914Patient-Controlled Analgesia With Inhaled MethoxyfluraneVersus Conventional Sedation for Colonoscopy: A Randomized,Multi-Centre TrialNam Q. Nguyen*1, Leanne Toscano1, James Moore2,Matthew Lawrence2, Richard H. Holloway1, William Tam1,Ian C. Roberts-Thomson3, Ilmars Lidums3, Venkataswamy N. Mahesh1,Carly M. Burgstad1, Tamara L. Debreceni1, Melissa Neo1,Mark Schoeman1

1Gastroenterology & Hepatology, Royal Adelaide Hospital, Adelaide,SA, Australia; 2Colorectal Surgery, Royal Adelaide Hospital, Adelaide,SA, Australia; 3Gastroenterology, The Queen Elizabeth Hospital,Adelaide, SA, AustraliaDiscomfort during colonoscopy is usually managed with combined intravenous(IV) benzodiazepine(s) and opioid(s), which may lead to unnecessary sedationand associated adverse events. Patient-controlled analgesia with inhaledmethoxyflurane (Penthrox®) has been used extensively in the community tomanage the pain associated with trauma. Penthrox® may be a more attractivealternative for managing the discomfort patients may experience duringcolonoscopy. Aims: To evaluate the efficacy, safety and post-operativemanagement of Penthrox® as an analgesic agent for performing colonoscopy ascompared to conventional sedation with IV benzodiazepine and opioid.Methods: 103 patients who were referred for colonoscopy were randomized toreceive either Penthrox® (P: n�48, 29M, 53�1.7yr) or IV midazolam andfentanyl (M&F: n�55, 33M, 53�1.9yr) as a method of discomfort relief duringcolonoscopy. Patients with renal and liver diseases were excluded. Details on thedegree of discomfort and anxiety before, during and after the colonoscopy wereassessed using the visual analogue scale (VAS) pain score and STAI Y-1 anxietyscore. Details on the performance of the colonoscopy as well as theoccurrence(s) of adverse events were also documented. Vital signs and oxygensaturation during the procedure were monitored every 5 minutes. Data wereanalyzed using Fisher’s exact test and Student’s t-test. Results: Age and genderwere similar between the two groups. In the sedation group, a mean dosage of3.4�0.1mg midazolam and 83.6�2.9mcg fentanyl was used. There were nodifferences in: procedural success rate (sedation vs Penthrox®: 54/55 vs. 47/48,respectively); hypotension during colonoscopy (4/55 vs. 7/48); tachycardia (3/55vs. 4/48); caecal arrival time (9.6�0.8 vs. 8.4�0.7 min) and polyp detection/polypectomy (19/55 vs. 18/48). Significant de-saturation (SaO2 �90%) was morecommon with sedation than with Penthrox® (4/55 vs. 0/48; P�0.05). Patientswith Penthrox® awoke earlier (1.5�0.4 vs. 11.1�2.5 min; P�0.001) and wereready to be discharged earlier than those with sedation (36.0�2.2 vs. 56.6�2.5min; P�0.001). Neither VAS pain nor STAI Y-1 anxiety scores before, during orimmediately after colonoscopy were different between groups. Conclusions:Patient-controlled analgesia with Penthrox® for colonoscopy is as effective asconventional sedation for relieving pain and anxiety without influencing theprocedural success and polyp detection rate. It appears safer with fewer eventsof oxygen de-saturation. Without the effects of sedation, patients with Penthrox®

analgesia are able to be discharged earlier which may facilitate early dischargeand improve the work flow of endoscopy units.

915Development of Novel Optical Technologies for Early ColonCarcinogenesis Detection via Nanoscale Mass DensityFluctuations: Potential Implications for Endoscopic DiagnosticsShailesh Bajaj*1, Ji Yi2, Andrew Radosevich2, Michael J. Goldberg1,Jeremy D. Rogers2, Laura K. Bianchi1, Eugene F. Yen1,Sudeep Upadhye1, Tat-Kin Tsang1, Beth Parker1, Hemant K. Roy1,Vadim Backman2

1GI/Medicine, NorthShore University HealthSystems, Evanston, IL;2Biomedical Engineering, Northwestern University, Evanston, ILOur group has been at the forefront of developing light scattering technologies(Nature 2000, Nat Med 2001, Gastro 2004, Clin Cancer Res 2006) and we haveapplied to cancer screening (reviewed in Gastro 2011). Our suite of technologiesare sensitive to particle sizes from 50-500 nm thereby providing unprecedentedinsights into the nano-structural consequences of the genetic/epigeneticalterations in field carcinogenesis (Clin Cancer Res 2007, Gastro 2008, CancerRes 2009). To maximize diagnostic performance, two critical issues need to beaddressed, 1. Optimal depth to interrogate 2. Cells to target (crypt versusstromal). To address these issues we developed two new technologies. Depthwas assessed via the tomographic functionality of low coherence enhancedbackscattering spectroscopy (LEBS). To identify cells of origin, we inventedinverse scattering optical coherence tomography (ISOCT) which allowsderivation of the mass density correlation function . Methods: 82 patientsundergoing screening /surveillance colonoscopy had two biopsies from theendoscopically normal rectal mucosa. Optical analysis was performed byinvestigators blinded to clinical data. The rectal biophotonic analysis was used todetermine the difference in markers between controls (those with a negative

colonoscopy) and patients harboring either advanced adenomas (�1cm, �25%villous features or high grade dysplasia) or non-advanced adenomas (“effectsize”�(neoplasia- control)/SD). Results: Tomographic LEBS: We evaluateddepth with a novel tomographic approach to LEBS. We evaluated penetrationdepth at progressively deeper LScs, and also measured LEBS enhancement whichdecreases early in field carcinogenesis (Cancer Res 2009). We noted the mostrobust effects appeared to be at superficial depths (Figure 1).ISOCT: In order toexamine the epithelial versus stromal contributions, we used ISOCT to measuremarkers on crypt versus off crypt. We calculated all relevant tissuecharacteristics. Figure 1, we evaluated a derivative of spectral slope (a marker ofsubmicron particle size heterogeneity) which we had previously shown to berelated to neoplasia (Dis Col Rect 2009). We observed (figure 2) with thepseudo-color map that the greatest alterations were from the crypt, with the non-crypt site (stroma) showing more modest effects. Conclusions: We demonstratethat in early colon carcinogenesis, the nano-architectural changes arepreferentially located in the cryptal structures at shallow (epithelial) depths. Thisstudy also underscores the power of combining two novel optical technologies,tomographic LEBS with ISOCT, for probing the nanoscale architecturalalterations. In the future, these can be coupled with an endoscopicallycompatible fiberoptic probes in order to both detect dyplasia and also neoplasticrisk through field carcinogenesis identification.

916Accuracy of In Vivo Colorectal Polyp Discrimination Using DualFocus High Definition Narrow Band Imaging Colonoscopy: ARandomized Controlled Trial; Preliminary ResultsSusan G. Coe*, Cristina Almansa, Julia Crook, Mihir K. Patel,Nancy Diehl, Estela G. Staggs, Vivian Ussui, Ernest P. Bouras,Andrew Keaveny, Michael F. Picco, Douglas Riegert-Johnson,Herbert C. Wolfsen, Michael B. WallaceMayo Clinic, Jacksonville, FLBackgrounds: Advances in in-vivo imaging of colorectal polyps has opened thepotential to replace histology for confirmation of small polyps with lowmalignant potential. Such a strategy could substantially reduce the cost ofcolorectal cancer prevention. The ASGE recently set threshold accuracy for polypclassification (�90% NPV for adenoma), and surveillance interval predication (�90% accuracy) before such a “diagnose and discard” strategy could be adopted..Current methods such as chromoendoscopy and optical enhancement, includingNarrow Band Imaging (NBI) have not generally met these thresholds. Zoomendoscopy has been shown to meet thresholds but is impractical in mostsettings. Aim: The aim of this study was to determine the accuracy of polypclassification comparing currently available HD-NBI systems (Olympus 180) to apre-commercial next-generation system (Olympus 190) with NBI, pre-freezeimage capture and dual focus high definition imaging (DFHD) in near mode ornormal mode by a control button on the endoscope handle.Methods. Patientsundergoing colonoscopy for screening or surveillance were randomized tostandard HD-NBI imaging or DFHD-NBI colonoscopy. White light (WL) imagingwas used in both arms for polyp detection. HD-WL and HD-NBI were used inthe 180 arm, and near mode DFHD-WL and DFHD-NBI were used in the 190arm for polyp classification using the NICE classification. The reference standardwas the histological diagnosis by the clinical pathologist. The sample size was600 patients randomized 1:1 to each arm. Six experienced staff endoscopists

Figure 1. ISOCT Analysis of Rectal Spectral Markers DemonstratingGreatest Effect at the Crypt.

Abstracts

www.giejournal.org Volume 75, No. 4S : 2012 GASTROINTESTINAL ENDOSCOPY AB172