Carbon dioxide insufflation or warm-water infusion versus standard air insufflation for unsedated colonoscopy: A randomized controlled trial

Arnaldo Amato, Franco Radaelli, Silvia Paggi, Alessandra Baccarin, Giancarlo Spinzi, Vittorio Terruzzi

Research output: Contribution to journalArticle


BACKGROUND: The increasing demand for colonoscopy has renewed the interest for unsedated procedures. Alternative techniques, such as carbon dioxide insufflation and warm-water infusion, have been advocated to improve patient tolerance for colonoscopy in comparison with air insufflation. OBJECTIVE: The aim of this study was to evaluate the benefits of carbon dioxide insufflation and warm-water irrigation over air insufflation in unsedated patients. DESIGN: This study was a randomized, controlled trial. SETTING: This study was conducted at a nonacademic single center. PATIENTS: Consecutive outpatients agreeing to start colonoscopy without premedication were included. INTERVENTIONS: Patients were assigned to either carbon dioxide insufflation, warm-water irrigation, or air insufflation colonoscopy insertion phase. Sedation/ analgesia were administered on patient request if significant pain or discomfort occurred. MAIN OUTCOME MEASURES: The primary outcome measured was the percentage of patients requiring sedation/analgesia. Pain and tolerance scores were assessed at discharge by using a 100-mm visual analog scale. RESULTS: Three hundred forty-one subjects (115 in the carbon dioxide, 113 in the warm-water, and 113 in the air group) were enrolled. Intention-to-treat analysis showed that the proportion of patients requesting sedation/ analgesia during colonoscopy was 15.5% in the carbon dioxide group, 13.2% in the warm-water group, and 25.6% in the air group (p = 0.04 carbon dioxide vs air; p = 0.03 warm water vs air). Median (interquartile range) scores for pain were 30 (10-50), 28 (15-50), and 46 (22-62) in the carbon dioxide, warm-water, and air groups (carbon dioxide vs air, p <0.01; warm water vs air, p <0.01); corresponding figures for tolerance were 20 (5-30), 19 (5-36), and 28 (10-50) (carbon dioxide vs air, p <0.01; warm water vs air, p <0.01). LIMITATIONS: This investigation was limited because it was a single-center study and the endoscopists were not blinded to randomization. CONCLUSIONS: Carbon dioxide insufflation was associated with a decrease in the proportion of patients requesting on-demand sedation, improved patient tolerance, and decreased colonoscopy-related pain in comparison with air insufflation. The findings regarding warm-water irrigation confirmed the previously reported advantages, so that warm-water irrigation and carbon dioxide insufflation could represent competitive strategies for colonoscopy in unsedated patients.

Original languageEnglish
Pages (from-to)511-518
Number of pages8
JournalDiseases of the Colon and Rectum
Issue number4
Publication statusPublished - Apr 2013



  • Carbon dioxide colonoscopy
  • Unsedated colonoscopy
  • Water-aided colonoscopy

ASJC Scopus subject areas

  • Gastroenterology

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