The execution took about 22 minutes from the time between the opening and closing of curtains to the viewing room. Smith seemed to remain conscious for several minutes. For at least two minutes, he appeared to shake and writhe on the gurney, sometimes pulling against the restraints
The execution could hardly be considered a success. The mask wasn’t sealed properly to his face and allowed oxygen to be inhaled as well. Nitrogen-execution requires a complete lack of other trace gasses to effectively asphyxiate without pain. This man suffered the equivalent of drowning for 22 minutes.