Simon A. Jenkins

Advanced Auditory Displays and Head-Mounted Displays: Advantages and Disadvantages for Monitoring by the Distracted Anesthesiologist

BACKGROUND:In a full-scale anesthesia simulator study we examined the relative effectiveness of advanced auditory displays for respiratory and blood pressure monitoring and of head-mounted displays (HMDs) as supplements to standard intraoperative monitoring. METHODS:Participants were 16 residents and attendings. While performing a reading-based distractor task, participants supervised the activities of a resident (an actor) who they were told was junior to them. If participants detected an event that could eventually harm the simulated patient, they told the resident, pressed a button on the computer screen, and/or informed a nearby experimenter. Participants completed four 22-min anesthesia scenarios. Displays were presented in a counterbalanced order that varied across participants and included: (1) Visual (visual monitor with variable-tone pulse oximetry), (2) HMD (Visual plus HMD), (3) Audio (Visual plus auditory displays for respiratory rate, tidal volume, end-tidal CO2, and noninvasive arterial blood pressure), and (4) Both (Visual plus HMD plus Audio). RESULTS:Participants detected significantly more events with Audio (mean = 90%, median = 100%, P < 0.02) and Both (mean = 92%, median = 100%, P < 0.05) but not with HMD (mean = 75%, median = 67%, ns) compared with the Visual condition (mean = 52%, median = 50%). For events detected, there was no difference in detection times across display conditions. Participants self-rated monitoring as easier in the HMD, Audio and Both conditions and their responding as faster in the HMD and Both conditions than in the Visual condition. CONCLUSIONS:Advanced auditory displays help the distracted anesthesiologist maintain peripheral awareness of a simulated patients status, whereas a HMD does not significantly improve performance. Further studies should test these findings in other intraoperative contexts.

Interruptions and blood transfusion checks: lessons from the simulated operating room.

Interruptions occur frequently in the operating room with both positive and negative consequences. Interruptions can distract anesthesiologists from safety-critical tasks, such as the pretransfusion blood check. In a simulated operating room, 12 anesthesiologists requested blood as part of a “bleeding patient” scenario. They were distracted while their assistant accepted delivery of the product and began transfusing without performing the standard check. Anesthesiologists who immediately engaged with the interruption failed to notice the omission, whereas those who rejected or deferred the interruption all noted and remedied the omitted check (P < 0.05). We discuss the role of displays and strategies on safety.

Monitoring with Head-Mounted Displays: Performance and Safety in a Full-Scale Simulator and Part-Task Trainer

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.

Monitoring with Head-Mounted Displays in General Anesthesia: A Clinical Evaluation in the Operating Room

BACKGROUND:Patient monitors in the operating room are often positioned where it is difficult for the anesthesiologist to see them when performing procedures. Head-mounted displays (HMDs) can help anesthesiologists by superimposing a display of the patients vital signs over the anesthesiologists field of view. Simulator studies indicate that by using an HMD, anesthesiologists can spend more time looking at the patient and less at the monitors. We performed a clinical evaluation testing whether this finding would apply in practice. METHODS:Six attending anesthesiologists provided anesthesia to patients undergoing rigid cystoscopy. Each anesthesiologist performed 6 cases alternating between standard monitoring using a Philips IntelliVue™ MP70 and standard monitoring plus a Microvision Nomad™ ND2000 HMD. The HMD interfaced wirelessly with the MP70 monitor and displayed waveform and numerical vital signs data. Video was recorded during all cases and analyzed to determine the percentage of time, frequency, and duration of looks at the anesthesia workstation and at the patient and surgical field during various anesthetic phases. Differences between the display conditions were tested for significance using repeated-measures analysis of variance. RESULTS:Video data were collected from 36 cases that ranged from 17 to 75 minutes in duration (median 31 minutes). When participants were using the HMD, compared with standard monitoring, they spent less time looking toward the anesthesia workstation (21.0% vs 25.3%, P = 0.003) and more time looking toward the patient and surgical field (55.9% vs 51.5%, P = 0.014). The HMD had no effect on either the frequency of looks or the average duration of looks toward the patient and surgical field or toward the anesthesia workstation. CONCLUSIONS:An HMD of patient vital signs reduces anesthesiologists’ surveillance of the anesthesia workstation and allows them to spend more time monitoring their patient and surgical field during normal anesthesia. More research is needed to determine whether the behavioral changes can lead to improved anesthesiologist performance in the operating room.

University of Queensland vital signs dataset: Development of an accessible repository of anesthesia patient monitoring data for research

BACKGROUND: Data recorded from the devices used to monitor a patients vital signs are often used in the development of displays, alarms, and information systems, but high-resolution, multiple-parameter datasets of anesthesia monitoring data from patients during anesthesia are often difficult to obtain. Existing databases have typically been collected from patients in intensive care units. However, the physical state of intensive care patients is dissimilar to those undergoing surgery, more frequent and marked changes to cardiovascular and respiratory variables are seen in operating room patients, and additional and highly relevant information to anesthesia (e.g., end-tidal agent monitoring, etc.) is omitted from these intensive care databases. We collected a set of high-quality, high-resolution, multiple-parameter monitoring data suitable for anesthesia monitoring research. METHODS: Vital signs data were recorded from patients undergoing anesthesia at the Royal Adelaide Hospital. Software was developed to capture, time synchronize, and interpolate vital signs data from Philips IntelliVue MP70 and MP30 patient monitors and Datex-Ohmeda Aestiva/5 anesthesia machines into 10 millisecond resolution samples. The recorded data were saved in a variety of accessible file formats. RESULTS: Monitoring data were recorded from 32 cases (25 general anesthetics, 3 spinal anesthetics, 4 sedations) ranging in duration from 13 minutes to 5 hours (median 105 min). Most cases included data from the electrocardiograph, pulse oximeter, capnograph, noninvasive arterial blood pressure monitor, airway flow, and pressure monitor and, in a few cases, the Y-piece spirometer, electroencephalogram monitor, and arterial blood pressure monitor. Recorded data were processed and saved into 4 file formats: (1) comma-separated values text files with full numerical and waveform data, (2) numerical parameters recorded in comma-separated values files at 1-second intervals, (3) graphical plots of all waveform data in a range of resolutions as Portable Network Graphics image files, and (4) graphical overview plots of numerical data for entire cases as Portable Network Graphics and Scalable Vector Graphics files. The complete dataset is freely available online via doi:102.100.100/6914 and has been listed in the Australian National Data Service Collections Registry. DISCUSSION: The present dataset provides clinical anesthesia monitoring data from entire surgical cases where patients underwent anesthesia, includes a wide range of vital signs variables that are commonly monitored during surgery, and is published in accessible, user-friendly file formats. The text and image file formats let researchers without engineering or computer science backgrounds easily access the data using standard spreadsheet and image browsing software. In future work, monitoring data should be collected from a wider range and larger number of cases, and software tools are needed to support searching and navigating the database.

Auditory displays in anesthesiology

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 patients 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 patients 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.

Clinical Implementation of a Head-Mounted Display of Patient Vital Signs

Head-mounted displays (HMDs) can superimpose a patients vital signs over the anesthesiologists field of view in the operating room. Prior simulator-based studies have found that anesthesiologists wearing an HMD spend more time looking towards the patient and less time looking towards the monitors compared to standard monitoring. We review potential approaches for interfacing an HMD with clinical monitoring equipment at the Royal Adelaide Hospital, and describe the technical solution we implemented. Furthermore, we implemented a method of recording video data in the operating room without interfering with normal clinical practice. Finally, we present analyses of two clinical scenarios where HMDs might be particularly useful.

Simulating capnography in software on the METI emergency care simulator.

Introduction: We attempted to adapt a METI Emergency Care Simulator to support anesthesia scenarios but faced two challenges: the CO2 gas exhaled by the mannequin does not represent the simulated patient’s physical status, and the METI Waveform Display software does not support capnography monitoring. Methods: We developed a software application that simulates a CO2 trace that corresponds to the mannequin’s ventilation. The software generated a range of CO2 waveform shapes whereas the mannequin was either spontaneously breathing or being mechanically ventilated. We tested the software in three environments: (1) a full-scale simulator research study of advanced anesthesia monitoring displays, (2) simulator-based training courses at the Royal Adelaide Hospital, and (3) at the Sydney Medical Simulation Centre. Results: The research study participants successfully used the simulated monitor to confirm correct intubation and detect airway events. Instructors at the Royal Adelaide Hospital reported improvement in the fidelity of simulations for anesthesia trainees. Simulation coordinators at the Sydney Medical Simulation Centre were able to use their Emergency Care Simulator for anesthesia training scenarios, which they were previously unable to run. Conclusion: We were able to substantially increase the realism of our anesthetic scenarios for research studies and training participants with only a small increase in the fidelity of our capnography monitoring.

Summative evaluation with a full-scale patient simulator: Challenges and adaptations

In this paper we outline considerations that went into designing and executing a full-scale simulator-based summative evaluation of four different display configurations for presenting information about anesthetized patients to an anesthesiologist. Although patient simulators appear to provide a “natural laboratory” for evaluating medical device innovations and equipment interface concepts, the software underlying patient simulators can be unequal to the challenges posed by the need for good representation of patient physiology and good experimental control. Moreover, the opportunities that full-scale patient simulators can offer for completely interactive, event-driven scenarios can present problems for experimental control and can promote participant hypervigilance. We describe the design of our experimental scenarios, the challenges our scenarios posed for simulator software and how we overcame those challenges, the design of a distractor task, and the methodology used to ensure we collected behavioral data sensitive to the manipulations of interest. Our adaptations in the face of challenges posed by the full-scale simulator context let us design an experiment that was highly informative about the advantages and disadvantages of the display configurations of interest.