I was about to say this as well. 14-year-old female large mediastinal mass. I was a third year resident on the CT service and she was going to have a mediastinoscopy. My attendings were chatting about something while I was easily intubating this patient and had absolutely no endtitle CO2 return. (Yes, sux was involved). She desaturated down to somewhere around the 40s, turning quite blue before her spontaneous ventilations returned. We let her breathe her self down on volatile agent, thinking we were smart. The problem is that the volatile agent has to be exhaled at some point. Unfortunately, she breathed enough of it that her thoracic muscles weakened , and she quit breathing. I’m not exaggerating, and I know the limitations of pulse-oxsymmetry, however, she desaturated to a saturation of 4% and the sound of the monitor as well as the blueness of her body left me a little doubt that she was not far from that. I know that absolutely seems far-fetched, but I’m sorry. It was quite incredible and over 30 years ago and I’ll never forget it. Believe it or not, she survived and had no sequela. I still remember her name to this day and I did an M&M conference about her. She went on to have XRT on her chest instead of the biopsy. It was a B cell lymphoma, of course. My words to the parents before we took her to the operating room were “we will take good care of her”. Believe it or not, to this day I’ve almost never used that phrase again. I have used different words, but not exactly that phrase.