Keywords

1 Introduction

Laparoscopic surgery has been developed from 1990s, rapidly. Compared with the conventional open operation, it is characterized to use video system during hand-eye co-ordination, and thought to be more difficult to acquire the surgical technique [1].

Eye movement differences between novices and experts have been shown in the various fields, such as pilots and radiologists [2, 3]. Thus, the domain knowledge and experience affect the performance and eye movement on the related task. So far, a few papers compared the eye gaze movement behavior of novice and expert surgeons during performance of a laparoscopic surgery task with a simulator. Here we describe the hand motion and eye movement analysis during operation of laparoscopic cholecystectomy on simulator

2 Method

The examinee operated the same case of the laparoscopic cholecystectomy of the simulator, LapVR, according to the guidance of the software. The eye movement was measured by TalkEyeII (Takei Scientific Instruments) and EMR ACTUS (nac Image Technology Inc.). The eye movement detection method was a pupil corneal reflection method, and the detection rate was 60 Hz. The surgery contents were devided into 5 parts; dissection of the triangle of Calot and identification of the cystic duct and the cystic artery (step 1), clipping and cut of the cystic duct (step 2), clipping and cut of the cystic artery (step 3), dissecting of the gallbladder away from the gallbladder bed (step 4), removing the specimen and irrigate the abdominal cavity, if necessary (step 5). The movement of the operator’s hands was analyzed from the video. The simulation was done in two settings, conducted by the solo operator and with a camera operator wearing the eye tracking glasses.

2.1 Experiment 1

The expert and novice surgeons operated cholecystectomy on the simulator with same scenario. Their eye movement was analyzed as described above. Also, their touch field of both hands were analyzed by the video.

2.2 Experiment 2

Four stuff surgeons demonstrated laparoscopic cholecystectomy using the simulator, and they explained their procedure at the same time. Twenty-three medical students did same scenario, and the stuff surgeon instructed them. The trainer’s talking was recorded with video, and analyzed its contents. The contents were categorized into four elements, procedure, how to use surgical instrument, how to use the simulator, and how to deal with intraoperative complication. The two factors, procedure and how to use the surgical instruments, were divided into several elements, such as, organs, surgical forceps, handling, and directions, and their combination.

3 Result

3.1 Experience 1

In step 1, the operative field is relatively narrow, and the right hand of the novices touched the triangle of Calot, and the left hand the neck of the gallbladder, mainly. Their left hand grasped and released the gallbladder, frequently (Fig. 1a). However, most of the period, their right hand touched nothing, because they encountered the complication, such as bleeding (Fig. 1b). In step 2 and 3, the operator needs to change their right hand’s operative instrument at least 4 times (Fig. 1c). The novices gazed the tip of the forceps, when they insert it. In step 4, the operative field enlarged compared with step 1, 2, and 3. The novices gazed their right hand for longer time than gallbladder (Fig. 1d).

Fig. 1.
figure 1

The gaging pattern and the movement of left and right hand of stuff surgeon and novice surgeon. Novice’s left hand grasped and released the gallbladder, frequently (a). However, most of the period, their right hand touched nothing, because they encountered the complication, such as bleeding (b). In step 2 and 3, the operator needs to change their right hand’s operative instrument at least 4 times (c). The novices gazed the tip of the forceps, when they insert it. In step 4, the operative field enlarged compared with step 1, 2, and 3. The novices gazed their right hand for longer time than gallbladder (d).

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On the other hand, the expert surgeon gazed the triangle of Calot in step 1. They once grasped the gallbladder, their left hand did not release it (Fig. 1e). In step 2 and 3, the expert gazed the target organ such as cystic duct and cystic artery, not the tip of the surgical instrument they insert (Fig. 1f). In step 4, the expert looked right hand (forceps) and the grasped gallbladder one after another (Fig. 1g).

During the simulation of the novice surgeon as an operator, the gaging point of both novice and stuff surgeon as a scopist. The gaging point of stuff surgeon was then discretely, and its pattern was similar with that of the novice surgeon (Fig. 2). But the common gaging point were only 32%.

Fig. 2.
figure 2

Gaging pattern difference of operator and scopist in the same operation. The stuff surgeon’s eye movement pattern showed more frequently coming and going to each organ, as if novice surgeon as an operator. The stuff surgeon focused on surgical instrument more, when he acted as a scopist.

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However, the common gaging point was only 32%. The gaging point of stuff surgeon as an operator and a scopist was quite different, even in the same scenario (Fig. 3).

Fig. 3.
figure 3

Gaging pattern difference of stuff surgeon as as operator and a scopist. The stuff surgeon’s eye movement pattern as a scopist showed more frequently coming and going to each organ and surgical instruments, as if novice surgeon as an operator.

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3.2 Experience 2

In the step 2, the duration from insertion of the forceps to reaching to the target organ with right hand was analyzed. The average time in second time was 13.3 s and significantly shorter than that in first time, 22.4 s (p < 0.05, Fig. 4).

Fig. 4.
figure 4

The duration time of reaching the objective organs by the surgical instrument from insertion into the abdominal cavity. At 1st time, the time was 22.4 s in average, but reduced to 13.3 s, significantly (p < 0.05).

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Figure 5 shows the gaging pattern to organ, such as gallbladder, cystic duct, and cystic artery, and forceps. The stuff surgeon finished step 2 in a short time, and the gaging pattern were well organized. The gaging pattern of medical students were various. Medical student A gaged organ and forceps in longer time as stuff surgeon and the times that his gaging points come and go were more frequent. The gaging point of student B showed coming and going ceaselessly. Most students reduced their time in step 2, however its gaging pattern did not change (Fig. 6).

Fig. 5.
figure 5

Gaging pattern of the stuff surgeon, and two medical students in the step 2, clipping and cut of the cystic duct. Stuff surgeon’s eye movement was reduced, while the medical students’ were unified but frequent, or discretely and frequent.

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Fig. 6.
figure 6

Gaging pattern of the medical students during their operation on the simulator in 1st time and 2nd time. Organ contains gallbladder, bile duct, cystic duct, cystic artery, and liver. Forceps means various surgical instrument such as grasper, scissors, and dissector.

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The content of teaching was investigated from the video and the stuff surgeon explain his procedure more, but fewer in how to use surgical instrument and how to deal with complication, such as bleeding and bile leakage (Fig. 7).

Fig. 7.
figure 7

The contents of explanation during operation of the stuff surgeon himself and guidance during medical student’s operation.

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In detail, the stuff surgeon explained more about anatomy, but taught to medical students focusing on the direction and handling of organ movement (Fig. 8).

Fig. 8.
figure 8

Explanation details from the video during the stuff surgeon’s demonstration and instruction during the medical student’s procedure on the simulator. Stuff surgeon explained much about anatomy in their demonstration, but more focused in directions of organs or forceps.

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4 Discussion

In this study, differences of gaze behavior and hand movement in various level of surgeon were analyzed using laparoscopic surgery simulator. The expert operator showed economical hand and eye movement compared with novices. Once their act change to a camera operator, their gaze behavior seemed to change to the trainer’s one. However, its coherence was only 32% (Fig. 2). The expert surgeon (stuff surgeon) gaged to surgical instrument more, when they act as a scopist, suggesting that they made sure the operation had done safely.

From the analysis of medical students, the time of the surgical procedure were easily shortened in a short period, but the eye movement did not make more efficient at the same time. Eye movement development may more difficult to acquire than that of simple task in laparoscopic surgery. From these data, it is suggested that the gaging pattern may be a new indicator to show proficiency level of each surgeon.

When expert surgeon demonstrated their operation and guidance it at the same time, they focused more on the anatomy of cholecystectomy, not how to use the instrument, how to make operation field to move organs using forceps, and how to deal with intraoperative complication. In actual surgery, such information is more important, but a few surgical textbook and text videos show successful cases. Also, the content of teaching during operation were various in each medical student. From these points, the new educational system can be established to train the medical student, novice surgeon, and also expert surgeons as trainer.