Juan C. Cendan

The changing face of surgical education: simulation as the new paradigm.

Surgical simulation has evolved considerably over the past two decades and now plays a major role in training efforts designed to foster the acquisition of new skills and knowledge outside of the clinical environment. Numerous driving forces have fueled this fundamental change in educational methods, including concerns over patient safety and the need to maximize efficiency within the context of limited work hours and clinical exposure. The importance of simulation has been recognized by the major stake-holders in surgical education, and the Residency Review Committee has mandated that all programs implement skills training curricula in 2008. Numerous issues now face educators who must use these novel training methods. It is important that these individuals have a solid understanding of content, development, research, and implementation aspects regarding simulation. This paper highlights presentations about these topics from a panel of experts convened at the 2008 Academic Surgical Congress.

Gastroesophageal reflux after sleeve gastrectomy in morbidly obese patients

BACKGROUNDnGastroesophageal reflux disease (GERD) is highly prevalent in morbidly obese patients and a high body mass index is a risk factor for the development of this co-morbidity. The effect of laparoscopic sleeve gastrectomy (LSG) on GERD is poorly known.nnnMETHODSnWe studied the effect of LSG on GERD in patients with morbid obesity. A retrospective review of 28 consecutive patients undergoing LSG for morbid obesity from September 2008 to September 2010 was performed.nnnRESULTSnA total of 28 patients, 18 women and 10 men, were identified, with a mean age of 42 years (range 18-60). The mean weight and body mass index was 166 kg and 55.5 kg/m2, respectively. The mean percentage of excess weight loss was 40% (range 17-83), with a mean follow-up time of 32 weeks (range 8-92). All patients had a pre- and postoperative upper gastrointestinal radiographic swallow study as a part of their routine care. Of these patients, 18% were noted to have new-onset GERD on their postoperative upper gastrointestinal swallow test after their LSG procedure. Using the GERD score questionnaire, all patients were interviewed to evaluate their reflux symptoms. We had a 64% response rate, with 22% of patients indicating new-onset GERD symptoms despite receiving daily antireflux therapy. All respondents were extremely happy with their surgery and weight loss to date.nnnCONCLUSIONnLSG might increase the prevalence of GERD despite satisfactory weight loss. Additional studies evaluating esophageal manometry and ambulatory 24-hours pH-metry are needed to better evaluate the effect of LSG on gastroesophageal reflux symptoms.

Decreasing morbidity and mortality in 100 consecutive minimally invasive esophagectomies.

IntroductionEsophagectomy is a complex invasive procedure that requires exploration of multiple body cavities for removal and subsequent restoration of gastrointestinal continuity. In many institutions, esophagectomy morbidity and mortality rates remain high despite improvement of intensive care treatment. We reviewed our minimally invasive esophagectomy (MIE) experience of a consecutive series of 100 patients to analyze trends in morbidity and mortality as we transitioned from open to MIE.MethodsA total of 105 consecutive patients who underwent operative exploration for esophagectomy from August 2007 to January 2011 were reviewed. The preoperative evaluation, operative technique, and postoperative care of these cases were evaluated and analyzed for 100 patients who have had a MIE and compared with 32 open esophagectomies 2xa0years prior.ResultsDuring the time frame of the study, 105 patients underwent an exploration for attempted esophagectomy. Resection was completed in 100 patients and was done for malignant disease in 95 patients and benign disease in 5 patients.xa0There was one in hospital mortalityxa0due to a pulmonary embolism. There was no significant difference in postoperative complications consisting of transient left recurrent nerve injury (7 vs. 12.5%) or pneumonia (9 vs. 15.6%) in those who underwent MIE compared with open resection. However, wound infections were significantly less in patients who underwent MIE compared with open esophagectomy (1 vs. 12.5%, respectively, pxa0=xa00.01). Anastomotic leak (4 vs. 12.5%, pxa0=xa00.05) also was lower in those who underwent MIE. Median length of stay (LOS) was significantly less in patients who underwent MIE compared with open esophagectomy (7.5 vs. 14xa0days, pxa0<xa00.05).xa0Finally, there was a trend toward improvement in median LOS in the 30 patients who underwent MIE during the most recent time period compared with the initial 17 patients who underwent MIE (7.5 vs. 10xa0days, pxa0=xa00.05)ConclusionsOur results support the continued safe use of esophagectomy for selected esophageal diseases, including malignancy. Morbidity, especially wound infection, anastomotic leak, and length of stay is decreasing with the incorporation of minimally invasive techniques.

Differences in outcome between obese and nonobese patients following severe blunt trauma are not consistent with an early inflammatory genomic response.

Objectives:Obesity has been demonstrated to alter a number of acute and chronic medical conditions. The effect of obesity on severely injured patients, however, remains incompletely defined. We sought to unravel potential physiologic and genomic alterations induced by obesity in severely injured blunt trauma patients. Design:A retrospective review of clinical and genomic information contained in the Inflammation and the Host Response to Injury multicenter trauma-related database examining the relationship between body mass index and the early genomic response from peripheral blood leukocytes to patient outcome following severe blunt trauma was performed. Setting:Multicenter collaboration between university-based academic trauma centers. Patients:Severely injured blunt trauma patients enrolled in the database. Interventions:None. Measurements and Main Results:Univariate analysis of 455 severely injured trauma patients using the National Institutes of Health/World Health Organization body mass index classification system revealed significant increases in morbidity, including longer intensive care unit stays and a greater number of ventilator days, cardiac arrests, episodes of acute renal failure, and patients developing multiple organ failure. Regression modeling identified body mass index class as being independently associated with adverse outcomes and increased morbidity but an inverse relationship with mortality in patients who suffered severe blunt traumatic injury. Initial leukocyte genomic expression patterns between 163 patients in the four different body mass index groupings did not differ; however, analysis of gene differences between body mass index classes occurring over time demonstrated significant changes in 513 probe sets with significant pathway differences being related to cellular metabolism. Conclusions:Increasing body mass index is associated with increased morbidity following severe blunt trauma. The initial blood leukocyte inflammatory response to blunt trauma does not appear to differ significantly between patients despite increasing body mass index. Resolution of the inflammatory response may differ between patients on the basis of body mass index; however, additional work is needed to clarify the potential causality of this finding.

Technique of Minimally Invasive Ivor Lewis Esophagogastrectomy with Intrathoracic Stapled Side-to-Side Anastomosis

ObjectiveAn intrathoracic linear stapled side-to-side anastomosis for gastroesophageal junction malignancy is feasible, results in low leak rates and less stenosis.DesignRetrospective case series.SettingUniversity tertiary care center.PatientsBetween March 2008 and January 2009, six patients with gastroesophageal junction malignancy undergoing minimally invasive esophagectomy with an intrathoracic linear stapled side-to-side anastomosis were identified and their clinicopathological data analyzed.Main Outcome MeasuresTechnique of a 6-cm side-to-side stapled intrathoracic esophagogastric anastomosis.ResultsSix patients underwent a minimally invasive esophagectomy with a side-to-side stapled intrathoracic esophagogastric anastomosis. Median age was 61.5xa0years. All patients had gastroesophageal junction adenocarcinoma and completed neoadjuvant chemoradiation therapy. The median operative time was 360xa0min. No patient received a blood transfusion. The 30-day mortality was 0. The median length of hospital stay was 8xa0days. The median number of nodes harvested was 18. At a median follow-up of 9xa0months, all patients were alive. There have been no anastomotic strictures to date.ConclusionA 6-cm side-to-side stapled intrathoracic esophagogastric anastomosis is feasible and is associated with a low anastomotic leak rate.

Minimally Invasive Esophagectomy is Safe and Effective Following Neoadjuvant Chemoradiation Therapy

BackgroundMinimally invasive esophagectomy (MIE) is technically demanding, and implementation has been hindered by a steep learning curve. Despite widespread concern about the successful performance of this procedure following neoadjuvant chemoradiotherapy (NACR) treatment, we hypothesized that safe and effective MIE could be performed in this setting.Materials and MethodsWe reviewed our prospective database of patients undergoing MIE for esophageal cancer at our institution between January 2008 and February 2010. We analyzed the association of NACR on perioperative outcomes and compared them with those patients undergoing MIE without NACR. NACR was used in ≥T2 or N+ tumors.ResultsA total of 61 consecutive patients underwent a planned MIE. A complete MIE or hybrid procedure was performed in 58 patients (95%), while 3 patients were unresectable. Median age was 67xa0years (range 38–85). Anastomoses were performed in the cervical region in 47 patients (81%) while 11 patients had an anastomosis in the right chest. Serious complications included: 3 cervical anastomotic leaks (5%), 2 thoracic duct leaks (4%), 12 pneumonias (21%), 10 atrial fibrillations (18%), and 1 death in a patient not undergoing NACR. NACR was used in 41 patients. There was no significant difference in estimated blood loss (EBL), complications, or negative pathologic margins in patients undergoing NACR with MIE vs. MIE alone (Pxa0=xa0NS). Median number of lymph nodes excised and PostOp LOS was 15 and 11 in patients undergoing NACR compared with 13 and 9 in those undergoing MIE alone (Pxa0=xa0NS).ConclusionMIE is safe following NACR. Excellent results can be achieved with this operation in patients with advanced tumors.

High score!: motivation strategies for user participation in virtual human development

Conversational modeling requires an extended time commitment, and the difficulty associated with capturing the wide range of conversational stimuli necessitates extended user participation. We propose the use of leaderboards, narratives and deadlines as motivation strategies to persuade user participation in the conversational modeling for virtual humans. We evaluate the applicability of leaderboards, narratives and deadlines through a user study conducted with medical students (n=20) for modeling the conversational corpus of a virtual patient character. Leaderboards, narratives and deadlines were observed to be effective in improving user participation. Incorporating these strategies had the additional effect of making user responses less reflective of real world conversations.

Traditional resuscitative practices fail to resolve metabolic acidosis in morbidly obese patients after severe blunt trauma.

BACKGROUNDnObesity is a risk factor for postinjury complications; in particular, obese patients develop multiple organ failure (MOF) at a greater rate than do normal weight counterparts. Evaluation of differences in resuscitative practices altered by body mass index (BMI) might provide an explanation for the increased risk of MOF seen in these high-risk patients.nnnMETHODSnWe used prospectively collected multicenter data to retrospectively compare patients grouped by BMI with regard to resuscitation volumes and traditional end points during the first 48 hours after injury. Marshall MOF score was used as the primary outcome measure.nnnRESULTSnOne thousand sixty-six patients were analyzed, with 877 meeting inclusion and exclusion criteria. All patients received similar volumes of resuscitation per kilogram lean and ideal body weight. Morbidly obese patients attained greater central venous pressures but otherwise differed little in attainment of standard cardiovascular end points. Despite this, morbidly obese patients resolved base deficit more slowly and remained in metabolic acidosis for 48 hours postinjury. Morbidly obese patients with persistent metabolic acidosis developed MOF at a significantly greater rate than did normal weight patients with or without persistent metabolic acidosis.nnnCONCLUSIONSnMorbidly obese trauma patients show prolonged metabolic acidosis despite receiving similar volumes and attaining similar end points of resuscitation when compared with patients in other BMI groups. Inadequate resuscitation based on inaccurate end points and metabolic disturbances associated with increased BMI are likely responsible; identification of the etiology, sources, and consequences of this acidosis may provide further insight into the susceptibility of the morbidly obese patient to develop postinjury organ failure.

Increasedl-arginine transport in a nitric oxide-producing metastatic colon cancer cell line

AbstractBackground: Little is known about amino acid transport in human neoplastic cells. We previously characterizedl-arginine transport in the primary human colon cancer cell line, SW480, and found it is principally mediated by the sodium-independent system y+. In this study, we characterizedl-arginine transport in the metastatic cell line, SW620, and compared it with that in the primary cell line, SW480.nMethods: Transport of3H-l-arginine in cell monolayers was analyzed in the presence and absence of sodium. Kinetic studies were performed over a range ofl-arginine concentrations to determine transporter affinity (Km) and maximal transport velocity (Vmax). Transport was further characterized through blockade with known amino acids. In addition, the effect of cell age (i.e., time in culture) on arginine transport was examined at 2 and 9 days after seeding. Cellular proliferation was asssessed by using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay.nResults:l-Arginine uptake was primarily sodium independent in the SW620 cell line. Kinetic and amino acid-inhibition studies revealed a single high-affinity, sodium-independentl-arginine transporter (Vmax=1286.3 ± 158.3 pmol/mg protein/30 s; Km=46.8 ± 4.2 µM). Sodium-independent transport was blocked by system y+ substratesl-homoarginine,l-ornithine andl-lysine. Sodium-dependent uptake occurs through a single transporter with system BO,+ characteristics (Km=16.15 ± 2.1 µM; Vmax=329.94 ± 29.7 pmol/mg protein/30 s). Arginine transport increased with time in culture with day 2 cells transport velocity =241.7 ± 33.6 pmol/mg protein/30s, whereas day 9 cells transport velocity =377 ± 15.4 pmol/mg protein/30 s (p<0.01). Cellular-proliferation studies revealed a doubling time of 3.2 days for SW620 and 5.4 days for SW480 (p<0.05).nConclusions:l-Arginine transport in these neoplastic cell lines occurs primarily through sodium-independent, high-affinity system y+. Vmax was increased 180% in the metastatic variant (SW620), suggesting upregulation of the y+ transporter. The increased y+ activity may be a mechanism to provide continuous substrate for tumor growth.

Utilization of Intensive Care Resources in Bariatric Surgery

Background: Obese patients occasionally require either elective or emergency critical care services following bariatric surgery. We describe this subgroup of patients. Methods: From July 1, 1991 to July 31, 2004, we performed 1,279 bariatric operations; 241 (19%) required admission to the surgical critical care service. We retrospectively reviewed medical records for gender, body mass index (BMI), age, whether the operation was initial or revisional, and whether critical care admission was elective or emergent. 3 complication clusters (thromboembolic, pulmonary, and anastomotic) were identified using discharge ICD-9 codes. The costs and length of stay of these subpopulations was calculated. Results: Patients were on average 46 ± 10 years old, with BMI 59 ± 13. Critical care admission was emergent in 52.7% (n=127) of cases. Revisional cases did not differ from the initial cases in BMI (56.4 vs 59.2, P=0.42) and they were no more likely to require emergent critical care admission than initial cases (P=0.16). Revisional cases were hospitalized longer (27.2 ± 25.6 vs 12.5 ± 18.7 days, P =0.003); had higher total hospital costs (US