Application of Design Structure Matrix to Simulate Surgical Procedures and Predict Surgery Duration.

BACKGROUND: The complexities of surgery require an efficient and explicit method to evaluate and standardize surgical procedures. A reliable surgical evaluation tool will be able to serve various purposes such as development of surgery training programs and improvement of surgical skills. OBJECTIVES: (a) To develop a modeling framework based on integration of dexterity analysis and design structure matrix (DSM), to be generally applicable to predict total duration of a surgical procedure, and (b) to validate the model by comparing its results with laparoscopic cholecystectomy surgery protocol. METHOD: A modeling framework is developed through DSM, a tool used in engineering design, systems engineering and management, to hierarchically decompose and describe relationships among individual surgical activities. Individual decomposed activities are assumed to have uncertain parameters so that a rework probability is introduced. The simulation produces a distribution of the duration of the modeled procedure. A statistical approach is then taken to evaluate surgery duration through integrated numerical parameters. The modeling framework is applied for the first time to analyze a surgery; laparoscopic cholecystectomy, a common surgical procedure, is selected for the analysis. RESULTS: The present simulation model is validated by comparing its results of predicted surgery duration with the standard laparoscopic cholecystectomy protocols from the Atlas of Minimally Invasive Surgery with 2.5% error and that from the Atlas of Pediatric Laparoscopy and Thoracoscopy with 4% error. CONCLUSION: The present model, developed based on dexterity analysis and DSM, demonstrates a validated capability of predicting laparoscopic cholecystectomy surgery duration. Future studies will explore its potential applications to other surgery procedures and in improving surgeons' performance and training novices.

Pediatric aortoiliac injury following blunt abdominal trauma: A case report.

INTRODUCTION: The most common mechanism of aortic injury involves motor vehicle collisions resulting in aortic disruptions, occurring almost exclusively in the chest. Injury to the abdominal aorta following blunt trauma is nearly twenty times less likely to occur than the thoracic aorta. Because of the low incidence, there are few reports regarding the presentation and repair of these particular injuries, especially in the pediatric population. PRESENTATION OF CASE: We present a case of a 7-year-old boy involved in a high speed motor vehicle accident with an abdominal aorta transection at the aortic bifurcation extending into the left iliac artery. The injury was repaired using bovine pericardium with the adventitia and intima of the vessel approximated over the bovine bridge. DISCUSSION: Primary repair of thoracic aortic injury has been thoroughly described in the literature with good outcomes yet, abdominal aortic repair remains ambiguous. Few techniques and materials have been described with even less data surrounding the long-term outcomes. CONCLUSION: Bovine pericardium is a strong and stable acellular collagenous material with the potential to accelerate endothelialization and tissue regeneration. This remains an interesting field of research as stenosis and pseudo-coarction data have yet to be determined.

Trichobezoar presenting as a gastric outlet obstruction: A case report.

INTRODUCTION: Rapunzel syndrome is a rare intestinal condition that starts with the ingestion of a trichobezoar. The condition is predominately found in females and can be associated with trichotillomania, or the compulsive urge to pull one's own hair out. There are less than 40 cases described in the literature with the prevention of recurrence aimed at psychological treatment. PRESENTATION OF CASE: The patient is a 7 year-old girl with a history of trichotillomania with trichophagia as a young child who presented with abdominal pain, nausea, and vomiting, consistent with a gastric outlet obstruction. She had an exploratory laparotomy with gastrostomy performed revealing a 18cm by 18cm trichobezoar with extension into the small bowel. DISCUSSION: Bezoars, an already rare entity, can occasionally lead to gastric and small bowel obstructions. Small collections of ingested hair build up in the intestinal tract causing significant symptoms. These obstructions can sometimes be treated through minimally invasive techniques but, in our case described, it is unlikely to have been treated any other way due to the substantial size of the trichobezoar. CONCLUSION: Early consideration of Rapunzel syndrome is important in young females presenting with a gastric outlet obstruction.

Rapidly enlarging neck mass in a neonate causing airway compromise.

Up to 20% of all congenital pediatric head and neck masses are branchial cleft cysts. Second branchial cleft cysts account for 95% of branchial anomalies, and fourth branchial cleft cysts are the rarest type. Their typical presentations include non-life-threatening symptoms, such as drainage, skin irritations, minor swelling, and tenderness. We describe a 5-week-old neonate with increasing stridor secondary to a rapidly growing neck mass. Imaging and surgical excision confirmed the mass to be an infected fourth branchial cleft cyst.

Tuning a MAb glycan profile in cell culture: Supplementing N-acetylglucosamine to favour G0 glycans without compromising productivity and cell growth.

Glycosylation is a critical quality attribute of many therapeutic proteins, particularly monoclonal antibodies (MAbs). Nucleotide-sugar precursors supplemented to growth medium to affect the substrate supply chain of glycosylation has yielded promising but varied results for affecting glycosylation. Glucosamine (GlcN), a precursor for N-acetylglucosamine (GlcNAc), is a major component of mammalian glycans. The supplementation of GlcN to CHO cells stably-expressing a chimeric heavy-chain monoclonal antibody, EG2-hFc, reduces the complexity of glycans to favour G0 glycoforms, while also negatively impacting cell growth. Although several researchers have examined the supplementation of glucosamine, no clear explanation of its impact on cell growth has been forthcoming. In this work, the glucosamine metabolism is examined. We identified the acetylation of GlcN to produce GlcNAc to be the most likely cause for the negative impact on growth due to the depletion of intracellular acetyl-CoA pools in the cytosol. By supplementing GlcNAc in lieu of GlcN to CHO cells producing EG2-hFc, we achieve the same shift in glycan complexity with marginal impacts on the cell growth and protein production.

Using cognitive task analysis to identify critical decisions in the laparoscopic environment.

OBJECTIVE: The aim of this study was to identify the critical decisions surgeons need to make regarding laparoscopic surgery, the information these decisions are based on, the strategies employed by surgeons to reach their objectives, and the difficulties experienced by novices. BACKGROUND: Laparoscopic training focuses on the development of technical skills. However, successful surgical outcomes are also dependent on appropriate decisions made during surgery, which are influenced by critical cues and the use of appropriate strategies. Novices might not be as adept at cue detection and strategy use. METHOD: Participants were eight attending surgeons. The authors employed task-analytic techniques to identify critical decisions inherent in laparoscopy and the cues, strategies, and novice traps associated with these decisions. RESULTS: The authors used decision requirements tables to organize the data into the key decisions made during the preoperative, operative, and postoperative phases as well as the cues, strategies, and novice traps associated with these decisions. Key decisions identified for the preoperative phase included but were not limited to the decision of performing a laparoscopic versus open surgery, necessity to review the literature, practicing the procedure, and trocar placement. Some key decisions identified for the operative phase included converting to open surgery, performing angiograms, cutting tissue or organs, and reevaluation of the approach. Only one key decision was identified for the postoperative phrase: whether the surgeon's technique needs to be evaluated and revised. CONCLUSION: The laparoscopic environment requires complex decision making, and novices are prone to errors in their decisions. APPLICATION: The information elicited in this study is applicable to laparoscopic training.