Randomised Controlled Trial of Sedation for Colonoscopy: Entonox Versus Intravenous Sedation

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Introduction: Intravenous sedation for colonoscopy is associated with cardio-respiratory complications, delayed recovery and prolonged drowsiness. We aimed to determine whether inhaled Entonox (50% nitrous oxide: 50% oxygen) provides adequate analgesia compared to Midazolam/Fentanyl and its impact on psychomotor recovery and patient satisfaction. Methods: All patients undergoing elective colonoscopy except those with history of colon resection were included. Ethics committee approval was obtained. Randomisation was stratified by endoscopist grade with adequate allocation concealment. The entonox group inhaled for 60 seconds before procedure and continued till the caecum was reached. In intravenous group, Fentanyl was followed by Midazolam and colonoscope was inserted 5 minutes thereafter. Patients completed anxiety score (HAD questionnaire), baseline letter-cancellation test and pain score on visual analogue scale (VAS) before procedure. Patients then completed letter-cancellation tests and marked pain assessment on VAS immediately after procedure and at discharge. All patients completed satisfaction survey at discharge and 24-hours post-procedure, when they also marked pain assessment. Secondary end-points measured were completion rates, nurse and endoscopist satisfaction and complication rates. Results: 120 patients were randomised to receive Entonox (n = 60) or Midazolam/Fentanyl (n = 60). None of entonox patients needed conversion to intravenous medication. Entonox patients reported significantly lesser pain (mean score 25 versus 40, p < 0.003; Mann Whitney U Test) with similar pre-procedure anxiety scores (p = 0.1). Pre-colonoscopy letter cancellation scores were similar, Entonox group patients scored significantly better than the intravenous group (p = 0.001) both immediate post-procedure and at discharge. Discharge time was significantly lesser for entonox patients (mean 26 minutes) than intravenous group (mean 44 minutes; p = 0.004). There was no significant difference in completion rates between two groups (96% versus 94%; p = 0.5). Patient satisfaction was higher in entonox group (mean 98 versus 80; p = 0.001). Conclusion: Entonox is more effective than midazolam/fentanyl for colonoscopy, provides greater patient satisfaction and facilitates early discharge. These findings have enormous socio-economic impact as faster psychomotor recovery implies patients do not need carer, can be allowed to drive home and are able to join work next day. The health service benefits with obvious lower costs and faster turnover.