Just before the Christmas break, I convinced two friends to accompany me to Pittsburgh. My second altitude simulation test provided an excuse to explore the city after a stressful semester. I scheduled the test to see if I still need oxygen while flying. The test takes only 20 minutes. This time I did not need any supplemental oxygen! Last year I crossed the 88% oxygen saturation threshold within about 4 minutes. This year I was at 88% only briefly; whenever I saw the number drop below 90, I took a few deep breaths and watched it go back up. The respiratory therapist said I was right on the cusp of needing oxygen and that my doctor should decide. My pulmonologist was out of the office, so I took the portable with me on our trip to Minneapolis and monitored my sats. I did end up using it part-way into the flights because my levels were hovering in the mid-80s. Back to Pittsburgh: we had a fabulous lunch at Bao Buns (the pork soup dumplings were phenomenal) and followed my friend Ni...