Fiberoptic bronchoscopy may generate pain, anxiety or cough and dyspnea. It may then induce discomfort and then run down its yield. Systematic local anaesthesia does not always suffice and FOB may be conducted under general anaesthesia. Premixed nitrous oxide and oxygen (MEOPA) could be efficient to avoid general anesthesia risks and to reduce organizational costs. Nitrous oxide induces anaelgesia and anxiolysis when administered in oxygen at a 50% concentration.