The effects of highly concentrated oxygen flow rate changes on the blood oxygen saturation and heart rate of young and elderly subjects

This study investigated the differences in blood oxygen saturation (SpO(2)) and heart rate (HR) related to flow rate, age, and phase in subjects in their 20s and 60s when the supply of highly concentrated (93%) oxygen was varied (1 L/min, 3 L/min, and 5 L/min). Ten males (25.0 +/- 1.8 years) and ten females (23.7 +/- 1.9 years) in their 20s and ten males (68.0 +/- 2.6 years) and ten females (65.5 +/- 3.1 years) in their 60s participated in the study. The experiment consisted of three phases: Pre-Hyperoxia (5 min), Hyperoxia (10 min), and Post-Hyperoxia (10 min). SpO(2)[%] and HR [bpm] were measured during each phase. SpO(2) was higher in the Hyperoxia phase than in the Pre- and Post-Hyperoxia phases. A higher flow rate was associated with a more pronounced increase in SpO(2). The SpO(2) of subjects in their 20s was higher than that of subjects in their 60s, regardless of flow rate or phase; however, the rate of SpO(2) increase when transitioning from the Pre-Hyperoxia phase to the Hyperoxia phase was higher for that of subjects in their 60s than those in their 20s. HR was lower in the Hyperoxia phase than in the Pre- and Post-Hyperoxia phases. The HR of subjects in their 20s was higher than that of subjects in their 60s, regardless of flow rate or phase, and the rate of HR decrease from the Pre-Hyperoxia phase to the Hyperoxia phase was higher for subjects in their 20s than those in their 60s. However, flow rate did not cause a difference in HR.