Chaos-modified detrended moving average methodology for monitoring the depth of anaesthesia

This paper proposes a new method to monitor the depth of anaesthesia (DoA) based on the EEG signal. This approach firstly uses discrete wavelet transform (DWT) to to remove the spikes and the low frequency noise from raw EEG signals. After de-noising the EEG signals, the modified Hurst parameter is proposed with two new indices (CDoA and CsDoA), to estimate the anaesthesia states of the patients. To reduce the fluctuation of the new DoA index, a combination of Modified Chaos and Modifying Detrended Moving Average is used (MC-DMA). Analyses of variance (ANOVA) for C-MDMA and BIS distributions are presented The results indicate that the C-MDMA distributions at each anaesthesia state level are significantly different and the C-MDMA can distinguish five depths of anaesthesia. Compared with BIS trends, MC-DMA trend is close to BIS trend covering the whole scale from 100 to 0 with a full recording time

The Use of Audio in Minimal Access Surgery

In minimal access surgery (MAS) (also known as minimally invasive surgery), operations are carried out by making small incisions in the skin and inserting special apparatus into potential body cavities through those incisions. Laparoscopic MAS procedures are conducted in the patient’s abdomen. The aim of MAS is faster recovery, shorter hospitalisation and fewer major post-operative complications; all resulting in lower societal cost with better patient acceptability. The technique is markedly dependent on supporting technologies for vision, instrumentation, energy delivery, anaesthesia, and monitoring. However, in practice, much MAS continues to take longer and be associated with an undesirable frequency of unwanted minor (or occasionally major) mishaps. Many of these difficulties result precisely from the complexity and mal-adaptation of the additional technology and from lack of familiarity with it. A survey of South East England surgeons showed the two main stress factors on surgeons to be the technical difficulty of the procedure and time pressures placed on the surgeon by third parties. Many of the problems associated with MAS operations are linked to the control and monitoring of the equipment. This paper describes work begun to explore ergonomic enhancements to laparoscopic operating technology that could result in faster and safer laparoscopic operations, less surgeon stress and reduce dependence on ancillary staff. Auditory displays have been used to communicate complex information to users in a modality that is complementary to the visual channel. This paper proposes the development of a control and feedback system that will make use of auditory displays to improve the amount of information that can be communicated to the surgeon and his assistant without overloading the visual channel. Control of the system would be enhanced by the addition of voice input to allow the surgeon direct control

Occupational Exposure to Halogenated Anaesthetic Gases in Hospitals: A Systematic Review of Methods and Techniques to Assess Air Concentration Levels

Objective During the induction of gaseous anaesthesia, waste anaesthetic gases (WAGs) can be released into workplace air. Occupational exposure to high levels of halogenated WAGs may lead to adverse health effects; hence, it is important to measure WAGs concentration levels to perform risk assessment and for health protection purposes. Methods A systematic review of the scientific literature was conducted on two different scientific databases (Scopus and PubMed). A total of 101 studies, focused on sevoflurane, desflurane and isoflurane exposures in hospitals, were included in this review. Key information was extracted to provide (1) a description of the study designs (e.g., monitoring methods, investigated occupational settings, anaesthetic gases in use); (2) an evaluation of time trends in the measured concentrations of considered WAGs; (3) a critical evaluation of the sampling strategies, monitoring methods and instruments used. Results Environmental monitoring was prevalent (68%) and mainly used for occupational exposure assessment during adult anaesthesia (84% of cases). Real-time techniques such as photoacoustic spectroscopy and infrared spectrophotometry were used in 58% of the studies, while off-line approaches such as active or passive sampling followed by GC-MS analysis were used less frequently (39%). Conclusions The combination of different instrumental techniques allowing the collection of data with different time resolutions was quite scarce (3%) despite the fact that this would give the opportunity to obtain reliable data for testing the compliance with 8 h occupational exposure limit values and at the same time to evaluate short-term exposures

Crisis management during anaesthesia: problems associated with drug administration during anaesthesia

© 2005 BMJ Publishing Group Ltd.BACKGROUND: Modern anaesthetic practice relies upon the administration of a wide range of potent drugs given by a variety of routes, at times in haste or under conditions of stress. Problems associated with drug administration make up the largest group of incidents reported during anaesthesia, with outcomes including major morbidity and death. It was decided to examine the role of a structured approach to the diagnosis and management of drug problems under anaesthesia. OBJECTIVES: To examine the role of a previously described core algorithm "COVER ABCD–A SWIFT CHECK", supplemented by a specific sub-algorithm for drug problems, in the detection and management of drug problems occurring in association with anaesthesia. METHODS: The potential performance of this structured approach for the relevant incidents among the first 4000 incidents reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual performances as reported by the anaesthetists involved. RESULTS: Among the first 4000 reports received by AIMS there were 1199 reports which detailed 1361 incidents involving the use of drugs. Contributing factors named included errors of judgement (20%), lack of attention (17%), and drugs deemed to have been given in haste. Major morbidity or prolonged stay ensued in over one quarter of reports and 15 patients (1.25%) died. Drug overdose, side effects, and allergic reactions accounted for the majority of serious outcomes. CONCLUSION: It was judged that the use of the COVER–ABCD algorithm during the course of an anaesthetic, properly applied, would prevent many drug related incidents from occurring. The sub-algorithm presented here provides a systematic framework for detecting the causes of drug related incidents.A D Paix, M F Bullock, W B Runciman and J A Williamso

Clinical factors associated with the non-utilization of an anaesthesia incident reporting system

Background Incident reporting is a widely recommended method to measure undesirable events in anaesthesia. Under-utilization is a major weakness of voluntary incident reporting systems. Little is known about factors influencing reporting practices, particularly the clinical environment, anaesthesia team composition, severity of the incident, and perceived risk of litigation. The purpose of this study was to assess each of these, using an existing anaesthesia database. Methods We performed a retrospective cohort study and analysed 46 207 surgical patients. We used multivariate analysis to identify factors associated with the non-utilization of the reporting system. Results We found that in 7022 (15.1%) of the procedures performed, the incident reporting system was not used. Factors associated with the non-use of the system were regional anaesthesia/local anaesthesia, odds ratio (OR) 1.64 [95% confidence interval (CI) 1.03-2.62], emergency procedures OR 1.15 (95% CI: 1.05-1.27), and a consultant anaesthetist working without a trainee, OR 1.71 (95% CI: 1.03-2.82). In contrast, factors such as longer duration of surgery, OR 0.85 (95% CI: 0.76-0.94), the presence of a senior anaesthesia trainee, OR 0.86 (95% CI: 0.81-0.92), and the occurrence of severe complications with a high risk of litigation (i.e. death, nerve injuries) were less associated with a non-use of the reporting system, OR 0.65 (95% CI: 0.44-0.97). Team composition and time of day had no measurable impact on reporting practices. Conclusions Clinical factors play a significant role in the utilization of an anaesthesia incident reporting system and more particularly, severity of complications and higher liability risks which appear more as incentives than barriers to incident reportin

Shaped by Design "How User-Interface Design Influences Medical Decision Making: The Role of Monitoring Equipment in Anesthetic Practice"

abstract: Objective: The aim of this research is to uncover, via a comprehensive cross study analysis, data patterns that could potentially point to a positive correlation between two main variables: anesthetic monitoring equipment and anesthetic decision making. Of particular interest is the equipment's monitor screen and the extent to which its user interface design influences anesthetic situation awareness (SA) and hence, decision making. It is hypothesized that poor anesthetic diagnosis from inadequate SA may be largely attributable to patient data displays lacking in human factors design considerations. Methods: A systematic search was conducted of existing empirical studies pertaining to patient physiologic monitoring that spanned across interrelated domains, namely, ergonomics, medical informatics, visual computing, cognitive psychology, human factors, clinical monitoring, intensive care medicine, and intelligent systems etc. all published in scholarly research journals between 1970 to August 2012. Anesthetic-related keywords were queried i.e. anesthetic mishaps, patient physiological data displays, anesthetic vigilance etc. (found in Appendix A). This approach yielded a few thousand results, of which 65 empirical studies were pulled. Further extraction of articles having direct connection to the use of data displays within the anesthetic context produced a total of 20 empirical studies. These studies were grouped under two broad categories of Monitoring and Monitors whereby factors directly contributing to the studies' results were identified with the aim to find emerging themes that provide insights involving interface design and medical decision making. Results: There is a direct correlation between user-interface design and decision making. The situation awareness (SA) required for decision making heavily relies upon data displays oriented towards information extraction and integration. In the systematic assessment of empirical studies, it is undeniable how strikingly prominent visual attributes show up as contributing factors to subjects' enhanced performance in the studies. Conclusions: How and to what users direct their perceptual and cognitive resources necessarily influence their perception of the environment, and by extension, their development of situation awareness (SA). Although patient monitoring equipment employed in anesthetic practice has proven to be indispensable in quality patient care, graphical representations of patient data is still far from optimal in the clinical setting. User-interfaces that lend decision support to facilitate SA and subsequent decision making is critical in crisis management.Dissertation/ThesisM.S.D. Design 201