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Dr. Homero  Rivas Ii Md image

Dr. Homero Rivas Ii Md

5617 Highway 153 Suite 103
Hixson TN 37343
423 853-3226
Medical School: Other - Unknown
Accepts Medicare: No
Participates In eRX: No
Participates In PQRS: No
Participates In EHR: No
License #: 42493
NPI: 1932399300
Taxonomy Codes:
208100000X 208VP0014X

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Publications

The Influence of Resected Gastric Weight upon Weight Loss after Sleeve Gastrectomy. - The American surgeon
Bariatric surgery is an effective and enduring treatment for obesity. Sleeve gastrectomy (SG) has emerged as an increasingly prevalent surgical intervention. Further investigation is required to determine optimal standardization of SG. Data were collected prospectively for 64 patients who underwent a laparoscopic vertical SG between December 2010 and February 2013 at a single academic institution. Demographic, intraoperative, and postoperative (postop) data were collected for all patients including weighing each resected stomach. The total resected gastric weight varied widely. Preoperatively, patients in the upper tercile for resected gastric weight were more likely to be male (lower 10%, middle 23%, upper 52%, P = 0.006) and had greater initial weights (lower 255.9%, middle 245.1%, upper 280.0%, P = 0.019). The resected gastric weight (g) varied by tercile (mean of all, 131.24 ± 39.8; lower, 93.9 ± 10.9; middle, 127.4 ± 11.7; upper 172.7 ± 37.9, P = 0.000). Patients were followed for 1-year postop with follow-up data for 94 per cent (60/64) of participants. Per cent excess weight loss (EWL) was obtained at three, six, and 12 months postop. At 12 months, there was a trend toward increased per cent EWL in the upper tercile (lower 61.1%, middle 54.1%, upper 90.5%, P = 0.057). In conclusion, while the amount of gastric sleeve resected can vary, this study shows that intraoperative assessment of resected sleeve weight can help evaluate adequacy of resection. Improved 12-month per cent EWL in patients with greater resected tissue demonstrate potentially improved outcomes.
Do adverse childhood experiences affect surgical weight loss outcomes? - Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract
Bariatric surgery is an effective and enduring treatment for obesity; however, variation in weight loss may occur following surgery. Many factors beyond technical considerations may influence postoperative outcomes. A better understanding of the influence of adverse childhood experiences (ACE) on surgical weight loss may improve preoperative care. Demographic and preoperative and postoperative data were prospectively obtained for 223 patients undergoing bariatric surgery. All cases were completed laparoscopically without serious complication. Patients completed the ACE questionnaire, which assesses childhood maltreatment. Patients had an average age of 48 years and 77 % were female. There was a significant reduction from preoperative to 12-month postoperative BMI (45 to 31 kg/m(2), p ≤ 0.01). The average ACE score was 2.9 and these patients were more likely than population norms to have an ACE score ≥4 (35.9 vs. 12.5 %, p < 0.001). There was a positive correlation between the number of preoperative comorbidities and preoperative ACE score (R = 0.112, p = 0.09). Patients with a high ACE score (≥6) vs. patients low ACE scores had a higher postoperative BMI at 6-months (36.9 vs. 33.4 kg/m(2), p = 0.03) and 12-months postoperatively (34.5 vs. 30.5 kg/m(2), p = 0.07). High ACE patients had higher total cholesterol (191 vs. 169 mg/dL, p = 0.02) and LDL cholesterol (116 vs. 94 mg/dL, p = 0.02) than low ACE patients 12-months postoperatively. A high preoperative ACE score decreases weight loss following bariatric surgery and may warrant an increased preoperative counseling.
Mesenteric defect closure in laparoscopic Roux-en-Y gastric bypass: a randomized controlled trial. - Surgical endoscopy
Internal herniation is a potential complication following laparoscopic Roux-en-Y gastric bypass (LRYGB). Previous studies have shown that closure of mesenteric defects after LRYGB may reduce the incidence of internal herniation. However, controversy remains as to whether mesenteric defect closure is necessary to decrease the incidence of internal hernias after LRYGB. This study aims to determine if jejeunal mesenteric defect closure reduces incidence of internal hernias and other complications in patients undergoing LRYGB.105 patients undergoing laparoscopic antecolic RYGB were randomized into two groups: closed mesenteric defect (n = 50) or open mesenteric defect (n = 55). Complication rates were obtained from the medical record. Patients were followed up to 3 years post-operatively. Patients also completed the gastrointestinal quality of life index (GI QoL) pre-operatively and 12 months post-operatively. Outcome measures included: incidence of internal hernias, complications, readmissions, reoperations, GI QoL scores, and percent excess weight loss (%EWL).Pre-operatively, there were no significant differences between the two groups. The closed group had a longer operative time (closed-153 min, open-138 min, p = 0.073). There was one internal hernia in the open group. There was no significant difference at 12 months for decrease in BMI (closed-15.9, open-16.3 kg/m(2), p = 0.288) or %EWL (closed-75.3%, open-69.0%, p = 0.134). There was no significant difference between the groups in incidence of internal hernias and general complications post-operatively. Both groups showed significantly improved GI QoL index scores from baseline to 12 months post-surgery, but there were no significant differences at 12 months between groups in total GI QoL (closed-108, open-112, p = 0.440).In this study, closure or non-closure of the jejeunal mesenteric defect following LRYGB appears to result in equivalent internal hernia and complication rates. High index of suspicion should be maintained whenever internal hernia is expected after LRYGB.
T-cell profile in adipose tissue is associated with insulin resistance and systemic inflammation in humans. - Arteriosclerosis, thrombosis, and vascular biology
The biological mechanisms linking obesity to insulin resistance have not been fully elucidated. We have shown that insulin resistance or glucose intolerance in diet-induced obese mice is related to a shift in the ratio of pro- and anti-inflammatory T cells in adipose tissue. We sought to test the hypothesis that the balance of T-cell phenotypes would be similarly related to insulin resistance in human obesity.Healthy overweight or obese human subjects underwent adipose-tissue biopsies and quantification of insulin-mediated glucose disposal by the modified insulin suppression test. T-cell subsets were quantified by flow cytometry in visceral (VAT) and subcutaneous adipose tissue (SAT). Results showed that CD4 and CD8 T cells infiltrate both depots, with proinflammatory T-helper (Th)-1, Th17, and CD8 T cells, significantly more frequent in VAT as compared with SAT. T-cell profiles in SAT and VAT correlated significantly with one another and with peripheral blood. Th1 frequency in SAT and VAT correlated directly, whereas Th2 frequency in VAT correlated inversely, with plasma high-sensitivity C-reactive protein concentrations. Th2 in both depots and peripheral blood was inversely associated with systemic insulin resistance. Furthermore, Th1 in SAT correlated with plasma interleukin-6. Relative expression of associated cytokines, measured by real-time polymerase chain reaction, reflected flow cytometry results. Most notably, adipose tissue expression of anti-inflammatory interleukin-10 was inversely associated with insulin resistance.CD4 and CD8 T cells populate human adipose tissue and the relative frequency of Th1 and Th2 are highly associated with systemic inflammation and insulin resistance. These findings point to the adaptive immune system as a potential mediator between obesity and insulin resistance or inflammation. Identification of antigenic stimuli in adipose tissue may yield novel targets for treatment of obesity-associated metabolic disease.© 2014 American Heart Association, Inc.
Increasing access to specialty surgical care: application of a new resource allocation model to bariatric surgery. - Annals of surgery
To calculate the public health impact and economic benefit of using ancillary health care professionals for routine postoperative care.The need for specialty surgical care far exceeds its supply, particularly in weight loss surgery. Bariatric surgery is cost-effective and the only effective long-term weight loss strategy for morbidly obese patients. Without clinically appropriate task shifting, surgeons, hospitals, and untreated patients incur a high opportunity cost.Visit schedules, time per visit, and revenues were obtained from bariatric centers of excellence. Case-specific surgeon fees were derived from published Current Procedural Terminology data. The novel Microsoft Excel model was allowed to run until a steady state was evident (status quo). This model was compared with one in which the surgeon participates in follow-up visits beyond 3 months only if there is a complication (task shifting). Changes in operative capacity and national quality-adjusted life years (QALYs) were calculated.In the status quo model, per capita surgical volume capacity equilibrates at 7 surgical procedures per week, with 27% of the surgeon's time dedicated to routine long-term follow-up visits. Task shifting increases operative capacity by 38%, resulting in 143,000 to 882,000 QALYs gained annually. Per surgeon, task shifting achieves an annual increase of 95 to 588 QALYs, $5 million in facility revenue, 48 cases of cure of obstructive sleep apnea, 44 cases of remission of type 2 diabetes mellitus, and 35 cases of cure of hypertension.Optimal resource allocation through task shifting is economically appealing and can achieve dramatic public health benefit by increasing access to specialty surgery.
Single-incision laparoscopic cholecystectomy is associated with improved cosmesis scoring at the cost of significantly higher hernia rates: 1-year results of a prospective randomized, multicenter, single-blinded trial of traditional multiport laparoscopic - Journal of the American College of Surgeons
Minimally invasive techniques have become an integral part of general surgery with recent investigation into single-incision laparoscopic cholecystectomy (SILC). This study presents the final 1-year results of a prospective, randomized, multicenter, single-blinded trial of SILC vs multiport cholecystectomy (4PLC).Patients with biliary colic and documented gallstones or polyps or with biliary dyskinesia were randomized to SILC vs 4PLC. Data measures included operative details, adverse events, and conversion to 4PLC or laparotomy. Patients were followed for 12 months.Two hundred patients underwent randomization to SILC (n = 119) or 4PLC (n = 81). Enrollment ranged from 1 to 50 patients with 4 sites enrolling >25 patients. Total adverse events were not significantly different between groups (36% 4PLC vs 45% SILC; p = 0.24), as were severe adverse events (4% 4PLC vs 10% SILC; p = 0.11). Incision-related adverse events were higher after SILC (11.7% vs 4.9%; p = 0.13), but all of these were listed as mild or moderate. Total hernia rates were 1.2% (1 of 81) in 4PLC patients vs 8.4% (10 of 119) in SILC patients (p = 0.03). At 1-year follow-up, cosmesis scores continued to favor SILC (p < 0.0001).Results of this trial show SILC to be a safe and feasible procedure when compared with 4PLC, with similar total adverse events but with an identified significant increase in hernia formation. Cosmesis scoring and patient preference at 12 months continue to favor SILC, and more than half of the patients were willing to pay more for a single-site surgery over a standard laparoscopic procedure. Additional longer-term population-based studies are needed to clarify if this increased rate of hernia formation as compared with 4PLC will continue to hold true.Copyright © 2013 American College of Surgeons. Published by Elsevier Inc. All rights reserved.
Present and future advanced laparoscopic surgery. - Asian journal of endoscopic surgery
Modern laparoscopy, starting with Kurt Semm's insufflators and the first successful appendectomies, has only been around for approximately 30 years. Since those early successes, the technology has grown from the inception of basic laparoscopy to endoscopic surgery through natural orifices, and it continues to evolve by leaps and bounds with computer-assisted surgery and improved robotics in surgery. Without question, laparoscopy has revolutionized the way we perform standard surgery, especially relative to the techniques that had been used for hundreds of years. Despite the development of multiple novel technologies since the 1980s, very little has changed with regard to basic conceptualizations and practice of laparoscopy. In this review article, we will describe the highlights of recent advanced laparoscopic surgery procedures, their potential applications within the field of surgery, and how these advances may impact and improve future quality and patient outcomes.© 2013 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.
Comparison of robotic and laparoendoscopic single-site surgery systems in a suturing and knot tying task. - Surgical endoscopy
Laparoendoscopic single-site (LESS) surgery has been established for various procedures. Shortcomings of LESS surgery include loss of triangulation, instrument collisions, and poor ergonomics, making advanced laparoscopic tasks especially challenging. We compared a LESS system with a robotic single-site surgery platform in performance of a suturing and knot-tying task under clinically simulated conditions.Each of five volunteer minimally invasive surgeons was tasked with suturing a 5 cm longitudinal enterotomy in porcine small intestine with square knots at either end, using a laparoendoscopic or da Vinci robotic single-site surgery platform, within a 20 min time limit. A saline leak test was then performed. Each surgeon performed the task twice using each system. The time to completion of the task and presence of a leak were noted. Fisher's exact test was used to compare the overall completion rate within the defined time limit, and a Wilcoxon rank test was used to compare the specific times to complete the task. A p value of <0.05 was considered significant.All surgeons were able to complete the task on the first try within 20 min using the robot system; 60% of surgeons were able to complete it after two attempts using the LESS surgery system. Time to completion using the robot system was significantly shorter than the time using the standard LESS system (p < 0.0001). There were no leaks after closure with the robot system; the leak rate following the standard LESS system was 90%.Surgeons demonstrated significantly better suturing and knot-tying capabilities using the robot single-site system compared to a standard LESS system. The robotic system has the potential to expand single-site surgery to more complex tasks.
Consensus statement of the consortium for LESS cholecystectomy. - Surgical endoscopy
Many surgeons attempting Laparo-Endoscopic Single Site (LESS) cholecystectomy have found the operation difficult, which is inconsistent with our experience. This article is an attempt to promote a standardized approach that we feel surgeons with laparoscopic skills can perform safely and efficiently. This is a four-trocar approach consistent with the four incisions utilized in conventional laparoscopic cholecystectomy. After administration of general anesthesia, marcaine is injected at the umbilicus and a 12-mm vertical incision is made through the already existing anatomical scar of the umbilicus. A single four-trocar port is inserted. A 5-mm deflectable-tip laparoscope is placed through the trocar at the 8 o'clock position, a bariatric length rigid grasper is inserted through the trocar at the 4 o'clock position (to grasp the fundus), and a rigid bent grasper is placed through the 10-mm port (to grasp the infundibulum). This arrangement of the instruments promotes minimal internal and external instrument clashing with simultaneous optimization of the operative view. This orientation allows retraction of the gallbladder in a cephalad and lateral direction, development of a window between the gallbladder and the liver which promotes the "critical view" of the cystic duct and artery, and provides triangulation with excellent visualization of the operative field. The operation is concluded with diaphragmatic irrigation of marcaine solution to minimize postoperative pain. Standardization of LESS cholecystectomy will speed adoption, reduce intraoperative complications, and improve the efficiency and safety of the approach.
Intermediate results of a prospective randomized controlled trial of traditional four-port laparoscopic cholecystectomy versus single-incision laparoscopic cholecystectomy. - Surgical endoscopy
Minimally invasive techniques have become an integral part of general surgery, with recent investigation into single-incision laparoscopic cholecystectomy (SILC). This study presents a prospective, randomized, multicenter, single-blind trial of SILC compared with four-port cholecystectomy (4PLC) with the goal of assessing safety, feasibility, and factors predicting outcomes.Patients with biliary colic and documented gallstones or polyps or with biliary dyskinesia were randomized to SILC or 4PLC. Data measures included operative details, adverse events, and conversion to 4PLC or laparotomy. Pain, cosmesis, and quality-of-life scores were documented. Patients were followed for 12 months.Two hundred patients were randomized to SILC (n = 117) or 4PLC (n = 80) (3 patients chose not to participate after randomization). Patients were similar except for body mass index (BMI), which was lower in the SILC patients (28.9 vs. 31.0, p = 0.011). One SILC patient required conversion to 4PLC. Operative time was longer for SILC (57 vs. 45 min, p < 0.0001), but outcomes, including total adverse events, were similar (34% vs. 38%, p = 0.55). Cosmesis scores favored SILC (p < 0.002), but pain scores were lower for 4PLC (1 point difference in 10-point scale, p < 0.028) despite equal analgesia use. Wound complications were greater after SILC (10% vs. 3%, p = 0.047), but hernia recurrence was equivalent for both procedures (1.3% vs. 3.4%, p = 0.65). Univariate analysis showed female gender, SILC, and younger age to be predictors for increased pain scores, while SILC was associated with improved cosmesis scores.In this multicenter randomized controlled trial of SILC versus 4PLC, SILC appears to be safe with a similar biliary complication profile. Pain scores and wound complication rates are higher for SILC; however, cosmesis scores favored SILC. For patients preferring a better cosmetic outcome and willing to accept possible increased postoperative pain, SILC offers a safe alternative to the standard 4PLC. Further follow-up is needed to detail the long-term risk of wound morbidities, including hernia recurrence.

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