Bispectral Index Monitoring for Sedation in Elective Colonoscopies of Adult Patients: a Randomized Controlled Trial

Inclusion Criteria: * Indication of complete colonoscopy on a scheduled basis. * Classification of physical status ASA I, II and III, with the exception of patients with moderate to severe kidney and / or liver disease. * Intermittent or persistent mild asthma. It implies the absence of daily symptoms and FEV1\> 80% (GINA 2004). * Body Mass Index (BMI) less than 35 kg / m2, and greater than 18 kg/m2. * Intact neurological capacity. * Acceptance to participate in the study after the contribution of written informed consent. Exclusion Criteria: * ASA IV. * BMI greater than 35 kg / m2, and less than 18 kg/m2. * Refusal to participate in the study. * Allergy to any of the medications used in sedation, or its components. * Known mental or neurological disease. * Renal and / or moderate to severe Hepatic insufficiency. * Chronic Obstructive Pulmonary Disease (COPD) or Obstructive Sleep Apnea. * Chronic opiate users.