David A. McClusky

Construct validation of the ProMIS simulator using a novel laparoscopic suturing task

BackgroundThe use of simulation for minimally invasive surgery (MIS) skills training has many advantages over current traditional methods. One advantage of simulation is that it enables an objective assessment of technical performance. The purpose of this study was to determine whether the ProMIS augmented reality simulator could objectively distinguish between levels of performance skills on a complex laparoscopic suturing task.MethodsTen subjects — five laparoscopic experts and five laparoscopic novices — were assessed for baseline perceptual, visio-spatial, and psychomotor abilities using validated tests. After three trials of a novel laparoscopic suturing task were performed on the simulator, measures for time, smoothness of movement, and path distance were analyzed for each trial. Accuracy and errors were evaluated separately by two blinded reviewers to an interrater reliability of >0.8. Comparisons of mean performance measures were made between the two groups using a Mann-Whitney U test. Internal consistency of ProMIS measures was assessed with coefficient α.ResultsThe psychomotor performance of the experts was superior at baseline assessment (p < 0.001). On the laparoscopic suturing task, the experts performed significantly better than the novices across all three trials (p < 0.001). They performed the tasks between three and four times faster (p < 0.0001), had three times shorter instrument path length (p < 0.0001), and had four times greater smoothness of instrument movement (p < 0.009). Experts also showed greater consistency in their performance, as demonstrated by SDs across all measures, which were four times smaller than the novice group. Observed internal consistency of ProMIS measures was high (α = 0.95, p < 0.00001).ConclusionsPreliminary results of construct validation efforts of the ProMIS simulator show that it can distinguish between experts and novices and has promising psychometric properties. The attractive feature of ProMIS is that a wide variety of MIS tasks can be used to train and assess technical skills.

When fundoplication fails: redo?

Objective:The largest series in the literature dealing with redo fundoplication was presented and published in 1999 and included 100 patients. Herein we update this initial series of 100, with 207 additional patients who have undergone redo fundoplication (n = 307). Summary Background Data:Increasing numbers of patients are failing esophagogastric fundoplication and requiring redo procedures. Data regarding the nature of these failures have been scant. Methods:Data on all patients undergoing foregut surgery are collected prospectively. Between 1991 and 2004, 307 patients underwent redo fundoplication for the management of anatomic complications or recurrent GERD. Statistical analysis was performed with multiple χ2 and Mann-Whitney U analyses, as well as ANOVA. Results:Between 1991 and 2004, 1892 patients underwent primary fundoplication for GERD (1734) or paraesophageal hernia (158). Of these, 54 required redo fundoplication (2.8%). The majority of failures (73%) were managed within 2 years of the initial operation (P = 0.0001). The mechanism of failure was transdiaphragmatic wrap herniation in 33 of 54 (61%). In the 231 patients who underwent fundoplication elsewhere, 109 had transdiaphragmatic herniation (47%, P = NS). In this group of 285 patients, 22 (8%) required another redo (P = NS). The majority of the procedures were initiated laparoscopically (240/307, 78%), with 20 converted (8%). Overall mortality was 0.3%. Conclusions:Failure of fundoplication is unusual in experienced hands. Most are managed within 2 years of the initial operation. Wrap herniation has now become the most common mechanism of failure requiring redo. Redo fundoplication was successful in 93% of patients, and most could be safely handled laparoscopically.

Relationship Between Tissue Ingrowth and Mesh Contraction

Contraction is a well-documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 × 10 cm2. After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0–4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 ± 7 cm2) was significantly larger than the area covered by the PP meshes (67 ± 14 cm2) (p = 0.006). Tissue ingrowth force of the PE meshes (194 ± 37 N) had a trend toward being higher than that of the PP meshes (159 ± 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05–0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size.

Objective psychomotor skills assessment of experienced and novice flexible endoscopists with a virtual reality simulator

The objective of this study was to determine whether the GI Mentor II virtual reality simulator can distinguish the psychomotor skills of intermediately experienced endoscopists from those of novices, and do so with a high level of consistency and reliability. A total of five intermediate and nine novice endoscopists were evaluated using the EndoBubble abstract psychomotor task. Each subject performed three repetitions of the task. Performance and error data were recorded for each trial. The intermediate group performed better than the novice group in each trial. The differences were significant in trial 1 for balloons popped (P = .001), completion time (P = .04), and errors (P = .03). Trial 2 showed significance only for balloons popped (P = .002). Trial 3 showed significance for balloons popped (P = .004) and errors (P = .008). The novice group showed significant improvement between trials 1 and 3 (P < 0.05). No improvement was noted in the intermediate group. Measures of consistency and reliability were greater than 0.8 in both groups with the exception of novice completion time where test-retest reliability was 0.74. The GI Mentor II simulator can distinguish between novice and intermediate endoscopists. The simulator assesses skills with levels of consistency and reliability required for high-stakes assessment.

Laparoscopic parastomal hernia repair using a nonslit mesh technique

BackgroundThe management of parastomal hernia is associated with high morbidity and recurrence rates (20–70%). This study investigated a novel laparoscopic approach and evaluated its outcomes.MethodsA consecutive multi-institutional series of patients undergoing parastomal hernia repair between 2001 and 2005 were analyzed retrospectively. Laparoscopy was used with modification of the open Sugarbaker technique. A nonslit expanded polytetrafluoroethylene (ePTFE) mesh was placed to provide 5-cm overlay coverage of the stoma and defect. Transfascial sutures secured the mesh, allowing the stoma to exit from the lateral edge. Five advanced laparoscopic surgeons performed all the procedures. The primary outcome measure was hernia recurrence.ResultsA total of 25 patients with a mean age of 60 years and a body mass index of 29 kg/m2 underwent surgery. Six of these patients had undergone previous mesh stoma revisions. The mean size of the hernia defect was 64 cm2, and the mean size of the mesh was 365 cm2. There were no conversions to open surgery. The overall postoperative morbidity was 23%, and the mean hospital length of stay was 3.3 days. One patient died of pulmonary complications; one patient had a trocar-site infection; and one patient had a mesh infection requiring mesh removal. During a median follow-up period of 19 months (range, 2–38 months), 4% (1/25) of the patients experienced recurrence.ConclusionOn the basis of this large case series, the laparoscopic nonslit mesh technique for the repair of parastomal hernias seems to be a promising approach for the reduction of hernia recurrence in experienced hands.

Real-Time Objective Assessment of Knot Quality With a Portable Tensiometer Is Superior to Execution Time for Assessment of Laparoscopic Knot-Tying Performance:

Objective: Laparoscopic intracorporeal knot tying is a difficult skill to acquire. Currently, time to complete a knot is the most commonly used metric to assess the acquisition of this skill; however, without a measure of knot quality, time is a poor indicator of skills mastery. Others have shown that knot quality can be accurately assessed with a tensiometer, but obtaining this type of assessment has typically been cumbersome. We investigated a new method of real-time assessment of knot quality that allows for more practical use of knot quality as a performance metric. Methods: Eleven experienced endoscopic surgeons tied 100 intracorporeal knots in a standard box trainer. Each of the knots was immediately tested using the InSpec 2200 benchtop tensiometer (INSTRON, Canton MA) where a knot quality score (KQS) is generated based on the load handling properties of the knotted suture. The execution time was also recorded for each knot. Results: The assessment of all knots ended with one of two end points: knots that slipped (n = 48)or knots that held until the suture broke (n = 52). Knots that slip are generally of poorer quality than those that held. Execution time did not correlate with knot-quality score (r= 0.009, P= .9), and the mean execution time did not differ significantly between slipped and held knots (65 vs 68 seconds, P= .8). No completion time criteria were able to accurately predict slipped versus held knots. The mean KQS difference between held and slipped knots was highly significant (24 vs 12, P< .0001). A knot with a KQS exceeding 20 was nearly 10 times more likely to hold than slip. Conclusion: Time to complete a knot is a poor metric for the objective assessment of intracorporeal knot-tying performance in the absence of a measure of knot quality. Real-time evaluation of the knot quality can accurately distinguish welltied knots from poorly tied knots. This mode of assessment should be incorporated into training curriculum for surgical knot tying.

Hepatic Surgery and Hepatic Surgical Anatomy: Historical Partners in Progress

Abstract. Whether for hepatic trauma or transplantation, a surgeon’s knowledge of hepatic anatomy commonly determines a patient’s outcome. The first medically relevant anatomic studies of the liver emerged with the endeavors of Herophilus and Erasistratus between 310 and 280 bc . Yet it was not until after the development of anesthesia and antisepsis that the first formal resections were performed during the late 1800s. After vascular occlusion principles had been developed as a means of successful hemorrhage control, several deliberate attempts were made to repair the liver surgically. Such efforts culminated in the work of Wendel in 1910 when he followed avascular planes during hepatectomy. The functional anatomy of surgery and surgical technique had suddenly joined in an effort to advance the practice, and eventually the efficacy of hepatic surgeons in facilitating the modern era of segmental anatomy extended hepatectomies and transplantation surgery.

The American College of Surgeons/Association of Program Directors in Surgery National Skills Curriculum: adoption rate, challenges and strategies for effective implementation into surgical residency programs.

BACKGROUND The American College of Surgeons/Association of Program Directors in Surgery (ACS/APDS) National Skills Curriculum is a 3-phase program targeting technical and nontechnical skills development. Few data exist regarding the adoption of this curriculum by surgical residencies. This study attempted to determine the rate of uptake and identify implementation enablers/barriers. METHODS A web-based survey was developed by an international expert panel of surgical educators (5 surgeons and 1 psychologist). After piloting, the survey was sent to all general surgery program directors via email link. Descriptive statistics were used to determine the residency program characteristics and perceptions of the curriculum. Implementation rates for each phase and module were calculated. Adoption barriers were identified quantitatively and qualitatively using free text responses. Standardized qualitative methodology of emergent theme analysis was used to identify strategies for success and details of support required for implementation. RESULTS Of the 238 program directors approached, 117 (49%) responded to the survey. Twenty-one percent (25/117) were unaware of the ACS/APDS curriculum. Implementation rates for were 36% for phase I, 19% for phase II, and 16% for phase III. The most common modules adopted were the suturing, knot-tying, and chest tube modules of phase I. Over 50% of respondents identified lack of faculty protected time, limited personnel, significant costs, and resident work-hour restrictions as major obstacles to implementation. Strategies for effective uptake included faculty incentives, adequate funding, administrative support, and dedicated time and resources. CONCLUSION Despite the availability of a comprehensive curriculum, its diffusion into general surgery residency programs remains low. Obstacles related to successful implementation include personnel, learner, and administrative issues. Addressing these issues may improve the adoption rate of the curriculum.

Tribute to a Triad: History of Splenic Anatomy, Physiology, and Surgery—Part 2

By the early 1900s it was widely accepted that the efforts of Wells, Bryant, Kaznelson, and Micheli necessitated a surgical appreciation of the pathophysiologic activities of the spleen. The respect bestowed on the diseased spleen, however, did not cohere to its healthy prototype. What else could explain Du Bois-Reymond’s telling statement of the late 1800s: “Now we come to the spleen, of it we know nothing. So much for the spleen” [1]. The essential question remained: “Este igitur splenatam necessarius?” The answer continued to be “no” well into the twentieth century. Despite Du Bois-Reymond’s sentiments, this resounding “no” did not indicate a lack of physiologic knowledge. Sir William Osler once commented, “Of the physiology of the spleen we know really very little.” To this, he quickly added, “That it is concerned with the process of blood scavenging; that it acts as a sort of warehouse for blood pigments; and that its structure in parts indicates hematopoiesis—these are about the only functions which are recognized” [2]. In 1928 William Mayo added his opinions on the topic while imparting an immunologic role to the spleen as well. He wrote:

Characterization of resident surgeon participation during carotid endarterectomy and impact on perioperative outcomes

INTRODUCTION The impact of resident surgeon participation during vascular procedures on postoperative outcomes is incompletely understood. We characterized resident physician participation during carotid endarterectomy (CEA) procedures within the 2005-2009 American College of Surgeons National Surgical Quality Improvement Participant Use Datafile and evaluated associations with procedural characteristics and perioperative adverse events. METHODS CEAs were identified using primary current procedural terminology codes; those performed simultaneously with other major procedures or unknown resident participation status were excluded. Group-wise comparisons based on resident participation status were performed using χ(2) or Fishers exact test for categorical variables and t tests or nonparametric methods for continuous variables. Associations with perioperative adverse events (major = stroke, death, myocardial infarction, or cardiac arrest; minor = peripheral nerve injury, bleeding requiring transfusion, surgical site infection, or wound disruption) were assessed using multivariable logistic regression models adjusting for other known risk factors. RESULTS A total of 25,280 CEA procedures were analyzed, of which residents participated in 13,705 (54.2%), while residents were absent in 11,575 (45.8%). Among CEAs with resident physician participation, resident level was categorized as junior (postgraduate year [PGY] 1-2) in 21.9%, senior (PGY 3-5) in 52.7%, and fellow (PGY ≥6) in 25.3%. Major adverse event rates with and without resident participation were 1.9% versus 2.1%, and minor adverse event rates with and without resident participation were 0.9% versus 1.0%, respectively. In multivariable models, resident physician participation was not associated with perioperative risk for major adverse events (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.75-1.08) or minor adverse events (OR, 0.93; 95% CI, 0.72-1.21). CONCLUSIONS Resident surgeon participation during CEA is not associated with risk of adverse perioperative events.