Publications by authors named "Brent Matthews"

139 Publications

Acuity, outcomes, and trends in the transfer of surgical patients: a national study.

Surg Endosc 2016 Apr 3;30(4):1301-9. Epub 2015 Jul 3.

Division of GI and Minimally Invasive Surgery, Carolinas Medical Center, 1025 Morehead Medical Drive, Suite 300, Charlotte, NC, 28204, USA.

Introduction: With the regionalization of surgical care, reduction in the rural workforce, rising healthcare costs, and increasing focus on surgical outcomes, appropriate transfer of surgical patients is an increasingly important aspect of health care. This study examines patients transferred for surgical intervention through a national sample.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database was queried from 2005 to 2012 for surgery patients who were transferred from an outside hospital or emergency department (ED) and compared patients undergoing surgery without transfer. Patients were divided into two time periods (TP): 2005-2008 (TP1) and 2008-2012 (TP2) for analysis; patient characteristics and top CPT codes for each TP were collected. Univariate analysis and matched cohorts were used to compare the groups.

Results: Overall, 61,204 patients were transferred and underwent surgery. The rate of transferred surgery patients increased from 3.2% in TP1 to 4.5% in TP2 (p < 0.0001). Compared to non-transferred patients, transferred patients had higher rates of diabetes (23.4 vs. 17.6%, p < 0.0001), tobacco use (27.9 vs. 20.3%, p < 0.0001), Charlson comorbidity index (mean score 1.5 vs. 0.8, p < 0.0001), preoperative sepsis (32.0 vs. 9.4%, p < 0.0001), and need for emergent surgery (41.3 vs. 14.4%, p < 0.0001). From TP1 to TP2, there was an increase in transferred patients who were obese (33.9-36.4%, p < 0.0001) and had emergent transfers (39.6-41.8%, p < 0.0001), with a decrease in diabetic patients (24.7-23.1%, p < 0.0001). From TP1 to TP2, transferred patients had more minor complications (17.7-31.0%, p < 0.0001), but fewer major complications (32.1-23.9%, p < 0.0001) and lower 30-day mortality (11.8-8.1%, p < 0.0001).

Conclusions: Patients transferred for surgery represent a higher acuity population than non-transferred patients, and the number of transfers continues to rise. Even when matched by comorbidities, transferred patients have worse outcomes. Surgical sub-specialization and physician tiering may complicate future transfer practices. Efficient transfers, effective physician communication, and ready availability of medical records are critical in improving patient transfers.
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http://dx.doi.org/10.1007/s00464-015-4361-0DOI Listing
April 2016

Remodeling Characteristics and Collagen Distributions of Biologic Scaffold Materials Biopsied From Postmastectomy Breast Reconstruction Sites.

Ann Plast Surg 2015 Jul;75(1):74-83

From the *Section of Minimally Invasive Surgery, Department of Surgery, †Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO; ‡Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH; and §Department of Biostatistics, Washington University School of Medicine, St. Louis, MO.

Objective: The study purpose was to evaluate the associations between patient characteristics and the histologic remodeling scores of acellular dermal matrices (ADMs) biopsied from breast reconstruction sites in the first attempt to generate a multivariable risk prediction model of nonconstructive remodeling. It was hypothesized that host characteristics and surgical site assessments predict the degree of graft remodeling for ADMs used during breast reconstruction.

Methods: The ADMs were biopsied from the breast reconstruction sites of n = 62 patients during a subsequent breast procedure, stained with hematoxylin-eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell types, cell infiltration, extracellular matrix deposition, scaffold degradation, fibrous encapsulation, and neovascularization) and a mean composite score. Biopsies were stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a P value of 0.20 or less.

Results: The composite score model yielded 3 variables: pack-year history, corticosteroid use, and radiation timing (r pseudo = 0.81). The model for collagen I yielded 2 variables: corticosteroid use and reason for reoperation (r pseudo = 0.78). The model for collagen III yielded 1 variable: reason for reoperation (r pseudo = 0.35).

Conclusions: These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances most likely to experience nonconstructive remodeling of biologic grafts used to reconstruct the breast.
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http://dx.doi.org/10.1097/SAP.0000000000000538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4466066PMC
July 2015

National outcomes of laparoscopic Heller myotomy: operative complications and risk factors for adverse events.

Surg Endosc 2015 Nov 15;29(11):3097-105. Epub 2015 Jan 15.

Division of Gastrointestinal and Minimally Invasive Surgery, Department of Surgery, Carolinas Medical Center, 1025 Morehead Medical Drive, Suite 300, Charlotte, NC, 28204, USA.

Introduction: Laparoscopic Heller myotomy (LHM) has supplanted an open approach due to decreased operative morbidity. Our goal was to quantify the incidence of peri-operative complications and identify risk factors for adverse outcomes in LHM.

Methods: All LHM were queried from 2005 to 2011 from the National Surgical Quality Improvement Program database. Adverse outcomes were identified, and univariate and stepwise logistic regression (MVR) was then performed to quantify association.

Results: There were 1,237 LHM in the study period. Patient averages were: age 51.9 ± 16.8 years, BMI 27.3 ± 6.6 kg/m(2), Charlson comorbidity index (CCI) 0.2 ± 0.6. 15.3 % had >10 % body mass loss in the preoperative 6 months. During surgery, 10.2 % underwent concomitant EGD, and mean operative time was 141.6 ± 63.4 min. There were 7(0.06 %) wound complications, 22(1.8 %) general complications, and 30(2.4 %) major complications. Average length of stay (LOS) was 2.8 ± 5.5 days. The rate of readmission and reoperation were 3.1 and 2.3 %, respectively, and there were 4(0.03 %) deaths. General and major complications were associated with alcohol use, pack-years of smoking, weight loss, history of stroke, radiation therapy, and longer operative times (p < 0.05); however, these factors did not remain significant on MVR (p > 0.05). Operative time was found to be significantly longer by 35.3 min for inpatients, 43.1 min in functionally dependent patients, 50.0 min in preoperative septic patients, and 17.2 min with concomitant EGD (p < 0.01 for all). LOS was found to be longer by 1.9 days for inpatients, 1.8 days in ASA category ≥3, and 1.2 days per one point increase in CCI (p < 0.001 for all).

Conclusion: LHM is being performed nationally with a low incidence of operative complications and mortality. General and major complications following LHM are associated with patient alcohol use, pack-years of smoking, weight loss, history of stroke, radiation therapy, and longer operative times. Additionally, independent predictors of longer operative time and LOS were identified.
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http://dx.doi.org/10.1007/s00464-014-4054-0DOI Listing
November 2015

The impact of chemotherapy and radiation therapy on the remodeling of acellular dermal matrices in staged, prosthetic breast reconstruction.

Plast Reconstr Surg 2015 Jan;135(1):43e-57e

St. Louis, Mo.; and Cleveland, Ohio From the Division of Plastic and Reconstructive Surgery, the Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine; and the Department of Anatomic Pathology, Cleveland Clinic.

Background: An acellular dermal matrix will typically incorporate, in time, with the overlying mastectomy skin flap. This remodeling process may be adversely impacted in patients who require chemotherapy and radiation, which influence neovascularization and cellular proliferation.

Methods: Multiple biopsy specimens were procured from 86 women (n = 94 breasts) undergoing exchange of a tissue expander for a breast implant. These were divided by biopsy location: submuscular capsule (control) as well as superiorly, centrally, and inferiorly along the paramedian acellular dermis. Specimens were assessed for cellular infiltration, cell type, fibrous encapsulation, scaffold degradation, extracellular matrix deposition, neovascularization, mean composite remodeling score, and type I and III collagen. Patients were compared based on five oncologic treatment groups: no adjuvant therapy (untreated), neoadjuvant chemotherapy with or without radiation, and chemotherapy with or without radiation.

Results: Biopsy specimens were procured 45 to 1805 days after implantation and demonstrated a significant reduction in type I collagen over time. Chemotherapy adversely impacted fibrous encapsulation (p = 0.03). Chemotherapy with or without radiation adversely impacted type I collagen (p = 0.02), cellular infiltration (p < 0.01), extracellular matrix deposition (p < 0.04), and neovascularization (p < 0.01). Radiation exacerbated the adverse impact of chemotherapy for several remodeling parameters. Neoadjuvant chemotherapy also caused a reduction in type I (p = 0.01) and III collagen (p = 0.05), extracellular matrix deposition (p = 0.03), and scaffold degradation (p = 0.02).

Conclusion: Chemotherapy and radiation therapy limit acellular dermal matrix remodeling.

Clinical Question/level Of Evidence: Therapeutic, III.
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http://dx.doi.org/10.1097/PRS.0000000000000807DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4515029PMC
January 2015

The current status of biosynthetic mesh for ventral hernia repair.

Surg Technol Int 2014 Nov;25:114-21

Division of Gastrointestinal and Minimally Invasive Surgery, Department of Surgery, Carolinas Medical Center, Charlotte, North Carolina.

Although synthetic mesh has dramatically reduced recurrence in elective hernia repair, its use in contaminated surgical fields has been traditionally associated with complications such as wound sepsis, enterocutaneous fistulas, and chronic prosthetic infection. Biologic meshes emerged in the late 1990s with a rapid popularity fueled largely by the demand for an appropriate substitute in lieu of synthetic mesh in these complex cases; however, the high cost and rate of hernia recurrence have tempered the initial enthusiasm. Biosynthetic meshes were developed as a possible cost-effective alternative to both synthetic and tissue-derived products. Using biodegradable polymers instead of animal or cadaver tissue, they provide a temporary scaffold for deposition of proteins and cells necessary for tissue ingrowth, neovascularization, and host integration. Herein we review the current status of biosynthetic meshes for hernia repair.
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November 2014

Effect of acellular human dermis buttress on laparoscopic hiatal hernia repair.

Surg Endosc 2015 Aug 16;29(8):2291-7. Epub 2014 Oct 16.

William Beaumont Army Medical Center, El Paso, TX, USA.

Purpose: The objective of this study was to evaluate the performance of acellular human dermis reinforcement during laparoscopic hiatal hernia repair.

Methods: A prospective non-randomized, single institution study enrolled patients undergoing laparoscopic hiatal hernia repair. Acellular human dermis, FlexHD (Musculoskeletal Transplant Foundation, Edison, NJ) or AlloDerm (LifeCell Inc., Branchburg, NJ) were used to buttress the repair after primary closure. A protocol barium swallow (BAS) was performed at 6 months and then as needed due to clinical indications. Primary outcome measure was recurrence. Patients completed preoperative and postoperative GERD symptom questionnaires and quality of life surveys (SF-36). Kruskal-Wallis ANOVA, Student's t test, Fisher's exact test, or Wilcoxon signed-rank test were utilized as appropriate (p < 0.05 considered statistically significant).

Results: Fifty-four patients (10 men and 44 women) with a mean age of 62 ± 10 years underwent laparoscopic hiatal hernia repair using Flex HD (n = 37) or AlloDerm (n = 17). Both groups were similar with respect to gender, age, hiatus size, hernia type [sliding/Type I (n = 14) or paraesophageal/Type III/IV (n = 40)], esophageal motor function (manometry), preoperative SF-36 quality of life surveys, and GERD symptom questionnaires. Forty-seven patients (87 %) completed the BAS at 6 months; each group had two recurrences (p = 0.597). At median follow-up of 33 months, there were 3 recurrences (18 %) in the AlloDerm group and 5 recurrences (14 %) in the Flex HD group (p = 0.365). Minimal differences in GERD symptoms or SF-36 scores were detected between groups. However, anti-reflux medication usage, GERD symptoms, and quality of life significantly improved for both groups after laparoscopic hiatal hernia repair.

Conclusions: Laparoscopic hiatal hernia repair with acellular human dermis reinforcement results in improvement of GERD-related symptoms and quality of life without mesh-associated complications. The type of acellular human dermis did not influence recurrence rate.
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http://dx.doi.org/10.1007/s00464-014-3946-3DOI Listing
August 2015

Evaluation of absorbable mesh fixation devices at various deployment angles.

Surg Endosc 2015 Jun 8;29(6):1605-13. Epub 2014 Oct 8.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO, 63110, USA.

Background: Hernia repair failure may occur due to suboptimal mesh fixation by mechanical constructs before mesh integration. Construct design and acute penetration angle may alter mesh-tissue fixation strength. We compared acute fixation strengths of absorbable fixation devices at various deployment angles, directions of loading, and construct orientations.

Methods: Porcine abdominal walls were sectioned. Constructs were deployed at 30°, 45°, 60°, and 90° angles to fix mesh to the tissue specimens. Lap-shear testing was performed in upward, downward, and lateral directions in relation to the abdominal wall cranial-caudal axis to evaluate fixation. Absorbatack™ (AT), SorbaFix™ (SF), and SecureStrap™ in vertical (SSV) and horizontal (SSH) orientations in relation to the abdominal wall cranial-caudal axis were tested. Ten tests were performed for each combination of device, angle, and loading direction. Failure types and strength data were recorded. ANOVA with Tukey-Kramer adjustments for multiple comparisons and χ (2) tests were performed as appropriate (p < 0.05 considered significant).

Results: At 30°, SSH and SSV had greater fixation strengths (12.95, 12.98 N, respectively) than SF (5.70 N; p = 0.0057, p = 0.0053, respectively). At 45°, mean fixation strength of SSH was significantly greater than SF (18.14, 11.40 N; p = 0.0002). No differences in strength were identified at 60° or 90°. No differences in strength were noted between SSV and SSH with different directions of loading. No differences were noted between SS and AT at any angle. Immediate failure was associated with SF (p < 0.0001) and the 30° tacking angle (p < 0.01).

Conclusions: Mesh-tissue fixation was stronger at acute deployment angles with SS compared to SF constructs. The 30° angle and the SF device were associated with increased immediate failures. Varying construct and loading direction did not generate statistically significant differences in the fixation strength of absorbable fixation devices in this study.
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http://dx.doi.org/10.1007/s00464-014-3850-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4390414PMC
June 2015

Remodeling characteristics and collagen distribution in synthetic mesh materials explanted from human subjects after abdominal wall reconstruction: an analysis of remodeling characteristics by patient risk factors and surgical site classifications.

Surg Endosc 2014 Jun 18;28(6):1852-65. Epub 2014 Jan 18.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO, 63110, USA.

Background: The purpose of this study was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of synthetic meshes biopsied from their abdominal wall repair sites in the first attempt to generate a multivariable risk prediction model of non-constructive remodeling.

Methods: Biopsies of the synthetic meshes were obtained from the abdominal wall repair sites of 51 patients during a subsequent abdominal re-exploration. Biopsies were stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell infiltration, cell types, extracellular matrix deposition, inflammation, fibrous encapsulation, and neovascularization) and a mean composite score (CR). Biopsies were also stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a threshold p value of ≤0.200.

Results: The model selection process for the extracellular matrix score yielded two variables: subject age at time of mesh implantation, and mesh classification (c-statistic = 0.842). For CR score, the model selection process yielded two variables: subject age at time of mesh implantation and mesh classification (r (2) = 0.464). The model selection process for the collagen III area yielded a model with two variables: subject body mass index at time of mesh explantation and pack-year history (r (2) = 0.244).

Conclusion: Host characteristics and surgical site assessments may predict degree of remodeling for synthetic meshes used to reinforce abdominal wall repair sites. These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances for which non-constructive remodeling of an abdominal wall repair site with synthetic mesh reinforcement is most likely to occur.
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http://dx.doi.org/10.1007/s00464-013-3405-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035433PMC
June 2014

Ventralight ST and SorbaFix versus Physiomesh and Securestrap in a porcine model.

JSLS 2013 Oct-Dec;17(4):549-59

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO, USA.

Background And Objectives: The objective of this study was to compare mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response of Ventralight ST/SorbaFix (C.R. Bard/Davol, Warwick, RI, USA) with Physiomesh/Securestrap (Ethicon, Somerville, NJ, USA) in a porcine model of laparoscopic ventral hernia repair.

Methods: Standard laparoscopic technique was used to bilaterally implant meshes in 10 female Yorkshire swine. Each animal received either two Ventralight ST meshes (oval shaped, 10.2 × 15.2 cm) or two Physiomesh meshes (oval shaped 10 × 15 cm), one on either side of the midline. The meshes were fixated to the intact peritoneum with either SorbaFix (for animals receiving Ventralight ST) or Securestrap (for animals receiving Physiomesh). There were 5 animals in each group, yielding 10 of each meshfixation combination. Mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response were evaluated after 14 days by image analysis, mechanical testing, and histologic staining (hematoxylin-eosin, Masson trichrome, picrosirius red, and von Willebrand factor).

Results: Ventralight ST/SorbaFix and Physiomesh/Securestrap exhibited a similar percentage of mesh contracture, percentage of adhesion coverage, adhesion tenacity, collagen deposition, and levels of necrosis (P > .05 in all cases). However, Ventralight ST/SorbaFix exhibited significantly less inflammation (P = .0001), fibrosis (P = .0017), hemorrhage (P = .0001), and angiogenesis (P = .0032) and significantly greater strength of tissue ingrowth (P = .0003) than Physiomesh/Securestrap after the 14-day implantation period.

Conclusions: Ventralight ST/SorbaFix exhibited more favorable strength of tissue ingrowth and histologic response and similar mesh contracture and adhesion characteristics compared with Physiomesh/Securestrap over a short-term 14-day implantation period in a preclinical porcine model.
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http://dx.doi.org/10.4293/108680813X13693422520125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3866058PMC
September 2014

Remodeling characteristics and collagen distribution in biological scaffold materials explanted from human subjects after abdominal soft tissue reconstruction: an analysis of scaffold remodeling characteristics by patient risk factors and surgical site classifications.

Ann Surg 2015 Feb;261(2):405-15

*Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St Louis, MO †Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH ‡Department of Biostatistics, Washington University School of Medicine, St Louis, MO §Meharry Medical College, Nashville, TN; and ¶William Beaumont Army Medical Center, El Paso, TX.

Objective: The study purpose was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of biologic meshes biopsied from abdominal soft tissue repair sites in the first attempt to generate a multivariable risk-prediction model of nonconstructive remodeling.

Background: Host characteristics and surgical site assessments may predict remodeling degree for biologic meshes used to reinforce abdominal tissue repair sites.

Methods: Biologic meshes were biopsied from the abdominal tissue repair sites of n = 40 patients during an abdominal reexploration, stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell types, cell infiltration, extracellular matrix deposition, scaffold degradation, fibrous encapsulation, and neovascularization) and a mean composite score. Biopsies were stained with Sirius Red and Fast Green and analyzed to determine the collagen I:III ratio. On the basis of univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using P ≤ 0.200.

Results: The model selection process for cell infiltration score yielded 2 variables: age at mesh implantation and mesh classification (C statistic = 0.989). For the mean composite score, the model selection process yielded 2 variables: age at mesh implantation and mesh classification (r = 0.449).

Conclusions: These preliminary results constitute the first steps in generating a risk-prediction model that predicts the patients and clinical circumstances most likely to experience nonconstructive remodeling of abdominal tissue repair sites with biologic mesh reinforcement.
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http://dx.doi.org/10.1097/SLA.0000000000000471DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072753PMC
February 2015

A material cost-minimization analysis for hernia repairs and minor procedures during a surgical mission in the Dominican Republic.

Surg Endosc 2014 Mar 26;28(3):747-66. Epub 2013 Oct 26.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO, 63110, USA,

Introduction: Expenditures on material supplies and medications constitute the greatest per capita costs for surgical missions. We hypothesized that supply acquisition at non-profit organization (NPO) costs would lead to significant cost-savings compared with supply acquisition at US academic institution costs from the provider perspective for hernia repairs and minor procedures during a surgical mission in the Dominican Republic.

Methods: Items acquired for a surgical mission were uniquely QR-coded for accurate consumption accounting. Both NPO and US academic institution unit costs were associated with each item in an electronic inventory system. Medication doses were recorded and QR codes for consumed items were scanned into a record for each sampled procedure. Mean material costs and cost-savings ± SDs were calculated in US dollars for each procedure type. Cost-minimization analyses between the NPO and the US academic institution platforms for each procedure type ensued using a two-tailed Wilcoxon matched-pairs test with α = 0.05. Item utilization analyses generated lists of most frequently used materials by procedure type.

Results: The mean cost-savings of supply acquisition at NPO costs for each procedure type were as follows: $482.86 ± $683.79 for unilateral inguinal hernia repair (n = 13); $332.46 ± $184.09 for bilateral inguinal hernia repair (n = 3); $127.26 ± $13.18 for hydrocelectomy (n = 9); $232.92 ± $56.49 for femoral hernia repair (n = 3); $120.90 ± $30.51 for umbilical hernia repair (n = 8); $36.59 ± $17.76 for minor procedures (n = 26); and $120.66 ± $14.61 for pediatric inguinal hernia repair (n = 7).

Conclusion: Supply acquisition at NPO costs leads to significant cost-savings compared with supply acquisition at US academic institution costs from the provider perspective for inguinal hernia repair, hydrocelectomy, umbilical hernia repair, minor procedures, and pediatric inguinal hernia repair during a surgical mission in the Dominican Republic. Item utilization analysis can generate minimum-necessary material lists for each procedure type to reproduce cost-savings for subsequent missions.
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http://dx.doi.org/10.1007/s00464-013-3253-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943836PMC
March 2014

Incidence, mechanisms, and outcomes of esophageal and gastric perforation during laparoscopic foregut surgery: a retrospective review of 1,223 foregut cases.

Surg Endosc 2014 Jan 7;28(1):85-90. Epub 2013 Sep 7.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 S Euclid Avenue, Box 8109, St. Louis, MO, 63110, USA,

Background: Intraoperative perforation is a potentially major complication of laparoscopic (lap) foregut surgery. This study analyzed the incidence, mechanism, and outcomes of intraoperative perforations during these procedures in a large institutional experience.

Methods: All patients who underwent lap foregut surgery including laparoscopic antireflux surgery (LARS), paraesophageal hernia (PEH) repair, Heller myotomy, and reoperative hiatal hernia (redo HH) repair at the authors' institution from August 2004 to September 2012 were reviewed retrospectively. Perforation events and postoperative outcomes were analyzed, and complications were graded by the modified Clavien system. All data are expressed as means ± standard deviations or as medians. Statistical analysis was performed using Fisher's exact test and the Mann-Whitney U test.

Results: In this study, the repairs for 1,223 patients were analyzed (381 LARS procedures, 379 PEH repairs, 313 Heller myotomies, 150 redo HH repairs). Overall, 51 patients (4.2 %) had 56 perforations resulting from LARS (n = 4, 1 %), PEH repair (n = 7, 1.8 %), Heller myotomy (n = 18, 5.8 %), and redo HH repair (n = 22, 14.6 %). Redo HH was significantly more likely to result in perforations than LARS or PEH repair (p < 0.001). The locations of the perforations were esophageal in 13 patients (23.6 %), gastric in 40 patients (72.7 %), and indeterminate in 2 patients (3.6 %). The most common mechanisms of perforations were suture placement for LARS (75 %) and traction for PEH repair (43 %) and for Heller myotomy during the myotomy (72 %). The most redo HH perforations resulted from dissection/wrap takedown (73 %) and traction (14 %). Perforations were recognized and repaired intraoperatively in 43 cases (84 %) and postoperatively in eight cases (16 %). Perforations discovered postoperatively were more likely to require reoperation (75 vs 2 %; p < 0.001), to require more gastrointestinal and radiologic interventions (50 vs 2 %; p = 0.004), and to have higher morbidity (88 vs 26 %; p = 0.004) than perforations recognized intraoperatively.

Conclusions: In a high-volume center, intraoperative perforations are the most frequent with reoperative HH repair. If perforations are recognized and repaired intraoperatively, they require minimal postoperative intervention. Unrecognized perforations usually require reoperation and result in significantly greater morbidity.
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http://dx.doi.org/10.1007/s00464-013-3167-1DOI Listing
January 2014

Characterization of the Mechanical Strength, Resorption Properties, and Histologic Characteristics of a Fully Absorbable Material (Poly-4-hydroxybutyrate-PHASIX Mesh) in a Porcine Model of Hernia Repair.

ISRN Surg 2013 28;2013:238067. Epub 2013 May 28.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.

Purpose. Poly-4-hydroxybutyrate (P4HB) is a naturally derived, absorbable polymer. P4HB has been manufactured into PHASIX Mesh and P4HB Plug designs for soft tissue repair. The objective of this study was to evaluate mechanical strength, resorption properties, and histologic characteristics in a porcine model. Methods. Bilateral defects were created in the abdominal wall of n = 20 Yucatan minipigs and repaired in a bridged fashion with PHASIX Mesh or P4HB Plug fixated with SorbaFix or permanent suture, respectively. Mechanical strength, resorption properties, and histologic characteristics were evaluated at 6, 12, 26, and 52 weeks (n = 5 each). Results. PHASIX Mesh and P4HB Plug repairs exhibited similar burst strength, stiffness, and molecular weight at all time points, with no significant differences detected between the two devices (P > 0.05). PHASIX Mesh and P4HB Plug repairs also demonstrated significantly greater burst strength and stiffness than native abdominal wall at all time points (P < 0.05), and material resorption increased significantly over time (P < 0.001). Inflammatory infiltrates were mononuclear, and both devices exhibited mild to moderate granulation tissue/vascularization. Conclusions. PHASIX Mesh and P4HB Plug demonstrated significant mechanical strength compared to native abdominal wall, despite significant material resorption over time. Histological assessment revealed a comparable mild inflammatory response and mild to moderate granulation tissue/vascularization.
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http://dx.doi.org/10.1155/2013/238067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679684PMC
June 2013

Risk factors affecting operative approach, conversion, and morbidity for adrenalectomy: a single-institution series of 402 patients.

Surg Endosc 2013 Jul 13;27(7):2342-50. Epub 2013 Feb 13.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8109, St. Louis, MO 63111, USA.

Background: Risk factors for selecting patients for open adrenalectomy (OA) and for conversion are limited in most series. This study aimed to investigate variables that are important in selecting patients for OA, predict risk of conversion from laparoscopic adrenalectomy (LA), and impact 30-day outcomes of OA and LA.

Methods: A retrospective cohort study of prospectively collected data was conducted. Patients (≥ 16 years old) who underwent adrenalectomy in the Division of General Surgery at Barnes-Jewish Hospital (1993-2010) were grouped by operative approach (LA vs. OA) and compared using nonparametric tests and regression analyses (α < 0.05).

Results: In total, 402 patients underwent 422 adrenalectomies. Compared to LA patients, those in the OA group were older (p = 0.02), had higher ASA scores (p = 0.04), larger tumor size (p < 0.01), and fewer functioning lesions (p < 0.01). OA patients more often required concurrent procedures (p < 0.01), had a longer operative time (p = 0.04), more intraoperative complications (p = 0.02), higher estimated blood loss (EBL), and larger transfusion requirement. Preoperative factors that predicted selection for OA were higher patient age (p = 0.01), higher ASA score (p = 0.03), larger tumor size (p < 0.01), nonfunctioning lesion (p < 0.01), diagnosis of adrenocortical carcinoma (p < 0.01), and the need for concomitant procedures (p < 0.01). Conversion to open or hand-assisted approach occurred in 6.2 % of LA patients. Preoperative risks for conversion included large tumor size (>8 cm) and need for concomitant procedures (p < 0.01). Multivariate analysis revealed that large indeterminate adrenal mass, adrenocortical carcinoma, tumor size (>6 cm), an open operation, conversion, concomitant procedures, operative time >180 min, and EBL >200 mL were predictors of 30-day morbidity.

Conclusions: Adrenal tumor size and need for concurrent procedures significantly impact the selection of patients for OA, the likelihood of conversion, and perioperative morbidity. These metrics should be considered when assessing operative approach and risks for adrenalectomy.
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http://dx.doi.org/10.1007/s00464-013-2789-7DOI Listing
July 2013

Laparoscopic adrenalectomy for cancer.

Surg Oncol Clin N Am 2013 Jan;22(1):111-24, vi-vii

Department of General Surgery, William Beaumont Army Medical Center, 5005 North Piedras, El Paso, TX 79920, USA.

Laparoscopic procedures are preferred by surgeons and patients alike because of decreased pain, reduced perioperative morbidity, and an earlier return to self-reliance. During the last decade, laparoscopic adrenalectomy has become the technique most commonly used for the removal of benign adrenal tumors. The indications for laparoscopy in malignant adrenal tumors remains controversial, because oncologic resections have not been reproducible compared with open techniques.
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http://dx.doi.org/10.1016/j.soc.2012.08.006DOI Listing
January 2013

Outcomes of resection of extra-adrenal pheochromocytomas/paragangliomas in the laparoscopic era: a comparison with adrenal pheochromocytoma.

Surg Endosc 2013 Feb 31;27(2):428-33. Epub 2012 Aug 31.

Department of Surgery, Institute for Minimally Invasive Surgery, Washington University School of Medicine, 660 S Euclid Ave., Box 8109, St. Louis, MO 63110, USA.

Introduction: Laparoscopic adrenalectomy (LA) is the standard for removal of adrenal pheochromocytomas (pheos), but laparoscopic (LAP) resection of paragangliomas (PGs) is controversial. This study analyzes our results of resection of PGs in the LAP era.

Methods: A retrospective record review of all patients who underwent resection of intra-abdominal PGs from 1998 to 2011 was performed. Pre- and postoperative clinical, radiologic, biochemical, and pathologic data for LAP resection of PGs were compared with patients who underwent LA for adrenal pheo (LA pheo; n = 62). Statistical analysis was performed and data are reported as mean ± SD.

Results: Fifteen patients had resection of PGs (6 OPEN, 9 LAP) and 62 had LA pheo. Most common PG locations were perirenal or renal hilum (n = 6) and para-aortic (n = 4). One LAP PG was converted to OPEN due to inflammation from a prior biopsy. Mean age of LAP PGs was 45.3 ± 13.2 years, and mean tumor size was 3.3 ± 2.1 cm. OPEN PGs were larger (5.1 vs. 3.3 cm), had shorter operative times (173 vs. 254 min), and longer hospitalization (5.7 vs. 2.6 days) and ICU stays (1.33 vs. 0.22 days) compared with LAP PGs (p ≤ 0.05). Compared with LA pheo, operative times for LAP PG were significantly longer (254 vs. 175 min, p = 0.001) but other outcomes were similar. Complications occurred in 5.9 % of LA pheos, 22 % of LAP PGs and 67 % of OPEN PGs.

Conclusions: Patients with paragangliomas can safely benefit from LAP resection with outcomes similar to adrenal pheos. In the absence of a need for contiguous organ resection, LAP resection of paragangliomas seems to be the preferred surgical approach.
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http://dx.doi.org/10.1007/s00464-012-2451-9DOI Listing
February 2013

Effect of enzymatic degradation on the mechanical properties of biological scaffold materials.

Surg Endosc 2012 Oct 27;26(10):2767-78. Epub 2012 Apr 27.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO 63110, USA.

Background: Biological scaffolds must support a complex balance of resisting enzymatic degradation while promoting tissue remodeling. Thus, the purpose of this study was to evaluate the effects of in vitro enzymatic exposure on the mechanical properties of biological scaffolds. It was hypothesized that exposure to an enzyme solution would result in decreased tensile strength and that crosslinked scaffolds would resist enzymatic degradation more effectively than noncrosslinked scaffolds.

Methods: Nine scaffolds were evaluated (four porcine dermis: Permacol™, CollaMend™, Strattice™, XenMatrix™; two human dermis: AlloMax™, FlexHD(®); two bovine pericardium: Veritas(®), PeriGuard(®); and one porcine small intestine submucosa: Surgisis™). Ten specimens (n = 10) were hydrated in saline at 37 °C and subjected to uniaxial testing to establish baseline properties. 50 specimens (n = 50) were incubated in collagenase solution at 37 °C for 2, 6, 12, 24, or 30 h (n = 10 each group) followed by uniaxial tensile testing.

Results: Tensile strength was significantly reduced after 30 h for CollaMend™, AlloMax™, Veritas(®), Strattice™, XenMatrix™, Permacol™, and FlexHD(®) (p < 0.01), while PeriGuard(®) demonstrated a slight increase in tensile strength (p = 0.0188). Crosslinked bovine pericardium (PeriGuard(®)) maintained greater tensile strength than noncrosslinked bovine pericardium (Veritas(®)) throughout all exposure periods (p < 0.0001). Similarly, crosslinked porcine dermis (Permacol™) maintained greater tensile strength than noncrosslinked porcine dermis (Strattice™ and XenMatrix™) throughout all exposure periods (p < 0.0001).

Conclusions: Materials that deteriorate rapidly after in vitro enzymatic exposure may also deteriorate rapidly in vivo, particularly when exposed to a wound environment with elevated levels of matrix metalloproteinases. Permacol™, CollaMend™, Strattice™, FlexHD(®), and PeriGuard(®) survived the longest incubation period (30 h) and withstood mechanical testing. XenMatrix™, AlloMax™, Veritas(®), and Surgisis™ degraded more quickly and did not survive the longer exposure periods. Scaffolds that maintain strength characteristics after in vitro collagenase exposure may be advantageous for long-term hernia repair scenarios where elevated enzyme levels are expected.
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http://dx.doi.org/10.1007/s00464-012-2277-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3702043PMC
October 2012

Development of novel electrospun absorbable polycaprolactone (PCL) scaffolds for hernia repair applications.

Surg Endosc 2012 Oct 27;26(10):2717-28. Epub 2012 Apr 27.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO 63110, USA.

Introduction: Permanent/nonresorbable hernia repair materials rely on profibrotic wound healing, and repair sites are commonly composed of disorganized tissue with inferior mechanical strength and risk of reherniation. Resorbable electrospun scaffolds represent a novel class of biomaterials, which may provide a unique platform for the design of advanced soft tissue repair materials. These materials are simple, inexpensive, nonwoven materials composed of polymer fibers that readily mimic the natural extracellular matrix. The primary goal of the present study was to evaluate the physiomechanical properties of novel electrospun scaffolds to determine their suitability for hernia repair. Based on previous experimentation, scaffolds possessing ≥ 20 N suture retention strength, ≥ 20 N tear resistance, and ≥ 50 N/cm tensile strength are appropriate for hernia repair.

Methods: Six novel electrospun scaffolds were fabricated by varying combinations of polymer concentration (10-12 %) and flow rate (3.5-10 mL/h). Briefly, poly(ε-caprolactone) (PCL) was dissolved in a solvent mixture and electrospun onto a planar metal collector, yielding sheets with randomly oriented fibers. Physiomechanical properties were evaluated through scanning electron microscopy, laser micrometry, and mechanical testing.

Results: Scanning electron micrographs demonstrated fiber diameters ranging from 1.0 ± 0.1 μm (10 % PCL, 3.5 mL/h) to 1.5 ± 0.2 μm (12 % PCL, 4 mL/h). Laser micrometry demonstrated thicknesses ranging from 0.72 ± 0.07 mm (12 % PCL, 10 mL/h) to 0.91 ± 0.05 mm (10 % PCL, 3.5 mL/h). Mechanical testing identified two scaffolds possessing suture retention strengths ≥ 20 N (12 % PCL, 10 mL/h and 12 % PCL, 6 mL/h), and no scaffolds possessing tear resistance values ≥ 20 N (range, 4.7 ± 0.9 N to 10.6 ± 1.8 N). Tensile strengths ranged from 35.27 ± 2.08 N/cm (10 % PCL, 3.5 mL/h) to 81.76 ± 15.85 N/cm (12 % PCL, 4 mL/h), with three scaffolds possessing strengths ≥ 50 N/cm (12 % PCL, 10 mL/h; 12 % PCL, 6 mL/h; 12 % PCL, 4 mL/h).

Conclusions: Two electrospun scaffolds (12 % PCL, 10 mL/h and 12 % PCL, 6 mL/h) possessed suture retention and tensile strengths appropriate for hernia repair, justifying evaluation in a large animal model. Additional studies examining advanced methods of fabrication may further improve the unique properties of these scaffolds, propelling them into applications in a variety of clinical settings.
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http://dx.doi.org/10.1007/s00464-012-2258-8DOI Listing
October 2012

Effect of repetitive loading on the mechanical properties of biological scaffold materials.

J Am Coll Surg 2012 Aug 21;215(2):216-28. Epub 2012 Apr 21.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St Louis, MO 63110, USA.

Background: Coughing, bending, and lifting raise the pressure inside the abdomen, repetitively increasing stresses on the abdominal wall and the associated scaffold. The purpose of this study was to evaluate the effect of repetitive loading on biological scaffolds. It was hypothesized that exposure to repetitive loading would result in decreased tensile strength and that crosslinked scaffolds would resist these effects more effectively than non-crosslinked scaffolds.

Study Design: Nine materials were evaluated (porcine dermis: Permacol, CollaMend, Strattice, XenMatrix; human dermis: AlloMax, FlexHD; bovine pericardium: Veritas, PeriGuard; and porcine small intestine submucosa: Surgisis; in addition, Permacol, CollaMend, and PeriGuard are crosslinked). Ten specimens were hydrated and subjected to uniaxial tension to establish baseline properties. Thirty specimens were hydrated and subjected to 10, 100, or 1,000 loading cycles (n = 10 each).

Results: Tensile strength remained unchanged for CollaMend, XenMatrix, Veritas, and Surgisis during all cycles (p > 0.05). However, Strattice and AlloMax exhibited reduced tensile strength, and Permacol, FlexHD, and PeriGuard exhibited a slight increase in tensile strength with increasing number of cycles. Crosslinked bovine pericardium (PeriGuard) displayed greater tensile strength than non-crosslinked bovine pericardium (Veritas) and crosslinked porcine dermis (Permacol) exhibited greater tensile strength than non-crosslinked porcine dermis (Strattice, XenMatrix) during all cycles (p < 0.0001).

Conclusions: Materials that rapidly lose strength after repetitive loading might not be appropriate in clinical scenarios involving elevated stresses, such as in patients with high body mass index or when replacing large areas of the abdominal wall without tissue reinforcement, although scaffolds that maintain initial tensile strength can be particularly advantageous.
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http://dx.doi.org/10.1016/j.jamcollsurg.2012.03.006DOI Listing
August 2012

Differentiation of biologic scaffold materials through physicomechanical, thermal, and enzymatic degradation techniques.

Ann Surg 2012 Mar;255(3):595-604

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St Louis, Missouri, USA.

Objective: The objective of this study was to characterize the physicomechanical, thermal, and degradation properties of several types of biologic scaffold materials to differentiate between the various materials.

Background: As more biologic scaffold materials arrive on the market, it is critical that surgeons understand the properties of each material and are provided with resources to determine the suitability of these products for specific applications such as hernia repair.

Methods: Twelve biologic scaffold materials were evaluated, including crosslinked and non-crosslinked; those of bovine, human, and porcine origin; and derivatives of pericardium, dermis, and small intestine submucosa. Physicomechanical, thermal, and degradation properties were evaluated through biomechanical testing, modulated differential scanning calorimetry, and collagenase digestion assays, respectively. Biomechanical testing included suture retention, tear strength, uniaxial tensile, and ball burst techniques.

Results: All scaffolds exhibited suture retention strengths greater than 20 N, but only half of the scaffolds exhibited tear resistance greater than 20 N, indicating that some scaffolds may not provide adequate resistance to tearing. A wide range of burst strengths were observed ranging from 66.2 ± 10.8 N/cm for Permacol to 1,028.0 ± 199.1 N/cm for X-Thick AlloDerm, and all scaffolds except SurgiMend, Strattice, and CollaMend exhibited strains in the physiological range of 10% to 30% (at a stress of 16 N/cm). Thermal analysis revealed differences between crosslinked and non-crosslinked materials with crosslinked bovine pericardium and porcine dermis materials exhibiting a higher melting temperature than their non-crosslinked counterparts. Similarly, the collagenase digestion assay revealed that crosslinked bovine pericardium materials resisted enzymatic degradation significantly longer than non-crosslinked bovine pericardium.

Conclusions: Although differences were observed because of cross-linking, some crosslinked and non-crosslinked materials exhibited very similar properties. Variables other than cross-linking, such as decellularization/sterilization treatments or species/tissue type also contribute to the properties of the scaffolds.
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http://dx.doi.org/10.1097/SLA.0b013e3182445341DOI Listing
March 2012

A review of the composition, characteristics, and effectiveness of barrier mesh prostheses utilized for laparoscopic ventral hernia repair.

Surg Endosc 2012 Feb 5;26(2):566-75. Epub 2011 Sep 5.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO, 63110, USA.

Background: The objective of this review was to provide an overview of the components that comprise each of the eight barrier mesh prostheses commonly utilized for LVHR and to review the current literature related to the characteristics and effectiveness of these materials to guide the general surgeon in selecting the most appropriate material for LVHR.

Methods: Composite prostheses with permanent barriers (Bard™ Composix™ E/X, Bard™ Composix™ L/P, and DUALMESH(®) Biomaterial) were compared to composite prostheses with absorbable barriers (C-QUR™ Mesh, PROCEED™ Surgical Mesh, Bard™ Sepramesh™ IP Composite, Parietex™ Composite, and PHYSIOMESH™) using scanning electron microscopy and a review of the current preclinical and clinical literature.

Results: Clinical studies and preclinical animal models have attempted to determine the adhesion characteristics and effectiveness of barrier mesh prostheses available for ventral hernia repair applications. However, it is difficult to make any definitive statements about the adhesion characteristics and effectiveness of these materials because all meshes were not included in all studies and likewise not compared under identical conditions. Overall, Parietex™ Composite and DUALMESH(®) Biomaterial were cited most frequently for improvement of adhesion characteristics, followed closely by Bard™ Sepramesh™ IP Composite and C-QUR™ Mesh. Bard™ Composix™, PROCEED™ Surgical Mesh, and uncoated polypropylene were cited most frequently as having the most tenacious and extensive adhesions.

Conclusions: Differences observed between the various barrier prostheses are likely attributable to the chemical composition of the barrier or the conditions required for resorption and metabolism of the barrier components. It is likely that the components of these barriers incite a wide range of inflammatory responses resulting in the range of adhesion coverage and tenacity observed in the preclinical and clinical studies reviewed. Clinical trials are needed to more appropriately define the clinical effectiveness of these barriers.
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http://dx.doi.org/10.1007/s00464-011-1899-3DOI Listing
February 2012

Laparoscopic Dor versus Toupet fundoplication following Heller myotomy for achalasia: results of a multicenter, prospective, randomized-controlled trial.

Surg Endosc 2012 Jan 26;26(1):18-26. Epub 2011 Jul 26.

Department of Surgery, Washington University School of Medicine, 660 S Euclid Ave., Box 8109, St. Louis, MO 63110, USA.

Background: The type of fundoplication that should be performed in conjunction with Heller myotomy for esophageal achalasia is controversial. We prospectively compared anterior fundoplication (Dor) with partial posterior fundoplication (Toupet) in patients undergoing laparoscopic Heller myotomy.

Methods: A multicenter, prospective, randomized-controlled trial was initiated to compare Dor versus Toupet fundoplication after laparoscopic Heller myotomy. Outcome measures were symptomatic GERD scores (0-4, five-point Likert scale questionnaire) and 24-h pH testing at 6-12 months after surgery. Data are mean ± SD. Statistical analysis was by Mann-Whitney U test, Wilcoxon signed rank test, and Freidman's test.

Results: Sixty of 85 originally enrolled and randomized patients who underwent 36 Dor and 24 Toupet fundoplications had follow-up data per protocol for analysis. Dor and Toupet groups were similar in age (46.8 vs. 51.7 years) and gender (52.8 vs. 62.5% male). pH studies at 6-12 months in 43 patients (72%: Dor n = 24 and Toupet n = 19) showed total DeMeester scores and % time pH < 4 were not significant between the two groups. Abnormal acid reflux was present in 10 of 24 Dor group patients (41.7%) and in 4 of 19 Toupet patients (21.0%) (p = 0.152). Dysphagia and regurgitation symptom scores improved significantly in both groups compared to preoperative scores. No significant differences in any esophageal symptoms were noted between the two groups preoperatively or at follow-up. SF-36 quality-of-life measures changed significantly from pre- to postoperative for five of ten domains in the Dor group and seven of ten in the Toupet patients (not significant between groups).

Conclusion: Laparoscopic Heller myotomy provides significant improvement in dysphagia and regurgitation symptoms in achalasia patients regardless of the type of partial fundoplication. Although a higher percentage of patients in the Dor group had abnormal 24-h pH test results compared to those of patients who underwent Toupet, the differences were not statistically significant.
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http://dx.doi.org/10.1007/s00464-011-1822-yDOI Listing
January 2012

Biomechanical evaluation of potential damage to hernia repair materials due to fixation with helical titanium tacks.

Surg Endosc 2011 Dec 13;25(12):3890-7. Epub 2011 Jul 13.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO 63110, USA.

Background: This study aimed to determine whether the strength and extensibility of hernia repair materials are negatively influenced by the application of helical titanium tacks.

Methods: This study evaluated 14 meshes including bare polypropylene, macroporous polytetrafluoroethylene, absorbable barrier, partially absorbable mesh, and expanded polytetrafluoroethylene materials. Each mesh provided 15 specimens, which were prepared in 7.5 × 7.5-cm squares. Of these, 5 "undamaged" specimens were subjected to ball-burst testing to determine their biomechanical properties before application of helical titanium tacks (ProTack). To 10 "damaged" specimens 7 tacks were applied 1 cm apart in a 3.5-cm-diameter circle using a tacking force of 25 to 28 N. The tacks were removed from five of the specimens before ball-burst testing and left intact in the remaining five specimens.

Results: The application of tacks had no effect on the tensile strength of Dualmesh, ProLite Ultra, Infinit, Ultrapro, C-QUR Lite (<6 in.), Prolene Soft, or Physiomesh, but the tensile strengths were reduced for Bard Mesh, C-QUR, ProLite, and C-QUR Lite (>6 in.). Most of the meshes did not exhibit significantly different tensile strengths between removal of tacks and tacks left intact. Exceptions included C-QUR, Prolene, Ultrapro, and Bard Soft Mesh, which were weaker with removal of tacks than with tacks left intact during the test. Damage due to the application of helical titanium tacks also caused increased strain at a stress of 16 N/cm for all the meshes except C-QUR Lite (>6 in.) and Physiomesh.

Conclusions: Many of the meshes evaluated in this study exhibited damage in the form of reduced tensile strength and increased extensibility after the application of tacks compared with the corresponding "undamaged" meshes. Meshes with smaller interstices and larger filaments were influenced negatively by the application of helical titanium tacks, whereas mesh designs with larger interstices and smaller filaments tended to maintain their baseline mechanical properties.
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http://dx.doi.org/10.1007/s00464-011-1816-9DOI Listing
December 2011

Clinical outcomes of atypical extra-esophageal reflux symptoms following laparoscopic antireflux surgery.

Surg Endosc 2011 Dec 30;25(12):3852-8. Epub 2011 Jun 30.

Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8109, St. Louis, MO 63110, USA.

Introduction: While it is well established that antireflux surgery is effective in relieving typical gastroesophageal reflux disease (GERD) symptoms such as heartburn and regurgitation, it is currently unclear whether atypical symptoms (cough, hoarseness, wheeze) foreshadow a less satisfactory outcome following laparoscopic antireflux surgery (LARS). The purpose of this study is to critically analyze the clinical outcomes of atypical symptoms in patients undergoing LARS.

Methods: Patients scheduled for LARS for GERD were prospectively enrolled over a 7-year period; all subjects underwent preoperative high-resolution manometry (HRM) and had evidence of GERD on ambulatory pH study. Cough, wheeze, and hoarseness were considered atypical symptoms. During preoperative and postoperative examinations, patients completed detailed foregut symptomatology questionnaires, using both 5-point Likert and 10-point visual analog scales (VAS) to document typical as well as atypical symptoms. Atypical symptom burden was calculated as a sum of VAS for the three atypical symptoms, termed the atypical score (ATS). HRM patterns were grouped into normal, spastic, and hypomotile. Statistical significance (p < 0.05) was determined using paired t-test, and analysis of variance with post hoc least significant difference (LSD).

Results: One hundred thirteen patients (age 49 ± 1.26 years, range 20-84 years, M:F 47:66) with mean follow-up of 28 ± 2.31 months (range 1-92 months) fulfilled inclusion criteria, having mean modified DeMeester score of 45.5 ± 2.78. Heartburn was noted in 84.1%, while atypical symptoms of some degree were reported by 92.0% (104 patients). Heartburn improved from a preoperative score of 7.1 ± 0.54 to 0.9 ± 0.24 after LARS, and ATS improved from 8.9 ± 0.71 to 2.2 ± 0.42. Significant improvements were noted for all atypical symptoms analyzed (p < 0.0001 for each). Improvement in atypical symptoms was least in the presence of hypomotility features on HRM (21.7% improvement), compared with normal motility (72.4%) and spastic features (83.9%). Preoperative atypical score (p < 0.0001) and esophageal hypomotility (p = 0.04) demonstrated a linear relationship with postoperative atypical score.

Conclusions: In an unselected cohort of patients undergoing LARS, atypical GERD symptoms improved as significantly as typical symptoms. Symptom improvement was significantly lower in the presence of esophageal hypomotility and with higher symptomatic state. Therefore, patients with severe atypical symptoms or hypomotile esophagus may not achieve the same clinical satisfaction from LARS.
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http://dx.doi.org/10.1007/s00464-011-1806-yDOI Listing
December 2011

Effect of repetitive loading on the mechanical properties of synthetic hernia repair materials.

J Am Coll Surg 2011 Sep 25;213(3):430-5. Epub 2011 Jun 25.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St Louis, MO, USA.

Background: Hernia repair materials undergo repeated loading while in the body, and the impact on mechanical properties is unknown. It was hypothesized that exposure to repetitive loading would lead to decreased tensile strength and increased strain, and that these differences would become more pronounced with greater loading and unloading sequences.

Study Design: Polypropylene, expanded polytetrafluoroethylene, composite barrier, and partially absorbable meshes were evaluated. Twenty specimens (7.5 × 7.5 cm) were prepared from each material. Five specimens were subjected to ball burst testing to determine baseline biomechanical properties. Cycles of 10, 100, and 1,000 loading sequences were also performed (n = 5 each).

Results: BardMesh (CR Bard/Davol), Dualmesh (WL Gore), and Prolene (Ethicon) exhibited significantly reduced tensile strength; BardMesh, Proceed (Ethicon), Prolene, ProLite (Atrium Medical), ProLite Ultra (Atrium Medical), and Ultrapro (Ethicon) exhibited significantly increased strain after exposure to 1,000 cycles compared with their baseline properties. BardMesh and Prolene demonstrated both reduced tensile strength and increased strain values after 1,000 cycles, suggesting that repetitive loading has the greatest effects on these materials. In addition, BardMesh and Prolene exhibited progressively worsening effects as the number of cycles was increased.

Conclusions: Deterioration of the tensile strength of the mesh or an increase in the ability of the mesh material to stretch (ie, increased strain values) could potentially lead to hernia recurrence or a poor functional result. However, the results of this study should not be interpreted to mean that hernia repair materials will fail in the body after only 10, 100, or 1,000 cycles. The conditions used in this study were more extreme than most physiologic scenarios and were intended as a pilot investigation into how the mechanical properties of hernia repair materials are affected by in vitro cyclic testing.
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http://dx.doi.org/10.1016/j.jamcollsurg.2011.05.018DOI Listing
September 2011

Laparoscopic fixation of biologic mesh at the hiatus with fibrin or polyethylene glycol sealant in a porcine model.

Surg Endosc 2011 Oct 19;25(10):3405-13. Epub 2011 May 19.

Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.

Background: The objective of this study was to determine the acute and chronic fixation strengths achieved by fibrin or polyethylene glycol (PEG) sealants to secure biologic mesh at the esophageal hiatus in a porcine model.

Methods: For this study, 32 female domestic pigs were divided into four groups of 8 each. The four groups respectively received acute fibrin sealant, acute PEG sealant, chronic fibrin sealant, and chronic PEG sealant. Laparoscopically, a 5.5 × 8.5-cm piece of Biodesign Surgisis Hiatal Hernia Graft (porcine small intestine submucosa) was oriented with the U-shaped cutout around the gastroesophageal junction and the short axis in the craniocaudal direction to simulate hiatal reinforcement with a biologic mesh. The mesh then was secured with 2 ml of either fibrin sealant or PEG sealant. The pigs in the acute groups were maintained alive for 2 h to allow for complete polymerization of the sealants, and the pigs in the chronic group were maintained alive for 14 days. After the pigs were euthanized, specimens of the mesh-tissue interface were subjected to lap shear testing to determine fixation strength, and hematoxylin and eosin (H&E) stained slides were evaluated for evidence of remodeling.

Results: No significant differences were observed between the acute and chronic fixation strengths or the remodeling characteristics of the two sealants. However, fixation strength increased significantly over time for both types of sealant. Evidence of remodeling also was significantly more pronounced in the chronic specimens than in the acute specimens.

Conclusions: This study demonstrated the feasibility of using fibrin or PEG sealants to secure biologic mesh at the hiatus in a porcine model.
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http://dx.doi.org/10.1007/s00464-011-1741-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826827PMC
October 2011

Histologic and biomechanical evaluation of crosslinked and non-crosslinked biologic meshes in a porcine model of ventral incisional hernia repair.

J Am Coll Surg 2011 May 23;212(5):880-8. Epub 2011 Mar 23.

Department of Surgery, Section of Minimally Invasive Surgery, Washington University School of Medicine, St Louis, MO, USA.

Background: The objective of this study was to evaluate the biomechanical characteristics and histologic remodeling of crosslinked (Peri-Guard, Permacol) and non-crosslinked (AlloDerm, Veritas) biologic meshes over a 12 month period using a porcine model of incisional hernia repair.

Study Design: Bilateral incisional hernias were created in 48 Yucatan minipigs and repaired after 21 days using an underlay technique. Samples were harvested at 1, 6, and 12 months and analyzed for biomechanical and histologic properties. The same biomechanical tests were conducted with de novo (time 0) meshes as well as samples of native abdominal wall. Statistical significance (p < 0.05) was determined using 1-way analysis of variance with a Fisher's least significant difference post-test.

Results: All repair sites demonstrated similar tensile strengths at 1, 6, and 12 months and no significant differences were observed between mesh materials (p > 0.05 in all cases). The strength of the native porcine abdominal wall was not augmented by the presence of the mesh at any of the time points, regardless of de novo tensile strength of the mesh. Histologically, non-crosslinked materials showed earlier cell infiltration (p < 0.01), extracellular matrix deposition (p < 0.02), scaffold degradation (p < 0.05), and neovascularization (p < 0.02) compared with crosslinked materials. However, by 12 months, crosslinked materials showed similar results compared with the non-crosslinked materials for many of the features evaluated.

Conclusions: The tensile strengths of sites repaired with biologic mesh were not impacted by very high de novo tensile strength/stiffness or mesh-specific variables such as crosslinking. Although crosslinking distinguishes biologic meshes in the short-term for histologic features, such as cellular infiltration and neovascularization, many differences diminish during longer periods of time. Characteristics other than crosslinking, such as tissue type and processing conditions, are likely responsible for these differences.
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http://dx.doi.org/10.1016/j.jamcollsurg.2011.01.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3782991PMC
May 2011

Biomechanical and histologic evaluation of fenestrated and nonfenestrated biologic mesh in a porcine model of ventral hernia repair.

J Am Coll Surg 2011 Mar;212(3):327-39

Department of Surgery, Washington University, St Louis, MO, USA.

Background: The purpose of this study was to compare tissue incorporation and adhesion characteristics of a novel fenestrated versus nonfenestrated crosslinked porcine dermal matrix (CPDM) (Bard CollaMend) in a porcine model of ventral hernia repair.

Study Design: Bilateral abdominal wall defects were created in 24 Yucatan minipigs, resulting in 48 defects, which were allowed to mature for 21 days. Twelve defects were repaired with fenestrated CPDM using a preperitoneal technique, 12 with fenestrated CPDM using an intraperitoneal technique, 12 with nonfenestrated CPDM using a preperitoneal technique, and 12 with nonfenestrated CPDM using an intraperitoneal technique. Half of the animals in the intraperitoneal group were euthanized after 1 month, and the other half after 3 months. Similarly, half of the animals in the preperitoneal group were euthanized after 1 month, and the other half after 6 months. Biomechanical testing and histologic evaluation were performed.

Results: Intraperitoneal placement of the CPDM products resulted in significantly greater adhesed area compared with preperitoneal placement (p < 0.05). Tissue ingrowth into preperitoneal fenestrated and nonfenestrated CPDM resulted in significantly greater incorporation strengths after 6 months compared with 1 month (p = 0.03 and p < 0.0001). Histologic analysis showed significantly greater cellular infiltration, extracellular matrix deposition, and neovascularization, with less fibrous encapsulation through the center of the fenestrations compared with all other sites evaluated, including nonfenestrated grafts.

Conclusions: Histologic findings revealed increased tissue incorporation at fenestration sites compared with nonfenestrated grafts regardless of implant location or time in vivo. However, preperitoneal placement resulted in greater incorporation strength, less adhesed area, and lower adhesion scores compared with intraperitoneal placement for both fenestrated and nonfenestrated CPDM.
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http://dx.doi.org/10.1016/j.jamcollsurg.2010.12.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3783002PMC
March 2011

Best resident poster award: evaluation of anastomotic techniques for laparoscopic resection of isolated small intestine pathology.

Am J Surg 2010 Dec;200(6):851-5

Department of Surgery, William Beaumont Army Medical Center, El Paso, TX, USA.

Background: The purpose of this study was to compare perioperative outcomes for intracorporeal versus extracorporeal anastomotic techniques for isolated laparoscopic small-intestine resection.

Methods: A retrospective database was created for all adult patients who underwent a laparoscopic segmental small-intestine resection. Patients with inflammatory bowel disease or requiring an ileocolectomy were excluded.

Results: Laparoscopic resection was performed in 52 patients (ratio of men:women, 30:22) with a mean age of 47 ± 21 years. A laparoscopic intracorporeal anastomosis was performed in 30 patients (58%), and an extracorporeal anastomosis was performed in 22 patients (42%). There was no difference in mean operating room time, estimated blood loss, perioperative complication rate, or length of stay between the 2 groups. Ten patients had a complication, and 5 patients experienced a Clavien grade II or greater complication.

Conclusions: Laparoscopic segmental small-bowel resection using either intracorporeal or extracorporeal anastomotic techniques is equally efficacious for pathology isolated to the small bowel.
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http://dx.doi.org/10.1016/j.amjsurg.2010.07.033DOI Listing
December 2010