Biomedical subjects

Robert W O'Rourke

Publications and source records attributed to Robert W O'Rourke.

10 recordsLinked to original sources

PubMed2006

Incorporation of Nissen fundoplication in a rat model of duodenoesophageal reflux.

BACKGROUND: Few in vivo models of esophageal reflux and fundoplication suitable for the study of the pathogenesis of Barrett's esophagus and esophageal cancer exist. We describe a modification of a rat model of duodenoesophageal reflux that incorporates Nissen fundoplication and uses it to study the role of fundoplication in ameliorating esophageal reflux. METHODS: A previously described rat model of duodenoesophageal reflux was modified to include Nissen fundoplication. Reflux threshold (RT), defined as the gastric pressure required to cause gastroesophageal reflux during transgastric instillation of saline, was measured in 12 Sprague-Dawley rats at baseline, after cardiomyotomy with esophagogastroduodenal anastomosis (EGDA), after subsequent Nissen fundoplication, and, finally, after takedown of Nissen fundoplication (NF). RESULTS: Cardiomyotomy with EGDA induced no significant change in RT compared with baseline (mean RT +/- SD: 4.0 +/- 1.9 mmHg and 6.0 +/- 2.5 mmHg, respectively, p = 0.741). Nissen fundoplication led to a 14-fold increase in RT (56.4 +/- 18.2 mmHg) compared with cardiomyotomy. RT pressure reverted to baseline levels after NF takedown (4.7 +/- 2.9 mmHg, p < 0.001). Antegrade esophageal flow was demonstrated without an increase in distal esophageal pressure after NF. CONCLUSIONS: Nissen fundoplication creates a one-way antireflux mechanism that eliminates gastroesophageal reflux in this rat model. This modification of an in vivo model of duodenoesophageal reflux represents a unique opportunity to investigate the effect of NF on cardiomyotomy-induced reflux and distal esophageal exposure to duodenogastric refluxate, and could be useful in the study of the role of NF in preventing progression to BE and ECA.

Animals↗

PubMed2006

Perioperative morbidity associated with bariatric surgery: an academic center experience.

HYPOTHESIS: As the demand for bariatric surgery increases, it becomes increasingly important to define predictors of morbidity and mortality. We hypothesize that specific clinical variables predict postoperative morbidity after bariatric surgery. DESIGN, SETTING, AND PATIENTS: This is a retrospective review of 452 patients undergoing inpatient bariatric surgery at an academic tertiary care institution. INTERVENTIONS: Patients underwent open or laparoscopic gastric bypass or biliopancreatic diversion with duodenal switch at Oregon Health & Science University, Portland, from 2000 to 2003. Patient data were prospectively entered into a database. MAIN OUTCOME MEASURES: Postoperative morbidity and mortality were analyzed among all patients, and logistic regression was used to identify clinical predictors of morbidity. RESULTS: Major and minor morbidity rates were 10% and 13%, respectively; mortality was 0.9%. Age was associated with postoperative complications (odds ratio = 1.056 for each additional year). Duodenal switch was also associated with higher morbidity than gastric bypass (odds ratio = 2.149). Body mass index, sex, diabetes, surgical approach, and surgeon experience did not predict complications. CONCLUSIONS: Increased age is a predictor of complications after bariatric surgery. Duodenal switch is also associated with a higher morbidity rate than gastric bypass. Surgeons should caution older patients (>/=60 years) of a higher risk of postoperative complications, and a higher risk associated with duodenal switch. Large multicenter studies will be necessary to accurately define other clinical predictors of morbidity and mortality after bariatric surgery.

Age Factors↗

PubMed2006

A model for gastric banding in the treatment of morbid obesity: the effect of chronic partial gastric outlet obstruction on esophageal physiology.

OBJECTIVE: This work establishes an animal model for nonadjustable gastric banding and characterizes the effect of gastric banding on esophageal physiology. SUMMARY BACKGROUND DATA: Obstruction at the esophagogastric junction (EGJ) results in esophageal dilation and aperistalsis. Although laparoscopic gastric banding as a primary treatment of morbid obesity has been widely accepted, the effects of this therapy on esophageal function remain unknown. METHODS: Twenty-five opossums were randomly divided into sham (n = 5), EGJ band (n = 5), and gastric band (n = 15) groups. Gastric and EGJ bands were surgically placed, and esophageal manometry was performed prebanding, at 2-week intervals during the banding period (up to 14 weeks), and 2 and 4 weeks after band removal. RESULTS: Manometric measures were equivalent prior to banding in all groups. There were no changes in LES or esophageal pressures during the study period in the sham group. During banding, there was a 36% decrease in baseline mean resting lower esophageal sphincter pressure in the gastric band group (P = 0.003). Mean distal esophageal peristaltic pressure decreased from baseline by 36% in gastric band animals (P < 0.001). The incidence of esophageal motility disorder during the study period for sham, EGJ band, and gastric band groups, was 2.9%, 42.1%, and 31.3%, respectively (P = 0.001, P = 0.381, pairwise comparisons of gastric band vs. sham and gastric band versus EGJ groups, respectively). Immediately prior to band removal, the probability of an abnormal peristaltic sequence with each swallow was 1%, 38%, and 16% for sham, EGJ, and gastric band groups, respectively (P < 0.005, pairwise comparisons of band groups with sham). CONCLUSIONS: Nonadjustable gastric banding results in impaired esophageal body motility, a reduction in esophageal peristaltic pressure, and a reduction in resting lower esophageal sphincter pressure. These findings suggest that gastric banding causes esophageal outlet obstruction and subsequent decompensation of peristaltic function as well as a compromise of the native antireflux mechanism.

Animals↗

PubMed2006

Office-based unsedated small-caliber endoscopy is equivalent to conventional sedated endoscopy in screening and surveillance for Barrett's esophagus: a randomized and blinded comparison.

OBJECTIVES: A major limitation to screening and surveillance of Barrett's esophagus is the complexity, expense, and risk associated with sedation for upper endoscopy. This study examines the feasibility, accuracy, and patient acceptability of office-based unsedated endoscopy as an alternative. METHODS: Of 274 eligible adults scheduled for endoscopic screening for gastroesophageal reflux symptoms or surveillance of Barrett's esophagus at a tertiary care center, 121 underwent unsedated small-caliber endoscopy and conventional endoscopy in a randomized crossover study. The two procedures were compared with regard to histological detection of Barrett's esophagus and dysplasia and biopsy size. Patients answered questionnaires assessing the tolerability of the procedures. RESULTS: The prevalence of Barrett's esophagus was 26% using conventional endoscopy and 30% using unsedated endoscopy (P= 0.503). The level of agreement between the two approaches was "moderate" (kappa= 0.591). Each modality detected four cases of low-grade dysplasia with concordance on one case. The tissue samples collected with unsedated endoscopy were smaller than with conventional endoscopy (P < 0.001). The majority of subjects rated their experience with both procedures as being well tolerated with minimal or no difficulty. When asked which procedure they would prefer in the future, 71% (81/114) chose unsedated small-caliber endoscopy. CONCLUSIONS: Office-based unsedated small-caliber endoscopy is technically feasible, well tolerated, and accurate in screening for Barrett's esophagus, despite yielding a smaller biopsy specimen. This approach bears the potential to eliminate the infrastructure and cost required for intravenous sedation in this application.

Aged↗

PubMed2006

Unsedated small-caliber upper endoscopy: an emerging diagnostic and therapeutic technology.

Although conventional esophagogastroduodenoscopy has become widespread in its applications and availability, it is constrained by the requirement for patient sedation. This requirement contributes to morbidity, time lost from work, and additional resource utilization in personnel and facilities. Small-caliber endoscopy is an emerging technology that enables transnasal evaluation of the upper gastrointestinal tract in a unsedated patient. This procedure can be performed in a wider range of settings, including the clinic setting where a dedicated conscious sedation suite is not available and can be incorporated into the office visit. The applications of small-caliber endoscopy include general diagnostic upper endoscopy, screening and surveillance of Barrett esophagus, and intraoperative diagnostics or postoperative evaluation of the upper gastrointestinal tract. Therapeutic applications include the placement of nasoduodenal feeding tubes, esophageal pH catheters, and impedance catheters. When used in the sedated patient, small-caliber endoscopy can also facilitate esophageal stricture dilation and transnasal placement of a percutaneous endoscopic gastrostomy tube. This review discusses the techniques, equipment, and applications of small-caliber endoscopy of the upper gastrointestinal tract.

Catheterization↗

PubMed2006

Gastro-gastric fistula in the era of divided Roux-en-Y gastric bypass: strategies for prevention, diagnosis, and management.

Roux-en-Y gastric bypass (RYGBP) is a mainstay of bariatric surgical therapy. Gastro-gastric fistula (GGF) is an infrequent but potentially serious complication of gastric bypass, and diagnosis may be difficult. We report two patients who underwent RYGBP complicated by development of GGF who nevertheless achieved excellent, durable weight loss. The pathogenesis, diagnosis, prevention and management of GGF after RYGBP is reviewed. GGF may not result in poor weight loss after RYGBP and is not an absolute indication for surgical revision.

Adult↗

PubMed2004

Laparoscopic biliary reconstruction.

BACKGROUND: Biliary reconstruction represents a relatively untested frontier in laparoscopy. METHODS: Retrospective review of all patients who underwent laparoscopic biliary operations at Legacy Health System from 1998 to 2003. RESULTS: Seven patients underwent laparoscopic biliary reconstruction. Indications included benign calculous disease in 4 patients, benign stricture on 1 patient, choledochal cyst in 1 patient, and malignant biliary obstruction in 1 patient. Operations performed included choledochoduodenostomy, hepaticojejunostomy, stricturoplasty, choledochal cyst excision with hepaticojejunostomy, and cholecystojejunostomy. Median operative time was 300 minutes. Median hospital stay was 4 days. One perioperative complication of a bowel obstruction required reoperation. Median follow-up was 15 months. One patient died of metastatic cancer 8 months after surgery. All other patients are symptom free with no signs of stricture or recurrent biliary obstruction. CONCLUSIONS: Laparoscopic biliary reconstruction represents a viable treatment option in carefully selected patients.

Adult↗

PubMed2003

Extended transmediastinal dissection: an alternative to gastroplasty for short esophagus.

HYPOTHESIS: The significance of short esophagus and its impact on failure after laparoscopic Nissen fundoplication are unknown. Although patients with severe esophageal shortening that requires Collis gastroplasty comprise a small percentage of patients undergoing fundoplication, we hypothesize that patients with moderate esophageal shortening requiring extended mediastinal dissection make up a larger subgroup and that extended laparoscopic mediastinal dissection is a good treatment strategy for such patients. DESIGN AND SETTING: Retrospective comparative analysis in an academic and private practice-based tertiary referral center. PATIENTS: A total of 205 patients underwent laparoscopic Nissen fundoplication for gastroesophageal reflux disease or paraesophageal hernias over 4 years. Outcomes in patients requiring either a type I (<5 cm) or type II (>5 cm) mediastinal dissection were compared. INTERVENTIONS: Laparoscopic Nissen fundoplication with or without extended mediastinal dissection and esophageal physiology testing. MAIN OUTCOME MEASURES: Symptom assessments, operative reports, and outcomes were prospectively recorded on standardized data sheets. Postoperative symptom assessment and esophageal physiology testing were performed. RESULTS: A total of 133 (65%) of the 205 patients underwent type I dissection, and 72 (35%) of the 205 patients underwent type II dissection. Failure occurred in 15 (11%) of 133 patients and 6 (10%) of 72 patients, respectively. The presence of a large hiatal or paraesophageal hernia predicted the need for type II dissection. CONCLUSIONS: No difference was seen in failure rates between patients who required a type II dissection and those who did not. This finding suggests that aggressive application of laparoscopic transmediastinal dissection to obtain adequate esophageal length may reduce fundoplication failure in patients with esophageal shortening and provide a success rate similar to that of patients with normal esophageal length. More liberal application of Collis gastroplasty in these patients is not warranted.

Chi-Square Distribution↗

PubMed2002

Postoperative symptoms and failure after antireflux surgery.

BACKGROUND: Outcomes in patients having surgery for gastroesophageal reflux disease are most commonly determined by symptomatic assessment. Objective testing is usually reserved for symptomatic patients. HYPOTHESIS: To evaluate the relationship between symptomatic and objective outcomes after antireflux surgery. DESIGN: Retrospective analysis of prospectively collected data. SETTING: A tertiary care teaching hospital with a comprehensive esophageal physiology laboratory. INTERVENTIONS: A 360 degrees (Nissen) fundoplication or a 270 degrees (Toupet) posterior fundoplication was performed based on esophageal motility. Twenty-four-hour pH monitoring was used as a gold standard for assessing postoperative acid reflux. PATIENTS: Two hundred nine consecutive patients with preoperative and postoperative symptomatic and objective testing performed between January 1, 1996, and June 15, 2001. MAIN OUTCOME MEASURES: Data on preoperative and postoperative symptoms, DeMeester scores, and esophageal motility were prospectively collected. Objective testing was performed after at least 6 months. RESULTS: The preoperative median DeMeester score was 50.0 (interquartile [IQ] range, 30.3-87.0). One hundred eighty patients had a Nissen and 29 patients had a Toupet fundoplication. After a median postoperative interval of 7.7 months (IQ range, 6.7-9.5 months), 174 patients (83.3%) had normal DeMeester scores (median, 2.2; IQ range, 0.8-5.0; P<.001). Of 58 patients (27.7%) who had reflux symptoms after surgery, only 17 (29.3%) had abnormal DeMeester scores (median, 36.9; IQ range, 748.4-20.0; P =.001). Eighteen (11.9%) of the 151 asymptomatic patients had abnormal DeMeester scores (median, 32.5; IQ range, 22.2-57.5; P =.006). CONCLUSIONS: There is poor correlation between postoperative reflux symptoms and actual reflux (abnormal DeMeester scores). Surgeons must be careful to define their terms when reporting success or failure rates after antireflux surgery. Routine use of medical therapy for suppressing postoperative gastroesophageal reflux disease symptoms is not supported by these data, and postoperative therapy should be based on objective testing only.

Female↗

PubMedDate not supplied

Alterations in T-cell subset frequency in peripheral blood in obesity.

BACKGROUND: Obesity affects the regulation of immune and inflammatory responses. This study characterizes differences in peripheral blood lymphocyte phenotype in obese humans. METHODS: Frequencies of lymphocyte subsets among peripheral blood mononuclear cells were compared between 10 obese (BMI > or = 35) and 10 lean subjects, as determined by antibodies directed against cluster differentiation (CD) markers. RESULTS: Obese patients demonstrated an increased frequency of CD3+CD4+ T-cells (mean difference 12%, P=0.004), a decreased frequency of CD3+CD8+ T-cells (mean difference 9.4%, P=0.016) and an increased frequency of CD3+CD8+CD95+ T-cells (mean difference 13.3%, P=0.032). No other differences among T-cell or monocyte subsets were noted. CONCLUSIONS: Obesity is associated with alterations in frequencies of peripheral CD4+ and CD8+ T-cells and aberrations in the expression of CD95 among CD8+ T-cells. These data suggest both CD4+ and CD8+ T-cell compartments, as well as the regulation of CD95 expression on CD8+ T-cells, as targets for further study into obesity's effects on the immune system.

Adult↗