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ABSTRACT: 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.
Surgical Endoscopy 02/2013; · 4.01 Impact Factor
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ABSTRACT: 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.
Surgical Endoscopy 08/2012; · 4.01 Impact Factor
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ABSTRACT: 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.
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.
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).
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.
Surgical Endoscopy 04/2012; 26(10):2767-78. · 4.01 Impact Factor
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ABSTRACT: 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.
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.
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).
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.
Surgical Endoscopy 04/2012; 26(10):2717-28. · 4.01 Impact Factor
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ABSTRACT: BackgroundThis study aimed to evaluate the clinical utility of routine barium esophagram after laparoscopic anterior esophageal myotomy
for achalasia.
MethodsThe records of 260 consecutive patients who underwent laparoscopic anterior esophageal myotomy for achalasia from May 1996
to August 2007 were reviewed from a prospective institutional review board–approved database. Data are given as mean±standard
deviation. Statistical significance (p<0.05) was determined using a two-tailed t-test and Fisher’s exact test.
ResultsRoutine protocol barium esophagrams performed for 236 patients a mean of 1±0.3days postoperatively were interpreted for
145 (61.4%) of the patients as normal flow of contrast after esophageal myotomy. There were no false-negative studies in this
group, and diet was initiated without incident at a mean of 1±0.2days. The time to the goal diet was 1.3±0.7 postoperative
days, and the mean postoperative time to discharge was 1.5±1days. Of the 236 patients, 91 (38.6%) had an abnormal barium
esophagram (contrast retention or pooling, delayed emptying). For this group, initiation of a diet was delayed for only six
(6.6%) patients. Two barium esophagrams (0.9%) interpreted as an esophageal leak were determined to be false-positives after
the one patient underwent negative exploratory laparoscopy and the other was observed clinically. In this group, diet was
initiated at a mean of 1.1±0.3days. The time to the goal diet was 1.4±0.7days, and the mean postoperative time to discharge
was 1.8±1.9days. The mean times to diet initiation, goal diet, and discharge were not significantly different (p≥0.14) between the normal and the abnormal barium esophagram groups. The sensitivity and specificity of an abnormal routine
barium esophagram after laparoscopic esophageal myotomy were, respectively, 100% and 62.0%, and the positive and negative
predictive values were 2.2% and 100%.
ConclusionsBecause of its poor positive predictive value, routine barium esophagram after laparoscopic anterior esophageal myotomy should
be used selectively in the immediate postoperative period after an uncomplicated procedure.
Surgical Endoscopy 04/2012; 23(3):606-610. · 4.01 Impact Factor
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ABSTRACT: BackgroundSerious complications of adrenalectomy are rare but the incidence may be underestimated if they occur outside major referral
centers. We report five cases of high-grade complications after adrenalectomy that have not been previously described.
MethodsThe records of five cases of adrenalectomy performed at outside hospitals were reviewed. Four cases were referred for management
of complications and one for medical-legal review. The nature of the adrenal lesion, operative approach, complication(s),
and subsequent clinical course and complication management were assessed. Both open adrenalectomy (OA) and laparoscopic adrenalectomy
(LA) cases were included.
ResultsOperative indications were pheochromocytoma (N=3), aldosteronoma (N=1), and a nonfunctioning 6-cm hypervascular mass (N=1). Complications of adrenalectomy included: case 1—complete transection of the porta hepatitis during right LA resulting
in hepatic failure requiring emergent liver transplantation; case 2—ligation of the hepatic artery during right OA resulting
in recurrent cholangitis and bile duct sclerosis requiring liver transplantation; case 3—ligation of the left ureter during
LA resulting in postoperative hydronephrosis and loss of renal function; case 4—loss of left kidney function after OA, likely
secondary to renal artery ligation ultimately requiring laparoscopic nephrectomy; case 5—LA of a normal adrenal gland for
a 6-cm hypervascular mass thought to be arising from the adrenal gland. Three-month postoperative imaging demonstrated a persistent
mass and the patient underwent hand-assisted laparoscopic nephrectomy for a left upper pole renal cell carcinoma that was
missed at the time of LA.
ConclusionDespite the generally low morbidity of adrenalectomy, serious and potentially life-threatening complications can occur. Surgeon
inexperience may be a factor in the occurrence of some of these complications which have not been previously described.
Surgical Endoscopy 04/2012; 23(1):97-102. · 4.01 Impact Factor
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ABSTRACT: 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.
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).
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).
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.
Journal of the American College of Surgeons 04/2012; 215(2):216-28. · 4.55 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
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.
Annals of surgery 03/2012; 255(3):595-604. · 7.90 Impact Factor
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Journal of the American College of Surgeons 11/2011; 213(5):692. · 4.55 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Surgical Endoscopy 09/2011; 26(2):566-75. · 4.01 Impact Factor
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Arthur Rawlings,
Nathaniel J Soper,
Brant Oelschlager,
Lee Swanstrom, Brent D Matthews,
Carlos Pellegrini,
Richard A Pierce,
Aurora Pryor,
Valeria Martin,
Margaret M Frisella,
Maria Cassera,
L Michael Brunt
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ABSTRACT: 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.
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.
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).
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.
Surgical Endoscopy 07/2011; 26(1):18-26. · 4.01 Impact Factor
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ABSTRACT: This study aimed to determine whether the strength and extensibility of hernia repair materials are negatively influenced by the application of helical titanium tacks.
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.
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.
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.
Surgical Endoscopy 07/2011; 25(12):3890-7. · 4.01 Impact Factor
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ABSTRACT: 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.
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).
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.
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.
Surgical Endoscopy 06/2011; 25(12):3852-8. · 4.01 Impact Factor
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ABSTRACT: 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.
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).
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.
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.
Journal of the American College of Surgeons 06/2011; 213(3):430-5. · 4.55 Impact Factor
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ABSTRACT: 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.
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.
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.
This study demonstrated the feasibility of using fibrin or PEG sealants to secure biologic mesh at the hiatus in a porcine model.
Surgical Endoscopy 05/2011; 25(10):3405-13. · 4.01 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Journal of the American College of Surgeons 03/2011; 212(3):327-39. · 4.55 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Journal of the American College of Surgeons 03/2011; 212(5):880-8. · 4.55 Impact Factor
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ABSTRACT: This study aimed to evaluate the acute and chronic fixation strength of fibrin sealant (FS) as an alternative method of fixation for laparoscopic ventral hernia repair (LVHR).
Representative mesh types for LVHR included one nonabsorbable barrier mesh (Composix) and three absorbable barrier meshes (Sepramesh, Proceed, and Parietex composite). Macroporous polypropylene mesh (Prolite Ultra) served as the control mesh. Three methods of fixation were used, namely, 0-polypropylene suture+FS (ARTISS 4 IU), FS alone (ARTISS), and tacks alone, to secure 3×4-cm pieces of mesh (10 of each combination) to the peritoneal surface of New Zealand white rabbit abdominal wall. After 2 h of incubation at 37 °C, specimens underwent acute testing. Subsequently, a chronic phase was completed using the aforementioned fixation methods (10 of each combination), in which two 4×4-cm pieces of mesh were secured intraperitoneally in each of 75 New Zealand white rabbits, which survived 8 weeks until they were sacrificed. A transparent grid overlay was used to measure the mesh and adhesion area. Adhesion tenacity was characterized using the Garrard adhesion scale. In both the acute and chronic samples, a 3×3-cm area of mesh-tissue interface underwent lap shear testing at a rate of 0.42 mm/s using a tensiometer (Instron 5542). The maximum load sustained by the mesh-tissue construct was recorded as the acute fixation strength in newtons (N). Data are given as means±standard error of the mean. Statistical significance (p<0.05) was determined using a one-way analysis of variance (ANOVA) with Fisher's least significant difference (LSD) posttest or a nonparametric Kruskal-Wallis test (adhesion scores).
The acute fixation strength was significantly greater for all the meshes secured with either suture+FS or tacks alone than for FS alone (p<0.001 for all comparisons). All the meshes except Proceed demonstrated greater acute fixation strength with suture+FS than with tacks alone (p≤0.016). Composix achieved greater acute fixation with suture+FS than all the other meshes (p≤0.022). Acute fixation with suture + FS was greater for Parietex Composite and ProLite Ultra than for Proceed (p≤0.015). When the animals were sacrificed, 48 of 50 meshes fixed with FS alone were insufficiently affixed to the abdominal wall, which may have resulted in hernia recurrence in a hernia model. The chronic fixation strength was greater for all the mesh types with either suture+FS or tacks only than with FS alone (p≤0.0005). The chronic fixation strength was greater with suture+FS than with tacks for Proceed and ProLite Ultra (p≤0.013). Neither mesh area nor adhesion tenacity differed significantly with any mesh/fixation method combination.
In a chronic rabbit model of LVHR, fixation strength with FS alone was inadequate for selected nonabsorbable and absorbable barrier-coated meshes. The acute and chronic fixation strengths of suture+FS were equivalent or superior to the fixation strength of tacks alone. Using a combination of suture and FS for mesh fixation in LVHR may provide adequate fixation while decreasing postoperative pain due to spiral titanium tacks. In this preclinical series, mesh secured to the peritoneal surface by FS alone may have led to early recurrence.
Surgical Endoscopy 02/2011; 25(2):604-12. · 4.01 Impact Factor
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ABSTRACT: For meshes to be used effectively for hernia repair, it is imperative that engineers and surgeons standardize the terminology and techniques related to physicomechanical evaluation of these materials. The objectives of this study were to propose standard techniques, perform physicomechanical testing, and classify materials commonly used for inguinal hernia repair.
Nine meshes were evaluated: 4 polypropylene, 1 polyester, 1 polytetrafluoroethylene, and 3 partially absorbable. Physical properties were determined through image analysis, laser micrometry, and density measurements. Biomechanical properties were determined through suture retention, tear resistance, uniaxial, and ball burst testing with specimens tested in 2 different orientations. A 1-way ANOVA with Tukey's post-test or a t-test were performed, with p < 0.05.
Significant differences were observed due to both mesh type and orientation. Areas of interstices ranged from 0.33 ± 0.01 mm² for ProLite (Atrium Medical Corp) and C-QUR Lite (Atrium Medical Corp) Large to 4.10 ± 0.06 mm² for ULTRAPRO (Ethicon), and filament diameters ranged from 99.00 ±8.1 μm for ProLite Ultra (Atrium Medical Corp) and C-QUR Lite Small to 338.8 ± 3.7 μm for Parietex Flat Sheet TEC (Covidien). These structural characteristics influenced biomechanical properties such as tear resistance and tensile strength. ProLite Ultra, C-QUR Lite Small, ULTRAPRO and INFINIT (WL Gore & Associates) did not resist tearing as effectively as the others. All meshes exhibited supraphysiologic burst strengths except INFINIT and ULTRAPRO.
Significant differences exist between the physicomechanical properties of polypropylene, polyester, polytetrafluoroethylene, and partially absorbable mesh prostheses commonly used for inguinal hernia repair. Orientation of the mesh was also shown to be critical for the success of meshes, particularly those demonstrating anisotropy.
Journal of the American College of Surgeons 01/2011; 212(1):68-79. · 4.55 Impact Factor
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ABSTRACT: The purpose of this study was to compare perioperative outcomes for intracorporeal versus extracorporeal anastomotic techniques for isolated laparoscopic small-intestine resection.
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.
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.
Laparoscopic segmental small-bowel resection using either intracorporeal or extracorporeal anastomotic techniques is equally efficacious for pathology isolated to the small bowel.
American journal of surgery 12/2010; 200(6):851-5. · 2.36 Impact Factor
