoring was not applied and no long-term psychological sequelae were reported.Despite the limitations, our investigation suggests that the incidence of anesthesia awareness is very low, also in a specific cohort of patients, such as the cancer patients, and even when the depth of anesthesia monitoring is rarely used. The limitations caused by both the retrospective analysis and the absence of specific tools for direct awareness detection, such as structured interviews, can be filled with an effective postoperative psychological assessment which is often of routine in a cancer center. This observation could suggest the usefulness of inserting specific questions within the psychological tools commonly used by psycho-oncologists.

[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.

Intraoperative awareness risk, anesthetic sensitivity, and anesthetic management for patients with natural red hair: a matched cohort study.

PURPOSE: The red-hair phenotype, which is often produced by mutations in the melanocortin-1 receptor gene, has been associated with an increase in sedative, anesthetic, and analgesic requirements in both animal and human studies. Nevertheless, the clinical implications of this phenomenon in red-haired patients undergoing surgery are currently unknown. METHODS: In a secondary analysis of a prospective trial of intraoperative awareness, red-haired patients were identified and matched with five control patients, and the relative risk for intraoperative awareness was determined. Overall anesthetic management between groups was compared using Hotelling's T(2) statistic. Inhaled anesthetic requirements were compared between cohorts by evaluating the relationship between end-tidal anesthetic concentration and the bispectral index with a linear mixed-effects model. Time to recovery was compared using Kaplan-Meier analysis, and differences in postoperative pain and nausea/vomiting were evaluated with Chi square tests. RESULTS: A cohort of 319 red-haired patients was matched with 1,595 control patients for a sample size of 1,914. There were no significant differences in the relative risk of intraoperative awareness (relative risk = 1.67; 95% confidence interval 0.34 to 8.22), anesthetic management, recovery times, or postoperative pain between red-haired patients and control patients. The relationship between pharmacokinetically stable volatile anesthetic concentrations and bispectral index values differed significantly between red-haired patients and controls (P < 0.001), but without clinical implications. CONCLUSION: There were no demonstrable differences between red-haired patients and controls in response to anesthetic and analgesic agents or in recovery parameters. These findings suggest that perioperative anesthetic and analgesic management should not be altered based on self-reported red-hair phenotype.

Psychological sequelae of surgery in a prospective cohort of patients from three intraoperative awareness prevention trials.

BACKGROUND: Elective surgery can have long-term psychological sequelae, especially for patients who experience intraoperative awareness. However, risk factors, other than awareness, for symptoms of posttraumatic stress disorder (PTSD) after surgery are poorly defined, and practical screening methods have not been applied to a broad population of surgical patients. METHODS: The Psychological Sequelae of Surgery study was a prospective cohort study of patients previously enrolled in the United States and Canada in 3 trials for the prevention of intraoperative awareness. The 68 patients who experienced definite or possible awareness were matched with 418 patients who denied awareness based on age, sex, surgery type, and awareness risk. Participants completed the PTSD Checklist-Specific (PCL-S) and/or a modified Mini-International Neuropsychiatric Interview telephone assessment to identify symptoms of PTSD and symptom complexes consistent with a PTSD diagnosis. We then used structural equation modeling to produce a composite PTSD score and examined potential risk factors. RESULTS: One hundred forty patients were unreachable; of those contacted, 303 (88%) participated a median of 2 years postoperatively. Forty-four of the 219 patients (20.1%) who completed the PCL-S exceeded the civilian screening cutoff score for PTSD symptoms resulting from their surgery (15 of 35 [43%] with awareness and 29 of 184 [16%] without). Nineteen patients (8.7%; 5 of 35 [14%] with awareness and 14 of 184 [7.6%] without) both exceeded the cutoff and endorsed a breadth of symptoms consistent with the Diagnostic and Statistical Manual Fourth Edition diagnosis of PTSD attributable to their surgery. Factors independently associated with PTSD symptoms were poor social support, previous PTSD symptoms, previous mental health treatment, dissociation related to surgery, perceiving that one's life was threatened during surgery, and intraoperative awareness (all P ≤ 0.017). Perioperative dissociation was identified as a potential mediator for perioperative PTSD symptoms. CONCLUSIONS: Events in the perioperative period can precipitate psychological symptoms consistent with subsyndromal and syndromal PTSD. We not only confirmed the high rate of postoperative PTSD in awareness patients but also identified a significant rate in matched nonawareness controls. Screening surgical patients, especially those with potentially mediating risk factors such as intraoperative awareness or perioperative dissociation, for postoperative PTSD symptoms with the PCL-S is practical and could promote early referral, evaluation, and treatment.

Sedation monitoring during open muscle biopsy in children by Comfort Score and Bispectral Index - a prospective analysis.

BACKGROUND: Open muscle biopsies in children are generally performed under general anesthesia. Alternatively, deep sedation and analgesia may be required. OBJECTIVES: The aim of our study was to compare the Bispectral Index (BIS) and Comfort Score (CS) with respect to their clinical significance for sedation/analgesia in children undergoing open muscle biopsy. METHODS: Thirty pediatric patients subjected to open muscle biopsy for diagnosis of their underlying disease were prospectively enrolled. Sedation/analgesia was performed in all patients using remifentanil and propofol. The patients were simultaneously monitored using the CS and BIS. RESULTS: All sedations and muscle biopsies were performed uneventfully. The CS and BIS were significantly correlated (R = 0.589; P < 0.01). Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.918 with a maximum cut-off point of BIS 70.5 (sensitivity 0.9; specificity 0.785) for adequate sedation. Sensitivity of 100% was achieved at BIS 60. Accordingly, all patients with BIS ≤60 had CS within the target range of 10-14. The BIS showed substantial intra- and interindividual variability (30 points and 58 points, respectively) during sedation, whereas CS varied only within close ranges during sedation. In 25 patients, sedatives were reduced according to low BIS values (<60). No unintended anesthesia awareness was noted during the study period. CONCLUSION: Bispectral Index provides an additional helpful tool to guide sedation/analgesia in minor surgical procedures in children. BIS values ≤60 correlated with sufficient depth of sedation and prevented unintended awareness. Additionally, BIS measurement allowed for distinct regulation of depth of sedation without prolonged sedation/analgesia due to unintended overdose.

Alerting thresholds for the prevention of intraoperative awareness with explicit recall: a secondary analysis of the Michigan Awareness Control Study.

BACKGROUND: Intraoperative awareness with explicit recall is a potentially devastating complication of surgery that has been attributed to low anaesthetic concentrations in the vast majority of cases. Past studies have proposed the determination of an adequate dose for general anaesthetics that could be used to alert providers of potentially insufficient anaesthesia. However, there have been no systematic analyses of appropriate thresholds to develop population-based alerting algorithms for preventing intraoperative awareness. OBJECTIVE: To identify a threshold for intraoperative alerting that could be applied for the prevention of awareness with explicit recall. DESIGN: Secondary analysis of a randomised controlled trial (Michigan Awareness Control Study). SETTING: Three hospitals at a tertiary care centre in the USA. PATIENTS: Unselected patients presenting for surgery under general anaesthesia. INTERVENTIONS: Alerts based on end-tidal anaesthetic concentration or bispectral index values. MAIN OUTCOME MEASURES: Using case and outcomes data from the primary study, end-tidal anaesthetic concentration and bispectral index values were analysed using Youden's index and c-statistics derived from a receiver operating characteristic curve to determine a specific alerting threshold for the prevention of awareness. RESULTS: No single population-based threshold that maximises sensitivity and specificity could be identified for the prevention of intraoperative awareness, using either anaesthetic concentration or bispectral index values. The c-statistic for anaesthetic concentration was 0.431 ±â€Š0.046, and 0.491 ±â€Š0.056 for bispectral index values. CONCLUSION: We could not derive a single population-based alerting threshold for the prevention of intraoperative awareness using either anaesthetic concentration or bispectral index values. These data indicate a need to move towards individualised alerting strategies in the prevention of intraoperative awareness. TRIAL REGISTRATION: Primary trial registration (Michigan Awareness Control Study) ClinicalTrials.gov identifier: NCT00689091.

The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors.

We present the main findings of the 5th National Audit Project on accidental awareness during general anaesthesia. Incidences were estimated using reports of accidental awareness as the numerator, and a parallel national anaesthetic activity survey to provide denominator data. The incidence of certain/probable and possible accidental awareness cases was ~1:19 600 anaesthetics (95% CI 1:16 700-23 450). However, there was considerable variation across subtypes of techniques or subspecialties. The incidence with neuromuscular blockade was ~1:8200 (1:7030-9700), and without it was ~1:135 900 (1:78 600-299 000). The cases of accidental awareness during general anaesthesia reported to 5th National Audit Project were overwhelmingly cases of unintended awareness during neuromuscular blockade. The incidence of accidental awareness during caesarean section was ~1:670 (1:380-1300). Two thirds (82, 66%) of cases of accidental awareness experiences arose in the dynamic phases of anaesthesia, namely induction of and emergence from anaesthesia. During induction of anaesthesia, contributory factors included: use of thiopental; rapid sequence induction; obesity; difficult airway management; neuromuscular blockade; and interruptions of anaesthetic delivery during movement from anaesthetic room to theatre. During emergence from anaesthesia, residual paralysis was perceived by patients as accidental awareness, and commonly related to a failure to ensure full return of motor capacity. One third (43, 33%) of accidental awareness events arose during the maintenance phase of anaesthesia, most due to problems at induction or towards the end of anaesthesia. Factors increasing the risk of accidental awareness included: female sex; age (younger adults, but not children); obesity; anaesthetist seniority (junior trainees); previous awareness; out-of-hours operating; emergencies; type of surgery (obstetric, cardiac, thoracic); and use of neuromuscular blockade. The following factors were not risk factors for accidental awareness: ASA physical status; race; and use or omission of nitrous oxide. We recommend that an anaesthetic checklist, to be an integral part of the World Health Organization Safer Surgery checklist, is introduced as an aid to preventing accidental awareness. This paper is a shortened version describing the main findings from 5th National Audit Project - the full report can be found at http://www.nationalauditprojects.org.uk/NAP5_home#pt.

5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods, and analysis of data.

BACKGROUND: Accidental awareness during general anaesthesia (AAGA) with recall is a potentially distressing complication of general anaesthesia that can lead to psychological harm. The 5th National Audit Project (NAP5) was designed to investigate the reported incidence, predisposing factors, causality, and impact of accidental awareness. METHODS: A nationwide network of local co-ordinators across all the UK and Irish public hospitals reported all new patient reports of accidental awareness to a central database, using a system of monthly anonymized reporting over a calendar year. The database collected the details of the reported event, anaesthetic and surgical technique, and any sequelae. These reports were categorized into main types by a multidisciplinary panel, using a formalized process of analysis. RESULTS: The main categories of accidental awareness were: certain or probable; possible; during sedation; on or from the intensive care unit; could not be determined; unlikely; drug errors; and statement only. The degree of evidence to support the categorization was also defined for each report. Patient experience and sequelae were categorized using current tools or modifications of such. CONCLUSIONS: The NAP5 methodology may be used to assess new reports of AAGA in a standardized manner, especially for the development of an ongoing database of case reporting. This paper is a shortened version describing the protocols, methods, and data analysis from NAP5--the full report can be found at http://www.nationalauditprojects.org.uk/NAP5_home.