Hierarchical Decomposition of Minimally Invasive Surgery:
A Valuable Research and Investigative Tool
MacKenzie, C.L., Ibbotson, J.A., Cao, C.G.L. & Lomax, A.J., Simon Fraser University, Canada
Where is the surgeon looking?
Analysis of gaze patterns: on the monitor, down on hands, away
What surgical steps are difficult and take time?
Note the time to wrap fundus is shortened when the short gastrics are cut
Duration of Fundoplication Surgical Steps
Duration (minutes)
No Division
40
35
30
25
20
15
10
5
0
Divide Short Gastrics
prepare patient
divide
peritoneum
expose crura
and EG junction
repair crura
divide short
gastrics
wrap fundus
S urgical S tep
What motions are performed most often during suturing?
Reaching and orienting
Frequency
Total Number of Motions for Suturing (both tools)
18
16
14
12
10
8
6
4
2
0
normal suture
4. Results
anchor suture
reach & orient
grasp & hold/cut
push
pull
Reach and
orient
Slip
grasper
under
release
Lift
Switch tool
Grasp
fundus
Transfer
grasp
Grasp and
hold / cut
Pull across
Insert
endostitch
Push
Suture
Pull
Knot
Release
Cut suture
Suture
Knot
Cut suture
Motion
Locate
Prepare patient
Divide
Locate
Divide
Locate
Expose crura and
GE junction
Divide peritoneum
Join
Locate
Repair crura
Divide
Elevate Pull fundus
esophagus
under
Divide short gastrics
Anchor
fundus
Suture
wrap
Wrap fundus
Close
Nissen
Fundoplication
1. Background
5. Discussion
 Complex activities break down to progressively smaller units
Hierarchical decomposition can be used to:
1. Evaluate surgeons’ performance
(Miller, Galanter & Pribram, 1960)
 Human factors, task analysis, user-task-tool
2. Design training for surgery e.g., with augmented or virtual environments
Modular sections correspond to our procedural breakdown
2. Purpose
3. Evaluate surgeons’ learning
1. To study the surgeon as the user of the technology in a complex
human-machine system
4. Design and evaluate effectiveness of new tools
5. Evaluate different aspects of O.R. layout e.g., monitor display position
2. To decompose minimally invasive surgery hierarchically
6. Preoperative planning of patient-specific surgery
3. Method
7. Analyze surgeons’ focus of attention at different levels of the hierarchy
8. Improve safety and decrease errors
 Videotape laparoscopic procedures:
- cholecystectomies
9. Make a better “fit” between technology and the surgeon.
(n = 4)
- inguinal hernia repairs (n = 4)
- Nissen fundoplications (n = 9)
 Define events e.g., tool entries, gaze shift, goal attainment
 Develop hierarchical decomposition
 Operationally define beginnings and endings of:
- surgical steps
- substeps
- tasks
- subtasks
- tool motions
 Annotate videotapes and perform analyses on the timing of events.
6. References
Cao, C.G.L., MacKenzie, C.L., Ibbotson, J.A., Turner, L.J., Blair, N.P. and Nagy, A.G. (1999).
Hierarchical decomposition of laparoscopic procedures. In Westwood, J.D., Hoffman,
H.M., Robb, R.A., & Stredney, D. (Eds.), The convergence of physical and informational
technologies: Options for a new era in healthcare. (MMVR: 7). Amsterdam: IOS Press, 8389.
Ibbotson, J.A., MacKenzie, C.L., Cao, C.G.L., and Lomax, A.J. (1999). Gaze patterns in
laparoscopic surgery. In Westwood, J.D., et al. (Eds.) The convergence of physical and
informational technologies: Options for a new era in healthcare. (MMVR: 7). Amsterdam:
IOS Press, 154-160.
MacKenzie, C.L., Ibbotson, J.A., Cao, C.G.L. and Lomax, A.J. (1998). Intelligent tools for
minimally invasive surgery: Safety and error issues. In Proceedings of Enhancing patient
safety and reducing errors in health care. Chicago: National Patient Safety Foundation,
226-229.
Miller, G.A., Galanter, E., and Pribram, K.H. (1960). Plans and the structure of behavior. New
York: Henry Holt and Co.
Acknowledgements
Thanks to the surgeons, O.R. staff, and patients. Thanks to E. Lee, S. Manske, and B. Zheng.
Funded by British Columbia Health Research Foundation (BCHRF) and Institute for Robotics and Intelligent Systems (IRIS), Canada.