Intravenous Fluid Administration in Patients Undergoing Colonoscopy: Double Blind, Randomised Clinical Trial of Underlying Acid-base Derangement

This is a prospective, double-blinded, randomized control trial. The study enrolls 90 consecutive outpatients, well-prepared bowel, scheduled to undergo routine colonoscopy for screening, surveillance, or diagnosis of colorectal diseases. At the outpatient clinic, the co-researcher invites patients who meet the inclusion criteria to join the study. The process of the project is explained to the interested patients in details before an informed consent is obtained and the first blood sample is conducted.

On the day of colonoscopy, all participants are randomized equally into three groups: Normal saline solution (NSS, n = 30) as control group, lactated Ringer's solution (LRS, n = 30) and acetated Ringer's solution (ARS, n = 30) as treatment groups. The second blood sample is obtained from patients via 20-gauge needle in either forearm immediately before an allocated intravenous (IV) fluid administered on the same site. The volume of fluid is calculated by means of Holliday and Segar formula.

The colonoscopy under total intravenous anesthesia is performed between 9:00 a.m. and 3:00 p.m. At the end of colonoscopy, the patients spontaneously wake up in the recovery room. After they gain conscious and all vital signs are stable; the intravenous fluid is off and the third blood sample is taken in the other forearm. After completion of the procedure, the patient is advised to follow the discharge instructions.