Carbon Dioxide Insufflation or Warm-water Infusion for Unsedated Colonoscopy: A Randomized Controlled Trial in Patients with Chronic Constipation in China

AIMS: The effect of carbon dioxide (CO(2)) insufflation and warm-water infusion during colonoscopy on patients with chronic constipation remains unknown. We evaluated CO(2) insufflation and warm-water irrigation versus air insufflation in unsedated patients with chronic constipation in China. PATIENTS AND METHODS: This randomized, single–center, controlled trial enrolled 287 consecutive patients, from January 2014 to January 2015, who underwent colonoscopy for chronic constipation. Patients were randomized to CO(2) insufflation, warm-water irrigation and air insufflation colonoscopy insertion phase groups. Pain scores were assessed by the visual analog scale (VAS). The primary outcome was real-time maximum insertion pain, recorded by an unblinded nurse assistant. At discharge, the recalled maximum insertion pain was recorded. Meanwhile, patients were requested to select the VAS at 0, 10, 30, and 60 min after the procedure. In addition, cecal intubation and withdrawal time, total procedure time, and adjunct measures were recorded. RESULTS: A total of 287 patients were randomized. The correlation between real-time and recalled maximum insertion pain ((Pearson coefficient r = 0.929; P < 0.0001) confirmed internal validation of the primary outcome. The mean real-time maximum pain scores during insertion 2.9 ± 2.1 for CO(2), 2.7 ± 1.9 for water achieved a significantly lower pain score compared with air (5.7 ± 2.5) group (air vs CO(2) P < 0.001; air vs water P < 0.001). However, no significant pain score differences were found between the patients in the CO(2) and water groups (CO(2) vs water, P = 0.0535). P values in painless colonoscopy and only discomfort colonoscopy (pain 1–2) were, respectively, 6 (6.4%) and 8 (8.5%) for air; 17 (17.7%) and 29 (30.2%) for CO(2); 16 (16.5%) and 31 (31.9%) for water. At 0, 10, 30, and 60 min postprocedure, pain scores showed in the CO(2) and water groups had significantly reduced than in air group. Insertion time was significantly different between air (10.6 ± 2.5) and CO(2) (7.2 ± 1.4) (air vs CO(2) P < 0.001), air and water (6.9 ± 1.3) (air vs water P < 0.001). However, CO(2) and was not significantly different in cecum-intubated time (CO(2) vs water, P = 0.404). CO(2) and water group in extubation time were significantly different, respectively, CO(2) (7.9 ± 1.1) and water (8.0 ± 1.1) (CO(2) vs water, P = 0.707). CO(2) or water group required less implementation of adjunct measures and more willingness to repeat the procedure. CONCLUSIONS: Compared with air, the CO(2) or water-aided method reduced real-time maximum pain and cecum-intubated time for chronic constipated patients in unsedated colonoscopy. The CO(2) insufflation or warm-water irrigation may be a simple and inexpensive way to reduce discomfort in unsedated patients with constipation. This study demonstrated an advantage of using CO(2) insufflation and warm-water irrigation during colonoscopy in unsedated constipated patients in China.