PURPOSE OF REVIEW: Head-mounted displays (HMDs) are head-worn display devices that project an information display over the wearer's field of view. This article reviews a recent program of research that investigates the advantages and disadvantages of monitoring with HMDs, and discusses the design considerations and implementation issues that must be addressed before HMDs can be clinically adopted. RECENT FINDINGS: HMDs let anesthesiologists spend a larger proportion of their time in the operating room looking towards the patient and surgical field, and a correspondingly smaller proportion of time looking at the standard monitors. Anesthesiologists can detect patient events faster with an HMD when they are busy performing procedures, but not during normal monitoring. There was no evidence of anesthesiologists' performance or monitoring behavior being affected by perceptual issues with the HMD, and no evidence that more events were missed with the HMD due to inattentional blindness. SUMMARY: Anesthesiologists may be able to monitor their patients more effectively when an HMD is used in conjunction with existing monitors, but several engineering and implementation issues need to be resolved before HMDs can be adopted in practice. Further research is needed on the design of information displays for HMDs.

PURPOSE OF REVIEW: We outline and discuss recent work on auditory displays, covering both auditory alarms that indicate technical or physiological threshold levels and informative auditory displays that provide a continuous awareness of a patient's well being. RECENT FINDINGS: The struggle to make auditory alarms informative proceeds with work on two fronts. In one approach, researchers are developing and evaluating auditory alarm displays to indicate the source and urgency of off-normal states and are relying on the emergence of smart software algorithms to reduce the false-positive rate. In a complementary approach, other researchers are providing information about the patient's well being in normal as well as abnormal states, generalizing the advantages of variable-tone pulse oximetry to other systems and other auditory display formats. In either approach, a multidisciplinary team is essential in the design and evaluation of auditory displays. Because informative auditory displays may subtly change clinical practice, there are repercussions for training. SUMMARY: Auditory display in anesthesia can extend well beyond auditory alarms to displays that give the anesthesiologist a continuous peripheral awareness of patient well being. Much more rigorous approaches should be taken to evaluating auditory displays so they add information rather than noise.

Sonification-representing data in sound-is a potential method for supporting human operators who have to monitor dynamic processes. Previous research has investigated a limited number of sound dimensions and has not systematically investigated the impact of dimensional interactions on sonification effectiveness. In three experiments the authors investigated accuracy for identifying changes in six target auditory dimensions of a continuous pulse stream under three conditions: no distractor, one distractor, and five distractors. In Experiment 1 amplitude, frequency, harmonics, speed, tremolo (cycles per pulse), and width were tested. Accuracy and patterns of interaction between the dimensions were mapped. In Experiment 2 the same dimensions were tested but tremolo was operationalized as cycles per second (Hz). The patterns of interaction between the temporal dimensions differed from Experiment 1. In Experiment 3 the amplitude contour of the pulse stream was changed. The dimensions tested were amplitude, frequency, formants, speed, tremolo (cycles per period), and width. Results showed low accuracy for formants and many interactions, both positive and negative between the dimensions. The authors interpret the results in terms of theories of perceptual interference in auditory dimensions.(PsycINFO Database Record (c) 2009 APA, all rights reserved).

BACKGROUND: Researchers in healthcare have begun to investigate interruptions extensively, given evidence for the adverse effects of work interruptions in other domains and given the highly interruptive hospital environment. In this paper, we reviewed literature on interruptions in critical care and medication dispensing settings in search of evidence for a relationship between interruptions and adverse events. METHODS: The literature search included the databases MEDLINE, CINAHL+Pre CINHAL, Health Sources: Nursing Academic Edition, EMBASE, PsycINFO, ISI Web of Science and Ergonomics Abstracts. The paper titles and abstracts were subsequently reviewed. After the initial search, we reviewed paper titles and abstracts to define the subset for review. RESULTS: We currently lack evidence in healthcare of the extent to which interruptions lead to adverse effects. The lack of evidence may be due to the descriptive rather than causal nature of most studies, the lack of theory motivating investigations of the relationship, the fact that healthcare is a complex and varied domain, and inadequate conceptualizations of accident aetiology. We identify two recent accident theories in which the relationship between activity and medical errors is complex, indicating that even when it is sought, causal evidence is hard to find. DISCUSSION: Future research on interruptions in healthcare settings should focus on the following. First, prospective memory research and distributed cognition can provide a theoretical background for understanding the impact of interruptions and so could provide guidance for future empirical research on interruptions and the planning of actions in healthcare. Second, studying how interruptions are successfully rather than unsuccessfully overcome may better help us understand their effects. Third, because interruptions almost always have positive and adverse effects, more appropriate dependent variables could be chosen.

Many healthcare ICT innovations fail in practice because of a failure to take into account user needs. User needs should be identified broadly, encompassing different levels of organization of the healthcare system and different stakeholder concerns. Full-scale simulators are starting to be used to help in the design and evaluation of novel biomedical devices and displays. Although promising, simulators have significant technical and operational limitations for this purpose and they do not address important aspects of the sociotechnical systems context in which healthcare ICT will be embedded. This argument is illustrated with a case study in which advanced auditory displays for patient monitoring were successfully evaluated in a full-scale patient simulator, but many further questions remain prior to successful translation to practice.

OBJECTIVE: We explore how accurately and quickly nurses can identify melodic medical equipment alarms when no mnemonics are used, when alarms may overlap, and when concurrent tasks are performed. BACKGROUND: The international standard IEC 60601-1-8 (International Electrotechnical Commission, 2005) has proposed simple melodies to distinguish seven alarm sources. Previous studies with nonmedical participants reveal poor learning of melodic alarms and persistent confusions between some of them. The effects of domain expertise, concurrent tasks, and alarm overlaps are unknown. METHOD: Fourteen intensive care and general medical unit nurses learned the melodic alarms without mnemonics in two sessions on separate days. In the second half of Day 2 the nurses identified single alarms or pairs of alarms played in sequential, partially overlapping, or nearly completely overlapping configurations. For half the experimental blocks nurses performed a concurrent mental arithmetic task. RESULTS: Nurses' learning was poor and was no better than the learning of nonnurses in a previous study. Nurses showed the previously noted confusions between alarms. Overlapping alarms were exceptionally difficult to identify. The concurrent task affected response time but not accuracy. CONCLUSION: Because of a failure of auditory stream segregation, the melodic alarms cannot be discriminated when they overlap. Directives to sequence the sounding of alarms in medical electrical equipment must be strictly adhered to, or the alarms must redesigned to support better auditory streaming. APPLICATION: Actual or potential uses of this research include the implementation of IEC 60601-1-8 alarms in medical electrical equipment.

OBJECTIVE: We perform a critical review of research on mental workload in en route air traffic control (ATC). We present a model of operator strategic behavior and workload management through which workload can be predicted within ATC and other complex work systems. BACKGROUND: Air traffic volume is increasing worldwide. If air traffic management organizations are to meet future demand safely, better models of controller workload are needed. METHOD: We present the theoretical model and then review investigations of how effectively traffic factors, airspace factors, and operational constraints predict controller workload. RESULTS: Although task demand has a strong relationship with workload, evidence suggests that the relationship depends on the capacity of the controllers to select priorities, manage their cognitive resources, and regulate their own performance. We review research on strategies employed by controllers to minimize the control activity and information-processing requirements of control tasks. CONCLUSION: Controller workload will not be effectively modeled until controllers' strategies for regulating the cognitive impact of task demand have been modeled. APPLICATION: Actual and potential applications of our conclusions include a reorientation of workload modeling in complex work systems to capture the dynamic and adaptive nature of the operator's work. Models based around workload regulation may be more useful in helping management organizations adapt to future control regimens in complex work systems.

OBJECTIVE: We explore whether ecological interface design (EID) principles can be applied to the design of an auditory display for anesthesia monitoring. BACKGROUND: EID examples focus almost exclusively on visual displays. In the anesthesia work environment, however, auditory displays may provide better individual and team awareness of patient state. METHOD: Using a work domain analysis of physiological monitoring in anesthesia, we identify information to display. Using the skills, rules, and knowledge distinction we identify cognitive control needed. Using semantic mapping we map physiological variables and constraints to auditory dimensions. RESULTS: EID principles do not address when information should be displayed and to whom. An attentional mapping stage helps to specify answers to these questions so that a workable auditory display for anesthesia monitoring is achieved. CONCLUSION: EID principles of representing work domain functional structure and minimizing resource-demanding cognitive control are necessary but insufficient to specify requirements for an effective auditory display. Also needed are analyses of control tasks, strategies, and the social organization of work. Such analyses are an integral part of the broader cognitive work analysis framework from which EID emerged. APPLICATION: Actual or potential uses of this research include the design of displays that support continuous peripheral awareness in collaborative multimodal work environments.

A vision of the future of intraoperative monitoring for anesthesia is presented-a multimodal world based on advanced sensing capabilities. I explore progress towards this vision, outlining the general nature of the anesthetist's monitoring task and the dangers of attentional capture. Research in attention indicates different kinds of attentional control, such as endogenous and exogenous orienting, which are critical to how awareness of patient state is maintained, but which may work differently across different modalities. Four kinds of medical monitoring displays are surveyed:(1) integrated visual displays,(2) head-mounted displays,(3) advanced auditory displays and (4) auditory alarms. Achievements and challenges in each area are outlined. In future research, we should focus more clearly on identifying anesthetists' information needs and we should develop models of attention in different modalities and across different modalities that are more capable of guiding design.

PURPOSE OF REVIEW: We outline and discuss recent work on auditory displays, covering both auditory alarms that indicate technical or physiological threshold levels and informative auditory displays that provide a continuous awareness of a patient's well being. RECENT FINDINGS: The struggle to make auditory alarms informative proceeds with work on two fronts. In one approach, researchers are developing and evaluating auditory alarm displays to indicate the source and urgency of off-normal states and are relying on the emergence of smart software algorithms to reduce the false-positive rate. In a complementary approach, other researchers are providing information about the patient's well being in normal as well as abnormal states, generalizing the advantages of variable-tone pulse oximetry to other systems and other auditory display formats. In either approach, a multidisciplinary team is essential in the design and evaluation of auditory displays. Because informative auditory displays may subtly change clinical practice, there are repercussions for training. SUMMARY: Auditory display in anesthesia can extend well beyond auditory alarms to displays that give the anesthesiologist a continuous peripheral awareness of patient well being. Much more rigorous approaches should be taken to evaluating auditory displays so they add information rather than noise.

BACKGROUND: Head-mounted displays (HMDs) can help anesthesiologists with intraoperative monitoring by keeping patients' vital signs within view at all times, even while the anesthesiologist is busy performing procedures or unable to see the monitor. The anesthesia literature suggests that there are advantages of HMD use, but research into head-up displays in the cockpit suggests that HMDs may exacerbate inattentional blindness (a tendency for users to miss unexpected but salient events in the field of view) and may introduce perceptual issues relating to focal depth. We investigated these issues in two simulator-based experiments. METHODS: Experiment 1 investigated whether wearing a HMD would affect how quickly anesthesiologists detect events, and whether the focus setting of the HMD (near or far) makes any difference. Twelve anesthesiologists provided anesthesia in three naturalistic scenarios within a simulated operating theater environment. There were 24 different events that occurred either on the patient monitor or in the operating room. Experiment 2 investigated whether anesthesiologists physically constrained by performing a procedure would detect patient-related events faster with a HMD than without. Twelve anesthesiologists performed a complex simulated clinical task on a part-task endoscopic dexterity trainer while monitoring the simulated patient's vital signs. All participants experienced four different events within each of two scenarios. RESULTS: Experiment 1 showed that neither wearing the HMD nor adjusting the focus setting reduced participants' ability to detect events (the number of events detected and time to detect events). In general, participants spent more time looking toward the patient and less time toward the anesthesia machine when they wore the HMD than when they used standard monitoring alone. Participants reported that they preferred the near focus setting. Experiment 2 showed that participants detected two of four events faster with the HMD, but one event more slowly with the HMD. Participants turned to look toward the anesthesia machine significantly less often when using the HMD. When using the HMD, participants reported that they were less busy, monitoring was easier, and they believed they were faster at detecting abnormal changes. CONCLUSIONS: The HMD helped anesthesiologists detect events when physically constrained, but not when physically unconstrained. Although there was no conclusive evidence of worsened inattentional blindness, found in aviation, the perceptual properties of the HMD display appear to influence whether events are detected. Anesthesiologists wearing HMDs should self-adjust the focus to minimize eyestrain and should be aware that some changes may not attract their attention. Future areas of research include developing principles for the design of HMDs, evaluating other types of HMDs, and evaluating the HMD in clinical contexts.

Sonification-representing data in sound-is a potential method for supporting human operators who have to monitor dynamic processes. Previous research has investigated a limited number of sound dimensions and has not systematically investigated the impact of dimensional interactions on sonification effectiveness. In three experiments the authors investigated accuracy for identifying changes in six target auditory dimensions of a continuous pulse stream under three conditions: no distractor, one distractor, and five distractors. In Experiment 1 amplitude, frequency, harmonics, speed, tremolo (cycles per pulse), and width were tested. Accuracy and patterns of interaction between the dimensions were mapped. In Experiment 2 the same dimensions were tested but tremolo was operationalized as cycles per second (Hz). The patterns of interaction between the temporal dimensions differed from Experiment 1. In Experiment 3 the amplitude contour of the pulse stream was changed. The dimensions tested were amplitude, frequency, formants, speed, tremolo (cycles per period), and width. Results showed low accuracy for formants and many interactions, both positive and negative between the dimensions. The authors interpret the results in terms of theories of perceptual interference in auditory dimensions.(PsycINFO Database Record (c) 2009 APA, all rights reserved).

OBJECTIVE: To introduce a sound synthesis tool for human EEG rhythms that is applicable in real time. METHODS: We design an event-based sonification which suppresses irregular background and highlights normal and pathologic rhythmic activity. RESULTS: We generated sound examples with rhythms from well-known epileptic disorders and find stereotyped rhythmic auditory objects in single channel and stereo display from generalized spike-wave runs. For interictal activity, we were able to separate focal rhythms from background activity and thus enable the listener to perceive its frequency, duration, and intensity while monitoring. CONCLUSIONS: The proposed event-based sonification allows quick detection and identification of different types of rhythmic EEE events in real time and can thus be used to complement visual displays in monitoring and EEG feedback tasks. SIGNIFICANCE: The significance of the work lies in the fact that it can be implemented for on-line monitoring of clinical EEG and for EEG feedback applications where continuous screen watching can be substituted or improved by the auditory information stream.

We reviewed the use of advanced display technologies for monitoring in anesthesia. Researchers are investigating displays that integrate information and that, in some cases, also deliver the results continuously to the anesthesiologist. Integrated visual displays reveal higher-order properties of patient state and speed in responding to events, but their benefits under an intensely timeshared load is unknown. Head-mounted displays seem to shorten the time to respond to changes, but their impact on peripheral awareness and attention is unknown. Continuous auditory displays extending pulse oximetry seem to shorten response times and improve the ability to timeshare other tasks, but their integration into the already noisy operative environment still needs to be tested. We reviewed the advantages and disadvantages of the three approaches, drawing on findings from other fields, such as aviation, to suggest outcomes where there are still no results for the anesthesia context. Proving that advanced patient monitoring displays improve patient outcomes is difficult, and a more realistic goal is probably to prove that such displays lead to better situational awareness, earlier responding, and less workload, all of which keep anesthesia practice away from the outer boundaries of safe operation.

Information displays commonly use 2-D and 3-D objects even though the numbers represented are 1-D. This practice may be problematic because the psychophysical relation between perceived and physical magnitudes is generally nonlinear for areas and volumes. Nonetheless, this research shows that apparent 2-D and 3-D objects can produce linear psychophysical functions if only one dimension shows variation. Processing time increases with the number of dimensions in the objects that show variation, not with the apparent dimensionality. Indeed, when only one dimension showed variation, apparent 3-D objects were judged more quickly than were apparent 2-D or 1-D objects. These results present a challenge for computational models of size perception and have implications for the design of information displays. Actual or potential applications of this research include the design and use of statistical graphs and information displays; objects that display variation in more than one dimension should not be used to represent single (1-D) numerical variables if they are to be judged accurately and rapidly.

It cannot be overemphasized that a piece of electrical equipment is not capable of replacing a vigilant, well-trained clinician. As monitoring devices become more sophisticated, the potential for artifact or misinterpretation increases. When applied appropriately, operated properly, and interpreted correctly, however, the monitors afford the patient the best possible outcome.