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Biomedical subjects

A Chak

Publications and source records attributed to A Chak.

At least 19 recordsLinked to original sources
PubMed2006

Diaphragm pacing with natural orifice transluminal endoscopic surgery: potential for difficult-to-wean intensive care unit patients.

BACKGROUND: Up to 50% of the patients in the intensive care unit (ICU) require mechanical ventilation, with 20% requiring the use of a ventilator for more than 7 days. More than 40% of this time is spent weaning the patient from mechanical ventilation. Failure to wean from mechanical ventilation can in part be attributable to rapid onset of diaphragm atrophy, barotrauma, posterior lobe atelectasis, and impaired hemodynamics, which are normally improved by maintaining a more natural negative chest pressure. The authors have previously shown that laparoscopic implantation of a diaphragm pacing system benefits selected patients. They now propose that an acute ventilator assist with interventional neurostimulation of the diaphragm in the ICU is feasible and could facilitate the weaning of ICU patients from mechanical ventilation. Natural orifice transluminal endoscopic surgery (NOTES) has the potential to expand the benefits of the diaphragm pacing system to this acute patient population by allowing it to be performed at the bedside similarly to insertion of the common gastrostomy tube. This study evaluates the feasibility of this approach in a porcine model. METHODS: Pigs were anesthetized, and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery, and balloon dilation. The diaphragm was mapped using a novel endoscopic electrostimulation catheter to locate the motor point (where stimulation provides complete contraction of the diaphragm). An intramuscular electrode then was placed at the motor point with a percutaneous needle. The gastrotomy was managed with a gastrostomy tube. RESULTS: Four pigs were studied, and the endoscopic mapping instrument was able to map the diaphragm to identify the motor point. In one animal, a percutaneous electrode was placed into the motor point under transgastric endoscopic visualization, and the diaphragm could be paced in conjunction with mechanical ventilation. CONCLUSIONS: These animal studies demonstrate the feasibility of transgastric mapping of the diaphragm and implantation of a percutaneous electrode for therapeutic diaphragmatic stimulation.

Animals↗
PubMed2004

Endoscopic ultrasonography.

Increasing research related to endoscopic ultrasonography is published every year. A welcome trend towards outcomes-oriented research, evaluating the impact of endoscopic ultrasonography on patient management, is continuing. As experience regarding the safety and efficacy of endosonography-guided fine-needle aspiration in different clinical settings accumulates, this procedure is rapidly becoming a key component of endoscopic ultrasonography. Although promising developments in the fields of guided tissue sampling and image acquisition and analysis are being reported, innovative technical ideas need to be incorporated into the existing endoscopic ultrasound technology to take it to the next level of applications, such as endosurgery.

Biopsy, Fine-Needle↗
PubMed2004

The No Endosonographic Detection of Tumor (NEST) Study: a case series of pancreatic cancers missed on endoscopic ultrasonography.

BACKGROUND AND STUDY AIMS: The purpose of this study was to identify possible associated factors that may have contributed to failure to detect a pancreatic neoplasm during endoscopic ultrasound (EUS) examinations by experienced endosonographers. PATIENTS AND METHODS: A multicenter retrospective study was organized, and 20 cases of pancreatic neoplasms missed by nine experienced endosonographers were identified. Careful analysis of each case was carried out to identify the factors that might have led to the missed diagnosis on EUS. RESULTS: Twelve patients with a missed pancreatic neoplasm had EUS features of chronic pancreatitis. Other factors that might have increased the likelihood of a false-negative EUS examination included a diffusely infiltrating carcinoma (n = 3), a prominent ventral/dorsal split (n = 2), and a recent episode (within the previous 4 weeks) of acute pancreatitis (n = 1). Five patients with a negative initial EUS underwent a follow-up EUS after 2-3 months, with a pancreatic mass being found in all cases. Three patients had a diffusely infiltrating pancreatic adenocarcinoma. CONCLUSIONS: EUS is not a foolproof method of detecting a pancreatic neoplasm. Possible associated factors that may increase the likelihood of a false-negative EUS examination include chronic pancreatitis, a diffusely infiltrating carcinoma, a prominent ventral/dorsal split and a recent episode (< 4 weeks) of acute pancreatitis. If there is a high clinical suspicion of pancreatic neoplasm, if EUS and other imaging methods are negative, and if the patient does not undergo surgery, this study suggests that a repeat EUS after 2-3 months may be useful for detecting an occult pancreatic neoplasm.

Acute Disease↗
PubMed2003

Demographic and phenotypic features of 70 families segregating Barrett's oesophagus and oesophageal adenocarcinoma.

BACKGROUND: Based on reported familial patterns, inheritance of a predisposition of developing Barrett's oesesophagus (BO) and oesophageal adenocarcinoma (OAC) likely follows an autosomal dominant model of most inherited cancer syndromes. oesophagus (BO) and oesophageal adenocarcinoma (OAC) likely follows an autosomal dominant model of most inherited cancer syndromes. AIMS: We analysed the phenotypic features of 70 familial BO/OAC families accrued for the purpose of initiating a linkage study to search for genes that contribute to susceptibility for BO/OAC. METHODS: Families with young or familial BO/OAC were recruited from participating institutions and self-referral from advertisement. RESULTS: A total of 70 families (173 affected and 784 unaffected individuals) were recruited into this study. Mean ages of diagnosis of BO and OAC among males were 50.6 and 57.4 years, respectively; among females, 52.1 and 63.5 years, respectively. The standardised incidence ratio (SIR) of cancers other than OAC or oesophagogastric junctional adenocarcinoma (OGJAC), among probands was 0.71. Seventy one percent of the pedigrees have "typical" structures with less than three affected individuals. Power calculations under realistic model assumptions suggest that if genetic heterogeneity is absent or limited, then DNA collection from members of these pedigrees could enable the identification of a novel candidate susceptibility gene for BO/OAC in a genome scan. CONCLUSIONS: This is the largest series of families with BO/OAC yet reported, features of which are consistent with inherited germline predisposition. Further, the SIR of cancers other than OAC/OGJAC was 0.71 among 70 probands, indicating these individuals were not more likely to develop non-OAC cancers.

Adenocarcinoma↗
PubMed2002

Endoscopic ultrasonography.

Over the past two decades, endoscopic ultrasonography (EUS) has undergone a transition from being a novel imaging technique to a clinical diagnostic test that is necessary for the optimal management of gastrointestinal diseases. EUS has established itself as an important diagnostic modality, mainly for the detection and staging of gastrointestinal cancers. As EUS has become more widespread, research has gradually shifted towards studies that explore the effect of EUS on patient management and outcome. These outcome studies have examined the primary clinical applications of EUS, such as esophageal, gastric, pancreatic, and colorectal cancer staging, as well as the role of EUS in the diagnosis of inflammatory pancreatic diseases. Widespread use of EUS has recently led to studies that examine complications associated with the performance of the procedure. Endosonographers have continued efforts to define a clinical role for EUS in other gastrointestinal diseases, such as portal hypertension. EUS-guided fine-needle aspiration (FNA) is continuing to develop into a powerful diagnostic tool for the management of lung cancer and other mediastinal diseases. New applications for EUS-FNA are also emerging. Finally, investigators are continuing to explore the remaining frontier of EUS-guided therapy.

Biopsy, Needle↗
PubMed2002

Familial aggregation of Barrett's oesophagus, oesophageal adenocarcinoma, and oesophagogastric junctional adenocarcinoma in Caucasian adults.

BACKGROUND: Although familial clusters of Barrett's oesophagus and oesophageal adenocarcinoma have been reported, a familial predisposition to these diseases has not been systematically investigated. AIMS: To determine whether Barrett's oesophagus and oesophageal (or oesophagogastric junctional) adenocarcinoma aggregate in families. PATIENTS AND METHODS: A structured questionnaire eliciting details on reflux symptoms, exposure history, and family history was given to Caucasian case (n=58) subjects with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma, and to Caucasian control (n=106) subjects with symptomatic gastro-oesophageal reflux disease without Barrett's oesophagus. Reported diagnoses of family members were confirmed by review of medical records. RESULTS: The presence of a positive family history (that is, first or second degree relative with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma) was significantly higher among case subjects compared with controls (24% v 5%; p<0.005). Case subjects were more likely to be older (p<0.001) and male (74% v 43% male; p<0.0005) compared with control subjects. In a multivariate logistic regression analysis, family history was independently associated with the presence of Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma (odds ratio 12.23, 95% confidence interval 3.34-44.76) after adjusting for age, sex, and the presence of obesity 10 or more years prior to study enrollment. CONCLUSIONS: Individuals with Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma are more likely to have a positive family history of Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma than individuals without Barrett's oesophagus, oesophageal adenocarcinoma, or oesophagogastric junctional adenocarcinoma. A positive family history should be considered when making decisions about screening endoscopy in patients with symptoms of gastro-oesophageal reflux.

Adenocarcinoma↗
PubMed2001

The reliability of EUS for the diagnosis of chronic pancreatitis: interobserver agreement among experienced endosonographers.

BACKGROUND: Endoscopic ultrasound (EUS) is a minimally invasive, low risk method of diagnosis for chronic pancreatitis (CP). The degree to which endosonographers agree on the features and diagnosis of CP is unknown. For EUS to be considered an accurate test for CP, there must be good interobserver agreement. METHODS: Forty-five pancreatic EUS examinations were videotaped by 3 experienced endosonographers. Examinations from 33 patients with suspected CP based on typical symptoms, as well as 12 control patients without suspected CP, were included. Eleven experienced endosonographers ("experts") who were blinded to clinical information independently evaluated all videotaped examinations for the presence of CP and the following 9 validated features of CP: echogenic foci, strands, lobularity, cysts, stones, duct dilatation, duct irregularity, hyperechoic duct margins, and visible side branches. The experts also ranked (most to least) which features they believed to be the most indicative of CP. Interobserver agreement was expressed as the kappa (kappa) statistic. RESULTS: There was moderately good overall agreement for the final diagnosis of CP (kappa = 0.45). Agreement was good for individual features of duct dilatation (kappa = 0.6) and lobularity (kappa = 0.51) but poor for the other 7 features (kappa < 0.4). The expert panel had consensus or near consensus agreement (greater than 90%) on 206 of 450 (46%) individual EUS features including 22 of 45 diagnoses of CP. Agreement on the final diagnosis of CP was moderately good for those trained in third tier fellowships (kappa = 0.42 +/- 0.03) and those with more than 1100 lifetime pancreatic EUS examinations (kappa = 0.46 +/- 0.05). The presence of stones was regarded as the most predictive feature of CP by all endosonographers, followed by visible side branches, cysts, lobularity, irregular main pancreatic duct, hyperechoic foci, hyperechoic strands, main pancreatic duct dilatation, and main duct hyperechoic margins. The most common diagnostic criterion for the diagnosis of CP was the total number of features (median 4 or greater, range 3 or greater to 5 or greater). CONCLUSIONS: EUS is a reliable method for the diagnosis of chronic pancreatitis with good interobserver agreement among experienced endosonographers. Agreement on the EUS diagnosis of chronic pancreatitis is comparable to other commonly used endoscopic procedures such as bleeding ulcer stigmata and computed tomography of the brain for stroke localization and better than the physical diagnosis of heart sounds.

Chronic Disease↗
PubMed2001

Methylene blue staining of dysplastic and nondysplastic Barrett's esophagus: an in vivo and ex vivo study.

BACKGROUND AND STUDY AIMS: Methylene blue selectively stains specialized columnar epithelium in Barrett's esophagus with high accuracy. We prospectively evaluated the methylene blue staining properties of dysplastic and nondysplastic Barrett's esophagus and the association of these properties with the risk for dysplasia and cancer. PATIENTS AND METHODS: In a ex vivo study, we mapped, photographed, and sampled esophagectomy specimens with high grade dysplasia and/or early adenocarcinoma before and after methylene blue staining. In a concurrent in vivo study, we performed methylene blue staining and characterized methylene blue stain characteristics. Pathologists estimated the proportion of specialized columnar epithelium in each specimen and graded dysplasia. RESULTS: We examined 551 biopsies from 47 patients with biopsy-proven Barrett's esophagus and 48 sections from five surgical specimens with Barrett's esophagus and dysplasia and early adenocarcinoma. The accuracy of ex vivo and in vivo methylene blue staining for specialized columnar epithelium was 87% and 90%, respectively. It was influenced by the length of Barrett's esophagus, biopsy location, and the presence of esophagitis and/or dysplasia. Light to absent staining (p = 0.01) and moderate to marked heterogeneity (p = 0.01) were significantly associated with high grade dysplasia or cancer in the univariate analysis and in a multivariate model that adjusted for the length of Barrett's esophagus and the presence of a lesion. These staining characteristics were present in all patients with severe dysplasia and/or adenocarcinoma. CONCLUSIONS: Highly dysplastic or malignant Barrett's esophagus stains differently with methylene blue. Increased heterogeneity and decreased methylene blue stain intensity are significant independent predictors of high grade dysplasia and/or cancer. These features may help to direct biopsies in patients without a lesion.

Adenocarcinoma↗
PubMed2001

Effectiveness of endoscopy in patients admitted to the intensive care unit with upper GI hemorrhage.

BACKGROUND: Esophagogastroduodenoscopy (EGD) is generally indicated for the management of patients admitted to intensive care units (ICUs) with upper gastrointestinal (GI) hemorrhage but its impact in community practice has not been measured. Thus, the effectiveness of 3 EGD factors, viz., accurate initial diagnosis, performance within 24 hours of admission (early EGD), and appropriate intervention, was examined. METHODS: Records of 214 patients admitted to the ICU of 10 metropolitan hospitals with upper GI hemorrhage were reviewed. Unadjusted and severity-adjusted associations of the 3 EGD factors with length of hospital stay, length of ICU stay, readmission to ICU, recurrent bleeding, surgery, and death were evaluated. RESULTS: Inaccurate diagnosis occurred in 10% of patients at initial EGD and was associated with significant increases in risk of recurrent bleeding (70% vs. 11%, p < 0.001), rate of surgery (20% vs. 4%, p < 0.05), length of hospital stay (median 7.5 vs. 5 days, p < 0.005), length of ICU stay (median 4 vs. 2 days, p < 0.005), and rate of readmission to ICU (20% vs. 0.6%, p < 0.001). These associations persisted after adjusting for severity of illness. Early EGD performed in 82% of patients was associated with significant severity-adjusted reductions in hospital (-33%: 95% CI [-45%, -18%]) and ICU (-20%: 95% CI [-24%, -3%]) stay. Appropriate intervention at initial EGD, performed in 84% of patients, was associated with reductions in severity-adjusted length of ICU stay (-18%: 95% CI [-32%, 0%]) and rate of recurrent bleeding (odds ratio = 0.37, 95% CI [0.13, 1.06]). CONCLUSIONS: Early, accurate EGD with appropriate therapeutic intervention is effective as practiced in the community and is associated with improved outcomes for patients with upper GI hemorrhage admitted to the ICU. Inaccurate diagnosis at initial EGD is uncommon but has a significant adverse association with all outcome measures.

Endoscopy, Digestive System↗
PubMed2001

Prospective evaluation of balloon-sheathed catheter US system.

BACKGROUND: Catheter US probes must rely on luminal water to create images because they do not incorporate a water-filled balloon such as that used with a designated echoendoscope. The purpose of this study is to determine the effectiveness and safety of a balloon sheath for the US catheter system. METHODS: Catheter EUS was performed on 50 patients by using a 2.3 mm 12 MHz or 20 MHz catheter probe. Catheter EUS was used in 47 cases, and a newly developed water-filled balloon sheath was used in 41 cases. Both devices were used in 39 cases. Procedure time, depth of ultrasound penetration, and a subjective assessment of image quality and ease of use were recorded, along with TMN stage as applicable. Catheter EUS findings were confirmed with a standard radial scanning echoendoscopy (S-EUS) in 18 cases. RESULTS: Catheter probe EUS (C-EUS) and catheter probe plus balloon (CB-EUS) imaging was obtained of 25 esophageal, 8 gastric, 4 rectal, 1 biliary, and 1 duodenal lesion. Time required for the ultrasound portion of the examination was identical with C-EUS and CB-EUS. Depth of penetration increased with CB-EUS with both the 12 MHz and 20 MHz probes (p < 0.05). Subjective assessment of image clarity improved when CB-EUS was used in the esophagus. C-EUS failed to identify 2 esophageal cancers and 2 sets of paraesophageal lymph nodes, and understaged 1 esophageal cancer. The remaining 14 cancers were staged identically by both modalities. The catheter probes with and without the balloon sheath were easy to use, even in markedly narrow esophageal strictures. CB-EUS did not significantly improve resolution in the stomach or rectum. S-EUS confirmed findings of CB-EUS in all 18 cases in which both instruments were used. There were no procedure-related complications. CONCLUSIONS: For esophageal lesions, CB-EUS improves images compared with C-EUS, and enhances depth of penetration without prolonging or encumbering the examination. CB-EUS offers no advantage over C-EUS in organs other than the esophagus. S-EUS, when possible, remains the preferred imaging modality for esophageal cancers because of the ability to image the celiac axis and other deep structures.

Catheterization↗
PubMed2001

Cervical esophageal perforation during EUS: a national survey.

BACKGROUND: EUS is considered to be as safe a procedure as EGD. However, the longer, rigid tip of the echoendoscopes raises concern about cervical esophageal perforation during intubation. Our aim was to determine the rate of this complication. METHODS: Members of the American Endosonography Club were surveyed by questionnaire to determine the number of EUS examinations performed and the number of cervical esophageal perforations encountered up to June 1999. Each questionnaire was coded to avoid duplicate reporting. RESULTS: Questionnaires were mailed to 203 members; 86 (42.4%) responded. Cervical esophageal perforation occurred in 16 of 43,852 reported upper EUS procedures at a frequency of 0.03%. Fifteen (94%) patients were elderly. A history of difficult intubation with prior endoscopic procedures was present in 7 (44%) patients. Three patients had large cervical osteophytes. In 9 (56%) patients, the procedure was done by an endosonographer with less than 1 year of experience. Two patients required surgery. One patient died as a result of the perforation and the other 13 (81%) patients were managed successfully with conservative treatment. CONCLUSIONS: The incidence of cervical perforation during upper EUS may be higher than during EGD. Advanced patient age, difficult intubation during prior upper endoscopy, operator inexperience, and the presence of large cervical osteophytes may contribute to cervical perforation during upper EUS examination.

Aged↗
PubMed2001

Wire-guided intraductal US: an adjunct to ERCP in the management of bile duct stones.

BACKGROUND: Endoscopic retrograde cholangiography (ERC) may misdiagnose bile duct stones if air bubbles are introduced during contrast injection, and it may also fail to diagnose stones in the presence of bile duct dilation. METHODS: Our aim was to determine whether intraductal US (IDUS) improves the accuracy of cholangiography and whether it is a useful adjunct in the management of bile duct stones. IDUS with a wire-guided US probe was performed after initial ERC in patients in whom bile duct stones were suspected. The diagnostic accuracy of ERC alone was compared with that of ERC plus IDUS. RESULTS: ERC with IDUS was performed in 62 patients who were suspected to have bile duct stones. Both IDUS and ERC were performed by the same endoscopist, and ERC was performed with a C-arm fluoroscope. The presence of bile duct stones and/or sludge were confirmed after sphincterotomy and extraction in 34 patients. Overall, the accuracy of ERC combined with IDUS in the diagnosis of bile duct stone and/or sludge was higher than that of ERC alone (97% vs. 87%, p < 0.05). With dilated bile ducts, the diagnostic accuracy of ERC combined with IDUS was also higher than that of ERC alone (95.5% vs. 72.7%, p < 0.05). Additional diagnostic information provided by IDUS included identification of cystic duct stones in 5 patients, characterization of bile duct strictures in 2 patients, and choledochal varices in 1 patient. Performance of wire-guided IDUS required 5% of the total procedure time. CONCLUSIONS: IDUS improves diagnostic accuracy of ERC and is a useful adjunct to ERC when bile duct stones are suspected.

Aged↗
PubMed2001

High-resolution endoscopic imaging of the GI tract: a comparative study of optical coherence tomography versus high-frequency catheter probe EUS.

BACKGROUND: Both optical coherence tomography (OCT) and catheter probe EUS (CPEUS) are candidates for high-resolution imaging of the GI wall, but their potential roles in this clinical context have not been investigated. METHODS: OCT and CPEUS were used to image normal-appearing portions of the GI tract at the same sites. CPEUS was performed with a 20-MHz or a new 30-MHz catheter probe. RESULTS: Forty-four histologically confirmed normal sites in 27 patients were evaluated. With OCT, mucosa and muscularis mucosa were clearly seen at all sites. Except for stomach, OCT demonstrated the submucosa in all sites. OCT penetration ranged from 0.7 to 0.9 mm. Microscopic structures such as esophageal glands, intestinal villi, colonic crypts, and blood vessels were easily identified. CPEUS penetration ranged from 10 mm to 20 mm, and 5 to 7 distinct layers were discernible. However, both mucosa and submucosa were seen as thin layers without microscopic detail. CONCLUSION: OCT resolution is superior to high-frequency CPEUS, but depth of penetration is limited to mucosa and submucosa. OCT images the major structural components of the mucosa and submucosa whereas CPEUS does not. Potentially, OCT and high-frequency CPEUS may be complementary for clinical imaging.

Endoscopy, Gastrointestinal↗
PubMed2001

Evaluation of a rapid urine amylase test using post-ERCP hyperamylasemia as a model.

OBJECTIVE: The initial diagnosis of acute pancreatitis is often based on clinical criteria together with elevations of serum amylase and lipase. A reliable bedside urine test could facilitate the early diagnosis of pancreatitis. We evaluated a rapid urine amylase test (Rapignost) by using post-ERCP hyperamylasemia as a human model of acute development of hyperamylasemia suggestive of pancreatitis. METHODS: Seventy-five patients undergoing ERCP were prospectively evaluated. Patients with renal insufficiency, hyperlipidemia, or hyperglycemia were excluded. Before ERCP, patients had serum amylase and lipase measured, and urine amylase tested with the Rapignost test strip. At 4 and 16-24 h post-ERCP, a serum and urine (test strip) amylase were measured again; the adequacy of urine collection was verified by measuring a 2-h creatinine clearance. Patients were clinically assessed for the development of clinical pancreatitis. The concordance of the strip result with post-ERCP hyperamylasemia was assessed. RESULTS: The sensitivity of the test strip for the detection of hyperamylasemia was greatest at 16-24 h post-ERCP (78%). Specificity was uniformally high (100% specificity at 16-24 h post-procedure). The test strip was positive in all cases of clinical pancreatitis. Of three cases of clinically evident ERCP-induced pancreatitis, only one was urine test strip positive by 4 h post-procedure. CONCLUSIONS: Using post-ERCP hyperamylasemia as a model, the Rapignost rapid urine amylase test strip was only marginally sensitive but highly specific for hyperamylasemia. The urine test strip was positive in all cases of clinical pancreatitis and may be a useful bedside test for the diagnosis of acute pancreatitis.

Adolescent↗