Erythrocytapheresis for Chronic Mountain Sickness

Inclusion: 1. Age ≥18 years; 2. High-altitude residents or long-term dwellers (continuous residence at ≥2500 meters above sea level for at least 1 year), with no travel history to low-altitude areas in the past 3 months; 3. Hemoglobin (Hb): Men: ≥210 g/L, Women: ≥190 g/L; at least one symptom or sign: headache, dizziness, dyspnea, palpitations, sleep disturbances, fatigue, localized cyanosis, burning sensation in palms/soles, venous dilatation, muscle/joint pain, loss of appetite, poor concentration, or memory changes; CMS total score ≥6; 4. Written informed consent obtained from patients or their legal representatives. Exclusion: 1. Hematocrit \< 60%; 2. Patients with erythrocytosis attributable to: polycythemia vera; secondary erythrocytosis due to dehydration, cyanotic congenital heart disease, or chronic obstructive pulmonary disease; or other underlying hematologic or oncologic conditions; 3. Patients with active pneumonia, pulmonary embolism, or severe organ dysfunction (including cardiac, hepatic, or renal failure); 4. Patients with contraindications to study procedures (including erythrocytapheresis, pulmonary function tests, or incremental shuttle walk test), such as impaired consciousness, pneumothorax, severe arrhythmia, or significant coagulation disorders; 5. Patients who have received CMS-specific interventions within the last 6 months, including phlebotomy, erythrocytapheresis, or targeted pharmacotherapy; 6. Patients currently pregnant, breastfeeding, or planning to become pregnant within 1 year; 7. Any terminal condition with an estimated life expectancy of \< 6 months; 8. Current participation in other clinical trials.