Question: I too have just now have my N2 setup with scba mask and just did 2 trials. Not pleasant as yours. I was not nervous, yet heart rate raced rapidly and started to sweat profusely causing panic. No suffocation feeling with not being able to breath, but did not pass out, just felt physically ill. Even after I got fresh air a headache lingered for a day. (they said N2 was very high purity? ...I'm looking into a purity tester to see for myself). I'm hoping that can be remedied as I'm not looking to another trial if that is going to be my experience again.