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Dive into the research topics where Rodney J. Mason is active.

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Featured researches published by Rodney J. Mason.


Annals of Surgery | 1997

Inflammation and specialized intestinal metaplasia of cardiac mucosa is a manifestation of gastroesophageal reflux disease.

Stefan Öberg; Jeffrey H. Peters; Tom R. DeMeester; Para Chandrasoma; Jeffrey A. Hagen; Adrian P. Ireland; Manfred P. Ritter; Rodney J. Mason; Peter F. Crookes; Cedric G. Bremner

OBJECTIVE The purpose of the study was to test the hypothesis that cardiac mucosa, carditis, and specialized intestinal metaplasia at an endoscopically normal-appearing cardia are manifestations of gastroesophageal reflux disease. SUMMARY BACKGROUND DATA In the absence of esophageal mucosal injury, the diagnosis of gastroesophageal reflux disease currently rests on 24-hour pH monitoring. Histologic examination of the esophagus is not useful. The recent identification of specialized intestinal metaplasia at the cardia, along with the observation that it occurs in inflamed cardiac mucosa, led the authors to focus on the type and condition of the mucosa at the gastroesophageal junction and its relation to gastroesophageal reflux disease. METHODS Three hundred thirty-four consecutive patients with symptoms of foregut disease, no evidence of columnar-lined esophagus, and no history of gastric or esophageal surgery were evaluated by 1) endoscopic biopsies above, at, and below the gastroesophageal junction; 2) esophageal motility; and 3) 24-hour esophageal pH monitoring. The patients were divided into groups depending on the histologic presence of cardiac epithelium with and without inflammation or associated intestinal metaplasia. Markers of gastroesophageal reflux disease were compared between groups (i.e., lower esophageal sphincter characteristics, esophageal acid exposure, the presence of endoscopic erosive esophagitis, and hiatal hernia). RESULTS When cardiac epithelium was found, it was inflamed in 96% of the patients. The presence of cardiac epithelium and carditis was associated with deterioration of lower esophageal sphincter characteristics and increased esophageal acid exposure. Esophagitis occurred more commonly in patients with carditis whose sphincter, on manometry, was structurally defective. Specialized intestinal metaplasia at the cardia was only seen in inflamed cardiac mucosa, and its prevalence increased both with increasing acid exposure and with the presence of esophagitis. CONCLUSION The findings of cardiac mucosa, carditis, and intestinal metaplasia in an endoscopically normal-appearing gastroesophageal junction are histologic indicators of gastroesophageal reflux disease. These findings may be among the earliest signs of gastroesophageal reflux and contribute to the authors understanding of the pathophysiology of the disease process.


Annals of Surgery | 2005

Laparoscopic Versus Open Appendectomy: A Prospective Randomized Double-Blind Study

Namir Katkhouda; Rodney J. Mason; Shirin Towfigh; Anna Gevorgyan; Rahila Essani

Summary Background Data:The value of laparoscopy in appendicitis is not established. Studies suffer from multiple limitations. Our aim is to compare the safety and benefits of laparoscopic versus open appendectomy in a prospective randomized double blind study. Methods:Two hundred forty-seven patients were analyzed following either laparoscopic or open appendectomy. A standardized wound dressing was applied blinding both patients and independent data collectors. Surgical technique was standardized among 4 surgeons. The main outcome measures were postoperative complications. Secondary outcome measures included evaluation of pain and activity scores at base line preoperatively and on every postoperative day, as well as resumption of diet and length of stay. Activity scores and quality of life were assessed on short-term follow-up. Results:There was no mortality. The overall complication rate was similar in both groups (18.5% versus 17% in the laparoscopic and open groups respectively), but some early complications in the laparoscopic group required a reoperation. Operating time was significantly longer in the laparoscopic group (80 minutes versus 60 minutes; P = 0.000) while there was no difference in the pain scores and medications, resumption of diet, length of stay, or activity scores. At 2 weeks, there was no difference in the activity or pain scores, but physical health and general scores on the short-form 36 (SF36) quality of life assessment forms were significantly better in the laparoscopic group. Appendectomy for acute or complicated (perforated and gangrenous) appendicitis had similar complication rates, regardless of the technique (P = 0.181). Conclusions:Unlike other minimally invasive procedures, laparoscopic appendectomy did not offer a significant advantage over open appendectomy in all studied parameters except quality of life scores at 2 weeks. It also took longer to perform. The choice of the procedure should be based on surgeon or patient preference.


Annals of Surgery | 1999

Laparoscopic management of benign solid and cystic lesions of the liver.

Namir Katkhouda; Michael Hurwitz; Jean Gugenheim; Eli Mavor; Rodney J. Mason; Donald J. Waldrep; Raymond T. Rivera; Mudjianto Chandra; Guilherme M. Campos; Steven Offerman; Andrew Trussler; Pascal Fabiani; Jean Mouiel

OBJECTIVE The authors present their experience in the laparoscopic management of benign liver disease. The aim of the study is to analyze technical feasibility and evaluate immediate and long-term outcome. SUMMARY BACKGROUND DATA Indications for the laparoscopic management of varied abdominal conditions have evolved. Although the minimally invasive treatment of liver cysts has been reported, the laparoscopic approach to other liver lesions remains undefined. METHODS Between September 1990 and October 1997, 43 patients underwent laparoscopic liver surgery. There were two groups of benign lesions: cysts (n = 31) and solid tumors (n = 12). Indications were solitary giant liver cysts (n = 16), polycystic liver disease (n = 9), hydatid cyst (n = 6), focal nodular hyperplasia (n = 3), and adenoma (n = 9). Only solid tumors, hydatid cysts, and patients with polycystic disease and large dominant cysts located in anterior liver segments were included. All giant solitary liver cysts were considered for laparoscopy. Patients with cholangitis, cirrhosis, and significant cardiac disease were excluded. Data were collected prospectively. RESULTS The procedures were completed laparoscopically in 40 patients. Median size was 4 cm for solid nodules and 14 cm for solitary liver cysts. Conversion occurred in three patients (7%), for bleeding (n = 2) and impingement of a solid tumor on the inferior vena cava (n = 1). The median operative time was 179 minutes. All solitary liver cysts were fenestrated in less than 1 hour. There were no deaths. Complications occurred in 6 cases (14.1%). Two hemorrhagic and two infectious complications were noted after management of hydatid cysts. There were no complications after resection of solid tumors. Three patients received transfusions (7%). The median length of stay was 4.7 days. Median follow-up was 30 months. There was no recurrence of solitary liver or hydatid cysts. One patient with polycystic disease had symptomatic recurrent cysts at 6 months requiring laparotomy. CONCLUSION Laparoscopic liver surgery can be accomplished safely in selected patients with small benign solid tumors located in the anterior liver segments and giant solitary cysts. The laparoscopic management of polycystic liver disease should be reserved for patients with a limited number of large, anteriorly located cysts. Hydatid disease is best treated through an open approach.


Annals of Surgery | 2001

Use of Fibrin Sealant for Prosthetic Mesh Fixation in Laparoscopic Extraperitoneal Inguinal Hernia Repair

Namir Katkhouda; Eli Mavor; Melanie H. Friedlander; Rodney J. Mason; Milton Kiyabu; Steven W. Grant; Kranti Achanta; Erlinda L. Kirkman; Krishna Narayanan; Rahila Essani

ObjectiveTo evaluate the efficacy of mesh fixation with fibrin sealant (FS) in laparoscopic preperitoneal inguinal hernia repair and to compare it with stapled fixation. Summary Background DataLaparoscopic hernia repair involves the fixation of the prosthetic mesh in the preperitoneal space with staples to avoid displacement leading to recurrence. The use of staples is associated with a small but significant number of complications, mainly nerve injury and hematomas. FS (Tisseel) is a biodegradable adhesive obtained by a combination of human-derived fibrinogen and thrombin, duplicating the last step of the coagulation cascade. It can be used as an alternative method of fixation. MethodsA prosthetic mesh was placed laparoscopically into the preperitoneal space in both groins in 25 female pigs and fixed with either FS or staples or left without fixation. The method of fixation was chosen by randomization. The pigs were killed after 12 days to assess early graft incorporation. The following outcome measures were evaluated: macroscopic findings, including graft alignment and motion, tensile strength between the grafts and surrounding tissues, and histologic findings (fibrous reaction and inflammatory response). ResultsThe procedures were completed laparoscopically in 49 sites. Eighteen grafts were fixed with FS and 16 with staples; 15 were not fixed. There was no significant difference in graft motion between the FS and stapled groups, but the nonfixed mesh had significantly more graft motion than in either of the fixed groups. There was no significant difference in median tensile strength between the FS and stapled groups. The tensile strength in the nonfixed group was significantly lower than the other two groups. FS triggered a significantly stronger fibrous reaction and inflammatory response than in the stapled and control groups. No infection related to method of fixation was observed in any group. ConclusionAn adequate mesh fixation in the extraperitoneal inguinal area can be accomplished using FS. This method is mechanically equivalent to the fixation achieved by staples and superior to nonfixed grafts. Biologic soft fixation with FS will prevent early graft migration and will avoid the complications associated with staple use.


Annals of Surgery | 2002

Vagal-Sparing Esophagectomy: A More Physiologic Alternative

Farzaneh Banki; Rodney J. Mason; Steven R. DeMeester; Jeffrey A. Hagen; Nagammapudur S. Balaji; Peter F. Crookes; Cedric G. Bremner; Jeffrey H. Peters; Tom R. DeMeester

ObjectiveTo evaluate the function of the vagal nerves and the gastric reservoir after vagal-sparing esophagectomy. Summary Background DataEsophagectomy as currently performed includes division of the vagal nerves and surgical alteration of the stomach, with attendant postoperative dumping, diarrhea, reduced meal capacity, and weight loss. Vagal-sparing esophagectomy has been introduced as a technique for removal of the esophagus while preserving the vagal nerves and gastric reservoir. The procedure is touted as having a low morbidity and is applicable to patients with end-stage benign or early malignant disease. MethodsA random sample of 15 patients at a median of 20 months after a vagal-sparing esophagectomy was compared to 23 asymptomatic normal subjects; 10 randomly selected patients, 29 months after esophagogastrectomy with colon interposition; and 10 randomly selected patients, 47 months after standard esophagectomy with gastric pull-up. Gastric mucosal acidification was tested with Congo red staining. Vagal secretory function was measured by gastric acid output and pancreatic polypeptide response to sham feeding. Vagal motor function was assessed by a technetium gastric emptying scan and a questionnaire to evaluate dumping and diarrhea. Gastric reservoir function was evaluated by measuring meal capacity and postoperative changes in body mass index. ResultsVagal-sparing esophagectomy preserved the function of the vagi, as evident by an increase in gastric acid output, a rise in serum pancreatic polypeptide following sham feeding, and preservation of normal postoperative gastric emptying in 70% of the patients. After vagal-sparing esophagectomy, patients were free of dumping and diarrhea and were analogous to normal subjects in meal capacity but had a slight reduction in the speed of eating. ConclusionsVagal-sparing esophagectomy preserves gastric secretory, motor, and reservoir function. Postoperatively, patients have normal alimentation, bowel regulation, and no weight loss. It is an ideal procedure for patients with end-stage benign disease, Barrett’s esophagus with high-grade dysplasia, or esophageal carcinoma limited to the lamina propria.


American Journal of Surgery | 2000

Intraabdominal abscess rate after laparoscopic appendectomy

Namir Katkhouda; Melanie H. Friedlander; Steven W. Grant; Kranthi K Achanta; Rahila Essani; Peter Paik; George C. Velmahos; Guillermo Campos; Rodney J. Mason; Eli Mavor

BACKGROUND Studies suggest increased intraabdominal abscess (IA) rates following laparoscopic appendectomy (LA), especially for perforated appendicitis. Consequently, an open approach has been advocated. The aim of our study is to compare IA rates following LA performed by a laparoscopic surgery and a general surgical service within the same institution. METHODS Data of LA patients treated at Los Angeles County-University of Southern California (LAC-USC) Medical Center between March 1992 and June 1997 were reviewed. The main outcome measure was postoperative IA. RESULTS In all, 645 LA were reviewed. A total of 413 LA (285 acute, 61 gangrenous, 67 perforated appendicitis) were performed by three general surgical services (10 attendings). Ten abscesses occurred postoperatively (2.4%), 6 with perforated appendicitis. After the laparoscopic service was introduced, 232 standardized LA (126 acute, 46 gangrenous, 60 perforated) were performed by two attendings. One IA occurred (gangrenous appendicitis). The IA rate for perforated appendicitis was significantly lower on the laparoscopic service (P = 0.025). There was no difference in IA rates for acute and gangrenous appendicitis. There was no mortality in either group. CONCLUSION IA rate following LA for perforated appendicitis was significantly reduced on the laparoscopic service. Mastery of the learning curve and addition of specific surgical techniques explained this improved result. Therefore, laparoscopic appendectomy for complicated appendicitis may not be contraindicated, even for perforated appendicitis.


Surgical Infections | 2008

Surgery for Appendicitis: Is It Necessary?

Rodney J. Mason

BACKGROUND Appendectomy for acute appendicitis is an effective, universally accepted procedure performed more than 300,000 times annually in the United States. It is generally believed that appendicitis progresses invariably from early inflammation to later gangrene and perforation, and that appendectomy is required for surgical source control. Although non-operative management with antibiotics of uncomplicated diverticulitis, salpingitis, and neonatal enterocolitis is now established, the non-operative management of appendicitis remains largely unexplored. METHODS Systematic review of published literature and derived expert opinion. RESULTS Clinical, epidemiologic, radiologic, and pathologic evidence is presented for spontaneous resolution of uncomplicated acute appendicitis. The pathogenesis of appendicitis is reviewed with specific consideration of the role of bacterial infection in the pathogenesis. Evidence is also provided documenting the clinical success of non-operative management. CONCLUSIONS Appendectomy may not be necessary for the majority of patients with acute uncomplicated appendicitis, as many patients resolve spontaneously and others may be treatable with antibiotics alone. However, the supporting documentation is scant and of poor quality. A randomized, prospective trial of non-operative management versus early appendectomy of acute uncomplicated appendicitis corroborated by radiologic imaging is called for.


Surgical Endoscopy and Other Interventional Techniques | 2006

Laparoscopic appendectomy significantly reduces length of stay for perforated appendicitis

Shirin Towfigh; F. Chen; Rodney J. Mason; Namir Katkhouda; L. Chan; Thomas V. Berne

IntroductionThough ruptured appendicitis is not a contraindication to laparoscopic appendectomy (LA), most surgeons have not embraced LA as the first-line approach to ruptured appendicitis. In fact, in 2002, the Cochrane Database Review concluded: 1) the clinical effects of LA are “small and of limited clinical relevance,” and 2) the effects of LA in perforated appendicitis require further study.ObjectiveTo study the effects of LA vs open appendectomy (OA) among adults with appendicitis.MethodsIn 2003, 272 adults underwent appendectomy at a large County hospital, and were enrolled in a prospective clinical pathway that detailed their hospital course from time of diagnosis to discharge. Data included patient demographics, time elapse from diagnosis to surgery, surgical technique (LA vs. OA), operative diagnosis (acute vs perforated appendicitis) and post-operative length of stay (LOS).ResultsComplete data was obtained for 264 (97%) patients. Patient demographics were similar in the LA and OA groups (p > 0.05). Patients with LA had a significantly shorter LOS than OA by 1.6 days (p < 0.05). This LOS was significantly shorter among those with ruptured appendicitis vs. non-ruptured appendicitis (2.0 days vs. 0.3 day reduction, p = 0.0357). Rank-order multiple regression analysis, controlling for all other factors, showed laparoscopy to have a significant effect on postoperative LOS in all appendicitis cases, especially ruptured appendicitis.ConclusionsThe two-day reduction in LOS among those with ruptured appendicitis who underwent LA was significant enough to overcome the smaller benefit of LA in acute appendicitis. From a hospital utilization point of view, LA should be considered as the first-line approach for all patients with appendicitis.


Annals of Surgery | 2011

Laparoscopic versus open anterior abdominal wall hernia repair: 30-day morbidity and mortality using the ACS-NSQIP database.

Rodney J. Mason; Ashkan Moazzez; Helen J. Sohn; Thomas V. Berne; Namir Katkhouda

Objective:To compare short-term outcomes after laparoscopic and open abdominal wall hernia repair. Methods:Using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database (2005–2009), 71,054 patients who underwent an abdominal wall hernia repair were identified (17% laparoscopic, 83% open). Laparoscopic and open techniques were compared. Regression models and nonparametric 1:1 matching algorithms were used to minimize the influence of treatment selection bias. The association between surgical approach and risk-adjusted adverse event rates after abdominal wall hernia repair was determined. Subgroup analysis was performed between inpatient/outpatient surgery, strangulated/reducible, and initial/recurrent hernias as well as between umbilical, incisional and other ventral hernias. Results:Patients undergoing laparoscopic repair were less likely to experience an overall morbidity (6.0% vs. 3.8%; odds ratio [OR], 0.62; 95% confidence interval [CI], 0.56–0.68) or a serious morbidity (2.5% vs. 1.6%; OR, 0.61; 95% CI, 0.52–0.71) compared to open repair. Analysis using multivariate adjustment and patient matching showed similar findings. Mortality rates were the same. Laparoscopically repaired strangulated and recurrent hernias, had a significantly lower overall morbidity (4.7% vs. 8.1%, P < 0.0001 and 4.1% vs. 12.2%, P < 0.0001, respectively). Significantly lower overall morbidity was also noted for the laparoscopic approach when the hernias were categorized into umbilical (1.9% vs. 3.0%, P = 0.009), ventral (3.9% vs. 6.3%, P < 0.0001), and incisional (4.3% vs. 9.1%, P < 0.0001). No differences were noted between laparoscopic and open repairs in patients undergoing outpatient surgery, when the hernias were reducible. Conclusion:Laparoscopic hernia repair is infrequently used and associated with lower 30-day morbidity, particularly when hernias are complicated.


Surgical Endoscopy and Other Interventional Techniques | 2002

Endoscopic augmentation of the cardia with a biocompatible injectable polymer (Enteryx) in a porcine model

Rodney J. Mason; Michael W. Hughes; Glen A. Lehman; G Chiao; Jacques Devière; David Silverman; Tom R. DeMeester; J. H. Peters

Background: Endoscopic approaches to restore the gastroesophageal barrier in patients with gastroesophageal reflux disease (GERD) are presently undergoing clinical trial. The aim of the study was to demonstrate the feasibility, durability, safety, and antireflux efficacy following augmentation of the cardia with a biocompatible injectable polymer (Enteryx). Methods: Augmentation was performed in 12 Yucatan mini-pigs. The cardia was injected circumferentially with 1–1.5 ml of Enteryx at three or four sites. Four groups of three animals each were killed at 2, 6, 12, and 24 weeks following augmentation. Gastrointestinal endoscopy and esophageal manometry were performed preoperatively and postoperatively. Competency was determined as the intragastric pressure (yield pressure) and volume (yield volume) needed during gastric distension with air and water to result in equalization of gastric and esophageal pressure. Comparisons were made with a group of noninjected animals (n = 6). Results: All animals had a normal eating pattern; none showed any evidence of vomiting or regurgitation. The median injection volume was 4 ml (range, 1–8). At autopsy, implants were found in 83% of the animals. Intramuscular placement of the implant was durable, whereas sloughing occurred if the implant was placed submucosally. The mechanical properties of sphincter length and pressure were unaffected by the injection. The median yield pressure of the animals that survived for >6 weeks (21.4 mmHg) was significantly greater (p = 0.049) than the animals that survived for <6 weeks (4.5 mmHg) and greater (p = 0.054) than the control animals (9.1 mmHg), suggesting that the healing process was associated with reduced distensibility of the cardia. Conclusions: Augmentation of the cardia with an injectable polymer (Enteryx) is simple, safe, and durable. Early studies suggest that alteration in the distensibility and geometry of the gastroesophageal junction may provide antireflux protection.

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Tom R. DeMeester

University of Southern California

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Namir Katkhouda

University of Southern California

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Cedric G. Bremner

University of the Witwatersrand

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Jeffrey A. Hagen

University of Southern California

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Peter F. Crookes

University of Southern California

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Steven R. DeMeester

University of Southern California

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Ashkan Moazzez

University of Southern California

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Farzaneh Banki

University of Texas Health Science Center at Houston

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Helen J. Sohn

University of Southern California

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