Prefixed equimolar nitrous oxide and oxygen mixture reduces discomfort during flexible bronchoscopy in adult patients: a randomized, controlled, double-blind trial.

STUDY OBJECTIVES Flexible bronchoscopy (FB) is an invasive procedure associated with patient discomfort and frequent nose pain. A simple sedation procedure that does not require the intervention of an anesthetist is of interest. The aim of this prospective, randomized, double-blind study was to assess efficiency of nitrous oxide inhalation on the reduction of FB-induced discomfort in adult patients. DESIGN AND SETTINGS Two hundred six patients were randomized to receive either a prefixed equimolar nitrous oxide/oxygen mixture (N2O) or a prefixed equimolar nitrogen and oxygen mixture (control). The primary outcome was stress as assessed by pulse rate and systemic BP during the procedure. Secondary outcomes were self-assessed pain using a visual analog scale (VAS) and patient satisfaction based on a questionnaire. Adverse events were recorded. RESULTS A significant increase in BP was observed only in the control group (p = 0.003), while pulse rate values did not differ between the two groups. As assessed by the VAS, pain was lower in the N2O group as compared to placebo (p = 0.02). Nose pain and cough were also significantly reduced by N2O. Adverse events, mostly anxiety, were reported in 10 patients. CONCLUSION These results indicate that equimolar N2O inhalation is efficient in reducing patient discomfort and may be an alternative to general anesthesia.