Sergio Huerta

Male Gender is a Predictor of Morbidity and Age a Predictor of Mortality for Patients Undergoing Gastric Bypass Surgery

PurposeTo determine preoperative risk factors predictive of adverse outcomes after gastric bypass surgery. Summary Background DataGastric bypass results in sustained weight loss for seriously obese patients, but perioperative complications can be formidable. Preoperative risk assessment is important to establish the risk-benefit ratio for patients undergoing these operations. MethodsData for 10 risk factors predictive of adverse outcomes were collected on 1,067 consecutive patients undergoing gastric bypass surgery at the UCLA Medical Center from December 1993 until June 2000. Univariate analyses were performed for individual risk factors to determine their potential significance as predictors for complications. All 10 risk factors were entered into a logistic regression model to determine their significance as predictors for complications. Sensitivity analysis was performed. ResultsUnivariate analysis revealed that male gender and weight were predictive of severe life-threatening adverse outcomes. Multistep logistic regression yielded only male gender as a risk factor. Male patients were heavier than female patients on entry to the study, accounting for weight as a potential risk factor. Patients older than 55 years had a threefold higher mortality from surgery than younger patients, although the complication rate, 5.8%, was the same in both groups. Sensitivity analysis demonstrated that the risk for severe life-threatening adverse outcomes in women increased from 4% for a 200-lb female patient to 7.5% for a 600-lb patient. The risk increased from 7% for a 200-lb male patient to 13% for a 600-lb patient. ConclusionsLarge male patients are at greater risk for severe life-threatening complications than smaller and/or female patients. Risk factors thought to be predictive of adverse outcomes, such as a history of smoking or diabetes, proved not to be significant in this analysis. Older patients had the same complication rate but a threefold higher mortality, suggesting that they lack the reserve to recover from complications when they occur.

Evaluating an Evidence-Based Bundle for Preventing Surgical Site Infection: A Randomized Trial

OBJECTIVE To determine if an evidence-based practice bundle would result in a significantly lower rate of surgical site infections (SSIs) when compared with standard practice. DESIGN Single-institution, randomized controlled trial with blinded assessment of main outcome. The trial opened in April 2007 and was closed in January 2010. SETTING Veterans Administration teaching hospital. PATIENTS Patients who required elective transabdominal colorectal surgery were eligible. A total of 241 subjects were approached, 211 subjects were randomly allocated to 1 of 2 interventions, and 197 were included in an intention-to-treat analysis. INTERVENTIONS Subjects received either a combination of 5 evidenced-based practices (extended arm) or were treated according to our current practice (standard arm). The interventions in the extended arm included (1) omission of mechanical bowel preparation; (2) preoperative and intraoperative warming; (3) supplemental oxygen during and immediately after surgery; (4) intraoperative intravenous fluid restriction; and (5) use of a surgical wound protector. MAIN OUTCOME MEASURE Overall SSI rate at 30 days assessed by blinded infection control coordinators using standardized definitions. RESULTS The overall rate of SSI was 45% in the extended arm of the study and 24% in the standard arm (P = .003). Most of the increased number of infections in the extended arm were superficial incisional SSIs (36% extended arm vs 19% standard arm; P = .004). Multivariate analysis suggested that allocation to the extended arm of the trial conferred a 2.49-fold risk (95% confidence interval, 1.36-4.56; P = .003) independent of other factors traditionally associated with SSI. CONCLUSIONS An evidence-based intervention bundle did not reduce SSIs. The bundling of interventions, even when the constituent interventions have been individually tested, does not have a predictable effect on outcome. Formal testing of bundled approaches should occur prior to implementation.

Safety and efficacy of postoperative continuous positive airway pressure to prevent pulmonary complications after Roux-en-Y gastric bypass.

Continuous positive airway pressure (CPAP) is used to prevent apneic arrest and/or hypoxia in patients suffering from obstructive sleep apnea. This modality has not been universally accepted for patients following upper gastrointestinal surgery because of concerns that pressurized air will inflate the stomach and proximal intestine, resulting in anastomotic disruption. This study was performed to assess the safety and efficacy of postoperative CPAP for patients undergoing a gastrojejunostomy as part of a Roux-en-Y gastric bypass (RYGB) procedure. A total of 1067 patients (837 women [78%] and 230 men [22%]) were prospectively evaluated for the risk of developing anastomotic leaks and pulmonary complications after the RYGB procedure. Of the 1067 patients undergoing gastric bypass, 420 had obstructive sleep apnea and 159 were dependent on CPAP. There were 15 major anastomotic leaks, two of which occurred in CPAP-treated patients. Contingency table analysis demonstrated that there was no correlation between CPAP utilization and the incidence of major anastomotic leakage (P = 0.6). Notably, no episodes of pneumonia were diagnosed in either group. Despite the theoretical risk of anastomotic injury from pressurized air delivered by CPAP, no anastomotic leaks occurred that were attributable to CPAP. There were no pulmonary complications in a patient population that is at risk for developing them postoperatively. CPAP is a useful modality for treating hypoventilation after RYGB without increasing the risk of developing postoperative anastomotic leaks.

Surgical Bypass Versus Endoscopic Stenting for Malignant Gastroduodenal Obstruction: A Decision Analysis

The treatment options for palliating malignant gastroduodenal obstruction include open gastrojejunostomy (OGJ), laparoscopic gastrojejunostomy (LGJ), and endoscopic stenting (ES). The aim of this study was to compare the clinical outcomes and costs among ES, OGJ, and LGJ in patients who present with gastroduodenal obstruction from advanced upper gastrointestinal tract cancer. We designed a model for patients with malignant gastroduodenal obstruction. We analyzed success rates, complication rates and costs of the three treatment modalities: ES, OGJ, and LGJ. Baseline outcomes and costs were based on published reports. Success was defined as no major procedure-related and long-term complications over a 1-month period. Failure of therapy was defined as recurrent symptoms or death due to a procedural complication. Sensitivity analyses and cost-effectiveness analyses for the various strategies were performed. ES resulted in the lowest mortality rate and the lowest cost of the three treatment options analyzed. Mortality in the OGJ group was 2.1 times that in the ES cohort and 1.8 times that in the LGJ cohort. Sensitivity analyses confirmed ES as the dominant strategy. In conclusion, ES is the preferred treatment for palliation of duodenal obstruction due to advanced upper gastrointestinal tract cancer.

Reassessing the Need for Prophylactic Surgery in Patients With Porcelain Gallbladder: Case Series and Systematic Review of the Literature

OBJECTIVE To evaluate the risk of gallbladder cancer (GBC) in patients with a porcelain gallbladder (PGB). DESIGN Retrospective analysis of our institutional experience and a systematic review of the literature. SETTING Academic teaching facility, Parkland Memorial Hospital, and the Dallas Veterans Affairs Medical Center (all in Dallas, Texas). PATIENTS Medical records of 1200 cholecystectomies performed between 2008 and 2009 at Parkland Memorial Hospital, The University of Texas Southwestern Medical Center, and the Dallas Veterans Affairs Medical Center were reviewed. Patients with radiologic or histologic evidence of PGB or GBC were included. MAIN OUTCOME MEASURES The risk of GBC in patients with a PGB was assessed by contingency table analysis. RESULTS We identified 13 patients with a PGB among 1200 cholecystectomies (1.1%). Most of these patients had concomitant gallstones (n = 9). None of the patients with a PGB had evidence of carcinoma. We also reviewed the histologic analysis results of 35 cases of GBC operated on between 1997 and 2009; none of these had gallbladder wall calcifications. Most patients underwent a laparoscopic cholecystectomy without any postoperative complications. We reviewed 7 published series that included 60,665 cholecystectomies. The overall incidence of PGB was 0.2%, and GBC occurred in 15% of the PGB cases. Most cases of GBC occurring in PGB were found in the older literature; in the contemporary series, there were few reports of GBC associated with a PGB. CONCLUSIONS Porcelain gallbladder is only weakly associated with GBC. Prophylactic cholecystectomy is not indicated for PGB alone and should be performed only in patients with conventional indications for cholecystectomy. A laparoscopic approach is appropriate for most patients with a PGB.

Role of p53, Bax, p21, and DNA-PKcs in radiation sensitivity of HCT-116 cells and xenografts.

BACKGROUND Molecular factors that dictate tumor response to ionizing radiation in rectal cancer are not well described. METHODS We investigated the contribution of p53, p21, Bax, and DNA-PKcs in response to ionizing radiation in an isogeneic colorectal cancer system in vitro and in vivo. RESULTS HCT-116 DNA-PKcs(-/-) cells and xenografts were radiosensitive compared with wild-type (WT) HCT-116 cells. HCT-116 p53(-/-) cells and tumor xenografts displayed a radioresistant phenotype. Separately, p21 or Bax deficiency was associated with a radiosensitive phenotype in vitro and in vivo. In vivo, Bax deficiency led to increased tumor necrosis and decreased microvessel density. In vitro, HCT-116 Bax(-/-) cells had decreased levels of vascular endothelial growth factor. HCT-116 WT cells had a more radioresistant phenotype after pancaspase inhibition, but pancaspase inhibition did not alter radiosensitivity in HCT-116 Bax(-/-) cells subjected to ionizing radiation. There was no difference in cell growth in HCT-116 WT cells subjected to transient apoptosis-inducing factor (AIF) inhibition; however, HCT-116 Bax(-/-) cells treated with AIF siRNA followed by ionizing radiation had a significant survival advantage compared with control-treated cells, implicating AIF in the radiosensitivity of Bax(-/-) cells. CONCLUSION These data might be used along with other markers to predict response to radiation in patients with rectal cancer.

Biological mesh implants for abdominal hernia repair: US food and drug administration approval process and systematic review of its efficacy

IMPORTANCE Expensive biological mesh materials are increasingly used to reinforce abdominal wall hernia repairs. The clinical and cost benefit of these materials are unknown. OBJECTIVES To review the published evidence on the use of biological mesh materials and to examine the US Food and Drug Administration (FDA) approval history for these devices. EVIDENCE ACQUISITION Search of multiple electronic databases (Ovid, MEDLINE, EMBASE, Cochrane Systematic Reviews, Cochrane Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, and Cochrane National Health Service Economic Evaluation Database) to identify articles published between 1948 and June 30, 2015, on the use of biological mesh materials used to reinforce abdominal wall hernia repair. Keywords searched included surgical mesh, abdominal hernia, recurrence, infection, fistula, bioprosthesis, biocompatible materials, absorbable implants, dermis, and collagen. The FDA online database for 510(k) clearances was reviewed for all commercially available biological mesh materials. The median national price for mesh materials was established by a benchmarking query through several Integrated Delivery Network and Group Purchasing Organization tools. EVIDENCE SYNTHESIS Of 274 screened articles, 20 met the search criteria. Most were case series that reported results of convenience samples of patients at single institutions with a variety of clinical problems. Only 3 of the 20 were comparative studies. There were no randomized clinical trials. In total, outcomes for 1033 patients were described. Studies varied widely in follow-up time, operative technique, meshes used, and patient selection criteria. Reported outcomes and clinical outcomes, such as fistula formation and infection, were inconsistently reported across studies. Conflicts of interest were not reported in 16 of the 20 studies. Recurrence rates ranged from 0% to 80%. All biological mesh devices were approved by the FDA based on substantial equivalence to a group of nonbiological predicate devices that, on average, were one-third less costly. CONCLUSIONS AND RELEVANCE There is insufficient evidence to determine the extra costs associated with or the clinical efficacy of biological mesh materials for the repair of abdominal wall hernia.

Intestinal polyp formation in the Apcmin mouse: Effects of levels of dietary calcium and altered vitamin D homeostasis

This study evaluated the effects of various levels of dietary calcium on polyp formation, vitamin D homeostasis, and fecal bile acids in the Apcmin mouse. Female Apcmin mice were randomized to three groups and fed a purified diet with either half or double the level of calcium in control AIN-93G. Serum 25-OH-D and fecal bile acids were measured at weeks 0 and 12 of treatment. Mice were killed for polyp scoring by two observers blinded to treatment after 12 weeks. Results show there was no difference in polyp number or tumor load with dietary calcium in any treatment group. Serum 25-OH-D was reduced and total fecal bile acids were increased in animals that received the high calcium diet. We have previously shown that vitamin D supplementation diminishes polyp load; the lack of effect of an altered calcium diet seen here may be due to a disturbance in vitamin D homeostasis.

Clostridium difficile enteritis: A report of two cases and systematic literature review

Clostridium difficile (C. difficile) is the most common cause of healthcare associated infectious diarrhea. In the last decade, the incidence of C. difficile infection has increased dramatically. The virulence of C. difficile has also increased recently with toxigenic strains developing. C. difficile is generally a disease of the colon and presents with abdominal pain and diarrhea due to colitis. However, C. difficile enteritis has been reported rarely. The initial reports suggested mortality rates as high as 66%. The incidence of C. difficile enteritis appears to be increasing in parallel to the increase in colonic infections. We present two cases of patients who had otherwise uneventful abdominal surgery but subsequently developed C. difficile enteritis. Our literature review demonstrates 81 prior cases of C. difficile enteritis described in case reports. The mortality of the disease remains high at approximately 25%. Early recognition and intervention may reduce the high mortality associated with this disease process.

Human Colon Cancer Cells Deficient in DCC Produce Abnormal Transcripts in Progression of Carcinogenesis

Expressive loss of the tumor suppressor deleted in colon cancer (DCC) may be superior to lymph node status in predicting patient survival for intermediate stage colon cancer. A polymerase chain reaction (PCR)-based method for detecting DCC would be ideal as a prognostic indicator. DCC is an alternatively spliced molecule; thus, reliability of a PCR test for DCC will depend on amplifying only those regions of the molecule that are lost in the progression of colon cancer. For this reason, we studied a colon cancer cell line model at different stages of tumor progression to determine the alternative splice pattern for DCC. A commercially available colon cancer cell line system at different stages of tumor progression was used to identify which DCC exons are lost by western blot analysis, PCR, and RT-PCR techniques. Colon cancers express abnormal DCC transcripts. The proximal and distal exons are present (exons 2 and 28–29). Exons located in the center of the molecule are absent (6–7 and 18–23). This correlated to DCC protein loss in the cell lines. For clinical utility as a disease marker, exons in the middle portion of the DCC molecule that are spliced out should be utilized. Amplification of the proximal and distal regions will result in falsely concluding that DCC is present when its protein product is not expressed.