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Biomedical subjects

Lily Chang

Publications and source records attributed to Lily Chang.

16 recordsLinked to original sources
PubMed2006

Generalized approach for modeling minimally invasive surgery as a stochastic process using a discrete Markov model.

Minimally invasive surgery (MIS) involves a multidimensional series of tasks requiring a synthesis between visual information and the kinematics and dynamics of the surgical tools. Analysis of these sources of information is a key step in defining objective criteria for characterizing surgical performance. The Blue DRAGON is a new system for acquiring the kinematics and the dynamics of two endoscopic tools synchronized with the endoscopic view of the surgical scene. Modeling the process of MIS using a finite state model [Markov model (MM)] reveals the internal structure of the surgical task and is utilized as one of the key steps in objectively assessing surgical performance. The experimental protocol includes tying an intracorporeal knot in a MIS setup performed on an animal model (pig) by 30 surgeons at different levels of training including expert surgeons. An objective learning curve was defined based on measuring quantitative statistical distance (similarity) between MM of experts and MM of residents at different levels of training. The objective learning curve was similar to that of the subjective performance analysis. The MM proved to be a powerful and compact mathematical model for decomposing a complex task such as laparoscopic suturing. Systems like surgical robots or virtual reality simulators in which the kinematics and the dynamics of the surgical tool are inherently measured may benefit from incorporation of the proposed methodology.

Computer Simulation↗
PubMed2005

Typical GERD symptoms and esophageal pH monitoring are not enough to diagnose pharyngeal reflux.

BACKGROUND: Abnormal pharyngeal reflux of acid (PR) (as measured by pH monitoring) is associated with microaspiration, and is a good predictor of airway symptom response to medical and surgical anti-reflux therapy. However, in clinical practice the link between airway disease and Gastroesophageal reflux disease (GERD) is still based on the presence of typical symptoms (e.g., heartburn) and/or standard esophageal function testing (manometry and 24-pH monitoring). PR is rarely measured directly. We undertook this study to determine if typical symptoms and standard testing could reliably predict the presence of PR. METHODS: The study group consisted of 518 patients with suspected reflux induced airway disease evaluated from December 1998 through January 2002. Each patient completed a standardized symptom questionnaire, underwent esophageal manometry, and 24-h esophageal and pharyngeal pH monitoring. Patients were classified having abnormal pharyngeal reflux (PR+) if they had >1 episode of PR detected during pH monitoring. RESULTS: One hundred eighty-one patients were PR+ and 337 were PR-. The most common symptoms, namely cough (PR +73%, PR- 68%), hoarseness (PR +64%, PR- 66%), and dyspnea (PR +59%, PR- 59%) were present with similar incidence in PR+ and PR- patients. The incidence of heartburn was 54% in the PR+ and 52% in the PR- patients. Logistic regression analysis revealed that abnormal esophageal acid exposure was a predictor of PR+ (P < 0.001). Neither the presence of heartburn or specific respiratory symptoms, the pressure of the lower esophageal sphincter (LES) or upper esophageal sphincter (UES), or amplitude of esophageal contractions predicted PR+. There was substantial variability in esophageal length (UES to LES), thus the placement of the distal pH probe from the LES varied considerably (median = 13 cm, 2-20 cm). Using established normal values of acid exposure at multiple levels of the esophagus, 24% of PR+ patients had normal amounts of esophageal acid exposure. CONCLUSIONS: Typical GERD symptoms, such as heartburn, and typical symptoms of aspiration such as hoarseness, cough, or dyspnea are not enough to positively identify PR. While patients with abnormal esophageal acid exposure are three times more likely than those with normal values to have PR, abnormal esophageal acid exposure alone does not identify all patients with PR. Therefore, relying on symptoms and standard diagnostic testing may fail to identify patients with extraesophageal reflux. Pharyngeal pH monitoring should be considered for patients with suspected reflux-induced airway disease.

Diagnostic Techniques, Digestive System↗
PubMed2005

Robotic versus conventional laparoscopic skill acquisition: implications for training.

BACKGROUND AND PURPOSE: Despite the growing interest in surgical robotics, very little study has been done regarding the acquisition of the skills needed to perform robotic surgery safely. The purpose of this study was to determine whether skills are transferred between conventional laparoscopy and robotically assisted surgery. SUBJECTS AND METHODS: Intracorporeal knot tying was used for evaluating laparoscopic skills for time and error performance. Twenty medical students without any laparoscopic experience were randomized into two groups. Group A initially performed knot tying with conventional laparoscopic instruments, were trained with the daVinci Robotic System, and then performed knot tying with conventional laparoscopy. Group B performed knot tying with robotics, trained with standard laparoscopy, and completed post-training knot tying with robotics. Pretraining and post-training tasks were videotaped and analyzed using a detailed scoring system by one independent referee, who was blinded to the subjects' experience. RESULTS: Pre-training knot tying was faster with robotics (4.4 v 9.9 minutes; P < 0.001). The mean composite scores were 27.4 for group A and 57.4 for group B (P = 0.09), and the error scores were 57.1 and 42.1 (P = 0.29), respectively. Post-training time for knot completion decreased to 6.7 minutes and 3.4 minutes for groups A and B, respectively. Composite scores increased significantly, from 27.4 to 66.1 for group A and 57.4 to 81.8 for group B. Error scores decreased to 32.9 for group A (P = 0.1) and 16.2 in group B (P = 0.02). CONCLUSIONS: There appears to be reciprocal transfer of skills between conventional laparoscopy and robotically assisted surgery. However, this transference is incomplete. Our results suggest that training with either technique or conventional laparoscopy is superior to training with robotics alone.

Clinical Competence↗
PubMed2004

Lipopolysaccharide-induced changes in rat gastric H/K-ATPase expression.

OBJECTIVE: To evaluate lipopolysaccharide (LPS)-induced inhibition of gastric acid secretion. SUMMARY BACKGROUND DATA: Endotoxemia from LPS inhibits gastric acid secretion by an unknown mechanism. Bacterial overgrowth in the stomach caused by decreased acid secretion could be responsible for nosocomial pneumonia developing in critically ill intensive care unit patients. Because acid secretion is via the H/K-ATPase and the effects of LPS on this enzyme are unknown, we hypothesized that LPS causes inhibition of gastric acid secretion by down-regulating the H/K-ATPase. METHODS: A rat model to study gastric acid secretion was created. Saline or LPS (0.05-20 mg/kg IP) was given for 1 hour, after which basal acid secretion was determined for 1 hour. Pentagastrin (PG; 10 microg/kg IV) or saline was then given and gastric acid output collected for another 2 hours. RESULTS: LPS dose dependently inhibited basal and PG stimulated acid secretion. LPS increased alpha- and beta-H/K-ATPase subunit mRNA expression (Northern blot) in the absence of PG compared with saline. In the presence of PG, LPS did not have this effect. Western blot analysis did not show any difference in alpha- or beta-subunit immunoreactivity. Immunofluorescence analysis demonstrated that PG increased staining in the secretory membranes for H/K-ATPase subunits whereas in all LPS-treated rats, it appeared that H/K-ATPase subunits remained within the tubulovesicles. Furthermore, changes in H/K-ATPase mRNA expression may not be related to changes in NF-kappaB activity. CONCLUSIONS: These data suggest that inhibition of gastric acid secretion by LPS is due to inhibition of H/K-ATPase enzymatic function or changes in cytoskeletal rearrangements in H/K-ATPase subunits rather than by down-regulation of transcriptional or translational events.

Animals↗
PubMed2004

Quantifying surgeon grasping mechanics in laparoscopy using the Blue DRAGON system.

Mechanical testing of abdominal organs has a profound impact on surgical simulation and surgical robotics development. Due to the nonlinear and viscoelastic nature of soft tissue it is crucial to test them in surgically relevant ranges of applied force, deformation, and duration for incorporating haptic realism into surgical simulators and for safe operation of surgical robots. In order to determine these ranges, a system known as the Blue DRAGON was used to track the motions and the forces applied to surgical tools during live procedures for quantifying how surgeons typically perform a minimally invasive surgical procedure. Thirty-one surgeons of varying skill were recorded performing three different surgical tasks. Grasping force (as applied to the tool handles) and handle angle for each tool were the signals of interest among 26 channels total acquired by the system in real time. These data were analyzed for their magnitudes and frequency content. Using the tool contact state, an algorithm selected tissue grasps to analyze measures during grasps only, as well as obtain grasp durations. The mean force applied to the tool handles during tissue grasps was 8.52 N +/- 2.77 N; maximum force was 68.17 N. Ninety-five percent of the handle angle frequency content was below 1.98 Hz +/- 0.98 Hz. Average grasp time was 2.29 s +/- 1.65 s, and 95% of all grasps were held for 8.86 s +/- 7.06 s or less. The average maximum grasp time during these tasks was 13.37 s +/- 11.42 s. These results form the basis for determining how abdominal tissues are to be mechanically tested in ranges and durations of force and deformation that are surgically realistic. Additionally, this information may serve as design specifications for new surgical robots or haptic simulators.

Animals↗
PubMed2004

Optimization of a vector quantization codebook for objective evaluation of surgical skill.

Surgical robotic systems and virtual reality simulators have introduced an unprecedented precision of measurement for both tool-tissue and tool-surgeon interaction; thus holding promise for more objective analyses of surgical skill. Integrative or averaged metrics such as path length, time-to-task, success/failure percentages, etc., have often been employed towards this end but these fail to address the processes associated with a surgical task as a dynamic phenomena. Stochastic tools such as Markov modeling using a 'white-box' approach have proven amenable to this type of analysis. While such an approach reveals the internal structure of the of the surgical task as a process, it requires a task decomposition based on expert knowledge, which may result in a relatively large/complex model. In this work, a 'black box' approach is developed with generalized cross-procedural applications., the model is characterized by a compact topology, abstract state definitions, and optimized codebook size. Data sets of isolated tasks were extracted from the Blue DRAGON database consisting of 30 surgical subjects stratified into six training levels. Vector quantization (VQ) was employed on the entire database, thus synthesizing a lexicon of discrete, task-independent surgical tool/tissue interactions. VQ has successfully established a dictionary of 63 surgical code words and displayed non-temporal skill discrimination. VQ allows for a more cross-procedural analysis without relying on a thorough study of the procedure, links the results of the black-box approach to observable phenomena, and reduces the computational cost of the analysis by discretizing a complex, continuous data space.

Algorithms↗
PubMed2003

Improved outcome after extended gastric myotomy for achalasia.

HYPOTHESIS: There is general agreement that a Heller myotomy should extend 6 to 7 cm above the gastroesophageal junction. Results of most previous studies have recommended that the myotomy extend 1 to 1.5 cm below the gastroesophageal junction. We speculated that the effectiveness of the operation could be improved if a longer, 3-cm myotomy was carried out below the gastroesophageal junction, as it would more completely obliterate the lower esophageal sphincter. We, therefore, changed our technique in 1998. Concurrently, we converted from a Dor fundoplication to a Toupet fundoplication. This study analyzes the results of our new strategy. DESIGN: A case series using a prospectively maintained database. SETTING: Tertiary referral center. PATIENTS: One hundred ten consecutive patients with achalasia undergoing laparoscopic Heller myotomy. INTERVENTION: We analyzed the course of 52 patients treated with a standard laparoscopic esophagogastric myotomy (1.5 cm in the stomach) and a Dor fundoplication between September 1, 1994, and August 31, 1998, and 58 treated with an extended gastric myotomy (3 cm below the gastroesophageal junction) and a Toupet fundoplication between September 1, 1998, and August 31, 2001. MAIN OUTCOME MEASURES: Esophageal function testing (esophageal manometry and 24-hour pH monitoring), symptom questionnaire (frequency and severity), and postoperative interventions required. RESULTS: Postoperatively the lower esophageal sphincter pressure was significantly lower after extended gastric myotomy and a Toupet fundoplication vs standard myotomy and a Dor fundoplication (9.5 vs 15.8 mm Hg). Dysphagia was both less frequent (1.2 vs 2.1) and less severe (visual analog scale, 3.2 vs 5.3) after extended gastric myotomy and Toupet fundoplication. In the standard laparoscopic esophagogastric myotomy and a Dor fundoplication group, 9 patients (17%) had recurrent, severe dysphagia, which was treated by dilation in 5 patients and by reoperation in 4 patients. In the extended gastric myotomy and Toupet fundoplication group, 2 patients (3%) developed recurrent dysphagia that resolved with dilatation. There were no reoperations in the extended gastric myotomy and Toupet fundoplication group. No difference was noted in the frequency of heartburn (1.3 vs 1.7), regurgitation (0.3 vs 0.8), and chest pain (0.3 vs 0.6), nor was there a difference between the 2 groups in proximal (1.7% vs 2.3%) and distal (6.0% vs 5.9%) esophageal acid exposure. CONCLUSION: An extended gastric myotomy (3 cm) more effectively disrupts the lower esophageal sphincter, thus improving the results of surgical therapy for achalasia for dysphagia without increasing the rate of abnormal gastroesophageal reflux provided that a Toupet fundoplication is added.

Deglutition Disorders↗
PubMed2003

The use of small intestine submucosa in the repair of paraesophageal hernias: initial observations of a new technique.

BACKGROUND: Recent reports suggest that when laparoscopy is used to repair paraesophageal hernias recurrence rates reach 20% to 40%. Tension-free hernia closure with synthetic mesh reduces recurrence but occasionally results in esophageal injury. We hypothesized that reinforcement of the hiatal closure with small intestine submucosa (SIS) mesh, in some unusually large hernias, might reduce recurrence rates without causing injury to the esophagus. METHODS: From January 2001 to March 2002 we treated 18 large paraesophageal hernias via a laparoscopic approach. In 9 of the largest hernias (one type II and 8 type III, of which 1 was recurrent) the repair was reinforced with SIS mesh (Surgisis, Cook Surgical) and represent the subjects of this study. Nissen fundoplication with gastropexy was performed in all patients. Clinical follow-up ranged from 3 to 16 months (median 8). Every patient was evaluated with barium esophagram or endoscopy or both 1 to 8 months (median 2) postoperatively. RESULTS: The presenting symptoms were postprandial pain/fullness (9 of 9), heartburn (4 of 9), anemia (4 of 9), dysphagia (3 of 9), regurgitation (3 of 9), and chest pain (3 of 9). One patient died of a hemorrhagic stroke within 30 days of the operation. Postoperatively, presenting symptoms resolved (83%) or improved (17%) in each of the remaining 8 patients. One patient required endoscopic dilation for mild dysphagia. Seven of 8 patients had a normal barium esophagram without evidence of hernia. One morbidly obese (body mass index = 47) patient had a small (2 cm) sliding hiatal hernia postoperatively. There were no other complications, and specifically no perforations or mesh erosions. CONCLUSIONS: These observations suggest that the use of SIS in the repair of paraesophageal hernias is safe and may reduce recurrence. Longer follow-up and a randomized study are needed to validate these results.

Aged↗
PubMed2003

Effects of ketamine/xylazine on expression of tumor necrosis factor-alpha, inducible nitric oxide synthase, and cyclo-oxygenase-2 in rat gastric mucosa during endotoxemia.

Some anesthetics attenuate expression of endotoxin-induced production of proinflammatory genes. The anesthetic combination of ketamine/xylazine (K/X) decreases lipopolysaccharide (LPS)-induced liver injury in rats. However, the effects of K/X on gut function and gene expression are unknown. The purpose of this study was to examine the effect of K/X on LPS-induced gastric fluid accumulation, and gastric tumor necrosis factor (TNF)-alpha, inducible nitric oxide synthase (iNOS), and cyclo-oxygenase (COX)-2 expression, as well as serum TNF-alpha protein levels over time. We hypothesized that K/X would attenuate these LPS-induced endpoints. Rats were given either intraperitoneal saline or K (70 mg/kg) and X (6 mg/kg) 1 h before saline or LPS (20 mg/kg i.p.) treatment of 1, 3, or 5 h. Serum and gastric fluid and mucosa were collected and TNF-alpha, iNOS, and COX-2 expression were determined. LPS caused a significant increase in early serum and gastric mucosal TNF-alpha protein expression at 1 h, an effect that was significantly attenuated by K/X pretreatment. LPS caused significant gastric stasis and increased iNOS and COX-2 mRNA expression and iNOS protein expression in the stomach when compared with controls. K/X attenuated LPS-induced gastric fluid accumulation and upregulation of iNOS mRNA and protein, but not COX-2. These data indicate that K/X inhibits some proinflammatory genes and pathophysiologic responses in the serum and stomach during endotoxemia. The effects of K/X appear to inhibit transcriptional events in iNOS expression, which may be dependent on K/X-induced inhibition of early TNF-alpha expression. Furthermore, in rat models of endotoxemia, especially those evaluating the stomach, careful consideration needs to be given if anesthetic combinations with ketamine and/or xylazine are used, as they alter LPS-induced responses.

Animals↗
PubMed2003

In-vivo and in-situ compressive properties of porcine abdominal soft tissues.

Accurate biomechanical characteristics of tissues are essential for developing realistic virtual reality surgical simulators utilizing haptic feedback. Surgical simulation technology has progressed rapidly but lacks a comprehensive database of soft tissue mechanical properties with which to incorporate. Simulators are often designed purely based on what "feels right;" quantitative empirical data are lacking. A motorized endoscopic grasper was used to test abdominal porcine tissues in-vivo and in-situ with cyclic and static compressive loadings. An exponential constitutive equation was fit to the resulting stress-strain curves, and the coefficients were compared for various conditions. Stress relaxation for liver and small bowel were also examined. Differences between successive squeezes and between in-vivo and in-situ conditions were found.

Abdomen↗
PubMed2003

Minimally invasive surgery task decomposition--etymology of endoscopic suturing.

The analogy between Minimally Invasive Surgery (MIS) and the human language inspires the decomposition of a surgical task into its primary elements. The frequency of different elements or words" and their sequential associations or "grammar" both hold critical information about the process and outcome of the procedure. Modeling these sequential element expressions using a multi finite states model (Markov model) reveals the grammatical structure of the surgical task and is utilized as one of the key steps in objectively assessing surgical performance. The experimental protocol included 30 surgeons at different levels of training (5xR1,R2,R3,R4,R5, and experts) performing Laparoscopic suturing on an animal model (pig). The kinematics and dynamics of left and right endoscopic tools along with the visual view of the surgical scene were acquired by the Blue DRAGON system. The methodology of decomposing the surgical task is based on a fully connected, finite-states (30 states) Markov model (MM) where the left and right hands are represented by 15 states each. In addition to the MM objective analysis, a scoring protocol was used by an expert surgeon to subjectively assess the subjects' technical performance. An objective learning curve was defined based on measuring quantitative statistical distance (similarity) between MM of experts and MM of residents at different levels of training. The objective learning curve (e.g. statistical distance between MM) was similar to that of the subjective performance analysis. The MM proved to be a powerful and compact mathematical model for decomposing a complex task such as laparoscopic suturing. Systems like surgical robots or virtual reality simulators that inherently measure the kinematics and dynamics of the surgical tool may benefit from inclusion of the proposed methodology for analysis of efficacy and objective evaluation of surgical skills during training.

Endoscopy↗
PubMed2002

Induction of NF-kappaB, IkappaB-alpha, and iNOS in rat gastric mucosa during endotoxemia.

Upregulation of inducible nitric oxide synthase (iNOS) contributes to the development of gastric injury during endotoxemia. The molecular mechanisms related to its induction are unknown. Because the transcription factor nuclear factor-kappa B (NF-kappaB) regulates inflammatory genes in response to endotoxemia, we hypothesized that its activity in gastric mucosa would increase while its inhibitor IkappaB-alpha would decrease commensurate with changes in iNOS expression. Rats were given intraperitoneal saline or lipopolysaccharide (LPS; 20 mg/kg) for 5, 15, or 30 min, or for 1, 3, or 5 h, and killed, and the gastric mucosa was prepared for determination of iNOS and IkappaB-alpha by Western immunoblotting, iNOS mRNA by quantitative real-time RT-PCR, and NF-kappaB by electrophoretic mobility-shift assay. LPS caused a significant increase in iNOS mRNA and protein immunoreactivity at 1, 3, and 5 h compared to controls. NF-kappaB-binding activity increased in the nuclear fraction of gastric mucosa at 1 h and steadily increased over time after LPS administration. The activated NF-kappaB consisted mainly of p50 with a lesser amount of p65 subunits as demonstrated by a supershift assay. IkappaB-alpha decreased in gastric cytosolic fractions over time, consistent with its degradation. These data suggest that during endotoxemia expression of the inflammatory mediator iNOS in the gastric mucosa may be upregulated by degradation of IkappaB-alpha and subsequent translocation of NF-kappaB into the nucleus and increased NF-kappaB activity.

Animals↗
PubMed2002

Gastric nitric oxide synthase expression during endotoxemia: implications in mucosal defense in rats.

BACKGROUND & AIMS: This study was performed to examine expression of gastric nitric oxide synthase (NOS) isoforms during endotoxemia in rats and to assess their role(s) in gastric injury from bile and ethanol. METHODS: Lipopolysaccharide (LPS) enhanced the expression and activity of inducible nitric oxide synthase in gastric mucosa in a dose- and time-dependent manner. RESULTS: Endothelial nitric oxide synthase and neural nitric oxide synthase expression did not significantly change, but constitutive nitric oxide synthase activity decreased over time. LPS alone caused injury to the gastric mucosa and disrupted F-actin filaments in the same cells with enhanced immunostaining for inducible nitric oxide synthase. LPS also exacerbated gastric injury from the mild irritants 5 mmol/L acidified taurocholate and 20% ethanol as did local intra-arterial infusion of the nitric oxide donor S-nitroso-N-acetyl-penicillamine. The selective inducible nitric oxide synthase inhibitor aminoguanidine negated LPS-induced exacerbation of gastric injury from these irritants. The nonselective NOS inhibitor N(G)-nitro-L-arginine methyl ester augmented the deleterious effects of LPS, an effect reversed by L-arginine but not D-arginine. Aminoguanidine, but not N(G)-nitro-L-arginine methyl ester, negated LPS-induced accumulation of gastric luminal nitrates. CONCLUSIONS: These data suggest that increased inducible NOS activity and decreased constitutive nitric oxide synthase activity are primarily responsible for exacerbating gastric injury from luminal irritants during endotoxemia. Moreover, septic patients may be more susceptible to gastric injury from bile during gastrointestinal ileus.

Animals↗
PubMed2002

Does upregulation of inducible nitric oxide synthase play a role in hepatic injury?

Lipopolysaccharide (LPS) and gut ischemia/reperfusion (I/R) injury cause reversible liver injury. Because nitric oxide (NO) can have both beneficial and deleterious effects in the gastrointestinal tract, and because the role of NO in gut I/R-induced hepatic injury is unknown, this study examined its role in LPS and gut I/R-induced hepatic injury in the rat. Both LPS and gut I/R caused a similar increase in serum hepatocellular enzymes. LPS but not gut I/R caused a significant increase in upregulation of hepatic inducible NO synthase (iNOS) according to quantitative real-time RT-PCR and Western immunoblot analysis. Aminoguanidine, a selective iNOS inhibitor, attenuated LPS-induced hepatic injury and hypotension, but did not prevent gut I/R-induced hepatic injury. In contrast, the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester aggravated liver damage from both LPS and gut I/R. These data indicate that iNOS plays a role in mediating LPS-induced hepatic injury, but not gut I/R-induced hepatic injury. The data also suggest that the constitutive isoforms of NOS play a hepatoprotective role in both models of hepatic injury.

Anesthetics↗
PubMed2002

The Blue DRAGON--a system for monitoring the kinematics and the dynamics of endoscopic tools in minimally invasive surgery for objective laparoscopic skill assessment.

Minimally invasive surgeiy (MIS) involves a multi-dimensional series of tasks requiring a synthesis between visual information and the kinematics and dynamics of the surgical tools. Analysis of these sources of information is a key step in mastering MIS surgery but may also be used to define objective criteria for characterizing surgical performance. The BIueDRAGON is a new system for acquiring the kinematics and the dynamics of two endoscopic tools along with the visual view of the surgical scene. It includes two four-bar mechanisms equipped with position and force torque sensors for measuring the positions and the orientations (P/O) of two endoscopic tools along with the forces and torques applied by the surgeons hands. The methodology of decomposing the surgical task is based on a fully connected, finite-states (28 states) Markov model where each states corresponded to a fundamental tool/tissue interaction based on the tool kinematics and associated with unique F/T signatures. The experimental protocol included seven MIS tasks performed on an animal model (pig) by 30 surgeons at different levels of their residency training. Preliminary analysis of these data showed that major differences between residents at different skill levels were: (i) the types of tool/tissue interactions being used, (ii) the transitions between tool/tissue interactions being applied by each hand, (iii) time spent while perfonning each tool/tissue interaction, (iv) the overall completion time, and (v) the variable F/T magnitudes being applied by the subjects through the endoscopic tools. Systems like surgical robots or virtual reality simulators that inherently measure the kinematics and the dynamics of the surgical tool may benefit from inclusion of the proposed methodology for analysis of efficacy and objective evaluation of surgical skills during training.

Animals↗