A U.S. member climbing Aconcagua, the highest mountain in South America, was suffering from symptoms consistent with HAPE (high-altitude pulmonary edema). He was examined and treated with medications provided by physicians deployed to the mountain. Unfortunately, the member’s condition deteriorated overnight, and his oxygen saturation dropped to 59%, more than 30 percentage points below normal. Global Rescue medical operations was contacted. Due to the member’s worsening condition, Global Rescue operations personnel initiated a helicopter field rescue with immediate ground transport by ambulance to a hospital for evaluation.