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Dive into the research topics where Evan S. Ong is active.

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Featured researches published by Evan S. Ong.


American Journal of Surgery | 2012

Effect of epidural analgesia on postoperative complications following pancreaticoduodenectomy

Albert Amini; Asad E. Patanwala; Felipe B. Maegawa; Grant H. Skrepnek; Tun Jie; Rainer W. G. Gruessner; Evan S. Ong

BACKGROUND The purpose of this study was to evaluate the effect of epidural analgesia use on postoperative complications in patients undergoing pancreaticoduodenectomy. METHODS This retrospective cohort study used the 2009 Nationwide Inpatient Sample from the Agency for Healthcare Research and Quality. Patients who underwent pancreaticoduodenectomy were grouped on the basis of whether they received epidural analgesia. The effect of epidural use on the composite end point of major complications including death was investigated using a generalized linear model. RESULTS Overall, 8,610 cases of pancreaticoduodenectomy occurred within the United States in 2009, and 11.0% of these patients received epidural analgesia. After controlling for various potential confounders, results of the multivariate regression indicated that epidural analgesia use was associated with lower odds of composite complications including death (odds ratio, .61; 95% confidence interval, .37-.99; P = .044). CONCLUSIONS In patients who underwent pancreaticoduodenectomy, epidural analgesia was associated with significantly lower postoperative composite complications.


Surgical Endoscopy and Other Interventional Techniques | 2011

Intensive laparoscopic training course for surgical residents: program description, initial results, and requirements

Hannah Zimmerman; Rifat Latifi; Behrooz Dehdashti; Evan S. Ong; Tun Jie; Carlos Galvani; Amy Waer; Julie Wynne; David E. Biffar; Rainer W. G. Gruessner

IntroductionThe Department of Surgery at the University of Arizona has created an intensive laparoscopic training course for surgical residents featuring a combined simulation laboratory and live swine model. We herein report the essential components to design and implement a rigorous training course for developing laparoscopic skills in surgical residents.Materials and methodsAt our institution, we developed a week-long pilot intensive laparoscopic training course. Six surgical residents (ranging from interns to chief residents) participate in the structured, multimodality course, without any clinical responsibilities. It consists of didactic instruction, laboratory training, practice in the simulation laboratory, and performance (under the direction of attending laparoscopic surgeons) of surgical procedures on pigs. The pigs are anesthetized and attended by veterinarians and technicians, and then euthanized at the end of each day. Three teams of two different training-level residents are paired. Daily briefing, debriefing, and analysis are performed at the close of each session. A written paper survey is completed at the end of the course.ResultsThis report describes the results of first 36 surgical residents trained in six courses. Preliminary data reveal that all 36 now feel more comfortable handling laparoscopic instruments and positioning trocars; they now perform laparoscopic surgery with greater confidence and favor having the course as part of their educational curriculum.ConclusionA multimodality intensive laparoscopic training course should become a standard requirement for surgical residents, enabling them to acquire basic and advanced laparoscopic skills on a routine basis.


International Journal of Radiation Oncology Biology Physics | 2011

Feasibility of Helical Tomotherapy in Stereotactic Body Radiation Therapy for Centrally Located Early Stage Non‒Small-Cell Lung Cancer or Lung Metastases

Alexander Chi; Si Young Jang; James S. Welsh; Nam P. Nguyen; Evan S. Ong; Lisa S. Gobar; Ritsuko Komaki

PURPOSE To investigate the ability of helical tomotherapy (HT) to spare critical organs immediately adjacent to the tumor target in stereotactic body radiation therapy (SBRT) for centrally located lung lesions. METHODS AND MATERIALS HT SBRT plans for 10 patients with centrally located lesions or lesions immediately adjacent to a critical structure were generated. A total of 70 Gy in 10 fractions was prescribed to the planning target volume (PTV) to satisfy a target volume coverage of ≥95% PTV receiving 70 Gy and an established set of dose constraints for the organs at risk (OARs). Quality assurance (QA) of the HT plans was performed with both ion chamber and film measurements. RESULTS The PTV coverage criteria was met with 95% of the PTV receiving 70.68 ± 0.33 Gy for all cases even though the OARs immediately adjacent to the PTV ranged from 0.38 to 0.85 cm away. The mean lung dose (MLD), and V(20) were 7.15 ± 1.44 Gy, and 11.93 ± 3.24 % for the total lung, respectively. The dose parameters of MLD, V(5), V(10), and V(20) for the contralateral lung were significantly lower than those for the ipsilateral lung (p < 0.05). An average dose fall off from the PTV periphery to the edge of the immediately adjacent OAR was 47.6% over an average distance of 4.87 mm. Comparison of calculated and measured doses with the ion chamber showed an average of 1.85% point dose error, whereas an average mean gamma and the area with a gamma larger than 1 of 0.20 and 0.94% were observed, respectively. CONCLUSION HT allows the sparing of critical structures immediately adjacent to the tumor target, thus making SBRT for these centrally located lesions feasible.


Journal of The American College of Surgeons | 2011

Disparities in Treatment and Survival of White and Native American Patients with Colorectal Cancer: A SEER Analysis

Cristina V. Cueto; Sean Szeja; Betsy C. Wertheim; Evan S. Ong; Vassiliki L. Tsikitis

BACKGROUND Minority groups with colorectal cancer have not experienced the decline in incidence and mortality that has been reported in whites. We sought to determine whether differences exist in treatment and survival between white and Native American patients with colorectal cancer because little has been written about this specific minority group. STUDY DESIGN The Surveillance Epidemiology and End Results (SEER) database for colorectal cancer was used to compare treatment and survival in whites (colon, n = 137,949; rectum, n = 46,843) and Native Americans (colon, n = 872; rectum, n = 316). Cox proportional hazards models were used to compare cancer-specific survival in Native Americans with whites, adjusted for stage, sex, age and year of diagnosis, socioeconomic status, and treatment. RESULTS Native Americans presented at younger ages than whites for both colon and rectal cancer (p < 0.001). They were diagnosed at more advanced stages of disease than whites for only colon cancer. No significant differences were detected in the proportion of patients recommended for surgery between the two groups, for either cancer at any stage (all p > 0.05). Native Americans with rectal cancer were more likely to receive radiation than whites (p < 0.001), but they received less sphincter-preserving surgery (60.0% vs 65.4%; p = 0.045). Native Americans with colon cancer fared significantly worse than whites (hazard ratio = 1.20; 95% CI = 1.08 to 1.34), but there is no difference in cancer-free survival between races for rectal cancer. CONCLUSIONS Compared with whites, Native Americans with colon cancer have worse cancer-specific survival.


Surgical Clinics of North America | 2014

Gallstone Pancreatitis: A Review

Daniel Cucher; Narong Kulvatunyou; Donald J. Green; Tun Jie; Evan S. Ong

Gallstone disease is the most common cause of acute pancreatitis in the Western world. In most cases, gallstone pancreatitis is a mild and self-limiting disease, and patients may proceed without complications to cholecystectomy to prevent future recurrence. Severe disease occurs in about 20% of cases and is associated with significant mortality; meticulous management is critical. A thorough understanding of the disease process, diagnosis, severity stratification, and principles of management is essential to the appropriate care of patients presenting with this disease. This article reviews these topics with a focus on surgical management, including appropriate timing and choice of interventions.


World Journal of Gastrointestinal Surgery | 2012

Cytoreductive surgery and hyperthermic intraperitoneal chemoperfusion: The University of Arizona early experience

Ioannis T Konstantinidis; Christine Young; Vassiliki L. Tsikitis; Ellyn Lee; Tun Jie; Evan S. Ong

AIM To evaluate the safety and effectiveness of our new cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemoperfusion (HIPEC) program. METHODS Retrospective review of patients with gastrointestinal malignancies who were suitable candidates for CRS and HIPEC between 12/1/2009 and 10/1/2010. All clinicopathologic data were reviewed with a special focus on the surgical outcome and the postoperative morbidity and mortality. RESULTS Fourteen patients were identified. Median age was 64 years; seven were female. The primary tumors were: colonic (29%), appendiceal (36%), peritoneal mesothelioma (14%), gastric (7%), adenocarcinoma of unknown primary (7%), and gastrointestinal stromal tumor (7%). Eleven patients (79%) received CRS/HIPEC, three for palliation. Three patients that did not undergo CRS/HIPEC had an average peritoneal cancer index (PCI) of 25. The eight patients that underwent curative CRS/HIPEC had an average PCI of 10 and a completeness of cytoreduction score of 0 (87.5%) or 1 (12.5%). Postoperative morbidity was 36%; the worst adverse event was Grade 3 ileus. Mortality rate was 0%. CONCLUSION CRS with HIPEC is safe and feasible at tertiary institutions with fledgling programs. PCI is an accurate predictor of surgical outcomes.


Journal of the Pancreas | 2013

Recognition of Complications After Pancreaticoduodenectomy for Cancer Determines Inpatient Mortality

Evan S. Glazer; Albert Amini; Tun Jie; Rainer W. G. Gruessner; Robert S. Krouse; Evan S. Ong

CONTEXT While perioperative mortality after pancreaticoduodenectomy is decreasing, key factors remain to be elucidated. OBJECTIVE The purpose of this study was to investigate inpatient mortality after pancreaticoduodenectomy in the Nationwide Inpatient Sample (NIS), a representative inpatient database in the USA. METHODS Patient discharge data (diagnostic and procedure codes) and hospital characteristics were investigated for years 2009 and 2010. The inclusion criteria were a procedure code for pancreaticoduodenectomy, elective procedure, and a pancreatic or peripancreatic cancer diagnosis. Chi-square test determined statistical significance. A logistic regression model for mortality was created from significant variables. RESULTS Two-thousand and 958 patients were identified with an average age of 65±12 years; 53% were male. The mean length of stay was 15±12 days with a mortality of 4% and a complication rate of 57%. Eighty-six percent of pancreaticoduodenectomy occurred in teaching hospitals. Pancreaticoduodenectomy performed in teaching hospitals in the first half of the academic year were associated with higher mortality than in the latter half (5.5% vs. 3.4%, P=0.005). On logistic regression analysis, non-surgical complications are the largest predictor of death (P<0.001) while operations in the latter half of the academic year are associated with decreased mortality (P<0.01). CONCLUSIONS The timing of pancreaticoduodenectomy for cancer remained more predictive of mortality than age or length of stay; only complications were more predictive of death than time of year. This suggests that there remains a clinically and statistically significant learning curve for trainees in identifying complications; further study is needed to prove that identification of complications leads to a decrease in mortality rate by taking corrective actions.


Jsls-journal of The Society of Laparoendoscopic Surgeons | 2011

Large subcapsular liver hematoma following single-incision laparoscopic cholecystectomy.

Adam J. Hansen; Julie Augenstein; Evan S. Ong

Single incision laparoscopic cholecystectomy may pose significant risks that warrant operative caution. The authors suggest that single incision laparoscopic surgery be compared to the “gold-standard” laparoscopic procedure to further elucidate benefits and complications of this novel technique.


IEEE Sensors Journal | 2011

High-Transmission-Efficiency and Side-Viewing Micro OIDRS Probe for Fast and Minimally Invasive Tumor Margin Detection

Alejandro Garcia-Uribe; Cheng Chung Chang; Murat Kaya Yapici; Jun Zou; Bhaskar Banerjee; John Kuczynski; Evan S. Ong; Erin S. Marner; Lihong V. Wang

The determination of a cancer free margin I organ is a difficult and time consuming process, with an unmet need for rapid determination of tumor margin at surgery. In this paper, we report the design, fabrication, and testing of a novel miniaturized optical sensor probe with “side-viewing” capability. Its unprecedented small size, unique “side-viewing” capability, and high optical transmission efficiency enable the agile maneuvering and efficient data collection even in the narrow cavities inside the human body. The sensor probe consists of four micromachined substrates with optical fibers for oblique light incidence and collection of spatially resolved diffuse reflectance from the contacted tissues. The optical sensor probe has been used to conduct the oblique incidence diffuse reflectance spectroscopy (OIDRS) on a human pancreatic specimen. Based on the measurement results, the margin of the malignant tumor has been successfully determined optically, which matches well with the histological results.


Blood Coagulation & Fibrinolysis | 2014

Tissue-type plasminogen activator-induced fibrinolysis is enhanced in patients with breast, lung, pancreas and colon cancer:

Vance G. Nielsen; Ryan W. Matika; Michele Ley; Amy Waer; Farid Gharagozloo; Samuel Kim; Valentine N. Nfonsam; Evan S. Ong; Tun Jie; James Warneke; Evangelina B. Steinbrenner

Although cancer-mediated changes in hemostatic proteins unquestionably promote hypercoagulation, the effects of neoplasia on fibrinolysis in the circulation are less well defined. The goals of the present investigation were to determine if plasma obtained from patients with breast, lung, pancreas and colon cancer was less or more susceptible to lysis by tissue-type plasminogen activator (tPA) compared to plasma obtained from normal individuals. Archived plasma obtained from patients with breast (n = 18), colon/pancreas (n = 27) or lung (n = 19) was compared to normal individual plasma (n = 30) using a thrombelastographic assay that assessed fibrinolytic vulnerability to exogenously added tPA. Plasma samples were activated with tissue factor/celite, had tPA added, and had data collected until clot lysis occurred. Additional, similar samples had potato carboxypeptidase inhibitor added to assess the role played by thrombin-activatable fibrinolysis inhibitor in cancer-modulated fibrinolysis. Rather than inflicting a hypofibrinolytic state, the three groups of cancers demonstrated increased vulnerability to tPA (e.g. decreased time to lysis, increased speed of lysis, decreased clot lysis time). However, hypercoagulation manifested as increased speed of clot formation and strength compensated for enhanced fibrinolytic vulnerability, resulting in a clot residence time that was not different from normal individual thrombi. In sum, enhanced hypercoagulability associated with cancer was in part diminished by enhanced fibrinolytic vulnerability to tPA.

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Tun Jie

University of Arizona

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Amy Waer

University of Arizona

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Alexander Chi

West Virginia University

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Rainer W. G. Gruessner

State University of New York Upstate Medical University

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