Minute 0. The guide stops the trek and sits the client in a sheltered position. Supplemental oxygen is administered at 2–4 L/min. A second SpO₂ reading is taken with a warmed finger to rule out a cold-finger error.
Minutes 1–30. The client remains seated with O₂. SpO₂ is checked at minute 10, minute 20, and minute 30. The guide assesses symptoms: headache, nausea, balance, coordination.
Minute 30 — Decision Point. If the reading is rising and symptoms are clearing, the trek continues at a reduced pace with hourly re-checks. If the reading has not improved, the group descends to the last lodge where the client had a stable reading. No exceptions.
