Effects of micro-pressure oxygen, diffuse oxygen supply, and nasal cannula oxygen on hematological and psychological outcomes in high-altitude migrants: a randomized controlled trial

Background Direct comparisons of oxygen-delivery approaches in healthy high-altitude migrants remain limited. This study compared the effects of micro-pressure oxygen, diffuse oxygen supply, and nasal cannula oxygen on oxygenation, heart rate, hematological indices, and depressive symptoms in healthy university students living in Lhasa. Methods Eighty healthy university students who had migrated from low-altitude areas to Lhasa (3650 m) were randomized equally to three oxygen interventions or a no-intervention control; 75 were included in the final analysis. The intervention lasted 20 days. Peripheral oxygen saturation (SpO 2 ), heart rate (HR), hemoglobin (Hb), hematocrit (Hct), and Symptom Checklist-90 depression scores were assessed before and after intervention. Group-by-time interactions in 4-group × 2-time mixed ANOVAs were the primary omnibus tests; between-group change-score comparisons characterized intervention responses. Results Significant group-by-time interactions were observed for all five outcomes. Compared with control, micro-pressure oxygen and nasal cannula oxygen produced greater increases in SpO 2 and reductions in HR. All three interventions produced greater reductions in depression scores. Nasal cannula oxygen produced a greater reduction in Hb, while micro-pressure oxygen and nasal cannula oxygen produced greater reductions in Hct. Although SpO 2 increased from baseline with diffuse oxygen, its change did not differ significantly from control. No adverse events were observed. Conclusions The regimens showed different outcome-specific response patterns, without establishing an overall superior approach. Reductions in Hb and Hct should not be assumed to indicate clinical benefit. These findings apply to healthy university students who have migrated to high-altitude. Further research is needed to determine whether similar differences occur in patients with acute mountain sickness.