Can Visual Distraction Decrease the Dose of Patient-Controlled Sedation Required During Colonoscopy? A Prospective Randomized Controlled Trial - Lee, D W H; Chan, A C W; Wong, S K H; Fung, T M K; Li, A C N; Chan, S K C; Mui, L M; Ng, E K W; Chung, S C S (Endoscopy, 2004)