- Email: [email protected]
W1051 Adherence to Surveillance Interval Guidelines in Barrett's Esophagus (BE): Analysis From a Large Multicenter Cohort Study
AGA Abstracts
polyps was surveillance from history of colorectal cancer (29.3%; OR=0.68; (95% CI, 0.670.69), followed by heme-positive stool (24%; OR= 0.51; (95% CI, 0.50-0.52), followed by iron deficiency anemia (23%; OR= 0.48, (95% CI, 0.47-0.49). Procedures done for screening revealed the least rate of cancer (0.13%; OR= 0.12; (95% CI 0.11-0.14) and Colonoscopies done for the purpose of abdominal pain showed the lowest rate of polyps (16.5%; OR=0.3; (95% CI 0.3-0.32) Native Americans undergoing screening colonoscopy were found to have the highest rate of colon cancer (0.43%) as compared to other ethnicity groups. Conclusions: Colonoscopic findings of colon cancer was highest among patients who presented with iron deficiency anemia, abdominal mass and positive FOBT.Native Americans undergoing screening colonoscopy had the highest rate of colon polyps and cancer.
with 95% confidence intervals (CI). Results: Over 11 months, 231 patients were enrolled (176(76%) ERCP and 55(24%) EUS). SRC included SaO2 <90% (6.9%), SBP <90mmHg (15.1%), premature termination of the procedure (0.9%), and ≥1AMs (12.1%). Bag-mask ventilation was required in 1.2%. There were no cases requiring endotracheal intubation. 152 (65.8%) patients met criteria for OSA+. The frequency of AMs was significantly higher among OSA+ (15.8%) compared to OSA- (5.1%) patients (OR 3.5 [1.2-10.5]). On univariate analysis, other clinical features (ASA class, Mallampati score) and procedure characteristics (prone position, induction or total propofol dose, endoscopy time) were not predictive of AMs. Regression analysis including each component of STOP-BANG revealed the strongest independent predictor of AMs was a history of witnessed apnea while sleeping (OR 5.9 [1.8-19.6]). Conclusion: Among patients undergoing advanced endoscopy, 65.8% of patients were high risk for OSA. Using a bedside screening tool, patients classified as high risk are more likely to require AMs during advanced endoscopy. W1050 Prospective Evaluation of Graft Versus Host Disease (GVHD) in the Gastrointestinal (GI) Tract to Determine the Optimal Biopsy Site for Diagnosis: Looking for a Smoking Gun in a Haystack Ethan D. Miller, Giovanni DePetris, Roberta H. Adams, Michael D. Crowell, Deloris K. Hutt, Mashal J. Batheja, Juan F. Gallegos-Orozco, Nancy J. Han, J. C. Hernandez, Jonathan A. Leighton, Hack J. Kim, Jose F. Leis, James L. Slack, G. A. Decker GVHD is a common complication of allogeneic stem cell transplantation (SCT), and is a significant cause of post-SCT mortality. Signs and symptoms of GI GVHD are non-specific (e.g., nausea, vomiting and diarrhea). It is critical to differentiate GVHD from other causes, since its treatment entails steroid administration and is associated with risks. Endoscopicallyobtained mucosal biopsies are used for histological confirmation when GI GVHD is suspected. The biopsy site with the highest yield is not known, although some reports have favored the rectal mucosa. AIM To compare the diagnostic yield of biopsies obtained from different sites in the GI tract in patients with suspected GVHD. METHODS IRB approval was obtained. SCT recipients at Mayo Clinic Arizona suspected of having GI GVHD were identified. Each patient underwent an esophagogastroduodenoscopy (EGD) and flexible sigmoidoscopy (FS). Mucosal biopsies were collected in a standardized fashion from each of the following sites, regardless of mucosal appearance: gastric antrum, gastric body, duodenum, and rectum. Pathologists reviewed the specimens and diagnosed GVHD based on the presence of apoptosis and/or crypt drop-out that could not be otherwise explained. Immunohistochemistry for cytomegalovirus (CMV) was also performed. RESULTS Twenty-two SCT recipients (median age 58.5, 11 women) underwent EGD and FS per protocol. Symptoms included nausea (77%); vomiting (64%); diarrhea (68%); abdominal pain (50%); and rectal bleeding (4.5%). Endoscopic findings ranged from normal mucosa to focal erythema or erosions. There were no complications. CMV was negative in all specimens. Histological findings suggested GVHD in 19 of 22 patients (86%). The diagnostic yields of EGD and FS biopsies were 68.2% (15/ 22 patients) and 72.7% (16/22 patients), respectively (p=NS). Neither the mucosal appearance nor symptoms predicted histology. In 3 patients (13.6%) the diagnosis was made by EGD alone, and in 4 patients (18.2%) the diagnosis was made by FS alone. The level of agreement between: (1) any EGD and FS biopsy results was 68% (95% CI, 47-84%); (2) gastric antral and rectal biopsy results was 41% (95% CI, 23-61%); (3) gastric body and rectal biopsy results was 36% (95% CI, 20-57%); and (4) duodenal and rectal biopsy results was 68% (95% CI, 23-61%). There were no cases in which gastric biopsies were positive but duodenal biopsies negative. CONCLUSIONS Contrary to previous reports, this study suggests that both EGD and FS may be necessary to reliably identify GI GVHD. For EGD, gastric biopsies do not add to the yield of duodenal biopsies.
W1048 Safety of Nurse Administered Propofol Sedation (NAPS) in ERCP Gregory A. Cote, John M. DeWitt, Evan L. Fogel, Glen A. Lehman, Lee McHenry, James L. Watkins, Stuart Sherman Background: While the safety of registered nurse (RN) administered propofol sedation (NAPS) in standard endoscopy is well established, there are limited data using NAPS for patients undergoing ERCP. Objective: Determine the safety of NAPS in patients undergoing ERCP at a tertiary medical center. Methods: Standard practice in ERCP at our institution is to use combination intravenous (IV) benzodiazepine and opiate (meperidine or fentanyl) with or without low dose droperidol. When a RN trained in NAPS was available, propofol was either used as: 1) “rescue” for patients failing to achieve adequate sedation with standard medications, or 2) with balanced propofol sedation (BPS), defined as propofol with low doses of combination IV benzodiazepine and opiate. Patients undergoing ERCP between May, 2007 and November, 2009 who received propofol in a NAPS protocol were identified in an endoscopy database. Propofol was administered by an ACLS-certified RN who had previously completed a training program in NAPS. The RN, under the supervision of the treating endoscopist, administered IV propofol in incremental doses of 10-40mg, titrating to achieve moderate or deep sedation. Capnography was not used for supplemental monitoring. Sedation-related complications (SRCs) included hypoxemia (pulse oximetry < 90%), decline in systolic blood pressure > 25% from baseline or < 90mmHg, aspiration, bag-mask ventilation, and premature termination of the procedure. Data are reported as medians with interquartile ranges. Results: 71 patients (median age 47 (37-54), 63% females) were identified. ASA class ≥3 was reported in 6 (8%). Indications included biliary obstruction in 28 (39%), suspected sphincter of Oddi dysfunction in 16 (23%), and removal of a pancreatic duct stent in 13 (18%). Endoscopic drainage of a pancreatic pseudocyst was performed in 5 (7%) cases of combined ERCP and EUS. Median endoscopy time was 28 minutes (1939). Sedation medications included a median total propofol dose of 220mg (130-370), midazolam 2mg (2-4) and either meperidine 50mg (50-75) or fentanyl 50mcg (50-75). Droperidol was used in 8 (11%) cases (median dose 6mg (5-7)). SRCs were identified in 3 of 71 (4%), including hypoxemia in 2 and transient hypotension in 1. One case required transient bag-mask ventilation and premature termination of the procedure. There were no cases of aspiration, and neither vasopressors nor endotracheal intubation were required. Conclusion: The frequency of SRCs using NAPS in ERCP is low (4%). In addition to being an effective “rescue” sedative for refractory patients, BPS appears feasible in ERCP. Larger studies are needed to verify these results.
W1051 Adherence to Surveillance Interval Guidelines in Barrett's Esophagus (BE): Analysis From a Large Multicenter Cohort Study Neil Gupta, Amy Wang, Patrick E. Young, Sachin B. Wani, Ajay Bansal, Keng-Yu Chuang, Hemanth Gavini, Vikram Boolchand, Priti Sud, John Kuczynski, Srinivas Gaddam, Vikas Singh, Mandeep Singh, April D. Higbee, Brooks D. Cash, Amit Rastogi, Sharad C. Mathur, David A. Lieberman, Gary W. Falk, Richard E. Sampliner, Prateek Sharma
W1049
Background: Despite the controversies, BE surveillance is commonly practiced in the US. However, data on adherence to surveillance interval guidelines are limited. Aim: To determine adherence rates for surveillance interval guidelines in BE patients managed at veteran and non-veteran tertiary care centers. Methods: A multi-center (5 centers) BE cohort database was analyzed. Diagnosis of BE required histologically confirmed intestinal metaplasia. Patients with no dysplasia (NDBE) or low grade dysplasia (LGD) at index endoscopy were included. Adherence was defined as a repeat endoscopy within 1-3 years of diagnosis for NDBE and 6-12 months for LGD. The following variables were included in the analysis: age, gender, race, BE length, study site, and date of diagnosis. Fisher's exact test and an unpaired t-test were used to compare categorical and continuous variables, respectively. Factors significant on univariate analysis were examined using a stepwise, multivariate logistic regression model to examine predictors for adherence. Results: A total of 2080 BE patients were diagnosed between October, 1990 - October, 2006 [NDBE (1788, 86.0%), LGD (292, 14.0%)]. Of these patients, 1236 (59.4%) underwent repeat surveillance endoscopy within the intervals defined above. Adherence rates were significantly higher in patients with LGD compared to NDBE (67.5% vs. 58.1%, {p = 0.003}), males vs. females (60.7% vs 49.8% {p =0.001}), and veterans vs. non-veterans (69.0% vs. 47.8%, {p<0.001}). Mean BE length was significantly longer in patients who were adherent compared to those not adherent (4.1cm vs. 3.7cm, p=0.0377). No differences in adherence rates were seen based on race, age, or decade of diagnosis. In the multivariate analysis, presence of LGD [OR 1.35 (95% CI 1.01 - 1.81), p=0.039], BE length [OR 1.06 (95% CI 1.03 - 1.10), p<0.001], and veteran status [OR 2.82 (95% CI 2.30 - 3.46), p<0.001) were independent predictors for adherence. Conclusions: Despite published guidelines for BE surveillance, overall adherence rates were low even at centers with expertise in BE. Patients with LGD, longer BE length, and veterans were more likely to undergo surveillance. Future studies should evaluate patient and physician factors affecting adherence to BE surveillance guidelines.
Prevalence of Obstructive Sleep Apnea Among Patients Undergoing Advanced Endoscopic Procedures Using Crna-Administered Propofol for Sedation: Use of a Beside Screening Instrument to Predict Sedation-Related Complications Gregory A. Cote, Christine E. Hovis, Robert M. Hovis, Lawrence Waldbaum, Riad R. Azar, Dayna S. Early, Steven A. Edmundowicz, Daniel Mullady, Sreenivasa S. Jonnalagadda Background: A majority of patients with obstructive sleep apnea (OSA) remain undiagnosed. Among patients undergoing advanced endoscopy (ERCP, EUS), unrecognized OSA is likely to be a predictor of sedation-related complications (SRC), particularly the need for airway modifications (AMs). Objective: Using an OSA screening tool, define the prevalence of OSA in patients undergoing advanced endoscopic procedures and correlate with the frequency of AMs. Methods: Consecutive patients undergoing ERCP and EUS were enrolled. Propofolbased sedation and patient monitoring were performed by a certified registered nurse anesthetist (CRNA) and an anesthesiologist. A previously validated screening tool, STOP-BANG, which includes 4 questions and 4 clinical features (age >50, male sex, BMI >35kg/m2, neck circumference >40cm) was completed prior to the endoscopy to assess OSA risk. Scores ≥3 of 8 have high sensitivity and negative predictive value for moderate to severe OSA. For improved specificity, we defined high risk for OSA as a STOP-BANG of >3 (OSA+). Primary outcomes were to define the frequency of OSA+ patients and compare the rate of AMs between OSA+ and OSA- groups. AMs were defined as a chin-lift, modified mask ventilation, nasal airway, bag-mask ventilation and endotracheal intubation. We report the rate of SRC, defined as any duration of pulse oximetry (SaO2) <90% or systolic blood pressure (SBP) <90mmHg, need for ≥1 AMs, or premature termination of the procedure. Univariate and multivariate analyses for predictors of AMs are presented as odds ratios (OR)
AGA Abstracts
S-640
polyps was surveillance from history of colorectal cancer (29.3%; OR=0.68; (95% CI, 0.670.69), followed by heme-positive stool (24%; OR= 0.51; (95% CI, 0.50-0.52), followed by iron deficiency anemia (23%; OR= 0.48, (95% CI, 0.47-0.49). Procedures done for screening revealed the least rate of cancer (0.13%; OR= 0.12; (95% CI 0.11-0.14) and Colonoscopies done for the purpose of abdominal pain showed the lowest rate of polyps (16.5%; OR=0.3; (95% CI 0.3-0.32) Native Americans undergoing screening colonoscopy were found to have the highest rate of colon cancer (0.43%) as compared to other ethnicity groups. Conclusions: Colonoscopic findings of colon cancer was highest among patients who presented with iron deficiency anemia, abdominal mass and positive FOBT.Native Americans undergoing screening colonoscopy had the highest rate of colon polyps and cancer.
with 95% confidence intervals (CI). Results: Over 11 months, 231 patients were enrolled (176(76%) ERCP and 55(24%) EUS). SRC included SaO2 <90% (6.9%), SBP <90mmHg (15.1%), premature termination of the procedure (0.9%), and ≥1AMs (12.1%). Bag-mask ventilation was required in 1.2%. There were no cases requiring endotracheal intubation. 152 (65.8%) patients met criteria for OSA+. The frequency of AMs was significantly higher among OSA+ (15.8%) compared to OSA- (5.1%) patients (OR 3.5 [1.2-10.5]). On univariate analysis, other clinical features (ASA class, Mallampati score) and procedure characteristics (prone position, induction or total propofol dose, endoscopy time) were not predictive of AMs. Regression analysis including each component of STOP-BANG revealed the strongest independent predictor of AMs was a history of witnessed apnea while sleeping (OR 5.9 [1.8-19.6]). Conclusion: Among patients undergoing advanced endoscopy, 65.8% of patients were high risk for OSA. Using a bedside screening tool, patients classified as high risk are more likely to require AMs during advanced endoscopy. W1050 Prospective Evaluation of Graft Versus Host Disease (GVHD) in the Gastrointestinal (GI) Tract to Determine the Optimal Biopsy Site for Diagnosis: Looking for a Smoking Gun in a Haystack Ethan D. Miller, Giovanni DePetris, Roberta H. Adams, Michael D. Crowell, Deloris K. Hutt, Mashal J. Batheja, Juan F. Gallegos-Orozco, Nancy J. Han, J. C. Hernandez, Jonathan A. Leighton, Hack J. Kim, Jose F. Leis, James L. Slack, G. A. Decker GVHD is a common complication of allogeneic stem cell transplantation (SCT), and is a significant cause of post-SCT mortality. Signs and symptoms of GI GVHD are non-specific (e.g., nausea, vomiting and diarrhea). It is critical to differentiate GVHD from other causes, since its treatment entails steroid administration and is associated with risks. Endoscopicallyobtained mucosal biopsies are used for histological confirmation when GI GVHD is suspected. The biopsy site with the highest yield is not known, although some reports have favored the rectal mucosa. AIM To compare the diagnostic yield of biopsies obtained from different sites in the GI tract in patients with suspected GVHD. METHODS IRB approval was obtained. SCT recipients at Mayo Clinic Arizona suspected of having GI GVHD were identified. Each patient underwent an esophagogastroduodenoscopy (EGD) and flexible sigmoidoscopy (FS). Mucosal biopsies were collected in a standardized fashion from each of the following sites, regardless of mucosal appearance: gastric antrum, gastric body, duodenum, and rectum. Pathologists reviewed the specimens and diagnosed GVHD based on the presence of apoptosis and/or crypt drop-out that could not be otherwise explained. Immunohistochemistry for cytomegalovirus (CMV) was also performed. RESULTS Twenty-two SCT recipients (median age 58.5, 11 women) underwent EGD and FS per protocol. Symptoms included nausea (77%); vomiting (64%); diarrhea (68%); abdominal pain (50%); and rectal bleeding (4.5%). Endoscopic findings ranged from normal mucosa to focal erythema or erosions. There were no complications. CMV was negative in all specimens. Histological findings suggested GVHD in 19 of 22 patients (86%). The diagnostic yields of EGD and FS biopsies were 68.2% (15/ 22 patients) and 72.7% (16/22 patients), respectively (p=NS). Neither the mucosal appearance nor symptoms predicted histology. In 3 patients (13.6%) the diagnosis was made by EGD alone, and in 4 patients (18.2%) the diagnosis was made by FS alone. The level of agreement between: (1) any EGD and FS biopsy results was 68% (95% CI, 47-84%); (2) gastric antral and rectal biopsy results was 41% (95% CI, 23-61%); (3) gastric body and rectal biopsy results was 36% (95% CI, 20-57%); and (4) duodenal and rectal biopsy results was 68% (95% CI, 23-61%). There were no cases in which gastric biopsies were positive but duodenal biopsies negative. CONCLUSIONS Contrary to previous reports, this study suggests that both EGD and FS may be necessary to reliably identify GI GVHD. For EGD, gastric biopsies do not add to the yield of duodenal biopsies.
W1048 Safety of Nurse Administered Propofol Sedation (NAPS) in ERCP Gregory A. Cote, John M. DeWitt, Evan L. Fogel, Glen A. Lehman, Lee McHenry, James L. Watkins, Stuart Sherman Background: While the safety of registered nurse (RN) administered propofol sedation (NAPS) in standard endoscopy is well established, there are limited data using NAPS for patients undergoing ERCP. Objective: Determine the safety of NAPS in patients undergoing ERCP at a tertiary medical center. Methods: Standard practice in ERCP at our institution is to use combination intravenous (IV) benzodiazepine and opiate (meperidine or fentanyl) with or without low dose droperidol. When a RN trained in NAPS was available, propofol was either used as: 1) “rescue” for patients failing to achieve adequate sedation with standard medications, or 2) with balanced propofol sedation (BPS), defined as propofol with low doses of combination IV benzodiazepine and opiate. Patients undergoing ERCP between May, 2007 and November, 2009 who received propofol in a NAPS protocol were identified in an endoscopy database. Propofol was administered by an ACLS-certified RN who had previously completed a training program in NAPS. The RN, under the supervision of the treating endoscopist, administered IV propofol in incremental doses of 10-40mg, titrating to achieve moderate or deep sedation. Capnography was not used for supplemental monitoring. Sedation-related complications (SRCs) included hypoxemia (pulse oximetry < 90%), decline in systolic blood pressure > 25% from baseline or < 90mmHg, aspiration, bag-mask ventilation, and premature termination of the procedure. Data are reported as medians with interquartile ranges. Results: 71 patients (median age 47 (37-54), 63% females) were identified. ASA class ≥3 was reported in 6 (8%). Indications included biliary obstruction in 28 (39%), suspected sphincter of Oddi dysfunction in 16 (23%), and removal of a pancreatic duct stent in 13 (18%). Endoscopic drainage of a pancreatic pseudocyst was performed in 5 (7%) cases of combined ERCP and EUS. Median endoscopy time was 28 minutes (1939). Sedation medications included a median total propofol dose of 220mg (130-370), midazolam 2mg (2-4) and either meperidine 50mg (50-75) or fentanyl 50mcg (50-75). Droperidol was used in 8 (11%) cases (median dose 6mg (5-7)). SRCs were identified in 3 of 71 (4%), including hypoxemia in 2 and transient hypotension in 1. One case required transient bag-mask ventilation and premature termination of the procedure. There were no cases of aspiration, and neither vasopressors nor endotracheal intubation were required. Conclusion: The frequency of SRCs using NAPS in ERCP is low (4%). In addition to being an effective “rescue” sedative for refractory patients, BPS appears feasible in ERCP. Larger studies are needed to verify these results.
W1051 Adherence to Surveillance Interval Guidelines in Barrett's Esophagus (BE): Analysis From a Large Multicenter Cohort Study Neil Gupta, Amy Wang, Patrick E. Young, Sachin B. Wani, Ajay Bansal, Keng-Yu Chuang, Hemanth Gavini, Vikram Boolchand, Priti Sud, John Kuczynski, Srinivas Gaddam, Vikas Singh, Mandeep Singh, April D. Higbee, Brooks D. Cash, Amit Rastogi, Sharad C. Mathur, David A. Lieberman, Gary W. Falk, Richard E. Sampliner, Prateek Sharma
W1049
Background: Despite the controversies, BE surveillance is commonly practiced in the US. However, data on adherence to surveillance interval guidelines are limited. Aim: To determine adherence rates for surveillance interval guidelines in BE patients managed at veteran and non-veteran tertiary care centers. Methods: A multi-center (5 centers) BE cohort database was analyzed. Diagnosis of BE required histologically confirmed intestinal metaplasia. Patients with no dysplasia (NDBE) or low grade dysplasia (LGD) at index endoscopy were included. Adherence was defined as a repeat endoscopy within 1-3 years of diagnosis for NDBE and 6-12 months for LGD. The following variables were included in the analysis: age, gender, race, BE length, study site, and date of diagnosis. Fisher's exact test and an unpaired t-test were used to compare categorical and continuous variables, respectively. Factors significant on univariate analysis were examined using a stepwise, multivariate logistic regression model to examine predictors for adherence. Results: A total of 2080 BE patients were diagnosed between October, 1990 - October, 2006 [NDBE (1788, 86.0%), LGD (292, 14.0%)]. Of these patients, 1236 (59.4%) underwent repeat surveillance endoscopy within the intervals defined above. Adherence rates were significantly higher in patients with LGD compared to NDBE (67.5% vs. 58.1%, {p = 0.003}), males vs. females (60.7% vs 49.8% {p =0.001}), and veterans vs. non-veterans (69.0% vs. 47.8%, {p<0.001}). Mean BE length was significantly longer in patients who were adherent compared to those not adherent (4.1cm vs. 3.7cm, p=0.0377). No differences in adherence rates were seen based on race, age, or decade of diagnosis. In the multivariate analysis, presence of LGD [OR 1.35 (95% CI 1.01 - 1.81), p=0.039], BE length [OR 1.06 (95% CI 1.03 - 1.10), p<0.001], and veteran status [OR 2.82 (95% CI 2.30 - 3.46), p<0.001) were independent predictors for adherence. Conclusions: Despite published guidelines for BE surveillance, overall adherence rates were low even at centers with expertise in BE. Patients with LGD, longer BE length, and veterans were more likely to undergo surveillance. Future studies should evaluate patient and physician factors affecting adherence to BE surveillance guidelines.
Prevalence of Obstructive Sleep Apnea Among Patients Undergoing Advanced Endoscopic Procedures Using Crna-Administered Propofol for Sedation: Use of a Beside Screening Instrument to Predict Sedation-Related Complications Gregory A. Cote, Christine E. Hovis, Robert M. Hovis, Lawrence Waldbaum, Riad R. Azar, Dayna S. Early, Steven A. Edmundowicz, Daniel Mullady, Sreenivasa S. Jonnalagadda Background: A majority of patients with obstructive sleep apnea (OSA) remain undiagnosed. Among patients undergoing advanced endoscopy (ERCP, EUS), unrecognized OSA is likely to be a predictor of sedation-related complications (SRC), particularly the need for airway modifications (AMs). Objective: Using an OSA screening tool, define the prevalence of OSA in patients undergoing advanced endoscopic procedures and correlate with the frequency of AMs. Methods: Consecutive patients undergoing ERCP and EUS were enrolled. Propofolbased sedation and patient monitoring were performed by a certified registered nurse anesthetist (CRNA) and an anesthesiologist. A previously validated screening tool, STOP-BANG, which includes 4 questions and 4 clinical features (age >50, male sex, BMI >35kg/m2, neck circumference >40cm) was completed prior to the endoscopy to assess OSA risk. Scores ≥3 of 8 have high sensitivity and negative predictive value for moderate to severe OSA. For improved specificity, we defined high risk for OSA as a STOP-BANG of >3 (OSA+). Primary outcomes were to define the frequency of OSA+ patients and compare the rate of AMs between OSA+ and OSA- groups. AMs were defined as a chin-lift, modified mask ventilation, nasal airway, bag-mask ventilation and endotracheal intubation. We report the rate of SRC, defined as any duration of pulse oximetry (SaO2) <90% or systolic blood pressure (SBP) <90mmHg, need for ≥1 AMs, or premature termination of the procedure. Univariate and multivariate analyses for predictors of AMs are presented as odds ratios (OR)
AGA Abstracts
S-640