What is Surgical Simulation?

Various types of simulators have been effectively used at all levels of surgical education from medical undergraduates, residents, fully trained surgeons in many specialties seeking continuing education, and even to educate the general public about the work of surgeons and what really happens "behind the scenes" in the operating room, emergency room, or intensive care unit. Most surgical simulation systems for simulation of actual performance are based in virtual reality. Thus, an ideal simulation system for this application has:

1. Segmentation (the anatomic workspace);
2. Tissue modeling (the material properties of the individual organs actually feel like the organ);
3. Tissue-tool interactions (the surgeon can manipulate the organs/tissues with instruments to recreate the kinds of interactions and collisions that occur during surgery);
4. Haptics (the feel of the system and the feedback of the system to the operator; both related to the tissue modeling and tissue-tool interactions);
5. Visual feedback has real color, shapes, bleeding, suture appearance, etc;
6. Real-time system integration (so that "suspension of disbelief" occurs);
7. Physiology is presented and errors can occur so that learning ensues.

Critique of Surgical Simulation Studies

Derossis and colleagues demonstrated face and content validity for a laparoscopic surgical simulator using surgical residents and fully trained surgeons as overall skill prediction could be predicted by level of training and frequency of repetition of the skill.[1] In their subsequent study they noted that improvements in performance of trainee surgical residents using the simulator could be demonstrated.[2]

Fried and colleagues recently provided important data on the validity of the McGill Inanimate System for Training and Evaluation of Laparoscopic Skills (MISTELS), a physical laparoscopic simulator.[3] The simulator teaches transfer, cutting, ligating loop, intracoroporeal and extracorporeal suturing skills. Each exercise is scored for efficiency (time) and precision (penalty) A cutoff time is assigned for each task. The time score (efficiency is calculated by subtracting the actual time from the cutoff time and a penalty score is applied for errors or lack of precision. The penalty score is subtracted from the efficiency score to give a final score. A target score was determined by reviewing results of raw scores for a group of excellent chief residents and fellows (unclear how these were chosen). The individual scores were normalized by dividing them by the target score to create an equivalent range of scores. Construct validity was demonstrated by differences in scores for each task and total score for junior residents, intermediate residents PGY 3-4 and senior (fellows, PGY5, practicing surgeons). Likewise, concurrent/predictive validity was shown by a linear regression of 0.81.

References

1. Derossis AM, Fried GM, Abrahamovicz M et al: Development of a model for training and evaluation of laparoscopic skills. Am J Surg 1998; 175:482-487.
2. Derossis AM, Bothwell J, Sigman HH, Fried GM: The effect of practice on performance in a laparoscopic simulator. Surg Endo 1998; 12:1117-1120.
3. Fried GM, Feldman LS, Vassilou MC et al: Proving the value of simulation in laparoscopic surgery. Ann Surg 2004; 240:518-528.