2016 Section 5 Green Book

number of minimally invasive surgical techniques.

3,13–17

Despite advances in software, computer processing speeds,

and registration algorithms, very few of these systems

appear to be used during routine procedures. Poor adoption

of computer-based assistance through advanced displays

has been noted in many industries where technical preci-

sion is required.

18,19

Although there is huge potential for

this technology, functional deployment has been restricted

by limited human factors research investigating interface

design.

It was a significant undertaking to create a mock

OR with a full set of skull base equipment and recruit

experienced skull base surgeons for a 5-hour trial. We

wished to make the setting, the procedure, and the sub-

jects (end users) as close to reality as possible to obtain

the feedback required to make the system changes nec-

essary for integration into the OR. We gained valuable

insight into how different surgeons used the system and

noted many similar themes as well as individual differ-

ences. Such observations are useful in adapting feedback

to be as functional as possible while allowing customiza-

tion where requested.

The mental demand, effort, and frustration levels

were shown to be significantly decreased when using the

LIVE-IGS system. All surgeons also appreciated that the

overall stress level was much lower operating on a cadaver

than a live patient. Drilling adjacent to the carotid or

toward the dura in a real operation would be significantly

more stressful, and the workload differences may be even

greater in a real situation. Subjects commented that it was

less demanding to drill when they were some distance

(e.g., around 5 mm) away from a critical structure and

could quickly check their anatomical position and continue

to ablate with confidence. They noted that if they were

using traditional style intermittent IGS, or a Doppler

probe, they would have checked less frequently, due to the

time and interruption required to switch to a different

probe, thereby continuing with ablation in a slower and

more cautious fashion. We believe that the lower task

workload scores reflect this level of reassurance offered by

the technology. Incorporating testing of mental workload

with tools such as the NASA-TLX has been recommended

by other authors, given that traditional outcome parame-

ters such as morbidity and mortality are practically impos-

sible to quantify in this style of translational research.

Inferior task performance and a greater number of errors

have been noted when mental workload is increased.

When providing a 3D virtual view of anatomical

contours, a reference framework must be included to

allow surgeons to conceptualize how they relate to the

real-life anatomy they are viewing. A mesh surface ren-

dering was presented to place the contours in context.

We had mixed reviews on the virtual display, particu-

larly in regard to the mesh. Some wanted less mesh,

some wanted a more realistic surface rendering, and

others did not use it or found it confusing. There was

certainly no consensus on the best way to display 3D

contours, and given this we believe allowing customized

display settings incorporating various virtual views with

adjustable opacity as well as fused augmented reality

views may be appropriate.

The integration of live visual displays and auditory

alerts involves additional stimuli that inherently

demand some attention. Strategies to mitigate unneces-

sary distraction are important in human–computer

interface design.

22–24

Like some other groups, we placed

all of the visual augmentation on the submonitor to

avoid direct visual stimulation at critical points.

3,25

This

design led to most surgeons referencing this data at

their discretion rather than forcing their attention

through on-screen visual cues. When abstract sound

alerts were used as proximity alerts, we noted the sur-

geon would often scan the submonitor to see why it was

alerting. Auditory icons were developed and replaced

abstract sounds for the proximity alerts after the first

three subjects suggested that individual identification of

structures would be preferable. Auditory icons are

alarms that bear some relationship to their function and

are easily learnt.

For the carotid artery, we created an

alarm reminiscent of an arterial Doppler trace for the

proximity zone and added a beep at the end when the

instrument was tracked to be within, or extremely close

to, the carotid volume. This was almost instantly recog-

nizable and learnt by surgeons and provided informative

feedback on the reason for alarm without disrupting dis-

section. It was observed that the addition of this feature

was associated with decreased scanning of the submoni-

tor, and subjects reported being better informed and less

distracted. Driving simulation studies have shown simi-

lar results with visual distractions causing more erratic

steering than auditory distractions.

Sonification, turn-

ing data into sound (such as the change in tone with

pulse oximetry), can inform without the need to scan for

visual data. Investigation in anesthesia simulation

showed sonification allowed greater time-sharing per-

formance between a manual and monitoring tasks when

compared to visual monitoring.

Although auditory icons

and sonification show great promise in limiting distrac-

tion, the plethora of other alarms and auditory stimuli

in the operating environment must be taken into

account.

This trial has provided our research group with a

better understanding of the issues limiting clinical

implementation of this technology as well as the poten-

tial clinical uses. We feel that reporting the preclinical

development of our system is important to promote effi-

cient progress toward improved surgeon–computer inter-

face design. Although registration accuracy and

robustness will always be a concern, this does not

appear to be a significant factor restricting adoption,

especially within the relatively rigid framework of the

skull base. The main barriers appear to relate to inter-

face design and the lack of integration of the elements

required to produce the features described. Streamlining

the system into a single package that allows intuitive

contouring, rapid registration and instrument calibra-

tion, and the ability to customize visual display and

alarm settings could make this technology only margin-

ally more complex to set up than current IGS systems.

We are unsure whether the cost and time required to

provide this information would make it suitable for more

routine cases such as endoscopic sinus surgery. Further

Laryngoscope 124: April 2014

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173