At our institution, we have many who use nitrous oxide at or near 70% for msot cases unless contraindicated, and those who never use it for any case because of nausea, gas-filled cavities, marrow depression and the fact that sevo and desflurane seem to make it unnecessary.

I hold the middle ground. I use nitrous for all cases (unless directly contraindicated) at 50%. I find this gives me the best of both worlds. 50% O₂ is plenty safety margin, yet the 50% nitrous allows for much quicker emergence (yep, even better than desflurane) and NO nausea side effects. I say NO in big letters because I am not entirely sure of this - I have no data to back it up. But informal feedback from my recovery nurses indicate that my patients have the fewest incidence of nausea out of all my peers.

I stand ready to be corrected, but I would need to see strong evidence in order to convince me to change my stance.