Creation of a High Fidelity, Cost Effective, Real World Surgical Simulation for Surgical Education

Background How do surgical residents learn to operate? What is a surgical plane? How does one learn to see and dissect the plane? How do surgical residents learn tissue handling and suturing (sewing)? One method to learn and practice performing surgery is through the use of simulation training. Surgical training models include laparoscopic box trainers (a plastic box with holes for instruments) with synthetic materials inside to simulate tissues, or computer-based virtual reality simulation for laparoscopic, endoscopic, and robotic techniques. These methods, however, do not use real tissues. They lack the haptic and kinesthetic feedback of real tissue. These simulations fail to recreate the fidelity of soft tissues, do not foster the ability to accurately see surgical planes, do not accurately mimic the act of dissecting surgical planes, do not allow for complex surgical procedures, and do not provide accurate experience to learn tissue handling and suturing. Despite their poor performance, these plastic and virtual trainers are extremely costly to purchase, maintain, and keep up to date - with prices starting at $700 for basic plastic training boxes to thousands of dollars for virtual simulation. Also, there are additional costs of maintenance and software curriculum. Despite the cost of software, virtual simulators do not include a simulation for every surgery. Our aim was to create a life-like surgical simulation as close to real world as possible that allows trainees to learn how to see and dissect surgical planes, learn how soft tissues move, and learn the dynamics of soft tissue manipulation. We created a laparoscopic simulator using porcine tissues for gallbladder removal, acid reflux surgery, and surgery to treat swallowing difficulties (cholecystectomy, Nissen fundoplication, and Heller myotomy, respectively). Second year general surgery residents were able to practice these procedures on real tissues, enabling them to learn the steps of each procedure, increase manual dexterity, improve use of laparoscopic equipment, all while maintaining life-like haptic, soft-tissue feedback and enabling them to develop the ability to see real surgical planes. Methods The abdomen was recreated by purchasing intact porcine liver, gallbladder, (Cholecystectomy simulation) and intact esophagus, stomach, and diaphragm (Nissen and Heller simulation) from a packing supplier. Each organ system was placed into a laparoscopic trainer box with the ability to re-create laparoscopic ports. Surgical residents were then able to perform the procedures using real laparoscopic instruments, laparoscopic camera/video imaging, and real-time electrocautery. The simulation included all critical steps of each procedure such as obtaining the critical view of safety and removing the gallbladder from the liver bed (cholecystectomy), wrapping the stomach around the esophagus and laparoscopic suturing (Nissen fundoplication), and dissecting the muscular portion of the esophageal wall (Heller myotomy). Because these porcine tissues were readily available, several stations were set-up to teach multiple residents during each session (10-12 residents / session). Discussion Surgeons develop haptic perception of soft tissues by cutaneous or tactile feedback and kinesthetic feedback (Okamura, 2009). Kinesthetic feedback is the force and pressure transmitted by the soft tissues along the shaft of the laparoscopic instruments (Okamura, 2009). This soft tissue simulation re-creates the ability to experience what soft tissue feedback feels like, outside a normal operative environment. Real tissue learning allows trainees to learn how to see surgical planes, learn how soft tissues feel and move, develop proficiency in surgical dissection, and learn how to suture laparoscopically. This is the only model that recreates the movement of soft tissues and visualization of dissection planes outside the operative environment. Because this model utilizes the laparoscopic instruments used in the operating room, residents also develop familiarity with laparoscopic instruments, thus, flattening another learning curve. A literature review found that this is the only real tissue simulation being performed for foregut procedures used specifically for resident training. By building a realistic, anatomical model with inherent accurate soft tissue surgical planes, surgical trainees can have a more realistic surgical experience and develop skills in a safe, low pressure environment without sacrificing the hepatic learning and surgical visualization that is critical to performing safe laparoscopic surgery. All residents that participated in the stimulation reported positive feedback and felt that is contributed to their surgical education.

MALDI MSI Reveals the Spatial Distribution of Protein Markers in Tracheobronchial Lymph Nodes and Lung of Pigs after Respiratory Infection

Respiratory infections are a real threat for humans, and therefore the pig model is of interest for studies. As one of a case for studies, Actinobacillus pleuropneumoniae (APP) caused infections and still worries many pig breeders around the world. To better understand the influence of pathogenic effect of APP on a respiratory system—lungs and tracheobronchial lymph nodes (TBLN), we aimed to employ matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-TOF MSI). In this study, six pigs were intranasally infected by APP and two were used as non-infected control, and 48 cryosections have been obtained. MALDI-TOF MSI and immunohistochemistry (IHC) were used to study spatial distribution of infectious markers, especially interleukins, in cryosections of porcine tissues of lungs (necrotic area, marginal zone) and tracheobronchial lymph nodes (TBLN) from pigs infected by APP. CD163, interleukin 1β (IL-1β) and a protegrin-4 precursor were successfully detected based on their tryptic fragments. CD163 and IL-1β were confirmed also by IHC. The protegrin-4 precursor was identified by MALDI-TOF/TOF directly on the tissue cryosections. CD163, IL-1β and protegrin-4 precursor were all significantly (p < 0.001) more expressed in necrotic areas of lungs infected by APP than in marginal zone, TBLN and in control lungs.

A Method to Quantify Tensile Biaxial Properties of Mouse Aortic Valve Leaflets

Understanding aortic valve (AV) mechanics is crucial in elucidating both the mechanisms that drive the manifestation of valvular diseases as well as the development of treatment modalities that target these processes. Genetically modified mouse models have become the gold standard in assessing biological mechanistic influences of AV development and disease. However, very little is known about mouse aortic valve leaflet (MAVL) tensile properties due to their microscopic size (∼500 μm long and 45 μm thick) and the lack of proper mechanical testing modalities to assess uniaxial and biaxial tensile properties of the tissue. We developed a method in which the biaxial tensile properties of MAVL tissues can be assessed by adhering the tissues to a silicone rubber membrane utilizing dopamine as an adhesive. Applying equiaxial tensile loads on the tissue–membrane composite and tracking the engineering strains on the surface of the tissue resulted in the characteristic orthotropic response of AV tissues seen in human and porcine tissues. Our data suggest that the circumferential direction is stiffer than the radial direction (n = 6, P = 0.0006) in MAVL tissues. This method can be implemented in future studies involving longitudinal mechanical stimulation of genetically modified MAVL tissues bridging the gap between cellular biological mechanisms and valve mechanics in popular mouse models of valve disease.

Surface Tension/Contact Angle Characters of Aprotic Binary Borneol-Dimethyl Sulphoxide Mixture

Borneol and dimethyl sulphoxide (DMSO) have been used as the skin penetration enhancers. Different concentrated borneol solutions in aprotic DMSO were prepared as the binary mixtures and determined their surface tension and contact angle behaviors using goniometer. Low borneol concentration minimized the surface tension and there was nearly stable contact angle for 30-70% borneol solutions. The trend contact angle value was decreased on glass slide, acrylic and LDPE whereas increasing on agarose gel and porcine tissues including buccal mucosa, gum and tongue with borneol concentration dependence. However, the borneol-DMSO binary mixture exhibited high wettability owing to its contact angle on glass surface was less than 90°. The solvent exchange between DMSO of borneol solutions and aqueous phase form agarose gel and porcine tissues including tongue, gum and buccal mucosa initiated the phase transformation from solution into matrix-like and promoted the higher contact angle with borneol concentration dependence. The understanding of surface tension and contact angle behaviors of aprotic borneol-DMSO binary mixture is useful for developing them into in situ forming gel for drug delivery such as in the oral cavity.