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

Abstract

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 rScO_2, 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.

Keywords: aging; cerebral oximetry; near-infrared spectroscopy.