To the Editor:
In the article, “Postexercise Peripheral Oxygen Saturation After Completion of the 6-Minute Walk Test Predicts Successfully Reaching the Summit of Aconcagua,” 1 the authors reported a useful screening test to identify climbers with a very low likelihood of success. Postexercise peripheral oxygen saturation (Sp02) in successful summiters was 80.8%, in nonsummiters it was 76.4%, but in those with a SpO2 of <75%, only 1 of 10 made it to the top and back.
Two-thirds of subjects enrolled 12 to 24 hours after arrival at base camp (4364 m). The authors rightly stated that prior acclimatization could affect performance. High altitude illness, by definition, begins at 2438 m and the standard Horcones route begins at 2850 m. It was hoped that climbers had spent a prior night or two nearby. Arrivals 2 or 3 days later at base camp (4364 m) were still in their first few days of acclimatization to higher and higher camps. It was no surprise that some of them mildly desaturated with exercise during the study. Medical conditions, illness, age, or poor conditioning may have been responsible for some of those results, but perhaps much of this was early, unrecognized, subclinical, and/or reversible high altitude pulmonary edema with or without other symptoms of acute mountain sickness.
Here is my question: The authors propose using the screening test to caution new arrivals, in part for their safety, that their chances of summiting are slim if their postexercise Sp02 is <75%. But need that warning be permanent? What if they are advised not to continue on “at their own pace” but, rather, to come back the next day (or at some time during the next several days) until they pass the test? Rather than using the test as “pass-fail” on that one day alone, it would be interesting to know how many of those first-day failures might improve with longer stays at the same altitude, thus improving acclimatization and the odds for eventual success. Serial testing and climbers' cooperation is needed, of course, to answer this.