Minimally Invasive Surgery Task Decomposition -

Etymology of Endoscopic Suturing

Jacob Rosen* Ph.D.,

Lily Chang** MD, Jeff Brown ***, Andy Isch** MD

Blake Hannaford* Ph.D., Mika Sinanan** MD Ph.D., Richard Satava** MD

* Department of Electrical Engineering

** Department of Surgery

*** Department of Bioengineering

University of Washington

Seattle, Washington

Surgery - The Big Picture

Surgeon

Virtual Reality

Tool Tissue

Reality

Robot(master-slave)

HapticDevice TissueTool

Human - Machine Interface

Evaluation of Surgical Skill

Surgery - The Hidden Language Metaphor

Surgeon

HMI

Resident

Robot / Tool

Target Patient

Tool

Operator

LanguageLanguage

Surgery - The Hidden Language Elements

Human Language Surgical Language Markov Model

Book Operation Multiple Models

Chapter Step of the Operation Single Model

Words Tool/Tissue Interaction State

Pronunciation Force / Torque Observation

Research Aim

Create new quantitative knowledge of the forces and torques (F/T) applied by surgeons to their instruments and the positions and orientations (P/O) of the endoscopic tools during minimally invasive surgery

Develop and evaluate an objective surgical skill scale based multi finite state models (Markov Model) incorporating information regarding the kinematics and the dynamics of the endoscopic tools

Instrumented Endoscopic Grasper

Blue DRAGON

Blue DRAGON

Blue DRAGON - Graphical User Interface

Experimental System

PC (A/D)

VCR(PIP Mode)

Video

Blue DRAGONLeft

Contact

R

FMMMFFF

gzyx

gzyxzyx

,,,,

,,,,,,

Blue DRAGONRight

Endoscope

GUI

Mixer

Data

13 (Channels) * 2 (Dragons) = 26 Channels

Experimental Protocol

Surgical Tasks:

Task 1: Running the bowel, 10x3” (right to left) Task 2: Running the bowel, 10x3” (left to right) Task 3: Dissecting Mesenteric Vessels, 4x Task 4: Passing a Suture, 5x Task 5: Tying a Knot, 4x Task 6: Suturing the Bowel and Tying a Knot Task 7: Passing Stomach Fundus behind the Esophagus, 1x

Subjects: 5x (R1, R2, R3, R4, R5, E) - 30 Subjects

Normalized Completion TimeLearning Curve of Surgical Residents

1.00

1.96

3.87

4.59

3.69

7.08

0

1

2

3

4

5

6

7

8

9

10

R1 R2 R3 R4 R5 E

Training Level

Nor

mal

ized

Com

plet

ion

Tim

e

Novice

Expert

Position (Path) - Raw Data

Normalized Trajectory LengthLearning Curve of Surgical Residents

1.00

1.94

2.81

3.46

2.46

5.58

0

1

2

3

4

5

6

7

8

9

10

R1 R2 R3 R4 R5 E

Training Level

Nor

mal

ized

Too

l Tip

s P

ath

Leng

th (

Left

& R

ight

)

Novice

Expert

Forces - Raw Data

Novice

Expert

Torques - Raw Data

Tool/Tissue-Object Interactions - Taxonomy

-200

-150

-100

-50

0

50

100

150

200Fxy [N]

Fz [N]

Fg [N]

Txy [Nm] x10E2

Tz [Nm] x10E2Wxy [r/s] x10E3

Wz [r/s] x10E3

Vz [m/s] x10E5

Wg [r/s] x10E4

F/T Clusters (GR-PS-SW)

Generalized Markov Model of MIS Surgery - One Tool

GR

ID

PS-SW-SP

GR-PS-SW

GR-PL-SW

SW-SP

PS-SW

PS-SP

GR-SW

GR-PS

GR-PL

SW

PS

SP

Generalized Markov Model of MIS Surgery - Two Tools

Right ToolLeft Tool1 R

2 R

3 R

4 R

5 R

6 R

8 R

9 R

10 R

11 R

12 R

13 R

14 R

15 R15 L

14 L

13 L

12 L

11 L

10 L

9 L

8 L

7 L

6 L

5 L

4 L

3 L

2 L

1 L

7 R

Laparoscopic CholecystectomyExposure of Cystic Duct

SurgeonNon - Surgeon

GR

ID

PS-SW-SP

GR-PS-SW

GR-PL-SW

SW-SP

PS-SW

PS-SP

GR-SW

GR-PS

GR-PL

SW

PS

1 R

2 R

3 R

4 R

5 R

6 R

8 R

9 R

10 R

11 R

12 R

13 R

14 R

15 R15 L

14 L

13 L

12 L

11 L

10 L

9 L

8 L

7 L

6 L

5 L

4 L

3 L

2 L

1 L

7 R

Learning Curve - Markov Model Statistical Distance

R1 R2

R3

R4

R5

E

Normalized Statistical DistanceLearning Curve of Surgical Residents

1.0000

1.9972

5.07734.5722

3.8967

8.3436

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

R1 R2 R3 R4 R5 E

Training Level

Nor

mal

ized

Sta

tistic

al D

ista

nce

(Mar

kov

Mod

els)

Subjective Score (Video Analysis) - CriteriaSuturing the Bowel and Tying a Knot

Overall performance [1-5] Economy of movement [1-5] Tissue handling [1-5] Numbers of errors [No.]

– Drop needle– Drop suture– Lose suture loop– Break suture– Needle injury to adjacent tissue– Inability to puncture bowel with needle

Normalized Subjective Score (Video Analysis)Learning Curve of Surgical Residents

34

60 60

75

86

100

0

20

40

60

80

100

R1 R2 R3 R4 R5 E

Training Level

Sub

ject

ive

Sco

re

Correlation Between Subjective and ObjectiveAssessment of Surgical Skill

R1 (34.4, 8.34)

R2 (59.6, 3.9)

R3 (60.0, 4.6)

R4 (74.7, 5.1)

R5 (86.5, 2.0)

E (100, 1)

R2 = 0.8623

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100

Subjective Analysis (Video Analysis)

Ob

ject

ive

An

alys

is (

Mar

kov

Mo

del

)

Conclusions / Application

Analyzing Minimally Invasive Surgery requires a synthesis between visual and haptic information.

Differences between expert and novice surgeons can be defined in terms of: – Force / Torque / Velocity signatures – State transitions / combinations– Time spent in each state– Trajectory (tool tip) length

Good correlation (R2=0.86) between objective (Markov Model) and subjective (video analysis scoring) assessment of surgical skill

The objective methodology for surgical skill evaluation is a modality independent. It can be applied to:– In-vivo surgical conditions– Telerobotic systems

– VR haptics simulators

10Q