Nitrous oxide: a valuable alternative for pain relief and sedation during routine colonoscopy

Patient-administered nitrous oxide in 50% oxygen has lately come into use as an alternative to combined opioid and benzodiazepine medication for colonoscopic procedures. A randomized study was carried out comparing intramuscular pethidine hydrochloride 1 mg/kg with inhalation of Medimix (a mixture of nitrous oxide in oxygen 50%) for relief of pain and anxiety during colonoscopy.

Thirty-eight patients (19 in the pethidine group and 19 in the nitrous oxide group) were studied. The following parameters were measured: blood pressure, pulse rate, and arterial oxygen saturation. At the end of the colonoscopy and before the patients left the ward, pain, nausea, and general well-being were evaluated by the patients using a visual analogue scale. The colonoscopy time, investigation conditions and the total length of hospital stay were registered.

Colonoscopy time and the colonoscopists' opinions concerning the investigation conditions did not differ between the groups. Pain relief and patient evaluation of the total procedure were also equal between the patient groups. However, there was less nausea among the Medimix patients. Three patients in the pethidine group had oxygen saturations below 92%. There was no desaturation during and five minutes after colonoscopy in the Medimix group. Patients in the Medimix group left the hospital on average 34 minutes earlier than patients in the pethidine group.

We conclude that the use of nitrous oxide (Medimix) as an analgesic is as good as pethidine for colonoscopy. Medimix has clear advantages compared to pethidine in terms of reducing nausea and shortening the hospital stay.