<prompt> At the end of anaesthesia after discontinuation of nitrous oxide and removal of endotracheal tube, 100 oxygen is administered to the patient to preventDiffusion HypoxiaSecond gas effectHyperoxiaBronchospasm  <response>: Diffusion hypoxia can be prevented by continuing 100 O2 inhalation for a few minutes after discontinuing N2O, instead of straight away switching over to air. 