Surgical simulation and training for ENT surgery






  • Contents



  • Surgical simulation: gadget, teaching tool, or surgical strategy aid? 220



  • Simulation in endoscopic endonasal surgery: review and perspectives 222




Surgical simulation: gadget, teaching tool, or surgical strategy aid?



S.J. Daniel

Introduction


Many people wonder whether surgical simulation really is just a gadget: some think it is an important educational tool, while others see it as an aid to surgical strategy. There is, in fact, sufficient hard evidence to show that simulation improves knowledge and skill acquisition, although this obviously means that the simulation has to target the knowledge or skill in question.


Why bother about simulation?


Technological and social changes over the last two decades have revolutionized the traditional “see one, do one, teach one” model of surgical training. In Canada, factors that have had direct impact on surgery-room teaching include the following:




  • regulations on residents’ working hours, to ensure patient safety and residents’ well-being [ , ]. The shortened working week has impacted patient care and medical teaching. The risk is that graduates may end up lacking certain skills that are essential to their specialty. For example, ENT specialists may not be at ease performing emergency cricothyroidectomy if they have never encountered the procedure during training;



  • a culture of responsibility, with an expectation on the part of society that the population’s needs should be met, with quality standards and particular attention to patient safety. What kind of parent would happily agree to their child being the guinea-pig for a junior trainee trying out his or her first mastoid surgery?



  • the development of new technologies and procedures, some of which come with a long learning-curve: robotic surgery, sialendoscopy, middle-ear endoscopic surgery, skull base surgery.



Simulation provides an interesting response to these three challenges that have catalyzed change in our training system. It is also an important tool in the revolution that the Royal College of Physicians and Surgeons of Canada set off in the medical education system, with the “competence by design” approach whereby medical training throughout the country is founded on “competences” to be included in the training and assessment of residents and physicians. This model, supporting continuous training and skill enhancement, is structured around competence and productivity rather than on duration of training alone.


Simulation is an excellent means of ensuring patient safety, while allowing trainees to learn from their mistakes in mastering skills and achieving excellence in surgical techniques and procedures. Graber et al. demonstrated that patients were more likely to agree to be operated on by a trainee who has acquired the appropriate skill on simulation [ ].


Traditional surgical simulation


Many simulations of surgical techniques are carried out on human cadavers or animal models. Examples from McGill University include temporal bone dissection laboratories, human cadaver sinus and skull base endoscopic surgery laboratories, head and neck dissection workshops on cadavers embalmed by a method that conserves tissue texture, airway reconstruction and foreign-body ablation workshops in anesthetized pig, and cochlea ablation in chinchilla. The advantages of such models include anatomic precision, tissue quality and tactile and haptic feedback. A recent review of temporal bone dissection simulation platforms reported that cadaver dissection was the optimal teaching platform for this procedure [ ].


For reasons of access, cost and logistics, certain workshops now use 3D-printed models of the temporal bone, which provide almost comparable experience.


“Low-fidelity” models


These models are inexpensive and portable, with the advantage for the trainee of being able to progress by repetition and for the surgeon of being able to acquire psychomotor skills.


One of our simulation research projects compared residents’ performance and skill after learning by observation and assisting in the operating room versus structured learning on a simple model comprising a small metal box with a latex membrane, in which tube insertion under microscopic control could be practiced: the simulation group performed better in terms of speed, ergonomy, precision and tissue preservation.


Integrating virtual reality simulation in clinical practice


It will revolutionize training for the upcoming generation. It provides immediate feedback and often includes objective assessment measurements such as time and motion analysis. One disadvantage is cost, which can be exorbitant. A recent meta-analysis by Nagendran et al. demonstrated the interest of integrating virtual reality simulation in surgical training programs [ ].


Advantages of surgery simulation


As well as giving the trainee plenteous opportunity to practice a skill or procedure, simulation provides immediate feedback in a safe setting. In a randomized study, Moulton et al. showed that residents maintained skills acquired by simulation better when practice was spread out rather than concentrated, for example in a single day [ ].


Several studies reported improved surgical performance and reduced complications rates with simulation [ , ]. Simulation also allows preparation for a given procedure or clinical situation, and can compensate for lack of turnover for certain clinical procedures.


Simulation can also serve as a proxy, for objective assessment of residents’ and physicians’ surgical skills. For example, the Quebec College of Physicians requires anesthetists at the end of their career to take a structured examination in a simulation center.


Simulation can also be used to assess mastery beyond the question of procedural skill: e.g. the surgeon’s communication skills, interaction with the rest of the team, speed of decision-making, and clinical reasoning in front of particular situations.


Limitations


Some surgeons have lingering doubts as to how skills acquired in simulation are transferred to the actual operating room, although this has in fact been the focus of several studies [ ]. Others speak of skill decontextualization in simulation.


Research


Simulation can also be useful in advanced research programs: e.g. finite elements analysis enabled realistic simulation of neonate middle-ear acoustic input admittance. This is useful for developing auditory screening technologies [ ].


Conclusion


Surgical simulation is a precious educational tool that enhances trainees’ acquisition of skills and knowledge. As medical teaching worldwide progresses toward a skill-based system, simulation is destined to become increasingly important in training, in parallel to clinical practice, and in physician assessment.


Future studies should focus on the transferability of skills acquired in simulation to the operating room. Stress should also be placed on the full range of technical skills and aptitudes such as team-work, communication, professionalism and leadership.




Simulation in endoscopic endonasal surgery: review and perspectives



C. Rumeau
J. Rebois
P. Gallet

Introduction


Endoscopic surgery places an interface between the surgeon and the operative field, entailing extra difficulties in training. Bakker et al. [ ] reported that hand-eye coordination, 3D location (particularly when using an angled objective) and recognition of surgical landmarks (correspondence between operative view and imaging) were considered by both trainees and experts to be the most difficult skills to acquire in endoscopic surgery. It is thus unsurprising that the procedures for which simulation has been most studied are those involving optical guidance, such as laparoscopic or robotic-assisted surgery, where prior mastery of the equipment and of endoscopic visualization is necessary.


The benefits expected from basic training by simulation in endoscopic endonasal surgery are multiple. The first is obvious: operating position and camera manipulation [ ] cannot be acquired by a trainee working purely as a surgical assistant. The same is true for the mental gymnastics of transposing the 2D screen view onto a three-dimensional cavity, which can be achieved by the operator consciously positioning the camera and/or instruments. Finally, prior mastery of basic actions, such as opening and closing Blakesley forceps or manipulating an aspiration drain or raspatory, can only improve efficiency in theater. A surgeon who has mastered the non-specific actions will better be able to concentrate on the particularities of patient and pathology [ , ].


Applying Fitts and Posner’s theory [ ] to medical practice, task learning comprises three stages:




  • cognitive: i.e. understanding the mechanisms;



  • associative: thanks to practice and the supervisors’ comments, the trainee acquires the appropriate motor behavior; he or she may still have to think about what they are doing, but it becomes increasingly fluid;



  • autonomous: the action is fluid and automatic and the learner can concentrate on the other aspects of the procedure and take full advantage of the specific advice that the senior or tutor can provide. A student who has mastered the fundamental procedures outside of theater will learn more in the actual operating room than if he or she has to be concentrating on basics.



However, the development of simulation is rather recent in the ENT sphere. This chapter will try to present an overview of existing tools and perspectives for progress in endoscopic endonasal surgery simulation.


Review of simulation supports


Two types of tool are currently available: physical supports, and virtual reality platforms.


Physical supports


Physical supports dedicated to surgery training can be more or less faithful to anatomic reality: i.e. “high-fidelity” and “low-fidelity”.


High-fidelity supports


Cadaver dissection


This method of learning is certainly the oldest kind of surgical simulation, with incomparable realism, both anatomic and physical (force feedback). Laboratory access, however, is not always easy, cadaver availability is limited, costs are high, and tissue conservation is not always optimal. Moreover, these supports are by definition of variable anatomy, hindering standardized evaluation.


Animal dissection


To compensate for the dearth of human specimens, animal models have been proposed. The most widely studied animal in endonasal surgery is the sheep [ ], as the nasal cavities are of easy access, with a size relatively well suited for the usual instruments of human surgery. One advantage of animal models is the possibility of practicing on live anesthetized animals, if an adapted structure is available, thus closely reproducing real surgical conditions, including bleeding [ , ].


However, despite physical realism, the anatomic realism is debatable and anatomy is variable, hindering standardized evaluation.


Artificial supports


The theoretic advantage of artificial supports is to enable learning on reproducible models; Physical realism, on the other hand, is harder to ensure. The most widely used model in France is currently the Phacon® model (Leipzig), which can be connected up to a CT-guided navigator [ ].


Low-fidelity supports


The development of endoscopic surgery simulators for neurosurgical and rhinoneurosurgical applications is currently making great strides. Interest is focusing on the central fossa of the skull base (sphenoid and surrounding region), with the aim of improving training in endonasal drilling and the surgical anatomy of the sella turcica. For the ethmoid, only the principal bony septa are concerned, for drilling rather than dissection [ ].


We shall mention here two low-fidelity simulators for endoscopic endonasal surgery: the EggHead [ ] and the Low-Cost Task Trainer [ , ].


The EggHead [ ] is a training simulator for endoscopic approaches to the pituitary gland, in which the sella turcica is represented by a hard-boiled hen’s egg, with the yolk representing a pituitary adenoma. The idea is to reach the yolk by dissecting the shell (sella turcica) and creating a corridor through the egg-white, sparing the egg-white laterally bounding the yolk, which represents the pituitary environment (internal carotids and cavernous sinuses). EggHead can be reutilized without limit.


The Low-Cost Task Trainer [ ] is a jelly mold with a central cavity bordered by two hard-boiled eggs representing the maxillary sinuses. Holes in the superior side of the cavity represent access to the frontal sinuses (frontonasal ducts), with full-thickness sutures to be grasped with forceps, and colored marks representing targets for saline injection. The whole thing is covered with a silicone face mask to focus on the working area (nasal cavities).


Virtual reality


A 2014 review of the literature by Arora et al. [ ] retrieved 21 articles testing 8 head and neck surgery virtual reality platforms, including 2 (4 articles) dedicated to endoscopic endonasal surgery. They used haptic commands to control the objective and the surgical instruments. Construct validity (ability to differentiate experts from novices) was assessed in only 6 of the 21 studies, with results in favor of one of the endonasal simulation platforms [ ]. Subsequently, a third platform, the McGill Simulator for Endoscopic Sinus Surgery (MSESS), showed good construct validity [ ]. Performance on the endoscopic sinus surgery (ES3) simulator seemed to be predictive of surgical performance [ ]. Thawani et al. [ ] reported that, after 6 months’ training on a haptic command simulator, real-life performance in endoscopic sphenoidotomy was significantly better than after classical training.


However, it is not clear that the virtual image gives good contrast in soft tissues; thus it may not provide satisfactory training in detecting the right dissection plane [ , ]. The cost of developing (and hence purchasing) such platforms is high, which restricts widespread use. Moreover, the predefined scenarios do not allow the great variety of endonasal surgical instruments to all be tried out.


Cyrano


The Cyrano 1


1 Simulator developed by the authors with support from the Nancy School of Surgery, University of Lorraine, France.

simulator combines a physical support and a virtual interface. It comprises a realistic head support with 3D movement and a receptacle for flexible modules, equipped according to the exercise to be undertaken: targets, hooks, realistic anatomic support, etc. ( Figure 13.1 ).
Jun 9, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Surgical simulation and training for ENT surgery
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