Monitoring in anesthesia with head-mounted displays

David Liu (2010). Monitoring in anesthesia with head-mounted displays PhD Thesis, School of Information Technol and Elec Engineering, The University of Queensland.

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Author David Liu
Thesis Title Monitoring in anesthesia with head-mounted displays
School, Centre or Institute School of Information Technol and Elec Engineering
Institution The University of Queensland
Publication date 2010-06
Thesis type PhD Thesis
Supervisor Prof Penelope M Sanderson
A/Prof Marcus O Watson
Prof W John Russell
Total pages 120
Total colour pages 29
Total black and white pages 91
Subjects 08 Information and Computing Sciences
Abstract/Summary Anesthesiologists monitor their patients' vital signs vigilantly during surgical procedures in the operating room. The vital signs are typically presented on a graphical display mounted on the anesthesia workstation, but the display is often located in an awkward position and out of view of the anesthesiologist, especially when they are performing procedures. One solution to this problem is the use of head-mounted displays. Head-mounted displays (HMDs) are head-worn display devices that project a computer-generated information display over the user's field of view, similar to the head-up displays commonly used in aviation. Anesthesiologists using an HMD would be able to see the vital signs at all times in the operating room – no matter where they are, or where they are looking. Despite their technological and methodological limitations, prior investigations of HMDs in anesthesia have demonstrated benefits such as improved event detection and a reduced need to look towards the anesthesia workstation. In other domains, however, researchers have found cognitive and perceptual issues associated with the use of head-up displays that have not been investigated with HMDs in anesthesia. Head-up displays can worsen the tendency for users to miss salient, safety-critical unexpected events in their visual field (the sustained inattentional blindness phenomenon), and this has been replicated with HMDs in laboratory settings. Head-up displays can also cause perceptual problems such as involuntary eye mis-accommodation, resulting in decreased visual acuity and slower event detection. This thesis reports a series of three experiments that was conducted to determine whether the advantages and disadvantages of head-up displays in aviation would also apply to HMDs in anesthesia. Anesthesiologists at the Royal Adelaide Hospital provided anesthesia in simulated and clinical operating room environments while using either a standard patient monitoring display, or the standard display plus a Microvision Nomad ND2000 HMD. The HMD presented a real-time display of the patient's vital signs that was visible to the anesthesiologist at all times. All of the simulator scenarios and surgical cases were video recorded for offline coding and analysis. In Experiment 1, twelve anesthesiologists provided anesthesia in a simulated operating room environment using a METI Emergency Care Simulator. The goals of the study were to determine (1) whether HMDs would help anesthesiologists detect unexpected events faster during normal anesthesia, and (2) whether the HMD focal depth would affect their performance. The results showed that there was no significant difference in the number of events detected, nor event detection times, between the display conditions and focal depths. When using the HMD, however, participants spent a smaller proportion of time looking towards the anesthesia workstation, and a greater proportion of time looking towards the patient and surgical field. In Experiment 2, twelve anesthesiologists performed a simulated prolonged fiber-optic intubation by navigating a Replicant Dexter Endoscopic Dexterity Trainer maze using a fiber-optic scope while monitoring patient vital signs. The goal of the study was to determine whether HMDs would help anesthesiologists detect patient events faster when they are physical and operationally constrained. The results showed that participants detected two of four events faster when using the HMD compared to standard monitoring, but another waveform event was detected more slowly with the HMD. The slower event detection could not be explained by inattentional blindness alone, but by a combination of inattentional blindness, perceptual differences between events, and overconfidence. In conditions with the HMD, participants again spent less time looking towards the workstation and more time looking towards the patient area, as in Experiment 1. In Experiment 3, six anesthesiologists provided anesthesia for human patients undergoing elective rigid cystoscopy surgical procedures. The goal of the study was to determine whether the reduced need for anesthesiologists using HMDs to look at the monitors would translate from the simulated operating rooms in Experiments 1 and 2 to the clinical environment. The results showed that in conditions with the HMD, participants spent less time looking towards the workstation, and more towards the patient and surgical field, as in the prior experiments. The findings from the three experiments confirm that HMDs can help anesthesiologists redirect their attention away from the anesthesia workstation and towards the patient and surgical field. However, the benefits of monitoring with HMDs were more pronounced during constrained contexts, where the anesthesiologist could also detect patient events more quickly with the HMD, than during routine monitoring. Although there was no direct evidence of inattentional blindness (as per the aviation studies of head-up displays), improved display design techniques may be required to mitigate the slower detection of waveform changes on the HMD. The technologies needed to conduct the above experiments were not commercially available therefore several innovative solutions were developed. A wireless HMD monitoring system was built using off-the-shelf components and interfaced with a patient simulator (Experiments 1 and 2) and clinical patient monitors (Experiment 3) to display patient vital signs in real-time. The simulator was extended to provide capnography, airway gas monitoring, and blood pressure cycling. Finally, an audiovisual recording system was developed to record video data in the operating room, and a custom software tool was written for coding the video data. In future work, more research is needed to investigate the benefits that HMDs can provide during specific situations, such as crisis management or providing anesthesia to unstable patients; designing effective information displays for HMDs; and integrating the HMD with other display modalities such as auditory and vibrotactile displays.
Keyword anesthesia
clinical trial
head-mounted display
head-up display
human factors
inattentional blindness
medical simulation
operating room
patient monitoring
vital signs
Additional Notes Colour pages: 1, 24, 26, 29, 32, 34, 36, 41, 45-47, 74, 77, 79-81, 90-96, 98-103

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Created: Tue, 12 Oct 2010, 13:25:52 EST by Mr David Liu on behalf of Library - Information Access Service