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Objective To determine the impact of tumor characteristics and treatment approach on (1) local recurrence, (2) scoliosis development and (3) patient-reported quality of life in children with sarcoma of the chest wall. Summary background data Children with chest wall sarcoma require multimodal therapy including chemotherapy, surgery and/or radiation. Despite aggressive therapy which places them at risk for functional impairment and scoliosis, these patients are also at significant risk for local recurrence. Methods A multi-institutional review of 175 children (median age 13 years) with chest wall sarcoma treated at seventeen Pediatric Surgical Oncology Research Collaborative institutions between 2008-2017 was performed. Patient-reported quality of life was assessed prospectively using PROMIS surveys. Results The most common diagnoses were Ewing sarcoma (67%) and osteosarcoma (9%). Surgical resection was performed in 85% and radiation in 55%. A median of 2 ribs were resected (IQR = 1-3), and number of ribs resected did not correlate with margin status (p = 0.36). Local recurrence occurred in 23% and margin status was the only predictive factor (HR 2.24, p = 0.039). With a median follow-up of 5 years, 13% developed scoliosis (median Cobb angle 26) and 5% required corrective spine surgery. Scoliosis was associated with posterior rib resection (HR 8.43; p = 0.003) and increased number of ribs resected (HR 1.78; p = 0.02). Overall, patient-reported quality of life is not impaired following chest wall tumor resection. Conclusions Local recurrence occurs in one-quarter of children with chest wall sarcoma and is independent of tumor type. Scoliosis occurs in 13% of patients, but patient-reported quality of life is excellent.

Purpose Rapid sequence intubation (RSI) drugs, such as propofol, affect clinical outcomes, but this has not been examined in the pediatric population. This descriptive study compares the outcomes associated with intubation drugs used in pediatric traumatic brain injury (TBI) patients. Methods A retrospective chart review and descriptive analysis of intubated TBI patients, ages 0–17, admitted to Children's Hospital London Health Sciences Centre (LHSC) from January 2006–December 2016 was performed. Results Out of 259 patients intubated, complete data was available for 107 cases. Average injury severity score was 28; 46 were intubated at LHSC, 55 at primary care site, and 6 on scene. Intubation attempts were recorded in 87 of 107 paper charts. First-pass intubation success rate was 88.5%. Propofol (n = 21), midazolam (n = 31), etomidate (n = 13), and ketamine (n = 7) were the most commonly used intubation drugs. Paralytics were used in 50% of patients. Following use of propofol, Pediatric Adjusted Shock Index was increased as a result of worsening hypotension. Mean total hospital length of stay was 21 days with 7.5 days in ICU. Survival was 87%. Conclusion Great variability exists in the use of induction agents and paralytics for RSI. Propofol was commonly used and is potentially associated with poorer clinical outcomes. Type of Study Retrospective. Level of Evidence IV

How individuals in a group lead to collective behavior is a fundamental question across biological systems, from cellular systems, to animal groups, to human organizations. Recent technological advancements have enabled an unprecedented increase in our ability to collect, quantify, and analyze how individual responses lead to group behavior. However, despite a wealth of data demonstrating that collective behavior exists across biological scales, it is difficult to make general statements that apply in different systems. In this perspective, we present a cohesive framework for comparing groups across different levels of biological organization, using an intermediate link of “collective mechanisms” that connects individual responses to group behavior. Using this approach we demonstrate that an effective way of comparing different groups is with an analysis hierarchy that asks complementary questions, including how individuals in a group implement various collective mechanisms, and how these various mechanisms are used to achieve group function. We apply this framework to compare two collective systems—cellular systems and honey bee colonies. Using a case study of a response to a disturbance, we compare and contrast collective mechanisms used in each system. We then discuss how inherent differences in group structure and physical constraints lead to different combinations of collective mechanisms to solve a particular problem. Together, we demonstrate how a hierarchical approach can be used to compare and contrast different systems, lead to new hypotheses in each system, and form a basis for common research questions in collective behavior.

Nearly all animals forage to acquire energy for survival through efficient search and resource harvesting. Patch exploitation is a canonical foraging behaviour, but there is a need for more tractable and understandable mathematical models describing how foragers deal with uncertainty. To provide such a treatment, we develop a normative theory of patch foraging decisions, proposing mechanisms by which foraging behaviours emerge in the face of uncertainty. Our model foragers statistically and sequentially infer patch resource yields using Bayesian updating based on their resource encounter history. A decision to leave a patch is triggered when the certainty of the patch type or the estimated yield of the patch falls below a threshold. The time scale over which uncertainty in resource availability persists strongly impacts behavioural variables like patch residence times and decision rules determining patch departures. When patch depletion is slow, as in habitat selection, departures are characterized by a reduction of uncertainty, suggesting that the forager resides in a low-yielding patch. Uncertainty leads patch-exploiting foragers to overharvest (underharvest) patches with initially low (high) resource yields in comparison with predictions of the marginal value theorem. These results extend optimal foraging theory and motivate a variety of behavioural experiments investigating patch foraging behaviour.

Background To better characterize short-term and long-term outcomes in children with pancreatic tumors treated with pancreaticoduodenectomy (PD). Methods Patients 21 years of age or younger who underwent PD at Pediatric Surgical Oncology Collaborative (PSORC) hospitals between 1990 and 2017 were identified. Demographic, clinical information, and outcomes (operative complications, long-term pancreatic function, recurrence, and survival) were collected. Results Sixty-five patients from 18 institutions with a median age of 13 years (4 months-22 years) and a median (IQR) follow-up of 2.8 (4.3) years were analyzed. Solid pseudopapillary tumor of the pancreas (SPN) was the most common histology. Postoperative complications included pancreatic leak in 14% (n = 9), delayed gastric emptying in 9% (n = 6), marginal ulcer in one patient, and perioperative (30-day) death due to hepatic failure in one patient. Pancreatic insufficiency was observed in 32% (n = 21) of patients, with 23%, 3%, and 6% with exocrine, or endocrine insufficiencies, or both, respectively. Children with SPN and benign neoplasms all survived. Overall, there were 14 (22%) recurrences and 11 deaths (17%). Univariate analysis revealed non-SPN malignant tumor diagnosis, preoperative vascular involvement, intraoperative transfusion requirement, pathologic vascular invasion, positive margins, and need for neoadjuvant chemotherapy as risk factors for recurrence and poor survival. Multivariate analysis only revealed pathologic vascular invasion as a risk factor for recurrence and poor survival. Conclusion This is the largest series of pediatric PD patients. PD is curative for SPN and benign neoplasms. Pancreatic insufficiency is the most common postoperative complication. Outcome is primarily associated with histology.

OBJECTIVE Female medical students and surgical trainees are more likely to lack confidence in their clinical abilities than their male peers despite equal or superior performance. This study aims to examine the role of gender in medical student experience and confidence performing technical skills in surgical clerkship. DESIGN This was a single-center survey study conducted over 2 academic years (2016-2018). Students were surveyed on their experience and confidence performing a set of 9 technical skills during surgical clerkship and to identify skill-specific barriers to learning. SETTING This study was performed at Western University, London, Ontario, Canada. PARTICIPANTS All third-year medical students were invited to participate. RESULTS A total of 253 students participated yielding a survey response rate of 74.0%. Both male and female students reported similar levels of preclerkship interest in a surgical career, enjoyment in performing technical skills, confidence in ability to learn surgical skills and pursuit of available learning opportunities. At the conclusion of their surgical rotations, female students reported less experience and confidence performing technical skills compared to their male colleagues. Female students were more likely to cite an insufficient number of learning opportunities from consultant and resident teachers, time constraints, and lack of confidence as barriers to the achievement of technical proficiency. CONCLUSIONS Female gender was associated with less procedural experience and inferior confidence performing procedural skills. It is important for educators to be aware of this gender disparity and to actively promote equitable learning opportunities for female trainees.

Background: Image-guided percutaneous core needle biopsy (PCNB) is increasingly utilized to diagnose solid tumors. The objective of this study is to determine whether PCNB is adequate for modern biologic characterization of neuroblastoma. Procedure: A multi-institutional retrospective study was performed by the Pediatric Surgical Oncology Research Collaborative on children with neuroblastoma at 12 institutions over a 3-year period. Data collected included demographics, clinical details, biopsy technique, complications, and adequacy of biopsies for cytogenetic markers utilized by the Children's Oncology Group for risk stratification. Results: A total of 243 children were identified with a diagnosis of neuroblastoma: 79 (32.5%) tumor excision at diagnosis, 94 (38.7%) open incisional biopsy (IB), and 70 (28.8%) PCNB. Compared to IB, there was no significant difference in ability to accurately obtain a primary diagnosis by PCNB (95.7% vs 98.9%, P =.314) or determine MYCN copy number (92.4% vs 97.8%, P =.111). The yield for loss of heterozygosity and tumor ploidy was lower with PCNB versus IB (56.1% vs 90.9%, P

Purpose The purpose of this study was to determine whether children with a positive ultrasound (US) for acute appendicitis but a negative clinical picture developed appendicitis requiring definitive management. Methods After obtaining IRB approval, we conducted a retrospective review of patients ≤17years who presented with possible acute appendicitis between April 1st, 2014, and December 31st, 2015. We included patients with a US suggestive of acute appendicitis based on size criteria but without concerning clinical features. Patients were discharged from the emergency department (ED) or admitted for observation. Variables included demographic data, US characteristics, clinical findings, length of follow-up, and appendectomy. Results Of the 31 patients identified, 45% were male and average age was 11.3yrs. On US, the average maximal diameter of the appendix was 6.93mm. The median length of follow-up was 16.8 months, including 10 returns to the ED by 9 patients. Three of these underwent immediate laparoscopic appendectomy, while one had interval appendectomy. There were no cases of perforated appendicitis, and only 2 cases demonstrated pathology consistent with appendicitis. Conclusion These findings demonstrate that it is safe to consider conservative measures such as observation or discharge in children with a positive US for appendicitis based on size criteria but a negative clinical picture. Level of Evidence 4

Hypertrophic pyloric stenosis (HPS) is a common neonatal condition treated with open or laparoscopic pyloromyotomy. 3D-printed organs offer realistic simulations to practice surgical techniques. The purpose of this study was to validate a 3D HPS stomach model and assess model reliability and surgical realism.Medical students, general surgery residents, and adult and pediatric general surgeons were recruited from a single center. Participants were videotaped three times performing a laparoscopic pyloromyotomy using box trainers and 3D-printed stomachs. Attempts were graded independently by three reviewers using GOALS and Task Specific Assessments (TSA). Participants were surveyed using the Index of Agreement of Assertions on Model Accuracy (IAAMA).Participants reported their experience levels as novice (22%), inexperienced (26%), intermediate (19%), and experienced (33%). Interrater reliability was similar for overall average GOALS and TSA scores. There was a significant improvement in GOALS (p0.0001) and TSA scores (p=0.03) between attempts and overall. Participants felt the model accurately simulated a laparoscopic pyloromyotomy (82%) and would be a useful tool for beginners (100%).A 3D-printed stomach model for simulated laparoscopic pyloromyotomy is a useful training tool for learners to improve laparoscopic skills. The GOALS and TSA provide reliable technical skills assessments.II.

The spatio-temporal distribution of individuals within a group (i.e its internal structure) plays a defining role in how individuals interact with their environment, make decisions, and transmit information via social interactions. Group-living organisms across taxa, including many species of fish, birds, ungulates, and insects, use vision as the predominant modality to coordinate their collective behavior. Despite this importance, there have been few quantitative studies examining visual detection capabilities of individuals within groups. We investigate key principles underlying individual, and collective, visual detection of stimuli (which could include cryptic predators, potential food items, etc.) and how this relates to the internal structure of groups. While the individual and collective detection principles are generally applicable, we employ a model experimental system of schooling golden shiner fish (Notemigonus crysoleucas) to relate theory directly to empirical data, using computational reconstruction of the visual fields of all individuals to do so. Our integrative approach allows us to reveal how the external visual information available to each group member depends on the number of individuals in the group, the position within the group, and the location of the external visually-detectable stimulus. We find that in small groups, individuals have detection capability in nearly all directions, while in large groups, occlusion by neighbors causes detection capability to vary with position within the group. We then formulate a simple, and generally applicable, model that captures how visual detection properties emerge due to geometric scaling of the space occupied by the group and occlusion caused by neighbors. We employ these insights to discuss principles that extend beyond our specific system, such as how collective detection depends on individual body shape, and the size and structure of the group.

An extracorporeal (ECA), transumbilical appendectomy has been proposed as a treatment for appendicitis. This study assessed the 30-day perioperative outcomes and cost between ECA and traditional intracorporeal (ICA) techniques for acute uncomplicated appendicitis.IRB approval was obtained for this retrospective cohort study of acute uncomplicated appendicitis in children aged 4 to 17 between April 2014 and April 2017. Patients were grouped based on ICA versus ECA. Operative time, length of stay, and complication rates were recorded.A total of 289 patients were included, and of these 217 underwent ICA, and 72 underwent ECA. Median weight-for-age percentile was the only demographic characteristic different between groups (ECA 50 [0.1-100] vs. ICA 71 [0-100]; p 0.01). Median operative time was significantly shorter in the ECA group (21.0 min [8.0-61.0] vs. 38.0 min [19.0-87.0]; p 0.0001). Length of stay and complication rates were similar between groups. The median per case cost was significantly lower in the ECA group (CAD$ 593.05 range: 499.70-900.81 vs. CAD$ 858.78 range: 490.36-1106.29; p 0.001).Extracorporeal transumbilical laparoscopic appendectomy is associated with shorter operative times and no increased risk of 30-day postoperative complications in children and adolescents. This offers a new operative approach that may reduce hospital cost and resources.III.

BACKGROUND: Optimal management of neutropenic appendicitis (NA) in children undergoing cancer therapy remains undefined. Management strategies include upfront appendectomy or initial nonoperative management. We aimed to characterize the effect of management strategy on complications and length of stay (LOS) and describe implications for chemotherapy delay or alteration. METHODS: Sites from the Pediatric Surgery Oncology Research Collaborative performed a retrospective review of children with NA over a 6-year period. RESULTS: Sixty-six children, with a median age of 11 years (range 1–17), were identified with NA while undergoing cancer treatment. The most common cancer diagnoses were leukemia (62%) and brain tumor (12%). Upfront appendectomy was performed in 41% of patients; the remainder had initial nonoperative management. Rates of abscess or perforation at diagnosis were equivalent in the groups (30% vs 24%; P = .23). Of patients who had initial nonoperative management, 46% (17 of 37) underwent delayed appendectomy during the same hospitalization. Delayed appendectomy was due to failure of initial nonoperative management in 65% (n = 11) and count recovery in 35% (n = 6). Cancer therapy was delayed in 35% (n = 23). Initial nonoperative management was associated with a delay in cancer treatment (46% vs. 22%, P = .05) and longer LOS (29 vs 12 days; P = .01). Patients who had initial nonoperative management and delayed appendectomy had a higher rate of postoperative complications (P CONCLUSIONS: In pediatric patients with NA from oncologic treatment, upfront appendectomy resulted in lower complication rates, reduced LOS, and fewer alterations in chemotherapy regimens compared to initial nonoperative management.

Objective Medical students are expected to achieve proficiency in a prescribed set of technical skills during surgical clerkship. However, available literature indicates students routinely report a lack of confidence and proficiency in these skills. Our study aims to identify barriers to technical skill development encountered by medical students during surgical clerkship with the goal of developing interventions to address these barriers. Design Three hundred and forty two medical students were surveyed about their experience learning and performing technical skills during surgical clerkship. Students reported confidence in skill performance and subjective barriers to achieving competency using forced-choice and free-text responses. Multivariate regression models identified factors independently associated with specific barriers and more frequent technical skills performance. Setting Main and satellite campuses of a Medical Council of Canada accredited Canadian academic medical center. Participants All third-year medical students. Results A total of 253 students (74%) responded to the survey. Following surgical clerkship, the only technical skills participants felt confident performing independently were sterile technique (96%) and basic suturing (52%). Interest in a surgical career, observership experience, gender, and medical campus site were independently associated with the frequency of skill performance. With respect to developing technical proficiency, commonly cited barriers included lack of suitable cases for student participation (35.0%), time constraints (33.4%), and lack of opportunities provided by both consultants (29.1%) and residents (24.7%). Female gender was independently associated with decreased resident instruction, decreased confidence in skill performance, and fewer opportunities to perform requisite skills. Students at satellite campuses reported fewer barriers. Conclusions We identified (1) lack of suitable cases, (2) time constraints, and (3) failure to provide students opportunities as the most common barriers to technical skill proficiency. Female gender increased the perception of barriers, while there were fewer barriers perceived by students at satellite campuses. Skill-specific simulation training and other interventions may improve skill development in medical students given obstacles to developing proficiency in the clinical setting.