Tu1562 Unsedated Colonoscopy: Patient Characteristics and Policy Change Analysis in the US Veteran Population

to significantly increase ADR while the water immersion method is the same as air insufflation method in ADR. Tu1561 Water Immersion Reduces Loop Formation As Effectively As Water Exchange, but Falls Short in Limiting Pain and Achieving Successful Cecal Intubation Joseph W. Leung*, Vyacheslav M. Vakulchik, Jianqiang Liu, Roy Silvernail, Jaymie Pearcy, Andrew W. Yen, Felix W. Leung Gastroenterology, Sacramento VA Medical Center, Mather, CA; Gastroenterology, UC Davis Medical Center, Sacramento, CA; Gastroenterology, Sepulveda ACC, VAGLAHS and David Geffen School of Medicine at UCLA, North Hills, CA Background: Water immersion (WI) and water exchange (WE) rely on infusion of water to guide insertion of the colonoscope. WI and WE entail removal of infused water predominantly during scope withdrawal or during scope insertion, respectively. Meta-analysis showed that both minimize insertion pain with WE better than WI. Loop formation contributes to pain during colonoscopy. Magnetic endoscope imaging (MEI) provides display of scope configuration. Compared to air insufflation (AI), WE is associated with significantly less frequent MEI-demonstrated sigmoid looping (JIG 2012;2:142-146). The impact of WI on MEI-demonstrated loop formation has not been reported. Aim: Since WE reduced pain to a greater extent than WI, we test the hypothesis that WE induces loop formation in a significantly lower proportion of patients than WI. Method: WI and WE were implement by JWL as previously described. Consecutive patients were assigned to WI or WE with almost all of the unsedated ones assigned to WE by the assistant. The endoscopist was blinded to the MEI image during insertion. The MEI data were recorded, coded and randomly reviewed by 2 independent blinded observers (95% agreement in 100 cases). Sigmoid loop is defined as complete if the scope crosses itself, or partial with exaggeration of the sigmoid loop. Occurrence of sigmoid loop before/upon reaching the cecum was recorded. Loop reduction, abdominal compression and changing patient position were implemented as clinically indicated. The volumes of water infused to facilitate scope insertion, and suctioned during insertion were recorded. The main outcomes were occurrence of loops during insertion and looping at cecum. Results: Loop formation in 94 WE and 95 WI was compared to a historical control group of 32 AI patients (Table 1). Both WE and WI reduced looping compared with AI (39.4% vs. 34.7% vs. 62.5%), but there was no difference between WE and WI. WE had a significantly higher intention-to-treat (ITT) cecal intubation rate (99% vs. 82%) (Table 2). A significantly higher proportion of the WE group (25% vs. 1%) completed without sedation. The volume (ml) of water suctioned during insertion was significantly higher in the WE than WI group; 392 vs. 131, p!0.001 (hepatic flexure), 793 vs. 482, p!0.0001 (cecum). Limitation: This is a performance improvement project but not a RCT due to limited availability of the loaner MEI equipment. Conclusion: Compared to AI, WE and WI significantly reduced loop formation, but the data failed to support the proposed hypothesis. WI reduces loop formation as effectively as WE but falls short in achieving successful ITT cecal intubation. The reported greater reduction of pain by WE compared to WI (confirmed by current observations of a higher proportion of WE patients completing unsedated colonoscopy) cannot be full explained by attenuation of loop formation only. Table 1. Sigmoid loop formation demonstrated on MEI AB586 GA Water Exchange STROINTES Water Immersion TINAL ENDO Air Insuffaltion