Water Exchange Colonoscopy in Elderly Patients: A Prospective Randomized Controlled Trial

To evaluate the clinical value of non-anesthesia water exchange colonoscopy in elderly patients and compare it with anesthesia water exchange, non-anesthesia gas insufflation, and anesthesia gas insufflation.

Methods: This was a single-center, prospective, randomized controlled trial that enrolled 200 patients aged 55 years or older undergoing colonoscopy between November 2024 and December 2025. Participants were randomly assigned (1:1:1:1) using a random number table to four groups (n=50 each): non-anesthesia water injection (NW), non-anesthesia gas insufflation (NA), anesthesia water injection (AW), and anesthesia gas insufflation (AA). All procedures were performed by an experienced endoscopist using a high-definition colonoscope (Olympus CF-HQ290I). Bowel preparation used standard polyethylene glycol electrolyte powder. In water injection groups, warm water at 37°C was injected through the biopsy channel during insertion, with suction of gas and fluid as needed. In gas insufflation groups, conventional air insufflation was used. Anesthesia groups received intravenous propofol combined with a small amount of opioid, administered by an anesthesiologist with continuous vital sign monitoring. The non-anesthesia groups received no anesthesia or analgesia.

Outcomes: The primary outcomes included maximum pain score during examination measured by a 10-point visual analog scale (VAS), cecal intubation time (minutes from insertion to identification of the ileocecal landmark), and serum levels of inflammatory and pain mediators (IL-1β, IL-6, and PGE2) measured by ELISA before and during colonoscopy. Non-inferiority of AW versus NW was assessed for inflammatory mediator inhibition using pre-specified margins. Statistical analysis used SPSS 25.0, with one-way ANOVA, Tukey HSD test, chi-square test, and non-inferiority testing; P<0.05 was considered statistically significant.