Health - Did Swim hold his breath too long?

[PlaneCrash]

for the first time today swim tried nitrous. he pushed a little of the air out of his lungs, and for ten seconds he inhaled nos, then he exhaled and breathed a breath or two of sobering atmosphere, before repeating the process 2 more times. he did two balloons like this, divided by the course of maybe 4 minutes. on his second round he took breaks of maybe 3 or four deep breaths of oxygen. swim isn't positive, but looking in the mirror after his second dose his lips may have appeared slightly blue, and then with heavy respiration reverted to luscious kroovy.

is 10 seconds long enough to kill brain cells? swim still feels off 7 hours later, and has heard reports of people holding the hit for 20+ seconds?