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Biomedical subjects

John G Hunter

Publications and source records attributed to John G Hunter.

At least 19 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

Simplifying minimally invasive transhiatal esophagectomy with the inversion approach: Lessons learned from the first 20 cases.

HYPOTHESIS: The laparoscopic transhiatal esophagectomy can be simplified and performed safely and effectively by using a novel esophageal inversion technique. DESIGN: Case series describing technique, initial experience, and learning curve with laparoscopic inversion esophagectomy. SETTING: Tertiary care university hospital and veteran's hospital. PATIENTS: Twenty consecutive patients with high-grade dysplasia (n = 16) and esophageal adenocarcinoma (n = 4). INTERVENTION: Laparoscopic inversion esophagectomy, a totally laparoscopic approach to transhiatal esophagectomy that incorporates distal to proximal inversion to improve mediastinal exposure and ease of dissection. MAIN OUTCOME MEASURES: Perioperative end points and complications, compared between the first and second groups of 10 patients. RESULTS: There were 19 men and 1 woman. Median operative time was 448 minutes. Median blood loss was 175 cm3. Median intensive care unit stay was 4 days, and median total hospital stay was 9 days. Overall anastomotic leak rate was 20%. Five patients developed an anastomotic stricture, all successfully managed with endoscopic dilation. There were 2 recurrent laryngeal nerve injuries, which resolved. There was no intraoperative or 30-day mortality. Between the first 10 consecutive cases and last 10 procedures, the incidence of anastomotic leak and stricture formation decreased from 30% to 10% and 40% to 10%, respectively. During this period, the number of lymph nodes harvested increased 9-fold, and duration of intensive care unit stay decreased from 8.00 to 2.50 days. CONCLUSIONS: Laparoscopic inversion esophagectomy is a safe procedure. The learning curve for the inversion approach is approximately 10 operations in the hands of esophageal surgeons with advanced laparoscopic expertise.

Adenocarcinoma↗
PubMed2006

The journal of the future is here today.

Scientific publishing has undergone a complete transformation in the last two decades. While the process of peer review may differ little from what it was during the last 50 years, electronic indexing, electronic access, and now electronic submission of scientific manuscripts has transformed the surgical journal in the last decade. In fact, the editorial office of the journal has contracted to a workstation, a fax machine, a telephone, and a storage locker for the aging paper records.

Internet↗
PubMed2006

Endoscopic measurement of cardia circumference as an indicator of GERD.

BACKGROUND: It is theorized that repeated gastric distention leads to dilatation of the cardia and the development of GERD. We hypothesize that cardia circumference correlates with the presence and the severity of GERD, and we developed software to measure cardia circumference from static endoscopic images. Our aims were to validate the software and to quantify cardia circumference along the spectrum of GERD. METHODS: Software-based measurements were compared with actual measurements in animal and mechanical models. A retrospective review of an endoscopic database and patient charts produced 273 subjects, grouped as follows: controls, GERD, < or = 3-cm Barrett's esophagus, or > 3-cm Barrett's esophagus. A blinded abstractor measured cardia circumference by using images from the database. RESULTS: Software and actual measurements correlated closely and were reproducible among observers. Median cardia circumference for each group was the following: control, 31.8 mm; GERD, 37.8 mm; < or = 3-cm Barrett's esophagus, 38.4 mm; and > 3-cm Barrett's esophagus, 45.0 mm (p < 0.001). By using 34.3 mm as a cutoff, cardia circumference was 85.3% sensitive and 89.6% specific for the diagnosis of GERD. CONCLUSIONS: There was a direct relationship between cardia circumference and the presence of GERD. This finding augments our understanding of the anatomic contributions of the esophagogastric junction in the pathogenesis of GERD. Cardia measurement may prove to be a useful diagnostic tool.

Animals↗
PubMed2006

EUS characteristics of Nissen fundoplication: normal appearance and mechanisms of failure.

BACKGROUND: In patients who develop symptoms after Nissen fundoplication, the precise mechanism of failure can be difficult to determine. Current testing modalities do not demonstrate sufficient anatomic detail to definitively determine the mechanism. This observational study establishes that EUS can determine fundoplication integrity and hiatal anatomic relationships after Nissen fundoplication. METHODS: EUS was performed on the native esophagogastric junction and after Nissen fundoplication in two swine. The EUS characteristics of a properly performed fundoplication were determined. Subsequently, complications of Nissen fundoplication were created, and EUS was performed on each. The EUS criteria of each mechanism of failure were defined. RESULTS: EUS provided sufficient axial resolution to distinguish the esophagus, the fundoplication, and the surrounding hiatal structures within a single image. US of the native esophagogastric junction discerned the length of intra-abdominal esophagus, esophagogastric junction, crura, and anterior hiatus, and, thus, the point of entry into the abdominal cavity. EUS of Nissen fundoplication revealed a 5-layered pattern in a 360 degree configuration. These layers represent the following: (1) the esophageal wall, (2) the space between the esophagus and the fundoplication, (3) the inner gastric wall of the fundoplication, (4) the gastric lumen, and (5) the outer gastric wall of the fundoplication. A slipped repair was identified by the presence of an echogenic gastric serosa within the fundoplication. A tight fundoplication results in attenuation of the gastric walls, thickening of the esophageal wall, and loss of the 5-layer pattern secondary to obliteration of the potential spaces of the gastric lumen. Dehiscence of the fundoplication was evidenced by a less than 360 degree 5-layer pattern. CONCLUSIONS: EUS of hiatal anatomic relationships is feasible and provides detailed information regarding the integrity and the position of a Nissen fundoplication. EUS may enable a precise determination of the anatomic causes of failure after antireflux surgery.

Animals↗
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↗
PubMed2005

Discovery.

Explore the source record for details and available documents.

Exploratory Behavior↗
PubMed2005

Forty-eight-hour pH monitoring increases sensitivity in detecting abnormal esophageal acid exposure.

Ambulatory 24-hour esophageal pH measurement is the standard for detecting abnormal esophageal acid exposure (AEAE), but it has a false negative rate of 15% to 30%. Wireless 48-hour pH monitoring (Bravo; Medtronic, Shoreview, MN) may allow more accurate detection of AEAE versus 24-hour pH monitoring. Forty-eight-hour wireless data were reviewed from 209 patients at three different tertiary care referral centers between 2003 and 2005. Manometric or endoscopic determination of the lower esophageal sphincter helped place the Bravo probe 5 to 6 cm above the lower esophageal sphincter. A total of 190 studies in 186 patients had sufficiently accurate data. There were 114 women and 72 men with an average age of 51 years. AEAE was defined by a Johnson-DeMeester score greater than 14.7 and was obtained in 115 of 190 studies (61%). Only 64 of 115 patients (56%) demonstrated AEAE for both days of the study, whereas 51 of 115 patients (44%) demonstrated AEAE in a single 24-hour period. There was no difference in the prevalence of AEAE on day 1 versus day 2 only (26% vs. 18%, P = .26). Compared with 24-hour alone data, 48-hour data showed 22% more patients with AEAE. Frequent day-to-day variability in patients with AEAE may be missed by a single 24-hour pH test. Forty-eight-hour pH testing may increase detection accuracy and sensitivity for AEAE by as much as 22%.

Female↗
PubMed2005

Utilization of the delay phenomenon improves blood flow and reduces collagen deposition in esophagogastric anastomoses.

OBJECTIVE: Complications of anastomotic healing are a common source of morbidity and mortality after esophagogastrostomy. The delay phenomenon is seen when a skin flap is partially devascularized in a staged procedure prior to its definitive placement, resulting in increased blood flow at the time of grafting. This effect may be applied to esophagogastrectomy, potentially reducing anastomotic complications. SUMMARY BACKGROUND DATA: The purpose of this investigation was to apply the delay principle to the gastrointestinal tract, investigate mechanisms by which it occurs and examine the effects of delay on anastomotic healing. METHODS: Thirty-seven opossums were assigned to Sham (n = 5), Immediate (n = 14), and Delay (n = 18) groups. Each underwent laparotomy and measurement of baseline gastric fundus blood flow. The Delay and Immediate animals underwent ligation of the left, right, and short gastric vessels and subsequent measurement of gastric fundus blood flow. The Delay group underwent repeat measurement of blood flow, esophagogastrectomy, gastric tubularization, and esophagogastrostomy 28 days after vessel ligation. The Immediate group completed the procedure immediately after vessel ligation. The anastomoses in both groups were harvested 32 days after esophagogastrostomy. The Sham group underwent blood flow measurement on initial laparotomy, followed by harvesting of esophagogastric junction 60 days later. Sections taken through the anastomoses were examined with trichrome-staining and immunohistochemistry (IHC) for actin. Collagen content of the gastric submucosa 5 mm below the anastomosis was quantified, and preservation of the muscularis propria and muscularis mucosa was determined histologically. Capillary content of the esophagogastric junction was quantified using IHC for vascular endothelium in the Delay and Sham groups. RESULTS: Blood flow decreased by 73% following vessel ligation in Delay and Immediate groups. The Delay group had over 3 times the gastric blood flow of the Immediate group at the time of anastomosis at 16 (interquartile range [IQR] 11-17) versus 5, (IQR 5-6) mL/min/100 g (P = 0.000003). Two Immediate animals developed anastomotic leak and died; the Delay group had no complications. Submucosal collagen content in Sham, Delay, and Immediate groups were 57% (IQR 52-62), 65% (IQR 57-72), and 71% (IQR 60-82), respectively (P = 0.0004). The median distance of full-thickness atrophy of the muscularis propria was 0.10 mm (IQR 0-0.60 mm) in the Delay group and 0.53 mm (IQR 0.03-0.80 mm) in the Immediate group (P = 0.346). Five percent of the Delay group had atrophy of the muscularis mucosa, whereas 19% of Immediate animals had atrophy of this layer (P = 0.023). Compared with the Sham group, all Delay animals developed dilation of the right gastroepiploic artery and vein. A median of 27 (IQR 23-33) capillaries per 20x field was observed in the Sham fundus and 38 (IQR 31-46) in the Delay fundus (P = 0.037). CONCLUSIONS: The delay effect is associated with both vasodilation and angiogenesis and results in increased blood flow to the gastric fundus prior to esophagogastric anastomosis. Animals undergoing delayed operations have less anastomotic collagen deposition and ischemic injury than those undergoing immediate resection. Clinical application of the delay effect in patients undergoing esophagogastrectomy may lead to a decreased incidence of leak and stricture formation.

Anastomosis, Surgical↗
PubMed2005

When fundoplication fails: redo?

OBJECTIVE: The largest series in the literature dealing with redo fundoplication was presented and published in 1999 and included 100 patients. Herein we update this initial series of 100, with 207 additional patients who have undergone redo fundoplication (n = 307). SUMMARY BACKGROUND DATA: Increasing numbers of patients are failing esophagogastric fundoplication and requiring redo procedures. Data regarding the nature of these failures have been scant. METHODS: Data on all patients undergoing foregut surgery are collected prospectively. Between 1991 and 2004, 307 patients underwent redo fundoplication for the management of anatomic complications or recurrent GERD. Statistical analysis was performed with multiple chi2 and Mann-Whitney U analyses, as well as ANOVA. RESULTS: Between 1991 and 2004, 1892 patients underwent primary fundoplication for GERD (1734) or paraesophageal hernia (158). Of these, 54 required redo fundoplication (2.8%). The majority of failures (73%) were managed within 2 years of the initial operation (P = 0.0001). The mechanism of failure was transdiaphragmatic wrap herniation in 33 of 54 (61%). In the 231 patients who underwent fundoplication elsewhere, 109 had transdiaphragmatic herniation (47%, P = NS). In this group of 285 patients, 22 (8%) required another redo (P = NS). The majority of the procedures were initiated laparoscopically (240/307, 78%), with 20 converted (8%). Overall mortality was 0.3%. CONCLUSIONS: Failure of fundoplication is unusual in experienced hands. Most are managed within 2 years of the initial operation. Wrap herniation has now become the most common mechanism of failure requiring redo. Redo fundoplication was successful in 93% of patients, and most could be safely handled laparoscopically.

Fundoplication↗
PubMed2005

Impact of a transfer center on interhospital referrals and transfers to a tertiary care center.

BACKGROUND: The partnership of faculty physicians and senior clinical hospital administrators in the decision to accept interhospital transfers has not been fully studied. Transfers to academic medical centers on the basis of economics have been of particular concern. OBJECTIVES: To evaluate the impact of joint decision making on transfer acceptance, and to evaluate the basis for decisions to transfer patients to an academic medical center. METHODS: This was a database study of requested adult interhospital transfers, excluding psychiatric transfers, occurring between January 1, 2003, and December 31, 2003, by using data from a computerized patient-tracking system. Where possible, comparisons with the prior calendar year (i.e., prior to implementation of the administrative review process) were made. Incidence of refusal to accept requested transfers and payer mix of transfer patients were the main outcomes of interest. RESULTS: More than 90% of the adult patients were transferred for conditions that required tertiary care or met Emergency Medical Treatment and Labor Act (EMTALA) requirements. The patient conditions that did not meet tertiary care needs included obstetric patients who did not have prenatal care, patients who had hand and facial trauma, and patients who weighed more than 300 pounds. The payer mix of transfer patients remained stable when using the administrator and physician team to determine acceptance of transfers. During the evaluation period, approximately 91,500 patients statewide lost some level of Medicaid coverage. CONCLUSIONS: The value of an administrator and physician team as partners in the interhospital transfer process was demonstrated. Active management of interhospital transfers supports transfer of patients who require tertiary care or who meet EMTALA criteria, thus conserving limited bed capacity and ensuring financial equity, while caring for the uninsured and underinsured patients throughout the state.

Adult↗
PubMed2004

Stapled-wedge Collis gastroplasty for the shortened esophagus.

BACKGROUND: Minimally invasive Collis gastroplasty is an established technique for managing the shortened esophagus. The purpose of this report is to describe our new technique, the wedge gastroplasty, and report the short-term outcomes. METHODS: All patients (n = 143) undergoing laparoscopic fundoplication from May 2000 to March 2001 were assessed intraoperatively for shortened esophagus. After mediastinal dissection, 15 patients with inadequate intraabdominal esophageal length underwent wedge gastroplasty. Preoperative symptoms, operative times, and short-term outcomes were evaluated. RESULTS: Mean operative time was 184 +/- 36 minutes (range 138 to 258). There was 1 cervical esophageal tear from bougie passage and no other minor or major complications. At 6 weeks, there was more improvement in esophageal symptoms compared with extraesophageal symptoms. CONCLUSIONS: Wedge gastroplasty is effective in decreasing symptoms in patients with shortened esophagus and takes less time to perform than other gastroplasty techniques. Further study is needed to assess long-term outcomes.

Adult↗
PubMed2004

Laryngopharyngeal reflux symptoms better predict the presence of esophageal adenocarcinoma than typical gastroesophageal reflux symptoms.

OBJECTIVE: To determine whether the presence of laryngopharyngeal reflux symptoms is associated with the presence of esophageal adenocarcinoma (EAC). BACKGROUND: Most patients diagnosed with EAC have incurable disease at the time of detection. The majority of these patients are unaware of the presence of Barrett's esophagus prior to cancer diagnosis and many do not report typical symptoms of gastroesophageal reflux disease (GERD). This suggests that the current GERD symptom-based screening paradigm may be inadequate. Data support a causal relation between complicated GERD and laryngopharyngeal reflux symptoms. We theorize that laryngopharyngeal reflux symptoms are not recognized expeditiously, resulting in chronic esophageal injury and an unrecognized progression of Barrett's esophagus to EAC. METHODS: This is a case-comparison (control) study. Cases were patients diagnosed with EAC (n = 63) between 1997 and 2002. Three comparison groups were selected: 1) Barrett's esophagus patients without dysplasia (n = 50), 2) GERD patients without Barrett's esophagus (n = 50), and 3) patients with no history of GERD symptoms or antisecretory medication use (n = 56). The risk factors evaluated included demographics, medical history, lifestyle variables, and laryngopharyngeal reflux symptoms. Typical GERD symptoms and antisecretory medication use were recorded. Multivariate analysis of demographics, comorbid risk factors, and symptoms was performed with logistic regression to provide odds ratios for the probability of EAC diagnosis. RESULTS: The prevalence of patients with laryngopharyngeal reflux symptoms was significantly greater in the cases than comparison groups (P = 0.0005). The prevalence of laryngopharyngeal reflux symptoms increased as disease severity progressed from the non-GERD comparison group (19.6%) to GERD (26%), Barrett's esophagus (40%), and EAC patients (54%). Symptoms of GERD were less prevalent in cases (43%) when compared with Barrett's esophagus (66%) and GERD (86%) control groups (P < 0.001). Twenty-seven percent (17 of 63) of EAC patients never had GERD or laryngopharyngeal reflux symptoms. Fifty-seven percent of EAC patients presented without ever having typical GERD symptoms. Chronic cough, diabetes, and age emerged as independent risk factors for the development of EAC. CONCLUSIONS: Symptoms of laryngopharyngeal reflux are more prevalent in patients with EAC than typical GERD symptoms and may represent the only sign of disease. Chronic cough is an independent risk factor associated with the presence of EAC. Addition of laryngopharyngeal reflux symptoms to the current Barrett's screening guidelines is warranted.

Adenocarcinoma↗