Advanced Age and Sex Influence Baseline Regional Cerebral Oxygen Saturation as Measured by Near-Infrared Spectroscopy: Subanalysis of a Prospective Study

(eng) OBJECTIVES: The aging brain shows decreased venous oxygenation predominantly in the frontal cortex, which seems sex- dependent. The authors hypothesized that age and sex would influence baseline regional cerebral oxygen saturation (rScO2) measured by the INVOS 5100. DESIGN: Subanalysis of published data. SETTING: Tertiary hospital. PARTICIPANTS: A total of 1,616 adults undergoing cardiac interventions. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Baseline rScO2 was recorded at room air and calculated as mean of the left and right rScO2. Patients were divided into 3 groups: 18- to- 49 years: young; 50- to- 74 years: middle-aged; and ≥75 years: elderly. The rScO2 was significantly different in the middle-aged (63 [56-69]) compared with the young participants (67 [59-74]; p < 0.001) and elderly participants (60 [55-66]; p < 0.001]. Women were significantly older compared with men (72 [62-79] v 66 [56-74]; p < 0.001]) and showed lower hemoglobin values (p < 0.001) and lower rScO2 (58 [52-63] v 65 [58-70]; p < 0.001]). Multiple regression analysis revealed age, sex, and hemoglobin as significant determinants of rScO2: 26.665 - (0.030 × age) + (2.581 × hemoglobin) + (2.799 × 0 for female sex). CONCLUSIONS: Baseline rScO2, as measured by the INVOS 5100, decreases with advanced age and is lower in women. New definitions of cerebral oxygen desaturation need to be analyzed in future trials that will evaluate neurologic outcome in the aging population or in women.