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Amitabh Chak

Publications and source records attributed to Amitabh Chak.

At least 55 records · Page 3Linked to original sources
PubMed2004

An international survey of the clinical practice of EUS.

BACKGROUND: No comparative information exists regarding clinical variations in EUS practice patterns among American and international endosonographers. METHODS: Eligible attendees of the XIIIth International Symposium on EUS, October 4-6 2002, New York, New York, were asked to complete a 2-page survey questionnaire on clinical practice of EUS. RESULTS: A total of 191 of 391 eligible attendees (48.9%) participated in the survey (110 from the United States, 81 from 30 different countries). The mean age of participants was 40.5 (10.6) years, and 171 (89.5%) were men. A total of 102 endosonographers (53.4%) were in academic practice. The majority (150, 78.5%) also performed ERCP. Seventy-eight (40.8%) had performed EUS for more than 5 years and 21 (11%) for less than 1 year. Only 36 (18.8%) had more than 6 months of dedicated hands-on EUS training, and more than a third of the respondents learned to perform EUS by observing others or they were self-taught. Compared with respondents from the United States, relatively fewer international respondents were performing open-access EUS, pancreatobiliary EUS procedures, and interventions such as EUS-guided FNA and celiac plexus neuralysis. CONCLUSIONS: This survey provides insight into the status of EUS as practiced in the United States and internationally. Although it appears that over the last decade EUS has become disseminated fairly uniformly on a global basis, a lack of consistent training standards and also inadequate opportunities for EUS training remain important areas of concern.

Adult↗
PubMed2004

Success and shortcomings of a clinical care pathway in the management of acute nonvariceal upper gastrointestinal bleeding.

OBJECTIVES: Acute nonvariceal upper gastrointestinal (GI) bleeding is the most common medical emergency encountered by gastroenterologists resulting in high patient morbidity and cost. We sought to establish if a GI bleeding clinical care pathway could improve the quality and cost effectiveness of inpatient medical care. METHODS: A disease management program for acute upper GI bleeding was established. Length of stay, time to endoscopy, utilization of potentially unnecessary radiological tests, acid suppression, and cost of care were compared between patients pre- and postinitiation of GI bleeding pathway guidelines. RESULTS: The instituted GI bleeding management program significantly reduced the use of intravenous H2-blockade from 65.3% to 47.7% (p = 0.002). The use of radiological tests, time to endoscopy, and length of hospital of stay were unchanged. There was a trend toward a reduction in total cost and variable direct cost per patient admitted with acute upper GI bleeding, from $5,381 to $4,627 and from $2,269 to $1,952, respectively. CONCLUSION: A clinical care pathway may affect the management of acute upper GI bleeding and reduce costs. However, there are significant limitations and barriers to the overall effectiveness of such a pathway in actual clinical practice.

Acute Disease↗
PubMed2004

Identification of Barrett's esophagus in relatives by endoscopic screening.

AIM: Familial aggregation of Barrett's esophagus and its associated cancers has been termed familial Barrett's esophagus (FBE). The aim of the study was to determine whether endoscopic screening would identify Barrett's esophagus (BE) in relatives of probands with BE or esophageal adenocarcinoma (EAC). METHODS: All living first-degree relatives of patients with long segment BE or EAC presenting to the endoscopy suite of two academic hospitals were sent validated questionnaires inquiring about gastroesophageal reflux symptoms and prior endoscopic evaluation. First-degree relatives of affected probands or affected relatives who reported no prior upper endoscopy were offered screening unsedated esophagoscopy. Relatives with chronic gastroesophageal reflux symptoms were also offered an alternative of conventional sedated upper endoscopy. The yield of screening endoscopy was measured. Screening endoscopy findings were then compared between family members of known FBE patients and those with "isolated" disease. RESULTS: One hundred and ninety-eight relatives from 69 families, 23 known FBE probands and 46 probands with apparently "isolated" disease, were enrolled. Forty relatives (29 FBE relatives and 11 relatives of probands with "isolated" disease) reported prior upper endoscopy. Screening upper endoscopies performed on 62 (25 FBE and 37 "isolated" disease relatives) of the remaining 158 relatives identified Barrett's epithelium in 13 (21%). Compared to probands with apparently "isolated" disease, Barrett's epithelium (EAC, BE, or SSBE) was identified significantly more often in siblings and offspring of FBE probands, p</= 0.05. Endoscopic screening of relatives of FBE probands identified a multigeneration multiplex FBE pedigree consistent with an autosomally dominant inherited trait. Endoscopic screening of relatives of probands with reported "isolated" diseased did not identify any new FBE pedigrees. CONCLUSIONS: Endoscopy identified EAC, long-segment BE, and short-segment BE in a substantial proportion of first-degree relatives of affected members of FBE families. A familial susceptibility to develop Barrett's epithelium appears to be present in a subset of patients with BE and EAC.

Adenocarcinoma↗
PubMed2003

Prediction of outcome in acute lower-gastrointestinal haemorrhage based on an artificial neural network: internal and external validation of a predictive model.

BACKGROUND: Models based on artificial neural networks (ANN) are useful in predicting outcome of various disorders. There is currently no useful predictive model for risk assessment in acute lower-gastrointestinal haemorrhage. We investigated whether ANN models using information available during triage could predict clinical outcome in patients with this disorder. METHODS: ANN and multiple-logistic-regression (MLR) models were constructed from non-endoscopic data of patients admitted with acute lower-gastrointestinal haemorrhage. The performance of ANN in classifying patients into high-risk and low-risk groups was compared with that of another validated scoring system (BLEED), with the outcome variables recurrent bleeding, death, and therapeutic interventions for control of haemorrhage. The ANN models were trained with data from patients admitted to the primary institution during the first 12 months (n=120) and then internally validated with data from patients admitted to the same institution during the next 6 months (n=70). The ANN models were then externally validated and direct comparison made with MLR in patients admitted to an independent institution in another US state (n=142). FINDINGS: Clinical features were similar for training and validation groups. The predictive accuracy of ANN was significantly better than that of BLEED (predictive accuracy in internal validation group for death 87% vs 21%; for recurrent bleeding 89% vs 41%; and for intervention 96% vs 46%) and similar to MLR. During external validation, ANN performed well in predicting death (97%), recurrent bleeding (93%), and need for intervention (94%), and it was superior to MLR (70%, 73%, and 70%, respectively). INTERPRETATION: ANN can accurately predict the outcome for patients presenting with acute lower-gastrointestinal haemorrhage and may be generally useful for the risk stratification of these patients.

Acute Disease↗
PubMed2003

Long-term follow-up of patients with clinically indeterminate suspicion of pancreatic cancer and normal EUS.

BACKGROUND: EUS often is performed because of a clinical suspicion of pancreatic cancer when the results of other noninvasive diagnostic tests are indeterminate. The aim of this study was to determine the true negative predictive value of a normal EUS in a cohort of patients with an indeterminate suspicion of pancreatic cancer by obtaining long-term follow-up information. METHODS: Patients referred for EUS of the pancreas for the following indications were identified: elevated carbohydrate-associated antigen (CA 19-9) without other definitive evidence of pancreatic cancer, subtle abnormalities on CT of the pancreas, and unexplained abdominal pain and/or weight loss. Endoscopy procedure reports, as well as inpatient and outpatient records were obtained. In addition, referring physicians, as well as patients, were contacted to acquire adequate follow-up information. RESULTS: A total of 80 patients were included in the study. Follow-up of at least 6 months was obtained for 76 (95%) patients (mean follow-up 23.9 months). No patient with a normal EUS of the pancreas developed pancreatic cancer or required pancreatic surgery during the follow-up period. One patient in whom a diagnosis of chronic pancreatitis was made by EUS subsequently was found to have pancreatic cancer at surgery. CONCLUSIONS: A normal EUS of the pancreas in the setting of subtle radiologic findings, serologic abnormalities, and/or nonspecific symptoms definitively rules out the presence of pancreatic cancer.

CA-19-9 Antigen↗
PubMed2003

Evaluation of a new curved linear array echoendoscopy system for EUS.

BACKGROUND: EUS-FNA can be used to accurately diagnose and stage GI and pulmonary neoplasms. This study evaluated the performance characteristics of a new compact linear EUS system during EUS-FNA. METHODS: A total of 37 patients enrolled in this prospective pilot study underwent clinically indicated EUS-FNA and/or celiac plexus neurolysis with the compact EUS system. RESULTS: The mean time to perform a radial and linear array EUS with FNA and/or celiac plexus neurolysis was 24 minutes shorter with the compact EUS system compared with that for an historical control procedure in which a conventional linear EUS unit was used (p = 0.0007). The EUS images and visualization of the needle during EUS-FNA were rated good to excellent in greater than 95% of the patients. With respect to ease of esophageal intubation, duodenal intubation, and general maneuverability, the performance of the new linear echoendoscope, compared with a radial scanning videoechoendoscope, was the same or better in, respectively, 85%, 87%, and 100% of procedures. The video image quality of the new linear array echoendoscope was superior to that of the radial scanning videoechoendoscope in all patients. No complications were encountered. CONCLUSIONS: EUS-FNA and celiac plexus neurolysis can be performed safely with the new compact EUS system. The efficiency of this procedure is enhanced compared with historical experience with other instruments. Although image quality is sufficient for EUS-FNA and celiac plexus neurolysis, the compact unit cannot be used as a "stand-alone" system for routine diagnostic EUS, and its use must be complemented by standard radial imaging.

Biopsy, Needle↗
PubMed2003

Innovative methods of biliary tract diagnosis: intraductal ultrasound and tissue acquisition.

Tissue can be acquired from the bile and pancreatic duct with either brush cytology or biopsy forceps, often without the need for sphincterotomy. Although the diagnosis of malignancy with these sampling techniques is often specific, the sensitivity is limited, and a wide range of diagnostic accuracies has been reported. A combination of biopsy and brush cytology along with some newer techniques in the development stage may increase the sensitivity. Intraductal ultrasound is a newer technique offers the endoscopist the ability to image the bile and pancreatic duct wall, adjacent organs, and vascular structures with a high degree of detail. This visualization can be accomplished during the course of an ERCP or percutaneously under fluoroscopic guidance. Indications for the procedure include detection of choledocholithiasis, differentiation of benign and malignant ductal strictures, pancreaticobiliary tumor staging, and detection of various pancreatic tumors. Continued research into the design of the probes, which could improve durability and extend the depth of penetration, may promote more widespread use of this novel technology.

Bile Ducts↗
PubMed2003

Prospective evaluation of 4-mm diameter endoscopes for esophagoscopy in sedated and unsedated patients.

BACKGROUND: Unsedated esophagoscopy with small-diameter endoscopes is generally well tolerated but of limited sensitivity for the diagnosis of esophageal mucosal disease. This study evaluated the sensitivity of esophagoscopy performed with new 4-mm diameter prototype battery-powered and video endoscopes. Patient tolerance for an unsedated examination with the 4-mm endoscopes was assessed and the performance characteristics of the battery-powered and video 4-mm endoscopes were compared. METHODS: Patients referred for EGD were recruited to undergo an additional examination with a 4-mm endoscope. A prototype 60-cm long, 4-mm diameter battery-powered fiberoptic esophagoscope was used in the first 24 patients and a prototype 60-cm long, 4-mm diameter video esophagoscope in the next 27 patients. Examiners who were unaware of patient history and procedure indications recorded esophageal findings, ease of intubation, optical quality (5-point visual scale), and time for examination of the esophagus and then recorded esophageal findings after the standard EGD. RESULTS: The sensitivity, specificity, and accuracy for identification of Barrett's esophagus was 100%; overall sensitivity, accuracy, and specificity for detecting esophageal lesions were, respectively, 91%, 98%, and 99%. Patient tolerance (assessed by symptom scores for choking, pain, and discomfort) and acceptability of unsedated esophagoscopy with the 4-mm diameter instruments were significantly better than in a historical group of patients examined with a 3-mm diameter endoscope. The optical quality of video endoscope was rated as superior to that of battery-powered endoscope, and esophageal examination was performed significantly quicker with the video versus the battery-powered endoscope (68 vs. 137 seconds; p = 0.001). CONCLUSIONS: Unsedated esophagoscopy with 4-mm diameter endoscopes may be an alternative to EGD for screening for Barrett's esophagus. Given the current state of endoscopic technology, a minimum diameter of 4 mm is required for satisfactory esophageal imaging.

Barrett Esophagus↗
PubMed2003

Clinical utility of intraductal US for evaluation of choledocholithiasis.

BACKGROUND: Intraductal US can improve the diagnostic accuracy of cholangiography performed under C-arm fluoroscopy in patients with suspected choledocholithiasis. This study aimed to determine the clinical utility of intraductal US for patient management. METHODS: Patients with suspected choledocholithiasis undergoing ERCP with a C-arm fluoroscope at two tertiary academic medical centers were enrolled. After initial cholangiography, findings and decisions concerning the need for further interventions were recorded. Intraductal US (20 MHz) was then selectively performed in patients with equivocal cholangiography or those without cholangiographic evidence of bile duct stones. Intraductal US was also performed after endoscopic sphincterotomy and stone extraction to confirm bile duct clearance. RESULTS: Fifty-two patients (28 men, 24 women) were enrolled and intraductal US was selectively performed in 35 (64%). Of the 21 patients with normal cholangiography, 8 (38%) had stones or sludge by intraductal US. Endoscopic sphincterotomy was performed as a direct result of intraductal US in these 8 and the findings were confirmed in 7. In the 14 patients in whom cholangiography demonstrated small (<5 mm) or round filling defects, intraductal US concurred in 9 and found air bubble/no stone in 5. Sphincterotomy was avoided in these 5 patients. Overall, intraductal US led to a change in clinical management in 13 of 35 patients (37%) in whom it was performed. CONCLUSIONS: Selective use of intraductal US affects the clinical management of a large proportion of patients who undergo C-arm fluoroscopy-guided ERCP for suspected bile duct stones.

Adult↗
PubMed2003

Unsedated EGD.

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Procedural Sedation↗
PubMed2003

Criteria for the diagnosis of dysplasia by endoscopic optical coherence tomography.

BACKGROUND: Endoscopic optical coherence tomography provides images of the GI mucosa and submucosa in microscopic detail. It is unknown whether endoscopic optical coherence tomography can reliably detect dysplasia. Colon polyps were used as a model to determine whether dysplasia in GI tissue has characteristic optical coherence tomography imaging features. METHODS: Endoscopic optical coherence tomography images of colon polyps and normal colon tissue were obtained at colonoscopy. In real time, endoscopists compared tissue organization and light scattering for polyps and normal mucosa with endoscopic optical coherence tomography. Imaged polyps were removed and evaluated histopathologically. Organization and light scattering, as assessed by endoscopic optical coherence tomography at colonoscopy, were compared for adenomas versus hyperplastic polyps. A computer program also quantified and compared the degree of light scattering for hyperplastic polyps and adenomas. RESULTS: A total of 44 polyps were imaged in 24 patients (30 adenomas, 14 hyperplastic polyps). Endoscopic optical coherence tomography images of adenomas had significantly less structure (p = 0.0005) and scattered light to a lesser degree than hyperplastic polyps (p = 0.0007). Hyperplastic polyps were significantly closer in organization (p = 0.0003) and light scattering (p = 0.0006) to normal mucosa as compared with adenomas. By digital image analysis, the light-scattering property of hyperplastic polyps was closer to normal mucosa compared with adenomas (14.86 vs. 45.81; p = 0.0001). CONCLUSIONS: Real-time endoscopic optical coherence tomography imaging differentiated adenomas, hyperplastic polyps, and normal colon tissue. By using the colon adenoma as a model, the endoscopic optical coherence tomography characteristics of dysplasia are loss of tissue organization and reduced light scattering.

Adenoma↗
PubMed2003

Effectiveness of open-access endoscopy in routine primary-care practice.

BACKGROUND: Direct referral of patients for endoscopic procedures without prior consultation (open-access endoscopy) has become commonplace. However, the effect of open-access endoscopy on the care of patients in routine clinical practice has not been studied. METHODS: The impact of open-access endoscopy was examined in 168 consecutive patients referred from 8 primary-care practices to our tertiary hospital-based endoscopy center. The effectiveness of open-access endoscopy was assessed by review of office medical records at the primary-care practice sites for a minimum follow-up period of 6 months. Outcome measures evaluated included postprocedure communication between primary-care physician and patient, primary-care physician adherence to postprocedure recommendations, and the need for subsequent diagnostic evaluation and/or consultation. RESULTS: The mean age of the 168 patients was 60 years; 56 (33%) underwent EGD and 112 (67%) had colonoscopy; 65% were from hospital-based practices and 35% from community practices. The indication(s) for 77% of the procedures met American Society for Gastrointestinal Endoscopy guidelines for the appropriate use of endoscopy. An office follow-up was noted for 82% of patients after the open-access procedure. Discussion of results was documented in 61% of the patient charts. Compliance with diagnostic and therapeutic recommendations was documented, respectively, in 75% and 90% of patient charts. A follow-up GI consultation was requested for only 7% of the patients. CONCLUSION: Open-access endoscopy in the primary-care setting is effective to the extent that subsequent GI consultations are rare and the level of compliance with endoscopist recommendations is high. However, documentation of communication of the results of endoscopy with the patient can be improved.

Aged↗
PubMed2003

A time for change.

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Endoscopy, Gastrointestinal↗
PubMed2003

Role of endoscopic ultrasonography in the staging of esophageal cancer: a review.

PURPOSE OF REVIEW: This review summarizes the important studies, published since April 2002, on the role of endoscopic ultrasonography for staging of esophageal cancer. RECENT FINDINGS: The loco-regional staging accuracy for esophageal cancer by endoscopic ultrasonography is superior to other currently available imaging modalities such as helical computed tomography. Endoscopic ultrasonographic staging accuracy is further enhanced by the ability to obtain guided fine needle aspiration specimens for cytology from any suspicious celiac lymph nodes. In addition to the initial staging of esophageal cancer, endoscopic ultrasonography-based measurement of reduction of tumor cross-sectional area appears to be a reliable predictor of pathologic response to initial neoadjuvant therapy. Recently published studies on the outcomes of endoscopic ultrasonography support its utility in the staging of esophageal cancer, particularly in guiding different treatment options for different stages of loco-regional involvement. SUMMARY: Overall, endoscopic ultrasonography for staging of patients with esophageal cancer seems to be a cost-effective intervention.

Journal Article↗
PubMed2002

Association of prediagnosis endoscopy with stage and survival in adenocarcinoma of the esophagus and gastric cardia.

BACKGROUND: Barrett esophagus, a consequence of chronic gastroesophageal reflux disease, is a premalignant condition for adenocarcinoma of the esophagus and, possibly, the gastric cardia. However, the actual use and clinical impact of upper gastrointestinal endoscopy in screening and surveillance for Barrett esophagus are unknown. METHODS: A cohort included 1633 patients with adenocarcinoma (777 esophagus, 856 cardia) who were 70 years or older. They were diagnosed between 1993 and 1996 and were identified from the Surveillance, Epidemiology and End Results program registry. All claims for upper endoscopy and a diagnosis of Barrett esophagus from 1991 through 1 year before diagnosis were identified from linked Medicare files. RESULTS: One or more upper endoscopies before diagnosis were performed in 9.7% of patients (13.0% esophagus, 6.8% cardia) and a diagnosis of Barrett esophagus was present in only 3.7% of patients. A shift toward earlier stage at diagnosis was observed in patients with previous endoscopy or Barrett diagnosis. For example, 62% of patients with esophageal and 49% of patients with cardia tumors who underwent previous endoscopy presented with in situ or local stage carcinoma, compared with 35% and 27% of other patients, respectively. Receipt of endoscopy was also associated with a reduced risk of death for esophageal adenocarcinoma (relative hazard 0.73, 95% confidence interval 0.57-0.93; P = 0.01), but not for adenocarcinoma of the cardia. CONCLUSIONS: Receipt of upper endoscopy at least 1 year before diagnosis of adenocarcinoma, which may reflect prediagnosis screening, was associated with an earlier tumor stage and improved survival. These data support the role of endoscopic screening and surveillance for Barrett esophagus and highlight the underdiagnosis of populations at risk.

Adenocarcinoma↗