Use of nitrous oxide is contraindicated in all of the following surgeries except:
Cochlear implant
Microlaryngeal surgery
Vitrioretinal surgery
Exentration operation
D.i.e. Excentration operation Diffusion hypoxia is seen during recovery phase after discontinuation of prolonged N20 anesthesia. It can be prevented by continuing 100% 02 inhalation for a few minutes after discontinuing N20Q. Second gas effect occurs in initial pa of induction of N20 anesthesia. N20 also shows bone marrow suppressionQ. Excentration is enucleation + wide dissection of periorbital tissue. In it there is no closed space formation so N20 can be used. In microlaryngeal lesser surgery, N20 is contraindicated d/t risk of airway fireQ