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

Randomized double-blind clinical trial in patients undergoing scheduled colonoscopies in endoscopy rooms of the Galdakao-Usánsolo Hospital (Bizkaia, Spain) and Mendaro Hospital (Gipuzkoa, Spain). The investigators will compare the rate of cardiorrespiratory adverse events as well as the anesthetic drugs dosage, need for rescue medication and patient satisfaction among the experimental group in which sedation is guided by BIS and the control group in which the anesthesiologist is blind to the result of the BIS. The investigators hypothesized that BIS monitoring would be associated with better outcomes than clinical observation.

The BIS is the parameter of anesthetic depth monitoring most used today. Its use was approved by the Food and Drug Administration (FDA) in 1996 as an aid to control the effects of certain anesthetic agents. It is validated in the operating room (Recommendation grade A), but not outside it due to lack of conclusive studies.

180 patients are needed to obtain statistically significant differences between both groups. Qualitative variables are expressed in the form of frequencies and percentages and continuous variables in the form of means and standard deviations. Comparisons of percentages will be made by the Chi square test (or Exact Fisher's test, when the expected frequencies are less than 5) and the difference of means in the continuous variables by the t test as well as by the Wilcoxon nonparametric test if the distribution of the variable requires it. The degree of agreement between the BIS and Ramsay scale will be made through the weighted Kappa test. Statistical significance will be assumed when p <0.05. All statistical analyzes will be carried out using SAS V9.4. (SAS institute, Inc., Carey, NC).

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.